Shielding the Vulnerable: Enhanced Corrosion Resistance of Single-Atom Catalysts via Reaction-Driven Self-Protection Mechanism

Abstract

Single-atom catalysts can reduce platinum-group metal (PGM) use in proton exchange membrane (PEM) electrolyzers but are prone to aggregation and support corrosion. Here we demonstrate that anchoring Ru single atoms on acid-sensitive Mn3O4 effectively shields the Mn3O4 support from dissolution and prevents Ru migration. This dual protection stems from a feedback loop driven by rapid hydrogen evolution reaction (HER) kinetics. Ru atoms preferentially interact with oxygen-vacancy-rich sites in Mn3O4, contributing to defect passivation and forming robust Ru-O bonds that stabilize the isolated Ru sites. More importantly, ultrafast HER at Ru sites drive a continuous proton-pumping process, depleting interfacial protons and creating a localized less-acidic microenvironment, which reduces Mn3O4 corrosion. The resulting RuSA/Mn3O4 catalyst achieves exceptional acid HER performance with mass activity of 44.9 A mgRu-1 at -50 mV and stability exceeding 500 hours. In a PEM electrolyzer, it delivers current densities of 1 and 3 A cm-2 at low voltages of 1.65 and 1.87 V, respectively, and maintains 0.5 A cm-2 for over 220 hours with minimal degradation (26.7 µV h-1), using a total PGM loading of only 0.55 mg cm-2. This self-protection strategy expands viable supports and enables ultra-low-PGM catalysts for cost-effective green hydrogen production via PEM electrolysis.