Ru/RuO₂ Heterostructures for Stable and Active Acidic Water Oxidation via Interfacial Charge Redistribution and...

The rational design and synthesis of Ir-free acidic oxygen evolution catalysts combining high activity with long-term durability remains a formidable challenge. This work demonstrates an addressable and dopant-free strategy through the construction of Ru/RuO₂ heterostructures in a solely Ru-based system, wherein interfacial charge redistribution and lattice-oxygen participation jointly promote catalytic enhancement. The catalyst delivers an overpotential of 182 mV at 10 mA·cm^-2 and retains operational durability for over 270 h at 100 mA·cm^-2 in 0.5 M H₂SO₄. Spectroscopic characterizations, including X-ray absorption spectroscopy (XAS), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS), coupled with theoretical calculations, elucidate that interfacial electron transfer from metallic-Ru phase to RuO₂ phase, assisted by the formation of a built-in electric field, results in increased work functions across the heterointerface and lowered interfacial Ru oxidation states, suppressing Ru-site overoxidation into soluble RuO₄ and accounting for the exceptional durability. Lattice-oxygen participation, which corresponds to excellent activity, was verified by operando investigations, including differential electrochemical mass spectrometry (DEMS), attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS), and tetramethylammonium (TMA⁺) chemical probing. The overall findings establish heterointerface engineering as a powerful tool for the simultaneous enhancement of the coupled activity-stability in Ru-based acidic OER catalysts.