Preparation Of Two-dimensional Nickel-based Compounds-modified ZnCdS Nanostructures And Their Photocatalytic Hydrogen Production From Water Splitting

Due to the increasing consumption of traditional energy sources by mankind,the development of renewable energy sources has attracted a great deal of attention from all countries.Hydrogen energy is currently one of the most promising alternatives to traditional fossil fuels.The use of photolytic hydrogen is one of the important ways to be able to convert solar energy into hydrogen energy,and ZnCdS solid solutions are receiving increasing attention in the visible light-catalyzed decomposition of hydrogen hydride due to their suitable band gap structure.However,due to its high-rate compounding of photoexcited carriers,it still faces significant challenges in practical applications.To address this issue,in this thesis study,a novel two-dimensional/zero-dimensional nickel-based compound/ZnCdS composite photocatalytic material was prepared by anchoring a zero-dimensional ZnCdS solid solution on the surface of a two-dimensional nickel-based nanosheet using a liquid-phase method.The research in this paper is as follows:（1）Preparation of two-dimensional/zero-dimensional NiO/ZnCdS composites and study of their visible light-catalyzed decomposition of aquatic hydrogen.NiO nanosheets were prepared by calcination of Ni（OH）₂ in air.The two-dimensional/zero-dimensional NiO/ZnCdS composites were prepared by loading the zero-dimensional ZnCdS nanoparticles prepared by hydrothermal method onto their surfaces.Hydrogen production tests showed that the 5%NiO/ZnCdS composite had the best hydrogen production rate of 5042μmol·g^-1·h^-1,which was about 38.2 times that of pure ZnCdS.The improved hydrogen production performance of the two-dimensional/zero-dimensional NiO/ZnCdS composites was elucidated by electrochemical tests,UV absorption spectroscopy and fluorescence spectroscopy,mainly due to the effective separation and directional movement of the photogenerated charges in the photocatalyst in the built-in electric field of the p-n heterojunction,which effectively enhanced the photolytic hydrogen production performance.（2）Preparation of two-dimensional/zero-dimensional Ni Se₂/ZnCdS composites and their visible photocatalytic decomposition of aqua-hydrogen performance.Ni（OH）₂ was selenated by hydrothermal method and Ni Se₂ sheet structures were synthesized.The two-dimensional/zero-dimensional Ni Se₂/ZnCdS composites were prepared by compositing the ZnCdS nanoparticles prepared by precipitation method with Ni Se₂ nanosheets by liquid phase method.Photolytic hydrogen production tests showed that the 3%Ni Se₂/ZnCdS composite had the highest hydrogen production rate of 7779μmol·g^-1·h^-1,which was about 8.4 times that of the ZnCdS nanoparticles.Based on photoelectrochemical tests and X-ray photoelectron spectroscopy,it is proposed that Ni Se₂ nanosheets with metallic properties are used as co-catalysts to enhance the charge transfer rate of ZnCdS nanoparticles and provide a photocatalytic mechanism with abundant active sites.