Porous transport layer influence on overpotentials in PEM water electrolysis at low anode catalyst loadings

Abstract

Achieving widespread use of polymer electrolyte membrane water electrolysis (PEMWE) for clean hydrogen generation requires enhancing the efficiency and utilization of low iridium-loaded electrolyzers. Novel porous transport layer (PTL) design and engineering can play a critical role in addressing this challenge. Despite the fact that the PTL is an important component of PEM electrolyzers, it has received little attention, particularly in terms of the mechanistic understanding of the influence of PTL characteristics on overpotentials. Herein, we investigate the impact of the PTL porosity, thickness, and structure on the PEM water electrolyzer performance. We demonstrate that improving the contact between PTL and the catalyst layer by inserting a microporous layer facilitates electron transfer and oxygen removal leading to reduced cell voltage. We observe that this strategy proves particularly effective at low catalyst loadings.