Study On The Modification Of Visible Light Catalyst Bi₂WO₆ And The Degradation Mechanism Of Pollutants

Heterogeneous visible-light-driven photocatalysis has shown great application prospects in sewage treatment,it can directly use solar energy to degrade a variety of pollutants and sterilize them.Recently,Bi-based photocatalysts such as Bi₂O₂CO₃,Bi₂WO₆,BiOI,BiPO₄,BiVO₄ and Bi₂MoO₆ have been widely studied.Among them,Bi₂WO₆ has received great attentions owing to its unique layered structure and preferable band composition.However,Bi₂WO₆ has a wide band gap and low absorption of visible light,resulting in low photocatalytic activity.Based on the advantages and disadvantages of Bi₂WO₆,improving its photocatalytic activity through modification under the premise of maintaining its good stability is a direction worth focusing on.Bi/Bi₂WO₆-R with Bi⁰ metal particles was successfully prepared by hydrothermal synthesis based on visible light catalyst Bi₂WO₆.The photocatalytic activity of Bi/Bi₂WO₆-0.6 after modification was 6 times that of Bi₂WO₆.By Raman spectroscopy?Raman?,electrochemical workstation and X-ray photoelectron spectroscopy?XPS?characterization methods prove successful Bi⁰ metal particles deposition in Bi₂WO₆ material surface,and a strong interface interaction is formed.The existence of Bi⁰ causes partial on the surface of Bi₂WO₆,which can capture electrons and inhibit the combination of electrons?e^-?and holes?h⁺?,so that e-and h+can effectively interact with pollutants,or interact with H₂O Or O₂ to form other active species.The results of trapping experiments showed that the active species of photocatalytic reactions were mainly holes?h⁺?,and some of the active species were superoxide radicals(O₂^·-).In order to further improve the catalytic performance of Bi₂WO₆,it was modified by non-metallic element doping method,and IR-Bi₂WO₆ was successfully prepared.Photocatalytic degradation of 2-chlorophenol?2-CP?as the target pollutant determined that I_0.3-Bi₂W0₆ had the best activity,and the degradation rate constant was up to 0.9240 h^-1,3.1 times higher than that of Bi₂WO₆.Firstly,I"replaced O^2-between Bi₂WO₆ layer,which increased the layer spacing of Bi2W06,inhibited electron arnd hole combination,and enhanced separation efficiency;Moreover,10,30-Bi2W06 degradation of pollutants in the progress of the main active species for holes.T insert changed the Bi³⁺,W⁶⁺ and O^2-charge distribution,adjust the valence band and conduction band potential of the Bi₂W0₆.I_0.30-Bi₂WO₆ valence band?VB?potential is more positive,the'h+has more strong oxidation ability,which is a factor for I_0.30-Bi₂W0₆ has higher activity;Finally,the BET surface area of I_0.30-Bi₂W0₆(66.7 m² g^-1)was 2.6 times that of Bi₂WO₆(25.2 m² g^-1), and the increase of BET surface area provides more active sites for the photocatalytic process.I_0.30-Bi₂WO₆ can completely removed a variety of pollutants,such as RhB,BPA,CIP,SMZ and phenol,indicating that I_0.30-Bi₂W0₆ was suitable for being applied in the degradation of different pollutants from wastewater.Based on visible light catalyst Bi₂WO₆,this study modified Bi₂WO₆ through different methods,which significantly improved the catalytic performance of Bi₂WO₆ on the basis of ensuring excellent stability.