Preparation Of Graphene Composite Aerogels And Their Photocatalytic And Electrochemical Properties

Environmental pollution and energy shortages are issues that need to be resolved.Due to the catalytic properties of semiconductor photocatalysts and the excellent properties of graphene aerogel(GA),graphene aerogel-semiconductor photocatalyst can be regarded as an ideal material for environmental restoration.So far,the research on graphene aerogel-based composite photocatalysis is rarely involved.Therefore,based on the controlled synthesis of graphene aerogel,this thesis carried out the controllable preparation of GA composite photocatalyst by introducing different types of visible light photocatalysts(chalcogen compounds(Sb2X3(X=S,Se)nanowires)and bismuth-based semiconductors(CaBi2O4,Bi2Fe4O9)),investigated the performance of visible light photocatalytic degradation and discussed its possible catalytic mechanism.Then,based on the advantages of magnetron sputtering,vanadium nitride(VN)and molybdenum disulfide(MoS2)modified graphene composite aerogels were prepared,which exhibited excellent electrochemical performance and have broad applications in supercapacitors.The application prospects of this technology provide a feasible technology for the further development of other composite materials.The specific content is as follows:(1)Three-dimensional(3D)Sb2X3(X=S,Se)nano wires/graphene aerogel(Sb2X3/GA)composites were prepared by hydrothermal method,and the visible light catalytic degradation performance of Sb2X3/GA composites was studied.For representative pollutants,Sb2X3/GA shows high degradation efficiency and good cycle stability under visible light irradiation.Under 30 min of irradiation,the photodegradation efficiencies are about 94.5%,68.3%,85.0%,and 95.3%for MO,RhB,CV,and MB,respectively.The measured photocatalytic rate constant of Sb2X3/GA is significantly greater than that of the original Sb2X3 nanowires and other photocatalysts reported in the literature.The photoluminescence and electrochemical impedance spectroscopy measurements confirmed that the enhanced photodegradation activity can be attributed to the synergistic effect of Sb2X3 nanowires and graphene aerogels.These results provide an innovative strategy for designing 3D graphene aerogel-based visible light-responsive photocatalysts.(2)The CaBi2O4/GA and Bi2Fe4O9/GA were prepared by a two-step hydrothermal method.The structure characterization confirmed that the prepared CaBi2O4 and Bi2Fe4O9 were successfully doped into the graphene aerogel,evenly distributed between graphene sheets.The degradation performance of CaBi2O4/GA and Bi2Fe4O9/GA composite aerogels for organic dyes and antibiotics under simulated sunlight had been researched.The consequences demonstrate that under 330 min of visible light irradiation,when CaBi2O4/GA was used as a photocatalyst,the photodegradation efficiencies of MO,MB,and TC-HCl were 98.96%,97.92%,and 98.55%,respectively.The photodegradation efficiencies were 90.22%,71.8%,92.3%and 78.58%for MO,RhB,MB and TC-HCl with Bi2Fe4O9/GA as photocatalyst.The photodegradation efficiencies of CaBi2O4/GA and Bi2Fe4O9/GA were significantly higher than that of pure CaBi2O4 and Bi2Fe4O9.The improved photodegradability can be ascribed to the presence of graphene sheets in the aerogel,which effectively separates the photo-induced carriers.(3)VN and MoS2 films were successfully deposited in GA by magnetron sputtering,respectively,and the corresponding MoS2/GA and VN/GA composites were conveniently constructed.The electrochemical properties of the composites were tested by CV,GCD and EIS.The consequences demonstrate that the maximum specific capacitance of VN/GA is 236.5 F g-1 at 0.5 A g-1.After 1000 cycles,the specific capacitance retention of VN/GA is 91.8%.The specific capacitances of MoS2/GA at 0.5 and 1 A g-1 are 187.3 and 175.0 F g-1.The capacitance retention is 93.5%after 1000 cycles at 2 A g-1.The excellent electrochemical performance of VN/GA and MoS2/GA is attributed to the effective interface bonding between VN or MoS2 films and graphene sheets achieved by magnetron sputtering process,which provides a feasible technology for the further development of other GA-based composite materials.