Inhibiting Overoxidation of Dynamically Evolved RuO to Achieve a Win-Win in Activity-Stability for Acidic Water Electrolysis.

Proton exchange membrane (PEM) water electrolysis offers an efficient route to large-scale green hydrogen production, in which the RuO catalyst exhibits superior activity but limited stability. Unveiling the atomic-scale structural evolution during operando reaction conditions is critical but remains a grand challenge for enhancing the durability of the RuO catalyst in the acidic oxygen evolution reaction (a-OER). This study proposes an adaptive machine learning workflow to elucidate the potential-dependent state-to-state global evolution of the RuO(110) surface within a complex composition and configuration space, revealing the correlation between structural patterns and stability. We identify the active state with distorted RuO units that self-evolve at low potential, which exhibits minor Ru dissolution and an activity self-promotion phenomenon. However, this state exhibits a low potential resistance capacity (PRC) and evolves into inert RuO units at elevated potential. To enhance PRC and mitigate the overevolution of the active state, we explore the metal doping engineering and uncover an inverse volcano-type doping rule: the doped metal-oxygen bond strength should significantly differ from the Ru-O bond. This rule provides a theoretical framework for designing stable RuO-based catalysts and clarifies current discrepancies regarding the roles of different metals in stabilizing RuO. Applying this rule, we predict and confirm experimentally that Na can effectively stabilize RuO in its active state. The synthesized Na-RuO operates in a-OER for over 1800 h without any degradation and enables long-term durability in PEM electrolysis. This work enhances our understanding of the operando structural evolution of RuO and aids in designing durable catalysts for a-OER.