Modulating Charge Separation of Oxygen-Doped Boron Nitride with Isolated Co Atoms for Enhancing CO₂-to-CO Photoreduction

To alleviate the greenhouse effect and address the related energy crisis, solar-driven reduction of carbon dioxide (CO₂) to value-added products is considered as a sustainable strategy. However, the insufficient separation and rapid recombination of photogenerated charge carriers during photocatalysis greatly limit their reduction efficiency and practical application potential. Here, isolated Cobalt (Co) atoms are successfully decorated into oxygen-doped boron nitride (BN) via an in situ pyrolysis method, achieving greatly improved catalytic activity and selectivity to the carbon monoxide (CO) product. X-ray absorption fine spectroscopy demonstrates that the isolated Co atoms are stabilized by the O and N atoms with an unsaturated CoO₂N₁ configuration. Further experimental investigation and theoretical simulations confirm that the decorated Co atoms not only work as the real active center during the CO₂ reduction process, but also perform as the electron pump to promote the electron/hole separation and transfer, resulting in greatly accelerated reaction kinetics and improved activity. In addition, the CoO₂N₁ coordination geometry is favorable to the conversion from *CO₂ to *COOH, which shall be considered as a selectivity-determining step for the evolution of the CO products. The surface modulation strategy at the atomic level opens a new avenue for regulating the reaction kinetics for photocatalytic CO₂ reduction. © 2023 Wiley-VCH GmbH.