N/C doped nano-size IrO2 catalyst of high activity and stability in proton exchange membrane water electrolysis.

It is highly desirable to synthesize and deploy low-cost and highly efficient catalysts for the oxygen evolution reaction (OER) to catalyze water splitting. We show that N/C doped amorphous iridium oxide combines the benefits of nano-size (approximately 2 nm), which results in exposure to large active surface areas and features of oxygen defects, which make for an electronic structure suitable for the OER. Systematic studies indicate that the OER activity of the iridium oxide catalyst is accelerated by the effect of the structure and chemical state of the iridium element. Remarkably, the N/C doped amorphous iridium oxide catalyst shows a lower cell voltage of 1.774 V at 1.5 A cm−2, compared with IrO 2 (1.847 V at 1.5 A cm−2), and it can maintain such a high current density for over 200 h without noticeable performance deterioration. This work provides a promising method for the improving OER electrocatalysts and the construction of an efficient and stable PEM water cracking system. • Carbon nitride was used as additive and dopant to synthesize N/C doped amorphous iridium oxide. • N/C doped amorphous iridium oxide with large surface area and an oxygen-defective feature. • N/C doped amorphous iridium oxide exhibits superior electrochemical activity and higher ECSA than pure iridium oxide. • Electrolyzer achieved 1.774 V@1.5Acm−2 of PEMWE excellent durability over 200 h. [ABSTRACT FROM AUTHOR]