Oxygen Vacancy Drives CoO Atomic Layers Directional Photoreduction of CO2 to CH4

Plagued by the dual challenges of energy scarcity and environmental pollution, photocatalytic CO 2 reduction has emerged as a vital engineering for collecting solar energy to convert CO 2 into renewable fuels. Herein, the ultrathin CoO atomic layers with varying concentrations of oxygen vacancies are designed to photoreduce CO 2 and explore the mechanism of oxygen vacancy for CO 2 photoreduction. Density functional theory calculations illustrate that the oxygen vacancy not only enhances the available photoelectrons efficiency of CoO structures by improving the absorption of solar light and promoting the surface separation of electron–hole pairs, but decreases the highest occupied molecular orbital of CO 2 and the potential barrier of *CO conversion to *CHO, driving the CO 2 directed photoreduction toward CH 4 . Finally, the rich‐oxygen vacancies CoO atomic layers significantly enhance the effective photoelectrons efficiency with 136.3 μmol g −1 h −1 compared to 44.6 μmol g −1 h −1 for 2D‐CoO atomic layers. Moreover, the CH 4 selectivity also rises from 39.4% to 72.4% through the regulation of oxygen vacancies. This work promotes the development of Co‐based semiconductors for CO 2 photocatalytic reduction, and elucidates the mechanism of oxygen vacancy for CO 2 photoreduction, which provides valuable insights for the design and optimization of similar photocatalysts in both experimental and theoretical domains.