The role of Pt-black in achieving ultra-low iridium loadings for proton exchange membrane electrolyzers

Abstract

Proton exchange membrane water electrolyzers (PEMWEs) are a promising technology for generating clean hydrogen. However, their reliance on high contents of costly iridium (Ir) presents a significant economic barrier. Reducing loadings from conventional values of ∼1–2 mg_Ir cm⁻² to <0.3 mg_Ir cm⁻² has been highly challenging due to a loss of continuity in the anode layer at such low loadings. This study explores the addition of platinum (Pt) to the anode layer to improve electronic connectivity. We conduct a detailed investigation into the required Pt loadings to ensure sufficient electronic pathways. While previous work indicated a loading of 1 mg_Pt cm⁻² is necessary to overcome low Ir loading limitations, it is shown here that for a 0.1 mg_Ir cm⁻² anode layer, a loading of only 0.3 mg_Pt cm⁻² can enable a full electronic connection within the anode layer, with higher loadings having no additional kinetic/conductivity benefit and in fact resulting in larger mass transfer (MT) losses. Finally, we provide a brief cost analysis to determine under which scenarios this strategy is economically viable.