Abstract The development of active, stable, and cost‐effective electrocatalysts for the oxygen evolution reaction (OER) in acidic media is crucial for proton‐exchange‐membrane water electrolysis. Inspired by theoretical screening on a series of transition metal incorporated RuO 2 systems, a low Ru‐content solid solution oxide (Ru 0.48 Mn 0.52 O 2 ) achieved is fabricated by a simple two‐step synthesis method through the combination of rutile RuO 2 and β‐MnO 2 . The Ru 0.48 Mn 0.52 O 2 catalyst exhibits an exceptionally low overpotential of 154 mV at 10 mA cm −2 and maintains a high stability under a high current of 100 mA cm −2 for 50 h in 0.5 m H 2 SO 4 electrolyte. Furthermore, the obtained catalyst exhibits sustained stability at a large current of 0.5 A cm −2 for at least 50 h when loaded onto a Ti felt. The in‐situ characterization results indicate that Ru 0.48 Mn 0.52 O 2 preferably followed the adsorbate evolution mechanism rather than the lattice oxygen oxidation mechanism during the OER process, contributing to its high activity and stability at large current densities in acidic media.

Rutile‐Structured Ru0.48Mn0.52O2 Solid Solution for Highly Active and Stable Oxygen Evolution at Large Current Density in Acidic Media