Nucleation, growth and branching of polyaniline from microelectrode experiments

Bade, K.; Tsakova, V.; Schultze, J.W.

doi:10.1016/0013-4686(92)85120-a

Cited by 162 publications

(92 citation statements)

References 16 publications

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“…On the other hand, for PANI, the current transients are linear with time for 600 s followed by an exponential growth (1D needle type growth). The nucleation and growth of polyaniline is in agreement with other reported work [35]. EQCM studies on polymer films of different polymerization charges (8, 21, 32 mC cm (2 ) were carried out and the total mass of the polymer deposited was calculated by using the Sauerbrey equation for the resonance frequency of the quartz crystal [36].…”

Section: Effect Of Sds On Electrochemical Polymerizationsupporting

confidence: 88%

Studies on electropolymerization of aniline in the presence of sodium dodecyl sulfate and its application in sensing urea

Kanungo

Kumar

Contractor

2002

Journal of Electroanalytical Chemistry

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Section: Effect Of Sds On Electrochemical Polymerizationsupporting

confidence: 88%

Studies on electropolymerization of aniline in the presence of sodium dodecyl sulfate and its application in sensing urea

Kanungo

Kumar

Contractor

2002

Journal of Electroanalytical Chemistry

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“…This enhanced current is considered to result from the autocatalytic oxidation of aniline, in which monomer aniline is oxidized by the fully oxidized PAn to generate its radical cation. 5,16 The upward peak observed at 1500 cm -1 (Fig. 3b) indicates a decrease in the concentration of aniline.…”

Section: Polymerization In H 2 So 4 Solutionmentioning

confidence: 98%

In Situ Observation of Electrochemical Formation and Degradation Processes of Polyaniline by Fourier-Transform Infrared Spectroscopy

1999

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Polyaniline (PAn) is an electrically conducting polymer that can be easily prepared by the chemical and electrochemical oxidation of aniline, and shows excellent stability under ambient conditions. Electrochemical synthesis is generally carried out on metal electrodes in aqueous acidic solutions, such as HClO 4 , HCl and H 2 SO 4 , using potentiostatic, galvanostatic and potential cycling methods. A large number of studies on the redox process of PAn have been performed by means of electrochemical and optical techniques, revealing that electron transfer causes the migration of electrolyte ions into or out of the polymer film. 1 However, the scheme of electropolymerization of aniline, involving the charge-compensation manner, is not well understood. A film prepared from HClO 4 is known to be denser than that from H 2 SO 4 , suggesting that the electrolyte anion plays an important role in the polymerization of aniline. 2,3 According to the reaction scheme proposed by Mohilner et al., polymerization starts by the oxidation of non-protonated aniline to radical cationic species, and proceeds through coupling with another radical; these reactions are accompanied by the release of protons to eliminate the generated positive charges. 4 This suggests that the acidity at the polymer/solution interface increases during the course of aniline oxidation, but the effect of accumulated protons on the rate of polymerization is not determined. Furthermore, side reactions, such as degradation of the polymer, are not negligible during prolonged polymerization. 5 An in situ spectroelectrochemical method is useful to study such unclear problems.In the present study, in situ FTIR spectroscopy was applied to the electrochemical polymerization of aniline, and the growing polymer and polymer/solution interface were investigated on the molecular level. In situ FTIR spectroscopy has proven to be fruitful for studies on the metal/solution interface 6 and an electroactive film.7 An advantage of this technique when used in the latter system is that it allows a simultaneous determination of the polymer structure and movement of electrolyte species through the film. ExperimentalAll chemicals were of reagent grade and used as received. Sulfuric and perchloric acid solutions used as the electrolytes were prepared with those chemicals and doubly distilled water, and higher pH values were adjusted by adding a concentrated NaOH solution.The FTIR spectrometer used was a Shimadzu FTIR 8100M equipped with an external-reflection unit and a HgCdTe (MCT) detector cooled with liquid nitrogen. The spectroelectrochemical cell was similar to that described elsewhere. 8 A flat CaF 2 disk was used as the IR transparent window, and the angle of incidence on the CaF 2 surface was 70˚. Spectroelectrochemical experiments were carried out with a Pt disk (area=0.50 cm 2 ) substrate. The Pt surface was polished to a mirror finish with 0.3 µm alumina paste and sonicated for 10 The electrochemical polymerization of aniline on a platinum electrode in aqueous HClO4 and H...

