Exploring the degradation of catalyst layer and porous transport layer in proton exchange membrane water electrolyzers

Abstract

Proton exchange membrane water electrolyzers (PEMWEs) are among the emerging technologies for hydrogen production due to their high operational current density, low operating temperature, and ultra-pure hydrogen production. However, industrial scale hydrogen production via PEMWEs is greatly hindered by the interrelated trio-factor of low performance, limited durability, and high cost. The iridium-based catalyst layer (CL) and platinum-coated titanium-based porous transport layer (PTL) are the core components which primarily contribute to the performance, durability and cost of PEMWEs. The degradation of costly CL and PTL (due to Ir and Pt usage) is a significant challenge for wider development of PEMWEs. In this review, we discuss the degradation of CL and PTL and provide an overview of the diagnostic techniques used to investigate the degradation processes. In situ and ex situ analysis reveal that the future development of CL should be focused on ink properties optimization and catalyst coated membrane fabrication methods, which affect the CL architecture and performance. Similarly, the titanium passivation, corrosion and increased interfacial contact resistance are the key factors that affect the PTL microstructure and performance. Thus, it is crucial to develop corrosion resistant coating and incorporation of low-cost materials as interlayers to reduce the cost without compromising the stability of PTL. The understanding of CL and PTL degradation and their characterization methods along with future perspectives will guide the development of durable and low-cost CL and PTL for wider applications of PEMWEs.