Comparative study on the supercapacitive properties of PANI nanofibers, nanotubes, and nanospheres

Abstract

In this study, polyaniline (PANI) nanostructures with different morphologies (nanofibers, nanotubes, and nanospheres) were obtained via interfacial polymerization, rapid mixing reaction, and hydrothermal method. The influences of the synthesis methods on the morphologies and supercapacitive properties of PANI nanostructures were investigated. The chemical structures of materials were characterized by Fourier-transform infrared and Raman spectroscopies. Scanning electron microscopy and transmission electron microscopy images were used to explore the morphologies of PANI nanostructures. N2 adsorption–desorption isotherm, cyclic voltammetry, charge–discharge test, and electrochemical impedance spectroscopy were used to characterize the pore distribution, electrochemical, and supercapacitive properties of PANI nanostructures. The results show that PANI nanotubes (PANI-T) exhibit the best electrochemical performances among three kinds of PANI nanostructures. The PANI-T exhibits high specific capacitances of 648 and 290 F g−1 at current densities of 0.5 and 10 A g−1, respectively, indicating its good supercapacitive property and rate capability. The enhanced electrochemical and supercapacitive performances can be attributed to its hollow nanotube structure.

Comparative Study of the Formation Mechanism of Polyaniline Nanorods and Nanotubes Through In Situ NMR Technique

“…Figure S1 showed in situ 1 H NMR spectra recorded the polymerization of aniline at the different concentration of SA. As seen in Figure S1 (supporting information), the change of the peaks of aniline and aniline dimer was similar at the early stage of polymerization, but the peaks of the oligomers with phenazine structure and water were observed to be different at later stage.…”

“…Nanostructured polyaniline (PANI) as an important kind of conducting polymers has been applied into various fields including sensors, absorbents, supercapacitors, and batteries, owing to the advantage such as low cost, simple preparation, the excellent environmental stability, its special doping/dedoping and controllable conductivity [1][2][3]. There are many important theories about the formation mechanism of nanostructured polyaniline, but it still cannot explain why the structure of fiber is only suitable for PANI but not for other conductive polymers [4][5][6][7][8][9].…”

“…Although these theories explain the formation mechanism of polyaniline nanotubes, they fail to explain the driving force of these spherical micelles to turn into rods or curl themselves on a molecular level. To solve the problem, in situ NMR technique is applied to study the nucleation mechanism of PANI, our team [15][16][17][18][19][20] have studied the nucleation mechanism of PANI nanosheets, nanofibers, nanotubes and hollow microspheres through in situ 1 H NMR and kinetic experiments including 1D NOE and T 1H , in combination with TEM, which indicates that the movement of water molecule including hydrated water can reflect the nucleation sensitively, in particular in the process of the structural transition. Meanwhile, it is found that PANI nanorods were synthesized at the low concentration of SA while PANI nanotubes were obtained at the high concentration of SA.…”

“…Meanwhile, it is found that PANI nanorods were synthesized at the low concentration of SA while PANI nanotubes were obtained at the high concentration of SA. Herein, on the basis of previous experimental technique such as in situ 1 H NMR technique and the FWHM (full width at half maxima) of anilinium, the new approaches including the integral area of aromatic region and the motion of water including bulk water and hydrated water were introduced to provide the kinetic information such as dipole interaction between species in the manuscript, and the formation mechanism of PANI nanorods was explained through comparing to that of PANI nanotubes.…”

Electrochemical fabrication of polyaniline/graphene paper (PANI/GP) supercapacitor electrode materials on free-standing flexible graphene paper

“…Therefore, the specific capacitance of the pseudocapacitor is higher than that of EDLC. 16 The electrode materials of pseudocapacitor mainly includes metal oxide and conductive polymer. 17 Conductive polymers are widely used because of their low cost, ease of synthesis, high conductivity and high specific capacitance.…”