Competitive adsorption of oxygen-containing intermediates on ruthenium–tin solid-solution oxides for alkaline oxygen evolution

Abstract

Ruthenium dioxide (RuO₂) has been considered a benchmark electrocatalyst for the oxygen evolution reaction, according to the volcano theory. However, the comparatively strong adsorption of RuO₂ and oxygenated intermediates restricts its performance during the actual oxygen evolution reaction (OER) process. Here, we have developed a rutile-structured ruthenium–tin solid-solution oxide (Ru_0.6Sn_0.4O₂) by using a competitive adsorption strategy to accelerate the OER kinetics. Sn was introduced into RuO₂ to construct a solid-solution oxide structure, given the similar ionic radii, identical cation valence, and the same crystal structure for the oxides. As a consequence, the Ru_0.6Sn_0.4O₂ catalyst displayed a low overpotential of 245 mV, reaching 10 mA cm⁻² current density and a low Tafel slope of 61.80 mV dec⁻¹ in 1.0 M KOH electrolyte. Meanwhile, theoretical calculations revealed that the incorporation of Sn components decreased the anti-bonding spin states of the Ru d orbitals, which modulated the energy barrier of the rate-determining step, thus accelerating the OER kinetics. This approach extends the ideas for designing efficient solid-solution oxide electrocatalysts.