Boosting the Stability of RuO₂ in the Acidic Oxygen Evolution Reaction by Tuning Oxygen‐Vacancy Formation Energies: A Viable Approach Beyond Noble‐Metal Catalysts?

RuO 2 belongs to the most active electrode materials for the anodic oxygen evolution reaction (OER) within the electrochemical water splitting, such as those encountered in acidic proton‐exchange membrane (PEM) electrolyzers. Despite its large activity, RuO 2 faces severe stability issues under the harsh anodic operation conditions. Now, a new strategy has been reported to overcome this bottleneck by tuning the free‐formation energy of oxygen vacancies, which can be achieved by the co‐doping of W and Er into the RuO 2 lattice. The resulting W 0.2 Er 0.1 Ru 0.7 O 2‐δ electrocatalyst is stable long term in acid and, additionally, reveals remarkable OER activity, about 30 times higher than that of commercial RuO 2 . The notion of tuning the oxygen‐vacancy formation energy could be a valuable starting point for the development of non‐noble electrocatalysts for the acidic OER with applications in PEM electrolyzers.