Metal-induced oxygen vacancies on Bi2WO6 for efficient CO2 photoreduction

Semiconductor-based photocatalysis for efficient solar energy conversion is an ideal strategy to tackle the growing global energy and environmental crisis. However, the development of photocatalysis is still limited by problems such as low utilization of visible light, low efficiency of charge transfer and separation, and insufficient reactive sites. Herein, Au nanoparticles (NPs) were deposited on the surface of Bi2WO6 by a one-step reduction method, which simultaneously induced the formation of oxygen vacancies (OVs) on the surface of Bi2WO6. The OVs concentration is found to be increased with the increase of Au loading. Au NPs and OVs improve the light absorption and facilitate the separation and transport of the photogenerated carriers. In addition, OVs act synergistically with the nearby metal active sites to optimize the adsorption energy of reactants on the catalyst surface, changing the adsorption form of CO2 molecules on the catalyst surface. The as-synthesized photocatalyst achieved a photocatalytic performance of up to 34.8 µmol g−1 h−1 of CO2 reduction to CO without sacrificial agent in a gas-solid system, which is 9.4 times higher than that of the pristine Bi2WO6. This work may further deepen our understanding on the relationship between metal NPs and OVs, and their combined role in photocatalysis.