A facile way was used to synthesize Cu2O/reduced graphene oxide (rGO) composites with octahedron-like morphology in aqueous solution without any surfactant. TEM images of the obtained Cu2O/rGOs reveal that the Cu2O ...A facile way was used to synthesize Cu2O/reduced graphene oxide (rGO) composites with octahedron-like morphology in aqueous solution without any surfactant. TEM images of the obtained Cu2O/rGOs reveal that the Cu2O particles and rGO distribute hierarchically and the primary Cu2O particles are encapsulated well in the graphene nanosheets. The electrochemical performance of Cu2O/rGOs is enhanced compared with bare Cu2O when they are employed as anode materials for lithium ion batteries. The Cu2O/rGO composites maintain a reversible capacity of 348.4 mA?h/g after 50 cycles at a current density of 100 mA/g. In addition, the composites retain 305.8 mA?h/g after 60 cycles at various current densities of 50, 100, 200, 400 and 800 mA/g.展开更多
Needle coke is the starting material for manufacture of premium graphite electrode,which at present cannot be produced by SINOPEC and even other domestic refining enterprises so that the carbon producing plants inside...Needle coke is the starting material for manufacture of premium graphite electrode,which at present cannot be produced by SINOPEC and even other domestic refining enterprises so that the carbon producing plants inside China have to import a significant amount of high-quality needle coke every year.展开更多
In this work,we initially synthesized Sb2S3 with uniform flower-like structures via a facile hydrothermal method through the modification of the Sb source and pH value.Afterward,Sb2S3 with a nanosheet structure was su...In this work,we initially synthesized Sb2S3 with uniform flower-like structures via a facile hydrothermal method through the modification of the Sb source and pH value.Afterward,Sb2S3 with a nanosheet structure was successfully synthesized on reduced graphene oxide(Sb2S3@RGO).The flower-like Sb2S3 and the Sb2S3@RGO nanosheets were tested as the counter electrode(CE)of dye-sensitized solar cells,and the latter exhibited a higher electrocatalytic property than the former owing to the introduction of graphene.The results from electrochemical tests indicated that the as-prepared Sb2S3@RGO nanosheets possess higher catalytic activity,charge-transfer ability,and electrochemical stability than Sb2S3,RGO,and Pt CEs.More notably,the power conversion efficiency of Sb2S3@RGO reached 8.17%,which was higher than that of the standard Pt CE(7.75%).展开更多
The design and synthesis of high‐performance and low‐cost electrocatalysts for the hydrogen evolution reaction(HER),a key half‐reaction in water electrolysis,are essential.Owing to their modest hydrogen adsorption ...The design and synthesis of high‐performance and low‐cost electrocatalysts for the hydrogen evolution reaction(HER),a key half‐reaction in water electrolysis,are essential.Owing to their modest hydrogen adsorption energy,ruthenium(Ru)‐based nanomaterials are considered outstanding candidates to replace the expensive platinum(Pt)‐based HER electrocatalysts.In this study,we developed an adsorption‐pyrolysis method to construct nitrogen(N)‐doped graphene aerogel(N‐GA)‐supported ultrafine Ru nanocrystal(Ru‐NC)nanocomposites(Ru‐NCs/N‐GA).The particle size of the Ru‐NCs and the conductivity of the N‐GA substrate can be controlled by varying the pyrolysis temperature.Optimal experiments reveal revealed that 10 wt%Ru‐NCs/N‐GA nanocomposites require overpotentials of only 52 and 36 mV to achieve a current density of 10 mA cm^(−2) in 1 mol/L HClO4 and 1 mol/L KOH electrolytes for HER,respectively,which is comparable to 20 wt%Pt/C electrocatalyst.Benefiting from the ultrafine size and uniform dispersion of the Ru‐NCs,the synergy between Ru and the highly conductive substrate,and the anchoring effect of the N atom,the Ru‐NCs/N‐GA nanocomposites exhibit excellent activity and durability in the pH‐universal HER,thereby opening a new avenue for the production of commercial HER electrocatalysts.展开更多
We report a facile coagglomeration method for preparing graphene (G)/MgCl2‐supported Ti‐based Ziegler‐Natta catalysts. The effects of graphene feed ratio on catalyst morphology and ethylene polymerization behavior ...We report a facile coagglomeration method for preparing graphene (G)/MgCl2‐supported Ti‐based Ziegler‐Natta catalysts. The effects of graphene feed ratio on catalyst morphology and ethylene polymerization behavior were examined. The synthesized catalyst exhibited very high activity for ethylene polymerization. The resultant polyethylene (PE)/G nanocomposites showed a layered morphology, and the graphene fillers were well dispersed in the PE matrix. In addition, the thermal stability and mechanical properties of PE were significantly enhanced with the introduction of a very small amount of G fillers (0.05 wt%). This work provides a facile approach to the production o fhigh‐performance PE.展开更多
