Oxygen Vacancies Engineering–Mediated BiOBr Atomic Layers for Boosting Visible Light‐Driven Photocatalytic CO2 Reduction

CO 2 photoreduction into valuable chemicals is a sustainable and prospective technology to alleviate greenhouse effects and the energy crisis. However, the photocatalytic efficiency is impeded by undesirable recombination of photogenerated carriers and poor CO 2 activation performance. Herein, oxygen vacancies (OVs) are introduced into BiOBr atomic layers by ultraviolet light assisting to increase the efficiency of carrier separation and CO 2 adsorption–activation performance, enhancing the CO 2 reduction activity. The introduction of OVs can effectively enhance the visible light absorption, boost the photogenerated carrier separation migration, and tune the adsorption/desorption process for CO 2 and products on the surface of photocatalysts. The optimized OVs engineering–mediated photocatalyst achieves a high CO generation rate of 10.15 μmol g −1 under visible light irradiation for 5 h in pure water, which is 1.99 times compared with that of pristine BiOBr atomic layers. The possible photocatalytic mechanism is investigated by in situ Fourier transform infrared spectroscopy (in situ FT‐IR) spectrometry. Also, an opportunity to design OVs‐rich ultrathin semiconductors for high‐performance CO 2 reduction is offered.