Modification Of Cadmium Sulfide Photocatalytic Material And Its Photocatalytic Mechanism

With the rapid development of human society,the problems of energy shortage and environmental pollution have attracted extensive concern in the society.To effectively solve these two key problems,researchers have developed a new technology by utilizing photocatalytic materials for hydrogen production from water splitting.Specifically,the photogenerated electrons from photoexcited semiconductor materials were employed for hydrogen evolution reaction.Among many N-type semiconductor catalysts driven by visible light,cadmium sulfide（CdS）due to inexpensiveness,easy preparation and suitable band gap（2.4 e V）,has been widely studied.However,the high photogenerated carrier recombination rate,poor electrical conductivity and serious photocorrosion of CdS greatly limit its large-scale application.Therefore,in this paper,to solve the above solution,a series of strategies,such as cocatalyst modification and doping,have been employed to significantly improve its photocatalytic activity.The research contents are as follows in detail:1.The photocatalytic mechanism research of the Ag₂S in situ grown on CdS.The Ag₂S/CdS photocatalyst was fabricated by combination with the solvothermal and impregnation methods.The experiment results revealed that the hydrogen production activity from water splitting of the obtained photocatalyst was nearly 7 times higher than that of pristine CdS.Additionally,the synergistic X-ray photoelectron spectroscopy（SI-XPS）and other characterization results demonstrated that the photoexcited electrons from CdS could be easily transferred to the Ag₂S,which served as a photoelectron acceptor,that can effectively promote the photogenerated charge migration for high-efficient hydrogen production from water splitting.2.Ag2S/Ni-CdS for efficient hydrogen production from water splitting.The Ni-CdS photocatalyst was prepared by a solvothermal method,which was then constructed on the Ag₂S nanolayers to obtain the Ag₂S/Ni-CdS photocatalyst.SI-XPS results declared that the photogenerated electrons from the Ag₂S/Ni-CdScould effectively transfer to Ag₂S,while the photogenerated holes transferred to the Ni sites.Benefiting from the effective separation of the photogenerated charges,the hydrogen production activity of the Ag₂S/Ni-CdSwas increased by about 50 times compared with that of the pristine CdS,accompanied by an improved stability,which may due to the rapidly transfer of photogenerated holes to the Ni sites for inhibiting the photocorrosion.This work provides a greatly significance for constructing efficient photocatalyst systems.