Self-Supported Stainless Steel Nanocone Array Coated with a Layer of Ni–Fe Oxides/(Oxy)hydroxides as a Highly Active and Robust Electrode for Water Oxidation

Highly efficient, robust, and cheap water oxidation electrodes are of great significance for large-scale production of hydrogen by electrolysis of water. Here, a self-supported stainless steel (SS) nanocone array coated with a layer of nanoparticulate Ni–Fe oxides/(oxy)hydroxides was fabricated by a facile, low-cost, and easily scalable two-step process. The construction of a nanocone array on the surface of an AISI 304 SS plate by acid corrosion greatly enlarged the specific surface area of the substrate, and the subsequent formation of a layer of Ni–Fe oxides/(oxy)hydroxides featuring the NiFe2O4 spinel phase on the nanocone surface by electrodeposition of [Ni(bpy)3]2+ significantly enhanced the intrinsic activity and the stability of the SS-based electrode. The as-prepared electrode demonstrated superior activity for the oxygen evolution reaction (OER) in 1 M KOH, with 232 and 280 mV overpotentials to achieve 10 and 100 mA cmgeo–2 current densities, respectively. The high activity of the electrode was ...