Zn Dopants Synergistic Oxygen Vacancy Boosts Ultrathin CoO Layer for CO₂ Photoreduction

Photoreduction of CO2 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 CO2 photoreduction. DFT calculations illustrate that Zn-dopants not only reduce formation barriers of *COOH and *CO intermediates, but also form pi-back-bonding with *CO stimulating CH4 evolution. Finally, V-o-Zn-CoO layer significantly enhances CO2 photoreduction efficiency and CH4 selectivity with 26.8 mu mol g(-1) h(-1) (63.8%) compared to 7.2 mu mol 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 CO2 photocatalytic efficiency, selectivity, and stability of photocatalyst with O-vacancies.