A universal electrochemical activation enabling lattice oxygen activation in nickel-based catalyst for efficient water oxidation

Abstract The electrocatalytic oxygen evolution reaction (OER) activity of transition metal (TM) based catalysts is predominantly governed by the reaction pathway since the activity contribution from lattice oxygen mechanism (LOM) is not limited by the conventional scaling relationship in the adsorbate evolution mechanism (AEM). Herein, we report a simple and robust electrochemical activation strategy that can generate abundant oxygen vacancies in nickel oxyhydroxide (NiOxHy) by reducing the intrinsic surface high-valence Ni3+ in a short time, endowing NiOxHy with an enhanced surface water adsorption, fast charge transfer kinetics, and in particular a distinct pH-dependent OER activity. The electrochemically activated NiOxHy exhibits an overpotential of 327 mV at 10 mA cm-2 and Tafel slope of 48 mV dec-1, which outperforms the pristine NiOxHy. This work therefore provides a viable route to regulating the local defects and electronic structure at the electrocatalyst surface to engineer high-performance TM based electrocatalysts.