Intermetallic IrGa-IrOx 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 (IrOx) shell. In acidic electrolytes, the IrGa-IMC@IrOx 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·gIr−1 at 1.52 V, which is 3.6 times greater than that of commercial Ir/C (232 A·gIr−1) catalyst. We understand by the density functional theory (DFT) calculations that the enhanced OER activity of the IrGa-IMC@IrOx catalysts is ascribed to the lifted degeneracy of Ir 5d electron of surface IrOx sites induced by the intermetallic IrGa core, which increases the adsorption capacity of IrOx layer for O and OH binding and eventually lowers the energy barrier of the OER rate-determining steps.