Degradation phenomena in PEMWE revealed by correlative electrochemical and nanostructure analysis

Abstract

Understanding degradation mechanisms in proton exchange membrane water electrolysis (PEMWE) is critical for advancing the long-term durability of the technology. In this study, we investigate degradation induced by four distinct accelerated stress test protocols through a combination of electrochemical diagnostics and quantitative ex situ characterization techniques. We identify multiple interconnected degradation pathways that strongly depend on the operational mode. A key finding is the dissolution of Pt-coating from the anode porous transport layer (PTL), which alters the interface between the PTL and catalyst layer and leads to Pt deposition within the membrane. This process potentially increases the risk of radical formation and chemical membrane degradation. Although Pt coatings on Ti-based PTLs are commonly used to prevent passivation and reduce contact resistance, their role in degradation has been largely overlooked, underscoring the need to assess PTL stability alongside that of the catalyst layers. Additionally, changes in the oxidation state of the Ir-based anode catalyst affect both activity and conductivity. Notably, a higher degree of oxidation is reached when cycling through redox transients compared to operation in steady oxidative regime.