Lewis base-mediated stabilization of the lattice oxygen mechanism in RuO₂ for robust acidic water oxidation

Stabilizing the lattice oxygen oxidation mechanism (LOM) pathway of Ru-based oxygen evolution reaction (OER) electrocatalysts under acidic conditions is pivotal for efficient proton exchange membrane (PEM) water electrolysis. Herein, we propose a Lewis base regulation strategy by introducing In into RuO₂ to activate and stabilize the LOM process during the OER. Integrated in situ and ex situ characterization studies and theoretical calculations reveal that the In acts as an electron donor to modulate the interfacial water structure and accelerate deprotonation, thereby ensuring a continuous supply of *OH. Furthermore, In doping optimizes the electronic structure to promote *OH adsorption on Ru sites, enhance the Ru-O covalency, and stabilize oxygen vacancies generated during the LOM process, thereby synergistically improving both the activity and stability of the Ru-based catalyst along the LOM pathway. Benefiting from this Lewis base modulation, In-RuO₂ exhibits outstanding acidic OER performance, achieving 10 mA cm^-2 at an overpotential of only 194 mV with excellent stability (>1000 h). Furthermore, In-RuO₂ outperforms RuO₂ in PEM electrolyzer tests, operating stably for over 1000 h at 1 A cm^-2. This work offers a design principle for highly active and stable LOM catalysts toward scalable green hydrogen production.