Bimetallic-based CuxCo3−xO4 nanoparticle-embedded N-doped reduced graphene oxide toward efficient oxygen evolution reaction and hydrogen evolution reaction for bifunctional catalysis

Abstract

The fabrication of efficient electrocatalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is essential for hydrogen production to obtain sustainable renewable energy. Owing to the increase in chemical complexity, multimetallic catalysts provide flexibility to alter their electronic structure to attain high intrinsic catalytic activity via synergistic effects. In this study, bimetallic copper-cobalt oxide nanoparticles (CuxCo3−xO4 NPs) embedded on nitrogen-doped reduced graphene oxide (N-RGO) substrates are fabricated as catalysts for the OER and HER via a facile solution-hydrothermal synthesis. In the fabricated N-RGO-supported Cu-doped Co3-xO4 nanoparticle (CuxCo3−xO4 NPs@N-RGO) hybrid catalyst, the RGO sheet acts as a conductive network to promote electron transfer, thereby increasing the electrical conductivity of the catalyst. Additional active sites acting as bridged sites from the Cu and N dopants improve the catalytic activity, resulting in outstanding electrochemical activity for OER and HER. The optimal Cu0.35Co2.65O4 NPs@N-RGO catalyst exhibits an overpotential of 170 mV at 10 mA cm−2 for HER and a low overpotential of 270 mV for the OER in basic media, which are comparable to those of Pt/C and IrO2. The synthesized catalyst is a promising bifunctional catalyst for overall water splitting.