Dynamically-evolved surface heterojunction in iridium nanocrystals boosting acidic oxygen evolution and overall water splitting

Simultaneously realizing improved activity and stability of acidic oxygen evolution reaction (OER) electrocatalysts is highly promising for developing cost-effective sustainable energy in the splitting of water technique. Herein, we report iridium nanocrystals embedded into 3D conductive clothes (Ir-NCT/CC) as a low iridium electrocatalyst realizing ultrahigh acidic OER activity and robust stability. The well-designed Ir-NCT/CC requires a low overpotential of 202 mV to reach the current density of 10 mA cm−2 with a high mass activity of 1754 A g−1. Importantly, in acidic overall water splitting, Ir-NCT/CC merely delivers a cell voltage of 1.469 V at a typical current density of 10 mA cm−2 and also maintains robust durability under continuous operation. We identify that a low working voltage drives the formation of a highly stable amorphous IrOx active phase over the surface of Ir nanocrystals (surface heterojunction IrOx/Ir-NCT) during operating conditions, which contributes to an effective and durable OER process.