Synthesis and characterization of nanostructured polypyrroles: Morphology-dependent electrochemical responses and chemical deposition of Au nanoparticles

We report here the preparation of nanostructured polypyrroles (PPys) with different morphologies (nanospherical or nanofibrillar) through a surfactant-assisted oxidative polymerization route. Nano-fibrillar PPy has a higher redox current, presumably due to a higher surface area accessible to the electrolytes and a lower charge transfer resistance compared to that of the spherical PPy. The impedance spectrum of spherical PPy at lower frequencies suggests a semi-infinite diffusion process, while nanofibrillar PPy displays barrier diffusion and capacitor characteristics. Electrodeless (chemical) deposition of Au particles from AuCl aqueous solution using namostructured PPy also shows different morphologies, presumably due to a difference in growth kinetics dominated by the differences in surface area and surface chemistry. Our work demonstrates control over the electrochemical responses and charge transfer mechanisms of these conducting polymers. This control arises from their unique length scale geometries and surface areas that allows for the fabrication of Au nanoparticles with tunable morphologies. Our work in the controlled synthesis of nanostructured conducting polymers and metal nanoparticles opens up new opportunities for nanofiber-based electronic and sensory devices. (C) 2009 Elsevier Ltd. All rights reserved.