Understanding in-Plane Movement of Iridium in Proton Exchange Membrane Electrolyzer after Accelerated Stress Test

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In the rapidly evolving field of clean energy, proton exchange membrane water electrolyzers (PEMWEs) stand at the forefront, heralding a new era of sustainable hydrogen fuel production. PEMWEs need to operate for at least 10 years and material degradation is a challenge that needs to be overcome. Here we use H2NEW accelerated stress (AST) protocol to degrade 5 cm2 PEMWE cell having low iridium loadings on the anode side. Using X-ray fluorescence (XRF) mapping, we first assessed the iridium distribution at the beginning of life (BOL) of the electrolyzer cell and then afterwards at the end of life (EOL). Regular electrical characterization with specific time intervals was conducted, such as collection of polarization curves, electrochemical impedance spectroscopy and cyclic voltammetry. Identical location was selected for iridium mapping. To complement XRF mapping, we also conducted X-ray diffraction (XRD) studies at the BOL and at the EOL. XRD reveals the crystalline structure and phase transitions of iridium, crucial for understanding how iridium’s atomic arrangement adapts to operational stresses. This comprehensive approach, combining XRF and XRD, aims to provide a multifaceted view of iridium’s behavior, distribution, and structural changes from the BOL to EOL. This research aims to unravel the behavior of iridium after AST, particularly whether it migrates into the ionomer, moves to the cathode, or undergoes other transformational shifts.Figure 1.micro-XRF map of iridium distribution on the anode of the PEMWE at the BOL. The map is 2 mm x 2 mm. Figure 1