Long-Term Stability of Ni–Sn–Fe-Based Coatings Prepared by Electrodeposition for the Oxygen Evolution Reaction

Abstract

A coating comprising Ni, Sn, and Fe was deposited on a Ni mesh by cathodic polarization from a bath containing Ni2+, Sn2+, and Fe3+ salts in solution, and the oxygen evolution reaction properties of the thus obtained electrode were investigated. The lattice volume of the Ni–Sn–Fe-based coating was estimated to be 77.1 Å3, a much larger value than that (44.0 Å3) of the Ni–Fe-based coating obtained in the absence of Sn2+. The Ni–Sn–Fe-coated electrode manufactured by cathodic polarization at a current density of −120 mA cm−2 afforded a current density of 10 mA cm−2 at an overpotential of 276 mV in 1 M KOH. The said electrode’s Tafel slope was estimated to be 37 mV dec−1. When electrolyzed at constant current density (+50 mA cm−2 to +800 mA cm−2), it exhibited a stable potential for at least 162 h. The Ni–Sn–Fe-coated electrode was also used as the anode in a two-electrode cell (80 °C; 30 wt% KOH) and electrolyzed for 3 d. Evidence indicated a low cell voltage of 1.81 V at a current density of +600 mA cm−2, which is at an industrial level.