Suppressive Ru oxidation and activated lattice oxygen in Mn doped RuO2 for efficient acidic oxygen evolution reaction

The inevitable electrochemical oxidation accompanied with continuous dissolution of Ru triggers structural distortion, causing insufficient catalytic activity and stability of Ru-based electrocatalysts in acidic oxygen evolution reaction (OER). In this work, we propose a Mn doping strategy to obtain Mn doped RuO 2 (Mn-RuO 2 ) for stabilizing the dynamic Ru. X-ray absorption spectroscopy and X-ray photoelectron spectroscopy results indicate that the doped Mn in RuO 2 preferentially replaces the oxidation of Ru by self-oxidation during the OER process, which significantly suppresses excessive dissolution of Ru. Furthermore, in-situ Raman spectroscopy, in-situ electrochemical impedance spectroscopy, the differential electrochemical mass spectrometry measurements combined with density functional theory calculations demonstrate that the Mn doping is able to strengthen the covalency of metal–oxygen bonds, facilitate lattice oxygen mechanism with elevated energy level of O 2p band. Therefore, Mn-RuO 2 catalyst demonstrates remarkable acidic OER performance, only needing an overpotential of 209 mV to achieve the current density of 10 mA cm –2 , 139 mV lower than that of commercial RuO 2 . And Mn-RuO 2 can maintain stable operation for over 180 h, which is about 18 times that of commercial RuO 2 . Notably, when Mn-RuO 2 is used as the anode, the proton exchange membrane water electrolyzers demonstrates stable operation for 40 h at 100 mA cm −2 . This work offers a strategy to alleviate stability issue of Ru-based catalysts for efficient acidic OER process.