Electrospun Nanofiber Catalyst Support for Polymer Electrolyte Membrane Fuel Cells

Abstract

Increased energy demand and environmental concerns are driving the search for cleaner, more efficient power generation. Fuel cells (FCs) offer a solution by converting chemical energy from fuel and oxidant directly into electricity with high efficiency (40-70%) and zero carbon emissions. Enhancing the performance and durability of polymer electrolyte membrane fuel cells (PEMFC) while reducing costs remains a significant challenge. The current planar FC design presents various issues, including high costs and weight due to metal or graphite bipolar plates, high-pressure drop-in reactant gas diffusion channels, reactant gas transport losses in the agglomerate-type catalyst layers, water flooding, to name just a few. Exploring novel biomimetic designs may offer solutions to these challenges.This research is inspired by vascular plant structures to improve mass transport and efficiency. The cathode uses carbon nanofibers (CNF) made via electrospinning, with Pt nanorod catalyst on the surface in an open electrode layout. This CNF-type cathode was used to create a membrane electrode assembly (MEA), using a commercial membrane and typical anode. A number of parameters were varied, including overall Pt loading, Pt concentration on the fibers, design with and without gas diffusion layer, using CNF mat. The MEAs were tested to establish links between structure, properties, and performance. Performance was evaluated through polarization curves and electrochemical impedance spectroscopy, while beginning of test and end of test structure was investigated using microscopy. CNF-based MEAs achieved a higher current density compared to the commercial MEA at lower Pt loading. This suggests that reduced loading still maintained acceptable Pt utilization, reducing the Pt amount in the MEA. In summary, the CNF catalyst support displayed improved durability, mass transport, Pt utilization, and efficiency thanks to its porous mesh structure.