Lead-doped ruthenium-iridium oxide catalysts for durable acidic oxygen evolution in proton exchange membrane electrolyzers at 3 A/cm2

Abstract Widespread deployment of proton exchange membrane water electrolyzers (PEMWE) relies on acidstable oxygen evolution reaction (OER) catalysts capable of operating at high current densities.Inspired by the robust chemistry of lead-acid batteries, we introduce lead (Pb) into ruthenium-iridium mixed oxide (RuIrO x ) through a facile sol-gel method. The as-prepared RuIrPbO x nanoparticulate catalysts with the optimal composition (Ru 0.5 Ir 0.4 Pb 0.1 O x ) achieve an overpotential of 241 mV at 10 mA cm -2 and exceptional stability of 1000 hours at a high current density of 100 mA cm -2 without degradation. In-situ differential electrochemical mass spectrometry (DEMS) indicates that doping RuIrO x with an appropriate amount of Pb helps to suppress the participation of lattice oxygen during OER, contributing to structural preservation and long-term stability. Density functional theory (DFT) calculations reveal that Pb doping effectively modulates the electronic structure of Ru sites, reducing Ru-O covalency, which in turn increases Ru dissolution energy and therefore prevents Ru leachinga key degradation pathway for Ru-containing OER catalysts. When integrated into a membrane electrode assembly (MEA), the PEMWE cell can operate at a large current density of 3.0 A cm -2 under 1.96 V (@60°C) for 400 hours with minimal performance degradation, demonstrating significant potential of the Ru 0.5 Ir 0.4 Pb 0.1 O x as an efficient and durable OER catalyst for practical applications under demanding conditions.