Carbon Microfibers Coated with 3-Methyl-4-Phenylpyrrole for Possible Uses in Energy Storage

This research examines the electrochemical polymerization of 3-Methyl-4-phenylpyrrole on carbon microfibers and compares its electrode performance with similar structures utilizing Poly-pyrrole and Poly-3-Phenylpyrrole on carbon microfibers. For technological considerations, going beyond a rate of 90 mV/s for the electrochemical deposition of the 3-Methyl-4-phenylpyrrole polymer is not advisable. By examining the Nyquist diagram, it is noted that the highest phase angle, exceeding 80°, occurs for the carbon–polymer structure created at a deposition rate of 70 mV/s, displaying the most pronounced capacitive behavior. Similar results at a deposition rate of 70 mV/s regarding SEM and AFM images were noted, revealing a structure that resembles the shape of the deposited polymer granules as “droplets” with a reduced average roughness level, at under 60 nm, and achieving a layer thickness of over 0.7 μm. Considering the results from cyclic voltammetry and electrochemical impedance, it was observed that the carbon micro-fiber structure coated with 3-Methyl-4-phenylpyrrole polymer shows superior capacitive behavior when compared to similar structures using pyrrole and 3-Phenyl-pyrrole polymers. 3-Methyl-4-phenylpyrrole also showed a lower admittance value than 3-Phenyl-pyrrole, and presented the highest capacitance, leading to a maximum increase of +27.3% in relation to pyrrole, emphasizing the significance of studying this PPy derivative for energy storage applications.