Preparation of Bi/Bi2WO6 by H2 reduction method and its photocatalytic degradation performance
Bi/Bi2WO6 was prepared by H2 reduction method to reduce the introduction of impurities.The optimal H2 reduction conditions and the degradation mechanism and stability of Bi/Bi2WO6 as a photocatalyst were discussed.The results showed that Bi/Bi2WO6,prepared by reduction at 200 ℃ for 30 minutes,had the best photocatalytic properties,and its degradation rate could reach 69.7％after 240 minutes of illumination.The reasons for the enhanced photocatalytic activity of Bi/Bi2WO6 included:the surface plasmon resonance(SPR)effect enhanced the absorption of light with wavelengths ranging from 450-800 nm;the built-in electric field generated between BWO and metallic Bi promoted the separation of photogenerated electron-hole pairs;and the presence of oxygen vacancies reduced the bandgap and captured electrons that reacted with adsorbed oxygen to generate active groups·O2,which promoted the degradation of tetracycline hydrochloride(TCH).TCH was mineralized into inorganic small molecules by hydroxyl radicals(·OH),superoxide radicals(·O2-),and holes(h+).The contribution of these three active substances to the degradation of TCH was ranked in the descending order of·O2-,·OH,and h+.Bi/Bi2WO6 exhibited good stability during photocatalytic reactions,provided the sample was washed with ethanol 10 times before each cycle experiment.After three cycles,the degradation rate decreased from 69.7％to 63.58％,which was caused by a slight decrease in the number of oxygen vacancies.The results provide a new way for the in-situ reduction preparation of Bi/Bi2WO6 to enhance the absorption of visible light and promote the separation of photogenerated carriers.
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