Pectin based nanocomposite membranes as green electrolytes for direct methanol fuel cells

Abstract

Biocomposite materials are highly attractive for research and industrial application due to biodegradability, nontoxicity and sustainability. Solid electrolyte membrane derived from biodegradable materials broadens scope of using sustainable polymers and is easily disposable at the end of life cycle. In this study, Pectin (PC) is blended with polyvinyl alcohol (PVA) in order to fabricate new class of hybrid nanocomposite followed by addition of sulfonated titanium dioxide (s-TiO2) nanoparticles as inorganic proton conducting material. PVA and PC is in situ cross-linked using dual cross-linker comprising a mixture of sulfosuccinic acid and glutaraldehyde followed by solvent casting. Rheological studies with polymer solutions are conducted to study alignment and disentanglement of polymer chains at molecular level. It is shown that rational design of membrane microstructure with proper arrangement of hydrophobic/hydrophilic domains has been formulated by blending PVA with PC. PC-PVA blends with a flexible polymeric network which is appropriate to disperse rigid s-TiO2 nanoparticles resulting in improved proton conductivity and restricted methanol permeability. With further enriched proton conductivity by the presence of s-TiO2 nanoparticles, fabricated PC-PVA/s-TiO2 hybrid nanocomposite membrane exhibit a peakpower density of 27 mW/cm2 at 70 °C in DMFCs. Keywords: Pectin, Polyelectrolytes, Hydrophobic/hydrophilic domains, Methanol permeation