Enhanced Acidic Water Oxidation by Dynamic Migration of Oxygen Species at the Ir/Nb 2 O 5-x Catalyst/Support Interfaces.

Catalyst/support interaction plays a vital role in catalysis towards acidic oxygen evolution (OER), and the performance reinforcement is currently interpreted by either strain or electron donation effect. We herein report that these views are insufficient, where the dynamic evolution of the interface under potential bias must be considered. Taking Nb 2 O 5-x supported iridium (Ir/Nb 2 O 5-x ) as a model catalyst, we uncovered the dynamic migration of oxygen species between IrO x and Nb 2 O 5-x during OER. Direct spectroscopic evidence combined with theoretical computation suggests these migrations not only regulate the in situ Ir structure towards boosted activity, but also suppress its over-oxidation via spontaneously delivering excessive oxygen from IrO x to Nb 2 O 5-x . The optimized Ir/Nb 2 O 5-x thus demonstrated exceptional performance in scalable water electrolyzers, i.e., only need 1.839 V to attain 3 A cm -2 (surpassing the DOE 2025 target), and no activity decay during a 2000 h test at 2 A cm -2 .