Glassy State Hydroxide Materials for Oxygen Evolution Electrocatalysis

Abstract

AbstractHydroxides are the archetype of layered crystals with metal‐oxygen (M‐O) octahedron units, which have been widely investigated as oxygen evolution reaction (OER) catalysts. However, the better crystallinity of hydroxide materials, the more perfect octahedral symmetry and atomic ordering, resulting in the less exposed metal sites and limited electrocatalytic activity. Herein, a glassy state hydroxide material featuring with short‐range order and long‐range disorder structure is developed to achieve high intrinsic activity for OER. Specifically, a rapid freezing point precipitation method is utilized to fabricate amorphous multi‐component hydroxide. Owing to the freezing‐point crystallization environment and chaotic M‐O (M = Ni/Fe/Co/Mn/Cr etc.) structures, the as‐fabricated NiFeCoMnCr hydroxide exhibit a highly‐disordered glassy structure, as‐confirmed by X‐ray/electron diffraction, enthalpic response, and pair distribution function analysis. The as‐achieved glassy‐state hydroxide materials display a low OER overpotential of 269 mV at 20 mA cm−2 with a small Tafel slope of 33.3 mV dec−1, outperform the benchmark noble‐metal RuO2 catalyst (341 mV, 84.9 mV dec−1) . Operando Raman and density functional theory studies reveal that the glassy state hydroxide converted into disordered active oxyhydroxide phase with optimized oxygen intermediates adsorption under low OER overpotentials, thus boosting the intrinsic electrocatalytic activity.