研究成果

最新发表论文

2024

117. Layer-by-layer assembled 2D nanocomposites for extreme polarization optics
     Jiao Yang, Qunfeng Cheng*
     Natl. Sci. Rev., 2024, 11, nwae353. DOI:10.1093/nsr/nwae353
     Abstract
     .
     | PDF | Supplementary Information

116. Strong and tough MXene bridging-induced conductive nacre
     Jia Yan, Tianzhu Zhou, Xinyu Yang, Zejun Zhang, Lei Li, Zhaoyong Zou, Zhengyi Fu, Qunfeng Cheng*
     Angew. Chem. Int. Edit., 2024, 63, e202405228. DOI:10.1002/anie.202405228
     Abstract
     Nacre is a classic model, providing an inspiration for fabricating high-performance bulk nanocomposites with the two-dimensional platelets. However, the “brick” of nacre, aragonite platelet, is an ideal building block for making high-performance bulk nanocomposites. Herein, we demonstrated a strong and tough conductive nacre through reassembling aragonite platelets with bridged by MXene nanosheets and hydrogen bonding, not only providing high mechanical properties but also excellent electrical conductivity. The flexural strength and fracture toughness of the obtained conductive nacre reach ~282 MPa and ~6.3 MPa m1/2, which is 1.6 and 1.6 times higher than that of natural nacre, respectively. These properties are attributed to densification and high orientation degree of the conductive nacre, which is effectively induced by the combined interactions of hydrogen bonding and MXene nanosheets bridging. The crack propagations in conductive nacre are effectively inhibited through crack deflection with hydrogen bonding, and MXene nanosheets bridging between aragonite platelets. In addition, our conductive nacre also provides a self-monitoring function for structural damage and offers exceptional electromagnetic interference shielding performance. Our strategy of reassembling the aragonite platelets exfoliated from waste nacre into high-performance artificial nacre, provides an avenue for fabricating high-performance bulk nanocomposites through the sustainable reutilization of shell resources.
     | PDF | Supplementary Information

115. Anisotropic thermally conductive films based on two-dimensional nanomaterials
     Lei Li, Qunfeng Cheng*
     Interd. Mater., 2024, 3, 847-864. DOI:10.1002/idm2.12204
     Abstract
     The significant advancement of high-power densification and miniaturization in modern electronic devices has attracted increasing attention to effective thermal management. The primary objective of thermal management is to transfer excess heat from electronics to the outside environment through the use of thermal conductive materials. The anisotropic thermally conductive films (TCFs) based on two-dimensional (2D) nanomaterials exhibit outstanding controlled heat transfer capability, which effectively removes hotspots along the in-plane direction and provides thermal insulation along the cross-plane direction. However, a comprehensive review of anisotropic TCFs is rarely reported. Herein, we first discuss the intrinsic anisotropic thermal conductivity of 2D nanomaterials for preparing TCFs. Then, the preparation methods and anisotropic thermal conductivity of TCFs have been summarized and discussed. Furthermore, we conclude with the practical applications of TCFs for anisotropy thermal management. Finally, a conclusion of the challenges and outlook of TCFs is provided to promote their development in future scientific research.
     | PDF | Supplementary Information

114. Recent advances in the high performance MXenes nanocomposites
     Lei Li, Qunfeng Cheng*
     J. inorg. Mater., 2024, 39, 153-161. DOI:10.15541/jim20230306
     Abstract
     Two-dimensional transition metal carbon/nitride MXenes show promising applications in various fields due to their remarkable electrical and mechanical properties. Recently, the research of high performance MXenes nanocomposites (including one-dimensional fibers, two-dimensional films and three-dimensional blocks) has made remarkable progress. However, the mechanical properties are still far lower than the intrinsic mechanical properties of MXenes nanosheets, mainly due to the key scientific problems of voids, misalignment of MXenes nanosheets and weak interfaces. In order to solve the above problems, the intrinsic mechanical properties of MXenes nanosheets are firstly discussed in this work, then the development of high performance MXenes nanocomposites are summarized, and the latest research progress of high performance MXenes nanocomposites is discussed in detail, including how to eliminate void, improve the orientation of MXene nanosheets and enhance the interface interaction. Meanwhile, the applications of high performance MXenes nanocomposites in the fields of electric heating, thermal camouflage, electromagnetic shielding, sensing and energy storage are introduced. Finally, the challenges and future development directions of high performance MXenes nanocomposites are proposed.
     | PDF | Supplementary Information

113. Nanoconfined-water-induced ultrastrong isotropic MXene-bridged graphene sheets with remarkable electrochemical energy storage
     Jiao Yang, Qunfeng Cheng*
     Chinese Sci. Bull., 2024, 69, 1980-1982. DOI:10.1360/TB-2024-0241
     Abstract
     .
     | PDF | Supplementary Information

112. Scalable ultrastrong MXene films with superior osteogenesis
     Sijie Wan, Ying Chen, Chaojie Huang, Zongjun Huang, Cheng Liang, Xuliang Deng*, Qunfeng Cheng*
     Nature, 2024, 634, 1103-1110. DOI:10.1038/s41586-024-08067-8
     Abstract
     Titanium carbide MXene flakes have promising applications in aerospace, flexible electronic devices and biomedicine owing to their superior mechanical properties1 and electrical conductivity2 and good photothermal conversion3, biocompatibility4 and osteoinductivity5. It is highly desired yet very challenging to assemble MXene flakes into macroscopic high-performance materials in a scalable manner. Here we demonstrate a scalable strategy to fabricate high-performance MXene films by roll-to-roll-assisted blade coating (RBC) integrated with sequential bridging, providing good photothermal conversion and osteogenesis efficiency under near-infrared irradiation. MXene flakes were first bridged with silk sericin by hydrogen bonding and then assembled into macroscopic films using a continuous RBC process, followed by ionic bridging to freeze their aligned structure. The resultant large-scale MXene films with strong interlayer interactions are highly aligned and densified, exhibiting high tensile strength (755 MPa), toughness (17.4 MJ m−3) and electromagnetic interference (EMI) shielding capacity (78,000 dB cm2 g−1), as well as good ambient stability, photothermal conversion and bone regeneration performance. The proposed strategy not only paves a feasible way for realizing the practical applications of MXene in the fields of flexible EMI shielding materials and bone tissue engineering but also provides an avenue for the high-performance and scalable assembly of other two-dimensional flakes.
     | PDF | Supplementary Information

111. Discovery and Elimination Strategies of Voids in Two-Dimensional Carbon Nanocomposites
     Yuchen Li, Qunfeng Cheng*
     Accounts of Materials Research , 2024, 5, 358-370. DOI:10.1021/accountsmr.3c00255
     Abstract
     Two-dimensional carbon nanocomposites (TDCN) are assembled by two-dimensional carbon nanosheets and show promising applications in many fields such as unmanned aerial vehicles, aerospace, and smart wearable devices due to their exceptional performance including light weight, high strength, high electrical and thermal conductivities, etc. Compared with traditional carbon-fiber-reinforced composites, two-dimensional carbon nanosheets represented by graphene and titanium carbide (MXene) have outstanding mechanical properties, making them ideal candidates for fabricating high-performance nanocomposites. Over the past two decades, many researchers have developed many strategies to solve intrinsic issues in the fabrication of TDCN, such as poor dispersion, low orientation, weak interfacial interactions, etc. Although many achievements in mechanical properties of TDCN have been obtained, the mechanical performance of TDCN is still far below theoretical expectations based on the intrinsic performance of two-dimensional carbon nanosheets. We first found that there is an important issue ignored so far, void, resulting in low load transfer efficiency in TDCN. Recently, the investigations about voids’ characterization, analysis, and elimination have been demonstrated as a key scientific issue for further enhancing the performance of TDCN.

     In this Account, we will summarize significant advanced research in the discovery, characterization, influence, and elimination of voids in TDCN by our group and discuss the relevant reported works. We start by introducing the physical and chemical properties of two-dimensional carbon nanosheets, such as graphene and MXene, which are widely used for fabrication of TDCN. Then we systemically introduce fabrication strategies of TDCN such as filtration, layer-by-layer, superspreading, blade casting, and centrifugal casting. Employing these strategies, two-dimensional carbon nanosheets could be sufficiently dispersed and highly oriented, thus resulting in excellent mechanical properties. However, the mechanical properties of TDCN are still far lower than those of the intrinsic two-dimensional carbon nanosheet, which is mainly caused from existed voids. Then, we overview the research work about the discovery, characterization, and influence of voids on the mechanical properties of TDCN. Next, we systematically introduce a series of strategies to eliminate voids, such as synergistic interfacial interaction, filling, and force-induced alignment. Employing these strategies, TDCN results in excellent mechanical properties and remains high in electrical properties, which could be widely used in various fields such as electromagnetic interference shielding, thermal shielding, flexible supercapacitors, and flexible thermal management. Finally, we summarize the current technical challenges facing this field. We not only give a perspective of future void characterization and elimination strategies to further develop high-performance TDCN but also propose the concept for adjusting voids to achieve the functions in TDCN. More functional TDCN will be fabricated through control of voids size and distribution during the process of self-assembly of two-dimensional carbon nanosheets.

     | PDF | Supplementary Information

110. Improving strength and toughness of graphene film through metal ion bridging
     Zejun Zhang, Luping Zheng, Weixin Huang, Qunfeng Cheng*
     Proc. Natl. Acad. Sci. , 2024, 121, e2322663121. DOI:10.1073/pnas.2322663121
     Abstract
     The fangs, jaws, and mandibles of marine invertebrates such as Chiton and Glycera show excellent mechanical properties, which are mostly contributed to the interactions between metal (Fe, Cu, Zn, etc.) and oxygen-containing functional groups in proteins. Inspired by these load-bearing skeletal biomaterials, we improved tensile strength and toughness of graphene films through bridging graphene oxide (GO) nanosheets by metal ions. By optimizing the metal coordination form and density of cross-linking network. We revealed the relationship between mechanical properties and the unique spatial geometry of the GO nanosheets bridged by different valence metal ions. The results demonstrated that the divalent metal ions form tetrahedral geometry with carboxylate groups on the edges of the GO nanosheets, and the bond energy is relatively low, which is helpful for improving the toughness of resultant graphene films. While the trivalent metal ions are easily to form octahedral geometry with the GO nanosheets with higher bond energy, which is better for enhancing the tensile strength of graphene films. After reduction, the reduced GO (rGO) film bridged by divalent metal ions shows 43% improvement in toughness, while the rGO film bridged by trivalent metal ions shows 64% improvement in tensile strength. Our work reveals the mechanism of metal coordination bond energy and spatial geometry to improve the mechanical properties of graphene films, which lays a theoretical foundation for improving the tensile strength and toughness of resultant graphene films, and provides an avenue for fabricating high-performance graphene films and other two-dimensional nanocomposites.
     | PDF | Supplementary Information

109. Ultrastrong MXene film induced by sequential bridging with liquid metal
     Wei Li, Tianzhu Zhou, Zejun Zhang, Lei Li, Wangwei Lian, Yanlei Wang, Junfeng Lu, Jia Yan, Huagao Wang, Lei Wei, Qunfeng Cheng*
     Science , 2024, 385, 62-68. DOI:10.1126/science.ado4257
     Abstract
     Assembling titanium carbide (Ti3C2Tx) MXene nanosheets into macroscopic films presents challenges, including voids, low orientation degree, and weak interfacial interactions, which reduce mechanical performance. We demonstrate an ultrastrong macroscopic MXene film using liquid metal (LM) and bacterial cellulose (BC) to sequentially bridge MXene nanosheets (an LBM film), achieving a tensile strength of 908.4 megapascals. A layer-by-layer approach using repeated cycles of blade coating improves the orientation degree to 0.935 in the LBM film, while a LM with good deformability reduces voids into porosity of 5.4%. The interfacial interactions are enhanced by the hydrogen bonding from BC and the coordination bonding with LM, which improves the stress-transfer efficiency. Sequential bridging provides an avenue for assembling other two-dimensional nanosheets into high-performance materials.
     | PDF | Supplementary Information

108. Water-induced strong isotropic MXene-bridged graphene sheets for electrochemical energy storage
     Jiao Yang, Mingzhu Li, Shaoli Fang, Yanlei Wang, Hongyan He, Chenlu Wang, Zejun Zhang, Bicheng Yuan, Lei Jiang, Ray H. Baughman*, Qunfeng Cheng*
     Science , 2024, 383, 771-777. DOI:10.1126/science.adj3549
     Abstract
     Graphene and two-dimensional transition metal carbides and/or nitrides (MXenes) are important materials for making flexible energy storage devices because of their electrical and mechanical properties. It remains a challenge to assemble nanoplatelets of these materials at room temperature into in-plane isotropic, free-standing sheets. Using nanoconfined water-induced basal-plane alignment and covalent and π-π interplatelet bridging, we fabricated Ti3C2Tx MXene-bridged graphene sheets at room temperature with isotropic in-plane tensile strength of 1.87 gigapascals and moduli of 98.7 gigapascals. The in-plane room temperature electrical conductivity reached 1423 siemens per centimeter, and volumetric specific capacity reached 828 coulombs per cubic centimeter. This nanoconfined water-induced alignment likely provides an important approach for making other aligned macroscopic assemblies of two-dimensional nanoplatelets.
     | PDF | Supplementary Information

免费下载论文链接：https://www.science.org/stoken/author-tokens/ST-1700/full

107. Sustainable liquid metal-induced conductive nacre
     Jia Yan, Tianzhu Zhou, Jingsong Peng, Huagao Wang, Lei Jiang, Qunfeng Cheng*
     Science Bulletin , 2024. DOI:10.1016/j.scib.2024.01.033
     Abstract
     Nacre has inspired research to fabricate tough bulk composites for practical applications using inorganic nanomaterials as building blocks. However, with the considerable pressure to reduce global carbon emissions, preparing nacre-inspired composites remains a significant challenge using more economical and environmentally friendly building blocks. Here we demonstrate tough and conductive nacre by assembling aragonite platelets exfoliated from natural nacre, with liquid metal and sodium alginate used as the “mortar”. The formation of Gasingle bondOsingle bondC coordination bonding between the gallium ions and sodium alginate molecules reduces the voids and improves compactness. The resultant conductive nacre exhibits much higher mechanical properties than natural nacre. It also shows excellent impact resistance attributed to the synergistic strengthening and toughening fracture mechanisms induced by liquid metal and sodium alginate. Furthermore, our conductive nacre exhibits exceptional self-monitoring sensitivity for maintaining structural integrity. The proposed strategy provides a novel avenue for turning natural nacre into a valuable green composite.
     | PDF | Supplementary Information

2023

106. Interlocking-Governed Ultra-Strong and Highly Conductive MXene Fibers Through Fluidics-Assisted Thermal Drawing
     Tianzhu Zhou, Can Cao, Shixing Yuan, Zhe Wang, Qi Zhu, Hao Zhang, Jia Yan, Fan Liu, Ting Xiong, Qunfeng Cheng*, Lei Wei*
     Advanced Materials , 2023, 35, 2305807. DOI:10.1002/adma.202305807
     Abstract
     High-performance MXene fibers are always of significant interest for flexible textile-based devices. However, achieving high mechanical property and electrical conductivity remains challenging due to the uncontrolled loose microstructures of MXene (Ti3C2Tx and Ti3CNTx) nanosheets. Herein, high-performance MXene fibers directly obtained through fluidics-assisted thermal drawing are demonstrated. Tablet interlocks are formed at the interface layer between the outer cyclic olefin copolymer and inner MXene nanosheets due to the thermal drawing induced stresses, resulting in thousands of meters long macroscopic compact MXene fibers with ultra-high tensile strength, toughness, and outstanding electrical conductivity. Further, large-scale woven textiles constructed by these fibers offer exceptional electromagnetic interference shielding performance with excellent durability and stability. Such an effective and sustainable approach can be applied to produce functional fibers for applications in both daily life and aerospace.
     | PDF | Supplementary Information

