Hollow IrCo Nanoparticles for High-Performance Overall Water Splitting in an Acidic Medium

Producing high-purity hydrogen (H2) via highly efficient electrolytic water splitting remains a highly desired technique, which still holds considerable challenges. In this study, monodispersed IrCo hollow nanoparticles (HNPs) were prepared through a one-pot process, which affords excellent bifunctional electrocatalytic performance toward overall water splitting in an acidic medium. Alloying Ir with 3d transition metals (M) proved to be a key component in increasing oxygen evolution reaction (OER) activity by reducing the adsorption energy of oxygen intermediates on IrM. The overpotentials for OER and hydrogen evolution reaction (HER) of 281 and 23 mV at a current density of 10 mA cm–2, respectively, exceed the capabilities of commercial IrO2 and Pt/C catalysts. This phenomenon can be credited to the alloying effect and the unique hollow structure of IrCo HNPs as well as the strong electron interactions brought about by Ir–Co atomic-level synergistic alloying effects. An overall water splitting current density of 10 mA cm–2 can be achieved at a low cell voltage of 1.52 V, demonstrating an innovative way for efficient high-purity hydrogen generation in an acidic medium.