The Controllable Preparation And Photocatalytic Performance Of Metal Sulfide Photocatalytic Materials

At present,the shortage of fossil energy and the deterioration of environmental quality are two major problems in today’s society,which have seriously affected the living environment of human beings.A large number of researchers have begun to realize that the development of clean renewable energy is imminent.Photocatalytic technology can convert abundant solar energy into efficient and clean energy.So it has been widely used.However,the core of photocatalytic technology is to find a suitable catalyst.Among many photocatalysts,metal sulfide and graphite carbon nitride（g-C₃N₄）have become the focus of research in the field of photocatalysis due to their outstanding performance.g-C₃N₄is simple to prepare,rich in source and has good thermal stability and chemical stability,but the traditional g-C₃N₄powder has some disadvantages of high photo-generated electron-hole recombination rate,poor photocatalytic performance and difficult recovery.In view of the above shortcomings,this study first introduced electrospun carbonized fibers（CNFs）as a carrier to solve the problem of difficult recycling.And then loaded different metal sulfides（Ag₂S,Zn S）in order to accelerate the transfer of charge at the contact interface and achieve the extension of g-C₃N₄catalytic performance from organic degradation to UV-visible photolysis of water to produce hydrogen.Metal sulfides such as CdS have become classic photohydrolytic hydrogen-generating materials because of their suitable band gap width and strong visible light absorption capacity.However,metal sulfide also has common shortcomings such as prone to agglomeration and severe photocorrosion.Based on the above problems,this study obtained the novel C/CdS hollow tube by adjusting the morphology and further compounded with the semiconductor g-C₃N₄to form a binary heterojunction.The synergy between structure and performance improved the stability of hydrogen evolution of CdS.Firstly,the carrier CNFs were obtained through electrospinning and high-temperature calcination technology.The g-C₃N₄/CNFs was obtained by melamine thermal polycondensation deposited on CNFs,and then Ag₂S and Zn S nanoparticles with uniform size were loaded by the hydrothermal reaction.Ag₂S@g-C₃N₄/CNFs and Zn S@g-C₃N₄/CNFs have been systematically analyzed their micromorphology,chemical composition and structure by a series of characterization methods.Under visible light irradiation,due to the limitation of Ag₂S bandgap structure,the modified Ag₂S@g-C₃N₄/CNFs composite only had good degradation ability and cycle stability for various dyes.Under ultraviolet irradiation,Zn S@g-C₃N₄/CNFs was used to the hydrogen production experiment of photolysis water using lactic acid as a sacrificial agent.Its catalytic performance and cycle stability were significantly better than g-C₃N₄/CNFs without adding any precious metals and achieved powder g-C₃N₄was modified by metal sulfide.Secondly,PAN polymer fiber membrane was prepared by electrostatic spinning technology,and then a simple one-step solvothermal method was used to obtain a novel C/CdS hollow tubular structure.The hollow tube was divided into two layers,the inner layer was CdS particles.And the solvent carbon wrapped in the outer layer will accelerate the electron transmission,and it also can protect the CdS from photocorrosion and improve the cycle stability of hydrogen production under ultraviolet-visible light.Thirdly,the C/CdS hollow tube was further modified.The carbon layer on the outside of the hollow tube was removed by calcination in an air atmosphere,and then g-C₃N₄was coated outside of the hollow tube by the vapor deposition method to obtain the g-C₃N₄/CdS composite.The formation of g-C₃N₄@CdS binary heterojunction was confirmed by TEM and XPS characterization.Due to the effect of heterojunction,the modified composite catalyst had better hydrogen production performance and stability under visible light.