Ultrastable and Efficient Visible-light-driven CO2 Reduction Triggered by Regenerative Oxygen-vacancies in Bi2O2CO3 Nanosheets.

Surface vacancies can exert positive impact on CO2 photoreduction activity, yet difficultly maintaining long-term stability. Herein, we first design a fast low-pressure ultraviolet light irradiation strategy for easily regenerating the nearly equivalent surface vacancies, thus concurrently optimizing CO2 photoreduction activity and stability. Taking the defective Bi2O2CO3 nanosheets as an example, nearly equal amount of oxygen vacancies can be regenerated under UV light irradiation. Synchrotron-radiation quasi in-situ X-ray photoelectron spectra disclose the Bi sites in the O-defective Bi2O2CO3 nanosheets can act as the highly active sites, which not only help to activate CO2 molecules, but also contribute to stabilizing the rate-limiting COOH* intermediate. Also, in-situ Fourier transform infrared spectroscopy and in-situ mass spectrometry unravel the UV light irradiation contributes to accelerating CO desorption process. As a result, the O-defective Bi2O2CO3 nanosheets achieve a stability up to 2640 h over 110 cycling tests and a high evolution rate of 275 μmol g-1 h-1 for visible-light-driven CO2 reduction to CO. This study offers a new way for developing sustainable CO2 reduction photocatalysts.