The Synergistic Promotion Effect of In‐situ Formed Metal Cationic Vacancies and Interstitial Metals on Photocatalytic Performance of WO 3 in CO 2 Reduction

Microstructure modulation of photocatalysts is an effective way to improve photocatalytic performances. The synergistic effect of metal cationic vacancies and interstitial metals on photocatalysts is rarely studied. In‐situ formations of metal cationic vacancies and interstitial metals are achieved in WO 3 via acid treatments, resulting from the migration of metal impurities in WO 3 . Characterizations of structures, components, photo‐responsive and photoelectric properties identify the differences of WO 3 photocatalysts via different treatments. The presence of both metal cationic vacancies and interstitial metal impurities exhibits the positive synergistic effect in photocatalytic reaction. Photocatalytic activities in CO 2 reduction are enhanced with the high production rates of CO and CH 4 . Experimental characterizations of WO 3 photocatalysts indicate the increased photoinduced electrons and photocurrent intensities, and the decreased electrochemical impedances. Theoretical simulations confirm the changes of electronic structures of WO 3 . The calculated band gaps of WO 3 after acid treatment decrease and the defect energy levels form, which favor the separation and the transfer of photoinduced carriers for the promotion of photocatalytic activities. To utilize the dissolution difference of metals is feasible to fabricate metal cationic vacancies and interstitial metals simultaneously, an option for other metal‐containing photocatalysts with the in‐situ introduced impurities.