Zn Dopants Synergistic Oxygen Vacancy Boosts Ultrathin CoO Layer for CO 2 Photoreduction

Photoreduction of CO 2 without photosensitizers and scavengers runs into the development bottleneck for lack of excellent photocatalysts and ambiguous reduction mechanism. Herein, an ultrathin CoO layer containing Zn‐dopants and O‐vacancies (V o ‐Zn‐CoO) is designed as an archetype to explore the influence mechanism of Zn on O‐vacancies in ultrathin nanolayer for CO 2 photoreduction. DFT calculations illustrate that Zn‐dopants not only reduce formation barriers of *COOH and *CO intermediates, but also form π‐back‐bonding with *CO stimulating CH 4 evolution. Finally, V o ‐Zn‐CoO layer significantly enhances CO 2 photoreduction efficiency and CH 4 selectivity with 26.8 µmol g −1 h −1 (63.8%) compared to 7.2 µmol g −1 h −1 (23.6%) for CoO layer with O‐vacancies. Moreover, the synergistic effect of Zn and O‐vacancies benefits the stability of O‐vacancies in photocatalysts, achieving durable photocatalytic performance of V o ‐Zn‐CoO layer. This work manifests that the strategy of metal atoms synergistic O‐vacancies is effective to optimize CO 2 photocatalytic efficiency, selectivity, and stability of photocatalyst with O‐vacancies.