Synthesis and applications of three-dimensional(3 D)porous graphene frameworks(GFs)have attracted extensive interest owing to their intriguing advantages of high specific surface area,enriched porosity,excellent elect...Synthesis and applications of three-dimensional(3 D)porous graphene frameworks(GFs)have attracted extensive interest owing to their intriguing advantages of high specific surface area,enriched porosity,excellent electrical conductivity,exceptional compressibility and processability.However,it is still challenging for economically viable,fast and scalable assembly of 3 D GFs at room-temperature.Herein,we reported a one-step scalable strategy for fast self-assembly of graphene oxide into 3 D macroscopically porous GFs,with assistance of polyoxometalates(POM)as functional cross-linker and hydrazine hydrate as reductant at room-temperature.The resulting 3 D interconnected macroporous POM-GFs uniformly decorated with ultrasmall POM nanoclusters were directly processed into binder-/additive-free film compact electrodes(1.68 g cm^(-3))with highly aligned,layer-stacked structure and electrically conductivity(622 S m-1)for high-performance supercapacitors,showing an impressive gravimetric capacitance of205 F g-1,volumetric capacitance of 334 F cm^(-3) at 1 mV s^(-1),and remarkable cycling stability with capacitance retention of 83%after 10,000 cycles,outperforming the most reported GFs.Further,the solid-state supercapacitors offered excellent gravimetric capacitance of 157 F g-1 exceptionally volumetric capacitance of 115 F cm^(-3) at 2 mV s^(-1) based on single electrode,and volumetric energy density of2.6 mWh cm^(-3).Therefore,this work will open novel opportunities to room-temperature fast assembly of 3 D porous graphene architectures for high-energy-density supercapacitors.展开更多
With the rapid growth in electronic device performance,there has been an increasing demand for thermally conductive polymer composites to handle the thermal management issue,thus contributing to the great importance t...With the rapid growth in electronic device performance,there has been an increasing demand for thermally conductive polymer composites to handle the thermal management issue,thus contributing to the great importance to develop the graphene framework,which is evaluated as the most promising reinforcements for enhancing the thermal conductivity of polymer.Vacuum filtration is a common method to fabricate graphene framework,whereas,it is available to prepare a framework with centimeter-scale thickness by filtrating the graphene-water dispersion,due to the fact of sample cracking caused by the mismatch of surface tension between graphene and water.In this work,a surfactantassisted strategy was proposed by adjusting the surface tension of the water close to that of graphene first,then performing a conventional filtration process,to fabricate graphene framework.As a result,a thick graphene framework(thickness:3 cm)was successfully prepared,and after embedding into epoxy,the framework endows the composite(13.6 wt%)with a high in-plane thermal conductivities of12.4 W/mK,which is equivalent to≈64 times higher than that of neat epoxy.Our method is simple and compatible with the conventional filtration process,suggesting great potential for the mass-production of graphene framework to meet the practical application requirements.展开更多
A free-standing paper-like three-dimensional graphene framework（3DGF） with orientated laminar structure and interconnected macropores, was obtained by the hard template-directed ordered assembly. As the sacrificial ...A free-standing paper-like three-dimensional graphene framework（3DGF） with orientated laminar structure and interconnected macropores, was obtained by the hard template-directed ordered assembly. As the sacrificial templates, polystyrene（PS） latex spheres were assembled with graphene oxide（GO） to build up a sandwich type composite film, followed by heat removal of which with a simultaneous reduction of GO. The 3DGF exhibited high specific surface area of 402.5 m2/g, controllable pores and mechanical flexibility, which was employed as the binder-free supercapacitor electrode and shows high specific gravimetric capacitance of 95 F/g at 0.5 A/g, with enhanced rate capability in 3 electrode KOH system.展开更多
Metal sulfides as a feasible candidate with high specific capacitance for supercapacitors suffer from sluggish ion/electron transport kinetics and rapid capacitance fading. Herein, we demonstrate a method to fabricate...Metal sulfides as a feasible candidate with high specific capacitance for supercapacitors suffer from sluggish ion/electron transport kinetics and rapid capacitance fading. Herein, we demonstrate a method to fabricate a composite of reduced graphene oxide（rGO） with hollow Co9S8 derived from metal organic framework（MOF）. Due to the combined highly conductive rGO substrates and hollow shell, the prepared r GO/Co9S8 composite exhibits a high specific capacitance of 575.9 F/g at 2 A/g and 92.0% capacitance retention after 9000 cycles. Its excellent electrochemical performance provides great promise for application, and this versatile method can be extended to prepare other similar nanocomposite.展开更多
