Abstract: The carbon foams were prepared by carbonization of polyacrylonitrile membrane with carbon paper. After modified by CO₂, the BET specific surface area of the carbon foam increased from 14.3 to 290.2 m₂/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.

Key words: Conducting polymer, Thiophene derivative, Polyacrylonitrile membrane, Electrochemical capacitor