Electrochemical growth of polypyrrole microcontainers

Polypyrrole microcontainers with morphology like bowls, cups, and bottles have been electrochemically generated by direct oxidation of pyrrole in the aqueous solution of P-naphthalenesulfonic acid (beta-NSA). The well-ordered microcontainers stand upright on the working electrode surface in a density of 2000-8000 units cm(-2). Their morphological features can be simply controlled by electrochemical polymerization condition, and the results have a good reproducibility. The growth process of microcontainers was studied by scanning electron microscopy. A "soup bubble" growth mechanism was postulated and confirmed by electrolysis of water using a polypyrrole film-coated electrode. The walls of the microcontainers were made of polypyrrole in the oxidized (conductive) state according to the results of Raman and infrared spectroscopies. Electrochemical studies demonstrated that the PPy film with microcontainers had a large surface area which resulted in high film/electrolyte double-layer capacitive charges.