The role of plasma pretreatments on carbon fiber substrates for polyaniline thin film deposition

Abstract Carbon fiber cloth was functionalized in N 2 /Ar pulsed plasma, aiming to improve the interaction between the carbon fibers (CFs) and polyaniline (PANI) films. The PANI films were deposited onto the CF substrate by means of an electrochemical process. Plasma treatment was performed using a cathode cage setup, with the CF samples kept at floating potential inside the cage. Two types of CF substrates were subjected to plasma treatment: 1- raw samples; 2- samples with aniline vapor adsorbed onto their surfaces (CF samples previously subjected to aniline vapor in a vapor chamber). The effect of the plasma treatment prior to the PANI deposition was investigated on the anodic peak and the anodic charge accumulation measured by cyclic voltammetry, and on the double layer capacitance and charge transfer resistance measured by electrochemical impedance spectroscopy. The best results were observed for CF samples with aniline vapors adsorbed on their surface prior to the pulsed plasma treatment at 100 kHz. PANI electrodes constructed using this substrate showed an improvement of 36% in peak current density and 50% in anodic charge accumulation as a consequence of higher double-layer capacitance and faradaic pseudocapacitance, along with a reduction in resistances related to charge transfer and ionic diffusion.