Photoelectrochemical CO₂ Reduction via Cu₂O/CuFeO₂ Hierarchical nanorods photocatalyst

Abstract

Abstract Although cuprous oxide, Cu 2 O, has attracted attention as a promising p‐type semiconductor material for carbon dioxide reduction (CO 2 RR) photocatalysts, serious stability problems have always occurred due to photocorrosion. In this work, we fabricated hierarchical‐structured photocathodes with CuFeO 2 on Cu 2 O nanorods by spray pyrolysis and oxygen‐controlled heat treatment to improve the stability of Cu 2 O from a thermodynamic perspective. Field‐emission scanning electron microscopy, field‐emission transmission electron microscopy and X‐ray diffraction confirmed that the Cu 2 O/CuFeO 2 hierarchical nanorod structure was successfully fabricated. It was observed that the photocathodes show enhanced stability as the Fe content increases. Therefore, we report that the CuFeO 2 layer enhances the stability of the Cu 2 O nanorod photocathode. A photocathode with a Cu : Fe atomic ratio of 1.52 : 1 has a current density of 1.1 mA/cm 2 at 0.35 V RHE even after 10 linear voltage sweep repetitions, a decrease of only 8 % compared to the current density at the first sweep. Additionally, formate and acetate were produced during the CO 2 RR, exhibiting faradaic efficiencies (FEs) of 21.6 % and 68.6 %, respectively.