Eliminating over-oxidation of ruthenium oxides by niobium for highly stable electrocatalytic oxygen evolution in acidic media

Proton exchange membrane (PEM) water electrolysis shows advantages including high current density, high efficiency, and compact configuration but suffers from the scarcity and high price of iridium (Ir)-based anodic catalysts. Herein, insoluble niobium (Nb)-incorporated RuO 2 with a high valence state was designed as an Ir-free catalyst for active and stable acidic oxygen evolution reaction (OER). Nb 0.1 Ru 0.9 O 2 exhibited a low overpotential (204 mV) and superb stability with an ultralow degradation rate (25 μV/h) over a 360-h durability test at 200 mA cm −2 , which is only 1/100th of the decay rates of other Ru-based catalysts measured at 10 mA cm −2 . The PEM electrolyzer with Nb 0.1 Ru 0.9 O 2 as an anode survived from a 100-h operation at 300 mA cm −2 . The strengthened adsorption of oxygen intermediates to active Ru sites reduced the OER energy barrier, while the enhanced electron transfer to Ru by Nb doping and formation of Nb 5+ during the OER process extended catalyst’s durability.