The carbon foams were prepared by carbonization of polyacrylonitrile membrane with carbon paper. After modified by CO 2, the BET specific surface area of the carbon foam increased from 14.3 to 290.2 m 2/g and there are more electrical double layer capacitance than that in the unmodified carbon foams. Composite electrodes were fabricated by electrochemical polymerization of 3-(4-fluorophenyl)thiophene on carbon foams in 0.2 mol/L tetraethylammonium tetrafluoroborate in acetonitrile solution. Cyclic voltammetry of PFPT/carbon foam electrodes show that they have two type of capacitance: one is quasicapacitance originated from PFPT doping/undoping in electrolyte solution; the other is electrical double layer capacitance belonging to high specific area of the composite electrodes. The performance of electrochemical capacitors, such as energy density, would be improved by adopting this carbon foam with a high specific area as electrodes in polymerization of conducting polymers.
Porous membranes of polyacry lonitrile were prepared directly on carbon paper with the phase inversion method,and then cross-linked under γ-ray radiation.Carbon foam materials were obtained from these cross-linked composite porous membranes after oxidation at 220℃ in air,carbonization at 850℃ in nitrogen and activation at 850℃ in CO-2.Morphologies of the carbon foam materials were observed with scanning electron microscopy,and the specific surface area was measured with the Brunauer-Emmett-Teller(BET) technique.It was found that the network structure of the carbon foam materials was affected by γ-ray radiation,and that the BET value could reach a high value of 500 m+2/g after treatment with CO-2 at 850℃.These carbon foam materials can be used directly as electrodes of electrochemical capacitors in suitable shapes and size.Cyclic voltammetry,AC impedance spectrum and galvanic cycles of the carbon foam electrode were tested both in aqueous and organic media for evaluating its electrochemical performance.The results show that the specific capacitance of such a carbon foam electrode in 1 mol/L aqueous solution of sulfuric acid is 174 F/g,which is at the high level of carbon electrodes.
Polyaniline/fractionized carbon nanotube composite was prepared with the polymerization of aniline in the FCNTs dispersed liquid. The SEM micrographs indicate that carbon nanotubes are coated with polyaniline; the thickness of the polyaniline on carbon nanotubes is about 5～10 nm; and carbon nanotubes were dispersed well in the composite on the nanometer scale. The apparent density and the electrical conductivity of the polyaniline/fractionized carbon nanotube composite are 440 kg/m+3 and 173 S/m, respectively. As compared with polyaniline, the apparent density and the conductivity of the composite increased by about 82% and 1400%, respectively. TGA tests indicate that the composite has better thermal-stability than that of polyaniline.
