On the Proton Conductivity of Nafion-Faujasite Composite Membranes for Low Temperature Direct Methanol Fuel Cells.

摘要

Although zeolites are introduced to decrease methanol crossover of Nafion membranes for directudmethanol fuel cells (DMFCs), little is known about the effect of their intrinsic properties and theudinteraction with the ionomer. In this work, Nafion-Faujasite composite membranes prepared by solutionudcasting were characterized by extensive physicochemical and electrochemical techniques. Faujasite wasudfound to undergo severe dealumination during the membrane activation, but its structure remainedudintact. The zeolite interacts with Nafion probably through hydrogen bonding between Si-OH and SO3Hudgroups, which combined with the increase of the water uptake and the water mobility, and the additionudof a less conductive phase (the zeolite) leads to an optimum proton conductivity between 0.98 and 2udwt% of zeolite. Hot pressing the membranes before their assembling with the electrodes enhanced theudDMFC performance by reducing the methanol crossover and the serial resistance.