Interface Optimization Between Porous Transport Layer and Catalyst Layer in Proton Exchange Membrane Water Electrolyzers

The porous transport layer (PTL) and the catalyst layer are two critical components in the proton exchange membrane water electrolyzer (PEMWE). The gas/liquid two-phase transport and electron/heat transfer between the two layers have a significant impact on the performance of the whole device. Catalyst layers and PTLs prepared by different methods or structures have unique effects. The coordination between the PTL and catalyst layer can greatly impact the catalyst and PEMWE performance, which is induced by the interface between the two. However, this coupled effect has not been well studied and the optimized interface mechanism is still unclear. In this work, three types of PTLs, including carbon paper, Ti felt and sintered Ti particles, were adopted, and their interfacial relationships between catalyst layers were investigated. We found that the interface between PTL and catalyst layer can be regulated by PTL structure, surface property, and catalyst layer thickness. The surface coating improves the electron transport at the interface and in the PTL itself, thereby increasing the local current density and weakening the influence of Schottky basis and pinch-off effects, and thus improving the PEMWE performance. The catalyst layer thickness could affect the in-plane electrical conductivity, which adjusts the active site distribution and enhances the local current density uniformity. This work reveals the coupled effects of PTL and catalyst layer on the interface and PEMWE performance, which provides the optimization strategy for the interface in PEMWE.