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.