Iridium Stabilizes\nCeramic Titanium Oxynitride Support\nfor Oxygen Evolution Reaction

Abstract

Decreasing iridium loading in the electrocatalyst presents\na crucial\nchallenge in the implementation of proton exchange membrane (PEM)\nelectrolyzers. In this respect, fine dispersion of Ir on electrically\nconductive ceramic supports is a promising strategy. However, the\nsupporting material needs to meet the demanding requirements such\nas structural stability and electrical conductivity under harsh oxygen\nevolution reaction (OER) conditions. Herein, nanotubular titanium\noxynitride (TiON) is studied as a support for iridium nanoparticles.\nAtomically resolved structural and compositional transformations of\nTiON during OER were followed using a task-specific advanced characterization\nplatform. This combined the electrochemical treatment under floating\nelectrode configuration and identical location transmission electron\nmicroscopy (IL-TEM) analysis of an in-house-prepared Ir-TiON TEM grid.\nExhaustive characterization, supported by density functional theory\n(DFT) calculations, demonstrates and confirms that both the Ir nanoparticles\nand single atoms induce a stabilizing effect on the ceramic support\nvia marked suppression of the oxidation tendency of TiON under OER\nconditions.