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

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 (Ru0.6Sn0.4O2) 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 Ru0.6Sn0.4O2 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.