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 maintained over 340 h of chronopotentiometric test at 20 mA cmgeo 2, and the electrode also showed good stability over 100 h of electrolysis at high current density (200 mA cm 2) More important for practical application, the used SS based electrode can be easily regenerated with the original OER activity. The superior activity of this SS based electrode stems from synergistic combination of high conductivity of the SS substrate, a large electrochemically active surface area of the nanocone array, and a uniformly coated nanoparticulate Ni Fe oxide/(oxy)hydroxide layer with an optimal Ni/Fe ratio.
ACS applied materials interfaces