Preparation And Photocatalytic Performance Of Bi₂WO₆-Based Composite Photocatalysts

Environmental pollution and energy shortage caused by rapid d evelopment of industrialization have become increasingly prominent.Researchers from various countries and regions have continuously increased their efforts to actively explore new methods to solve these problems.Semiconductor photocatalytic technology is a sustainable and environmentally friendly technology and has attracted widespread attention.Photocatalyst under sunlight can not only remove pollutants in water,but also decompose water to produce clean energy such as hydrogen.Among many photocatalysts,Bi₂WO₆is one of the typical Aurivillius oxides with a suitable band gap,special electronic structure,and low cost,and shows a good application prospect.But it is difficult for it to meet the above high photocatalytic requirements.Therefore,it is necessary to carry out photocatalytic modification to construct a Z-scheme system for increasing its ability to absorb and utilize sunlight,enhancing practical application value.In this paper,Bi₂WO₆-based nanomaterials were prepared by hydrothermal method.Morphology and optical properties of the samples were characterized by XRD,SEM,XPS,FT-IR,DRS,PL,EIS and other characterization methods.Photocatalytic degradation properties of pure Bi₂WO₆,Ag I/Bi₂WO₆and Ag I/Bi₂WO₆/Ag₃VO₄composites for different dyes were tested,respectively.Main research contents are as follow:（1）Bi₂WO₆nanoflowers were synthesized by one-step hydrothermal method using Na₂WO₄·2H₂O and Bi（NO₃）₃·5H₂O as raw materials.Photocatalytic degradation efficiency for different dyes under visible light was investigated.Results showed that the synthesized products have low degradation effects on Rh B,MB and MO dyes,and the efficiencyneeded to be further improved.（2）Ag I/Bi₂WO₆composite photocatalyst was successfully prepared by liquid deposition method.Photocatalytic degradation of rhodamine B showed that degradation efficiency of the composite photocatalyst was significantly improved.20%Ag I/Bi₂WO₆composite catalyst had 91%Rh B degradation efficiency within 30 minutes;PL,photocurrent,and EIS results found that the Ag I/Bi₂WO₆composite photocatalyst has a good interface transmission rate,and the maximum photocurrent of 2.6μA/cm².Free radical capture experiments show that improvement in photocatalytic efficiency is mainly due to the formation of the Z-scheme system.（3）Based on Bi₂WO₆nanoflowers,potassium iodide（KI）and sodium orthovanadate（Na₃VO₄）were using as the source of iodine and vanadate,respectively,and the Ag I/Bi₂WO₆/Ag₃VO₄ternary heterojunction catalyst was successfully prepared by one-step liquid deposition.The ternary composite catalysts with different molar ratios were obtained by adjusting the ratio of VO₄^3-and I^-.Degradation efficiencies show that the ternary composite catalysts has good universality,and the degradation efficiency for Rh B is 93%under the illumination for 5 min,and the rate is significantly higher than that of the Ag I/Bi₂WO₆Z-scheme.