Construction of light-sensitive Cu2O/Fe2O3 heterostructures to promote photocatalytic CO2 reduction and photo-assisted charge storage†

Designing high-performance bifunctional materials for photo-assisted electrochemical charge storage and photocatalysis is challenging due to the difficulty in balancing electroactivity and photo-to-electric efficiency. Herein, copper foam (CF) supported three-dimensional nanoarrays (3D NAs) composed of copper oxide/iron oxide (Cu₂O/Fe₂O₃) heterostructures were constructed as bifunctional materials for the photocatalytic CO₂ reduction reaction (CO₂RR) and photo-assisted supercapacitors. These Cu₂O/Fe₂O₃ 3D NAs have demonstrated high electroactivity and good light adsorption with high photocurrent responses. As a result, the optimized Cu₂O/Fe₂O₃ photocatalyst delivered a high methane (CH₄) production rate of 38.6 μmol h⁻¹ g⁻¹ with good cycling stability for the CO₂RR. When used for photo-assisted supercapacitors, the optimized Cu₂O/Fe₂O₃ photoelectrode exhibited a maximum photo-capacitance of 595 F g⁻¹, delivering an enhancement of 17.3% over the capacitance obtained without light (507 F g⁻¹). This work provides a unique approach to utilizing light energy directly to promote electrochemical and photocatalytic properties.