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Novel organic-inorganic composite polymer-electrolyte membranes for DMFCs

Sahu, AK and Bhat, SD and Pitchumani, S and Sridhar, P and Vimalan, V and George, C and Chandrakumar, N and Shukla, AK (2009) Novel organic-inorganic composite polymer-electrolyte membranes for DMFCs. In: Journal of Membrane Science, 345 (1-2). pp. 305-314.

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Organic-inorganic composite membranes comprising Nation with inorganic materials such as silica, mesoporous zirconium phosphate (MZP) and mesoporous titanium phosphate (MTP) are fabricated and evaluated as proton-exchange-membrane electrolytes for direct methanol fuel cells (DMFCs). For Nation-silica composite membrane, silica is impregnated into Nation matrix as a sol by a novel water hydrolysis process precluding the external use of an acid. Instead, the acidic nature of Nation facilitates in situ polymerization reaction with Nation leading to a uniform composite membrane. The rapid hydrolysis and polymerization reaction while preparing zirconia and titania sols leads to uncontrolled thickness and volume reduction in the composite membranes, and hence is not conducive for casting membranes. Nafion-MZP and Nafion-MTP composite membranes are prepared by mixing pre-formed porous MZP and MTP with Nation matrix. MZP and MTP are synthesised by co-assembly of a tri-block co-polymer, namely pluronic-F127, as a structure-directing agent, and a mixture of zirconium butoxide/titanium isopropoxide and phosphorous trichloride as inorganic precursors. Methanol release kinetics is studied by volume-localized NMR spectroscopy (employing ``point resolved spectroscopy'', PRESS), the results clearly demonstrating that the incorporation of inorganic fillers in Nation retards the methanol release kinetics under osmotic drag. Appreciable proton conductivity with reduced methanol permeability across the composite membranes leads to improved performance of DMFCs in relation to commercially available Nafion-117 membrane.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to Elsevier Science.
Keywords: DMFC;Methanol permeability;Nafion composites;NMR spectroscopy;Proton conductivity
Department/Centre: Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Depositing User: Id for Latest eprints
Date Deposited: 30 Nov 2009 06:03
Last Modified: 19 Sep 2010 05:52
URI: http://eprints.iisc.ac.in/id/eprint/25014

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