Copper-Doped Cobalt Oxychloride for Efficient Oxygen Evolution Reactions in an Alkaline Medium

The development of cost-effective and stable cobalt-based electrodes for oxygen evolution reaction (OER) from water at a lower overpotential is a major challenge. In this work, we report the fabrication of cobalt-based oxychlorides and their substitution with copper to enhance stability and improve OER activity. The substation of Cu not only affects the overpotential but also suppresses the in situ conversion of Co2+ into Co3+ in an electrochemical environment. The synthesized material is characterized by powder X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray mapping, and X-ray photoelectron spectroscopy (XPS) analyses. The Cu center dot Co2(OH)3Cl requires an overpotential of 230 mV to obtain a current density of 10 mA cm-2 and a Tafel slope of merely 53 mV dec-1. Moreover, the binding energy of Co 2p in XPS is slightly shifted toward lower binding energy values due to the alteration of the cation distribution at the lattice when Cu2+ replaces Co2+.