Study On High Efficiency Photocatalytic Water Decomposition Catalyst Based On ZIF-67 Nanoskeleton Structure

Under the double pressure of energy crisis and environmental pollution,it is urgent to develop clean energy technology.As a kind of sustainable fuel with high calorific value and zero pollution,hydrogen energy is favored by the majority of scientific researchers.The photocatalytic decomposition of water to produce hydrogen,which converts solar energy into chemical energy,is considered as a promising strategy.Broadening the optical absorption range of photocatalyst and improving the separation efficiency and migration of photogenerated carrier are the keys to improve the performance of photocatalysis.The construction of heterojunction is recognized as one of the important means to promote the separation and migration of photogenerated electron-hole pairs.In addition,the design and preparation of composite photocatalysts based on material morphology and structure is also an important method to improve the photocatalytic performance.Among many photocatalysts,Zeolitic Imidazolate Framework 67（ZIF-67）,as a Co organic skeleton material,has a large specific surface area,multiple active sites and a unique skeleton structure,which makes it have a broad prospect in the application of photocatalytic hydrogen production.However,due to the shortcomings of ZIF-67’s poor conductivity and low visible light capture rate,the photocatalytic efficiency is still not satisfactory.Therefore,the design and preparation of composite photocatalyst based on ZIF-67 nanoskeleton structure has important research significance and application prospect.In this paper,based on ZIF-67,Co P,Co S_x and Co₃O₄ materials with specific skeleton structure were prepared by simple pre-treatment and post-treatment methods,and a series of superior performance composite photocatalysts were designed and developed respectively.The phase structure,morphology and light absorption characteristics of the composite photocatalyst were studied by systematic characterization and theoretical calculation.The photocatalytic activity and catalytic mechanism of the composite photocatalyst were also studied by photocatalytic hydrogen evolution test.Specific research contents are as follows:（1）Preparation of Co P-V_p@Cd_0.5Zn_0.5S composite photocatalyst modified with monatomic Phosphorus vacancy（V_p）and its photocatalytic properties for hydrogen evolution.A novel single-atom V_p modified Co P-V_p@Cd_0.5Zn_0.5S heterojunction photocatalyst was synthesized by hydrothermal phosphating hydrothermal strategy using ZIF-67 as template.Due to the construction of Schottky junction and the introduction of single atomic V_p,the separation and migration of photogenerated carriers are promoted.The Co P-V_p@Cd_0.5Zn_0.5S composite photocatalyst prepared by this method shows excellent photocatalytic performance and stability under visible light.（2）Preparation of core-shell Co S_x@In₂S₃ composite photocatalyst and its photocatalytic properties for hydrogen evolution.Co S_x@In₂S₃nanocomposite photocatalyst with hollow core-shell structure was prepared by hydrothermal method and oil bath method using ZIF-67 as template.The design of the hollow core-shell structure enhanced the light absorption of the composite photocatalyst,and the constructed type II heterojunction between the two accelerated the transport of photogenerated carriers and optimized the migration path of photogenerated electrons.The Co S_x@In₂S₃nanocomposite photocatalyst showed good photocatalytic activity.（3）Preparation of p-n junction Zn In₂S₄/Co₃O₄ nanocomposite photocatalyst and its photocatalytic properties for hydrogen evolution.Using ZIF-67 as template,Zn In₂S₄/Co₃O₄ composite photocatalyst was prepared in situ by hydrothermal-oxidation-hydrothermal strategy.Due to the tight binding mode between 2D/2D materials and the p-n heterojunction constructed between Zn In₂S₄ and Co₃O₄,the spatial separation and migration of photogenerated electron-hole pairs are accelerated,and the composite photocatalyst shows enhanced photocatalytic performance.