Interfacial characterization of poly(pyrrole) films doped with SiO2 nanoparticles and their use as electrosorptive phase of caffeine

Abstract

In this work we show the electrosynthesis of poly(pyrrole) films in the presence of SiO2 nanoparticles to develop a hybrid electrode to study the adsorption properties based on the electrochemical and interfacial features of the modified electrode. The electrodes were carefully characterized using electrochemical techniques such as voltammetry and electrochemical impedance spectroscopy, demonstrating that the inclusion of SiO2 nanoparticles in the PPy films has improved the electroactivity of the conducting polymer, in terms of both kinetics and mass transport. The morphology of the electrodes was also investigated by scanning electron microscopy, demonstrating the high surface achieved by the electrodeposition of either PPy and PPy/nano-SiO2. The system was studied for the electroadsorption of caffeine where the applied potential at the substrate plays a key role in tax of the adsorbed specie, mostly due to the increase of van der Waals interactions, enhanced greatly by the presence of the SiO2 nanoparticles. Adsorption isotherms and modeled equivalent circuits were also adopted to further characterize the interfacial properties of the different electrodes synthesized herein.