Synergy of Fe dopants and oxygen vacancies confined in atomically-thin cobaltous oxide sheets for high-efficiency CO₂ photoreduction

Stumbled by the diversity and similarity of rction products, the artistic design of CO2 photocatalysts is complex. Herein, the well-designed CoO single-unit-cell layers collaborating O-vacancies-rich and Fe-dopants (V-o-Fe-CoO) are proposed as a prototype for exploring the relationship between O-vacancies/Fe-dopants and the photocatalytic performance. The Fe dopants and enough O vacancies contribute to the efficiency and product selectivity in the photoreduction of CO2, respectively. Through combined density functional theory (DFT) calculations and experiment, it was testified that introducing Fe-dopants in CoO single-unit-cell layers can convert the absorption of CO2 from an endoergic step to exoergic process and lower the energy barrier of the rate-determining step for forming CH4 to increase the catalytic efficiency. Moreover, designing O-vacancies can increase the desorption energy of CO and reduce the desorption energy of CH4, mainly facilitating the selectivity to form CH4. As expected, V-o-Fe-CoO guarantees high CO2 photoreduction efficiency (52.5 mu mol g(-1) h(-1)) and excellent CH4 selectivity (91.4%). This work uncovers the influence of multiple collaborating active sites in single-unit-cell layers for CO2 photoreduction performances, providing a new perspective for photocatalyst design.