Novel nanofiber-based triple-layer proton exchange membranes for fuel cell applications

New types of triple-layer membranes were fabricated using multi-step impregnation of Nation in electrospun webs based on bead-free nanofibers of sulfonated poly(ether sulfone) (SPES). The results showed that the fabricated nanofiber-filled membrane owing to its reduced methanol permeability as well as sufficient proton conductivity and membrane selectivity can be used as a promising proton exchange membrane for direct methanol fuel cell (DMFC) applications. The single cell DMFC performance results revealed that the SPES nanofiber-based triple-layer membranes have higher electrochemical performance than commercial Nation membranes. (C) 2011 Elsevier B.V. All rights reserved

Prepration and Characterization of Novel Ionoic Polymers to beUsed as Artificial Muscles: Novel ionic polymers for artificial muscles

The muscle-like technology would be of enormous advantages for biomedical applications such as medical implants and human assist devices. Ionic polymer metal composites (IPMCs) are one kind of biomimetic actuators. An ionic polymer metal composite composed from an ionomer with high ion exchange capacity that packed between two thin metal layers. In the present study we focused on the preparation of a novel alternative polymeric ionomer to be used as artificial muscles. Sulfonated poly(ether ether ketone) (PEEK) have been synthesized as a new class of ionomeric membrane materials. PEEK was sulfonated at various degrees with sulfuric acid and N,N-Dimethylacetamide as a solvent. Fourier transfer infrared spectroscopy confirmed the quality of substitution reaction. Sulfonated samples showed O-H vibration at 3490 and S=O peaks at 1085 and 1100-1300 cm-1. By increasing degree of sulfonation to 80%, ion exchange capacity, water uptake and the number of water molecules per the fixed sulfone groups (λ) were increased to about 2.4 meq.g-1, 75% and 19, respectively. After calculating the optimum degree of sulfonation, the applications of these ionomers as actuators are studied. Rigid microstructure of PEEK backbone causes to slow displacement. However, this inflexible backbone showed the acceptable tip force during its actuation. These IPMC are easy to prepare and much less expensive than the commercial per-fluorinated membranes such as Nafion®. The results approve the utilization of sulfonated aromatic for artificial muscles applications as novel strong muscles with low flexibility

A high-performance chitosan-based double layer proton exchange membrane with reduced methanol crossover

A novel double layer proton exchange membrane (PEM) comprising a layer of structurally modified chitosan, as a methanol barrier layer, coated on Nafion (R) 112 was prepared and assessed for direct methanol fuel cell (DMFC) applications. Scanning electron microscope (SEM) micrographs of the designed membrane revealed a tight adherence between layers, which indicate the high affinity of opposite charged polyelectrolyte layers. Proton conductivity and methanol permeability measurements showed improved transport properties of the designed membrane compared to Nafion (R) 117. Moreover, DMFC performance tests revealed a higher open circuit voltage and power density, as well as overall fuel cell efficiency for the double layer membrane in comparison with Nafion (R) 117, especially at elevated methanol solution feed. The obtained results indicate the designed double layer membrane as a promising PEM for high-performance DMFC applications

Nafion/chitosan-wrapped CNT nanocomposite membrane for high-performance direct methanol fuel cells

Here we show that the transport properties and electrochemical performance of polyelectrolyte membranes are improved through the dispersion of chitosan-wrapped carbon nanotubes, for direct methanol fuel cell applications. Methanol permeability is reduced via improving the interfacial interactions and the solubilization of CNTs in the Nafion matrix, as well as inducing the formation of long-range oriented conduction pathways in the vicinity of the decorated one-dimensional nanostructure. The improved membrane selectivity results in a considerably enhanced fuel cell efficiency (16% vs. 11%) and a power generation capacity more than two times higher (110 mW cm−2vs. 47 mW cm−2) in a concentrated methanol solution (5 M), in comparison with the commercial Nafion®117 membrane

Microfluidic synthesis of chitosan-based nanoparticles for fuel cell applications

A microfluidic platform is developed for the synthesis of monodisperse, 100 nm, chitosan based nanoparticles using nanogelation with ATP. The resulting nanoparticles tuned and enhanced transport and electrochemical properties of Nafion based nanocomposite membranes, which is highly favorable for fuel cell applications

Direct methanol fuel cell performance of sulfonated poly (2,6-dimethyl-1,4-phenylene oxide)-polybenzimidazole blend proton exchange membranes

Various sulfonated poly (2,6-dimethyl-1,4-phenylene oxide) (SPPO)-polybenzimidazole (PBI) blend membranes were prepared and investigated as proton exchange membranes (PEMs) for direct methanol fuel cell (DMFC) applications. With increasing PBI content water swelling, ion exchange capacity, proton conductivity and methanol permeability of SPPO-PBI membranes were found to be decreased due to acid-base interactions between sulfonate and the amine groups of the blended components. Among various SPPO-PBI blend membranes, 80:20 wt% was found as the optimum composition, which showed the highest membrane selectivity parameter. Direct methanol-air single fuel cell tests revealed a higher cell efficiency of 11.6% for SPPO80-PBI20 than 10.9% for Nafion (R) 117 at 5 M methanol feed, and also a higher power density of 57.6 mW.cm(-2) compared to 39.4 mW.cm(-2) for Nafion (R) 117. Transport properties as well as DMFC performance results of SPPO-PBI blend PEMs converge to indicate their potential for DMFC applications. Copyright (C) 2010, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved

Morphological Tuning of Polymeric Nanoparticles via Microfluidic Platform for Fuel Cell Applications

At nanoscale length scales, the properties of particles change rapidly with the slightest change in dimension. The use of a microfluidic platform enables precise control of sub-100 nm organic nanoparticles (NPs) based on polybenzimidazole. Using hydrodynamic flow focusing, we can control the size and shape of the NPs, which in turn controls a number of particle material properties. The anhydrous proton-conducting nature of the prepared NPs allowed us to make a high-performance ion exchange membrane for fuel cell applications, and microfluidic tuning of the NPs allowed us subsequently to tune the fuel cell performance