Intermetallic IrGa-IrO x core-shell electrocatalysts for oxygen evolution

The development of high-performance Ir-based catalyst for electrocatalysis of oxygen evolution reaction (OER) in acidic media plays a critical role in realizing the commercialization of polymer electrolyte membrane-based water electrolyzer technology. Here we report a low-Ir core-shell OER electrocatalyst consisting of an intermetallic IrGa (IrGa-IMC) core and a partially oxidized Ir (IrO x ) shell. In acidic electrolytes, the IrGa-IMC@IrO x core-shell catalysts exhibit a low overpotential of 272 mV at 10 mA·cm −2 with Ir loading of ∼20 µg·cm −2 and a mass activity of 841 A·g Ir −1 at 1.52 V, which is 3.6 times greater than that of commercial Ir/C (232 A·g Ir −1 ) catalyst. We understand by the density functional theory (DFT) calculations that the enhanced OER activity of the IrGa-IMC@IrO x catalysts is ascribed to the lifted degeneracy of Ir 5d electron of surface IrO x sites induced by the intermetallic IrGa core, which increases the adsorption capacity of IrO x layer for O and OH binding and eventually lowers the energy barrier of the OER rate-determining steps.