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

Abstract

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.