Construction of CF@CuxO/CoFeO nanowire arrays with an optimized bandgap to facilitate photo-assisted electrocatalytic water splitting

Abstract

The unsatisfactory photoelectrochemical (PEC) performance of hydrogen/oxygen evolution reactions (HER/OER) for overall water splitting is predominantly due to poor light absorption, severe photocorrosion, and sluggish kinetics of photo-generated charge carriers. Herein, copper foam supported copper/iron/cobalt mixed oxides (CF@Cu_xO/CoFeO) in nanowire arrays (NAs) were constructed by an ion exchange method, in which Co is partially substituted by Fe. Benefiting from the electronic synergistic effects between Fe/Co nanoparticles and Cu_xO, the as-prepared CF@Cu_xO/CoFeO showed an optimized bandgap and exhibited enhanced electrocatalytic performance under light irradiation, where only 1.68 V was required to achieve a current density of 10 mA cm⁻² for overall water splitting. Furthermore, density functional theory (DFT) calculations reveal that the introduction of Fe and Co active sites significantly improves the intrinsic catalytic activity and reduces the adsorption energy for H₂O and *OH intermediates, thus greatly promoting the catalytic efficiency for the HER and OER.