105. Superior Synergistic Osteogenesis of MXene-Based Hydrogel through Supersensitive Drug Release at Mild Heat
     Ying Chen, Wenwen Liu, Sijie Wan, Huagao Wang, Yumin Chen, Han Zhao, Chenguang Zhang, Kaihui Liu, Tuanfeng Zhou, Lei Jiang, Qunfeng Cheng*, Xuliang Deng*
     Advanced Functional Materials , 2024, 34, 2309191. DOI:10.1002/adfm.202309191
     Abstract
     Near-infrared (NIR) responsive smart drug delivery systems could provide efficient osteogenesis through the synergy of heat and drugs. However, such systems are hampered by an inability to allow supersensitive drug release through mild heat. Here superior osteogenesis is demonstrated using a biocompatible dexamethasone (Dex)-loaded MXene-poly(N-isopropylacrylamide)-co-N-(Hydroxymethyl) acrylamide hydrogel capable of the supersensitive release of Dex at ≈42 °C upon NIR irradiation. Furthermore, the hydrogel can significantly promote bone regeneration under NIR irradiation due to the synergistic anti-apoptosis and osteogenic differentiation of bone-derived mesenchymal stem cells induced by the mild heat and supersensitive release of Dex. The resulting osteogenesis efficiency of hydrogels surpass efficiencies previously reported for heat and drug stimulation and their combination. The synergistic osteogenesis strategy is characterized by near-instantaneous, noninvasive, and precise treatment through temporal NIR irradiation.
     | PDF | Supplementary Information

104. Strong, tough, and thermally conductive nacre-inspired boron nitride nanosheet/epoxy layered nanocomposites
     Huagao Wang, Rongjian Lu, Lei Li, Cheng Liang, Jia Yan, Rui Liang, Guoxing Sun, Lei Jiang, Qunfeng Cheng*
     Nano Research, 2023, 1-9. DOI:10.1007/s12274-023-6101-4
     Abstract
     Thermally conductive polymer nanocomposites integrated with lightweight, excellent flexural strength, and high fracture toughness (KIc) would be of great use in many fields. However, achieving all of these properties simultaneously remains a great challenge. Inspired by natural nacre, here we demonstrate a lightweight, strong, tough, and thermally conductive boron nitride nanosheet/epoxy layered (BNNEL) nanocomposite. Because of the layered structure and enhancing the interfacial interactions through hydrogen bonding and Si–O–B covalent bonding, the resulting nacre-inspired BNNEL nanocomposites show high fracture toughness of ∼ 4.22 MPa·m1/2, which is 7 folds as high as pure epoxy. Moreover, the BNNEL nanocomposites demonstrate sufficient flexural strength (∼ 168.90 MPa, comparable to epoxy resin), while also being lightweight (∼ 1.23 g/cm3). Additionally, the BNNEL nanocomposites display a thermal conductivity (κ) of ∼ 0.47 W/(m·K) at low boron nitride nanosheet loading of 2.08 vol.%, which is 2.7 times higher than that of pure epoxy resin. The developed nacre-inspired strategy of layered structure design and interfacial enhancement provides an avenue for fabricating high mechanical properties and thermally conductive polymer nanocomposites.
     | PDF | Supplementary Information

103. Recent Advances in the Nacre-inspired Layered Polymer Nanocomposites by Ice Templating Technique
     Huagao Wang, Qunfeng Cheng*
     Acta Chimica Sinica , 2023, 81, 1231-1239. DOI:10.6023/A23050207
     Abstract
     Ice templating, known as directional freeze casting, is a novel technique for constructing laminar porous materials by homogeneously dispersing or dissolving the building blocks, solvents and additives and using the “liquid-solid-gas” phase transition of the solvent. Inspired by the “brick-mortar” layered structure, the lamellar scaffold prepared from ice templating can be densified to construct nacre-like composite. This work presents a timely and systematic investigation and summary of frontier progresses of layered polymer nanocomposites constructed by the ice templating technique. Firstly, the densification strategies are classified according the different thickness of “brick” into three strategies: lamellar scaffold-filled polymer, hot-pressing treatment and mineralization. And typical layered polymer nanocomposites constructed by each strategy and their properties are also presented with classical examples. Subsequently, the design and functional applications of layered polymer nanocomposites are analyzed and discussed, such as the modulation of microstructures, introduction of functional building blocks, and enhancement of interfacial interactions, which not only improve the mechanical properties of layered polymer nanocomposites, but also endow them with functional applications, such as electromagnetic shielding, thermal conductivity and self-monitoring of structural integrity. Finally, we provide an outlook on the future directions and challenges of the structural design, performance optimization and application expansion of nacre-inspired layered polymer nanocomposites constructed by the ice templating technique.
     | PDF | Supplementary Information

102. Notonecta glauca-inspired smart devices
     Jiajun Mao, Qunfeng Cheng*
     Matter, 2023, 6, 2102-2105. DOI:10.1016/j.matt.2023.05.031
     Abstract
     There are abundant resources in the sea, and mankind has been relying on these resources for the past few centuries. However, the contradiction between the rapid growth of population and the shortage of global freshwater, food, and energy supply is becoming increasingly prominent. The vast surface of the ocean is a huge liquid-gas interface, highly active and accompanied by a large amount of resource and energy exchange. This Preview highlights a design in a recent issue of Matter of a backswimmer (Notonecta glauca)-inspired device (BSD), which adapts to the posture of floating and deep diving in the ocean to realize the convenience of marine resources exploration.
     | PDF | Supplementary Information

101. Tough and Conductive Nacre-inspired MXene/epoxy Layered Bulk Nanocomposites
     Huagao Wang, Rongjian Lu, Jia Yan, Jingsong Peng, Antoni P. Tomsia, Rui Liang, Guoxing Sun, Mingjie Liu, Lei Jiang, Qunfeng Cheng*
     Angew Chem Int Ed , 2023.62.e202216874. DOI:10.1002/anie.202216874
     Abstract
     A long-standing quest in materials science has been the development of tough epoxy resin nanocomposites used in numerous applications. Inspired by nacre, herein, we report tough and conductive MXene/epoxy layered bulk nanocomposites. The orientation of MXene lamellar scaffolds is enhanced by annealing treatment. The improved interfacial interactions between MXene lamellar scaffold and epoxy through surface chemical modification resulted in a synergistic effect. Tailoring the interlayer spacing of MXene nanosheets to a critical distance resulted in the fracture toughness about eight times higher than pure epoxy, surpassing other epoxy nanocomposites. Our nacre-inspired MXene/epoxy layered bulk nanocomposites also show high electrical conductivity that provides self-monitoring capability to the structure integrity and exhibits an excellent electromagnetic interference shielding efficiency. Our proposed strategy provides an avenue for fabricating high-performance epoxy nanocomposites.
     | PDF | Supplementary Information

2022

100. MXene based nanocomposite films
     Lei Li, Qunfeng Cheng*
     Exploration, 2022, 2, 20220049. DOI:10.1002/EXP.20220049
     Abstract
     Since the first report in 2011, two-dimensional transition metal carbide/nitride MXenes have aroused widespread attention owing to the particular structure and physiochemical properties. In the last few years, MXene-based nanocomposite films have been widely investigated, showing promising applications in many fields. However, poor mechanical properties and thermal/electrical conductivities of MXene-based nanocomposite films still limited their practical applications. Herein, we summarize the fabrication approach of MXene-based nanocomposite films and discuss the mechanical properties and other applications, including electromagnetic interference shielding, thermal conductivity, and supercapacitors. Then, several vital factors for fabricating high performance MXene based nanocomposite films have been refined. To further fabricate high performance MXene-based nanocomposite films, some effective sequential bridging strategies are also discussed. Lastly, a conclusion of the challenges and opportunities of MXene-based nanocomposite films is provided to facilitate their development and application for various purposes in the future of scientific research.
     | PDF | Supplementary Information

99. Bioinspired nanocomposite films with graphene and MXene
    Lei Li, Qunfeng Cheng*
    Giant , 2022, 12, 100117. DOI:10.1016/j.giant.2022.100117
    Abstract
    Two dimensional nanomaterials, such as graphene and MXene, have been widely used to fabricate high performance nanocomposite films owing to their unique structure and excellent physiochemical properties, showing enormous potential applications in many areas. However, the existing voids and wrinkling in the nanocomposite films inevitably impedes realizing the high performance of the nanocomposite films during the assembly process of graphene and MXene nanosheets. Nacre provides an inspiration for fabricating high performance graphene and MXene nanocomposite films through constructing a high alignment structure and strong interface interactions. In this review, we summarize the preparation approaches of graphene and MXene nanocomposite films and discuss the mechanical properties. Then, several effective strategies for assembling graphene and MXene nanosheets have been concluded and discussed. Meanwhile, we also summarize and discuss the applications of graphene and MXene nanocomposite films including electromagnetic interference (EMI) shielding and thermal management. Finally, outlooks and challenges are proposed to promote their progress and applications in the future.
    | PDF | Supplementary Information

98. Bioinspired light-driven photonic crystal actuator with MXene-hydrogel muscle
    Mingzhu Li*, Lei Yuan, Yifan Liu, Florian Vogelbacher, Xiaoyu Hou, Yanlin Song, Qunfeng Cheng
    Cell Reports Physical Science, 2022, 3, 100915. DOI:10.1016/j.xcrp.2022.100915
    Abstract
    The butterfly Apatura ilia’s wings change colors during flapping, which plays a major role in conveying information and avoiding predators. Inspired by the muscle-driven flapping mechanism, here, we fabricate a highly efficient photothermally responsive MXene-hydrogel muscle and achieve a dynamic structural color imaging system based on the MXene-hydrogel muscle manipulated photonic crystal actuator arrays. Our optimized MXene-hydrogel-muscle artificial muscle has a stable and quick photothermal response owing to the high photothermal transformation efficiency of MXene (∼100%). Consequently, our photonic crystal (PhC) actuator exhibits robust structural stability and fatigue resistance (more than 500 cycles), and its response time is ∼5 s. The PhC actuator can give real-time visual feedback in response to heating and near-infrared irradiation. They offer exciting possibilities for applications in sensors, displays, camouflage coatings, cryptography, and many other fields. Our experiments and theoretical analysis reveal the quantitative structure-activity relationship of the responsive PhC actuator.
    | PDF | Supplementary Information

97. Ultrastrong MXene films via the synergy of intercalating small flakes and interfacial bridging
    Sijie Wan , Xiang Li, YingChen, Nana Liu, Shijun Wang, Yi Du,
    Zhiping Xu, Xuliang Deng, Shixue Dou, Lei Jiang, Qunfeng Cheng*
    Nat Commun , 2022, 13, 7340. DOI:10.1038/s41467-022-35226-0
    Abstract
    Titanium carbide MXene combines high mechanical and electrical properties and low infrared emissivity, making it of interest for flexible electromagnetic interference (EMI) shielding and thermal camouflage film materials. Conventional wisdom holds that large MXene is the preferable building block to assemble high-performance films. However, the voids in the films comprising large MXene degrade their properties. Although traditional crosslinking strategies can diminish the voids, the electron transport between MXene flakes is usually disrupted by the insulating polymer bonding agents, reducing the electrical conductivity. Here we demonstrate a sequential densification strategy to synergistically remove the voids between MXene flakes while strengthening the interlayer electron transport. Small MXene flakes were first intercalated to fill the voids between multilayer large flakes, followed by interfacial bridging of calcium ions and borate ions to eliminate the remaining voids, including those between monolayer flakes. The obtained MXene films are compact and exhibit high tensile strength (739 MPa), Young’s modulus (72.4 GPa), electrical conductivity (10,336 S cm−1), and EMI shielding capacity (71,801 dB cm2 g−1), as well as excellent oxidation resistance and thermal camouflage performance. The presented strategy provides an avenue for the high-performance assembly of other two-dimensional flakes.
    | PDF | Supplementary Information

96. MXene-Regulated Perovskite Vertical Growth for High-Performance Solar Cells
    Chao Wu,Wenzhong Fang, Qunfeng Cheng, Jing Wan, Rui Wen, Yang Wang, Yanlin Song, Mingzhu Li*
    Angew Chem Int Ed, 2022, 61, e202210970. DOI:10.1002/anie.202210970
    Abstract
    Defects at the interfaces of perovskite (PVK) thin films are the main factors responsible for instability and low photoelectric conversion efficiency (PCE) of PVK solar cells (PSCs). Here, a SnO2-MXene composite electron transport layer (ETL) is used in PSCs to improve interfacial contact and passivate defects at the SnO2/perovskite interface. The introduced MXene regulates SnO2 dispersion and induces a vertical growth of PVK. The lattice matching of MXene and perovskite suppresses the concentration of interfacial stress, thereby obtaining a perovskite film with low defects. Compared with SnO2-based device, the PCE of SnO2-MXene-based device is improved by 15 % and its short-circuit current is up to 25.07 mA cm−2. Furthermore, unencapsulated device maintained about 90 % of its initial efficiency even after 500 h of storage at 30–40 % relative humidity in ambient air. The composite ETL strategy provides a route to engineer interfacial passivation between metal halide perovskites and ETLs.
    | PDF | Supplementary Information

95. Nacre inspired robust self-encapsulating flexible perovskite photodetector
    Yan Zhan, Qunfeng Cheng, Jingsong Peng, Yao Zhao, Florian Vogelbacher, Xintao Lai, Fuyi Wang, Yanlin Song, Mingzhu Li*
    Nano Energy, 2022, 98, 107254. DOI:10.1016/j.nanoen.2022.107254
    Abstract
    The unique properties of metal halide perovskites give them great potential for applications in portable and wearable optoelectronics. However, the intrinsic brittleness of perovskites favors easy crack propagation that deteriorates the optoelectronic performance of the devices. Inspired by nacre, we propose flexible perovskite thin films fabricated by antisolvent-assisted self-encapsulation of polymer and imprinting techniques during crystallization. Such an approach results in synchronous formation of polymer-glued perovskite grains exhibiting nacre-like “brick-and-mortar” structure. The deformable composite architecture bonding hemisphere-shaped grating (HG) and porous photonic crystal (PC) (HG-PC) improves its crystalline quality and light-harvesting capability. An HG-PC photodetector (PD) with high responsivity of 17.31 A/W and detectivity of 5.02 × 1013 Jones is achieved. Our flexible HG-PC PD retains 95% of the initial photocurrent after 1000 bending cycles at 2 mm curvature radius. This solvent-driven self-encapsulation strategy offers an innovative and universal approach for highly efficient flexible optoelectronics.
    | PDF | Supplementary Information

94. Micro-Nano Structure Functionalized Perovskite Optoelectronics: From Structure Functionalities to Device Applications
    Yan Zhan, Qunfeng Cheng, Yanlin Song, Mingzhu Li*
    Adv. Funct. Mater., 2022, 32, 2200385. DOI:10.1002/adfm.202200385
    Abstract
    Metal halide perovskite, an emerging photosensitive semiconductor, has been widely employed in solar cells, light-emitting diodes, photodetectors, and lasers owing to its excellent photophysical properties and simple solution preparation processing. However, as a photoactive layer, the higher refractive index and thinner thickness of perovskite film can cause reflection and transmission at the interface, and confine the emitted light within devices, resulting in the poor incident photon absorption and emitted photon extraction. In addition, the intrinsic brittleness of perovskite material restricts its potential applications in flexible optoelectronics. Therefore, great effort has been put into micro-nano structured perovskite optoelectronics, and the reported reviews mainly focus on the fabrication process of micro-nano patterned perovskite. Herein, the functionalities of micro-nano structures in optoelectronics, including improving the light trapping, light extraction, light modulation, carrier dynamics, mechanical robustness, and other novel functionalities, are comprehensively reviewed. The specific applications of these functionalities in perovskite-based optoelectronic devices are then discussed in detail to provide a better understanding of the photophysical properties of micro-nano structure functionalized optoelectronics. Finally, promising strategies to promote the multifunctional commercial applications of micro-nano structured perovskite optoelectronics are provided.
    | PDF | Supplementary Information

