Effects of frequency on supercapacitor properties of multi walled carbon nanotubes-polypyrrole film prepared by alternating current-electrophoretic deposition method

An electroactive supercapacitor electrodes have been prepared through deposition of multi walled carbon nanotubes-polypyrrole (MWCNTs-PPy) via alternating current electrophoretic deposition method (AC-EPD). Using safranin (SAF) as co-dispersant, a stable and well-dispersed MWCNTs were obtained and the deposits of MWCNTs-PPy were successfully formed using AC peak to peak voltage of 8 V but at difference frequencies of 0.01 Hz, 4 Hz and 250 Hz. Varying the frequencies of the applied voltage has been found influencing the morphology and electrochemical properties of the deposited films. A more porous and highest deposited mass of 0.021 g was obtained at frequency of 4 Hz, while at 250 Hz the deposited mass reduces to 0.017 g. The lowest deposited mass of 0.015 g was obtained at the lowest frequency (0.01 Hz). In addition, the morphology structure of the composite film at 4 Hz shows that the PPy were well-distributed throughout MWCNTs surface. The XRD result shows the presence of amorphous PPy and graphite-like MWCNTs for all deposited samples. It has been shown that the specific capacitance values for the composites also strongly depends on the frequency of applied voltage. In the case of frequency of 4 Hz, higher values can be found at 76.08 F g(-1) which was more than two folds increment from the lowest frequency (0.01 Hz), however at the highest frequency (250 Hz) a specific capacitance values of 65.03 F g(-1) have been measured. The AC-EPD provides avenue for depositing nanocomposites film at relatively low apllied voltage however, there have no linear correllations been observed on the morphology and electrochemical properties of the deposited films as the frequencies of applied voltage increases.