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1.
J. Tamm A. Alumaa A. Hallik U. Johanson L. Tamm T. Tamm 《Russian Journal of Electrochemistry》2002,38(2):182-187
The influence of anions ClO4
–, NO3
–, Cl–, SO4
2–, and DDS– (dodecyl sulfate) on the cyclic voltammetric response of polypyrrole-modified electrodes is studied. The change in the film composition is examined by electron probe microanalysis. It is established that essential changes in the shape of voltammograms take place during cycling if the anions are not sufficiently freely mobile in the polymer film and insertion of cations from the solution is necessary to guarantee electroneutrality of the system. Some differences between the mobility of Cl– ions and ClO4
– or NO3
– ions are in good agreement with the results of semi-empirical quantum chemical calculations showing that the interaction of Cl– and Br– ions with pyrrole oligomers is stronger than that of NO3
– or ClO4
– ions. Nevertheless, it is established that the peak current determined from voltammograms increases linearly with the increase of the scan rate with very high correlation coefficient. It means that it is possible to describe the behavior of ClO4
–, NO3
– and Cl– ions in the framework of the model of free ions. The redox behavior of the PPy films doped with anions of low mobility such as SO4
2– and DDS– depends essentially on the nature of cations in the test solution. It is found that the mobility of cations increases in the row Li+ < Na+ < K+ < Cs+. The mobility of DDS– ions in the PPy in ethanolic solution is significantly higher and their electrochemical properties are quite similar to PPy|Cl or NO3
– film in aqueous solution. 相似文献
2.
简要介绍本研究组自上世纪80年代以来在导电聚合物的电化学制备和电化学性质研究中取得的一些主要成果,包括吡咯电化学聚合条件的影响、电化学聚合反应机理及其反应动力学、导电聚吡咯的两种掺杂结构及其两步电化学氧化还原过程和电化学过氧化的机理、导电聚苯胺的电化学性质、导电聚合物稳定性的电化学解释等等. 相似文献
3.
Pilar Pérez Mañogil Antonio J. Fernández Romero 《Journal of Solid State Electrochemistry》2010,14(5):841-849
Polypyrrole/poly(vinyl sulfonate) (PPy/PVS) films have been synthesized by a potentiodynamic method in aqueous solution. The
voltammetric study of this polymer in acetonitrile (MeCN) reveals an anomalous behavior of its redox process in the three
electrolytes used: LiClO4, LiF3CSO3, and (Bu)4NClO4. The anion and cation sizes of the electrolyte clearly affect the reduction/oxidation process of a PPy/PVS film in MeCN medium.
This result is explained by both anions and cations participating during the redox reaction of this polymer in MeCN medium:
initially, the cations penetrate the polymer forming ion pairs with sulfonate groups, and the anions behave as the main mobile
species during the potential sweeps. However, a large cation or anion will penetrate with difficulty inside the polymer, providing
a lower amount of electroactive polymeric chains and a lower value of peak charges. 相似文献
4.
Charles Y. Cummings Alistair H. Roweth Andrew K.Z. Ching A. Toby A. Jenkins John M. Mitchels Sara Shariki Soon Yee Liew Wim Thielemans Darren A. Walsh Frank Marken 《Electrochemistry communications》2010,12(12):1722-1726
Molecular layer-by-layer assembly from pre-saturated aqueous solutions of Fe3+ and phytate is employed to build up iron phytate deposits on tin-doped indium oxide (ITO) electrodes. Globular films with approximately 1 nm growth per layer are observed by AFM imaging and sectioning. In electrochemical experiments the iron phytate films show well-defined voltammetric responses consistent with an immobilised Fe(III/II) redox system in aqueous (LiClO4, NaClO4, KClO4, phosphate buffer) and in ethanolic (LiClO4, NaClO4, NBu4ClO4) electrolyte solutions. The Fe(III/II) redox system is reversible and cation insertion/expulsion occurs fast on the timescale of voltammetric experiments even for more bulky NBu4+ cations and in ethanolic solution. Peak shape analysis and scan rate dependent midpoint potentials suggest structural changes accompanying the redox process and limiting propagation. Iron phytate is proposed as a versatile and essentially colourless cation electro-insertion material and as a potential energy storage material. 相似文献
5.
