Ionomer Dispersion for IrO2 Based Oxygen Evolution Reaction Electrode with for Decal Process Application

Abstract

Green hydrogen production is of importance in the upcoming hydrogen economy era. Proton exchange membrane (PEM) water electrolysis is one of the most important technology to produce the green hydrogen, which requires only water and extra electricity supplied from renewable energy. Main component, i.e., membrane electrode assembly (MEA), is a key part consisting of polymer electrolyte membrane and two electrodes which are oxygen evolution reaction (OER) electrode and hydrogen evolution (HER) electrode. Both electrode should be coated on the surface of membranes for better performance and mass production. HER could be coated by spraying or decal processes since Pt/C electrocatalysts allow to be dispersed in diluted (for spraying) and concentrated (for decal) catalyst inks. However, OER electrode mainly uses IrO2 black electrocatalyst which only allows diluted catalyst inks due to low surface area of IrO2. Thus, OER is generally coated by a spray method. For a decal process for OER electrode, high concentration or high viscosity of catalyst ink should be prepared. In this study, high viscosity ionomer dispersions were prepared using commercially available ionomer dispersions in water and alcohol mixture by substituting water and alcohol solvents into high viscosity solvent (propylene glycol in this study). High viscosity solvent-based ionomer dispersion was investigated for high concentration or high viscosity catalyst ink. The OER electrodes using high viscosity ionomer dispersions were evaluated by electrochemical characterization such as I-V polarization and activation rate. Acknowledgment This research was supported in part by the Hydrogen Energy Innovation Technology Development Program of the National Research Foundation (NRF) funded by the Ministry of Science, ICT ＆ Future Planning (NRF-2019M3E6A1063677) and by 2021 Green Convergence Professional Manpower Training Program of the Korea Environmental Industry and Technology Institute funded by the Ministry of Environment.