Nafion (R)/histidine functionalized carbon nanotube: High-performance fuel cell membranes
Here we show preparation and characterization of a new type of composite membrane based on Nafion (R)/histidine modified carbon nanotube by imidazole groups (Im-CNT), for direct methanol fuel cell (DMFC) applications. Due to the presence of this imidazole-based amino acid on the surface of CNT, new electrostatic interactions can be formed in the interface of Nafion (R) and Im-CNT. Physical characteristics of these nanocomposite membranes are investigated by water uptake, methanol permeability, ion exchange capacity, proton conductivity, as well as fuel cell performance results. Especially at elevated temperatures, Nafion (R)/CNT-0.5% membranes exhibit higher proton conductivities plus lower methanol crossover in comparison with commercial Nafion (R) membranes. Power density of nanocomposite membranes reached to 61 mW cm(-2) in contrast with 42 mW cm(-2) for Nafion (R) 117 (at 0.5 V and 5 M methanol concentration). Obtained results exposed that Nafion (R)/Im-CNT-0.5% membranes can be utilized as promising polyelectrolyte membranes for direct methanol fuel cell applications. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.