Lewis Acid-Mediated Interfacial Water Supply for Sustainable Proton Exchange Membrane Water Electrolysis

The catalyst–electrolyte interface plays a crucial role in proton exchange membrane water electrolysis (PEMWE). However, optimizing the interfacial hydrogen bonding to enhance both catalytic activity and stability remains a significant challenge. Here, a novel catalyst design strategy is proposed based on the hard–soft acid–base principle, employing hard Lewis acids (LAs = ZrO₂, TiO₂, HfO₂) to mediate the reconfiguration of interfacial hydrogen bonding, thereby enhancing the acidic oxygen evolution reaction (OER) performance of RuO₂. Mechanistic analysis indicates that LAs prompt a directional evolution from a rigid hydrogen bonding network to free water, enhancing the trapping of interfacial water on the RuO₂ surface, which continuously supplies reactants to the catalytic sites. Moreover, the interconnected hydrogen bonding network facilitates rapid proton transfer, reducing local acidity on the catalyst surface and preventing structural corrosion, thus significantly improving long-term stability. The tandem pathway of water supply and deprotonation transforms the dissolution mechanism of traditional Ru-based catalysts, emphasizing the widespread applicability. Consequently, ZrO₂–RuO₂ displays a significantly reduced overpotential of 170 mV and exhibits high durability, sustaining 1800 h at 10 mA cm^–2 under acidic OER, and maintains robust activity for 100 h at 2 A cm^–2 in PEMWE, outperforming most Ru/Ir-based catalysts.