Fabrication of binary composites from polyaniline deposits on carbon fibers heat treated at three different temperatures: Structural and electrochemical analyses for potential application in supercapacitors

Abstract

Recent studies show that polyaniline (PAni) is one of the widely studied materials because it is easy synthesis, less cost, and low environmental pollution. Moreover, it presents a high theoretical specific capacitance as compared to carbon-based electrodes. Besides, when combined with materials such as porous carbon, graphene, carbon fiber, among others, the resulting electrodes composites present high electrochemical performance with feature commercially viable for practical application on supercapacitors. Carbon fibers (CF) heat-treated at three different temperatures of 1000, 1500, and 2000 °C worked as a template matrix as well as substrates coated with polyaniline (PAni) films, by chemical polymerization of the aniline, to obtain binary composites called PAni/CF-1000, PAni/CF-1500, and PAni/CF-2000, respectively. Composite morphology characterizations were done by scanning electron microscopy and showed that CFs were fully coated by PAni. Structural analyses by Raman spectra presented characteristic bands of the emeraldine salt, confirming that PAni is in its conductive form. The results of electrochemical measurements showed that all composites presented capacitive profiles and good reversibility. Particularly, PAni/CF-1000 showed the greatest PAni growth on CF surface not to mention its largest charge storage capacity, with specific capacitance at around 224 F g−1 and 98% of coulombic efficiency after 1000 cycles.