Metallic Gold-Incorporated Ni(OH)₂ for Enhanced Water Oxidation in an Alkaline Medium: A Simple Wet-Chemical Approach

The development of a highly efficient electrocatalyst for the oxygen evolution reaction (OER) with a lower overpotential and high intrinsic activity is highly challenging owing to its sluggish kinetic behavior. As an alternative to the state-of-the-art OER catalyst, recently, transition-metal-based hydroxide materials have been shown to play important roles for the same. Owing to the high earth abundance of various Ni-based hydroxide and its derivatives, these are known to be highly studied materials for the OER. Herein, we report a simple wet-chemical synthesis of metallic gold-incorporated (by varying the concentration of Au³⁺ ions) Ni(OH)₂ nanosheets as an active and stable electrocatalyst for the OER in 1 M KOH medium. The Au-Ni(OH)₂ (2) catalyst demanded a low overpotential of 288 mV to attain a geometric current density of 10 mA/cm² with a lower Tafel value of 55 mV/dec compared to bare Ni(OH)₂ with a lower mass loading of only 0.1 mg/cm². Tafel slope analysis reveals that the incorporation of metallic gold on the hydroxide surfaces could alter the mechanistic pathways of the overall OER reaction. It has been proposed that the incorporation of metallic gold over the Ni(OH)₂ surfaces led to a change in the electronic structure of the electroactive nickel sites (Jahn-Teller distortion), which favors the OER by electronic aspects.