An atomic layer deposition (ALD) method has been employed to synthesize Fe3O4/graphene and Ni/graphene composites. The structure and microwave absorbing properties of the as-prepared composites are investigated. The...An atomic layer deposition (ALD) method has been employed to synthesize Fe3O4/graphene and Ni/graphene composites. The structure and microwave absorbing properties of the as-prepared composites are investigated. The surfaces of graphene are densely covered by Fe3O4 or Ni nanoparticles with a narrow size distribution, and the magnetic nanoparticles are well distributed on each graphene sheet without significant conglomeration or large vacancies. The coated graphene materials exhibit remarkably improved electromagnetic (EM) absorption properties compared to the pristine graphene. The optimal reflection loss (RL) reaches -46.4 dB at 15.6 GHz with a thickness of only 1.4 mm for the Fe3O4/graphene composites obtained by applying 100 cycles of Fe2O3 deposition followed by a hydrogen reduction. The enhanced absorption ability arises from the effective impedance matching, multiple interfacial polarization and increased magnetic loss from the added magnetic constituents. Moreover, compared with other recently reported materials, the composites have a lower filling ratio and smaller coating thickness resulting in significantly increased EM absorption properties. This demonstrates that nanoscale surface modification of magnetic particles on graphene by ALD is a very promising way to design lightweight and high-efficiency microwave absorbers.展开更多
The high surface energy of nanomaterials endows them a metastable nature,which greatly limits their application.However,in some cases,the degradation process derived from the poor stability of nanomaterials offers an ...The high surface energy of nanomaterials endows them a metastable nature,which greatly limits their application.However,in some cases,the degradation process derived from the poor stability of nanomaterials offers an unconventional approach to design and obtain functional nanomaterials.Herein,based on the poor stability of ZnSe-[DETA]0.5 hybrid nanobelts,we developed a new strategy to chemically graphitize and functionalize graphene oxide(GO).When ZnSe[DETA]0.5 hybrid nanobelts encountered a strong acid,they were attacked by H^+cations and could release highly reactive Se^2−anions into the reaction solution.Like other common reductants(such as N2H4·H2O),these Se^2−anions exhibited an excellent ability to restore the structure of GO.The structural restoration of GO was greatly affected by the reaction time,the volume of HCl,and the mass ratio between GO and ZnSe[DETA]0.5 nanobelts.By carefully controlling the reaction process and the post-processing process,we finally obtained several Se-based reduced GO(RGO)nanocomposites(such as ZnSe/Se-RGO,ZnSe-RGO,and Se-RGO)and various selenide/metal-RGO nanocomposites(such as Ag2Se-RGO,Cu2Se-RGO,and Pt-RGO).Although the original structure and composition of ZnSe[DETA]0.5 nanobelts are destroyed,the procedure presents an unconventional way to chemically graphitize and functionalize GO and thus provides a new material synthesis platform for nanocomposites.展开更多
基金Project (2014CB643406) supported by the National Basic Research Program of ChinaProject (2011FJ1005) supported by Major Special Project of Science and Technology of Hunan Province,China
文摘A facile way was used to synthesize Cu2O/reduced graphene oxide (rGO) composites with octahedron-like morphology in aqueous solution without any surfactant. TEM images of the obtained Cu2O/rGOs reveal that the Cu2O particles and rGO distribute hierarchically and the primary Cu2O particles are encapsulated well in the graphene nanosheets. The electrochemical performance of Cu2O/rGOs is enhanced compared with bare Cu2O when they are employed as anode materials for lithium ion batteries. The Cu2O/rGO composites maintain a reversible capacity of 348.4 mA?h/g after 50 cycles at a current density of 100 mA/g. In addition, the composites retain 305.8 mA?h/g after 60 cycles at various current densities of 50, 100, 200, 400 and 800 mA/g.
文摘Needle coke is the starting material for manufacture of premium graphite electrode,which at present cannot be produced by SINOPEC and even other domestic refining enterprises so that the carbon producing plants inside China have to import a significant amount of high-quality needle coke every year.
基金funded by the Tianjin science and technology support key projects(18YFZCSF00500)the National Science Fund for Distinguished Young Scholars(21425729)the National Natural Science Foundation of China
文摘In this work,we initially synthesized Sb2S3 with uniform flower-like structures via a facile hydrothermal method through the modification of the Sb source and pH value.Afterward,Sb2S3 with a nanosheet structure was successfully synthesized on reduced graphene oxide(Sb2S3@RGO).The flower-like Sb2S3 and the Sb2S3@RGO nanosheets were tested as the counter electrode(CE)of dye-sensitized solar cells,and the latter exhibited a higher electrocatalytic property than the former owing to the introduction of graphene.The results from electrochemical tests indicated that the as-prepared Sb2S3@RGO nanosheets possess higher catalytic activity,charge-transfer ability,and electrochemical stability than Sb2S3,RGO,and Pt CEs.More notably,the power conversion efficiency of Sb2S3@RGO reached 8.17%,which was higher than that of the standard Pt CE(7.75%).
