Influence of heat treatment temperature of carbon fiber felt substrate on polyaniline electrosynthesis and its properties

摘要

Polyaniline was electrosynthesized using three voltammetric cycles on carbon fiber felts annealed at 1400, 1600, 2000, and 2300K. Felts and composites was characterized by scanning electron microscopy, X-ray diffraction, Raman and Fourier transform infrared spectroscopy, and electrochemical impedance spectroscopy. Annealing temperatures increasing provides more crystalline felts. The increase of capacitance is due to presence of functional groups that attract a lot of charge to double layer. Capacitance found for felts treated in 1400K is larger compared to felts treated in 2300K. The functional groups presence on annealed felts at lower temperature implies polyaniline growth in several orientations and regions, evidenced by the high heteroatoms ratios which decrease with increasing annealing temperature. Therefore, for higher temperatures, the polyaniline growth occurs at several additional orientations. The polyaniline oxidation degree was close to emeraldine allowing mobile charge presence. Electrochemical impedance spectroscopy confirmed that as temperature decreases, resistance of inner and outer double layer decreases. To 1600K annealing, polyaniline showed an increase in inner double layer capacitance which can be confirmed by lower ratio between bipolarons and polarons. The tendency to increase energy and power density is most prominent for polyaniline at 2300K felt.