Preparation Of Copper Based Phosphide Catalysts And Study On Its Photocatalytic Performance

With the continuous development of human civilization,human’s demand and dependence on energy are becoming increasingly high.Fossil energy is currently the most consumed energy,which has also brought a series of problems such as energy crisis and environmental pollution.In this context,finding a low-cost and easy to manufacture clean energy has become the preferred way to solve the above problems.Solar energy is an inexhaustible and widely distributed energy source.Hydrogen is a clean,pollution-free,and high calorific energy source.Photocatalytic water splitting can be used to generate hydrogen,water is used as the proton source and photo-generated electron is used to react with H₂O to produce hydrogen.In recent years,researchers have proposed that alcohols can function as reaction substrates and receptors for photo-generated electrons and holes to simultaneously produce organic compounds and hydrogen in redox reactions.Cu₃P,a p-type semiconductor,has been applied in lithium-ion batteries,hydrogen evolution reactions,and photocatalytic reactions due to its stability,low cost,and ease of preparation.This article selects Cu₃P as the research object and synthesized Cu₃P nanoparticles,Cu₃P quantum dots,and cobalt doped Cu₃P quantum dots through morphology engineering and doping engineering methods.Cu₃P was compounded with three kinds of n-type semiconductor Zn In₂S₄ to construct a p-n type heterojunction.Then the photocatalytic performance was tested,and mechanism of photolytic hydrogen generation,photocatalytic conversion of alcohols to organic products were studied.The main research content and conclusions are as follows:（1）Cu₃P nanoparticles with a size of approximately 100 nm were synthesized by phosphating copper oxide（Cu O）nanoparticles.Cu₃P nanoparticles were loaded onto flower-like Zn In₂S₄ with sulfur vacancies to construct p-n type heterojunctions.The composite photocatalyst showed significantly increased activity in the photocatalytic water splitting reaction,with a hydrogen production rate of 7045 mol·g^-1·h^-1.This was attributed to the construction of p-n type heterojunctions and the introduction of vacancies,which enhanced the separation and migration efficiency of photo-generated carriers.（2）Cu₃P quantum dots with a size of approximately 5 nm were prepared by calcining phosphated copper chloride dihydrate（Cu Cl₂·2H₂O）.Cu₃P quantum dots were coupled with ultra-thin Zn In₂S₄ nanosheets doped with copper atoms to construct p-n type heterojunctions.The combination of photocatalytic hydrogen production and organic synthesis has become a major direction in the development of photocatalytic reactions.This chapter combined photocatalytic hydrogen production with photocatalytic oxidation of alcohols to produce organic products reactions,and designed a photocatalytic reaction using methanol as the reaction substrate,successfully converting methanol into hydrogen,formaldehyde,and ethylene glycol.Cu₃P quantum dots had a smaller size and more active sites than Cu₃P nanoparticles.Due to the formation of p-n heterojunction,the separation and migration efficiency of photo generated charge carriers was improved,further enhancing the photocatalytic reaction activity.（3）Cobalt atoms were doped onto Cu₃P quantum dots to prepare Co doped Cu₃P quantum dots（Co Cu P）.The p-n type Co Cu P/Zn In₂S₄ heterojunction was constructed by combining Co Cu P with Zn In₂S₄ nanosheets.The photocatalytic activity of the photocatalyst for the simultaneous generation of hydrogen and aldehydes or ketones by photocatalytic conversion of alcohols was investigated.Alcohols were used as acceptors for both photo-generated electrons and holes for photocatalytic reactions.The results showed that the photocatalyst exhibited good reaction activity in the photocatalytic reaction of various alcohols,successfully generating hydrogen and corresponding organic compounds.Among them,the photocatalyst showed the highest activity in the photocatalytic conversion of isopropanol,and the optimal ratio of hydrogen and acetone production in the composite sample reached 26.8 mol·g^-1·h^-1 and 1065.77μmol,respectively.The improvement of performance was attributed to the construction of p-n type heterostructure,which improved the charge separation efficiency,and the incorporation of cobalt atoms in Co Cu P provided a large number of active sites.Finally,based on the detection results of carbon free radical intermediates by EPR,the mechanism of the reaction was reasonably analyzed through theoretical calculations.