Nanoporous IrO2 catalyst with enhanced activity and durability for water oxidation owing to its micro/mesoporous structure.

Herein, we report a nanoporous IrO2 catalyst with a surface area of 363.3 m2 g-1, the highest ever reported. The IrO2 catalysts were prepared by a facile ammonia-induced pore-forming method, and efficiently scaled up to several kilograms. Bimodal micro/mesopores were created at once without using a template. For the IrO2 (1 : 100)-450 °C (H2IrCl6 : NH3·H2O of 1 : 100) catalyst, the overpotential to attain a current density of 10 mA cm-2 for water oxidation was only 282 mV, and furthermore, its excellent durability was confirmed by accelerated durability tests. Moreover, the overall voltage to achieve a current density of 1000 mA cm-2 in a water electrolysis cell was only 1.649 V, making IrO2 (1 : 100)-450 °C a highly attractive catalyst for water electrolysis applications.