The acidic OER activation-decay process of highly active Ir-Ni mixed oxide modified by capping agent for both particle fining and Ir-OH formation

Developing highly active catalyst for oxygen evolution reaction (OER) with low noble metal loading is crucial for the application of proton exchange membrane (PEM) water electrol-ysis. Ir-transition metal (TM) binary catalyst with chemical leaching was reported to perform excellent activity with TM leaching. However, most of the studies on the activation-decay focused on the final status, and the variation process remains unclear. With cysteamine center dot HCl, a modified facile molten salt method was applied to prepared highly active Ir-Ni mixed oxide (c-xNiIrMO), which perform 5.5 times higher mass activity than commercial IrO2. The variation of active surface area, intrinsic activity, conductivity of prepared catalyst layer during the activation process are studied to unveil the key factors for the activity enhancement. With further stability test, c-xNiIrMO with Ni content lower than 67% performs decrease intrinsic activity and improved kinetic performance in the first hundred cycles. After obtaining a stable Ir0.95Ni0.05Ox structure, further cycling results in typical activity decay with dissolution of Ir.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.