Microstructures with hollow interiors, such as microspheres, microcrocks, microbowls, and micropumpkins, were prepared through the direct electrochemical oxidation of pyrrole in an aqueous solution of poly(styrene sulfonic acid) (PSSA). Scanning electron microscopy demonstrated that the microstructures possessed hollow interiors. The addition of polymeric doping ions made the skins of the microstructures very smooth, and several novel structures were observed. The morphology of the microstructures was simply modulated through changes in the electrochemical conditions. Raman and Fourier transform infrared characterizations indicated that the microstructures were made of conductive polypyrrole (PPy) doped by polymeric anions of poly(styrene sulfonate), and X‐ray diffraction showed that the microstructures were amorphous. Thermogravimetric analysis indicated that PPy–PSSA composite films with microstructures had higher thermal stability than pure PPy, PPy‐coated PSSA microspheres, and naphthalene sulfonic acid doped PPy microstructures. Furthermore, PPy–PSSA composite films with microstructures showed cation‐exchange behavior during the redox process in aqueous solutions of sodium dodecyl benzenesulfonate. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3170–3177, 2004 相似文献
6.
Conducting polypyrrole (PPy) and poly(pyrrole-2,6-dimethyl-β-cyclodextrin) [poly(Py-β-DMCD)] films were prepared by electrode
potential cycling on a gold electrode in aqueous and nonaqueous (acetonitrile) electrolyte solutions containing lithium perchlorate.
The resulting products were characterized with cyclic voltammetry, in situ UV–Vis spectroscopy, and in situ conductivity measurements.
For the electrosynthesis of poly(Py-β-DMCD), a (1:1) (mole–mole) (Py-β-DMCD) supramolecular cyclodextrin complex of pyrrole
previously characterized with proton NMR spectroscopy was used as starting material. A different cyclic voltammetric behavior
was observed for pyrrole and the poly(Py-β-DMCD) complex in aqueous and nonaqueous solutions during electrosynthesis. The
results show that in both solutions in the presence of cyclodextrin, the oxidation potential of pyrrole monomers increases.
However, the difference of oxidation potentials for films prepared in aqueous solution is larger than for the films prepared
in nonaqueous solution. In situ conductivity measurements of the films show that films prepared in acetonitrile solution are
more conductive than those synthesized in aqueous solutions. Maximum conductivity can be observed for PPy and poly(Py-β-DMCD)
films prepared in nonaqueous solution in the range of 0.10 < E
Ag/AgCl < 0.90 V and 0.30 < E
Ag/AgCl < 0.90 V, respectively. In situ UV–Vis spectroelectrochemical data for both films prepared potentiodynamically by cycling
the potentials from −0.40 < E
Ag/AgCl < 0.90 V in nonaqueous solutions are reported.
This paper is dedicated to Prof. Alan Bond on the occasion of his 65th birthday in recognition of his numerous contributions
toward electrochemistry. 相似文献
7.
The influence of different divalent cations (M2+) on the electrochemical charging/discharging process of polypyrrole/sulfate (PPy/SO4) films has been investigated. In principle, two different types of M2+ were found: (a) cations that cause the break-in phenomenon in the PPy film during electrochemical cycling with a gradual
increase of film electroactivity and (b) cations in whose solutions the PPy film remains mainly electroinactive. Certain correlations
have been drawn between several physico-chemical properties of the investigated cations and the break-in and passivation phenomena.
The break-in and passivation phenomena were found to be influenced by the size and deformability of the cation hydration shell,
ion covalent index and softness, as well as by the pH value of the test solution. 相似文献
8.
《Electrochemistry communications》2002,4(10):753-758
Preparation and electrochemical behaviour of bilayer films consisting of iron(III) hexacyanoferrate, well known as Prussian Blue, and of poly[4,4′-bis(butylsulphanyl)-2,2′-bithiophene], on a platinum electrode, are reported. The electrochemical features of the Prussian Blue/conducting polymer bilayer system are examined in aqueous and acetonitrile solutions. Cyclic voltammetric studies show that, in acetonitrile solvent, the inner layer Prussian Blue is electroactive to some extent, though the electrochemical response of the system is mainly accounted for by poly[4,4′-bis(butylsulphanyl)-2,2′-bithiophene] outer layer. On the other hand, in aqueous solution Prussian Blue exhibits good electroactivity. Under specific experimental conditions, the individual redox behaviour of each constituent of the bilayer is evidenced in the two solvents separately, i.e., that of PB and that of poly[4,4′-bis(butylsulphanyl)-2,2′-bithiophene] in aqueous and in organic solvent, respectively. However, interesting reciprocal influences are evident in the current/potential curves recorded under conditions which are discussed. 相似文献
9.