Two-dimensional(2D)heterostructures hold great promise in designing integrated materials,while the current synthesis strategies still confront challenges for multilayer heterostructure construction and scale-up produc...Two-dimensional(2D)heterostructures hold great promise in designing integrated materials,while the current synthesis strategies still confront challenges for multilayer heterostructure construction and scale-up production.Here we report a generalized host-vip strategy based on nonexfoliated layered graphene oxide(LGO)to construct graphene-based heterostructures that consist of multilayered,alternately aligned graphene and metal oxide nanosheets.The 2D-aligned GOs and open interlayer spaces make LGO an ideal platform to create periodic 2D host frameworks.Polyetheramine oligomers covalently bond the adjacent GOs.The extended chain conformation endows the resulting accordionlike GO frameworks with high structural stability,periodicity and enlarged interlayer space.Owing to the high affinity of the open and well-arranged 2D channels toward vip precursors,a variety of high-quality heterostructures can be synthesized.Furthermore,a variety of exfoliated,ultrathin metal oxide nanosheets can also be prepared by removing the graphene skeleton.The flexible interlayer chemistry presented in this study paves a way toward the synthesis of a large family of graphene-inorganic/organic 2D heterostructures.展开更多
Lithium-air batteries have attracted significant interest for applications in high energy density mobile power supplies, yet there are considerable challenges to the development of rechargeable Li-air batteries with s...Lithium-air batteries have attracted significant interest for applications in high energy density mobile power supplies, yet there are considerable challenges to the development of rechargeable Li-air batteries with stable cycling performance under ambient conditions. Here we report a three-dimensional （3D） hydrophobic graphene membrane as a moisture-resistive cathode for high performance Li-air batteries. The 3D graphene membrane features a highly interconnected graphene network for efficient charge transport, a highly porous structure for efficient diffusion of oxygen and electrolyte ions, a large specific surface area for high capacity storage of the insulating discharge product, and a network of highly tortuous hydrophobic channels for O2/H20 selectivity. These channels facilitate 02 ingression while retarding moisture diffusion and ensure excellent charge/ discharge cycling stability under ambient conditions. The membrane can thus enable robust Li-air batteries with exceptional performance, including a maximum cathode capacity that exceeds 5,700 mAh/g and excellent recharge cycling behavior （〉2,000 cycles at 140 mAh/g, and 〉100 cycles at 1,400 mAh/g）. The graphene membrane air cathode can deliver a lifetime capacity of 100,000-300,000 mAh/g, comparable to that of a typical lithium ion battery cathode. The stable operation of Li-air batteries with significantly improved single charge capacities and lifetime capacities comparable to those of Li-ion batteries may offer an attractive high energy density storage alternative for future mobile power supplies. These batteries may provide much longer battery lives and greatly reduced recharge frequency.展开更多
Mesoporous carbons have been widely utilized as the sulfur host for lithium-sulfur(Li-S)batteries.The ability to engineer the porosity,wall thickness,and graphitization degree of the carbon host is essential for addre...Mesoporous carbons have been widely utilized as the sulfur host for lithium-sulfur(Li-S)batteries.The ability to engineer the porosity,wall thickness,and graphitization degree of the carbon host is essential for addressing issues that hamper commercialization of Li-S batteries,such as fast capacity decay and poor high-rate performance.In this work,highly ordered,ultrathin mesoporous graphitic-carbon frameworks(MGFs)having unique cage-like mesoporosity,derived from self-assembled Fe_(3)0_(4)nanoparticle superlattices,are demonstrated to be an excellent host for encapsulating sulfur.The resulting S@MGFs exhibit high specific capacity(1,446 mAh.g-1 at 0.15 C),good rate capability(430 mAh.g-1 at 6 C),and exceptional cycling stability(-0.049%capacity decay per cycle at 1 C)when used as Li-S cathodes.The superior electrochemical performance of the S@MGFs is attributed to the many unique and advantageous structural features of MGFs.In addition to the interconnected,ultrathin graphitic-carbon framework that ensures rapid electron and lithium-ion transport,the microporous openings between adjacent mesopores efficiently suppress the diffusion of polysulfides,leading to improved capacity retention even at high current densities.展开更多
