Atomic-level surface modification of ultrathin Bi2WO6 nanosheets for boosting photocatalytic CO2 reduction

Creating useful chemicals based on artificial CO2 photoreduction is considered to be an attractive approach to address the environmental and energy crises. Currently, its selectivity with high conversion efficiency is still a grand challenge. Here, we report the refined substitution of Bi3+ with Ag+ in ultrathin Bi2WO6 nanosheets through a liquid-phase cation exchange process, favoring a high selectivity towards the photocatalytic production of CO from CO2. The incorporation of Ag+ could not only significantly promote the adsorption of both CO2 and H2O molecules, but also facilitate the transfer of photogenerated carriers. The as-fabricated photocatalyst achieves a high CO generation rate of 116.96 μmol g−1 with a superb selectivity of 95.7 % after 6 h reaction without any sacrificial agent, approximate 4.2 times higher than that of pure Bi2WO6. The mechanism for photocatalytic CO2 reduction is proposed, based on in-situ Fourier Transform Infrared spectrometry analyses and Density Functional Theory calculations.