Electrodeposited Amorphous Tungsten-doped Cobalt Oxide as an Efficient Catalyst for the Oxygen Evolution Reaction

Thin film of amorphous tungsten-doped cobalt oxide (W:CoO) was successfully grown on a conducting electrode via an electrochemical oxidation process employing a [Co(WS₄)₂]²⁻ deposition bath. The W:CoO catalyst displays an attractive performance for the oxygen evolution reaction in an alkaline solution. In an NaOH solution of pH 13, W:CoO operates with a moderate onset overpotential of 230 mV and requires 320 mV overpotential to generate a catalytic current density of 10 mA cm⁻². A low Tafel slope of 45 mV decade⁻¹ was determined, indicating a rapid O₂-evolving kinetics. The as-prepared W:CoO belongs to the best cobalt oxide-based catalysts ever reported for the oxygen evolution (OER) reaction.