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“…In this sense, polymerization on the graphite surface may take longer to reach the state of continued growth due to the presence of surface oxygen-containing groups as previously discussed. 22 Because each PANI film deposition was carried out to the same charge, the difference in rate of deposition also confirms the difference in growth on each carbon substrate. The SEM images of the PANI film on each carbon sample show differences in the openness of the structure between the graphite support ( Figure 6B) and the coke support ( Figure 6E), with B even showing the carbon support through the matrix.…”

Section: Resultsmentioning

confidence: 86%

“…The surface groups also increase hydrophilicity of the carbon and therefore keep aniline monomers from adsorbing on the surface, resulting in a thinner polymerized PANI film. 21,22 Conversely, the coke substrate was not found to have many surface oxygen groups Figure 2. Raman spectra of G band for coke (A) and graphite (B).…”

Section: Resultsmentioning

confidence: 99%

Effect of Carbon Support on the Properties of Electrochemically Deposited Platinum and Polyaniline

Gawron

Josowicz

Janata

2017

J. Electrochem. Soc.

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Carbon has unique and desirable properties for use in applications such as fuel cells and batteries. The properties can vary widely depending on its structure and surface characteristics. Two types of carbon, a synthetic graphite produced from petroleum coke and an extruded graphite rod, were characterized using Raman spectroscopy and X-ray Photoelectron spectroscopy and the features were correlated with electrochemical properties of the material. The graphite rod was found to have a more disordered structure, greater sp 3 character, and a greater surface oxygen content as compared to the synthetic graphite from coke. Our results show that the characteristics of electrodeposited platinum and polyaniline depend on the type of substrate; the preferable carbon for producing composite materials for catalyst applications is the graphite from petroleum coke. © The Author Carbon used as a support material in fuel cells and batteries can vary in properties depending on the structure and impurities present. Reviews on carbon supports have indicated that graphite is commonly chosen to support catalytic metals due to its inert character and conductivity, and the support itself can affect performance of the fuel cell. [1][2][3][4] Composite electrodes can be produced from potentiostatic depositions of platinum and/or polyaniline (PANI) directly onto the carbon surface. Carbon supported platinum (C/Pt) is widely used for its known activity toward alcohol oxidation, 5-7 and carbon supported PANI (C/PANI), or even carbon-platinum supported PANI (C/Pt-PANI) electrodes are also attractive for the fabrication of composite catalyst materials. 8,9 Previous studies have shown that PANI can be used as a viable matrix for the insertion of catalytically active atomic-sized metal clusters, using platinum as support.10-12 We have focused our recent studies on using carbon as a support due to its benefits of being conductive, lightweight and inexpensive.13 However, in order to choose the appropriate carbon for a support electrode, understanding the effects that the substrate has on the PANI film is necessary. Dinh and Birss have compared the effects of differing types of support materials, such as noble metals and glassy carbon, on PANI properties. Impedance and CV studies on PANI grown by cycling revealed that the growth rate of the films and redox kinetics are affected by the differing supports. Specifically, slower PANI film growth was seen on glassy carbon when cycling between 0 to 1 V, while the films were more capacitive on the Pt and Au supports. However, with a larger cycling window for film deposition, the presence of surface oxygen groups was seen on the metal substrates leading to slower film growth.14 This study focuses specifically on graphitic substrates and how their structure and surface properties effect platinum deposition, as well as the growth of PANI film at constant potential. PANI growth was investigated on the surface of the carbon and on the C/Pt surface.For this study, we are using a novel synthetic graphite prod...

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Nucleation, growth and branching of polyaniline from microelectrode experiments

Cited by 162 publications

References 16 publications

Studies on electropolymerization of aniline in the presence of sodium dodecyl sulfate and its application in sensing urea

Studies on electropolymerization of aniline in the presence of sodium dodecyl sulfate and its application in sensing urea

In Situ Observation of Electrochemical Formation and Degradation Processes of Polyaniline by Fourier-Transform Infrared Spectroscopy

Effect of Carbon Support on the Properties of Electrochemically Deposited Platinum and Polyaniline

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