Intrinsic Descriptors Guide the Design of Stable Metal-Doped RuO2 Electrocatalysts for Acidic Oxygen Evolution

RuO2 is a benchmark anode catalyst for the acidic oxygen evolution reaction (OER) in proton-exchange membrane water electrolyzers (PEMWEs), but rapid dissolution severely limits its practical application. Although heteroatom doping can improve RuO2 durability, the intrinsic dopant properties governing individual dissolution steps remain poorly understood. Here, we combine density functional theory calculations (DFT) with surface Pourbaix analysis to investigate metal doped RuO2 (M-RuO2) under acidic OER conditions. The calculations reveal a cluster-like RuOxHy pathway governed by two key steps: Ru–O bond cleavage to form *RuO and subsequent hydroxylation to form *RuOOH. We identify the oxide formation energy (Eform) of the dopant oxide and dopant ionic electronegativity (χi) as intrinsic descriptors for these two steps, respectively. The former exhibits a volcano relationship with *RuO formation energy, whereas the latter shows an inverted-volcano relationship with *RuOOH formation energy. Together, these descriptors identify Mo, W, Ta, Nb, and Al as promising stabilizing dopants. Calculated OER activities for Ta, Nb, and Al-doped RuO2 further indicate that improved dissolution resistance can coexist with appreciable catalytic activity. For the dual-dopant systems examined, Ru–O bond cleavage is governed primarily by the stronger oxygen-binding dopant, whereas hydroxylation follows the average ionic electronegativity of the dopant pair. These findings link readily accessible dopant properties to elementary dissolution thermodynamics, providing a general strategy for screening and designing durable RuO2-based catalysts for acidic OER.