Fernandez Romero AJ López Cascales JJ Fernandez Otero T 《The journal of physical chemistry. B》2005,109(2):907-914
Polypyrrole/poly(vinyl sulfonate) (PPy/PVS) films in acetonitrile containing 0.1 M LiClO4 were studied by cyclic voltammetry. Consecutive voltammograms pointed to a continuous increase in the charge involved in the process, suggesting a rise in the number of the electroactive participants involved in the redox process. However, voltammograms obtained for the PPy/ClO4 films in analogous conditions pointed to a steady-state behavior from the very early cycles. Theoretical studies based on the Nernst and Butler-Volmer equations indicated that perchlorate ions are involved during the oxidation/reduction process of the PPy/PVS films when the steady state is reached. This result was confirmed by "ex situ" energy-dispersive X-ray analysis of the films. In this regard, the electrochemical behavior of PPy/PVS polymers was similar to that of PPy/ClO4 films when a high number of cycles were carried out. The exchange of ClO4- during the redox reaction of the PPy/PVS films made it necessary to incorporate Li+ cations inside the polymer during the initial voltammetric cycles to compensate for the negative charges of PVS polyanions. Li+ cations are mainly stabilized inside the polymer by the ion pairs formed with the sulfonated groups of the PVS. An increase and shift of the voltammetric cycles indicated a restructuring of the polymeric chains with consecutive scans. 相似文献
10.
Krzysztof Maksymiuk Ann-Sofi Nybck Johan Bobacka Ari Ivaska Andrzej Lewenstam 《Journal of Electroanalytical Chemistry》1997,430(1-2)
The potentiometric response of electrodes coated with polypyrrole or poly(N-methylpyrrole) films with different doping anions was studied in solutions containing the redox couples: Fe(CN)63−/4−, Ru(NH3)63+/2+ and Fe(Ill)/Fe(II). The stable potential measured with the electrodes was the potential of the redox couple. The response time was instant for polypyrrole doped with dodecylsulphate ions, PPy(DS) and slow for the polymers doped with mobile anions. On the basis of electrochemical measurements and chemical analysis by EDAX spectroscopy it was found that with the PPy(DS) electrode the potentiometric response was of the ‘metallic’ type, with no change in the oxidation state of the bulk polymer. With the other polymer systems studied reduction or oxidation of the polymer bulk took place when it was in contact with a redox couple in the solution. 相似文献
11.
Electrochemical derivatization of carbon surface by reduction of in situ generated diazonium cations
The derivatization of a glassy carbon electrode surface was achieved by electrochemical reduction of several in situ generated diazonium cations. The diazonium cations were synthesized in the electrochemical cell by reaction of the corresponding amines with NaNO2 in aqueous HCl. The versatility of the method was demonstrated by using six diazonium cations. This deposition method, which involves simple reagents and does not require the isolation and purification of the diazonium salt, enabled the grafting of covalently bounded layers which exhibited properties very similar to those of layers obtained by the classical derivatization method involving isolated diazonium salt dissolved in acetonitrile or aqueous acid solution. Cyclic voltammetry and electrochemical impedance spectroscopy carried out in aqueous solutions containing electroactive redox probe molecules such as Fe(CN)6(3-/4-) and Ru(NH3)6(3+) confirmed the barrier properties of the deposited layers. The chemical composition of the grafted layers was determined by X-ray photoelectron spectroscopy and surface coverage in the range 3 x 10(-10) to 6 x 10(-10) mol cm(-2) was estimated for films grown in our experimental conditions. 相似文献
12.
Nataliia V. Talagaeva Ekaterina V. Zolotukhina Polina A. Pisareva Mikhail A. Vorotyntsev 《Journal of Solid State Electrochemistry》2016,20(5):1235-1240
Composite materials of Prussian blue–polypyrrole (PB/PPy) on the surface of indium tin oxide (ITO)-coated glasses were obtained via one-step chemical (redox) and one-stage electrochemical procedures in mixed solution of iron (III), hexacyanoferrate (III), and pyrrole with various concentration ratios of components in nitrate supporting electrolyte. Electrochemical stability of composite films depends on the amount of Py in synthetic solution, whereas color contrast coefficient values depend on the type of synthetic procedure. PB/PPy film electrochromic response (tested by spectroelectrochemical potentiodynamic measurements) was compared with response of both pure PB and pure PPy films. It was shown that degradation of composite films occurs due to PB component instability in Prussian white form. The highest value of color contrast coefficient and great electrochemical stability were revealed for composite films obtained via redox-synthesis procedure from solution with 0.1 mM [Fe3+ + Fe(CN)6 3?] and 1.0 mM Ру (PB/PPy-Ch-1:1:10 system). 相似文献
13.
