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

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<−0.35 V (vs. MSE), Nyquist plots show two time con...

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Detalles Bibliográficos
Autores principales: Gassa, Liliana Mabel, Lambi, J. N., Bolzán, Agustín Eduardo, Arvia, Alejandro Jorge
Formato: Articulo
Lenguaje:Inglés
Publicado: 2002
Materias:
Química
Ciencias Exactas
Thiourea
Copper
Electrochemical impedance spectroscopy
Electro-oxidation
Anodic films
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/119469
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-119469
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Química
Ciencias Exactas
Thiourea
Copper
Electrochemical impedance spectroscopy
Electro-oxidation
Anodic films
spellingShingle Química
Ciencias Exactas
Thiourea
Copper
Electrochemical impedance spectroscopy
Electro-oxidation
Anodic films
Gassa, Liliana Mabel
Lambi, J. N.
Bolzán, Agustín Eduardo
Arvia, Alejandro Jorge
Electrochemical impedance spectroscopy of thiourea electro-oxidation on copper electrodes in aqueous 0.5 M sulphuric acid
topic_facet Química
Ciencias Exactas
Thiourea
Copper
Electrochemical impedance spectroscopy
Electro-oxidation
Anodic films
description 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<−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.
format Articulo
Articulo
author Gassa, Liliana Mabel
Lambi, J. N.
Bolzán, Agustín Eduardo
Arvia, Alejandro Jorge
author_facet Gassa, Liliana Mabel
Lambi, J. N.
Bolzán, Agustín Eduardo
Arvia, Alejandro Jorge
author_sort Gassa, Liliana Mabel
title Electrochemical impedance spectroscopy of thiourea electro-oxidation on copper electrodes in aqueous 0.5 M sulphuric acid
title_short Electrochemical impedance spectroscopy of thiourea electro-oxidation on copper electrodes in aqueous 0.5 M sulphuric acid
title_full Electrochemical impedance spectroscopy of thiourea electro-oxidation on copper electrodes in aqueous 0.5 M sulphuric acid
title_fullStr Electrochemical impedance spectroscopy of thiourea electro-oxidation on copper electrodes in aqueous 0.5 M sulphuric acid
title_full_unstemmed Electrochemical impedance spectroscopy of thiourea electro-oxidation on copper electrodes in aqueous 0.5 M sulphuric acid
title_sort electrochemical impedance spectroscopy of thiourea electro-oxidation on copper electrodes in aqueous 0.5 m sulphuric acid
publishDate 2002
url http://sedici.unlp.edu.ar/handle/10915/119469
work_keys_str_mv AT gassalilianamabel electrochemicalimpedancespectroscopyofthioureaelectrooxidationoncopperelectrodesinaqueous05msulphuricacid
AT lambijn electrochemicalimpedancespectroscopyofthioureaelectrooxidationoncopperelectrodesinaqueous05msulphuricacid
AT bolzanagustineduardo electrochemicalimpedancespectroscopyofthioureaelectrooxidationoncopperelectrodesinaqueous05msulphuricacid
AT arviaalejandrojorge electrochemicalimpedancespectroscopyofthioureaelectrooxidationoncopperelectrodesinaqueous05msulphuricacid
bdutipo_str Repositorios
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