93. A biomineralization-inspired strategy of self-encapsulation for perovskite solar cells
    Yan Zhan, Jingsong Peng, Can Cao, Qunfeng Cheng*,
    Nano Energy, 2022, 101, 107575. DOI:10.1016/j.nanoen.2022.107575
    Abstract
    Solution-processed perovskite films are promising for the cost-effective fabrication of optoelectronic devices. However, the poor environmental stability of perovskite materials hampers their commercial development, and a challenge remains in the universal technology for self-encapsulating perovskite films through controlling the crystallization. Herein, we designed a strategy of crystal growth assisted by the polymer bottom-up dynamic diffusion and created the self-encapsulated perovskite films with preferred crystalline orientation by mimicking the typical process of biomineralization. Thin polymer distributed at the surface, buried interface, and grain boundaries facilitated the efficient defect passivation and self-encapsulation of the entire film, and also, the coordination interaction between polymer and perovskite aligned the interface energy band. These collaborative advantages endowed perovskite solar cells (PSCs) with power conversion efficiency (PCE) of 22.90 %. In addition, the self-encapsulated perovskite films exhibited negligible decomposition and PCE remained 90 % after being stored in ambient air (30–50 % humidity) for 90 days. This universal strategy of biomineralization-inspired polymer self-encapsulating opens up a new avenue for efficient and stable perovskite optoelectronics.
    | PDF | Supplementary Information

92. Ginkgo seed shell provides a unique model for bioinspired design
    Yuanyuan Zhang, Jiajun Mao, Jingsong Peng, Antoni P. Tomsia, Lei Jiang, and Qunfeng Cheng*
    P. Natl. Acad. Sci. U.S.A., 2022, 119, e2211458119. DOI:10.1073/pnas.2211458119
    Abstract
    Natural structural materials typically feature complex hierarchical anisotropic architectures, resulting in excellent damage tolerance. Such highly anisotropic structures, however, also provide an easy path for crack propagation, often leading to catastrophic fracture as evidenced, for example, by wood splitting. Here, we describe the weakly anisotropic structure of Ginkgo biloba (ginkgo) seed shell, which has excellent crack resistance in different directions. Ginkgo seed shell is composed of tightly packed polygonal sclereids with cell walls in which the cellulose microfibrils are oriented in a helicoidal pattern. We found that the sclereids contain distinct pits, special fine tubes like a “screw fastener,” that interlock the helicoidal cell walls together. As a result, ginkgo seed shell demonstrates crack resistance in all directions, exhibiting specific fracture toughness that can rival other highly anisotropic natural materials, such as wood, bone, insect cuticle, and nacre. In situ characterization reveals ginkgo’s unique toughening mechanism: pit-guided crack propagation. This mechanism forces the crack to depart from the weak compound middle lamella and enter into the sclereid, where the helicoidal cell wall significantly inhibits crack growth by the cleavage and breakage of the fibril-based cell walls. Ginkgo’s toughening mechanism could provide guidelines for a new bioinspired strategy for the design of high-performance bulk materials.
    | PDF | Supplementary Information

91. Ultra-compact MXene fibers by continuous and controllable synergy of interfacial interactions and thermal drawing-induced stresses
    Tianzhu Zhou, Yangzhe Yu, Bing He, Zhe Wang, Ting Xiong, Zhixun Wang ,Yanting Liu, Jiwu Xin, Miao Qi, Haozhe Zhang, Xuhui Zhou, Liheng Gao, Qunfeng Cheng*, LeiWei*
    Nat Commun, 2022, 13, 4564. DOI:10.1038/s41467-022-32361-6
    Abstract
    Recent advances in MXene (Ti3C2Tx) fibers, prepared from electrically conductive and mechanically strong MXene nanosheets, address the increasing demand of emerging yet promising electrode materials for the development of textile-based devices and beyond. However, to reveal the full potential of MXene fibers, reaching a balance between electrical conductivity and mechanical property is still the fundamental challenge, mainly due to the difficulties to further compact the loose MXene nanosheets. In this work, we demonstrate a continuous and controllable route to fabricate ultra-compact MXene fibers with an in-situ generated protective layer via the synergy of interfacial interactions and thermal drawing-induced stresses. The resulting ultra-compact MXene fibers with high orientation and low porosity exhibit not only excellent tensile strength and ultra-high toughness, but also high electrical conductivity. Then, we construct meter-scale MXene textiles using these ultra-compact fibers to achieve high-performance electromagnetic interference shielding and personal thermal management, accompanied by the high mechanical durability and stability even after multiple washing cycles. The demonstrated generic strategy can be applied to a broad range of nanostructured materials to construct functional fibers for large-scale applications in both space and daily lives.
    | PDF | Supplementary Information

90. Large-Area Ultrastrong and Stiff Layered MXene Nanocomposites by Shear-Flow-Induced Alignment of Nanosheets
    Tianxu Zhou, Chuangqi Zhao*, Yunhao Liu, Jin Huang, Hangsheng Zhou, Zhidong Nie, Meng Fan, Tianyi Zhao, Qunfeng Cheng, and Mingjie Liu*
    ACS Nano, 2022, 16, 12013-12023. DOI:10.1021/acsnano.2c02062
    Abstract
    To shield increasingly severe radiation pollution, ultrathin MXene-based electromagnetic interference (EMI) shielding materials with excellent mechanical properties are urgently demanded in wearable electrical devices or aerospace fields. However, it is still a challenge to fabricate ultrastrong and stiff MXene-based nanocomposites with excellent EMI shielding capacity in a universal and scalable manner. Here, inspired by the natural nacre structure, we propose an efficient superspreading strategy to construct a highly oriented layered “brick-and-mortar” structure using shear-flow-induced alignment of MXene nanosheets at an immiscible hydrogel/oil interface. A continuous and large-area MXene nanocomposite film has been fabricated through a homemade industrial-scale continuous fabrication setup. The prepared MXene nanocomposite films exhibit a tensile strength of 647.6 ± 56 MPa and a Young’s modulus of 59.8 ± 6.1 GPa, respectively. These outstanding mechanical properties are attributed to the continuous interphase layer that formed between the well-aligned MXene nanosheets. Moreover, the obtained MXene nanocomposites also show great EMI shielding effectiveness (51.6 dB). We consider that our MXene-based nanocomposite films may be potentially applied as electrical or aerospace devices with superior mechanical properties and high EMI shielding capacity.
    | PDF | Supplementary Information

89. Accurate determination of anisotropic thermal conductivity for ultrathin composite film
    QiuHao Zhu, JingSong Peng, Xiao Guo, RuXuan Zhang, Lei Jiang, Qunfeng Cheng*,Wen-Jie Liang*
    Chinese Physics B, 2022, 31,108102. DOI:10.1088/1674-1056/ac6ee5
    Abstract
    Highly anisotropic thermal conductive materials are of significance in thermal management applications. However, accurate determination of ultrathin composite thermal properties is a daunting task due to the tiny thermal conductance, severely hindering the further exploration of novel efficient thermal management materials, especially for size-confined environments. In this work, by utilizing a hybrid measuring method, we demonstrate an accurate determination of thermal properties for montmorillonite/reduced graphene oxide (MMT/rGO) composite film with a thickness range from 0.2 μ m to 2 μ m. The in-plane thermal conductivity measurement is realized by one-dimensional (1D) steady-state heat conduction approach while the cross-plane one is achieved via a modified 3ω method. As-measured thermal conductivity results are cross-checked with different methods and known materials, revealing the high measurement accuracy. A high anisotropic ratio of 60.5, independent of composite thickness, is observed in our measurements, further ensuring the negligible measurement error. Notably, our work develops an effective approach to the determination of ultrathin composite thermal conductivity, which may promote the development of ultrathin composites for potential thermal-related applications.
    | PDF | Supplementary Information

88. MXene 纤维的制备, 性能及应用研究进展
    梁程, 程群峰*
    复合材料学报, 2022, 39, 4227-4243. DOI:10.13801/j.cnki.fhclxb.20220725.003
    Abstract
    二维过渡金属碳/氮化物(MXenes)是一种新颖的二维纳米材料，具有优异的电学、力学性能及丰富的表面官能团，在功能材料领域受到了广泛关注，常被作为基元材料构筑宏观复合材料，其中MXene纤维有望成为继石墨烯纤维后另一种结构-功能一体化纤维材料，在多功能织物、传感、能源、电磁屏蔽等领域显示出巨大的应用前景。但目前MXene复合纤维的力学和电学性能与MXene纳米材料本征性能差距较大，主要原因是组装MXene纳米片过程中产生的褶皱、无序结构、界面作用力弱等问题，往往导致MXene纤维内部的孔隙、缺陷存在及纤维外形不规则等。针对MXene纤维研究过程中存在的问题及未来研究方向，本文做了详细综述，首先介绍MXene纤维的制备方法，然后详细阐述MXene复合纤维的力学和电学性能，并讨论提升其性能的策略。同时通过一些实例，综述了MXene复合纤维的应用。最后总结了MXene纤维存在的关键科学问题和挑战，并对MXene纤维的未来发展和前景进行了展望及对未来MXene纤维的研究和应用提供一些帮助。
    | PDF | Supplementary Information

87. Nacre-Inspired Graphene-based Multifunctional Nanocomposites
    Jingsong Peng, Qunfeng Cheng*
    Acta Phys. -Chim. Sin., 2022, 38(5),2005006 (1 of 13). DOI:10.3866/PKU.WHXB202005006
    Abstract
    Graphene is a 2D nanocomposite that has been gaining popularity in the research community in recent years. It is light weight with high tensile strength and excellent electrical conductivity. While graphene nanosheets are typically assembled into macroscopic nanocomposites, their beneficial properties may degrade from the aggregation of nanosheets owing to the weak interfacial interactions caused by random orientation and many other obstacles. Thus, finding an effective way to assemble the graphene nanosheets while not impacting its intrinsic properties is challenging. In nature, live organisms have always assembled numerous nanomaterials into high-performance nanocomposites. For example, nacre is composed of aragonite nanoplatelets and biopolymers such as protein and chitin. The aragonite nanoplatelets with a 95% volume fraction are stacked into a layered structure and “glued” together by biopolymers based on the “brick-and-mortar” architecture. The fracture toughness is 3000 times higher than natural aragonite minerals owing to the “extrinsic toughening mechanism” from the crack deflection and bridging in the “brick-and-mortar” architecture. We propose a nacre-inspired layered structure in graphene-based nanocomposites with two complementary strategies: constructing nacre-like and inverse nacre-like structures. This paper first introduces the structure and toughening mechanism of nacre and clarify the advantages of a bioinspired strategies. Then, some of the recent work on nacre-inspired graphene-based multifunctional nanocomposites is discussed. To construct the nacre-like structure, we fabricated graphene-based fibers and membranes with graphene as the main component. The nacre-like graphene-based nanocomposites have excellent tensile strength and toughness due to the synergistic effects from interfacial interactions and building blocks. It also demonstrated high electrical conductivity, which makes it suitable for electromagnetic interference shielding or supercapacitors. We also fabricated inverse nacre-like graphene-based nanocomposites with a small amount of graphene. The inverse nacre-like graphene-based nanocomposites has a layered structure and exhibited the “extrinsic toughening mechanism” seen in nacre. Consequently, the inverse nacre-like graphene-based nanocomposites possesses high fracture toughness that pushes the limit of “mixing rule”. With the addition of graphene, the inverse nacre-like nanocomposites are suitable for use in many applications such as electrical conductivity, electrical heating, temperature measurement and many other functions. Finally, our study summarizes the strategies to overcome the obstacles we encountered during the assembly process to construct both the nacre-like and inverse nacre-like structures that were based on graphene. Some of the challenges we encountered include the small sample size, the quality of graphene nanosheets and developing hierarchical assembly techniques. The upcoming trends in nacre-inspired graphene-based multifunctional nanocomposites will also be discussed.
    | PDF | Supplementary Information

2021

86. Strong, conductive aramid fiber functionalized by graphene
    Can Cao, Jingsong Peng, Xiumin Liang, Eduardo Saiz, Stephan E. Wolf,Hanoch Daniel Wagner,Lei Jiang, Qunfeng Cheng* Composites Part A., 2021, 140,106161. DOI: 10.1016/j.compositesa.2020.106161
    Abstract
    The surface modification of aramid fibers is an essential and potent approach to manipulate and improve fiber properties. Biogenic fibers are in stark contrast, as exemplified by the case of natural silk fibers. This highperformance fiber features a surface functionalization as a thin sericin film enwraps it for improving the mechanical properties of silks. Inspired by this unique sheath structure of biogenic silk, we improved the performance of aramid fibers by exploiting a coating composed of reduced graphene oxide nanosheets that selfassemble on the fiber surface guided by hydrogen bonding and π-π stacking interactions. The graphene functionalized aramid fibers show a remarkable 1 GPa improvement in tensile strength. Moreover, the functionalized aramid fiber also shows high electrical conductivity which preserved 99% of its conductivity even after 100 cycles. Our approach provides a universal strategy for improving the performance of the fiber via surface functionalization by graphene nanosheets.
    | PDF | Supporting Information
87. High-strength scalable MXene films through bridging-induced densification
    Sijie Wan, Xiang Li, Ying Chen, Nana Liu, Yi Du, Shixue Dou, Lei Jiang, and Qunfeng Cheng*
    Science, 2021, 374(6563), 96-99. DOI:10.1126/science.abg2026
    Abstract
    MXenes are a growing family of two-dimensional transition metal carbides and/or nitrides that are densely stacked into macroscopically layered films and have been considered for applications such as flexible electromagnetic interference (EMI) shielding materials. However, the mechanical and electrical reliabilities of titanium carbide MXene films are affected by voids in their structure. We applied sequential bridging of hydrogen and covalent bonding agents to induce the densification of MXene films and removal of the voids, leading to highly compact MXene films. The obtained MXene films show high tensile strength, in combination with high toughness, electrical conductivity, and EMI shielding capability. Our high-performance MXene films are scalable, providing an avenue for assembling other two-dimensional platelets into high-performance films.
    | PDF | Supplementary Information
88. Stiff and tough PDMS-MMT layered nanocomposites visualized by AIE luminogens
    Jingsong Peng, Antoni P. Tomsia, Lei Jiang, Ben Zhong Tang* & Qunfeng Cheng*
    Nature Communications., 2021, 12, 4539. DOI: 10.1038/s41467-021-24835-w
    Abstract
    Polydimethylsiloxane (PDMS) is a widely used soft material that exhibits excellent stability and transparency. But the difficulty of fine-tuning its Young’s modulus and its low toughness significantly hinder its application in fields such as tissue engineering and flexible devices. Inspired by nacre, here we report on the development of PDMS-montmorillonite layered (PDMS-MMT-L) nanocomposites via the ice-templating technique, resulting in 23 and 12 times improvement in Young’s modulus and toughness as compared with pure PDMS. Confocal fluorescence microscopy assisted by aggregation-induced emission (AIE) luminogens reveals three-dimensional reconstruction and in situ crack tracing of the nacre-inspired PDMS-MMT-L nanocomposite. The PDMS-MMT-L nanocomposite is toughened with mechanisms such as crack deflection and bridging. The AIE-assisted visualization of the crack propagation for nacre-inspired layered nanocomposites provides an advanced and universal characterization technique for organic-inorganic nanocomposites.
    | PDF | Supporting Information
89. Strong Reduced Graphene Oxide Coated Bombyx mori Silk
    Can Cao, Zongkai Lin, Xiaochen Liu, Yanyan Jia, Eduardo Saiz, Stephan E. Wolf, Hanoch Daniel Wagner, Lei Jiang, Qunfeng Cheng*
    Adv. Funct. Mater., 2021, 31(34), 2102923. DOI:10.1002/adfm.202102923
    Abstract
    Bombyx mori silks possess great potential in textile industries due to the large-scale green production. However, the demand for silks with functional as well as mechanical properties are continuously rising due to the emergence of other functional textiles. It remains a great challenge to functionalize natural silk and simultaneously improve its mechanical properties. Inspired by the relationship between natural core–sheath structure and mechanical properties of cocoon silk, the application of a thin reduced graphene oxide (rGO) layer coated B. mori silk (GS) is shown via hydrogen interfacial interaction. The resultant rGO-coated silk exhibits a remarkable tensile strength of 1137.7 MPa and toughness of 304.5 MJ m−3, which are 1.9 and 2.6 times higher than that of pure B. mori silk, respectively. Moreover, the GS shows a high electrical conductivity of 0.37 S m−1 with great thermal and deformation sensitivity. The bioinspired approach provides a universal and facile strategy for functionalizing natural fibers by applying rGO nanosheets surface coating.
    | PDF | Supplementary Information
90. Bioinspired Color Switchable Photonic Crystal Silicone Elastomer Kirigami
    Xintao Lai, Jingsong Peng, Qunfeng Cheng, Antoni P. Tomsia, Guanlei Zhao, Lei Liu, Guisheng Zou, Yanlin Song, Lei Jiang, Mingzhu Li*
    Angew. Chem. Int. Ed., 2021, 60(20), 14307-14312. DOI: 10.1002/anie.202103045
    Abstract
    Bioinspired dynamic structural color has great potential for use in dynamic displays, sensors, cryptography, and camouflage. However, it is quite rare for artificial structural color devices to withstand thousands of cycles. Male hummingbird’s crowns and gorgets are brightly colored, demonstrating frequent color switching that is induced by regulating the orientation of the feathers through movement of skin or joints. Inspired by this unique structural color modulation, we demonstrate a flexible, mechanically triggered color switchable sheet based on a photonic crystal (PhC)-coated polydimethylsiloxane (PDMS) kirigami (PhC-PDMS kirigami) made by laser cutting. Finite element modeling (FEM) simulation reveals that the thickness of PDMS kirigami and the chamfer at the incision induced by laser cutting both dominate the out-of-plane deformation through in-plane stretching. The bioinspired PhC-PDMS kirigami shows precisely programmable structural color and keeps the color very well after recycling over 10 000 times. This bioinspired PhC-PDMS kirigami also shows excellent viewability even in bright sunlight, high readability, robust functionality, technical flexibility, and mechanical durability, which are readily exploitable for applications, such as chromic mechanical monitors for the sports industry or for medical applications, wearable camouflage, and security systems.
    | PDF | Supporting Information
91. Chemical Strategies for Making Strong Graphene Materials
    Tianzhu Zhou, Qunfeng Cheng*
    Angew. Chem. Int. Ed., 2021, 60(34), 18397-18410. DOI:10.1002/anie.202102761
    Abstract
    Graphene materials have been widely applied in various fields because of their remarkable mechanical and electrical properties. However, two obstacles arise during the assembly of graphene platelets into macroscale graphene materials and composites that impair the performance of the resultant graphene materials: 1) the voids between the graphene platelets, and 2) the wrinkling of the graphene platelets. In the past decade, several strategies have been developed to eliminate these obstacles. These strategies result in strong macroscale graphene materials, such as graphene fibers with tensile strengths of over 3.4 GPa and sheets with tensile strengths of over 1.5 GPa, which have many practical applications. This Minireview summarizes the effective strategies for assembling graphene materials and compares their advantages and drawbacks. The preparation processes as well as the resulting fundamental mechanical properties and wide spectrum of electrical and magnetic properties are also discussed. Finally, our outlook for the future of this field is presented.
    | PDF | Supplementary Information
92. High-strength scalable graphene sheets by freezing stretch-induced alignment
    Sijie Wan, Ying Chen, Shaoli Fang, Shijun Wang, Zhiping Xu, Lei Jiang, Ray H. Baughman* and Qunfeng Cheng*
    Nature Materials, 2021, 20, 624–631. DOI: 10.1038/s41563-020-00892-2
    Abstract
    Efforts to obtain high-strength graphene sheets by near-room-temperature assembly have been frustrated by the misalignment of graphene layers, which degrades mechanical properties. While in-plane stretching can decrease this misalignment, it reappears when releasing the stretch. Here we use covalent and π–π inter-platelet bridging to permanently freeze stretch-induced alignment of graphene sheets, and thereby increase isotropic in-plane sheet strength to 1.55 GPa, in combination with a high Young’s modulus, electrical conductivity and weight-normalized shielding efficiency. Moreover, the stretch-bridged graphene
    sheets are scalable and can be easily bonded together using a commercial resin without appreciably decreasing the performance, which establishes the potential for practical applications.
    | PDF | Supporting Information

