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The cross-linked and alkali stable alkaline anion exchange membranes (AAEMs) based on 1,2-dimethylimidazolium (proved to be much more stable than C2-unsubstituted imidazolium cation) were prepared by a hot-pressing method. The properties of these membranes, e.g., water uptake, swelling degree, ion-exchange capacity, conductivity and thermal and chemical stability, were characterized systematically. The swelling degree of the membranes decreases with the decrease of the amount of 1,2-dimethylimidazolium salt, up to 5.8%. The membranes are thermally stable below 200 °C. Alkaline direct methanol fuel cell (ADMFC) fabricated by using CoO x /C as the cathode catalyst and PtRu/C as the anode catalyst presents a promising performance with the peak power density of 12.7 mW cm −2 at a current density of 45 mA cm −2 , indicating that the 1,2-dimethylimidazolium-functionalized AAEMs are promising for the application in ADMFCs. [ABSTRACT FROM AUTHOR]

Abstract: Gas diffusion layers (GDLs) of direct methanol fuel cells (DMFCs), consisting of a microporous layer (MPL) and a back layer (BL), influence the cell performance and stability significantly due to the critical function that the GDL undertook, i.e., distribution of reactants and removal of the products in electrodes. The hydrophilic/hydrophobic properties of the GDLs are required to tailor to the transport/transfer of reactants/products depending on a specific electrode reaction. One important way to adjust the hydrophobic/hydrophilic properties of GDLs is to vary PTFE content in GDLs. In this paper, we employ infrared spectroscopy technique, specifically, diffuse reflection (DR) method and attenuation total reflection (ATR) method, to determine the PTFE content in both MPLs and BLs quantitatively by comparing the measured C-F intensity with the pre-calibrated standard plots. Compared to the ATR method, the DR method takes advantages of sensitivity, wide range and precision. By the DR method, we succeed in observing that PTFE in MPLs migrates to BLs, consistent with the corresponding EDX results for a sample experienced 600 h lifetime test, suggesting DR method an effective approach to determine quantitatively the hydrophilic/hydrophobic properties of both MPLs and BLs. [Copyright &y& Elsevier]