-carrageenan/polyvinyl alcohol-graphene oxide biopolymer composite membrane for application of air-breathing passive direct ethanol fuel cells

In this article, new biopolymer composite membranes based on kappa-carrageenan, polyvinyl alcohol and graphene oxide (designated as kappa-car/PVA-GO) were synthesized by casting method for the application of passive direct ethanol fuel cell (DEFCs). FTIR, XRD, and FESEM analysis proved that the kappa-car/PVA-GO biopolymer composite membrane has been successfully fabricated. The fabrication of the kappa-car/PVA-GO biopolymer composite membrane effectively increases the proton conductivity and ethanol barrier. The high proton conductivity is achieved 2.67 x 10(-3) S/cm and the reduced permeability of ethanol 1.95 x 10(-7) cm(2)/s at 30 degrees C. Besides, PVA blend modification and the introduction of GO improve the mechanical properties of the kappa-car biopolymer. The maximum power density of the passive DEFCs is 3.84 mW/cm(2) using the kappa-car/PVA-GO biopolymer composite membrane, which is higher than the Nafion membrane, which achieved only 2.02 mW/cm(2) in a similar operating condition of passive DEFCs at 30 degrees C. Furthermore, the kappa-car/PVA-GO biopolymer composite membrane could be maintained in a fuel cell atmosphere for 1000 h. According to our review of the literature, there are no studies have used the carrageenan-based membrane in the application of passive DEFCs. This is a promising biopolymer electrolyte membrane for use in passive DEFCs.