IrPt Alloy Nanoparticles with Controllable Compositions as Catalysts for Electrochemical Oxygen and Hydrogen Evolution

When two metal precursors are reduced to form alloy nanoparticles (NPs), the final size usually varies by the composition because the reduction rate is different for each precursor. In this study, we report that the composition of IrPt alloy NPs can be easily controlled without affecting the size using an antisolvent crystallization-based method owing to the separation of the particle growth and precursor reduction steps. The synthesized IrPt alloy NPs displayed low overpotentials in both hydrogen evolution reaction (65 mV with a Tafel slope of 32.2 mV dec-1) and oxygen evolution reaction (240 mV with a Tafel slope of 77.9 mV dec-1) to deliver a current density of 10 mA cm-2 in H2SO4 (0.5 M), showing their enhanced electrocatalytic activities compared with the pure Pt and Ir catalysts.