Optimizing Ru–Zn Dual Sites in Ru 1– x Zn x O ₂ for Efficient Acidic Water Oxidation via Oxide Path Mechanism

While Zn-doping significantly enhances the electrochemical performance of RuO₂ for the acidic oxygen evolution reaction (OER), the underlying mechanisms and the optimal design principles remain unclear. Here, we employ a cluster expansion (CE) model based on density functional theory (DFT) calculations to systematically explore energetically favorable configurations of Ru1-xZnxO₂ with Zn concentrations ranging from 4.2% to 25%. Our results reveal that varying Zn doping levels can both induce uniform Zn dispersion to create abundant atomically dispersed Ru-Zn dual-metal sites on the RuO₂(110) surface and enable precise tuning of Ru-Zn intersite distance to promote oxide path mechanism (OPM) in the OER. Moreover, the operating potential dynamically modulates the electronic structure of these dual-sites, adjusting adsorption energies of the OER intermediates and enabling precise control over reaction pathways. Additionally, the structural stability of Ru1-xZnxO₂ during the OER is positively correlated with the Zn-doping concentration and no longer significantly increased when the Zn concentration is >12.5%. Our findings establish two key design strategies for optimizing OPM: (1) maintaining low operating potentials and (2) controlling Zn doping at ∼12.5%. Under such conditions, OPM overcomes the theoretical limitations of conventional adsorbate evolution mechanism (AEM), achieving significantly reduced overpotentials and enhanced durability in acidic OER.