Design of PEM water electrolysers with low iridium loading

Abstract

To enable gigawatt-scale deployment of proton exchange membrane water electrolysers (PEMWEs), drastic reductions from current iridium loadings of 2–3 mgIr cm−2 to less than 0.4 mgIr cm−2 must occur due to iridium's high cost and scarcity. State-of-the-art systems use these high loadings to compensate for degradation experienced over prolonged operation. Thus, to attain low loadings while meeting commercial lifetime targets, factors such as ink formulation, MEA fabrication, catalyst layer–porous transport layer (CL–PTL) contact, and catalyst durability must be optimised. This review paper discusses the fundamentals of PEMWE technology and the modifications/improvements necessary for effective low iridium-loading design. Important milestones for future research include developing durable catalyst layers at low loadings, optimising the CL–PTL interface, and improving roll-to-roll production processes.

Quantification of Iridium Dissolution at Water Electrolysis Relevant Conditions Using a Gas Diffusion Electrode Half-Cell Setup

“…To achieve widespread commercial introduction of proton exchange membrane water electrolysis (PEMWE), the loading of iridium (Ir) in the anodic catalyst layer (CL) must be reduced significantly. , While the short-term performance of such ultralow loaded CLs improved significantly in recent years, − their long-term stability remains an open question . Of significant importance for the long-term stability of these CLs is the dissolution of the catalyst, for which fundamental studies strongly indicate a link between the oxygen evolution reaction (OER) activity and catalyst dissolution in an acidic environment .…”