Surface Hydroxylated Mn-Doped RuO₂ as an Efficient and Stable Electrocatalyst for Acidic Oxygen Evolution Reaction

The role of surface hydroxylation in the performance of RuO2-based electrocatalysts for oxygen evolution reaction (OER) is crucial but still unclear. Using first-principles calculations, we comprehensively studied the impact of surface hydroxylation states on the activity and stability of Mn-doped RuO2-based electrocatalysts (denoted as nOH-Mn0.1Ru0.9O2, n = 1–5) in acidic OER. It was revealed that the moderately hydroxylated Mn0.1Ru0.9O2 demonstrates better performance than the fully hydroxylated structure, and 4OH-Mn0.1Ru0.9O2 holds the lowest reaction barrier of 0.14 eV in solvation under the constant potential of 1.5 V, which is lower than those of both pure RuO2 (0.28 eV) and Mn0.1Ru0.9O2 (0.23 eV). Such an increase in catalytic activity stems from the nonstrong-and-nonweak charge transfer of reaction sites. In addition, the synergistic effect of doping and hydroxylation can also increase the stability of RuO2 through inhibition of structure collapse caused by the dissolution of Ru and the loss of lattice oxygen. The present study has provided a novel strategy for the design of efficient and stable RuO2-based acidic OER catalysts through surface hydroxylation.