文摘The design and synthesis of high‐performance and low‐cost electrocatalysts for the hydrogen evolution reaction(HER),a key half‐reaction in water electrolysis,are essential.Owing to their modest hydrogen adsorption energy,ruthenium(Ru)‐based nanomaterials are considered outstanding candidates to replace the expensive platinum(Pt)‐based HER electrocatalysts.In this study,we developed an adsorption‐pyrolysis method to construct nitrogen(N)‐doped graphene aerogel(N‐GA)‐supported ultrafine Ru nanocrystal(Ru‐NC)nanocomposites(Ru‐NCs/N‐GA).The particle size of the Ru‐NCs and the conductivity of the N‐GA substrate can be controlled by varying the pyrolysis temperature.Optimal experiments reveal revealed that 10 wt%Ru‐NCs/N‐GA nanocomposites require overpotentials of only 52 and 36 mV to achieve a current density of 10 mA cm^(−2) in 1 mol/L HClO4 and 1 mol/L KOH electrolytes for HER,respectively,which is comparable to 20 wt%Pt/C electrocatalyst.Benefiting from the ultrafine size and uniform dispersion of the Ru‐NCs,the synergy between Ru and the highly conductive substrate,and the anchoring effect of the N atom,the Ru‐NCs/N‐GA nanocomposites exhibit excellent activity and durability in the pH‐universal HER,thereby opening a new avenue for the production of commercial HER electrocatalysts.
基金supported by the National Research Foundation of Korea (NRF-2015R1D1A1A0161012)the National Natural Science Foundation of China (U1462124)~~
文摘We report a facile coagglomeration method for preparing graphene (G)/MgCl2‐supported Ti‐based Ziegler‐Natta catalysts. The effects of graphene feed ratio on catalyst morphology and ethylene polymerization behavior were examined. The synthesized catalyst exhibited very high activity for ethylene polymerization. The resultant polyethylene (PE)/G nanocomposites showed a layered morphology, and the graphene fillers were well dispersed in the PE matrix. In addition, the thermal stability and mechanical properties of PE were significantly enhanced with the introduction of a very small amount of G fillers (0.05 wt%). This work provides a facile approach to the production o fhigh‐performance PE.
文摘An atomic layer deposition (ALD) method has been employed to synthesize Fe3O4/graphene and Ni/graphene composites. The structure and microwave absorbing properties of the as-prepared composites are investigated. The surfaces of graphene are densely covered by Fe3O4 or Ni nanoparticles with a narrow size distribution, and the magnetic nanoparticles are well distributed on each graphene sheet without significant conglomeration or large vacancies. The coated graphene materials exhibit remarkably improved electromagnetic (EM) absorption properties compared to the pristine graphene. The optimal reflection loss (RL) reaches -46.4 dB at 15.6 GHz with a thickness of only 1.4 mm for the Fe3O4/graphene composites obtained by applying 100 cycles of Fe2O3 deposition followed by a hydrogen reduction. The enhanced absorption ability arises from the effective impedance matching, multiple interfacial polarization and increased magnetic loss from the added magnetic constituents. Moreover, compared with other recently reported materials, the composites have a lower filling ratio and smaller coating thickness resulting in significantly increased EM absorption properties. This demonstrates that nanoscale surface modification of magnetic particles on graphene by ALD is a very promising way to design lightweight and high-efficiency microwave absorbers.
基金This work was supported by the National Natural Science Foundation of China(21431006,51732011,21761132008 and 21805189)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(21521001)+3 种基金the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(CAS)(QYZDJ-SSW-SLH036)the National Basic Research Program of China(2014CB931800)and the Excellence and Scientific Research Grant from Hefei Science Center of CAS(2015HSC-UE007).This work was partially carried out at the Center for Micro and Nanoscale Research and Fabrication,USTC.Xu L is grateful for the funding support from China Postdoctoral Science Foundation(2018M630711 and 2019T120540)and the Natural Science Foundation of Guangdong(2018A030310617).
文摘The high surface energy of nanomaterials endows them a metastable nature,which greatly limits their application.However,in some cases,the degradation process derived from the poor stability of nanomaterials offers an unconventional approach to design and obtain functional nanomaterials.Herein,based on the poor stability of ZnSe-[DETA]0.5 hybrid nanobelts,we developed a new strategy to chemically graphitize and functionalize graphene oxide(GO).When ZnSe[DETA]0.5 hybrid nanobelts encountered a strong acid,they were attacked by H^+cations and could release highly reactive Se^2−anions into the reaction solution.Like other common reductants(such as N2H4·H2O),these Se^2−anions exhibited an excellent ability to restore the structure of GO.The structural restoration of GO was greatly affected by the reaction time,the volume of HCl,and the mass ratio between GO and ZnSe[DETA]0.5 nanobelts.By carefully controlling the reaction process and the post-processing process,we finally obtained several Se-based reduced GO(RGO)nanocomposites(such as ZnSe/Se-RGO,ZnSe-RGO,and Se-RGO)and various selenide/metal-RGO nanocomposites(such as Ag2Se-RGO,Cu2Se-RGO,and Pt-RGO).Although the original structure and composition of ZnSe[DETA]0.5 nanobelts are destroyed,the procedure presents an unconventional way to chemically graphitize and functionalize GO and thus provides a new material synthesis platform for nanocomposites.