Unveiling the Structure and Catalytic Mechanism of Iridium in Zero-gap Water Electrolyzers via Operando X-ray Diffraction

Large-scale deployment of proton exchange membrane water electorlysis (PEMWE) is limited by the scarcity of Ir used as the catalyst for the sluggish oxygen evolution reaction taking place on the anode. Deep understanding of Ir degradation mechanisms is therefore pivotal for efficiently lowering the currently used Ir loadings by at least an order of magnitude. Despite significant research progress within the PEMWE community in the past decade, spatially-resolved dynamics of catalytic and structural Ir adaptions within membrane electrode assemblies at the initial stages of electorlyzer performance remain unresolved. Consequently, no consensus on the conditioning procedures for efficient intra-lab comparative analyses on PEM water electrolyzer performance decay has been reached so far. Here we employ operando high energy X-ray diffraction in zero-gap electorlyzer configuration to study the activity and stability changes of Ir during various break-in procedures and extensive stress tests.