Sonochemical boron incorporation enhances activity and durability of ruthenium oxide for acidic water oxidation

The inherent instability of ruthenium oxide in acidic environments, coupled with the persistent activity-stability trade-off, constitutes a fundamental barrier to advancement of proton exchange membrane water electrolyzers. Here we show a cavitation-mediated sonochemical strategy that enables homogeneous substitutional boron doping of ruthenium oxide within minutes under ambient conditions. By substituting lattice ruthenium sites and forming strong covalent boron-oxygen bonds, boron doping enhances the intrinsic activity and stability by optimizing oxygen-intermediate adsorption and suppressing lattice oxygen participation, thereby mitigating catalyst degradation. The resulting boron-doped ruthenium oxide exhibits a low overpotential of 180 mV at 10 mA cm−2 with long-term durability (>3000 h). In proton exchange membrane water electrolyzers, this catalyst achieves industrial current densities (1 A cm−2 at 1.714 V) for over 200 h with a negligible voltage degradation rate of 65.0 μV h−1. This work demonstrates the potential of cavitation-mediated sonochemistry for synthesizing efficient catalysts with enhanced stability and provides insights into the design of doped oxide materials. Ruthenium oxide is active for acidic water electrolysis but degrades under operating conditions. Here, the authors report a cavitation-mediated sonochemical strategy to incorporate boron into Ruthenium oxide, improving its activity and durability for water electrolysis.