Chemical Engineering Journal · 2025 · 18 citations · 79 references
Natural SciencesChemical EngineeringMaterials ScienceElectrochemical EngineeringElectrochemistryEnergy MaterialsAnode MaterialsElectrochemical CellsElectrode MaterialsElectrode-electrolyte InterfacesMembrane EngineeringMembrane MaterialsAnode PerformanceElectrolyzersMembrane PerformanceMicroporous StructurePolymer Electrolyte MembranesPorous Transport LayersProton Exchange Membrane ElectrolysisProton Exchange Membranes
Reducing the dependency of proton exchange membrane water electrolyzers (PEMWE) on precious metals, such as iridium (Ir), is necessary to develop a widespread green hydrogen system. This challenge requires a careful design of the interface between the anode porous transport layer (PTL) and the catalyst layer (CL). A comprehensive numerical analysis of relevant parameters that govern the behavior of the anode PTL/CL interface is presented. Calculations are also combined with an experimental characterization of the thickness and electrical conductivity of an unsupported CL as a function of Ir loading. The results show that the in-plane electrical resistance at the anode PTL/CL interface plays a critical role in cell performance. Reaching an acceptable electrical resistance at low Ir loading ( L Ir ≃ 0 . 1 mg Ir , cm − 2 ) can be accomplished through the incorporation of a micrometer-sized microporous layer (MPL) onto the PTL or the preparation of bimodal CLs with a secondary conductive phase. Further reduction of the Ir loading to the ultra-low regime ( L Ir ≲ 0 . 1 mg Ir , cm − 2 ) may require the use of nanometer-sized MPLs with unsupported CLs or micrometer-sized MPLs with bimodal CLs. Furthermore, the decline of the volume reactive area at ultra-low Ir loading needs a maximization of the exchange current density and the specific electrochemical surface area, and a decrease of the catalyst oxygen coverage factor in the anode CL. • A 2D parametric analysis of key factors of the anode PTL/CL interface is presented • In-plane CL electrical resistance at PTL interface plays a critical role on performance. • Low Ir loading ( 0 . 1 mg Ir , cm − 2 ) can be achieved with micrometer-sized MPL or bimodal CL. • Ultra-low Ir loading ( ≲ 0 . 1 mg Ir , cm − 2 ) can be reached with fine MPLs and bimodal CL. • Optimization of volumetric exchange current density and gas saturation is needed.
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