An electrospun hygroscopic and electron-conductive core-shell silica@carbon nanofiber for microporous layer in proton-exchange membrane fuel cell

In this study, a novel core-shell silica@carbon nanofiber (SiO2@C) is successfully prepared via coaxial electrospinning technique with optimized parameters followed by heat treatment. The characterizations of the nanofiber are carried out by a combination of X-ray diffraction measurement, electrical conductivity test, tensile test, thermogravimetric analysis, nitrogen isotherm adsorption-desorption analysis, mechanical strength test, and water uptake measurement. It is found that the hygroscopic mesoporous SiO2 is contained in a core and the hydrophobic electron-conductive carbon is in a shell that has porous channels. The BET surface area, pore volume, electrical conductivity, mechanical strength, and water uptake of SiO2@C are all superior to that of pure carbon nanofiber. These superior properties make SiO2@C a potential microporous layer (MPL) material, benefitting the water management ability of proton-exchange membrane fuel cells (PEMFCs). The result of the single-cell performance tests shows that under 99.9% or 15% relative humidity (RH) in the temperature range of 50–80 °C, the power densities of the PEMFC fabricated with the SiO2@C-based MPL are all significantly higher than that of the pure carbon nanofiber-based MPL, and 66~302% higher than that of the traditional hydrophobic carbon black powder-based MPL. This study indicates that the as-prepared novel core-shell SiO2@C nanofiber is a promising MPL material for PEMFC.