Silver/Polyaniline Composite Nanotubes: One-Step Synthesis and Electrocatalytic Activity for Neurotransmitter Dopamine

Silver/polyaniline composite nanotubes have been successfully synthesized via a self-assembly process assisted by excess ammonium persulfate and silver nitrate as oxidant without using any acid molecule reagent or hard template, Scanning electron microscopy (SEM), energy-dispersive X-ray spectra (EDX), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), ultraviolet-visible absorption spectra (UV-vis), and X-ray photoelectron spectroscopy (XPS) were performed to characterize the resulting polyaniline samples. SEM and TEM images indicate that the as-obtained polyaniline composite entirely consists of uniform nanotubes in high yield with a diameter of about 100 nm. The TEM image shows that the average size of the dispersed silver nanoparticles decorated on the surface of the silver/polyaniline composite nanotubes is about 10 nm. A tentative mechanism is proposed in detail to elucidate the formation of the tubular nanostructures in such system. The composite nanotubes are immobilized on the surface of an indium tin oxide and applied to construct a sensor, which exhibits higher electrocatalytic activity toward reduction of dopamine than pure polyaniline. Furthermore, the high surface area, small diameter, and porous nature of the silver/polyaniline composite nanotubes and introduction of the silver nanoparticles give significantly better performance in both gas sensitivity and time response.