Tamm J. Johanson U. Marandi M. Tamm T. Tamm L. 《Russian Journal of Electrochemistry》2004,40(3):344-348
Experimental and theoretical methods have been used for characterization of the properties of polypyrrole films. The AFM studies show that the morphology of polypyrrole (PPy) films on polycrystalline gold electrodes at the first stages of synthesis depends on the structure of the metal surface. It was established that mobility of anions depends remarkably on the rate of electrodeposition of the polymer film. If PPy film was deposited at relatively low current density, mobility of ClO-
4 anion was not high enough to guarantee electroneutrality during redox cycling and cations take part in this process especially when Li+ cations were replaced by more mobile + cations. Semiempirical (AM1 and PM3) quantum-chemical methods were used for theoretical studies. It was established that different size and charge of the anions together with the variation in doping levels give rise to a different optimal conformation of oligopyrrole cations which, in turn, define the resulting polymer to be either all-anti (common linear chains) or all-syn (formation of helical structures) or a combination of the two. 相似文献
14.
氟尿嘧啶的电化学控制释放 总被引:2,自引:0,他引:2
本文探讨了抗癌药物氟尿嘧啶在聚吡咯膜修饰玻碳电极上的电化学控制释放,结果表明药物自膜中的释放是聚吡咯膜的电化学氧化还原过程决定的。其释放量可由还原电位进行控制,并与还原电量和膜厚呈现良好的线性关系。 相似文献
15.
Péter S Tóth Christian Perruchot Amani Chams Nabiha Maslah Mohamed Jouini Csaba Visy 《Journal of Solid State Electrochemistry》2013,17(3):635-641
In opposite with the usually applied synthesis in organic media, the polymerization of bithiophene in aqueous media has been studied. The use of a non-ionic surfactant (polyoxyethylene octyl phenyl ether (Triton X-100)) is useful not only to solubilize the hydrophobic monomer but it is also important to incorporate various—biologically and catalytically active—additives. In this paper, the optimization of the polymerization conditions as well as the characterization of the electrochemical, spectral and mass exchange behavior of these composite films is summarized. The layers have shown imperceptible electroactivity in monomer-free aqueous LiClO4 solutions, and electrochemical quartz crystal microbalance (EQCM) studies exhibited scarce ion movements, caused assumingly by the fact that the dopant species—moving together with their hydrate shell in the aqueous media—could not penetrate into the hydrophobic film. In contrast, nice reversible redox transformation could be obtained in organic medium such as acetonitrile, where—according to the EQCM results—the charge carrier formation/depletion is accompanied by the incorporation/removal of ClO4 ? anions. In this solution, the spectral changes have proved the transformation into the conducting state, connected to both mono- and di-cation forms. The incorporation of the surfactant has been demonstrated by the extraordinary surface morphology of the polybithiophene (pBT) films, characterized by scanning electron microscopy. The elementary composition of the curious shell-shaped objects, monitored by energy dispersive X-ray spectroscopy (EDX), evidenced the presence of Triton X-100 by the increased C/S ratio compared to neat polybithiophene, while the Cl/S data reflected the changes connected to the doping level as a consequence of ClO4 ? anion movements. Moreover, ex situ attenuated total reflectance (ATR) FT–IR measurements clearly showed the existence of C―O bonds, also proving the successful functionalization by the surfactant, built permanently into the redox active films. 相似文献
16.
A. Pailleret N. T. L. Hien D. T. M. Thanh C. Deslouis 《Journal of Solid State Electrochemistry》2007,11(8):1013-1021
Composite materials based on iron-oxide nanoparticles (magnetite, hematite, and maghemite) and tetraoxalate-doped polypyrrole
(PPy) were electrochemically generated from aqueous solutions. Their composition was determined using electrochemical quartz
crystal microbalance experiments. The oxide percentage in mass was found to vary from 17 to 27% depending on the oxide identity.
