Synthesis of Cu–Ir nanocages with enhanced electrocatalytic activity for the oxygen evolution reaction

Abstract

Iridium (Ir) is widely used as a catalyst in polymer electrolyte membrane water electrolyzers (PEMWEs). However, high cost and limited catalytic performance of Ir hamper its large-scale industrial application. Here, based on a modified galvanic replacement, we introduce Cu nanoparticles as a template to prepare single-crystalline Cu–Ir polyhedral nanocages (NCs). Alloying Ir with 3d transition metal Cu not only significantly reduces the loading of Ir but also remarkably enhances its catalytic activity by forming a unique NC structure and tuning the d-band structure of Ir. The as-prepared single-crystalline Cu_1.11Ir NCs exhibit enhanced catalytic activity toward the oxygen evolution reaction (OER) in 0.05 M H₂SO₄, with a smaller overpotential (286 mV) required for a current density of 10 mA cm⁻² and a Tafel slope of 43.8 mV per decade. The mass activity can reach 73 mA mg_Ir⁻¹ at an overpotential of 0.28 V for Cu_1.11Ir NCs. Hence, the obtained Cu_1.11Ir NCs would be a promising electrocatalyst for practical electrocatalytic water splitting systems.