Rational design of atomic skin layers with low Ir–Ir atomic distance for highly efficient OER catalysts

The development of catalysts with highly efficient oxygen evolution performance and low-Ir loading is key to scaling up the application of proton exchange membrane (PEM) water electrolysis technology. Here, an Ir-skin catalyst (Ir@KM) is realized on a potassium-manganese oxide (K0.25MnOx (KM)) using an ion-exchange method. The Ir-skin over the prepared Ir@KM has a low Ir–Ir atomic distance, endowing an energetically favorable oxide path mechanism to allow a low theoretical overpotential of 0.13 V. Ir@KM offers a low overpotential of ~280 mV at a current density of 10 mA cm−2 and provides a high mass activity of up to 18,500 A at a cell voltage of 1.8 V in PEM, which is 17.6 times higher than that of IrO2, demonstrating a significant advantage in reducing the cost of the membrane electrode. The presented Ir-skin concept represents a promising strategy to fabricate low-Ir catalyst with high activity and durability for practical applications of PEM.