Browsing by Author "Naffati, Naima"
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- Chitosan doped membranes for electrochemical devices [Resumo]Publication . Naffati, Naima; Teixeira, Fatima; Teixeira, António P. S.; Rangel, C. M.ABSTRACT: The development of new proton exchange membrane (PEM) for electrochemical devices, such as fuel cells and electrolyzers, have attracted researcher’s attention in the pursuit for more sustainable and cost-effective technologies for clean energy production, being extensive those for CO2 reduction and conversion1,2. To this end, in the present work, new modified chitosan (CS) membranes doped with ionic liquids (ILs) were developed to perform as PEM at those electrochemical devices, as an alternative to widely used commercial Nafion, with several advantages such as wider availability, lower cost, biodegradability and thermal stability. These modified membranes for use in electrochemical devices are expected to show suitably enhanced ion conductivity and also improved mechanical strength associated to a decrease in water uptake.
- Enhancing Conductivity in PEM Chitosan Membranes through Bisphosphonate Graphene Oxide [Resumo]Publication . Naffati, Naima; Teixeira, Fatima; Teixeira, António P. S.; Rangel, C. M.
- New proton exchange membranes based on ionic liquid doped chitosanPublication . Naffati, Naima; Teixeira, Fatima; Teixeira, António Paulo Silva; Rangel, Carmen M.ABSTRACT: The development of new proton exchange membranes (PEM) for electrochemical devices have attracted researcher's attention in the pursuit for more sustainable and cost-effective technologies for clean energy production and conversion. In this work, new doped chitosan (CS) membranes were prepared by the casting method. Chitosan is an abundant, biodegradable and non-toxic material, and as a membrane, a sustainable and cheaper alternative to those perfluorinated and commonly used, such as Nafion. Three different ionic liquids were employed as dopants, ([EMIM][OTf], [EMIM][FSI] and [MIMH][HSO4]), in various concentrations and up to 50 wt% load. The new membranes were characterized by ATR-FTIR, thermogravimetry, using TGA and DSC techniques to assess their thermal properties, and by SEM, to analyse their surface morphology. Proton conduction properties of the new membranes were assessed by Electrochemical Impedance Spectroscopy (EIS). The new doped membranes showed an increase in the proton conduction compared with pristine chitosan membranes. The incorporation of ionic liquids into chitosan membranes improved their proton conductivity and thermal properties, with [EMIM][OTf] and [MIMH][HSO4] showing the most promising results. A 2-fold increment in the proton conduction was generally observed with the increase of the temperature from 30 to 60 degrees C. The best proton conductivity was found at 60 degrees C for the membrane doped with [EMIM][OTf], with a value of 47 mS.cm(-1).