Development of a Chitosan/PVA/TiO2 Nanocomposite for Application as a Solid Polymeric Electrolyte in Fuel Cells

Abstract

The influence of the incorporation of nanoparticles of titanium oxide (TiO2) at a concentration between 1000 and 50,000 ppm on the physicochemical and mechanical properties of a polymer matrix formed from a binary mixture of chitosan (CS) and polyvinyl alcohol (PVA) at a ratio of 80:20 and the possibility of its use as a solid polymeric electrolyte were evaluated. With the mixture of the precursors, a membrane was formed with the solvent evaporation technique (casting). It was found that the incorporation of the nanoparticles affected the moisture absorption of the material; the samples with the highest concentrations displayed predominantly hydrophobic behavior, while the samples with the lowest content displayed absorption values of 90%. Additionally, thermogravimetric analysis (TGA) showed relatively low dehydration in the materials that contained low concentrations of filler; moreover, differential scanning calorimetry (DSC) showed that the nanoparticles did not significantly affect the thermal transitions (Tg and Tm) of the compound. The ionic conductivity of the compound with a relatively low concentration of 1000 ppm TiO2 nanoparticles was determined by complex impedance spectroscopy. The membranes doped with a 4 M KOH solution demonstrated an increase in conductivity of two orders of magnitude, reaching values of 10−6 S·cm−1 at room temperature in previously dried samples, compared to that of the undoped samples, while their activation energy was reduced by 50% with respect to that of the undoped samples. The voltage–current test in a proton exchange membrane fuel cell (PEMFC) indicated an energy efficiency of 17% and an open circuit voltage of 1.0 V for the undoped compound, and these results were comparable to those obtained for the commercial membrane product Nafion® 117 in evaluations performed under conditions of 90% moisture saturation. However, the tests indicated a low current density in the undoped compound.

Enhancement in hydrolytic stability and proton conductivity of optimised chitosan/sulfonated poly(vinyl alcohol) composite membrane with inorganic fillers

“…For T m , the addition of inorganic fillers was reported to have an extremely weak effect towards the CS/SPVA15 composite membrane. The result is similar to Wang et al 82 and Ruiz Gomez et al's 83 work, where the inorganic filler caused minimal influence on the crystalline part of the polymer matrix.…”

Metal oxide-based materials as an emerging platform for fuel cell system: A review

“…Ruiz Gómez et al [188] evaluated the influence of TiO 2 nanoparticles on physicochemical properties and mechanical stability of polymer matrix produced from a binary mixture of CS and PVA at a ratio of 80:20. A nanocomposite membrane was prepared through solution casting procedure with the mixture of the precursors.…”

Study of the humidity effect on the mechanical properties of PVOH+H3PO2/TiO2 proton exchange membranes

“…The observation of high-proton conductivity in acid-doped PVOH membranes has opened up the possibility of using these polymers in solid-state ionic devices. Furthermore, doping with salts, acids, or inert micro or nanoparticles (TiO2, Al2O3, ZrO2, SiO2) have shown changes in their electrical, thermal, and mechanical properties [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23]. In this work, we studied water concentration and the nanoparticles fillers' effect, on the mechanical properties in the PVOH + H3PO2 + TiO2 system, by performing tensile stress-strain tests in all the concentration ranges mentioned above.…”