2020

79. Strong sequentially bridged MXene sheets
    Sijie Wan, Xiang Li, Yanlei Wang, Ying Chen, Xi Xie, Rui Yang, Antoni P. Tomsia, Lei Jiang and Qunfeng Cheng*
    PNAS, 2020, 117(44), 27154-27161. DOI:10.1073/pnas.2009432117
    Abstract
    Titanium carbide (Ti3C2Tx) MXene has great potential for use in aerospace and flexible electronics due to its excellent electrical conductivity and mechanical properties. However, the assembly of MXene nanosheets into macroscopic high-performance nanocomposites is challenging, limiting MXene’s practical applications. Here we describe our work fabricating strong and highly conductive MXene sheets through sequential bridging of hydrogen and ionic bonding. The ionic bonding agent decreases interplanar spacing and increases MXene nanosheet alignment, while the hydrogen bonding agent increases interplanar spacing and decreases MXene nanosheet alignment. Successive application of hydrogen and ionic bonding agents optimizes toughness, tensile strength, oxidation resistance in a humid environment, and resistance to sonication disintegration and mechanical abuse. The tensile strength of these MXene sheets reaches up to 436 MPa. The electrical conductivity and weight-normalized shielding efficiency are also as high as 2,988 S/cm and 58,929 dB∙cm2/g, respectively. The toughening and strengthening mechanisms are revealed by molecular-dynamics simulations. Our sequential bridging strategy opens an avenue for the assembly of other high-performance MXene nanocomposites.
    | PDF | Supplementary Information
80. Design Principles of High-Performance Graphene Films: Interfaces and Alignment
    Sijie Wan, Lei Jiang and Qunfeng Cheng*
    Matter, 2020, 3, 696-707. DOI:10.1016/j.matt.2020.06.023
    Abstract
    Graphene, the strongest, stiffest, and most conductive material known to date, would enable very strong, stiff, and highly conductive materials that would be better than what is available currently. These would be useful in a variety of fields, particularly flexible electronics and aerospace. Thus, to realize this potential, it is necessary to transfer these remarkable properties from graphene nanosheets into macroscopic graphene films. Nacre provides an inspiration for assembling graphene nanosheets into high-performance graphene films by constructing abundant interfacial interactions and a highly aligned structure. However, several issues in the assembly process,including intersheet bonding, dewrinkling, and alignment of graphene nanosheets, have been ignored in descriptions of previously reported macroscopic graphene films. This Review clarifies and compares the interface architecture of macroscopic graphene films described in previous reports. The representative orientation strategies are then summarized and the relationship between alignment and properties is discussed. Finally, perspectives and challenges are proposed to highlight the guidelines on how to construct high-performance graphene films in the future.
    | PDF | Supporting Information
81. Super-tough MXene-functionalized graphene sheets
    Tianzhu Zhou, Chao Wu, Yanlei Wang, Antoni P. Tomsia, Mingzhu Li, Eduardo Saiz, Shaoli Fang, Ray H. Baughman, Lei Jiang and Qunfeng Cheng*
    Nature Communications, 2020, 11, 2077. DOI: 10.1038/s41467-020-15991-6
    Abstract
    Flexible reduced graphene oxide (rGO) sheets are being considered for applications in portable electrical devices and flexible energy storage systems. However, the poor mechanical properties and electrical conductivities of rGO sheets are limiting factors for the development of such devices. Here we use MXene (M) nanosheets to functionalize graphene oxide platelets through Ti-O-C covalent bonding to obtain MrGO sheets. A MrGO sheet was crosslinked by a conjugated molecule (1-aminopyrene-disuccinimidyl suberate, AD). The incorporation of MXene nanosheets and AD molecules reduces the voids within the graphene sheet and improves the alignment of graphene platelets, resulting in much higher compactness and high toughness. In situ Raman spectroscopy and molecular dynamics simulations reveal the synergistic interfacial interaction mechanisms of Ti-O-C covalent bonding, sliding of MXene nanosheets, and π-π bridging. Furthermore, a supercapacitor based on our super-tough MXene-functionalized graphene sheets provides a combination of energy and power densities that are high for flexible supercapacitors.
    | PDF | Supplementary Information
82. Ultratough graphene-black phosphorus films
    Tianzhu Zhou, Hong Ni, Yanlei Wang, Chao Wu, Hao Zhang, Jianqi Zhang, Antoni P. Tomsia, Lei Jiang and Qunfeng Cheng*
    PNAS, 2020, 117, 8727-8735. DOI: 10.1073/pnas.1916610117
    Abstract
    Graphene-based films with high toughness have many promising applications, especially for flexible energy storage and portable electrical devices. Achieving such high-toughness films, however, remains a challenge. The conventional mechanisms for improving toughness are crack arrest or plastic deformation. Herein we demonstrate black phosphorus (BP) functionalized graphene films with record toughness by combining crack arrest and plastic deformation. The formation of covalent bonding P-O-C between BP and graphene oxide (GO) nanosheets not only reduces the voids of GO film but also improves the alignment degree of GO nanosheets, resulting in high compactness of the GO film. After further chemical reduction and pi-pi stacking interactions by conjugated molecules, the alignment degree of rGO nanosheets was further improved, and the voids in lamellar graphene film were also further reduced. Then, the compactness of the resultant graphene films and the alignment degree of reduced graphene oxide nanosheets are further improved. The toughness of the graphene film reaches as high as approximately 51.8 MJ m(-3), the highest recorded to date. In situ Raman spectra and molecular dynamics simulations reveal that the record toughness is due to synergistic interactions of lubrication of BP nanosheets, P-O-C covalent bonding, and pi-pi stacking interactions in the resultant graphene films. Our tough black phosphorus functionalized graphene films with high tensile strength and excellent conductivity also exhibit high ambient stability and electromagnetic shielding performance. Furthermore, a supercapacitor based on the tough films demonstrated high performance and remarkable flexibility.
    | PDF | Supporting Information
83. Inverse nacre-like epoxy-graphene layered nanocomposites with integration of high toughness and self-monitoring
    Jingsong Peng, Chuanjin Huang, Can Cao, Eduardo Saiz, Yi Du, Shixue Dou, Antoni P. Tomsia, Hanoch Daniel Wagner, Lei Jiang, and Qunfeng Cheng*
    Matter, 2020, 2, 220-232. DOI: 10.1016/j.matt.2019.08.013
    Abstract
    Epoxy nanocomposites have many promising applications in the fields of aerospace and aeronautics, as well as many others. Achieving tough epoxy nanocomposites remains a great challenge, however. One inspiration for improving the mechanical properties of epoxy nanocompositesisnacre,which hasremarkable fracture toughness for its layered ‘brick-and-mortar’ architecture. Inspired by this, we fabricated a lamellar graphene scaffold by the freeze-casting technique. An alternating-layered epoxy-graphene nanocomposite was made by infiltrating epoxy into this graphene scaffold. As our epoxy-graphene nanocomposite consists of ~99 wt % organic epoxy, in contrast to nacre containing ~96 wt % inorganic aragonite, we call it an ‘inverse nacre-like’ epoxy-graphene layered nanocomposite. It exhibits exceptional fracture toughness, 3.61 times that of pure epoxy, and demonstrates anisotropic conductivity due to the anisotropic graphene scaffold, which can be used to detect cracks. Our bioinspired strategy provides a promising approach to combine excellent mechanical properties with functional properties to fabricate high-performance nanocomposites.
    | PDF | Supplementary Information 1 | Supplementary Information 4

