Efficient Alkaline Water Oxidation Electrocatalysis Enabled via the Modulation of Sn‐containing Anions towards NiFe Oxyhydroxide

Abstract

Despite being considered as efficient non‐noble metal‐based electrocatalysts for alkaline oxygen evolution reaction (OER), NiFe (oxy)hydroxides (NiFeOxHy) typically fall short of meeting practical requirements. To address this challenge, herein, we introduce a facile in situ electrochemical incorporation technique to form Sn‐doped NiFe‐layered double hydroxide (NiFeSn‐LDH) precatalysts. Subsequently, under the alkaline OER process, the precatalyst evolves into stannate ion‐adsorbed NiFe oxyhydroxides (NiFeOOH). The presence of these stable stannate oxyanions plays a key role in mitigating Fe leaching, optimizing the electronic structure of NiFeOOH, and improving its reaction kinetics, thereby significantly enhancing alkaline OER performance. Notably, the nickel foam‐supported NiFeSn‐LDH demonstrated impressive results delivering a large current density of 100 mA cm−2 at an overpotential as low as ~260 mV and maintaining the industrial‐relevant ~500 mA cm−2 current density over 5 days with negligible activity decay, surpassing the performance of most of the transition metal‐based electrocatalysts. Comprehensive advanced characterization of the precatalysts, before and after the OER reactions, has been performed to uncover stable residual stannate ions at the surface of NiFeOxHy and to determine their pivotal role in promoting alkaline OER.