Doped and de-doped polypyrrole nanowires by using a BMIMPF6 ionic liquid

We electrochemically synthesized π-conjugated polypyrrole (PPy) nanowires by using an environmentally stable and recyclable ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF₆), as a dopant, based on an anodic alumina oxide (Al₂O₃) nanoporous template. The de-doped states of the PPy nanowires were obtained from doped PPy nanowires through cyclic voltammetry (CV) using a solution of the catalyst in the BMIMPF₆ ionic liquid. We confirmed the de-doped states of PPy nanowires based on a decrease of the bipolaron peak of the ultraviolet and visible (UV–vis) absorbance spectra. The formation of PPy nanowires was visualized by using scanning electron microscopy and transmission electron microscopy. We studied the optical and structural properties of the doped and de-doped PPy nanowires by UV–vis absorbance and Fourier transform-infrared spectra. Our work included obtaining a laser confocal microscope Raman spectra for a single strand of the PPy nanowires.