Methanol-rich domain

Many other inorganic materials such as Caj (PO ), BPO, ZrPO, etc., when blended with Nafion membranes will show improvement on the membranes properties such as thermal stability, proton conductivity, and lower methanol permeation. Nafion doped with cesium cations also show evidence of good performance in the operation of DMFCs. The presence of cesium ions in the membrane, specifically in the water-rich domains, causes a ranarkable reduction of methanol permeation [43]. However, the proton conductivity could be depressed to a lesser extent by the presence of the cesium ions in the membrane. Nevertheless, at ambient conditions, the combined parameter of both proton conductivity and methanol permeabiUty shows better performance of Cs -doped membranes than the Nafion 117 membranes in the operation of DMFC. Table 15.1, shows permeability values for Nafion 117 membrane and four different Nafion 117 modified membranes. A reduction in the permeability values when the Nafion 117 membrane is modified with appropriate methanol inhibiting material can be seen. A very sharp reduction is particularly noticed in the case of Cs -doped manbrane. This indicates that exchange of by Cs cations is very effective in reducing methanol content in the hydrophilic domains of Nafion. 

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