On the Methanol Permeability through Pristine Nafion® and Nafion/PVA Membranes Measured by Different Techniques. A Comparison of Methodologies

Abstract

Methanol crossover through polymer electrolyte membranes is a critical issue and causes an important reduction of performance in direct methanol fuel cells (DMFCs). Measuring the evolution of CO2 gas in the cathode is a common method to determine the methanol crossover under real operating conditions, although an easier and simpler method is preferable for the screening of membranes during their step of development. In this sense, this work has been focused on the ex situ characterization of the methanol permeability in novel nanofiber‐reinforced composite Nafion/PVA membranes for DMFC application by means of three different experimental procedures: (a) potentiometric method, (b) gas chromatography technique, and (c) measuring the density. It was found that all these methods resulted in comparable results and it was observed that the incorporation of the PVA nanofiber phase within the Nafion® matrix causes a remarkable reduction of the methanol permeability. The optimal choice of the most suitable technique depends on the accuracy expected for the methanol concentration, the availability of the required instrumental, and the complexity of the procedure.

Electrospun Nanofibers for Design and Fabrication of Electrocatalysts and Electrolyte Membranes for Fuel cells

“…For example, with the [ 100] addition of cross-linked PVA nanofibers, the proton conductivity of Nafion/PVA composite membranes was reduced to 0.025 S/cm compared with 0.096 S/cm for Nafion 117. This value could be further reduced to around 0.01 S/cm with IEC value reduced from 0.58 to 0.33 meq/g, compared with the IEC value of 0.91 meq/g for Nafion 117 [73][74][75][76]. Similar phenomenon was evident with the use of Nafion/PVDF [77], Nafion/SiO 2 -coated polyetherimide composite membranes [39], etc., as the proton exchange membranes.…”

“…Similar phenomenon was evident with the use of Nafion/PVDF [77], Nafion/SiO 2 -coated polyetherimide composite membranes [39], etc., as the proton exchange membranes. In addition, with the filling of longrange one-dimensional nanofibrous materials, a series of other properties of the membranes were significantly improved, such as the mechanical properties [73][74][75][76], hydrolytic stability [79], reduced methanol crossover [73][74][75][76], and so forth.…”

Nanocomposite SPEEK-based membranes for Direct Methanol Fuel Cells at intermediate temperatures

“…A typical 2-cell experimental setup [43] was used to measure the coefficient of methanol permeability across the SPEEK-35%PVA and nanocomposite membranes as a function of crosslinking temperature. The donor chamber (D) was filled with a 2 M aqueous solution of methanol, while the receptor chamber (R) was filled with distilled water.…”

Regulation of micromorphology and proton conductivity of sulfonated polyimide/crosslinked PNIPAm semi‐interpenetrating networks by hydrogen bonding

“…This is ascribed to the diluted density of proton conductive groups in the organic − inorganic hybrid membranes. On the other hand, the modification of proton exchange membranes by using different organic materials such as polyvinyl alcohol (PVA), polypyrrole, chitosan, polyethylene oxide (PEO) and cyclodextrin has been reported in the literature. Nicholas WD et al prepared blend membranes of Nafion and PVA, and the membranes exhibited a decrease in methanol permeability by a factor of 3 compared with pure Nafion .…”