Surface modification of sulfonated polyethersulfone membrane with polyaniline nanoparticles for application in direct methanol fuel cell

Abstract

A novel polyion nanocomposite membrane was synthesized by doping the surface and matrix of sulfonated polyethersulfone (SPES) with polyaniline (PANi) nanoparticles to facilitate proton conduction in direct methanol fuel cell (DMFC) application. The synthesized membrane exhibited effective, ionic interaction, dense morphology with high thermal stability, adequate tensile strength (60 Mpa) and considerable ion exchange capacity (2.2 meq g−1). The membrane exhibited low methanol permeability of 7.46 × 10−8 cm2s−1 with high proton conductivity (0.098 Scm−1) besides adequate hydrolytic and oxidative stabilities. A maximum power density of 99 mWcm−2 at a current density of 250 mAcm−2 was obtained with a single slice fuel cell setup. Molecular dynamics simulation based on the COMPASS force-field was applied to investigate the influence of PANi nanoparticles, temperature and hydration level on the diffusivity of hydronium ions. Rapid mass transfer of hydronium ions within the PANi incorporated SPES membrane, could be achieved at higher temperatures and hydration levels. Analysis by radial distribution function (RDF) revealed extensive interactions of sulfonic acid groups of SPES and amine groups of PANi with water molecules. The polyion complex membrane was found to exhibit significant prospect of scale-up for potential application in DMFC.