The Role of Aniline Adsorption on Carbon Fiber Before Plasma Treatment for Polyaniline Deposition

Polyaniline (Pani) is widely studied for power sources due to its easy synthesis, good chemical and thermal stabilities, high electrical conductivity and reversive oxidation/reduction processes. However, the interaction between Pani and the carbon substrate used as a current collector interferes with the efficiency of the final electrode. So, the present work aims at evaluating the effect of plasma functionalization of textile carbon fibers (CFs) with the intention of promoting conjugated covalent bonds between the substrate and the polymer chain, intensifying their interaction and electron transfer. The applied methodology is based on exposing CF to Ar/N₂ plasma to promote reactive groups on the surface and to create anchors to the growth of the polymer chain in the following interfacial synthesis of Pani. For comparison purposes, Pani electrodes are produced using CF with no treatment and CF with previously adsorbed aniline. The morphological characterization through scanning electron microscopy (SEM), allied with X-ray photoelectron spectroscopy (XPS), shows modifications in the fiber rugosity and the insertion of polar and N-functional groups on the surface. Finally, the electrochemical properties of the electrode are evaluated through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results show a lower impedance, a higher peak, and higher capacitive currents for the electrodes whose CF are treated by Ar/N₂ when compared with electrodes with untreated CF or with adsorbed aniline.