Tuning amorphous Ir-IrOx oxygen evolution catalyst via precursor complexation for efficient and durable water electrolysis

Sluggish kinetics and corrosive condition of oxygen evolution reaction (OER) make it the bottleneck of proton exchange membrane water electrolyzer (PEMWE). It is essential to develop facile and scalable synthetic methods to elevate the activity and stability of OER electrocatalysts. We report a precursor complexation method to prepare a Ir-IrOx OER catalyst with crystalline Ir skeleton and amorphous IrOx surface. The appropriate valence states of amorphous IrOx surface and Ir skeleton were the probable origins of high activity and durability for OER by tuning the complexes and calcination temperature. An increasing calcination temperature and a complex with high decomposition rates led to more fractions of oxide surface as well as high valence state of Ir. The Ir-IrOx catalyst only required an overpotential of 228 mV to attain a current density of 10 mA cm-2, surpassing most reported Ir-based catalysts. A PEMWE equipped with the Ir-IrOx OER catalyst reached a current density of 1 A cm-2 at a low cell voltage of 1.67 V at 80 degrees C, and the applied voltage was almost unchanged in the 100 h' chronopotentiometry test, suggesting the potential practicability of the catalysts.