TiNxOy/TiN Supported Ir-Oxide/Ir As Efficient OER Electrocatalyst for Acidic Water Electrolysis

Abstract

Increasing the mass activity of Iridium-based electrocatalysts for oxygen evolution reaction (OER) is of significant importance for sustainable acidic water electrolyzers generating green hydrogen. Here, we have studied surface oxidized TiN (TiNxOy/TiN) as a catalyst support for Ir-based OER electrocatalysts with high mass activity. TiNxOy/TiN supported Ir-oxide/Ir nanoparticles were synthesized using a microwave-assisted approach. The synthesized IrO2@Ir/TiN with an Ir loading of 40 wt% exhibits a mass-normalized OER activity of ~2.4 times that of a commercial benchmark IrO2 OER electrocatalyst. The synthesized TiNxOy/TiN supported Ir-oxide/Ir catalyst, owing to superior utilization of the active catalyst surface and improved intrinsic activity through catalyst-support interaction, enables significant (~60 wt.%) reduction in the Ir metal loading required to obtain equivalent OER performance, compared to commercial benchmark. In addition, accelerated stress test (AST) involving potential cycling in acidic media suggest the IrO2@Ir/TiN catalyst to be of relatively higher durability (activity retention: 79%) compared to that of the commercial equivalent (activity retention: 66%). In the presentation, we discuss the findings focusing on impacts of surface chemistry of the synthesized catalysts on their mass-activity and the degradation mechanisms during AST. The study opens a new perspective for further research towards development of low-Ir loading OER electrocatalysts. Reference Karade, S. S.; Sharma, R.; Gyergyek, S.; Morgen, P.; Andersen, S. M., ChemCatChem 2023, e202201470, DOI: https://doi.org/10.1002/cctc.202201470.