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

Abstract

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 μmol 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.