Engineering Cu2O/Cu@CoO hierarchical nanospheres: synergetic effect of fast charge transfer cores and active shells for enhanced oxygen evolution reaction

Abstract

A novel hollow core–shell Cu₂O/Cu@CoO nanosphere composed of a Cu₂O/Cu core and CoO shell was produced via a facile soft template method and a post-thermal annealing process. The formation of the Cu₂O/Cu metal/semiconductor core structure played a key role in increasing the conductivity and facilitated the fast charge transfer process during the electrochemical reaction. Engineering the chemical coupling of the active CoO shell provided a large surface roughness to the benefit of abundant adsorbed active OH⁻ species for the OER. The synergetic effect of the fast charge transfer cores and active shells enhanced the OER. By adjusting the raw ratio of Cu/Co to 1/2, Cu₂O/Cu@CoO exhibited the lowest overpotential of 330 mV at 10 mA·cm⁻². This facile chemical method, which coupled CoO nanoparticles with Cu₂O/Cu hollow spheres, could pave the way for controlling the fabrication of other core–shell binary transition metal oxide heterogeneous catalysts in electrochemical applications.