Electrodeposited Cobalt Stannide: A Highly Efficient Oxygen Evolution Reaction Catalyst

The oxygen evolution reaction is the most kinetically hindered process in water electrolysis. Thus, oxygen evolution catalysts are required to improve the reaction kinetics. Precious metal catalysts are highly active, but the raw materials are scarce and costly. Thus, catalysts based on earth-abundant elements have drawn attention, and high performance, low-cost, and practial catalysts have been reported. Of the precious-metal-free commercial electrocatalysts, cobalt oxides are among the most important, and their catalytic properties can be improved by incorporating other elements. In this paper, we report that electrodeposited cobalt stannide (CoSn2) is a highly efficient oxygen evolution electrocatalyst, showing long-term electrochemical stability under alkaline conditions. Under optimal conditions, the catalyst operates at overpotentials of 250 and 300 mV at current densities of 1 and 10 mA cm(-2), respectively, and has a Tafel slope of 64 mV dec(-1). Furthermore, the prepared CoSn2 shows good electrochemical stability, and the overpotential for catalytic current densities of 1 and 10 mA cm(-2) remained stable during electrolysis for 110 h. The results indicate that the as-prepared CoSn2 shows oxygen evolution reaction activity comparable to P- and Se-containing cobalt-based benchmark catalysts and suggest that electrodeposited CoSn2 is an attractive noble-metal-free catalyst for water oxidation.