Modification of Nafion Proton Exchange Membranes to Reduce Methanol Crossover in PEM Fuel Cells

Commercial sulfonated fluorocarbon membranes (Nafion) have been impregnated with poly(1‐methylpyrrole) by in situ polymerization. This can lead to a decrease of more than 90% in the permeability of the membranes to methanol, although the ionic resistance of such heavily loaded membranes becomes too high for high power fuel cells. At lower poly(1‐methylpyrrole) loadings, a decrease in methanol permeability by as much as 50% can be realized without a significant increase in ionic resistance. Such modified membranes can provide comparable performances to the original membranes in hydrogen fuel cells.