Boosting the acidic water oxidation activity by an interfacial oxygen migration in rutile-1 T-heterophase IrO2 catalysts

Iridium (Ir) - based electrocatalysts, as the benchmark electrocatalysts for oxygen evolution reaction (OER), still suffer from sluggish kinetics and substantial overpotential. Here we show the fabrication of heterophase IrO 2 catalysts with homogeneous distribution of rutile phase on 1 T phase (referred to as m-IrO 2 ) by a simple air-annealing method. In acidic condition, the m-IrO 2 catalyst exhibits high activity with a low overpotential of 170 mV at 10 mA cm −2 and good stability with no sign of deactivation over a prolonged 508-h continuous operation, making it one of the best-performing acid-stable OER catalysts. In this system, H 2 O first forms OH* and O* on the rutile phase, and then the interfacial oxygen migrates from the rutile phase to the 1 T phase. Subsequently, O* drives the OER reaction on the 1 T phase, resulting in the generation of OOH* and eventually the formation of O 2 . The interfacial oxygen migration within the heterophase structure of m-IrO 2 boosts the acidic water oxidation activity significantly. These findings provide a promising design strategy for creating high-activity catalysts suitable for acidic conditions through the manipulation of interfaces.