To decarbonize our society, green hydrogen produced by water electrolysis using renewable electricity is a promising pathway. However, today's electrolyzers rely on fluorinated polymers (PFAS), which face upcoming restrictions in Europe due to their environmental impact. Fluorine-free alternatives, namely hydrocarbon (HC) ionomers, are making progress in membranes, but their use in electrodes still yields limited performance, most likely due to poor dispersion of the ionomer within the electrode.
The electrode under study is a nanoporous material made of carbon aggregates supporting the catalyst (Pt nanoparticles) and bound together by the ionomer. The spatial distribution of the ionomer plays a decisive role, as it must provide ionic conduction to the catalytic sites without obstructing gas transport. Visualizing this ionomer is a significant challenge, as it forms a thin film only a few nanometers thick covering the carbon. Our group has acquired unique expertise in imaging this ionomer using electron tomography (E-TOMO). In the case of fuel cells (PEMFC), where the ionomer is fluorinated, this approach has made it possible to understand its distribution within the electrode.
The objective of this PhD project is to build upon this expertise to provide the first 3D images of HC ionomer distribution in electrodes. The methodology will be optimized to reduce analysis times by leveraging recent advances in the field. Analyses performed on various electrodes will provide key insights to optimize their fabrication process, better understand their performance, and assess their stability. E-TOMO will thus play a central role in advancing the development of fluorine-free electrodes for AEMWE electrolyzers.