Surface Enrichment of Ir on IrRu Alloy for Efficient and Stable Water Oxidation Catalysis in Acid
Inducing surface enrichment of active noble metal can not only help to stabilize catalyst, but also modify the catalytic performance of catalyst through electronic and geometric effect. Herein we report in situ surface enrichment of Ir on IrRu alloy during the oxygen evolution reaction (OER). The surface enrichment of Ir was probed by ex situ high-resolution transmission electron microscopy (HRTEM), in situ X-ray absorption spectroscopy (XAS) and electrochemical Cu stripping, giving complementary characterizations on the dynamic reconstruction of IrRu alloy during OER. Guided by the density functional theory (DFT), an IrRu alloy with low Ir content (20 wt.%) was constructed, which displayed a low overpotential of only 230 mV to deliver an OER current density of 10 mA/cm2 in 0.1 M HClO4 solution and maintained stable performance for over 20 h. To investigate the practical application potential, a proton exchange membrane (PEM) water electrolyzer using the IrRu alloy as the anode catalyst was assembled, which required a low cell voltage of only 1.48 V to generate a current density of 1 A/cm2.