Construction Of Photocatalytic Composite Systems Based On Transition Metal Sulfide/Carbides As Cocatalysts And Their Performances

With the continuous development of human society,traditional fuels such as coal and oil have been exhausting,and also caused serious environmental pollution problems.How to make highly efficient photocatalyst for the use of solar energy has become a hot topic.Since most photocatalyst have some disadvantages,such as fast recombination of photoinduced charge carriers and narrow light response range,they often exhibited unsatisfactory photocatalytic activities.Appropriate co-catalyst loading on the photocatalyst can promote or accelerate the photocatalytic process.However,the currently used co-catalyst is scarce and expensive precious metals,limiting their widespread applications.Therefore,the development of abundant,inexpensive,and excellent co-catalysts has become a hot topic.Bearing these considerations,the purpose of this thesis is to design and synthesize the co-catalyst based on the transition metal sulfide or carbide,and further to combine with energy band matched photocatalysts to form photocatalytic composite systems,so as to obtain the improved photocatalytic properties and explain the relevant intrinsic reasons.The main contents are as follows:1.An effective hydrothermal method was developed to construct MoS₂nanosheets/CdS nanocrystals photocatalytic composite systems.Such composites bear the nanocrystal-on-nanosheet heterostructures,ensuring the intimate interfacial contact and increased charge transfer kinetics.The resulting CdS/MoS₂ composites exhibit highly efficient photoreactivity and excellent photostability for hydrogen evolution under visible light irradiation.The hydrogen generation rate achieved by the optimal CdS/MoS₂ is approximately 286 times higher than that of pure CdS.This remarkably boosted performance could be ascribed to synergistically interfacial effect.2.The bamboo-like Co-Mo₂C@NC/g-C₃N₄ photocatalytic composite systems were constructed by a facile self-assembly.Such composites have nanotube-on-nanosheet structure,which exhibited high performance in photocatalytic water splitting with a rate up to 349?mol g^-11 h^-1.The results indicate that series of Co-Mo₂C@NC/g-C₃N₄ samples showed better hydrogen evolution activity than that of bare g-C₃N₄.The enhanced performance would be attributed to the co-catalytic effect of Co-Mo₂C@NC.The good electron transportation ability of Co-Mo₂C@NC can efficiently promote the transfer,migration and separation of charge carriers on the interface.3.BiOBr was hydrothermally grown in situ on the Ti₃C₂ to form a photocatalytic composite system.The Ti₃C₂/BiOBr can completely decompose 10mg L^-1 of RhB within 30 min.The degradation efficiency of Ti₃C₂/BiOBr composite was higher than that of pure BiOBr.Ti₃C₂ acted as a co-catalyst provide the excellent electron transportation.