Electrical conductivity, ionic conductivity, optical absorption, and gas separation properties of ionically conductive polymer membranes embedded with Si microwire arrays

Joshua M. Spurgeon, Michael G. Walter, Junfeng Zhou, Paul A. Kohl, Nathan S Lewis

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The optical absorption, ionic conductivity, electronic conductivity, and gas separation properties have been evaluated for flexible composite films of ionically conductive polymers that contain partially embedded arrays of ordered, crystalline, p-type Si microwires. The cation exchange ionomer Nafion, and a recently developed anion exchange ionomer, poly(arylene ether sulfone) that contains quaternary ammonium groups (QAPSF), produced composite microwire array/ionomer membrane films that were suitable for operation in acidic or alkaline media, respectively. The ionic conductivity of the Si wire array/Nafion composite films in 2.0M H2SO4(aq) was 71 mS cm-1, and the conductivity of the Si wire array/QAPSF composite films in 2.0M KOH(aq) was 6.4 mS cm-1. Both values were comparable to the conductivities observed for films of these ionomers that did not contain embedded Si wire arrays. Two Si wire array/Nafion membranes were electrically connected in series, using a conducting polymer, to produce a trilayer, multifunctional membrane that exhibited an ionic conductivity in 2.0MH2SO4(aq) of 57 mS cm-1 and an ohmic electrical contact, with an areal resistance of ∼0.30 Ω cm2, between the two physically separate embedded Si wire arrays. All of the wire array/ionomer composite membranes showed low rates of hydrogen crossover. Optical measurements indicated very low absorption (

Original languageEnglish
Pages (from-to)1772-1780
Number of pages9
JournalEnergy and Environmental Science
Issue number5
Publication statusPublished - May 2011


ASJC Scopus subject areas

  • Nuclear Energy and Engineering
  • Renewable Energy, Sustainability and the Environment
  • Environmental Chemistry
  • Pollution

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