Synergistic oxyanion engineering on RuO2 enables highly active and stable acidic water oxidation

Developing highly active and stable acidic oxygen evolution reaction (OER) catalysts for proton exchange membrane water electrolysis (PEMWE)is critical for green hydrogen production. While conventional RuO 2 -based catalysts exhibit superior intrinsic activity, their practical application is severely hampered by an activity-stability trade-off. Herein, we propose an oxyanion engineering strategy that successfully overcomes this bottleneck by achieving surface hydroxylation and introducing sacrificial agents in RuO 2 . On one hand, the strategy-induced surface hydroxyls (-OH) significantly accelerate the reaction kinetics, delivering a low overpotential of 189 mV at 10 mA cm −2 . On the other hand, inductively coupled plasma mass spectrometry (ICP-MS) results reveal that in-situ introduced WO x acts as a sacrificial agent, effectively mitigating over-oxidation and dissolution of Ru. In-situ electrochemical impedance spectroscopy and differential electrochemical mass spectrometry (DEMS) confirm that the catalyst follows an optimized adsorbate evolution mechanism (AEM) pathway with suppressed lattice oxygen participation, ensuring long-term stability (>220 h at 10 mA cm −2 ). Ultimately, when applied in PEMWE, the catalyst enables a low cell voltage of 1.79 V at 1 A cm −2 and maintained stable operation for 100 h at 200 mA cm −2 . This work establishes a new paradigm of dual-functional synergistic design for developing efficient and durable acidic OER catalysts.