Construction And Photocatalytic Properties Of In₂O₃/ZnIn₂S₄ 2D Heterojunction

Energy and natural environment are two key factors affecting the progress of modern economy and technology.Since its discovery,photocatalytic technology is considered to have a very promising development prospect in effectively addressing future energy crises and addressing environmental pollution issues at the root.Among many photocatalysts,the excellent photochemical stability and low toxicity make In₂O₃attract great attention.Although the band gap position of In₂O₃ meets the redox potential across CO₂ reduction and H₂O decomposition,with the discovery that In₂O₃material has many disadvantages such as poor light response in the visible light region,which greatly limits its further application in photocatalysis technology.Therefore,it is necessary to regulate and modify In₂O₃.Morphology and size control and heterojunction construction are the two most commonly used methods of photocatalyst modification.In the control of morphology and size,ultrathin two-dimensional materials have attracted great research interest because of their short carrier migration distance and more active sites.Selection of semiconductor composite materials with energy band position matching is crucial for designing and constructing target heterojunctions,and ZnIn₂S₄ with adjustable band gap（2.06-2.85 e V）and strong optical absorption ability has become the first choice.Based on this,the main work of this paper is as follows:（1）First,ultrathin In₂O₃ nanosheets were prepared by the optimized sol-gel method,and then ZnIn₂S₄ nanosheets were grown on the ultrathin In₂O₃ nanosheets,and the In₂O₃/ZnIn₂S₄ 2D/2D heterostructure was successfully constructed.The morphology,chemical composition and photoelectrochemical properties of In₂O₃,ZnIn₂S₄,In₂O₃/ZnIn₂S₄ were studied by various analytical methods.At the same time,the electron flow direction in the heterojunction In₂O₃/ZnIn₂S₄ was studied by^·OH capture experiment and surface photovoltage spectroscopy using terephthalic acid as fluorescence probe,which proved that it was a Type-II heterojunction.The construction of Type II heterojunction not only accelerates e^-and h⁺migration,but also integrates the advantages of In₂O₃ and ZnIn₂S₄.Therefore,Under the irradiation of visible light,In₂O₃/ZnIn₂S₄ showed excellent photocatalytic activity.The optimized heterojunction In₂O₃/ZnIn2S₄-40 photocatalysis can reduce CO₂ to produce CO at a rate as high as2585μmol g^-1 h^-1,while still maintaining good photochemical and structural stability after five cycles.（2）On the basis of ultrathin In₂O₃ nanosheets,RuO₂ was loaded to form In₂O₃/RuO₂ nanosheets,and then the ZnIn₂S₄ nanosheets were grown on the In₂O₃/RuO₂ as the carrier.The In₂O₃/RuO₂/ZnIn₂S₄ 2D/2D heterojunction with RuO₂as the electronic medium was successfully constructed.Implementation of means for characterizing the morphology and structure of materials and measuring their photoelectrochemical properties,it was proved that the prepared photocatalyst showed enhanced light absorption and large specific surface area,significantly improving its photocatalytic pure water decomposition performance.Under visible light irradiation,the optimized 1.5-In₂O₃/RuO₂/ZnIn₂S₄-15 catalyzes the decomposition of pure water to generate H₂ at a rate of up to 539.69μmol g^-1 h^-1,about 50 times of ZnIn₂S₄,about 25times of In₂O₃/ZnIn₂S₄-15.Finally,it is proved that 1.5-In₂O₃/RuO₂/ZnIn₂S₄-15 is an all-solid Z-scheme heterojunction through^·OH capture experiment.