14, 15 Since this discovery RTILs have been an area of increased study for use in PEM-HFCs. It was first reported in 2003 that Brønstead acid-base type RTILs are suitable electrolytes for fuel cells. 1, 2, 8, 10, 11 At these high temperatures the carbon monoxide poisoning of the platinum catalyst is reduced due to the thermal instability of the Pt–CO surface products, 13 allowing lower grade hydrogen fuel sources to be used.Ĭost could further be reduced if a supplementary polymer membrane, or a liquid membrane cell, could be developed eliminating the need for the Nafion altogether. 1, 2, 6 - 12 The membranes that incorporate imidazole- or imidazolium-based room-temperature ionic liquids (RTILs) are an attractive subset of these membranes, as they are conductive at temperatures of 100☌ or higher using dry gases. To increase the operating temperature of a PEM-HFC, Nafion membranes containing imidazolium salts, 1, 2 silica, 3 poly(tetrafluoroethylene), 4 zirconium phosphate, 5 and sulfated zirconia 5 have been explored in addition to alternative polymer membranes. These limitations add to the overall cost of Nafion-based PEM-HFCs. In addition, the low operating temperature requires ultrapure hydrogen gas to be supplied to the anode in order to prevent poisoning of the platinum catalyst. At higher temperatures the water in the Nafion membrane evaporates and the membrane loses its ability to conduct protons. A low operating temperature is necessary to keep the Nafion membrane hydrated. Current drawbacks preventing the wide scale adoption of PEM-HFCs include the high cost of the Nafion membrane used in these devices and the low operating temperatures ( < 80☌). Proton exchange membrane hydrogen fuel cells (PEM-HFCs) are among the most attractive sources of alternative power due to their high output power density. These studies give further insight into the possible mechanism of proton transport in these RTIL systems.Īn increase in global energy demand coupled with the escalating costs of petroleum-based energy has prompted a growing interest in developing alternatives to fossil fuels. The water structure in these RTILs was examined using attenuated total internal reflection Fourier transform IR spectroscopy and depended on the chemical structure of the cation. The efficiency of the C 12mimBETI increased upon removal of water while that of the C 12imBETI decreased in efficiency when water was removed. The effect of water content on the reaction rates and thermodynamics of these hydrophobic RTILs was also examined. However, when used in the electrochemical system the protic water-equilibrated C 12imBETI had a larger maximum current and power density compared to the aprotic water-equilibrated C 12mimBETI. The ionic conductivities of C 12mimBETI and C 12imBETI were similar and increased linearly with an increase in temperature from 20 to 130☌. In the presence of calcium ions, the carbonate ions precipitate as insoluble calcium carbonate, the major component of boiler scale.In this study 1-dodecyl-3-methylimidazolium (C 12mim) bis(pentafluoroethylsulfonyl)imide (BETI) and 1-dodecylimidazolium (C 12im) BETI hydrophobic room-temperature ionic liquids (RTILs) were synthesized and used as proton-conducting electrolytes in a nonhumidified feed gas electrochemical cell. \), which escapes into the gas phase above the solution.
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