Polymer-mediated Exsolution and Segregation of Ruthenium Oxides on β-MnO2 for Durable Water Oxidation in Proton-Exchange Membrane Electrolyzer

Abstract

The development of acid-stable and low-noble-metal electrocatalysts for oxygen evolution reaction (OER) is challenging but demanding for large-scale application of proton-exchange membrane water electrolyzers (PEMWE). Herein, taking advantage of the densely packed and stable crystalline structure of β-MnO2 and the dopant-induced lattice strain, a high-performance OER catalyst with low Ru loading is developed via the thermally-driven and polymer-mediated exsolution and segregation process. While high-resolution microscopic studies clearly illustrate the Schottky mechanism involved in the formation of polycrystalline RuOx-containing grains anchored to the MnO2 support, spectroscopic evidences unveil a significantly altered electronic structure with reduced Mn and Ru chemical states, as well as populated vacancies. Consequently, the best catalyst of Ru-MnO2-PT achieves a remarkable OER activity in acidic medium, requiring an overpotential of only 163 mV to reach the current density of 10 mA cm−2, in addition to a superb electrolytic stability, enabling a prolonged operation of PEMWE for over 2000 hours. This study sheds new light on controllably regulating the exsolution and segregation process of noble metal-doped transition metal oxides for the fabrication of highly robust OER catalysts.