Study On Preparation And Activity Of Two-dimensional Nanosheet Heterojunction Composite Photocatalyst

g-C₃N₄ is an ideal material for photocatalytic hydrogen evolution and pollutants degradation.However,g-C₃N₄ exhibits poor performance in hydrogen production due to low carrier transfer efficiency.Therefore,selecting a semiconductor with a matching energy band potential to couple with g-C₃N₄ forming heterojunction is an effective method to improve the separation efficiency of photo-generated charges.g-C₃N₄ ultra-thin nanosheets were prepared by proton acidizing thermal polymerization method.The chemical reduction method was used to synthesiaze the sandwich-structured PANI-Ag-CN Z-scheme photocatalyst which was stacked layer by layer with g-C₃N₄ and PANI ultra-thin two-dimensional nanosheets.Ag nanoparticles were embeded as interlayers,which acted as the charge transfer intermediate leading to annihilation of the holes of g-C₃N₄ and the electrons of PANI.The strong reductive electrons and strong oxidative holes can be left at the CB of g-C₃N₄ and the VB of PANI.PANI-Ag-CN photocatalyst exhibits an increased hydrogen evolution activity of 5048 ?mol·g^-1·h^-1,which is 43.52-fold and 58.02-fold higher than that of g-C₃N₄ and bulk g-C₃N₄,respectively.Z-scheme heterojunction achieves efficient hydrogen evolution.In further research,O-doped two-dimensional nanosheet compound photocatalyst MoS_2-x O_x/g-C₃N₄ was constructed by hydrothermal method.MoS_2-x O_x/g-C₃N₄ photocatalyst exhibits good ability in photocatalytic hydrogen evolution from water.This excellent performance is attributed to the doping of oxygen,which not only improves the intrinsic conductivity of MoS₂ nanosheets but also promotes the combination of hydrogen protons and photo-generated electrons on the catalyst surface.The hydrogen evolution rate of MoS_2-xO_x/g-C₃N₄ compound photocatalyst is 2240 ?mol·g^-1·h^-1,which is 19.31 times and 25.75 times greater than that of g-C₃N₄ and bulk g-C₃N₄,respectively.The reason is that twodimensional nanosheet stack was possessed large contact areas,short charge transfer paths and large number of active sites,which can greatly improve the photocatalytic hydrogen evolution of MoS_2-x O_x/g-C₃N₄ compound.Figure 48;Table 6;Reference 112.