Study on Application of Fluorine Materials

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The following results have been obtained from the cooperative study on the synthesis and applications of fluorine compounds.1.Electrochemical property of qraphite compoundsGraphite intercalation compounds of vanadium fluoride have been synthesized from natural graphite powder in a fluorine atmosphere. The compounds obtained were stage 2 C_<22>VF_6 - C_<17>VF_6 and stage 1 C_<12>VF_6 - C_<10>VF_6. The electrochemical property of these compounds were examined in propylene carbonate - 1 M LiClO_4 solution with Li anode. Three reduction peaks were observed in the current -potential curves. Two peaks at -0.15 and -1.50 V were common in all the samples, however, the third peak was shifted from +0.10 to -0.9 V with decreasing concentration of intercalated vanadium fluoride and coexisting fluorine. Electrochemical reduction of C_xF has revealed that the reduction peak is shifted to the negative potential with decreasing fluorine content. Furthermore the reduction peak for VF_3 was observed at … More -1.3 V. These results suggest the electrochemical reduction of VF_5 and fluorine.2.Synthesis of highly fluorinated graphiteHighly fluorinated graphite has been synthesized in anhydrous liquid HF containing a small amount of MoF_6 or SbF_5 as an oxidizer of natural graphite powder. The obtained compounds were stage 1 C_<2.0>F - C_<2.4>F. The lattice parameter a_0 was increased from 2.462 A of graphite host to 2.467 - 2.473 a, and c-axis repeat distance was in the range of 10.7 to 12.0 A. The large c-axis repeat distance means that ionically bonded fluorine atoms and covalently bonded ones are inserted in every other carbon layer, forming a bi-intercalation phase. XPS and IR spectroscopy have indicated the existence of C-F covalent bonds.3.Surface free energy and electrochemical application of graphite compoundsSurface properties of fluorine-graphite compounds vary depending on the nature of carbonfluorine bonds. Contact angle measurement has revealed that the surface free energy of C_xF is close to that of graphite itself, however, the polar component of C_xF is much larger than that of graphite. This means that C_xF has higher wettability than graphite. On the other hand, the surface free energy of graphite fluoride with covalent bond is much smaller than those of C_xF and graphite. The hydrophobic nature has been applied to the new hydrophobic nickel electrode for electrofluorination of organic compounds.4.Structure and electrochemical property of heteroatom compoundsThe redox reactions of Se<@D12+@>D1 (] SY.dblharw.[) Se and Te<@D12+@>D1 (] SY.dblharw.[) Te have been found. Less