Electrocatalytic And Pseudocapacitive Properties Of Polyaniline Based Composite Film

Conducting polymer based organic-inorganic composite materials have attracted considerable attentions in recent years. They can not only combine the advantages of the components but also exhibit synergistic effect through organic-inorganic interactions. Polyaniline (PANI) is a promising material owing to its low cost, ease of fabrication and good chemical stability. However, PANI usually loses its electroactivities at pH above 4, which restricts its applications. Combination of PANI with inorganic materials, can not only remedy the deficit of PANI, but also can strengthen the property of the inorganic moieties. Thus composite materials of PANI and inorganic compounds deserve investigation in both theoretic and application researches.In this work, PANI was composited with inorganic materials such as MoOx and functional carbon. By the finely distribution of MoOx in PANI matrix, the organic-inorganic composite with high electrochemical activity and good pseudocapacitive properties was fabricated through the synergistic effect of the organic and the inorganic moieties. The -SO3H groups were introduced onto molecular chains of PANI to form self-doped PANI, SPAN, which can improve its electroactivity in neutral solution. This dissertation is focused on the following points:1. MoOx/PANI composite modified carbon cloth was fabricated by cyclic voltammetry (CV) from a solution of aniline and (NH4)6Mo7O24. The MoOx/PANI composite was characterized by X-ray photoelectron (XPS), Fourier transform infrared spectroscopy (FTIR) and CV. The obtained MoOx/PANI film displayed a significant enhancement of electrocatalytic activity for chlorate reduction and a better stability than MoOx due to the synergistic effect of the two components and the uniform distribution of MoOx in PANI. Result of amperometric experiment revealed a good linear relationship between response current of the modified electrode and concentration of ClO3- from 5μM to 10 mM, with a high sensitivity of 21.59 mA/mM and a detection limit of 1.3μM for the determination of C1O3-.2. Functional carbon (FC) was obtained by CV in H2SO4 solution. The functional group was characterized by XPS and FTIR. The surface roughness of the functional carbon was investigated by confocal laser scanning microscope. The degree of functionalization and surface roughness of FC-2M is more than that of FC-05M, which were obtained by treatment in solutions of 2 M and 0.5 M H2SO4, respectively. The specific capacitance of the functional carbon is larger than that of the untreated carbon, due to the larger electric double layer capacitance and pseudocapacitance arised from Faradic reactions of the functional groups as well.3. Self-doped polyaniline, SPAN was obtained on FC through electrocopolymerization of aniline with metalic acid by constant potential. The introduced-SO3H group can dope with N atom of=N-, thus the conductivity of SPAN is independent on acidity of the solution in a broad pH range. The obtained SPAN/FC displayed a specific capacitance of 408 F-g-1 in the potential range of-0.6 ～0.6 V, in 0.5 M Na2SO4 solution.4. MoOx/SPAN composite was deposited on FC by constant potential. The obtained MoOx/SPAN/FC composite electrode exhibited good pseudocapacitive performance over a wide potential range of-0.6 to 0.8 V vs. SCE. An symmetric model capacitor using MoOx/SPAN/FC as both negative and positive electrodes displayed a specific capacitance of 105 F-g-1 over a voltage range of 1.4 V, with an energy density of 1 kW-kg-1 at the power density of 28.7 Wh-kg-1.