2019

74. A Butterfly-Inspired Hierarchical Light-Trapping Structure towards a High-Performance Polarization-Sensitive Perovskite Photodetector
    Yan Zhan, Yang Wang, Qunfeng Cheng, Chang Li, Kaixuan Li, Huizeng Li, Jingsong Peng, Bo Lu, Yu Wang, Yanlin Song, Lei Jiang and Mingzhu Li*
    Angew. Chem. Int. Ed., 2019, 58, 16456-16462. DOI: 10.1002/anie.201908743
    Abstract
    Extensive applications for photodetectors have led to demand for high-responsivity polarization-sensitive light detection. Inspired by the elaborate architecture of butterfly Papilio paris, a 1D nanograting bonded porous 2D photonic crystal perovskite photodetector (G-PC-PD) using a commercial DVD master and 2D crystalline colloidal arrays template was fabricated. The coupling effect from grating diffraction and reflection of the PC stopband renders the enhanced light harvesting of G-PC-PD. The porous scaffold and nanoimprinting process afford a highly crystalline perovskite film. White light responsivity and detectivity of G-PC-PD are up to 12.67 A W(-1) and 3.22×10(13) Jones (6 approximately 7 times that of a pristine perovskite photodetector). The highly ordered nanograting arrays of G-PC-PD enable polarization-sensitive light detection with a rate of -0.72 nA deg(-1) . This hierarchical perovskite integrated nanograting and 2D PC architecture opens a new avenue to high-performance optoelectronic devices.
    | PDF | Supplementary Information
75. Moiré-Potential-Induced Band Structure Engineering in Graphene and Silicene
    Mengting Zhao, Jincheng Zhuang,* Qunfeng Cheng, Weichang Hao and Yi Du*
    Small, 2019, 1903769. DOI: 10.1002/smll.201903769
    Abstract
    A moiré pattern results from the projection of one periodic pattern to another with relative lattice constant or misalignment and provides great periodic potential to modify the electronic properties of pristine materials. In this Review, recent research on the effect of the moiré superlattice on the electronic structures of graphene and silicene, both of which possess a honeycomb lattice, is focused on. The moiré periodic potential is introduced by the interlayer interaction to realize abundant phenomena, including new generation of Dirac cones, emergence of Van Hove singularities (vHs) at the cross point of two sets of Dirac cones, Mott-like insulating behavior at half-filling state, unconventional superconductivity, and electronic Kagome lattice and flat band with nontrivial edge state. The role of interlayer coupling strength, which is determined by twist angle and buckling degree, in these exotic properties is discussed in terms of both the theoretical prediction and experimental measurement, and finally, the challenges and outlook for this field are discussed.
76. Near-Infrared-Driven Photocatalysts: Design, Construction, and Applications
    Li Wang, Xun Xu,* Qunfeng Cheng,* Shi Xue Dou, Yi Du*
    Small, 2019, 1904107. DOI: 10.1002/smll.201904107
    Abstract
    Photocatalysts, which utilize solar energy to catalyze the oxidation or reduction half reactions, have attracted tremendous interest due to their great potential in addressing increasingly severe global energy and environmental issues. Solar energy utilization plays an important role in determining photocatalytic efficiencies. In the past few decades, many studies have been done to promote photocatalytic efficiencies via extending the absorption of solar energy into near-infrared (NIR) light. This Review comprehensively summarizes the recent progress in NIR-driven photocatalysts, including the strategies to harvest NIR photons and corresponding photocatalytic applications such as the degradation of organic pollutants, water disinfection, water splitting for H2 and O2 evolution, CO2 reduction, etc. The application of NIR-active photocatalysts employed as electrocatalysts is also presented. The subject matter of this Review is designed to present the relationship between material structure and material optical properties as well as the advantage of material modification in photocatalytic reactions. It paves the way for future material design in solar energy–related fields and other energy conversion and storage fields.
    | PDF
77. Ultrastrong graphene films via long-chain π-bridging
    Sijie Wan, Ying Chen, Yanlei Wang, Guangwen Li, Guorui Wang, Luqi Liu, Jianqi Zhang, Yuzhou Liu, Zhiping Xu, Antoni, P. Tomsia, Lei Jiang, and Qunfeng Cheng*
    Matter, 2019, 1, 389-401. DOI: 10.1016/j.matt.2019.04.006
    Abstract
    Converting natural graphite to high-performance graphene films is very attractive due to graphite’s abundance. However, this conversion is challenging to do inexpensively and under ambient conditions. One of themajor challenges is how to design the interface between adjacent graphene nanosheets to integrate high strength, high toughness, and high conductivity into graphene films. Here, we demonstrate that a long-chain p-p bonding agent can bridge reduced graphene oxide nanosheets into ultrastrong, supertough, and highly conductive graphene films. The strain dependence of Raman frequency shift and molecular dynamics simulations together reveal the strengthening and toughening mechanisms. Additionally, the long-chain p-bridging induces substantial improvement in the graphene nanosheet alignment. The tensile strength and toughness are 1,054 MPa and 36 MJ/m3, surpassing those of reported graphene films. Meanwhile, the electrical conductivity reaches 1,192 S/cm, comparable with high-temperature annealed graphene films. The bioinspired strategy opens an avenue for the assembly of nanoscale building blocks into high-performance films.
    | PDF and Supplemental Information
78. Ultra‐tough inverse artificial nacre based on epoxy‐graphene by freeze‐casting
    Chuanjin Huang, Jingsong Peng, Sijie Wan, Yi Du, Shixue Dou, Hanoch Daniel Wagner, Antoni P. Tomsia, Lei Jiang, and Qunfeng Cheng*
    Angew. Chem. Int. Ed., 2019, 58, 7636-7640. DOI: 10.1002/anie.201902410
    Abstract
    Inspiration is drawn from natural nacre to fabricate ultra‐tough inverse artificial nacre based on epoxy‐graphene. As shown by Q. F. Cheng et al. in their Communication (DOI: 10.1002/anie.201902410), many graphene oxide nanosheets can be manipulated into lamellar scaffolds, similar to nacre‐like structure through freeze‐casting technique. The inverse nacre‐inspired concept provides a platform for the fabrication of high‐performance bulk nanocomposites.
    | PDF | Supplementary Information
79. Enhancing the strength, toughness, and electrical conductivity of twist-spun carbon nanotube yarns by π bridging
    Xiumin Liang, Yuan Gao, Jianli Duan, Zunfeng Liu, Shaoli Fang, Ray H. Baughman, Lei Jiang, Qunfeng Cheng*
    Carbon, 2019, 150, 268-274. DOI:10.1016/j.carbon.2019.05.023
    Abstract
    The weak interfacial interactions between carbon nanotube (CNT) always results in low stress load transfer efficiency in CNT yarns, herein we fabricated strong, highly conducting CNT yarns at room temperature using molecules having aromatic end groups, π bridging neighboring CNTs. The resulting CNT yarns have high tensile strength with 1697 ± 24 MPa, toughness with 18.6 ± 1.6 MJ/m3, and electrical conductivity with 656.2 S/cm, which are 3.9, 2.5, and 3.5 times, respectively, as high as that of the neat CNT yarn. The specific tensile strength of the resulting CNT yarn is higher than that for previously reported CNT yarns fabricated at room temperature, even that for some CNT yarns fabricated using corossive environments or extreme temperature. This π bridging strategy provides a promising avenue for fabricating high performance CNT yarns under ambient conditions.
    | PDF | Supplementary Information
80. Ultratough nacre-inspired epoxy–graphene composites with shape memory properties
    Chuanjin Huang, Jingsong Peng, Yiren Cheng, Qian Zhao, Yi Du, Shixue Dou, Antoni P. Tomsia, Hanoch Daniel Wagner, Lei Jiang, Qunfeng Cheng*
    Journal of Materials Chemistry A, 2019, 7, 2787-2794. DOI: 10.1039/c8ta10725d
    Abstract
    Shape memory polymers are widely used in industrial applications. Despite extensive and continuous research studies, it is still a great challenge to improve the mechanical properties without affecting their shape memory properties. One approach to improving them is to seek inspiration from natural materials that exhibit superior performance and provide an infinite source of design guidelines. Inspired by the hierarchical architecture of nacre, we have prepared nacre-like shape memory epoxy–graphene composites via freeze-casting, a technique to create lamellar materials with complex hierarchical microstructures. Perpendicular to the lamellar direction, the fracture toughness of our composites is
    2.5 times that of the epoxy matrix, due to the synergy of extrinsic toughening mechanisms combining crack deflection, crack branching, crack bridging, and friction between the layered platelets. We achieved high damage-tolerance in our composites by having some degree of plasticity to relax stresses in an epoxy layer. The shape memory properties can be activated using external heating. Due to the electrical conductivity of graphene, we have also achieved electro-active shape memory composites. Our approach suggests an avenue for producing bioinspired shape memory composites with good mechanical and multi-functional properties by utilizing the design principles and strengthening/ toughening mechanisms active in nacre and other biological materials.
    | PDF | Supplementary Information
81. Strong bioinspired HPA-rGO nanocomposite films via interfacial interactions for flexible supercapacitors
    Chao Wu, Tianzhu Zhou, Yi Du, Shixue Dou, Hao Zhang*, Lei Jiang, Qunfeng Cheng*
    Nano Energy, 2019, 58, 517-527. DOI:10.1016/j.nanoen.2019.01.055
    Abstract
    Flexible supercapacitors with excellent performance are needed to meet the increasing demand for wearable and flexible electronics. The challenge remains to design exceptionally flexible supercapacitors with remarkable electrochemical properties. Natural nacre shows outstanding fracture toughness due to its alternating inorganic and organic layered structure and abundant interfacial interactions, providing an inspiration for designing flexible supercapacitors. Herein, we demonstrated nacre-inspired flexible supercapacitors via synergistic interfacial interactions of π-π conjugated bonds, hydrogen bonding, and electrostatic interaction between halloysite (HA)-polyaniline (PANI) nanocomposites and graphene oxide (GO) nanosheets. The resultant nacre-inspired HPA-rGO nanocomposite films demonstrate strong tensile strength (351.9 MPa), high electrical conductivity (397.0 S cm−1), and long cycle life with ~85% of capacitance retention after 10,000 cycles. Furthermore, the assembled all-solid-state supercapacitors (ASSSs) based on bioinspired HPA-rGO electrodes can not only display extraordinary flexibility with no decay of capacitance behavior after 5000 bending cycles, but also deliver remarkable mass energy density up to 16.3 Wh kg−1, outperforming other flexible graphene-based supercapacitors. This nacre-inspired strategy for designing flexible electrodes provides an avenue for the next-generation power source in the fields of aerospace and smart wearable electronics.
    | PDF | Supplementary Information

2018

66. Ultratough Bioinspired Graphene Fiber via Sequential Toughening of Hydrogen and Ionic Bonding
    Xiaohui Wang, Jingsong Peng, Yuanyuan Zhang, Mingzhu Li, Eduardo Saiz, Antoni P. Tomsia, Qunfeng Cheng*
    ACS Nano, 2018, 12, 12638-12645. DOI:10.1021/acsnano.8b07392
    Abstract
    Graphene-based fibers synthesized under ambient temperature have not achieved excellent mechanical properties of high toughness or tensile strength compared with those synthesized by hydrothermal strategy or graphitization and annealing treatment. Inspired by the relationship between organic/inorganic hierarchical structure, interfacial interactions, and moderate growth temperature of natural nacre, we fabricate an ultratough graphene fiber via sequential toughening of hydrogen and ionic bonding through a wet-spinning method under ambient temperature. A slight amount of chitosan is introduced to form hydrogen bonding with graphene oxide nanosheets, and the ionic bonding is formed between graphene oxide nanosheets and divalent calcium ions. The optimized sequential toughening of hydrogen and ionic bonding results in an ultratough graphene fiber with toughness of 26.3 MJ/m(3) and ultimate tensile strength of 743.6 MPa. Meanwhile, the electrical conductivity of the resultant graphene fiber is as high as 179.0 S/cm. This kind of multifunctional graphene fiber shows promising applications in photovoltaic wires, flexible supercapacitor electrodes, wearable electronic textiles, fiber motors, etc. Furthermore, the strategy of sequential toughening of hydrogen and ionic bonding interactions also offers an avenue for constructing high-performance graphene-based fibers in the near future.
    | PDF | Supplementary Information
67. Synergistic reinforcing effect from graphene and carbon nanotubes
    Xiumin Liang, Qunfeng Cheng*
    Composites Communications, 2018, 10, 122-128. DOI:10.1016/j.coco.2018.09.002
    Abstract
    Carbon nanomaterials show excellent physicochemical properties, especially for carbon nanotubes (CNTs) and graphene nanosheets. A large amount of bioinspired hybrid materials based on graphene/CNTs have been reported. The mechanical and electrical properties of resultant carbon nanomaterials based hybrid materials have been dramatically improved, indicating the synergistic effect between carbon nanotubes and graphene. In fact, the synergistic effect always plays a key role in the natural materials such as nacre and bone, and bioinspired materials based on carbon nanomaterials. Herein, this mini-review summarizes recent progress in synergistic effect from CNTs and graphene in the bioinspired hybrid materials and also make the perspective of the synergistic reinforcing effect from CNTs and graphene in enhancing the performance of carbon nanomaterialsbased nanocomposites.
    | PDF
68. Bioinspired Supertough Graphene Fiber through Sequential Interfacial Interactions
    Yuanyuan Zhang, Jingsong Peng, Mingzhu Li, Eduardo Saiz, Stephan E. Wolf, Qunfeng Cheng*
    ACS Nano, 2018, 12, 8901-8908. DOI:10.1021/acsnano.8b04322
    Abstract
    Natural nacre exhibits extraordinary functional and structural diversity, combining high strength and toughness. The mechanical properties of nacre are attributed to (i) a highly arranged hierarchical layered structure of inorganic minerals (95 vol %) containing a small amount only of organic materials (5 vol %), (ii) abundant synergistic interfacial interactions, and (iii) formation under ambient temperature. Herein, inspired by these three design principles originating from natural nacre, the supertough bioinspired graphene-based nanocomposite fibers (BGNFs) are prepared under room temperature via sequential interfacial interactions of ionic bonding and pi-pi interactions. The resultant synergistic effect leads to a super toughness of 18.7 MJ m-3 as well as a high tensile strength of 740.1 MPa. In addition, the electrical conductivity of these supertough BGNFs is as high as 384.3 S cm-1. They can retain almost 80% of this conductivity even after 1000 cycles of loading-unloading testing, which makes these BGNFs promising candidates for application in flexible and stable electrical devices, such as strain sensors and actuators.
    | PDF | Supplementary Information
69. Strong, Conductive, Foldable Graphene Sheets by Sequential Ionic and pi Bridging
    Sijie Wan, Shaoli Fang, Lei Jiang, Qunfeng Cheng*, Ray H. Baughman*
    Adv. Mater., 2018, e1802733-e1802733. DOI:10.1002/adma.201802733
    Abstract
    The goal of this work is to develop an inexpensive low-temperature process that provides polymer-free, high-strength, high-toughness, electrically conducting sheets of reduced graphene oxide (rGO). To develop this process, we have evaluated the mechanical and electrical properties resulting from the application of an ionic bonding agent (Cr3+ ), a pi-pi bonding agent comprising pyrene end groups, and their combinations for enhancing the performance of rGO sheets. When only one bonding agent was used, the pi-pi bonding agent is much more effective than the ionic bonding agent for improving both the mechanical and electrical properties of rGO sheets. However, the successive application of ionic bonding and pi-pi bonding agents maximizes tensile strength, toughness, long-term electrical stability in various corrosive solutions, and resistance to mechanical abuse and ultrasonic dissolution. Using a combination of ionic bonding and pi-pi bonding agents, high tensile strength (821 MPa), high toughness (20 MJ m-3 ), and electrical conductivity (416 S cm-1 ) were obtained, as well as remarkable retention of mechanical and electrical properties during ultrasonication and mechanical cycling by both sheet stretch and sheet folding, suggesting high potential for applications in aerospace and flexible electronics.
    | PDF | Supplementary Information
70. Role of Interface Interactions in the Construction of GO-Based Artificial Nacres
    Sijie Wan, and Qunfeng Cheng*
    Adv. Mater. Interfaces, 2018, 1800107. DOI:10.1002/admi.201800107
    Abstract
    The hierarchical interfacial architecture of nacre inspires the fabrication of
    novel high performance graphene-based nanocomposites. Graphene has
    great promise for applications in aerospace and especially for flexible electronic devices, etc., due to its remarkable mechanical and electrical properties.Thus, it is significant to summarize the role of interface interactions in the construction of nacre-inspired graphene-based nanocomposites, which is the distinctive characteristic and important scientific progress of the review. This review first makes a comparison for the interfacial architecture of above biological materials and finds inspiration from nacre to design the interface in graphene-based nanocomposites, which contains single interface interaction, synergistic interface interactions, and synergistic building blocks. Then, the focus is attached to the effect of different interfacial design strategies on the mechanical and electrical properties of state-of-the-art GO-based artificial nacres (GANs), including 1D fibers, 2D films, and 3D bulk materials. Additionally, the multifunctional GANs with such functions as fatigue resistance, fire retardant property, and smart nanogating, etc. are also discussed. Moreover, some potential applications and corresponding challenges and solutions of GANs are detailedly summarized. Finally, from the views of theoretical simulation and experimental research, a perspective on the roadmap of GANs in the future is also proposed.
    | PDF
71. Multiple Synergistic Toughening Graphene Nanocomposites through Cadmium Ions and Cellulose Nanocrystals
    Yuan Gao, Hanjie Xu, and Qunfeng Cheng*
    Adv. Mater. Interfaces, 2018, 1800145. DOI:10.1002/admi.201800145
    Abstract
    Robust and functional graphene-based nanocomposites are attractive in flexible electric devices. Herein, a strong and conductive bioinspired graphenebased
    nanocomposite is demonstrated via multiple synergistic toughening effect from graphene oxide (GO), cellulose nanocrystals (CNC), and cadmium ion (Cd2+). The multiple synergistic toughening effect can be realized from building blocks of 2D GO nanosheets and 1D CNC, interface interactions of hydrogen bonding from CNC and ionic bonding from Cd2+, resulting in
    integrated graphene-based nanocomposites with high strength, and toughness as well as electrical conductivity. This ternary synthetic graphene-based nanocomposite possessing outstanding physical properties provides a clear vision in the application of flexible electric devices. Furthermore, this bioinspired strategy could also serve as a guideline for the development of highperformance graphene-based nanocomposites in the future.
    | PDF | Supplementary Information
72. Glycera-Inspired Synergistic Interfacial Interactions for Constructing Ultrastrong Graphene-Based Nanocomposites
    Yiren Cheng, Jingsong Peng, Hanjie Xu, and Qunfeng Cheng*
    Adv. Funct. Mater., 2018, 1800924. DOI:10.1002/adfm.201800924
    Abstract
    The interest in bioinspired graphene-based nanocomposites (BGBNs) is rising recently due to their exceptional mechanical properties as well as high electrical conductivities. Numerous works have suggested that the synergistic interfacial design of ionic bonding (IB) co-working with other interfacial interactions effectively improves the mechanical properties of BGBNs. However, as the ions are conventionally chelated with graphene oxide (GO) nanosheets, the relatively weak and short interlayered IB may hinder the load transfer between GO nanosheets leading to poor synergistic effects. Herein, inspired by the jaw of Glycera, the synergistic effect is further amplified via special IB, which stiffens the organic component. Compared with the traditional IB, the metal–ligand coordinate bonding by copper ions that is used in this work and originates from Glycera, selectively cross-links the chitosan chains. This Glycera-inspired synergistic effect strategy boosts record tensile strength to an extraordinary value of 868.6 MPa, five times higher than that of the pure reduced graphene oxide film. The additional high electrical conductivity enables applications in many fields such as flexible energy devices, supercapacitors, and other electronic devices.
    
