Chitosan-sodium alginate polyion complexes as fuel cell membranes

The viability of using polyion complex (PIC) membranes made by blending 84% deacetylated chitosan and sodium alginate biopolymers for direct methanol fuel cell (DMFC) was investigated. The membranes were characterized by FTIR to verify the polyion complex formation, XRD to observe the effects of blending on crystallinity, DSC and TGA to assess the thermal stability, and tensile testing for mechanical stability. Absorption studies were carried out to evaluate the interaction with water and methanol. The blend was found to be suitable for DMFC applications because of the low methanol permeability (4.6 × 10⁻⁸ cm²/s at 50 vol.% methanol concentration), excellent physico-mechanical properties and relatively high proton conductivity (0.042 S cm⁻¹). Above all, the cost effectiveness and simple fabrication technique involved in the synthesis of such PICs make their applicability in DMFC quite attractive and cost-effective.