Bi-doped ruthenium oxide nanocrystal for water oxidation in acidic media

Abstract

There is an urgent need to develop a cost-effective and highly efficient acidic OER catalyst to support the progress of proton exchange membrane water electrolysis technology. Ruthenium-based catalysts, which possess high activity and significantly lower cost compared to iridium-based catalysts, emerge as competitive candidates. However, their suboptimal stability constrains the wide application of RuO₂. Herein, we develop ultra-small Bi_0.05Ru_0.95O₂ nanocrystal with diameter of approximately 6.5 ± 0.1 nm for acidic OER. The Bi_0.05Ru_0.95O₂ nanocrystal electrocatalyst exhibits a low overpotential of 203.5 mV at 10 mA cm⁻² and 300+ hour stability at a high water-splitting current density of 100 mA cm⁻² in 0.5 M H₂SO₄ with a low decay rate of 0.44 mV h⁻¹. Density functional theory (DFT) calculation results confirmed the adsorbate evolving mechanism (AEM) occurring on Bi_0.05Ru_0.95O₂, which prevents lattice oxygen from participating in the reaction, thus avoiding the collapse of the structure. We proved that the Bi dopants could play a crucial role in not only reducing the energy barrier of the potential-determining step, but also delivering electrons to Ru sites, thereby alleviating the over-oxidation of Ru active sites and enhancing operation durability.