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

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 RuO. Herein, we develop ultra-small BiRuO nanocrystal with diameter of approximately 6.5 ± 0.1 nm for acidic OER. The BiRuO nanocrystal electrocatalyst exhibits a low overpotential of 203.5 mV at 10 mA cm and 300+ hour stability at a high water-splitting current density of 100 mA cm in 0.5 M HSO with a low decay rate of 0.44 mV h. Density functional theory (DFT) calculation results confirmed the adsorbate evolving mechanism (AEM) occurring on BiRuO, 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.