Reducing interfacial resistances in proton exchange membrane water electrolysis via gas diffusion layer-based layer-by-layer coating

Abstract

Efficient membrane electrode assembly (MEA) fabrication is essential to reduce voltage losses in proton exchange membrane (PEM) water electrolysis. However, conventional assembly techniques often result in discrete membrane-electrode interfaces that increase contact resistance. Here, we systematically compare traditional decal transfer and catalyst-coated membrane methods with integrated layer-by-layer (LbL) architectures using self-cast membranes as a common reference to isolate fabrication effects. Sequential wet-on-dry coating of the cathode catalyst layer, membrane dispersion, and anode catalyst layer directly onto a gas diffusion layer (GDL) reduces the area-specific ohmic resistance by 60% (45.2 vs. 112 . 5 m Ω cm 2 ) relative to the decal-transferred reference, enabling 1 . 63 V at 1 . 0 A cm − 2 ( 120 mV lower than the decal transferred sample using a selfmade membrane). In addition, eliminating hot pressing preserves a more porous catalyst-layer morphology and lowers the kinetic overpotential. Cross-sectional microscopy reveals a 3D interfacial transition zone, including catalyst penetration into the GDL microporous layer, consistent with reduced electronic and ionic contact resistances. These results identify interfacial architecture as a practical lever for improving PEMWE MEA performance while simplifying manufacturing workflows. • A monolithic PEMWE MEA was fabricated via sequential layer-by-layer GDL coating. • GDL-LbL reduced interfacial resistance by 68% compared to decal transfer. • Omitting hot-pressing preserved catalyst porosity and enhanced mass transport.