Electrochemical synthesis and characterization of self-supported polypyrrole-DBS-MWCNT electrodes

Abstract

The electrochemical conditions (electrolyte potential window, monomeric oxidation) for the synthesis of polypyrrole-dodecylbenzenesulfonate-multiwalled carbon nanotube (PPy-DBS-MWCNT) composite were determined. Thick PPy-DBS-MWNT films were electrogenerated and peeled off from the working electrode. Self-supported PPy-DBS-MWCNT electrodes were fabricated. The morphology of the film was analyzed by SEM. Self-supported electrodes were characterized by potential cycling and by consecutive square potential waves in NaClO4 aqueous solution with different cathodic potential limits. Higher reduced structures (the current never drops to zero) are obtained and analyzed from voltammetric responses until rising cathodic potential limits (up to −5V). For high cathodic potentials (>−1V) a slow hydrogen evolution coexists with the film reduction, as revealed from coulovoltammetric (charge-potential) responses, and the reduction rate decreases without significant polymeric degradation. Degradation of the material electroactivity in NaClO4 is initiated by anodic overpotentials beyond 1.2V. Both, oxidation and reduction chronoamperometric responses prove the presence of nucleation processes, most significant during oxidation. Chronocoulometric responses illustrate slower oxidation rates from deeper reduced initial states. The electrochemical responses are explained by reaction-driven conformational and structural changes that are clarified by the coulovoltammetric responses.