High-entropy RuO2 catalyst with dual-site oxide path for durable acidic oxygen evolution reaction

Developing durable acidic oxygen evolution reaction catalysts is critical for industrial proton exchange membrane water electrolyzers. We incorporate high-entropy atoms (Co, Ni, Cu, Mn, Sm) into RuO2 (RuO2-HEAE) via annealing, achieving remarkably high stability (>1500 h at 100 mA cm−2). In situ differential electrochemical mass spectrometry and operando Attenuated Total Reflection Surface-Enhanced Infrared Absorption Spectroscopy reveal RuO2-HEAE follows a dual-site oxide path mechanism instead of the conventional adsorbate evolution mechanism. Quantitative Fourier-transformed extended X-ray absorption fine structure fitting and density functional theory calculations show this mechanistic shift stems from an elongated Ru-M distance in second coordination shell of RuO2-HEAE, enabling direct O-O coupling. This OPM-type catalyst delivers ~1500 h of stable operation at 1 A cm−2 and 50 °C, demonstrating superior durability versus most reported RuO2-based catalysts. This work provides fundamental insights for designing highly stable proton exchange membrane water electrolysis. Developing durable catalysts for the acidic oxygen evolution reaction is crucial for proton exchange membrane water electrolyzers. Here, the authors report incorporating high-entropy atoms (Co, Ni, Cu, Mn, Sm) into RuO2 via annealing, achieving stable operation at 1 A cm⁻² and 50 °C for 1500 h.