Synthesis and characterization of electrospun composite membranes for use in fuel cells

In this study; composite membranes prepared by mixing SHNT (sulfonated halloysite nanotube) and SPES (sulfonated polyethersulfone) with Polyvinylpyrilidon (PVP) as additive for use in fuel cell were synthesized by electrospinning technique. Then, the characterization of these synthesized membranes and their functionality in the fuel cell were investigated. For this purpose, both polymers were sulfonated with concentrated sulfuric acid in order to prevent the hydrophobicity of the Polyethersulfone and to increase the charge density of the Halloysite nanotube. Afterwards, membrane solutions were prepared by using 4 different mass percent of SHNT without changing the PVP additive ratios. The first of these membrane groups is the SPES/PVP control membrane that does not contain SHNT. Other membrane groups are SPES/PVP/0.5 SHNT membrane containing 0.5% SHNT, SPES/PVP/0.75 SHNT membrane containing 0.75% SHNT and SPES/PVP/1.0 SHNT containing 1.0% SHNT, named according to their mass percentage of SHNT. These membrane groups were prepared according to their percentage by mass, dissolved in Dimethylacetamide (DMAc): dimethylformamide (DMF) solvent mixture at a ratio of 70:30 (v/v) by volume and synthesized by electrospinning technique with appropriate parameters. Afterward, Nafion solution was impregnated into the structures of these synthesized membranes. Morphological, physicochemical, and mechanical properties of the synthesized membranes were determined by scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR), X-ray diffraction (XRD), Nuclear magnetic resonance (NMR) analysis. In addition, water uptake capacity, swelling property, fuel cell performance tests, and usability in fuel cells were examined. Both the water uptake capacity and the swelling property increased in direct proportion with the increase in the mass percentage of SHNT in the membranes. The result of the fuel cell performance test showed that the current density increases as the mass percentage of SHNT increases. As a result, SPES/PVP/1.0 SNHT membrane was evaluated as the most ideal membrane candidate for fuel cell among the synthesized membrane groups.