Influence and Improvement of Membrane Electrode Assembly Fabrication Methods for Proton Exchange Membrane Water Electrolysis

The performance of proton exchange membrane water electrolysis (PEMWE) is crucial for its commercialization. The membrane electrode assembly (MEA) preparation process determines the catalyst layer’s (CL) structure, thereby influencing PEMWE performance. Herein, the effects of conventional preparation methods, i.e., direct spray deposition and decal transfer, on the CL were investigated. It was found that the MEA prepared via the decal process exhibits lower activation and Ohmic overpotential. For decal transfer CL, this is due to the improved electrochemically active surface area and proton conduction, derived from the improved catalyst-ionomer agglomerates interconnection and CL-membrane interfacial contact. For direct spray deposition CL, the crack and larger pores in CL facilitate its water-gas transport. On this basis, a hierarchical CL was designed in order to combine the advantages of direct spray deposition and decal transfer. As a result, the hierarchical CL shows better performance than both direct spray deposition and decal transfer CL. The Ohmic and mass transfer losses are reduced by 13% and 15% at 4 A cm −2 , respectively. This work provides valuable insights for MEA development, crucial for the large-scale application of PEMWE. The difference between direct spray deposition and decal transfer is investigated. The hot-press process enables reduced activation and Ohmic losses. The direct spray deposition method enables reduced mass transport loss. A hierarchical CL design that combines the advantages of direct spray deposition and decal transfer shows a better performance.