Mn Single-Atom Photocatalyst Enables Efficient Photocatalytic Reduction of CO2

Photocatalytic conversion of CO2 into fuels with H2O as a proton source is recognized as a promising strategy for CO2 utilization. However, past efforts have mainly been devoted to the CO2 reduction reaction and overlooked essential water dissociation that provides a proton source. Herein, the Mn1/PCN-NV photocatalyst with Mn–N3 coordination by incorporating Mn single atoms into a polymeric carbon nitride (PCN) framework endowed with nitrogen vacancies (NV) is developed for CO2 photoreduction. It is revealed that NV induces an unsaturated environment for coordinating the Mn single atoms, which results in a highly localized surface electron distribution to promote charge carrier dynamics. The Mn sites simultaneously facilitate the dissociation of H2O and the activation of CO2, which are favorable for the formation of the key intermediate *COOH. The designed photocatalyst demonstrates a significantly improved CO production rate of 29.63 μmol g–1 h–1.