Modification Of Cadmium Sulfide Photocatalytic Material And Its Photocatalytic Hydrogen Production Performance

The continuous progress and development of society is inseparable from the rapid urbanization and industrialization,which brings about energy crisis and environmental problems.Among the many countermeasures,to find clean,safe and renewable energy is generally considered to be one of the most important ways to solve these two problems.Solar energy is the cleanest energy,and the total amount of solar energy received by the earth’s surface in one hour can meet the total annual energy demand of the world.However,the conversion and storage of solar energy is a problem,and many schemes have been proposed to achieve this purpose.Among the many schemes,photocatalytic technology stands out.Photocatalytic technology can be utilized to convert solar energy to chemical energy,such as photocatalytic water splitting to produce hydrogen.As the core part of photocatalytic technology,photocatalyst has been studied intensively.As one of the most promising photocatalytic materials,CdS has the advantages of suitable energy band structure,high electron mobility,and the ability to respond to visible light.However,its application is limited by the low utilization rate of visible light and the existence of photocorrosion phenomenon.In order to solve these problems,improve the photocatalytic performance and chemical stability of CdS,this paper modified it by morphology control,cocatalyst loading and construction of heterojunction.The prepared materials were tested and characterized,and the corresponding results were analyzed.The specific research contents are as follows:（1）CdS with hollow sphere（CdS-HS）structure was synthesized and combined with CoN to form CoN/CdS-HS photocatalytic system.The special hollow spherical structure and cocatalyst CoN in the CoN/CdS-HS system increase the utilization of visible light,promote the separation and migration of photogenerated carriers,and greatly improve the photocatalytic performance of the materials.Under the same conditions,the hydrogen output of the optimized 15%CoN/CdS-HS was 4.57 times superior to that of the pristine CdS-HS.And its photocatalytic hydrogen evolution rate reaches 58.80 mmol·g^-1·h^-1 under visible light.After 25 hours of photocatalytic reaction,the 15%CoN/CdS-HS can still maintain excellent stability.（2）Carbon-nitrogen co-doped Co₃O₄（CN-Co O）was prepared by a simple method,and composited with CdS to form CN-Co O/CdS p-n type heterojunction.Due to the excellent electrochemical properties of CN-Co O and the built-in electric field generated after the formation of the p-n junction,the separation and migration of photogenerated carriers of the material are greatly promoted.The photocatalytic hydrogen production activity of the material after forming the heterojunction is significantly improved,where the hydrogen evolution rate of 15%CN-Co O/CdS under visible light reaches 64.36 mmol·g^-1·h^-1,which is 6.78 times that of pure CdS.After 30 h of cyclic hydrogen production experiment,it can still maintain high photocatalytic activity.