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, emerge as competitive candidates. However, the suboptimal stability constrains the widely application of RuO₂. Herein, we develop ultra-small Bi_0.05Ru_0.95O₂ nanocrystals with diameters 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+ hours stability under 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 reaction, thus avoids the collapse of 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.