    | PDF|Supplementary Information
73. Sequentially bridged graphene sheets with high strength, toughness, and electrical conductivity
    Sijie Wan, Yuchen Li, Jiuke Mu, Ali E. Aliev, Shaoli Fang, Nicholas A. Kotov, Lei Jiang, Qunfeng Cheng* and Ray H. Baughman*
    PNAS, 2018, 115, 5359-5364. DOI:10.1073/pnas.1719111115
    Abstract
    We here show that infiltrated bridging agents can convert inexpensively fabricated graphene platelet sheets into high-performance materials, thereby avoiding the need for a polymer matrix. Two types of bridging agents were investigated for interconnecting graphene sheets, which attach to sheets by either π–π bonding or covalent bonding. When applied alone, the π–π bonding agent is most effective. However, successive application of the optimized ratio of π–π bonding and covalent bonding agents provides graphene sheets with the highest strength, toughness, fatigue resistance, electrical conductivity, electromagnetic interference shielding efficiency, and resistance to ultrasonic dissolution. Raman spectroscopy measurements of stress transfer to graphene platelets allow us to decipher the mechanisms of property improvement. In addition, the degree of orientation of graphene platelets increases with increasing effectiveness of the bonding agents, and the interlayer spacing increases. Compared with other materials that are strong in all directions within a sheet, the realized tensile strength (945 MPa) of the resin-free graphene platelet sheets was higher than for carbon nanotube or graphene platelet composites, and comparable to that of commercially available carbon fiber composites. The toughness of these composites, containing the combination of π–π bonding and covalent bonding, was much higher than for these other materials having high strengths for all in-plane directions, thereby opening the path to materials design of layered nanocomposites using multiple types of quantitatively engineered chemical bonds between nanoscale building blocks.
    | PDF|Supplementary Information
74. A new strategy for air-stable black phosphorus reinforced PVA nanocomposites
    Hong Ni, Xiaochen Liu, Qunfeng Cheng*
    J. Mater. Chem. A, 2018, 6, 7142-7147. DOI:10.1039/c8ta00113h
    Abstract
    Black phosphorus (BP) has attracted extensive scientific interest due to its particularly unique electrical properties. In recent years, an increasing number of researchers have shown great interest in the electrical and optical performance of BP in practical applications. However, the exploration of its mechanical properties is rare because BP tends to be oxidized in the atmosphere. In this study, BP nanosheets as two-dimensional nanofillers were used to reinforce the poly(vinyl alcohol) (PVA) matrix. The resultant BP-PVA nanocomposites presented excellent air-stability due to the formation of saturated P-O bonds outside the PVA-coated BP nanosheets. In addition, friction between the BP nanosheets and the PVA matrix led to increased strength, toughness, and modulus, which was confirmed by Raman spectrum analysis. The maximum tensile strength is up to 316.9 +/- 12.1 MPa, which is 1.9-times higher than that of a pure PVA film. This strengthening effect of BP in the PVA matrix is superior to that of graphene reinforced PVA nanocomposites with similar content of graphene, indicating a favorite mechanical increase of BP in nanocomposites.
    | PDF|Supplementary Information
75. Smart Nacre-inspired Nanocomposite
    Jingsong Peng and Qunfeng Cheng*
    Chemphyschem, 2018, 19, 1-8. DOI:10.1002/cphc.201701390
    PDF
76. Bioinspired graphene-based nanocomposites via ionic interfacial interactions
    Shanshan Gong, and Qunfeng Cheng*
    Composites Communications, 2018, 7, 16-22. DOI: 10.1016/j.coco.2017.12.002
    Abstract
    In nature, small amount of metal ions play a critical role in improving mechanical properties, such as the jaws of marine polychaete Nereis and Glycera. Recently, the multivalent cations metals have been successfully introduced to enhance the interfacial strength of graphene based-nanocomposites through forming ionic crosslinking networks with graphene oxide (GO) nanosheets by coordination. Combination with other interfacial interactions, the synergistic effect was constructed in the resultant bioinspired nanocomposites, leading to outstanding integrated performance, including thermal, electrical, fatigue resistant and mechanical properties. These excellent properties make this bioinspired graphene-based nanocomposites to be great candidates for applications in many fields, for example, flexible electronics devices, artificial muscles, supercapacitors, and aerospace.
    | PDF

2017

55. Bioinspired graphene membrane with temperature tunable channels for water gating and molecular separation
    Jingchong Liu, Nü Wang*, Li-Juan Yu, Amir Karton, Wen Li, Weixia Zhang, Fengyun Guo, Lanlan Hou, Qunfeng Cheng, Lei Jiang, David A. Weitz and Yong Zhao*
    Nat. Commun., 2017, 8, 2011. DOI:10.1038/s41467-017-02198-5
    Abstract
    Smart regulation of substance permeability through porous membranes is highly desirable for membrane applications. Inspired by the stomatal closure feature of plant leaves at relatively high temperature, here we report a nano-gating membrane with a negative temperature-response coefficient that is capable of tunable water gating and precise small molecule separation. The membrane is composed of poly(N-isopropylacrylamide) covalently bound to graphene oxide via free-radical polymerization. By virtue of the temperature tunable lamellar spaces of the graphene oxide nanosheets, the water permeance of the membrane could be reversibly regulated with a high gating ratio. Moreover, the space tunability endows the membrane with the capability of gradually separating multiple molecules of different sizes. This nano-gating membrane expands the scope of temperature-responsive membranes and has great potential applications in smart gating systems and molecular separation.
    | PDF | Supplementary Information
56. High Performance Nanocomposites Inspired by Nature
    Jingsong Peng, and Qunfeng Cheng*
    Adv. Mater., 2017, 29, 1702959. DOI:10.1002/adma.201702959
    Abstract
    Natural materials, including nacre, bone, and the lobster cuticle, exhibit excellent mechanical properties, combining high strength and toughness. Such materials have the added benefit of being light in weight. These advantageous features are due to such natural materials’ orderly hierarchical architectures and abundant interface interactions. How to utilize these design principles created by nature to fabricate high-performance bioinspired nanocomposites remains a great research challenge. A logical roadmap for developing these nanocomposites can be described as “discovery, invention, and creation.” Here, the discovery of the relationship between natural materials’ design principles and such materials’ extraordinary mechanical properties is discussed. Then, the invention of bioinspired strategies for mimicking natural materials is considered and representative strategies addressed. Next, the creation of multifunctional nanocomposites is discussed and bioinspired nanocomposites, including fiber nanocomposites, 2D film nanocomposites, and 3D bulk nanocomposites reviewed. Finally, a perspective and outlook for future directions in making bioinspired nanocomposites is provided to offer inspiration to the community and a clear vision for future research.
    | PDF
57. Fatigue Resistant Bioinspired Graphene-Based Nanocomposites
    Sijie Wan, and Qunfeng Cheng*
    Adv. Funct. Mater., 2017, 27, 1703459. DOI: 10.1002/adfm.201703459
    Abstract
    Graphene is an attractive building block for constructing functional materials of flexible electronic devices, due to its extraordinary mechanical and electrical properties. Up to now, large amounts of high-performance graphenebased nanocomposites are fabricated. However, the fatigue behavior of graphene-based nanocomposites, a key parameter for flexible electronic devices, is rarely investigated. According to the fatigue mechanisms of thermosetting polymer composites, the fatigue resistance of graphene-based nanocomposites can be significantly improved by effectively restricting the crack growth. Natural nacre demonstrates unique multisuppression of crack propagation, which is attributed to its sophisticated interfacial architecture over multiple length scales, resulting in remarkable fracture toughness. The crack suppression mechanisms corresponding to different interfacial design strategies within bioinspired graphene-based nanocomposites (BGBNs) are summarized in this feature article. The static mechanical properties, electrical conductivity, and fatigue resistance of these BGBNs are compared and discussed. The synergistic effect from various interfacial interactions and building blocks is highlighted to serve as the guidance for constructing novel fatigue-resistant BGBNs. The promising applications of fatigue-resistant BGBNs in flexible electronic devices are reviewed, and several challenges and corresponding solutions are proposed. The perspective of fatigue-resistant BGBNs for fundamental research and commercial application is depicted.
    | PDF
58. Freeze Casting for Assembling Bioinspired Structural Materials
    Qunfeng Cheng, Chuanjin Huang, and Antoni P. Tomsia*
    Adv. Mater., 2017, 1703155. DOI:10.1002/adma.201703155
    Abstract
    Nature is very successful in designing strong and tough, lightweight materials. Examples include seashells, bone, teeth, fish scales, wood, bamboo, silk, and many others. A distinctive feature of all these materials is that their properties are far superior to those of their constituent phases. Many of these natural materials are lamellar or layered in nature. With its “brick and mortar” structure, nacre is an example of a layered material that exhibits extraordinary physical properties. Finding inspiration in living organisms to create bioinspired materials is the subject of intensive research. Several processing techniques have been proposed to design materials mimicking natural materials, such as layer-by-layer deposition, self-assembly, electrophoretic deposition, hydrogel casting, doctor blading, and many others. Freeze casting, also known as ice-templating, is a technique that has received considerable attention in recent years to produce bioinspired bulk materials. Here, recent advances in the freeze-casting technique are reviewed for fabricating lamellar scaffolds by assembling different dimensional building blocks, including nanoparticles, polymer chains, nanofibers, and nanosheets. These lamellar scaffolds are often infiltrated by a second phase, typically a soft polymer matrix, a hard ceramic matrix, or a metal matrix. The unique architecture of the resultant bioinspired structural materials displays excellent mechanical properties. The challenges of the current research in using the freeze-casting technique to create materials large enough to be useful are also discussed, and the technique’s promise for fabricating high-performance nacre-inspired structural materials in the future is reviewed.
    | PDF
59. Fatigue Resistant Bioinspired Composite from Synergistic Two-Dimensional Nanocomponents
    Sijie Wan, Qi Zhang, Xiaohang Zhou, Dechang Li, Baohua Ji, Lei Jiang, and Qunfeng Cheng*
    ACS Nano, 2017, 11, 7074‐7083. DOI:10.1021/acsnano.7b02706
    Abstract
    Portable and wearable electronics require much more flexible graphene-based electrode with high fatigue life, which could repeatedly bend, fold, or stretch without sacrificing its mechanical properties and electrical conductivity. Herein, a kind of ultrahigh fatigue resistant graphene-based nanocomposite via tungsten disulfide (WS2) nanosheets is synthesized by introducing a synergistic effect with covalently cross-linking inspired by the orderly layered structure and abundant interfacial interactions of nacre. The fatigue life of resultant graphene-based nanocomposites is more than one million times at the stress level of 270 MPa, and the electrical conductivity can be kept as high as 197.1 S/cm after 1.0 × 105 tensile testing cycles. These outstanding properties are attributed to the synergistic effect from lubrication of WS2 nanosheets for deflecting crack propagation, and covalent bonding between adjacent GO nanosheets for bridging crack, which is verified by the molecular dynamics (MD) simulations. The WS2 induced synergistic effect with covalent bonding offers a guidance for constructing graphene-based nanocomposites with high fatigue life, which have great potential for applications in flexible and wearable electronic devices, etc.
    | PDF | Supplementary Information
60. Superior Fatigue Resistant Bioinspired Graphene-Based Nanocomposite via Synergistic Interfacial Interactions
    Sijie Wan, Feiyu Xu, Lei Jiang, and Qunfeng Cheng*
    Adv. Funct. Mater., 2017, 27, 1605636. DOI:10.1002/adfm.201605636
    Abstract
    Excellent fatigue resistance is a prerequisite for flexible energy devices to achieve high and stable performance under repeated deformation state. Inspired by the sophisticated interfacial architecture of nacre, herein a super fatigue-resistant graphene-based nanocomposite with integrated high tensile strength and toughness through poly(dopamine)-nickel ion (Ni2+) chelate architecture that mimics byssal threads is demonstrated. These kind of synergistic interfacial interactions of covalent and ionic bonding effectively suppress the crack propagation in the process of fatigue testing, resulting in superhigh fatigue life of this bioinspired graphene-based nanocomposite (BGBN). In addition, the electrical conductivity is well kept after fatigue testing. The proposed synergistic interfacial interactions could serve as a guideline for fabricating high-performance multifunctional BGBNs with promising applications in flexible energy devices, such as flexible electrodes for supercapacitors and lithium batteries, etc.
    | PDF | Supplementary Information
61. Thermochromic Artificial Nacre Based on Montmorillonite
    Jingsong Peng, Yiren Cheng, Antoni P. Tomsia, Lei Jiang, and Qunfeng Cheng*
    ACS Appl. Mater. Interfaces, 2017, 9, 24993‐24998. DOI:10.1021/acsami.7b07953
    Abstract
    Nacre-inspired nanocomposites have attracted a great deal of attention in recent years because of their special mechanical properties and universality of the underlying principles of materials engineering. The ability to respond to external stimuli will augment the high toughness and high strength of artificial nacre-like composites and open new technological horizons for these materials. Herein, we fabricated robust artificial nacre based on montmorillonite (MMT) that combines robustness with reversible thermochromism. Our artificial nacre shows great potential in various fields such as aerospace and sensors and opens an avenue to fabricate artificial nacre responsive to other external stimuli in the future.
    
    | PDF | Supplementary Information
62. Robust Bioinspired Graphene Film via π–π Cross-linking
    Hong Ni, Feiyu Xu, Antoni P. Tomsia, Eduardo Saiz, Lei Jiang, and Qunfeng Cheng*
    ACS Appl. Mater. Interfaces, 2017, 9, 24987‐24992. DOI:10.1021/acsami.7b07748
    Abstract
    Graphene composite films inspired by nacre are the subject of ongoing research efforts to optimize their properties for applications in flexible energy devices. Noncovalent interactions do not cause interruption of the delocalized conjugated π-electron system, thus preserving graphene’s excellent properties. Herein, we synthesized a conjugated molecule with pyrene groups on both ends of a long linear chain (AP-DSS) from 1-aminopyrene (AP) and disuccinimidyl suberate (DSS). The AP-DSS molecules are used to cross-link adjacent graphene nanosheets via π–π interfacial interactions to improve properties of graphene films. The tensile strength and toughness of resultant graphene films were 4.1 and 6.4 times higher, respectively, than that of pure rGO film. More remarkably, the electrical conductivity showed a simultaneous improvement, which is rare to be achieved in other kinds of covalent or noncovalent functionalization. Such integration demonstrates the advantage of this work to previously reported noncovalent functionalization of graphene.
    | PDF | Supplementary Information
63. Learning from nacre: Constructing polymer nanocomposites
    Chuanjin Huang, and Qunfeng Cheng*
    Compos. Sci. Technol., 2017, 150, 141‐166. DOI:http://dx.doi.org/10.1016/j.compscitech.2017.07.021
    Abstract
    Due to the small size and special physical properties of nanometer materials, polymer nanocomposites, combined nanoscale reinforcements with polymer matrix, possess outstanding mechanical properties and functional performances, which play a key role in many fields, especially for application in fields of industry and aerospace. However, poor dispersion and weak interfacial interactions are the critical factors that restrict the great improvement in performance of polymer nanocomposites. Although these issues have been solved in some extent via various methods, such as surfactant adsorption, polymer wrapping, surface modification, it still remains a great challenge for achieving high performance polymer
    nanocomposites as theoretically expected. Nacre, with 95% (volume fraction) inorganic calcium carbonate and 5% (volume fraction) biopolymers, is a typical binary cooperative complementary material system with hard inorganic component and soft organic matrix. Its typical “brick-and-mortar” hierarchical micro/nano-scale structure provides an excellent guideline for constructing polymer nanocomposites. It skillfully overcomes the bottleneck of traditional approaches for fabricating polymer nanocomposites, such as poor dispersion, low loading, and weak interfacial interactions. Recently, we have successfully demonstrated the bioinspired concept is a successful approach for constructing high performance polymer nanocomposites based on different reinforcement fillers, such as nanoclay, carbon nanotubes, and graphene. The resultant bioinspired polymer nanocomposites (BPNs) show layered hierarchical micro/nano-scale structure and outstanding mechanical properties. This feature article reviews our group’s work and other groups’ research results on BPNs in recent years, and discuss the advantages of BPNs through comparing with traditional methods, as shown in Fig. 1, including: i) Bioinspired assembly approaches for achieving the homogeneous dispersion and layered structure of reinforcement fillers in polymer matrix, such as layer-by-layer, infiltration, evaporation, freeze casting.; ii) various approaches for designing interfacial interactions; iii) the effect of synergy on the performance of BPNs; iv) representative applications of BPNs, such as energy storage devices, filter, sensors. Finally, this feature article also focuses on a perspective of BPNs, commenting on whether the bioinspired concept is viable and practical for polymer nanocomposites, and on what has been achieved to date. Most importantly, a roadmap of BPNs for near future will be depicted, including integrated mechanical properties and functions, intelligent properties, etc.
    | PDF
64. Synergistically toughening nacre-like graphene nanocomposites via gel-film transformation
    Shanshan Gong, Qi Zhang, Ruliang Wang, Lei Jiang, and Qunfeng Cheng*
    J. Mater. Chem. A, 2017, 5, 16386-16392. DOI:10.1039/C7TA03535G
    Abstract
    The gold standard of natural nacre provides the inspiration for assembling bioinspired nanocomposites. Herein, the gel-film transformation method, a feasible and economical strategy, was applied to fabricate flexible, large-area, and hierarchical porous graphene oxide (GO)-based nanocomposites with excellent properties. In this study, the GO-polymer nanocomposite hydrogels could be transformed into nanocomposite films with hierarchically laminated structures via the evaporation self-assembly technique, followed by introduction of ionic cross-linking into the nanocomposite films. The obtained bioinspired nanocomposites, with synergistic effect originating from hydrogen bonds and ionic bonds, have an excellent tensile strength of 475.2 +/- 13.0 MPa and a toughness of 6.6 +/- 0.3 MJ m-3, as well as a high electrical conductivity of 297.1 S cm-1. Therefore, this type of strong integrated nacre-like graphene nanocomposites have great potential applications in aerospace and flexible supercapacitor electrodes.
    
