Greetings bhaiya,

Definitely, application of constant current oxidizes the pyrrole monomer.. here are the steps involved according to the best of my knowledge

1. upon applying current (0.8-1.2mA) the electrons are withdrawn from the pyrrole monomer leading to the formation of radical cation (C4H5N.+)

As the reaction continues, the electrode potential shifts to more positive values to maintain the constant current (V/R=I) as can be seen in the graph.

2. the radical cations couple to form dimers, these dimers are further oxidized and more pyrrole units are added subsequently forming a polymer chain via chain growth polymerization (some Cl- ions are also incorporated in polymer matrix from the KCl solution increasing its conductivity)

3. these chains gets deposited on the anode since the oxidation process takes place on the electrode surface and the surface also provides nucleation sites for the polymerization process.

Role of electrolyte: anions from the electrolyte migrate to the electrode to counter the positive charge of the oxidized polymer.

However the solvent provides a medium for ion transport, heat dissipation to prevent damage to polymer film. Changing the solvent could lead to the following:

1. If the solvent is less effective at keeping the monomer dissolved, there might be premature precipitation of the monomer or oligomers, leading to inhomogeneous deposition.

2. A more polar solvent may stabilize the radical cations more effectively, potentially speeding up the polymerization. Conversely, a less polar solvent might slow the process down.

3. Solvents with different viscosities and dielectric constants can affect how the polymer nucleates and grows on the electrode surface. For example, a more viscous solvent might slow the diffusion of monomer and dopants, leading to a smoother, more uniform film, whereas a less viscous solvent might result in a rougher surface

Thank you, Abhinav. I forgot to mention it in the question but, if possible, please send me the links of the articles where the steps are explained. The working principle of CP itself hints at the PPy deposition but I had hard luck finding the literature report that suggested its electrodeposition in Pot. nitrate solvent. I need to cite that article.

Have you read these papers.

1. Liu, A., Li, C., Bai, H. & Shi, G. Electrochemical deposition of polypyrrole/sulfonated graphene composite films. J. Phys. Chem. C 114(51), 22783–22789 (2010).

2. Woo, T.-G., Park, I.-S. & Seol, K.-W. Effects of various metal seed layers on the surface morphology and structural composition of the electroplated copper layer. Metal. Mater. Int. 15(2), 293–297 (2009).

3. Alexandra, B., Marcu, M., Alexandrescu, E. & Anghel, E. M. "Electrochemical deposition and characterization of polyppyrrole coatings doped with nickel cobalt oxide for environmental applications. J. Solid State Electrochem. 18(10), 2661–2671 (2014).