The Preparation And Properties Study Of Z-scheme Heterojunction Photocatalyst

With the rapid development of the times,many problems impairing human health and ecological balance also follow.Among many problems,the water pollution problem has aroused people’s great attention,and it is very important to find an efficient,low-cost,sustainable and environmentally friendly method to remove pollutants in the water environment.Photocatalysis has attracted much attention from researchers because of its advantages of cleanliness,efficiency and simplicity.This paper focuses on the effective removal of pollutants in water environment through the development of efficient composite photocatalyst.The construction of Z-scheme heterojunction can improve the separation efficiency of photogenic carriers,enhance the REDOX capacity of the active groups,and promote the light absorption performance,so as to improve the visible photocatalytic activity of the composite photocatalyst.The main research contents and conclusions are as follows:（1）Novel Z-scheme rGO/Bi₂S₃-Bi OBr heterojunction with tunable Bi OBr（102）exposure was prepared via one-step solvothermal method using GO solution as precursor of rGO and crystal facet controlling agent.The GO content has an obvious effect on the exposure of Bi OBr（102）facet.The exposure of Bi OBr（102）facet and Z-scheme charge transfer play synergistic roles in improving the redox ability of rGO/Bi₂S₃-Bi OBr heterojunction.The Z-scheme rGO/Bi₂S₃-Bi OBr heterojunction with tunable Bi OBr（102）exposure shows good photocatalytic performance in the photocatalytic degradation of o-nitrophenol（2NP）and photocatalytic reduction of hexavalent chromium（Cr（Ⅵ））due to the efficient generation of electrons and reactive oxygen species.In the single system of 2NP,the photocatalytic degradation efficiency was 92%,in the single system of Cr（Ⅵ）,the photocatalytic reduction efficiency was95%.For the mixed system of 2NP-Cr（Ⅵ）,the degradation efficiency of 2NP and the reduction efficiency of Cr（Ⅵ）reached 67%and 95%respectively.In addition,after five cycles,1%rGO/Bi₂S₃-10Bi OBr photocatalyst still showed high reusability and stability.（2）Nano flower-like Bi₂WO₆and nano flower sphere Zn In₂S₄were prepared by hydrothermal method,and then Zn In₂S₄was used as the substrate,Bi₂WO₆was grown on the surface of the flower ball by combining with hydrothermal and in-situ growth method.Z-scheme Zn In₂S₄/Bi₂WO₆heterojunction was synthesized by optimizing the content of Bi₂WO₆.The photocatalytic efficiency of ceftriaxone sodium and Cr（Ⅵ）was as high as 94%and 99%of the heterojunction material,respectively.The materials were characterized and tested by a series of characterization methods,such as X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）,scanning electron microscopy（SEM）,UV-Vis DRS,Time-resolved photoluminescence spectroscopy（TRPL）,fluorescence spectroscopy（PL）,BET specific surface area,photocurrent and EIS.This kind of composite photocatalyst have excellent photocatalytic performance due to its low recombination rate of photogenerated electrons and holes,the absorption of visible light can be effectively used,and resulting in excellent photocatalytic performance.