Hierarchical Urchin-like Spinel CuxCo3-xO4 Particles as Oxygen Evolution Reaction Catalysts in Alkaline Medium

Abstract

Abstract In this work, spinel CuxCo3-xO4 (x = 0.00, 0.50, 1.00, 1.50) was synthesized through a typical ethanol-assisted hydrothermal route. The effect of the incorporation of copper on the resulting morphology, structure, and oxygen evolution reaction (OER) activity of the spinel Co oxides was investigated. In general, Cu-doped samples exhibited improved OER activity associated to the reduction of electrical resistivity of the spinel due to the presence of Cu2+ into the lattice. Further, the ionic bonding of OH− with Cu2+ is weaker relative to the Co3+ ions at the octahedral sites, which could have facilitated OER better. Among the Cu concentration experimented, Cu0.5Co2.5O4 exhibited the best OER catalytic with an onset overpotential and Tafel slope of about 271 mV and 100.4 mV·dec−1, respectively. This is attributed to its better conductivity due to the absence of a resistive secondary CuO phase.