Rutile‐Structured Ru_0.48Mn_0.52O₂ Solid Solution for Highly Active and Stable Oxygen Evolution at Large Current Density in Acidic Media

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 RuO2 systems, a low Ru‐content solid solution oxide (Ru0.48Mn0.52O2) achieved is fabricated by a simple two‐step synthesis method through the combination of rutile RuO2 and β‐MnO2. The Ru0.48Mn0.52O2 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 H2SO4 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 Ru0.48Mn0.52O2 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.