Self-Supported Polypyrrole/Polyvinylsulfate Films: Electrochemical Synthesis, Characterization, and Sensing Properties of Their Redox Reactions

Thick films of polypyrrole/polyvinylsulfate (PPy/PVS) blends were electrogenerated on stainless-steel electrodes under potentiostatic conditions from aqueous solution. The best electropolymerization potential window was determined by cyclic voltammetry. After removing the film from the back metal, self-supported electrodes were obtained. Voltammetric, coulovoltammetric, and chronoamperometric responses from a LiClO4 aqueous solution indicated the formation of an energetically stable structure beyond a reduction threshold of the material. Its subsequent oxidation required higher anodic voltammetric overpotentials or longer chronoamperometric oxi-dation times. This structure was attributed to the formation of lamellar or vacuolar structures. X-ray photoelectron spectroscopy analysis of the films under different oxidations states revealed that the electrochemical reactions drive the reversible exchange of cations between the film and the electrolyte. The electrical energy and the charge consumed by the reversible reaction of the film under voltammetric conditions between the constant potential limits are a function of the potential scan rate, that is, they sense the working electrochemical conditions.