Nafion / Silicon oxide / phosphotungstic acid nanocomposite membrane with enhanced proton conductivity.

Abstract Nafion-silicon oxide (SiO 2 )-phosphotungstic acid (PWA) composite membrane has been synthesized to improve Nafion based proton exchange membrane fuel cell (PEMFC) performance. The objective of the study is to fabricate Nafion-SiO 2 -PWA nanocomposite membrane using sol–gel reaction. The composite is composed of the mixture of Nafion solution, tetra ethoxy orthosilane (TEOS) and PWA solution. The mixed solution was casted at certain temperature until transparent membrane is obtained. Peaks of SiO 2 and PWA in the infrared spectra revealed that both inorganic and organic components are present in the modified Nafion based nanocomposite membrane. Analysis with fuel cell test station showed that higher current density was produced by nanocomposite membrane (82 mA cm −2 at 0.6 V for NS15W) than with the Nafion membrane (30 mA cm −2 at 0.2 V) at 90 °C and 40% relative humidity. The internal resistance was seen to increase with the inorganic content. The internal resistances of the commercial Nafion (N112), NS10W, NS15W and NS20W are 6.33, 4.84, 1.33 and 3.6 Ω cm 2 , respectively and their Tafel constants are 93.4, 84.4, 11.25 and 26.6 mV, respectively. While the nanocomposite membrane results were shown to be better than the commercial Nafion, the overall performances are comparable to those in the open literature.

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