Tantalum-stabilized ruthenium oxide electrocatalysts for industrial water electrolysis

The iridium oxide (IrO₂) catalyst for the oxygen evolution reaction used industrially (in proton exchange membrane water electrolyzers) is scarce and costly. Although ruthenium oxide (RuO₂) is a promising alternative, its poor stability has hindered practical application. We used well-defined extended surface models to identify that RuO₂ undergoes structure-dependent corrosion that causes Ru dissolution. Tantalum (Ta) doping effectively stabilized RuO₂ against such corrosion and enhanced the intrinsic activity of RuO₂. In an industrial demonstration, Ta-RuO₂ electrocatalyst exhibited stability near that of IrO₂ and had a performance decay rate of ~14 microvolts per hour in a 2800-hour test. At current densities of 1 ampere per square centimeter, it had an overpotential 330 millivolts less than that of IrO₂.