Molecular design of layered zirconium phosphonates for fuel cell applications

Segawa, Kohichi; Funamoto, Takako; Ando, Jumpei; Yamaguchi, Chiharu; Kaneko, Keiichi; Takeoka, Yuko; Rikukawa, Masahiro

doi:10.1016/s0167-2991(04)80929-7

Cited by 3 publications

(3 citation statements)

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“…Though of initially promising performance, dopant leaching reduced polyelectrolyte conductivity and contaminated the noble metal electrode surfaces 49. To improve performance at elevated temperatures, hydration retentive and barrier forming fillers, such as sol‐gel deposited silica,50 and inherently proton conductive, high aspect zirconium phosphates and phosphonates have seen thorough investigation 51–59. Though some such composites showed promising conductivities at up to 120 °C,60 this was usually accompanied by greatly increased water uptake.…”

Section: Introductionmentioning

confidence: 99%

“…When applied to blends, zirconation gave far more advantageous effects: a zirconated blend membrane containing 5 wt.‐% phoH‐PSU‐102 exhibited a negligible area swelling of 2 A‐% at 80 °C and a high proton conductivity of 40 mS · cm −1 at 25 °C. The treatment of cation‐exchanging polyelectrolytes with an aqueous ZrOCl 2 solution is taken to induce ionic crosslinking by formation of Zr IV ‐phosphonates, previously investigated as solid acid proton conductors 53–59. The very low dissociation constant of Zr‐phosphonates explains the ionomers' stability against area swelling and their greatly reduced water uptake.…”

Section: Introductionmentioning

confidence: 99%

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Arylphosphonic Acid‐Functionalized Polyelectrolytes as Fuel Cell Membrane Material

Bock

Möhwald

Mülhaupt

2007

Macro Chemistry & Physics

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IntroductionThe growing awareness of diminishing fossil fuel reserves and man-made climate change has encouraged academic and industrial research into more efficient use of primary energy sources. Regarding efficiency in power generation, the single-step energy conversion in fuel cells (FC) is inherently superior to the multi-step internal combustion engine.[1] Fuel cells, like other electro-chemical energy devices, provide an electric current by physical detachment of a redox reaction into an oxidation and a reduction part, and separation of the resultant electron and ion flux using an ion-conductive solid electrolyte. To preserve over-all cell neutrality, the electrolyte has to facilitate an ion transport antagonistic to the electron movement. In the operant hydrogen-or methanol-powered fuel cell, the charge imbalance that results from electron transport is compensated by a cathode-wise proton transport via a proton conductive polyelectrolyte membrane (PEM) material. A fuel cell's power output is, therefore, coupled to the ReviewIn comparison to sulfonated polymers, phosphonic acid-functionalized polyelectrolytes possess higher proton conductivity at elevated temperatures, improved chemical and thermal stabilities, much lower water swelling, decreased fuel permeability, and enhanced proton conductivities in low hydration states. Arylphosphonic acid-functionalized polymers have been produced by the copolymerization of arylphosphonated monomers, as well as by various polymer-analogous functionalization reactions on high performance polymer backbones. Among the latter, the catalytic arylphosphonation of brominated high-performance polymers, such as poly(ethers), poly(sulfones), and poly(etherketones) represents an attractive and versatile synthetic route to arylphosphonic polyelectrolytes for application in polyelectrolyte membrane fuel cells (PEMFC). This review summarizes available syntheses of arylphosphonic acid-functionalized polymers, the data on such materials' membrane performance, and introduces special polyelectrolyte blends and new ionomers developed to meet the demands made on PEMFC membranes. electrolyte's proton conductivity under operating conditions, which explains the on-going effort to establish materials with suitable properties. Among the presently discussed fuel-cell types, [1] the polyelectrolyte membrane fuel cell (PEMFC) and the direct methanol fuel cell (DMFC) are considered best suited for portable and mobile applications, because of their high power densities, moderate operating temperatures of 60-120 8C, and accordingly short start-up times. The polyelectrolyte fuel cell scheme displayed in Figure 1 shows the PEMFC to basically resemble a 'gas battery', which derives an electric current from the catalytic oxidation of hydrogen on noble metal electrodes, e.g., Pt or Pt-Ru alloys. However, available PEMs' material properties limits fuel-cell operation to temperatures below 80 8C. Since noble metal electrodes' are prone to deactivation by fuelcontaminating trace CO below 120 8C, [2,3] pres...

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Arylphosphonic Acid‐Functionalized Polyelectrolytes as Fuel Cell Membrane Material

Bock

Möhwald

Mülhaupt

2007

Macro Chemistry & Physics

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“…During the reaction, both methylphosphonic acid and phosphoric acid molecules were randomly incorporated into the layers, forming a layered structure with methyl and hydroxyl groups pointing to the interlayer space. The detailed chemistry regarding the synthesis of α-ZrP derivatives can be found elsewhere − and is schematically illustrated in Figure . α-ZrP was also synthesized via a similar hydrothermal approach and used as a control. , The formulations and reaction conditions for the synthesis of the above α-ZrP derivatives are summarized in Table .…”

Section: Methodsmentioning

confidence: 99%

Polypropylene Nanocomposites Based on Designed Synthetic Nanoplatelets

et al. 2009

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Synthetic nanoplatelets derived from α-zirconium phosphate (α-ZrP) were prepared for in situ propylene polymerization, yielding polypropylene (PP) nanocomposites. The designed α-ZrP-derivatives contain methyl groups on the surface to increase hydrophobicity, which gives rise to a better compatibility with toluene and propylene molecules. The incorporation of methyl groups on the layers of α-ZrP-derivatives also produces a “porous pathway” structure in the nanoplatelet gallery, which facilitates the diffusion of propylene monomers. PP/α-ZrP nanocomposites were successfully prepared with a high level of exfoliation. The implications of the present findings are discussed.

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