MSc.Thesis Defense:Faezeh Rahbarshendi

Electrospun Fe-N-C Based Electrodes for PEM Fuel Cells

Faezeh Rahbarshendi
Materials Science and Nanoengineering, MSc. Thesis Dissertation, 2024

Thesis Jury

Prof. Selmiye Alkan Gürsel(Thesis Advisor),

                                                                                                 Assoc. Prof. Enver Güler

Assıst. Prof. Alp Yürüm

Dr. Begüm Yarar Kaplan (Thesis Co-Advisor)

Date & Time: July 24th, 2024 –  13:30

                                                                                                   Place: Fens L029

                    Keywords : PGM-Free catalyst layer, Durability test, Fe-N-C, Cerium oxide, Core-shell electrospinning

Abstract

This thesis aims to develop electrospun single and core-shell nanofiber catalyst layers with Fe-N-C catalysts and PVDF/Nafion^® and investigate the addition of cerium oxide (CeO₂).

   In the first part of the thesis, hollow fiber commercial Fe-N-C catalysts and PVDF/Nafion^® fiber-based catalyst layers were fabricated and characterized. The results showed that the hollow fiber-based electrodes fabricated using core-shell electrospinning are a promising approach to obtaining enhanced fuel cell performance and durability. The novel hollow fiber structure fabricated by core-shell electrospinning, which has been introduced for the first time in the literature on PEM fuel cells, establishes a new benchmark for performance by attaining significant improvements in peak power densities and operational stability. Specifically, the core-shell fibers achieved a peak power density of 66 mW cm-² during the BOL test and 58 mW cm-² during the EOT test, resulting in 8% power loss, indicating excellent durability and stability over time. Additionally, the core-shell fiber maintained higher current densities during the EOT tests, demonstrating improved performance under prolonged operational conditions.

   The second part of the thesis focuses on fabricating electrospun catalyst layers using nano graphene-based Fe-N-C catalysts and PVDF/Nafion®. This part aims to investigate the effect of carbon support in the Fe-N-C structure and the resulting nanofiber-based catalyst layer structure and PEM fuel cell performance. Comprehensive characterizations confirm the presence of graphitic domains and the excellent dispersion of the catalyst within the fibrous matrix. This electrospun mat has been produced for additional evaluations of its operational performance, based on the results obtained during the initial phase.

   The thesis presents an approach to enhance the efficiency of PEM fuel cells by integrating state-of-the-art methods for material processing with inventive catalyst architectures. This will facilitate the advancement of clean energy technologies. The results emphasize the ability of core-shell structures to establish higher benchmarks in both efficiency and durability of PEM fuel cells.