Study on horn-shaped polypyrrole prepared by pulse potential

• We presented a simple and stable synthesis process for horn-shaped polypyrrole (PPy) with micro/nanometer structure.
• The detailed growth mechanism of horn-shaped PPy was suggested and explained.
• The horn-shaped PPy films showed high specific capacitance especially at high scanning rate.
• The capacitance of horn-shaped PPy films decreased by only 2% after 10,000 cycles.

Polypyrrole (PPy) films were prepared by direct current (DC), pulse current (PC) and pulse potential (PP) in aqueous solutions. The scanning electron microscope (SEM) images of PPy films indicated that a lot of horn-shaped PPy was formed during PP-PPy polymerization process. The top-end of horn-shaped PPy exhibits both open and closed structures. The body of horn-shaped PPy has a hollow structure with a thin wall. The micelles composed by PPy monomer and p-toluenesulfonate anions (PTS−) was formed when pyrrole monomer was dispersed in aqueous solution containing PTS− anions by mechanical stirring. In PP polymerization, the micelles with negative charge were repelled and hence left the surface of PPy films at switch off time. As a result, the PTS− anions on the surface of micelles were effectively supplied, and thus stabilized the micelles. This process results in the continuous growth of horn-shaped PPy. The hollow horn-shaped PPy films showed big specific capacitance, high charging/discharging rate and better stability.

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