Synthesis, Characterization, and Electrochemistry of Nanotubular Polypyrrole and Polypyrrole-Derived Carbon Nanotubes

Abstract

Polypyrrole nanotubes (PPy-NTs) were prepared by the oxidation of pyrrole with iron(III) chloride in the presence of a structure-guiding agent, methyl orange. Upon carbonization of the salt form of PPy-NTs, the conducting nitrogencontaining nanotubular carbonaceous material (C-PPy-NT) was obtained. The morphology, structure, and physicochemical properties of PPy-NTs in salt and base form as well as C-PPy-NTs were investigated by transmission electron microscopy, Fourier transform infrared and Raman spectroscopies, conductivity measurements, elemental microanalysis, inductively coupled plasma optical emission spectroscopy, Xray photoelectron spectroscopy, and nitrogen physisorption. Results of the material characterization were linked to their electrochemical behavior. Specific capacitance of around 120 F g −1 at low potential sweep rate of 5 mV s −1 was observed for original PPy-NTs. However, when the potential sweep rate was increased to 100 mV s −1 , PPy-NT salt retained the value of specific capacitance, while the capacitance of PPy-NT base decreased by 70%. Upon carbonization of PPy-NT salt, the specific capacitance was doubled and capacitance fade measured in the interval 5−100 mV s −1 was determined to be around 45%. It is proposed that the absolute value of specific capacitance is determined by specific surface area and surface functional groups, while the capacitance fade is determined by the conductivity of the electrode material. In this manner, a linear relationship between the percent of capacitance fade and the logarithm of the conductivity was revealed. C-PPy-NTs were also tested as an electrocatalyst for the oxygen reduction reaction (ORR) in alkaline media. High ORR activity was observed, characterized by the onset potential of −0.1 V versus saturated calomel electrode and the apparent number of electrons consumed per oxygen molecule higher than 3. Appreciable ORR activity can be linked with a high fraction of mesopores and the presence of surface functional groups, especially pyridinic and pyrrolic nitrogens, and also with a high degree of structural disorder.

The composites of silver with globular or nanotubular polypyrrole: The control of silver content

“…The maxima of the bands are observed at 1609, 1545, 1395, 1322 (with a shoulder at 1242 cm À1 ) and at 1041, and 921 cm À1 (with a shoulder at 875 cm À1 ). As in case of the infrared spectra they are very close to each other for different composition of oxidant mixture and also to the spectrum of deprotonated nanotubular PPy prepared by oxidation with iron(III) chloride hexahydrate [49]. In optical images of the nanotubular PPy/silver composites we have also observed some red crystals.…”

“…The maxima of the bands are observed at 1560 (with a shoulder at 1600 cm À1 ), at 1467, 1358, 1298, 1169 (with a shoulder at 1104 cm À1 ), and at 1028, 903 and 770 cm À1 . They are very close to each other for different composition of oxidant mixture and also to the spectrum of deprotonated nanotubular PPy prepared by oxidation with iron (III) chloride hexahydrate [49].…”

Porous and high electronic conductivity nitrogen-doped nano-sheet carbon derived from polypyrrole for high-power supercapacitors

“…To enhance the rate performance and power capability, doping of heteroatoms (such as nitrogen [30][31][32], sulfur [33], or boron [34]) into carbon frameworks is a vital candidate. Recent research indicates that nitrogen doping seems to be the most promising method for enhancing capacitance while keeping the superb cycling stability of carbon material.…”

Strategies towards the control of one‐dimensional polypyrrole nanomorphology and conductivity

“…The conversion of a globular morphology to nanotubes stimulated by methyl orange has been well established in the literature (Fig. ).…”