Hierarchical Urchin-like Spinel Cu_xCo_3-xO₄ Particles as Oxygen Evolution Reaction Catalysts in Alkaline Medium

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.

Active sites and optimization of mixed copper-cobalt oxide anodes for anion exchange membrane water electrolysis

“…Bare Carbon Paper similar to the best values obtained in other equivalent studies in the literature [56,58,59].…”

“…In addition, this analysis reveals the development of small and broad anodic and cathodic features with a different intensity depending on the electrode thickness. In particular, they appear at approximately 500 mV and 300 mV vs. Ag/AgCl and they can be attributed to the Co(III)/Co(IV) and the reverse redox couples, oxidation and reduction respectively [19,56,57] . Note that they show highest intensities for 1.8-CuCoO-1700 sample inducing a shift on the onset potential for the OER for this sample to around 600 mV, sustaining a certain overpotential and/or a poorer electrocatalytic activity for this reaction.…”