The Effect of Electrolyte Ingredients on Electrolyte-Electrode Interface in Electrocoating: A Comparative Study

Abstract

In this study, CFs were coated electrochemically with three different monomers (An, EDOT or Py) in different condition such as electrolyte (BA, H₂S0₄ or NaClO₄), solvent (H₂O as inorganic medium or ACN as organic medium), in presence of foreign material (EBC) and coating method (constant potential and cyclic voltammetry as controlled potential). Obtained CFs were compared with regard to electrical and capacitive and morphological features.

In CPE the current flown in system was changed in certain values for each monomer in presence of EBC. But this changing was more for Py than that for the other. In CV experiments, the oxidation potential was increased for PAn and PEDOT when it was decreased for Py. Imax values were changed for each polymer and conditions.

According to Randles-Sevcik equation, the electrocoating redox processes in BA-H₂O were not controlled by diffusion under this conditions.  But, all the redox processes carried out in NaClO₄-ACN electrolyte solution were controlled by diffusion for each polymer coated CFs. In presence of EBC it could be concluded that redox process was controlled by diffusion in BA-H₂O for PAn and in NaClO₄-ACN for PEDOT.

In presence of 1.8 % EBC. The C_DL value was decreased to 4 µF from 6 µF; to 0.7 µF from 1.5 µF; to 1 µF from 3 µF in BA-H₂O for Pan, PEDOT and PPy respectively. But, it was increased to 11.5 µF from 10.4 µF in NaClO₄-ACN for PEDOT. Phase angle was in the same trend.

The texture coatings were more compact in the presence of EBC in electrolyte solution than that of the absence of EBC for PPy coated CF. The relationship of between the radius of coating and the C_DL of the coated CF was proportional. Thus, it may be concluded that the C_DL and radius of coating were affected with the presence of different material/compound in electrolyte solution.

Keywords: PAn, PEDOT, PPy, presence of EBC, comparison, impedance, texture coating.

DOI: 10.7176/CMR/13-3-05

Publication date:November 30^th 2021