PNNL

Abstract

Proton exchange membrane (PEM) water electrolysis offers key advantages, including high current density, high efficiency, and compact system architecture for hydrogen production. However, its widespread implementation is limited by the scarcity and high cost of Ir-based anodic catalysts. Herein, we report an Ir-free electrocatalyst for the acidic oxygen evolution reaction (OER): tantalum oxide (TaOx)–coated molybdenum-doped RuO2 (TaOx-MoRuO2). The catalyst exhibits a low overpotential of 180 mV at 10 mA cm-2 and excellent durability, with a degradation rate of 0.034 mV h-1 over a 150-hour test at 50 mA cm-2—surpassing other Ru-based catalysts evaluated under similar conditions. A PEM electrolyzer employing TaOx-MoRuO2 as the anode maintained stable operation for 100 hours at 500 mA cm-2. The TaOx coating layer suppresses Ru and Mo dissolution, thus enhancing their stability likely via interfacial electronic reconfiguration of Ru and Mo mediated by bridging oxygen atoms.