The Synergistic Promotion Effect of In-situ Formed Metal Cationic Vacancies and Interstitial Metals on Photocatalytic Performance of WO3 in CO2 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 WO3 via acid treatments, resulting from the migration of metal impurities in WO3. Characterizations of structures, components, photo-responsive and photoelectric properties identify the differences of WO3 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 CO2 reduction are enhanced with the high production rates of CO and CH4. Experimental characterizations of WO3 photocatalysts indicate the increased photoinduced electrons and photocurrent intensities, and the decreased electrochemical impedances. Theoretical simulations confirm the changes of electronic structures of WO3. The calculated band gaps of WO3 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.

Automated summary

Microstructure modulation of photocatalysts is an effective way to improve photocatalytic performances. However, the synergistic effect of metal cationic vacancies and interstitial metals on photocatalysts has not been widely studied. This research demonstrates the in-situ formations of metal cationic vacancies and interstitial metals in WO3 through acid treatments, resulting in enhanced photocatalytic activities. Experimental characterizations and theoretical simulations confirm the changes in electronic structures of WO3, contributing to the improvement of photocatalytic activities.