Preparation Of Ni(OH)₂/gC₃N₄/CdS Photocatalyst And Its Performance For Oxidative Coupling Of Benzylamine And Coupling Of Hydrogen Generation Research

Solar-driven hydrogen production over semiconductor nanomaterials in aqueous solution is considered as a promising way.At present,the quantum efficiency for photocatalytic overall water splitting into H2 and O2 is very low,so sacrificial agents are usually used to consume photogenerated holes and improve the efficiency of hydrogen production.It is a good strategy to use the selective oxidation reaction of organic matter to replace the use of sacrificial agent,which can not only promote the efficiency of photocatalytic H2 production,but also obtain high value-added oxidation products.It is important for the sustainable development of human beings.The preparation of photocatalyst is the key to realize the coupling reaction system.g-C3N4 is a cheap,easily prepared and visible-light responded material,which has a potential application prospect.It is very important to realize selective oxidation of organic matter and efficient hydrogen production by constructing appropriate energy band structure of g-C3N4 based heterojunction photocatalyst without expensive cocatalysts and regulating the interaction of the interface.To solve the above problems,the specific work carried out is as follows:Firstly,CdS-Ni(OH)2/g-C3N4 composite photocatalyst was synthesized by chemical impregnation and self-assembly method,and the g-C3N4,CdS,Ni(OH)2/g-C3N4,CdS/g-C3N4,and(Ni(OH)2-CdS)/g-C3N4 as reference samples were also synthesized and characterized in detail.It was found that in the synthesized ternary composite photocatalyst CdS-Ni(OH)2/g-C3N4,Ni(OH)2 nanowires and irregular bulk CdS nanoparticles were isolated deposited on the surface of two-dimensional layered g-C3N4.The introduction of a small amount of CdS and the loading of Ni(OH)2 nanowires increased the light absorption of g-C3N4 and inhibited the recombination of photocharges.Then,all the samples were applied to the reaction system of photocatalytic hydrogen production and selective oxidation of benzylamine under visible light irradiation at room temperature.The experimental results show that CdS-Ni(OH)2/g-C3N4 photocatalyst can realize the selective oxidation of hydrogen and benzylamine at the same time,and the product yield is stoichiometric.The selectivity of n-benzylenebutylamine is higher than 99%,which is much higher than that of the reference samples.Finally,we tested the stability of CdS and CdS-Ni(OH)2/g-C3N4 photocatalysts in coupling system of hydrogen production and benzylamine oxidation and in Na2S/Na2SO3 aqueous solution,respectively.Compared with the pure CdS,CdS-Ni(OH)2/g-C3N4 photocatalyst has good activity in both coupling reaction system and Na2S/Na2SO3 aqueous solution after six cycles of experiments.The stability of activity the coupling system is better than that of Na2S/Na2SO3 as sacrificial agent.These results show that the structure of catalyst and coupling reaction system have important effects on the stability of photocatalytic activity.This study is of great significance for the development of stable photocatalysis system which can obtain two kinds of high value products by using photogenerated electrons and holes at the same time.