Synergistic Effect of Mn and V in Regulating Low-Ruthenium Oxide Nanowires for Highly Efficient and Stable Acidic Water Oxidation

Abstract

Suppressing the dissolution of Ru sites in Ru-based oxides during the oxygen evolution reaction (OER) in acidic media is a critical challenge for the development of low-cost proton exchange membrane water electrolysis (PEMWE) technology. In this study, Ru 0.2 V 0.05 Mn 0.75 O 2 nanowires were synthesized via a hydrothermal method. Through the synergistic effect of Mn and V, the crystal structure and the bond energy of the Ru–O bonds in the Ru-based oxide were effectively modulated. The Ru 0.2 V 0.05 Mn 0.75 O 2 catalyst exhibited OER overpotentials of 212 and 295 mV at 10 and 50 mA cm − 2 respectively in 0.5 M H 2 SO 4 , values 132 and 148 mV lower than those of pure RuO 2 . When employed as an anode in a PEMWE cell, Ru 0.2 V 0.05 Mn 0.75 O 2 achieved a cell voltage of only 1.61 V at a current density of 1 A cm⁻² and demonstrated stable operation for over 250 hours. Electrochemical impedance spectroscopy (EIS) analysis revealed that the incorporation of Mn and V helps reduce charge-transfer resistance during the OER. Furthermore, inductively coupled plasma optical emission spectroscopy (ICP-OES) and density functional theory (DFT) calculations indicate that the synergistic effect of Mn and V increases the vacancy formation energy of Ru sites—from 1.68 eV in RuO 2 to 2.75 eV in Ru 0.2 V 0.05 Mn 0.75 O 2 —thereby effectively suppressing the dissolution of Ru sites during the OER process and enhancing the structural stability of the material.

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