    | PDF | Supplementary Information
65. Mimicking Nacre by Ice Templating
    Qunfeng Cheng, and Lei Jiang*
    Angew. Chem. Int. Ed., 2017, 56, 934-935. DOI:10.1002/anie.201610176
    PDF
66. Learning from nature: constructing high performance graphene-based nanocomposites
    Shanshan Gong, Hong Ni, Lei Jiang, and Qunfeng Cheng*
    ‎Mater. Today, 2017, 20, 210-219. DOI: 0.1016/j.mattod.2016.11.002
    Abstract
    After billions of years of evolution, natural materials, such as bamboo, bone, and nacre, show unique mechanical properties, due to their intrinsic hierarchical micro/nanoscale architecture and abundant interfacial interactions. This relationship between architecture, interfacial interactions, and mechanical properties of natural materials, supplies the inspiration for constructing high performance lightweight nanocomposites. Graphene’s high tensile strength, Young’s modulus, and electrical conductivity when compared with other nanomaterials make it an ideal building block for constructing high performance bioinspired nanocomposites. Such nanocomposites demonstrate promise for applications in many fields, including aerospace, aeronautics, submarine devices, car, and flexible electronic devices. In this review, we focus on the bioinspired strategy for preparing graphene-based nanocomposites (GBNs), and discuss the various interfacial interactions. Then the synergistic effects from building blocks and interfacial interactions are discussed in detail, along with the resultant GBNs used in the applications of sensors, actuators, supercapacitors, and nanogenerators, are also illustrated. These GBNs include, for example, one-dimensional (1D) fiber, two-dimensional (2D) film, and three-dimensional (3D) bulk nanocomposites. Finally, we provide our perspective on GBNs, and discuss how to efficiently mimic natural materials for creating new multifunctional bioinspired nanocomposites for practical applications in the near future.
    | PDF
67. Super-tough artificial nacre based on graphene oxide via synergistic interface interactions of π-π stacking and hydrogen bonding
    Pingan Song*, Zhiguang Xu, Yuanpeng Wu, Qunfeng Cheng*, Qipeng Guo*, and Hao Wang
    Carbon, 2017, 111, 807-812. DOI: 10.1016/j.carbon.2016.10.067
    Abstract
    Inspired by interfacial interactions of protein matrix and the crystal platelets in nacre, herein, a super-tough artificial nacre was produced through constructing the synergistic interface interactions of π-π interaction and hydrogen bonding between graphene oxide (GO) nanosheets and sulfonated styrene-ethylene/butylene-styrene copolymer synthesized with multifunctional benzene. The resultant GO-based artificial nacre showed super-high toughness of 15.3 ± 2.5 MJ/m3, superior to natural nacre and other GO-based nanocomposites. The ultra-tough property of the novel nacre was attributed to synergistic effect of π-π stacking interactions and hydrogen bonding. This bioinspired synergistic toughening strategy opens a new avenue for constructing high performance GO-based nanocomposites in the near future.
    | PDF

2016

42. Bioinspired robust nanocomposites of cooper ions and hydroxypropyl cellulose synergistic toughening graphene oxide
    Qi Zhang, Sijie Wan, Lei Jiang, and Qunfeng Cheng*
    Sci. China Technol. Sci., 2016, 60, 758-764. DOI: 10.1007/s11431-016-0529-3
    Abstract
    The hierarchical micro/nanoscale layered formation of organic and inorganic components of natural nacre, results in abundant interfacial interactions, providing an inspiration for fabricating bioinspired nanocomposites through constructing the interfacial interactions. Herein, we demonstrated the synergistic interfacial interactions of hydrogen bonding from hydroxypropyl cellulose and ionic bonding from copper ions upon the reduced graphene oxide based bioinspired nanocomposites, which show the integrated tensile strength, toughness and excellent fatigue-resistant property, as well as high electrical conductivity. These extraordinary properties allow this kind of bioinspired nanocomposites to potentially utilize in the fields of aerospace, flexible electronics devices, etc. This study also opens a door for fabricating excellent mechanical performance graphene-based bioinspired nanocomposites via synergistic interfacial interactions in the future.
    | PDF
43. Robust bioinspired graphene-based nanocomposites via synergistic toughening of zinc ions and covalent bonding
    Shanshan Gong, Lei Jiang, and Qunfeng Cheng*
    J. Mater. Chem. A, 2016, 4, 17073-17079. DOI: 10.1039/C6TA06893F
    Abstract
    Robust graphene-based nanocomposites show promising applications in fields of flexible, wearable and intelligent devices. But, it is still a big challenge to construct high performance macroscopic graphene-based nanocomposites for practical application through cost-efficient graphene oxide (GO) nanosheets. Inspired by the hierarchical layered structure and interfacial interactions of nacre, we demonstrated robust graphene-based nanocomposites via synergistic interfacial interactions, which are constructed via divalent ions of zinc (Zn²⁺⁾, and linear molecules of 10,12-pentacosadiyn-1-ol (PCDO) with GO nanosheets. The synergistic interfacial interactions result in integrated high strength, toughness and fatigue life. Furthermore, the resultant bioinspired graphene-based nanocomposites (BGBNs) also possess high electrical conductivity. The extraordinary performance allows this kind of BGBN to be potentially utilized in aerospace, flexible electrodes of supercapacitors and other intelligent devices. The demonstration of synergistic interfacial interactions of ionic and covalent bonding also supplies an effective approach for building robust graphene-based nanocomposites in the future.
    | PDF | Supplementary Information
44. Science behind nacre: matrix-directed mineralization at ambient condition
    Qunfeng Cheng, and Lei Jiang*
    SCIENCE CHINA Materials, 2016, 59, 889-891. DOI: 10.1007/s40843-016-5116-3
    PDF
45. Low-Cost Coir Fiber Composite with Integrated Strength and Toughness
    
    Fengyun Guo, Nü Wang*, Qunfeng Cheng, Lanlan Hou, Jingchong Liu, Yanlei Yu, and Yong Zhao*
    ACS Sustainable Chem. Eng., 2016, 4, 5450-5455. DOI: 10.1021/acssuschemeng.6b00830
    Abstract
    With the growing environmental problems and depletion of petroleum resources, there is an urgent demand for the biorenewable, sustainable, and environmentally friendly composite materials. Here, we report a green coir fiber composite with specific mechanical properties superior to that of other reported natural fiber/polymer composites. After treatment, both strength and toughness of the composite fiber were substantially improved (91.13% and 175.7% higher than that of untreated counterpart), where exposed cellulose nanofibrils and stacking layer formed by NaOH infusion and the hydroxyl-containing hydrophilic poly(vinyl alcohol) coating play a crucial role in physicochemical interaction and thereby mechanical enhancement. By observing the process of the micro/nanostructure evolution, the strengthened mechanism from nanoscale to macroscale was demonstrated. We believe that this strategy could open new insights into the design of strong and sustainable composite fiber for further practical applications, such as textile, home furnishings, and industrial products.
    | PDF | Supplementary Information
46. Bioinspired Graphene-Based Nanocomposites and Their Application in Flexible Energy Devices
    Sijie Wan, Jingsong Peng, Lei Jiang, and Qunfeng Cheng*
    Adv. Mater., 2016, 8, 7862-7898. DOI: 10.1002/adma.201601934
    Abstract
    Graphene is the strongest and stiffest material ever identified and the best electrical conductor known to date, making it an ideal candidate for constructing nanocomposites used in flexible energy devices. However, it remains a great challenge to assemble graphene nanosheets into macro-sized high-performance nanocomposites in practical applications of flexible energy devices using traditional approaches. Nacre, the gold standard for biomimicry, provides an excellent example and guideline for assembling two-dimensional nanosheets into high-performance nanocomposites. This review summarizes recent research on the bioinspired graphene-based nanocomposites (BGBNs), and discusses different bioinspired assembly strategies for constructing integrated high-strength and -toughness graphene-based nanocomposites through various synergistic effects. Fundamental properties of graphene-based nanocomposites, such as strength, toughness, and electrical conductivities, are highlighted. Applications of the BGBNs in flexible energy devices, as well as potential challenges, are addressed. Inspired from the past work done by the community a roadmap for the future of the BGBNs in flexible energy device applications is depicted.
    | PDF
47. Integrated Ternary Artificial Nacre via Syenrgistic Toughening of Reduced Graphene Oxide/Double-Walled Carbon Nanotubes/Poly(vinyl alcohol)
    Shanshan Gong, Mengxi Wu, Lei Jiang, and Qunfeng Cheng*
    Mater. Res. Express, 2016, 3, 075002. DOI: 10.1088/2053-1591/3/7/075002
    Abstract
    The synergistic toughening effect of building blocks and interface interaction exists in natural materials, such as nacre. Herein, inspired by one-dimensional (1D) nanofibrillar chitin and two-dimensional (2D) calcium carbonate platelets of natural nacre, we have fabricated integrated strong and tough ternary bio-inspired nanocomposites (artificial nacre) successfully via the synergistic effect of 2D reduced graphene oxide (rGO) nanosheets and 1D double-walled carbon nanotubes (DWNTs) and hydrogen bonding cross-linking with polyvinyl alcohol (PVA) matrix. Moreover, the crack mechanics model with crack deflection by 2D rGO nanosheets and crack bridging by 1D DWNTs and PVA chains induces resultant artificial nacre exhibiting excellent fatigue-resistance performance. These outstanding characteristics enable the ternary bioinspired nanocomposites have many promising potential applications, for instance, aerospace, flexible electronics devices and so forth. This synergistic toughening strategy also provides an effective way to assemble robust graphene-based nanocomposites.
    | PDF
48. Bioinspired Ternary Artificial Nacre Nanocomposites Based on Reduced Graphene Oxide and Nanofibrillar Cellulose
    
    Jianli Duan, Shanshan Gong, Yuan Gao, Xiaolin Xie, and Lei Jiang, and Qunfeng Cheng*
    ACS Appl. Mater. Interfaces, 2016, 8, 10545-10550. DOI: 10.1021/acsami.6b02156
    Abstract
    Inspired by the nacre, we demonstrated the integrated ternary artificial nacre nanocomposites through synergistic toughening of graphene oxide (GO) and nanofibrillar cellulose (NFC). In addition, the covalent bonding was introduced between adjacent GO nanosheets. The synergistic toughening effects from building blocks of one-dimensional NFC and two-dimensional GO, interface interactions of hydrogen and covalent bonding together result in the integrated mechanical properties including high tensile strength, toughness, and fatigue life as well as high electrical conductivity. These extraordinary properties of the ternary synthetic nacre nanocomposites allow the support for advances in diverse strategic fields including stretchable electronics, transportation, and energy. Such bioinspired strategy also provides a new insight in designing novel multifunctional nanocomposites.
    | PDF | Supplementary Information
49. Graphene-based artificial nacre nanocompositesYuanyuan Zhang, Shanshan Gong, Qi Zhang, Peng Ming, Sijie Wan, Jingsong Peng, Lei Jiang, and Qunfeng Cheng*
    Chem. Soc. Rev., 2016, 45, 2378-2395. DOI: 10.1039/C5CS00258C
    Abstract
    With its extraordinary properties as the strongest and stiffest material ever measured and the best-known electrical conductor, graphene could have promising applications in many fields, especially in the area of nanocomposites. However, processing graphene-based nanocomposites is very difficult. So far, graphene-based nanocomposites exhibit rather poor properties. Nacre, the gold standard for biomimicry, provides an excellent example and guidelines for assembling two-dimensional nanosheets into high performance nanocomposites. The inspiration from nacre overcomes the bottleneck of traditional approaches for constructing nanocomposites, such as poor dispersion, low loading, and weak interface interactions. This tutorial review summarizes recent research on graphene-based artificial nacre nanocomposites and focuses on the design of interface interactions and synergistic effects for constructing high performance nanocomposites. This tutorial review also focuses on a perspective of the dynamic area of graphene-based nanocomposites, commenting on whether the concept is viable and practical, on what has been achieved to date, and most importantly, what is likely to be achieved in the future.
    | PDF
50. Nacre-inspired Integrated Strong and Tough Reduced Graphene Oxide-Poly(acrylic acid) Nanocomposites
    Qunfeng Cheng*, Sijie Wan, Han Hu, Jingsong Peng, Yuchen Li, Yuzun Fan, and Lei Jiang
    Nanoscale, 2016, Advance Article. DOI: 10.1039/C6NR00562D
    Abstract
    Inspired by the relationship of interface interactions with high performance mechanical properties of nacre, an integrated strong and tough nacre-inspired nanocomposite was demonstrated based on graphene oxide (GO) polyacrylic acid (PAA) via vacuum-assisted filtration self-assembly process. The abundant hydrogen bonding between GO and PAA results in the integrated high strength and toughness of the artificial nacre, which is 2 and 3.3 times higher than that of pure reduced GO film. Moreover, this nacre-inspired nanocomposite also displays high electrical conductivity of 108.9 S/cm. All these fantastic physical properties allow this kind of nacre-inspired nanocomposite to be used in many applications, such as flexible electrode, aerospace, and artificial muscles et al. This nacre-inspired strategy also opens an avenue for constructing the integrated high performance graphene-based nanocomposites in the near future.
    | PDF | Supplementary Information
51. Ultrastrong Bioinspired Graphene-Based Fibers via Synergistic Toughening
    Yuanyuan Zhang, Yuchen Li, Peng Ming, Qi Zhang, Tianxi Liu, Lei Jiang, and Qunfeng Cheng*
    Adv. Mater., 2016, 28, 2834-2839. DOI: 10.1002/adma.201506074
    Abstract
    Ultrastrong bioinspired graphene-based fibers are designed and prepared via synergistic toughening of ionic and covalent bonding. The tensile strength reaches up to 842.6 MPa and is superior to all other reported graphene-based fibers. In addition, its electrical conductivity is as high as 292.4 S cm⁻¹. This bioinspired synergistic toughening strategy supplies new insight toward the construction of integrated high-performance graphene-based fibers in the near future.
    | PDF | Supplementary Information | Nature研究亮点报道： Shells spark strong graphene fibre (PDF)