They were all shown to be fascinating candidates as protective materials against corrosion of iron and carbon steel materials
although maghemite-nanoparticle-loaded polypyrrole films offer the best performances. An anionic surfactant (sodium dodecylsulfate)
was added to the electrodeposition solution to avoid the formation of clusters. These anions were also shown to improve the
conductivity of the resulting PPy films, while the presence of oxide nanoparticles tends to decrease this same surface conductivity.
On the other hand, the correlation between the morphology and the local conductivity appears to be more obvious in the absence
of anionic surfactants than in their presence. This aspect is discussed although it still needs further investigation.
Contribution to the International Workshop on Electrochemistry of Electroactive Materials (WEEM-2006), Repino, Russia, 24–29
June 2006. 相似文献
17.
S. Mokrane L. Makhloufi H. Hammache B. Saidani 《Journal of Solid State Electrochemistry》2001,5(5):339-347
Conductive polypyrrole (PPy) films and PPy films containing Ge microparticles were synthesized by anodic oxidation of pyrrole
in acidic nitrate solutions using a bare passivated titanium electrode. Well-adhering black PPy films were obtained both under
galvanostatic and potentiodynamic polarization. After the formation of the PPy film, during the first anodic cycle, an increase
of the anodic deposition current with the number of cycles was observed, revealing the increase of conductivity of the growing
film. The variations of the electrode surface area were estimated by impedance spectroscopy measurements. The kinetics of
the PPy film formation is controlled by diffusion of the Py monomer in the solution. The diffusion coefficient, estimated
by two different methods, was ca. 2×10–6 cm2 s–1. The reduction rate of oxygen and protons at the Ti/PPy/Ge electrodes depends on how the Ge microparticles are incorporated
in the PPy film. Optimum conditions for this incorporation are realized with thin PPy films and high Ge loading. Thermogravimetric
analysis shows that the PPy film containing Ge microparticles is more thermally stable than the blank PPy film.
Electronic Publication 相似文献
18.
Electrical and morphological properties of polypyrrole (PPy) films were studied during and after their electrochemical growth under various experimental conditions on a nanometer scale using a current-sensing atomic force microscope (CS-AFM). Of acetonitrile (ACN) solutions containing various amounts of water, one that contained 1.0% water produced the best quality films in their electrical and morphological properties in terms of homogeneities. The degree of doping, as well as time evolution of the film structure and its conductivity, of the PPy films was investigated during their growth in water and ACN with 1.0% water by obtaining the current images at a few designated growing stages, and the results were compared. Well-doped, conductive films were obtained from the very early stage during the electrodeposition of PPy in the ACN solution, while the films were poorly doped in water. As the film deposition progressed further in both aqueous and nonaqueous media, the doped areas spread over the whole surface leading to a more homogeneously conducting film. The current-voltage traces were obtained at each growing stage, which showed that the conductivity increases in both media as the PPy grows; the conductivity of the film grown in ACN is much higher than that of the film grown in water at all growing stages. The electrical properties of the PPy film deteriorated gradually upon exposure to air. 相似文献
19.
In this work, polypyrrole films with ferrocenecarboxylic acid incorporated (PPy/FCA) were prepared on a glassy carbon (GC)
electrode in chloroform as an aprotic solvent with low dielectric constant, convenient for the preparation of the films by
a precipitation mechanism. The electrochemical behaviour of the PPy/FCA-coated GC electrode was studied by cyclic voltammetry
in aqueous solution with low pH. The results obtained show that the electrochemical response of FCA incorporated in polypyrrole
is consistent with a reversible surface oxidation. An obvious electrocatalytic effect of PPy/FCA on the oxidation of ascorbic
acid is observed in aqueous solution.
Received: 30 July 1998 / Accepted: 3 March 1999 相似文献
20.
Nitrate-doped polypyrrole (PPy) films on a glassy carbon substrate have been prepared electrochemically in aqueous, acetonitrile, and propylene carbonate solutions for use as nitrate sensors. Lithium nitrate, sodium nitrate, nitric acid, tetraethylammonium p-toluene sulfonate (TS), and tetradodecylammonium nitrate (TDN) were employed as electrolytes. The effect of dibutylphthalate (DBP) as a plasticizer on the sensitivity and lifetime of PPy film sensors was also investigated. A Nernstian behavior with a slope of 56.9 m V/decade over 0.1–7.4 × 10−5 M NO and a detection limit of 4.7 × 10−5 M were observed for the polymer sensor prepared in acetonitrile solution containing lithium nitrate and 15% plasticizer (DBP). A lifetime of more than 6 months for this PPy film electrode was obtained. 相似文献