Modulating RuO2 Electrocatalysis via Introducing Lanthanides for Enhanced Acidic Oxygen Evolution

The low activity of ruthenium dioxide (RuO 2 ) and the rapid dissolution of the ruthenium (Ru) site during acid oxygen evolution reaction (OER) at high current density restricts its application in proton exchange membrane (PEM) electrolyzers. In this work, a series of rare-earth (RE) elements doped RuO 2 nanorods is developed as high-performance OER electrocatalysts. X-ray absorption spectroscopy suggests that RE doping regulates the local coordination environment around Ru sites, lowers the valance of Ru, and shortens the Ru─O─Ru(M) bond length, which enhances structural stability. Among the RE-RuO 2 samples, Sm-RuO 2 exhibits remarkable performance with a low overpotential of 283 mV to reach 100 mA cm −2 and maintained stability for over 140 h at 10 mA cm −2 . Moreover, the PEM electrolyzer using Sm-RuO 2 as the anode can be stably operated at 500 mA cm −2 for 15 h. Electrochemical analysis, X-ray photoelectron spectroscopy, and in situ Raman spectroscopy show that Sm doping lowers the d -band center, reduces the adsorption energy of O intermediates to enhance the OER activity, and restrains excessive oxidation of Ru sites while stabilizing lattice oxygen during the OER process, thereby enhancing OER stability. This work offers valuable insights into improving the stability of metal oxide catalysts in acidic electrolytes.