Uniformity, performance, and durability of roll-to-roll-coated iridium oxide electrolyzer catalyst layers

Abstract

This work investigates the use of roll-to-roll coating methods for the production of iridium oxide catalyst layers for proton exchange membrane water electrolyzers. Catalyst layers were produced using two coating methods: slot die and gravure. By varying the solids content of the catalyst ink and coating process variables loadings between 0.08 and 0.64 mg_Ir cm⁻² were prepared with relatively high spatial uniformity. However, at loadings below 0.2 mg_Ir cm⁻² microscopy reveals voids in the catalyst layer due to similar length scales of catalyst agglomerates and overall layer thickness. Electrochemical testing shows that these voids do not impact initial membrane electrode assembly performance but lead to increased performance losses after potential cycling compared to spray coated catalyst layers.