An Admittance Study of the Copper Electrode

Glarum, S. H.; Marshall, J. H.

doi:10.1149/1.2127584

Cited by 17 publications

(13 citation statements)

References 24 publications

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“…In this case, the simultaneous electro-oxidation of FDS and Cu(I) Ã/ TU complexes, along with the electrodissolution of copper to aqueous Cu(II) ions takes place. Correspondingly, the nature and electrical characteristics of the anodic film change from a predominantly insoluble Cu(I) Ã/TU complex film to a heterogeneous layered film consisting of copper sulphide and copper sludge [35]. The partial rupture of the copper sulphide-containing film leads to pitting corrosion.…”

Section: Eis In Ranges I Ii and Iiimentioning

confidence: 99%

Electrochemical impedance spectroscopy of thiourea electro-oxidation on copper electrodes in aqueous 0.5 M sulphuric acid

Gassa

Lambi

Bolzán

et al. 2002

Journal of Electroanalytical Chemistry

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The anodisation of copper electrodes in aqueous thiourea (TU) containing 0.5 M sulphuric acid is studied by electrochemical impedance spectroscopy (EIS) combined with rotating disk electrode and ring-disk electrode, SEM and EDAX techniques. For E B/ (/0.35 V (vs. MSE), Nyquist plots show two time constants. The first one, which appears at high frequencies, involves the contribution of the double layer capacity and the charge transfer resistance related to the electro-oxidation of TU to formamidine disulphide (FDS). The second time constant, which is observed at low frequencies, is related to complex electrochemical and chemical processes following TU electro-oxidation to FDS. Depending on the applied potential, this time constant can be assigned to either an electroadsorption process from TU electro-oxidation products or an electrochemical process under diffusion through an anodic film. At high TU concentration, the low frequency time constant corresponds to the typical response of a pure capacitor due to the formation of a thick anodic film under a diffusion controlled process. In this case, for E ]/(/0.35 V, Nyquist plots exhibit at least three time constants and an inductive loop. The inductive loop is due to surface relaxation associated with copper pitting. The formation of different types of anodic films is confirmed by SEM observations. EIS results are consistent with the complex reaction pathway previously proposed for the anodisation of copper in aqueous TU-containing acid solutions.

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Section: Eis In Ranges I Ii and Iiimentioning

confidence: 99%

Electrochemical impedance spectroscopy of thiourea electro-oxidation on copper electrodes in aqueous 0.5 M sulphuric acid

Gassa

Lambi

Bolzán

et al. 2002

Journal of Electroanalytical Chemistry

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“…The somewhat greater diffusion coefficient in fluoboric acid solutions may reflect formation of complexes such as SnF3-. The hydrolysis reaction (21) BFd-+ H20 ~.~ HF + BFsOH- [12] leads to free F-which forms a series of strong Sn + + complexes (22). A-C measurements verify kinetic control by a diffusion process .at low frequencies and independently yield diffusion coefficients agreeing with those derived from RDE limiting currents.…”

Section: Discussionmentioning

confidence: 99%

“…A tin wire mounted in rigid glass capillary tubing served as the reference electrode. The cell was thermostated at 25 ~ The experimental apparatus and procedures have been previously described (12). Two types of admittance measurements, Y%(~) and Y*~o(~), were used in this work.…”

Section: Methodsmentioning

confidence: 99%

An Admittance Study of the Tin Electrode

Glarum¹,

Marshall²

1983

J. Electrochem. Soc.

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Voltammetric and admittance measurements for tin deposition at a rotating disk electrode from sulfuric and fluoboric acid Sn ++ solutions have been analyzed. Apparent exchange current densities ca. 10 AJem ~ are reduced 100-fold upon addition of polyethylene glycol. With or without the additive, the conductance representing the exchange process varies with potential directly as the surface Sn ++ concentration. Localized three-dimensional concentration polarization zones in the electrolyte phase arising from discrete growth sites form the preferred interpretation, although an alternative kinetic process occurring prior to charge transfer cannot be excluded as the rate-limiting step.

