Construction Of Heterojunction System For Semiconductor Nanomaterials And Study In Photocatalytic And Photoelectrocatalytic Performance

Photocatalytic hydrogen production and photocatalytic water splitting technologies are considered as a form of artificial photosynthesis,and it is an interesting and challenging research hot topic.So far,the photocatalystic and photoelectrocatalytic systems of semiconductor materials have attracted more and more attention.Therefore,the development and design of highly efficient semiconductor photocatalysts has become a hot topic of research.Simultaneously,effective charge separation and transfer in semiconductor materials is the key to photocatalystic and photoelectrocatalytic performance.In this paper,we adopted WO₃ and g-C₃N₄ semiconductor materials as the research goals.Aiming at improving the performance of photocatalysis and its photoelectrocatalysis,we used heterojunction construction and surface modification on the surface interface of these two materials.The main research contents of this paper are as follows:?1?WO₃ nanosheets was prepared by hydrothermal method.Based on this material,using secondary hydrothermal with Zn In₂S₄?ZIS?as loading material to obtain WO₃/ZIS heterojunction arrays as photoanode materials for photoelectrocatalytic water oxidation.The performance test reveals that the successful loading of ZIS makes its photocurrent increase obviously.According to the analysis of electrochemical impedance spectroscopy,the charge transfer resistance of the semiconductor bulk phase and the interface between the semiconductor bulk phase and the electrolyte is significantly reduced.Due to this heterojunction structure,the separation and transfer of photo-generated carriers are promoted,and the lifetime of the carriers is enhanced to improve the photocatalytic performance.?2?The surface electric field is formed by grafting silane molecules on the surface of WO₃/ZIS heterojunction material by chemical water bath dipping method,which further promotes the separation and transfer of charges.By adjusting the silane molecules with different amounts of modification,WO₃/ZIS/AESI photoelectrodes were obtained.A series of tests showed that the photocurrent density was significantly enhanced,the photoelectric conversion efficiency was improved and the initial potential was also reduced.The grafting of silane molecules can not only realize the separation and transfer of photo-generated carriers in the bulk phase,but also effectively suppress the recombination of electrons and holes on the surface,thereby promoting surface reactions and enhancing photocatalytic performance.?3?We prepared g-C₃N₄/Cd S heterostructure photocatalytic material by calcination method and photodeposition method,and supported Ni S oxygen-promoting catalyst on the surface by photodeposition method.By adjusting the photodeposition time of Cd S and Ni S,the g-C₃N₄/Cd S/Ni S composite material was obtained to achieve the best photocatalytic activity.The heterostructure of g-C₃N₄/Cd S realizes the rapid separation and transfer of photogenerated electrons and holes and improves the absorption of visible light and the utilization of sunlight,while the addition of Ni S support catalyst promotes the surface reaction and further strengthens the composite Photocatalytic performance.