2015

32. Use of Synergistic Interactions to Fabricate Strong, Tough, and Conductive Artificial Nacre Based on Graphene Oxide and Chitosan
    Sijie Wan, Jingsong Peng, Yuchen Li, Han Hu, Lei Jiang, and Qunfeng Cheng*
    ACS Nano, 2015, 9, 9830-9836. DOI: 10.1021/acsnano.5b02902
    Abstract
    Graphene is the strongest and stiffest material, leading to the development of promising applications in many fields. However, the assembly of graphene nanosheets into macrosized nanocomposites for practical applications remains a challenge. Nacre in its natural form sets the “gold standard” for toughness and strength, which serves as a guide to the assembly of graphene nanosheets into high-performance nanocomposites. Here we show the strong, tough, conductive artificial nacre based on graphene oxide through synergistic interactions of hydrogen and covalent bonding. Tensile strength and toughness was 4 and 10 times higher, respectively, than that of natural nacre. The exceptional integrated strong and tough artificial nacre has promising applications in aerospace, artificial muscle, and tissue engineering, especially for flexible supercapacitor electrodes due to its high electrical conductivity. The use of synergistic interactions is a strategy for the development of high-performance nanocomposites.
    | PDF | Supplementary Information
33. Synergistic Toughening of Graphene Oxide–Molybdenum Disulfide–Thermoplastic Polyurethane Ternary Artificial Nacre
    Sijie Wan, Yuchen Li, JingsongPeng, Han Hu, Qunfeng Cheng*, and Lei Jiang
    ACS Nano, 2015, 9, 708-714. DOI: 10.1021/nn506148w
    Abstract
    Inspired by the ternary structure of natural nacre, robust ternary artificial nacre is constructed through synergistic toughening of graphene oxide (GO) and molybdenum disulfide (MoS₂) nanosheets via a vacuum-assisted filtration self-assembly process. The synergistic toughening effect from high mechanical properties of GO and lubrication of MoS₂ nanosheets is successfully demonstrated. Meanwhile, the artificial nacre shows high electrical conductivity. This approach for constructing robust artificial nacre by synergistic effect from GO and MoS₂ provides a creative opportunity for designing and fabricating integrated artificial nacre in the near future, and this kind of ternary artificial nacre has great potential applications in aerospace, flexible supercapacitor electrodes, artificial muscle, and tissue engineering.
    | PDF | Supplementary Information
34. Integrated Ternary Bioinspired Nanocomposites via Synergistic Toughening of Reduced Graphene Oxide and Double-Walled Carbon Nanotubes
    Shanshan Gong, Wei Cui, Qi Zhang, Anyuan Cao, Lei Jiang, and Qunfeng Cheng*
    ACS Nano, 2015, 9, 11568-11573. DOI: 10.1021/acsnano.5b05252
    Abstract
    With its synergistic toughening effect and hierarchical micro/nanoscale structure, natural nacre sets a “gold standard” for nacre-inspired materials with integrated high strength and toughness. We demonstrated strong and tough ternary bioinspired nanocomposites through synergistic toughening of reduced graphene oxide and double-walled carbon nanotube (DWNT) and covalent bonding. The tensile strength and toughness of this kind of ternary bioinspired nanocomposites reaches 374.1 ± 22.8 MPa and 9.2 ± 0.8 MJ/m³, which is 2.6 and 3.3 times that of pure reduced graphene oxide film, respectively. Furthermore, this ternary bioinspired nanocomposite has a high conductivity of 394.0 ± 6.8 S/cm and also shows excellent fatigue-resistant properties, which may enable this material to be used in aerospace, flexible energy devices, and artificial muscle. The synergistic building blocks with covalent bonding for constructing ternary bioinspired nanocomposites can serve as the basis of a strategy for the construction of integrated, high-performance, reduced graphene oxide (rGO)-based nanocomposites in the future.
    | PDF | Supplementary Information
35. Learning from Nature: Constructing Integrated Graphene-Based Artificial Nacre
    Qunfeng Cheng*, Jianli Duan, Qi Zhang, and Lei Jiang
    ACS Nano, 2015, 9, 2231-2234. DOI: 10.1021/acsnano.5b01126
    Abstract
    Natural nacre supplies a number of properties that can be used in designing high-performance bioinspired materials. Likewise, due to the extraordinary properties of graphene, a series of bioinspired graphene-based materials have recently been demonstrated. Compared to other approaches for constructing graphene-based materials, bioinspired concepts result in high-loading graphene, and the resultant high-performance graphene-based artificial nacres demonstrate isotropic mechanical and electrical properties. In this Perspective, we describe how to construct integrated graphene-based artificial nacre through the synergistic relationship between interface interactions and building blocks. These integrated graphene-based artificial nacres show promising applications in many fields, such as aerospace, flexible supercapacitor electrodes, artificial muscle, and tissue engineering.
    | PDF
36. Nacre-inspired integrated nanocomposites with fire retardant properties by graphene oxide and montmorillonite
    Peng Ming, Zhaofei Song, Shanshan Gong, Yuanyuan Zhang, JianliDuan, Qi Zhang, Lei Jiang, and Qunfeng Cheng*
    J. Mater. Chem. A, 2015, 3, 21194-21200. DOI: 10.1039/C5TA05742F
    Abstract
    Natural nacre exhibits extraordinary strong and tough properties with its brick-and-mortar structure that was perfected after millions of years of evolution. Inspired by nacre’s hierarchical structure, we fabricated multifunctional bioinspired nanocomposites of graphene oxide (GO) and montmorillonite (MMT) nanosheets with poly(vinyl alcohol) (PVA) via a vacuum-assisted filtration self-assembly process. By combining graphene oxide and montmorillonite with PVA, we demonstrated an effective synergistic toughening effect and obtained integrated strong and tough bioinspired nanocomposites. Furthermore, these nanocomposites show high fatigue-resistant properties, high electrical conductivity and good fire retardant properties. As such, they have promising potential in many applications, including flexible electrodes, flame retardant insulation and as aerospace materials. The technique developed here provides new insights for designing nanocomposites with a complex hierarchical structure that mimic nacre.
    | PDF | Supplementary Information
37. Bioinspired highly electrically conductive graphene–epoxy layered composites
    Peng Ming,Yuanyuan Zhang, Jianwen Bao, Gang Liu, Zhou Li, Lei Jiang, and Qunfeng Cheng*
    RSC Adv., 2015, 5, 22283-22288. DOI: 10.1039/C5RA00233H
    Abstract
    Inspired by the nano/micro-scale hierarchical structure of nacre, we developed a new method for fabricating highly electrically conductive graphene–epoxy layered composites. In this new method, the graphene loading can be easily controlled, and the intrinsic three-dimensional network of graphene in the composites results in high electrical conductivity. Through effective surface modification, the interface strength between graphene and epoxy matrix was dramatically improved, leading to the 23-fold improvement in tensile strength, 136-fold in Young’s modulus, and 8-fold in electrical conductivity compared with the pure graphene foam. These high performance bioinspired graphene–epoxy layered composites have a great potential for applications in electromagnetic interference (EMI) shielding, aerospace, and other electrical devices.
    | PDF | Supplementary Information

2014

26. Bioinspired Green Composite Lotus Fibers
    Mengxi Wu, Hua Shuai, Qunfeng Cheng*, and Lei Jiang
    Angew. Chem. Int. Ed., 2014, 53, 3358-3361. DOI: 10.1002/anie.201310656
    Abstract
    Owing to the growing global environmental problems, demands for environmentally friendly, fully biodegradable sustainable composites have substantially increased across various industries. Inspired by the composite structure of cocoon silk, we fabricated a fully green composite fiber (GCF) that is based on the lotus fiber (LF) and a biodegradable polymer, namely poly(vinyl alcohol) (PVA). After the formation of cross-linkages between the LF and PVA, the mechanical properties of this bioinspired GCF had substantially improved. In particular, the specific mechanical properties are superior to those of cocoon silk and other natural fibers. These findings suggest that LFs may be used as reinforcement materials for the fabrication of bulk green materials for various industries, such as the textile, medical, automobile, and aerospace industries.
    | PDF | Supplementary Information
27. Synergistic Toughening of BioinspiredPoly(vinyl alcohol)–Clay–Nanofibrillar Cellulose Artificial Nacre
    Jianfeng Wang, Qunfeng Cheng*, Ling Lin, and Lei Jiang
    ACS Nano, 2014, 8, 2739-2745. DOI: 10.1021/nn406428n
    Abstract
    Inspired by the layered aragonite platelet/nanofibrillar chitin/protein ternary structure and integration of extraordinary strength and toughness of natural nacre, artificial nacre based on clay platelet/nanofibrillar cellulose/poly(vinyl alcohol) is constructed through an evaporation-induced self-assembly technique. The synergistic toughening effect from clay platelets and nanofibrillar cellulose is successfully demonstrated. The artificial nacre achieves an excellent balance of strength and toughness and a fatigue-resistant property, superior to natural nacre and other conventional layered clay/polymer binary composites.
    | PDF | Supplementary Information
28. A Strong Integrated Strength and Toughness Artificial Nacre Based on Dopamine Cross-Linked Graphene Oxide
    Wei Cui, Mingzhu Li, Jiyang Liu, Ben Wang, Chuck Zhang, Lei Jiang, and Qunfeng Cheng*
    ACS Nano, 2014, 8, 9511-9517. DOI: 10.1021/nn503755c
    Abstract
    Demands of the strong integrated materials have substantially increased across various industries. Inspired by the relationship of excellent integration of mechanical properties and hierarchical nano/microscale structure of the natural nacre, we have developed a strategy for fabricating the strong integrated artificial nacre based on graphene oxide (GO) sheets by dopamine cross-linking via evaporation-induced assembly process. The tensile strength and toughness simultaneously show 1.5 and 2 times higher than that of natural nacre. Meanwhile, the artificial nacre shows high electrical conductivity. This type of strong integrated artificial nacre has great potential applications in aerospace, flexible supercapacitor electrodes, artificial muscle, and tissue engineering.
    | PDF | Supplementary Information
29. Bioinspired Layered Materials with Superior Mechanical Performance
    Qunfeng Cheng*, Lei Jiang, and Zhiyong Tang*
    Acc. Chem. Res., 2014, 47, 1256-1266. DOI: 10.1021/ar400279t
    Conspectus
    Nature has inspired researchers to construct structures with ordered layers as candidates for new materials with high mechanical performance. As a prominent example, nacre, also known as mother of pearl, consists of a combination of inorganic plates (aragonite calcium carbonate, 95% by volume) and organic macromolecules (elastic biopolymer, 5% by volume) and shows a unique combination of strength and toughness. Investigations of its structure reveal that the hexagonal platelets of calcium carbonate and the amorphous biopolymer are alternatively assembled into the orderly layered structure. The delicate interface between the calcium carbonate and the biopolymer is well defined. Both the building blocks that make up these assembled layers and the interfaces between the inorganic and organic components contribute to the excellent mechanical property of natural nacre.In this Account, we summarize recent research from our group and from others on the design of bioinspired materials composed by layering various primitive materials. We focus particular attention on nanoscale carbon materials. Using several examples, we describe how the use of different combinations of layered materials leads to particular properties. Flattened double-walled carbon nanotubes (FDWCNTs) covalently cross-linked in a thermoset three-dimensional (3D) network produced the materials with the highest strength. The stiffest layered materials were generated from borate orthoester covalent bonding between adjacent graphene oxide (GO) nanosheets, and the toughest layered materials were fabricated with Al2O3 platelets and chitosan via hydrogen bonding. These new building blocks, such as FDWCNTs and GO, and the replication of the elaborate micro-/nanoscale interface of natural nacre have provided many options for developing new high performance artificial materials.The interface designs for bioinspired layered materials are generally categorized into (1) hydrogen bonding, (2) ionic bonding, and (3) covalent bonding. Using these different strategies, we can tune the materials to have specific mechanical characteristics such as high strength, excellent strain resistance, or remarkable toughness. Among these design strategies, hydrogen bonding affords soft interfaces between the inorganic plates and the organic matrix. Covalent cross-linking forms chemical bonds between the inorganic plates and the organic matrix, leading to much stronger interfaces. The interfaces formed by ionic bonding are stronger than those formed by hydrogen bonding but weaker than those formed by covalent bonding.
    | PDF

2013

22. Ultratough Artificial Nacre Based on Conjugated Cross-linked Graphene Oxide
    Qunfeng Cheng*, Mengxi Wu, Mingzhu Li*, Lei Jiang, and Zhiyong Tang*
    Angew. Chem., Int. Ed., 2013, 52, 3750-3755. DOI: 10.1002/anie.201210166
    Abstract
    Inspired by natural nacre, layered composites based on graphene oxide (GO) and 10,12-pentacosadiyn-1-ol (PCDO) have been successfully fabricated. PCDO molecules are grafted onto GO sheets and cross-linked with each other, resulting in a superior toughness that is two times higher than that of the natural nacre.
    | PDF | Supplementary Information
23. Understanding the relationship of performance with nanofiller content in the biomimetic layered nanocomposites
    Jianfeng Wang, Qunfeng Cheng*, Ling Lin, Linfeng Chen, and Lei Jiang
    Nanoscale, 2013, 5, 6356-6362. DOI: 10.1039/C3NR00801K
    Abstract
    Montmorillonite/poly(vinyl alcohol) (MMT/PVA) nanocomposites spanning the complete range of MMT content (0–100 wt%) are prepared by simple evaporation-induced assembly. Effects of MMT content on the structure and mechanical properties of nanocomposites are systematically investigated and exhibit two important transitions at MMT contents of 30 wt% and 70 wt%. In the range of 0–30 wt%, the nanocomposites show a random structure. With the content of PVA increasing, the mechanical properties of the resultant nanocomposites were dramatically enhanced and were higher than that by prediction according to the conventional composite model. In the range of 30–70 wt%, the nanocomposites show a nacre-like layered structure with alternating MMT platelets and PVA layers, and all PVA is completely restricted by MMT platelets. The mechanical properties of nanocomposites were further improved by increasing the content of MMT, and reached the maximum value at the MMT content of 70 wt%. The 70 wt% MMT/PVA nanocomposite has a tensile strength of 219 ± 19 MPa, which is 5.5 times higher than that of a pure PVA film and surpasses nacre and reported biomimetic layered clay/PVA composites. When the MMT content is higher than 70 wt%, the layered structure is transformed to tactoids, which deteriorate mechanical properties. These results offer comprehensive understanding for developing high-performance biomimetic layered nanocomposite materials with high nanofiller loading.
    | PDF | Supplementary Information

2012

20. Bioinspired Layered Composites Based on Flattened Double-Walled Carbon Nanotubes
    Qunfeng Cheng*, Mingzhu Li, Lei Jiang, and Zhiyong Tang*
    Adv. Mater., 2012, 24, 1838-1843. DOI: 10.1002/adma.201200179
    Abstract
    Inspired by the layered hierarchical nano- and microstructures of natural nacre, flattened double-walled carbon nanotube (FDWCNT) reinforced epoxy composites are fabricated. Impressively, the prepared composites exhibit layered structures analogous to nacre, and the FDWCNT loading can reach 70 wt%, which results in superior mechanical properties that evidently outperform other existing materials.
    | PDF | Supplementary Information
21. A Strong Bio-Inspired Layered PNIPAM–Clay Nanocomposite Hydrogel
    Jianfeng Wang,Ling Lin, Qunfeng Cheng*, and Lei Jiang
    Angew. Chem. Int. Ed., 2012, 51, 4676-4680. DOI: 10.1002/anie.201200267
    Abstract
    Inspired by nacre, a layered poly(N-isopropylacrylamide)–clay nanocomposite hydrogel was successfully fabricated by combination of vacuum-filtration self-assembly and photo-initiated in situ polymerization. This bio-inspired layered nanocomposite hydrogel shows excellent mechanical properties, which can rival some biological soft tissues (see picture).
    | PDF | Supplementary Information
22. Layered nanocomposites inspired by the structure and mechanical properties of nacre
    Jianfeng Wang, Qunfeng Cheng*, and Zhiyong Tang*
    Chem. Soc. Rev., 2012, 41, 1111-1129. DOI: 10.1039/C1CS15106A
    Abstract
    Nacre (mother-of-pearl), made of inorganic and organic constituents (95 vol% aragonite calcium carbonate (CaCO₃) platelets and 5 vol% elastic biopolymers), possesses a unique combination of remarkable strength and toughness, which is compatible for conventional high performance materials. The excellent mechanical properties are related to its hierarchical structure and precisely designed organic–inorganic interface. The rational design of aragonite platelet strength, aspect ratio of aragonite platelets, and interface strength ensures that the strength of nacre is maximized under platelet pull-out failure mode. At the same time, the synergy of strain hardening mechanisms acting over multiple scales results in platelets sliding on one another, and thus maximizes the energy dissipation of viscoplastic biopolymers. The excellent integrated mechanical properties with hierarchical structure have inspired chemists and materials scientists to develop biomimetic strategies for artificial nacre materials. This critical review presents a broad overview of the state-of-the-art work on the preparation of layered organic–inorganic nanocomposites inspired by nacre, in particular, the advantages and disadvantages of various biomimetic strategies. Discussion is focused on the effect of the layered structure, interface, and component loading on strength and toughness of nacre-mimic layered nanocomposites (148 references).
    | PDF
23. An underwater pH-responsive superoleophobic surface with reversibly switchable oil-adhesion
    Qunfeng Cheng, Mingzhu Li, Fu Yang, Mingjie Liu,Lin Li, Shutao Wang*, and Lei Jiang
    Soft Matter, 2012, 8, 6740-6743. DOI: 10.1039/C2SM25421B
    Abstract
    An underwater pH-responsive superoleophobic surface successfully demonstrated a reversible switch of oil-adhesion on a nanostructured poly(acrylic acid) (PAA) surface by changing the environmental pH values. At low pH, intramolecular hydrogen bonding of PAA is formed, and results in high oil-adhesion. As for high pH, the oil droplets can easily roll off due to the intermolecular hydrogen bonding between PAA and surrounding water.
    | PDF | Supplementary Information