Study On Photocatalytic Hydrogen Production Properties Of Modified G-C₃N₄ Loaded MOF-derived TiO₂ Nanocomposites

With the continuous development of human society,new clean energy and clean energy conversion methods are given higher requirements and expectations.The solar energy has attracted much attention due to its inexhaustible and inexhaustible cost.However,the use of solar energy has some problems,such as low energy density,poor stability,difficult to store and transport.Converting solar energy into hydrogen energy which has higher energy density,and is,easier to store and transport,shows a good application prospect in the field of new energy applications.Therefore,photocatalytic decomposition of water to hydrogen technology,as a reaction process and product can meet the demand that new energy should be clean,green and sustainable,and has become a hot spot in the field of energy research.g-C₃N₄ is a kind of non-metallic polymer semiconductor material which has attracted much attention in the field of catalysis in recent years.It has many advantages,such as suitable energy band structure,low cost,non-toxic and so on,which reflects the unique application potential.However,the photocatalytic carrier recombination rate is high and the active sites are few.It needs to be supported with precious metal co-catalyst to enhance its catalytic activity,and the utilization rate of visible light cannot meet the requirement of applications,which still directly restricts its practical application in production and life.In this paper,the MOF-derived TiO₂ nanoclusters were prepared by the template method of metal-organic frameworks?MOF?as modification materials.The MIL-125derived TiO₂ nanoclusters with large specific surface area are prepared by solvothermal method and calcined in air.On this basis,the preparation process,photocatalytic hydrogen production performance and influencing factors of MOF-derived TiO₂/g-C₃N₄ composite photocatalyst are systematically studied.In addition,in-situ modification of MOF-derived TiO₂/g-C₃N₄ composite photocatalyst by ammonia was used to treat the photocatalyst,and its photocatalytic properties and reaction mechanism are systematically studied.The researchs show that the loading of MOF-derived TiO₂ significantly reduces the recombination rate of photogenerated carriers and improves the hydrogen production activity of the composites.What's more,by means of vacuum packaging technology,the modification effect of ammonia gas,a by-product released from g-C₃N₄precursor dicyandiamide during thermal polymerization,on the product was realized.The by-product ammonia gas of thermal polymerization was in-situ applied to the modification of composite Photocatalysts in many aspects.The obtained composite photocatalyst has been modified from crystal structure,specific surface area and atomic doping,so that it has good visible light absorption capacity,and forms a visible-light-driven type ? heterojunction structure,which effectively separates photogenerated carriers and improves the photocatalytic hydrogen production performance.