基金financially supported by the National Key R@D Program of China(Grants 2016YFB0100100,2016YFA0200200)the National Natural Science Foundation of China(Grant Nos.51872283,22075279,21805273,22005297,22005298)+7 种基金the Liao Ning Revitalization Talents Program(Grant XLYC1807153)the Natural Science Foundation of Liaoning ProvinceJoint Research Fund Liaoning-Shenyang National Laboratory for Materials Science(Grant 20180510038)Dalian Innovation Support Plan for High Level Talents(2019RT09)the Dalian National Laboratory For Clean Energy(DNL),CASDNL Cooperation Fund,CAS(DNL180310,DNL180308,DNL201912,and DNL201915)DICP(DICP ZZBS201708,DICP ZZBS201802,DICP I2020032)the China Postdoctoral Science Foundation(2019M661141,2020M680995)。
文摘Synthesis and applications of three-dimensional(3 D)porous graphene frameworks(GFs)have attracted extensive interest owing to their intriguing advantages of high specific surface area,enriched porosity,excellent electrical conductivity,exceptional compressibility and processability.However,it is still challenging for economically viable,fast and scalable assembly of 3 D GFs at room-temperature.Herein,we reported a one-step scalable strategy for fast self-assembly of graphene oxide into 3 D macroscopically porous GFs,with assistance of polyoxometalates(POM)as functional cross-linker and hydrazine hydrate as reductant at room-temperature.The resulting 3 D interconnected macroporous POM-GFs uniformly decorated with ultrasmall POM nanoclusters were directly processed into binder-/additive-free film compact electrodes(1.68 g cm^(-3))with highly aligned,layer-stacked structure and electrically conductivity(622 S m-1)for high-performance supercapacitors,showing an impressive gravimetric capacitance of205 F g-1,volumetric capacitance of 334 F cm^(-3) at 1 mV s^(-1),and remarkable cycling stability with capacitance retention of 83%after 10,000 cycles,outperforming the most reported GFs.Further,the solid-state supercapacitors offered excellent gravimetric capacitance of 157 F g-1 exceptionally volumetric capacitance of 115 F cm^(-3) at 2 mV s^(-1) based on single electrode,and volumetric energy density of2.6 mWh cm^(-3).Therefore,this work will open novel opportunities to room-temperature fast assembly of 3 D porous graphene architectures for high-energy-density supercapacitors.
基金financial support by the National Key R&D Program of China (No.2017YFB0406000)Scientific Instrument Developing Project of the Chinese Academy of Sciences (No.YZ201640)+6 种基金the Project of the Chinese Academy of Sciences (No.KFZD-SW-409)Science and Technology Major Project of Ningbo (Nos.2016S1002 and 2016B10038)International S&T Cooperation Program of Ningbo (No. 2017D10016) for financial supportthe Chinese Academy of Sciences for Hundred Talents ProgramChinese Central Government for Thousand Young Talents Program3315 Program of Ningbothe Key Technology of Nuclear Energy (CAS Interdisciplinary Innovation Team,2014)
文摘With the rapid growth in electronic device performance,there has been an increasing demand for thermally conductive polymer composites to handle the thermal management issue,thus contributing to the great importance to develop the graphene framework,which is evaluated as the most promising reinforcements for enhancing the thermal conductivity of polymer.Vacuum filtration is a common method to fabricate graphene framework,whereas,it is available to prepare a framework with centimeter-scale thickness by filtrating the graphene-water dispersion,due to the fact of sample cracking caused by the mismatch of surface tension between graphene and water.In this work,a surfactantassisted strategy was proposed by adjusting the surface tension of the water close to that of graphene first,then performing a conventional filtration process,to fabricate graphene framework.As a result,a thick graphene framework(thickness:3 cm)was successfully prepared,and after embedding into epoxy,the framework endows the composite(13.6 wt%)with a high in-plane thermal conductivities of12.4 W/mK,which is equivalent to≈64 times higher than that of neat epoxy.Our method is simple and compatible with the conventional filtration process,suggesting great potential for the mass-production of graphene framework to meet the practical application requirements.
基金financial support from the Natural Science Foundation of China(51302281 and 51402324)Natural Science Foundation of Shanxi Province(2013011012–7)
文摘A free-standing paper-like three-dimensional graphene framework（3DGF） with orientated laminar structure and interconnected macropores, was obtained by the hard template-directed ordered assembly. As the sacrificial templates, polystyrene（PS） latex spheres were assembled with graphene oxide（GO） to build up a sandwich type composite film, followed by heat removal of which with a simultaneous reduction of GO. The 3DGF exhibited high specific surface area of 402.5 m2/g, controllable pores and mechanical flexibility, which was employed as the binder-free supercapacitor electrode and shows high specific gravimetric capacitance of 95 F/g at 0.5 A/g, with enhanced rate capability in 3 electrode KOH system.
