Mechanism Of Water Splitting In Photocatalytic Water Splitting System Of Ga-Zn/Ge-Zn Nitrogen Oxides

Under the background of the energy crisis,environmental pollution,and"carbon neutrality",people have increased the research and utilization of high-efficiency,pollution-free and renewable energy.Among them,solar energy has been studied by many scholars for a long time and widely because of its universal,huge,long-term and harmless advantages.At the same time,hydrogen energy has attracted more and more attention of scholars because of its clean and efficient characteristics.Photocatalytic water splitting to generate hydrogen and oxygen has successfully linked solar energy and hydrogen energy through photocatalysts.GaZnNO and Ge Zn NO solid solution photocatalysts have the performance of photocatalytic water splitting under visible light and have a controllable band gap of 2.3-2.8 e V,which are very promising photocatalysts.The current research mainly focuses on improving the photocatalytic water splitting performance of GaZnNO and Ge Zn NO through various methods,while the specific reaction mechanism in the photocatalytic water splitting reaction system has not been deeply studied.Therefore,in this experiment,the photocatalytic overall water splitting mechanism of two solid solution catalysts,GaZnNO and Ge Zn NO,was studied,in order to provide a theoretical reference for the further improvement of photocatalytic water splitting performance.In this experiment,two catalyst systems,GaZnNO and Ge Zn NO,were studied at the same time.Through the comparison and analysis of the two systems,some reaction mechanisms of photocatalytic water splitting were mutually confirmed.GaZnNO and Ge Zn NO catalysts were prepared by solid-state synthesis,and the catalysts were modified with Ru O₂ by hydrothermal method.Various characterizations of the catalysts were carried out by XRD,SEM,UV-vis-DRS,PL,and BET,and the information on the crystal structure,surface morphology,optical properties,and adsorption properties of the catalysts was obtained,which provided a direct reference for the subsequent experiments.Following,the possible intermediate product H₂O₂ was added to the photocatalytic water splitting system,and the changes of·OH and O₂ in the system were observed and analyzed,which preliminarily proved that H₂O₂ was an intermediate product generated by photocatalytic water splitting of oxygen.The Rh B degradation experiment shows that the correlation between·OH and the oxidative activity of the catalyst is small,indicating that·OH is a by-product in the photocatalytic water splitting reaction.By adding an electron consuming agent(Fe³⁺)to the photocatalytic water splitting system,more relevant information about the photocatalytic water splitting process was obtained,and the changes of·OH and O₂ were observed and analyzed,which further verified the initial speculation.The main research conclusions are as follows:（1）H₂O₂ is an intermediate product of oxygen generation in the photocatalytic overall water splitting process,and the·OH in the system mainly comes from the side reaction during the oxygen generation reaction.（2）Ru O₂ deposited on the catalyst surface significantly improves the photocatalytic water splitting performance.On the one hand,the recombination of photogenerated electrons and photogenerated holes is inhibited,providing a large number of hydrogen evolution sites for the migration and reaction of photogenerated electrons,thereby promoting the generation of hydrogen in the photocatalytic water splitting reaction.On the other hand,Ru O₂ has the ability to catalyze the conversion of H₂O₂ into oxygen,which can promote the rapid oxidation and decomposition of the intermediate product H₂O₂ to generate O₂,which greatly promotes the generation of oxygen in the photocatalytic water splitting reaction.Thus,the performance of photocatalytic overall water splitting is improved.（3）In the photocatalytic system of GaZnNO and Ge Zn NO,the oxidative ability in the photocatalytic reaction is mainly affected by photogenerated holes,and·OH as a by-product of water splitting has little effect on the oxidative degradation of organic matter.