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“…The electronically conducting film of polyaniline may still undergo a second insulating transition following upon a positive shift of potential above ca. 0.7-0.8 V. [3][4] In contrast with the former, reductive transformation, the latter one leads progressively to irreversible changes in physicochemical properties of polyaniline. One of the currently employed means of modifying conducting polymer films consists in incorporating metal microparticles.…”

mentioning

confidence: 99%

Enhanced rate of redox conversion of polyaniline films induced by the incorporation of platinum microparticles

Kostecki¹,

Ulmann²,

Augustyński³

et al. 1993

J. Phys. Chem.

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Relatively thick (in the range of 50 pm) electrochemically grown polyaniline films, with and without incorporated platinum microparticles, have been characterized by means of ac impedance measurements. In particular, resistance changes for both kinds of films were followed in situ (in 1 M aqueous H2S04 solution) as a function of potential. Rather unexpectedly, the rate of redox conversion of such polyaniline films is found to increase significantly in the presence of less than 100 pg cm-2 of electrodeposited metal particles dispersed inside the polymer layer.This letter describes some new observations concerning changes in the conductivity behavior of polyaniline films, induced by their modification with dispersed metal (Pt) microparticles. Electroactive polyaniline films, with the nominal structure similar to emeraldine,' can be electrochemically formed on metal or semiconductor surfaces using, for example, a potential cycling procedure.2 The oxidized, electronically conducting form of polyaniline is reversibly transformed into the reduced, isolating form by changing its electrochemical potential to negative values (below ca. -0.1 V vs SCE in 1 M H2S04). The electronically conducting film of polyaniline may still undergo a second insulating transition following upon a positive shift of potential above ca. 0.7-0.8 V.3,4 In contrast with the former, reductive transformation, the latter one leads progressively to irreversible changes in physicochemical properties of polyaniline.One of the currently employed means of modifying conducting polymer films consists in incorporating metal microparticles. It is known that the polyaniline films including, for example, dispersed Pt particles exhibit enhanced electrocatalytic activity toward such reactions as oxidation of methanol536 or formic In contrast, much less attention (if any) has been paid to other than electrocatalytic properties of such composite materials. The present report focuses on the significant increase of the conversion rate between conducting (oxidized) and poorly conducting (reduced) state of the polyaniline films brought about by the deposition inside the film of Pt microparticles. These findings are particularly important in view of the potential application of polyaniline in electrochromic displays3 and in electrochemical sensors9 and may throw some additional light on the mechanism of charge transfer in this polymer. The changes in conductivity of the films were followed in situ by means of impedance measurements. Experimental SectionThe polyaniline films were formed on planar gold electrodes of ca. 0.18 cm2 exposed geometric area. The films were grown electrochemically by cycling continuously, at 50 mV s-l, the electrode potential between41 8 and 0.745 Vvs SCE. To initiate the deposition the anodic limit of the first scan was extended to 0.855 V. The electropolymerization was carried out in 2.2 M solution of sulfuric acid (Romil, analytical grade) containing 0.5 M dm-3 of freshly distilled aniline (Fluka).Platinum microparticles were incorporated in...

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An Admittance Study of the Copper Electrode

Abstract: 1014 cm -3 and carrier mobilities of approximately 50 cm 2 V -1 sec -1 can be achieved in this manner.

Cited by 17 publications

References 24 publications

Electrochemical impedance spectroscopy of thiourea electro-oxidation on copper electrodes in aqueous 0.5 M sulphuric acid

Electrochemical impedance spectroscopy of thiourea electro-oxidation on copper electrodes in aqueous 0.5 M sulphuric acid

An Admittance Study of the Tin Electrode

Enhanced rate of redox conversion of polyaniline films induced by the incorporation of platinum microparticles

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