ALD-Based IrOx/Ir Supported Electrocatalysts for Water Electrolysis Technology

Abstract

Hydrogen (H2) is an alternative energy vector to replace fossil fuels, with potential applications like hydrogen fuel cell-powered vehicles and in the chemical industry. H2 production through polymer electrolyte membrane (PEM) water electrolysis (WE) appears to be a highly promising technology. While iridium oxide is the most commonly used anode oxygen evolution reaction (OER) catalyst for PEMWE, its scarcity makes it an extremely critical raw material. In order to obtain active and stable anodes with an ultra-low iridium loading, we are developing a strategy based on doped metal oxides as conductive supports, on which iridium-based thin films and/or nanostructures are deposited using atomic layer deposition (ALD). ALD can indeed allow the control of the amount of deposited species at sub-nanometric scale by changing the number of ALD cycles, thus ensuring a minimal iridium loading for efficient OER catalysis. In this study, the influence of the temperature of deposition was investigated to obtain either IrOx ultrathin films or Ir nanoparticles. The morphology and composition of these deposits were characterized by scanning and transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The nature and crystallinity of these electrocatalysts will indeed have a huge impact on their catalytic activity and the subsequent electrode’s efficiency as well as in their long-term durability. In brief, we will present the production of nano-structured OER electrocatalysts, in which the bulk consists of a sufficiently conductive metal oxide support with the surface uniformly coated with an ultra-low loading of iridium deposited via conformal ALD.