Electrodeposition of Unary Oxide ona Bimetallic Hydroxide as a Highly Active and Stable Catalyst forWater Oxidation

For industrial-scale water electrolysis, development of a highly stable and active oxygen evolution reaction (OER) electrocatalyst is highly demanded. In this study, we report an efficient OER electrocatalyst of CeOx (unary oxide) and NiFe-OH (bimetallic hydroxide) electrochemically deposited on a macroporous nickel foam substrate. The synthesized electrocatalyst exhibits remarkably improved OER performance by reaching a current density of 100 mA cm–2 at a low overpotential of 280 mV, which is quite superior to that of most of the previously reported non-noble-metal-based OER electrocatalysts. Furthermore, the developed catalyst demonstrated a minor Tafel slope of 43.2 mV dec–1 with good stability under a large current at a continuous operation of 80 000 s in a strong alkaline electrolyte. Experimental observations revealed that the combination of CeOx and NiFe-OH accelerates the electroadsorption energies between the electrocatalyst surface and oxygen intermediates, considerably contributing to the OER e...