Cobalt−Iron Oxide Nanosheets for High-Efficiency Solar-Driven CO₂−H₂O Coupling Electrocatalytic Reactions

Solar-driven electrochemical overall CO₂ splitting (OCO₂S) offers a promising route to store sustainable energy; however, its extensive implementation is hindered by the sluggish kinetics of two key reactions (i.e., CO₂ reduction reaction and oxygen evolution reaction (CO₂RR and OER, respectively)). Here, as dual-functional catalysts, Co₂FeO₄ nanosheet arrays having high electrocatalytic activities toward CO₂RR and OER are developed. When the catalyst is applied to a complete OCO₂S system driven by a triple junction GaInP₂/GaAs/Ge photovoltaic cell, it shows a high photocurrent density of ≈13.1 mA cm⁻², corresponding to a remarkably high solar-to-CO efficiency of 15.5%. Density functional theory studies suggest that the Co sites in Co₂FeO₄ are favorable to the formation of *COOH and *O intermediates and thus account for its efficient bifunctional activities. The results will facilitate future studies for designing highly effective electrocatalysts and devices for OCO₂S.