Subnanometric Bismuth Clusters Confined in Pyrochlore-Bi Sn O Enable Remarkable CO Photoreduction.

The development of highly efficient photocatalysts for conversion of carbon dioxide (CO ) with water (H O) into chemical fuels is of great importance for energy sustainability and carbon resource utilization. Herein, we demonstrated a facile hydrothermal method for in situ construction of subnanometric Bi metallic clusters in pyrochlore-Bi Sn O frameworks, leading to the remarkable improvements of photocatalytic performances for CO reduction into CO in the absence of sacrificial reagent. More specifically, an outstanding CO evolution activity of 114.1 μmol g  h has been achieved, more than 20-fold improvement compared with the pristine Bi Sn O (5.7 μmol g  h ). Detailed experiments together with in situ characterizations reveal that the spatially confined Bi clusters could significantly promote charge-separation/electron-enrichment and adsorption/activation of CO molecules, which provides highly efficient reaction channels to facilitate the generation of *COOH intermediate as well as the subsequent desorption of *CO towards CO formation. These demonstrations provide an important knowledge for precise design and fabrication of highly efficient photocatalysts for CO conversion into solar fuels.