Single-atom-mediated electron islands boost photocatalytic CO₂ chemical fixation

Photocatalytic cycloadditions of CO₂ with epoxides are emerging as a significant platform for the green synthesis of valuable carbonates, where efficient catalytic systems with spatially separated charge carriers are demanded. Herein, a single p-block metal atom is proposed to be a candidate for photogenerated electron localization on a metal oxide substrate. By taking the Bi single-atom supported on ZnO nanosheet (Bi₁/ZnO) as an example, we show that the Bi atom plays the role of an electron island in the sea of delocalized holes within ZnO. Meanwhile, the as-formed electron island could readily promote the rate-determining ring-opening process of cycloaddition reactions. Benefiting from the unique spatially separated electrons and holes, the Bi₁/ZnO achieves a high yield of cyclic carbonates with almost 100% selectivity. This study provides a pioneering strategy for enhancing the performances of photocatalytic CO₂ chemical fixation.