2000 Fiscal Year Final Research Report Summary
Peculiar reactions between interstitial compounds of transition metals and hydrogen peroxide and characterization of resultant materials
| Project/Area Number |
09450315
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
工業物理化学
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| Research Institution | University of Tokyo |
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Principal Investigator |
KUDO Tetsuichi Univ.of Tokyo, Inst.of Industrial Science, Professor, 生産技術研究所, 教授 (90205097)
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| Co-Investigator(Kenkyū-buntansha) |
HIBINO Mitsuhiro Univ.of Tokyo, Inst.of Industrial Science, Associate Professor, 生産技術研究所, 助教授 (20270910)
MIZUNO Noritaka Univ.of.Tokyo, Professor, 工学系研究科, 教授 (50181904)
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| Project Period (FY) |
1997 – 2000
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| Keywords | Tungsten carbide / Hydrogen peroxide / Proton conductivity / Nanohybrid materials / Malonic acid / Carboxylic acid / Dimethilmalonic acid / alchoxysillilate |
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| Research Abstract |
It has been found that some tungsten oxide clusters like peroxo-oxalato-polytungstate formed by a reaction of tungsten carbide with hydrogen peroxide show high proton conductivity. In this fiscal year have studied a methodology to incorporate such a cluster into an organic matrix to enhance chemical stability, and evaluated nanohybrid materials thus obtained as a proton conductive solid electrolyte membrane.
We obtained a homogeneous solution of a peroxotungstate complex by reacting tungsten trioxide monohydrate with hydrogen peroxide at 40℃ for 24 h. A carboxylic acid such as oxalic, malonic or dimethylmalonic acid was added to the solution at the ratio of 0.25-4.0 to tungsten atom, to yield a chelated complex. This solution was added to a methanol solution of alchoxysillilated poly (ethyleneoxide)-600 and polymerized at 60℃ by a sol-gel process. A homogeneous and transparent membrane was formed.
Proton conductivity of those membranes was measured in the temperature range of 25-160℃ under suturated water vapor pressure by the ac impedance method. Conductivity of a typical membrane at 80℃ was 1.4x10^<-2> Scm-1, which was 10 times higher that that of a composite membrane fabricated by simply blending PEO and tungsten trioxide dihydrate as an inorganic high proton conductor. This means that tungstate clusters dispersed at a nano-level homogeneity throughout the PEO-matrix form a percolation path for fast proton transport. Such a situation was also confirmed by vibration spectra and X-ray diffraction. Although conductivity fell with raising temperature above 100℃, it remained at a level of 10^<-4> Scm^<-1> in the range of 140-160℃. Bulky ligands such as dimethylmalonate tended to suppress conductivity fall at high temperature.
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