基金Financial support from National Key Project (No. 2017YFF0210703)Distinguished Young Scientists Program of the National Natural Science Foundation of China (Nos. 51425301, 21374021, 51673096 and U1601214)
文摘Metal sulfides as a feasible candidate with high specific capacitance for supercapacitors suffer from sluggish ion/electron transport kinetics and rapid capacitance fading. Herein, we demonstrate a method to fabricate a composite of reduced graphene oxide（rGO） with hollow Co9S8 derived from metal organic framework（MOF）. Due to the combined highly conductive rGO substrates and hollow shell, the prepared r GO/Co9S8 composite exhibits a high specific capacitance of 575.9 F/g at 2 A/g and 92.0% capacitance retention after 9000 cycles. Its excellent electrochemical performance provides great promise for application, and this versatile method can be extended to prepare other similar nanocomposite.
基金This work was supported by Shanghai International Collaboration Research Project(19520713900).
文摘Two-dimensional(2D)heterostructures hold great promise in designing integrated materials,while the current synthesis strategies still confront challenges for multilayer heterostructure construction and scale-up production.Here we report a generalized host-vip strategy based on nonexfoliated layered graphene oxide(LGO)to construct graphene-based heterostructures that consist of multilayered,alternately aligned graphene and metal oxide nanosheets.The 2D-aligned GOs and open interlayer spaces make LGO an ideal platform to create periodic 2D host frameworks.Polyetheramine oligomers covalently bond the adjacent GOs.The extended chain conformation endows the resulting accordionlike GO frameworks with high structural stability,periodicity and enlarged interlayer space.Owing to the high affinity of the open and well-arranged 2D channels toward vip precursors,a variety of high-quality heterostructures can be synthesized.Furthermore,a variety of exfoliated,ultrathin metal oxide nanosheets can also be prepared by removing the graphene skeleton.The flexible interlayer chemistry presented in this study paves a way toward the synthesis of a large family of graphene-inorganic/organic 2D heterostructures.
文摘Lithium-air batteries have attracted significant interest for applications in high energy density mobile power supplies, yet there are considerable challenges to the development of rechargeable Li-air batteries with stable cycling performance under ambient conditions. Here we report a three-dimensional （3D） hydrophobic graphene membrane as a moisture-resistive cathode for high performance Li-air batteries. The 3D graphene membrane features a highly interconnected graphene network for efficient charge transport, a highly porous structure for efficient diffusion of oxygen and electrolyte ions, a large specific surface area for high capacity storage of the insulating discharge product, and a network of highly tortuous hydrophobic channels for O2/H20 selectivity. These channels facilitate 02 ingression while retarding moisture diffusion and ensure excellent charge/ discharge cycling stability under ambient conditions. The membrane can thus enable robust Li-air batteries with exceptional performance, including a maximum cathode capacity that exceeds 5,700 mAh/g and excellent recharge cycling behavior （〉2,000 cycles at 140 mAh/g, and 〉100 cycles at 1,400 mAh/g）. The graphene membrane air cathode can deliver a lifetime capacity of 100,000-300,000 mAh/g, comparable to that of a typical lithium ion battery cathode. The stable operation of Li-air batteries with significantly improved single charge capacities and lifetime capacities comparable to those of Li-ion batteries may offer an attractive high energy density storage alternative for future mobile power supplies. These batteries may provide much longer battery lives and greatly reduced recharge frequency.
基金A.G.D.acknowledges the financial support from the National Basic Research Program of China(No.2014CB845602)Natural National Science Foundation of China(No.21373052)+2 种基金Shanghai International Science and Technology Cooperation Project(No.15520720100)D.Y.is grateful for financial support from Natural National Science Foundation of China(Nos.51373035,51373040,51573030,and 51573028)International Science and Technology Cooperation Program of China(No.2014DFE40130).
文摘Mesoporous carbons have been widely utilized as the sulfur host for lithium-sulfur(Li-S)batteries.The ability to engineer the porosity,wall thickness,and graphitization degree of the carbon host is essential for addressing issues that hamper commercialization of Li-S batteries,such as fast capacity decay and poor high-rate performance.In this work,highly ordered,ultrathin mesoporous graphitic-carbon frameworks(MGFs)having unique cage-like mesoporosity,derived from self-assembled Fe_(3)0_(4)nanoparticle superlattices,are demonstrated to be an excellent host for encapsulating sulfur.The resulting S@MGFs exhibit high specific capacity(1,446 mAh.g-1 at 0.15 C),good rate capability(430 mAh.g-1 at 6 C),and exceptional cycling stability(-0.049%capacity decay per cycle at 1 C)when used as Li-S cathodes.The superior electrochemical performance of the S@MGFs is attributed to the many unique and advantageous structural features of MGFs.In addition to the interconnected,ultrathin graphitic-carbon framework that ensures rapid electron and lithium-ion transport,the microporous openings between adjacent mesopores efficiently suppress the diffusion of polysulfides,leading to improved capacity retention even at high current densities.
