Study On Photocatalytic Hydrogen Production Properties Based On Nano-Bi₂S₃ Heterostructure

With the shortage of fossil energy resources and the increasing global environmental problems of environmental pollution,it is urgent to look for efficient,clean and renewable energy that can replace fossil energy.Hydrogen energy is recognized as a clean energy that is not harmful to the environment,and the search for efficient hydrogen production technology has become an upsurge.Photocatalytic decomposition of water to produce hydrogen is a technology that uses inexhaustible solar energy to split water into hydrogen,and the conversion of abundant solar energy into chemical energy in the form of clean and renewable hydrogen fuel is a kind of available new energy.So far,more than 150 kinds of semiconductor photocatalysts for producing hydrogen by photolysis of water have been reported.However,there are still many problems that hinder the development of this technology and its large-scale application,such as:low solar energy utilization rate,rapid electronic recombination,low hydrogen production efficiency,poor cycle stability,and low quantum conversion rate,etc.In-depth understanding of the reaction mechanism of hydrogen production by photocatalytic hydrolysis,exploring the factors that affect the activity of hydrogen production by efficient photolysis of water,and using relevant theoretical rules to guide and design and develop high-efficiency photocatalysts are the key to breaking through this technical development bottleneck period.Bi₂S₃has received extensive attention because of its high solar energy utilization rate and high cycle stability.This article has carried out a series of research work on how to improve the hydrogen production efficiency of Bi₂S₃:1.Starting from the microscopic morphology,four kinds of Bi₂S₃photocatalysts with different morphologies were designed and synthesized,and their photocatalytic hydrolysis hydrogen production performance was studied.Based on the hydrothermal method,four different shapes of Bi₂S₃nanomaterials were synthesized by adjusting the reaction time and reaction raw materials.The photocatalytic hydrolysis hydrogen production test shows that nanotubes have better hydrogen production activity than nanowires,nanorods,and nanoflowers.The hydrogen production rate is 342μmol/h/g,and the cycle stability is also good.It has been analyzed through a series of XRD,SEM,TEM,BET,UV-Vis and other characterization methods.The data shows that Bi₂S₃can effectively absorb and utilize the energy in the near-infrared light region of solar energy,and has a strong light response capability;nanotubes The larger specific surface area provides more active sites for the catalytic reaction,so its photocatalytic effect is relatively best.2.The interface transfer mechanism of nested p-p-type semiconductor heterojunction composites is discussed,and on this basis,a series of Bi₂S₃@Cu₂O heterojunction composites are synthesized to promote the separation and migration of electron holes and improve photocatalysis Active purpose.By adjusting the loading of Cu₂O,Bi₂S₃@Cu₂O heterojunction composites with different composition ratios and good solid-solid interface contact were successfully synthesized.When the loading of Cu₂O is 7%,the hydrogen production rate reaches 753μmol/h/g without precious metal loading,which is 2.5 times higher than that of pure Bi₂S₃nanowires.This recombination amount of 7%produces an optimized heterostructure interface ratio,which enables the light absorption and carrier utilization to reach a synergy optimal value.Through a series of XRD,SEM,TEM,XPS and other characterization methods,the structure,morphology and chemical state of the elements were studied.With the help of annealing treatment,the crystallinity of the material and the adhesion ability between Cu₂O and Bi₂S₃are further improved,the existence of heterojunction is ensured,and the cycle stability of the catalyst is improved.Further analysis of the interface charge transfer mechanism between the heterojunction interfaces found that the presence of a built-in electric field in the heterojunction promoted the separation and migration of carriers,which in turn improved the efficiency of hydrogen production by photocatalytic hydrolysis.