Development novel eco-friendly proton exchange membranes doped with nano sulfated zirconia for direct methanol fuel cells

The proton exchange membrane is the main component of direct methanol fuel cells (DMFCs). It has binary function of separating oxidant and fuels, besides transporting protons. In this study, a binary polymer blend is formulated from inexpensive and ecofriendly polymers, such as iota carrageenan (IC) and poly vinyl alcohol (PVA). Super acidic sulfated zirconia (SO4ZrO2) was synthesized from an one pot, solvent free and simple calcination method and later embedded as a doping agent into the polymeric matrix with a percentage of 1-7.5 wt. %. The membranes formed were characterized by FTIR, TGA, DSC and XRD. The results revealed that, the oxidative stability and mechanical properties were enhanced with increasing doping addition due to an increase in numbers of hydrogen bonds formed between the polymers functional groups and oxygen functional groups of SO4 ZrO2. In addition to, the membrane with doping ratio of 7.5 wt. % of SO4 ZrO2 achieved methanol permeability of 1.95 x 10(-7) cm(2) s(-1) which much less than Nafion 117 ( 14.1 x 10(-7) cm(2) s(-1)) and ionic conductivity of 22.3 mS cm(-1) which is close to Nafion 117 (34 mS cm(-1)).

Automated summary

In this study, a binary polymer blend was formulated for the proton exchange membrane of direct methanol fuel cells. By doping super acidic sulfated zirconia into the polymeric matrix, the membrane showed improved oxidative stability and mechanical properties, as well as lower methanol permeability and comparable ionic conductivity to Nafion 117.