In this study, protonic acid and iodine-doped conductive polyaniline (PANI) nanofibers were successfully fabricated in one step using ammonium persulfate (APS) and potassium biiodate (KH(IO3)2) as the co-oxidant. The resultant PANI nanofibers were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, wide-angle X-ray diffraction, and X-ray photoelectron spectroscopy. Their electrochemical properties were examined by cyclic voltammetry and the standard four-probe technique. Additionally, the molecular weight of the conductive PANI nanofibers was measured using a viscometer. It is found that the PANI nanofibers are codoped with protonic acid (hydrochloric acid and iodic acid) and iodine (I3− and I5−), and the KH(IO3)2 shows a significant acceleration effect for the oxidation polymerization of aniline. The conductivity of PANI reaches 21 S·cm−1, which is much higher than that of another PANI prepared by APS. This is ascribed to the iodine-doping effect and the nanofibers’ morphology. Additionally, the reaction mechanism of PANI is systematically discussed, and the codoped mechanism is proposed. Systematic investigations indicate that APS/KH(IO3)2 is an excellent co-oxidant for the preparation of highly conductive PANI nanofibers in one step.
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