Preparation And Photocatalytic Properties Of Bi₂WO₆-based Nanomaterials

Photocatalysis technology has been widely studied for its fear of re-contamination,convenience and mild reaction conditions.In the field of photocatalysis,Bi₂WO₆ has been found to have high electron and hole recombination rates and low visible light utilization.Therefore,the photocatalytic performance of Bi₂WO₆ catalyst should be further improved.In this work,La³⁺doped Bi₂WO₆ material was prepared by hydrothermal method,and on this basis,heterojunctions were constructed with Cd S quantum dots to improve the photocatalytic performance of Bi₂WO₆.The samples were characterized by XRD,SEM,BET,XPS and PL,and the photocatalytic performance was evaluated by degradation of Rh B.The main research contents and results are as follows:（1）Three kinds of Bi₂WO₆ photocatalysts with different morphologies were prepared by hydrothermal method and template method,which were bulk,granular and nano-flake respectively.According to the degradation efficiency of Rh B by Bi₂WO₆,the two-dimensional nanosheet has high photocatalytic performance,with a photodegradation rate of 90%within 150 min.This is mainly due to the fact that the nanoparticle has a narrower band gap,which effectively promotes the separation of electron-hole pairs and thus has a higher photocatalytic activity.（2）La-Bi₂WO₆ nanosheet photocatalyst was prepared by hydrothermal method,and its optical properties and photocatalytic activity were analyzed.A small amount of La³⁺doping has an inhibitory effect on electron-hole pair recombination,and the increase of photogenerated carrier enhances its photocatalytic activity.Under simulated solar illumination,2%La-Bi₂WO₆ can degrade 98%of Rh B within 90 min.The possible degradation mechanism of La-Bi₂WO₆ was proposed through the combination of a free radical capture experiment and theoretical calculation.·O₂^-and holes are the main active substances in photocatalytic degradation.The improvement of photocatalytic performance was mainly due to La³⁺doping,which provided additional holes to participate in the degradation reaction.（3）Cd S QDs/La-Bi₂WO₆（CS/LBWO）heterojunction photocatalytic materials were prepared by hydrothermal method.The results show that compared with 2%La-Bi₂WO₆,CS/LBWO has a larger specific surface area and narrower band gap,which promotes electron and hole migration and effectively improves photocatalytic performance.Light degradation of Rh B,5%CS/LBWO degradation efficiency is the highest,in 70 min can degrade 99%of Rh B,the degradation efficiency has been greatly improved.At the same time,combined with the free radical capture experiment,XPS analysis,and differential charge density calculation results,it can be seen that electrons mainly transfer from the surface of La-Bi₂WO₆ to the surface of Cd S,forming a Z-type heterojunction,which increases the transfer rate of electrons,and thus improves the degradation performance of La-Bi₂WO₆catalyst.·O₂^-and holes play an important role in the degradation of pollutants.