CdS-based Composite Catalysts Used For Photocatalytic Decomposition Of Water

Energy and environment are the eternal challenges facing humanity.The use of semiconductor materials to convert endless solar energy into clean hydrogen energy is considered to be one of the important ways to solve energy and environmental problems.CdS is a typical wide bandgap semiconductor and has a suitable bandgap,so it is widely used in photoelectrocatalysis.However,pure CdS exhibits very low photocatalytic activity due to the rapid recombination of photogenerated electron-hole pairs in the body and photo-corrosion problems under light irradiation.Therefore,in this paper,based on CdS semiconductor photocatalysts carrying other transition metal materials as cocatalysts to form binary/ternary composite catalytic materials,assessing the effect of each co-catalyst loading on the photocatalytic hydrogen production activity of CdS,and at the same time investigating the stability of the composite catalysts,further explore the possible photocatalytic decomposition of water to make hydrogen mechanism.The main job overview is as follows:(1)The metal phase 1T-MoS2 was prepared by lithium ion intercalation.Then the binary composite 1T-MoS2/CdS was successfully prepared by the ordinary hydrothermal method.The hydrogen production performance under different doping ratios was studied.The results showed that when the content of 1T-MoS2 reached 5 wt.%,the photocatalytic rate of hydrogen production was the highest,reaching 1195.8 pmol·h-1·g-1.(2)CoP was prepared by mild thermal phosphatization method and then mixed with CdS to obtain the binary composite material CoP/CdS,and the hydrogen production activity under different doping ratios was studied.The results showed that the photocatalytic rate of hydrogen production when the content of CoP reached 10 wt.%was 23.59 mmol·h-1·g-1,which was 57.54 times that of pure CdS and 3.30 times that of CdS-0.5%Pt.(3)NiS/CdS binary composites were prepared successfully by two-step ordinary hydrothermal reaction,and the effect of the loading ratio of NiS nanoplates on visible light catalytic hydrogen production activity of CdS was explored.The results show that the photocatalytic rate of hydrogen production is the highest when the content of NiS is 5 mol%,which is 12.80 mmol·h-1·g-1,which is 31.22 times that of pure CdS.(4)We have also implemented the RGO nanosheets and further explored the photocatalytic hydrogen production performance of the ternary composite NiS-CdS/RGO.The results showed that the photocatalytic efficiency of hydrogen production was the highest when NiS was 5 mol%and RGO was 1 wt.%,which was 14.96 mmol·h-1·g-1,exceeding their binary as a cocatalyst alone.It is 36.49 times that of pure CdS.Based on the changes in hydrogen production efficiency caused by various carriers,we proposed the possible photocatalytic hydrogen production mechanism of NiS-CdS/RGO.