The Dopant Challenge: Site-Specific Control of Activity and Stability in RuO ₂ Oxygen Evolution Catalysts

The rational design of RuO2 catalysts for the acidic oxygen evolution reaction (OER) requires balancing intrinsic activity with long-term stability, yet the relationship between these properties remains poorly understood. Using density functional theory combined with the computational hydrogen electrode model, we systematically investigate how heteroatom doping (Ir, Ti, W) at specific Ru sites (cus and bridge) influences OER thermodynamics and surface corrosion on RuO2(110). Free-energy analysis identifies *OOH formation at coordinatively unsaturated Ru sites as the rate-determining step, while bridge oxygen atoms facilitate proton-coupled electron transfer. Structural, Bader charge, and crystal orbital Hamilton population (COHP) analyses reveal that site-specific dopant placement critically modulates Obr basicity, M–Obr covalency, and the electronic environment of reactive oxygens. Ti and Ir, when optimally positioned, enhance surface stability while maintaining or even improving intrinsic OER activity, demonstrating that the conventional activity–stability trade-off can be mitigated. In contrast, W primarily strengthens metal–oxygen bonds but offers limited stabilization and may hinder proton transfer. These findings establish mechanistic design principles for engineering RuO2-based catalysts in which dopant identity and precise placement govern whether activity and stability compete or can be optimized simultaneously, providing a pathway toward high-performance, durable acidic OER catalysts.