Comparative EIS study of the adsorption and electro-oxidation of thiourea and tetramethylthiourea on gold electrodes

Autores
Bolzán, Agustín Eduardo; Gassa, Liliana Mabel
Año de publicación
2014
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
A comparative study of the electrochemical behaviour of thiourea (TU) and tetramethylthiourea (TMTU) on gold in sulphuric acid was performed using a gold rotating disc electrode. The electrochemical impedance spectra are interpreted through an equivalent circuit involving the electrolyte resistance, a constant phase element for the capacity double layer, a charge transfer resistance and, depending on the electrode potential, a second parallel impedance element whose interpretation depends on the potential region considered. Thus, for both thioureas, the Nyquist plots for E < −0.6 V (vs. MSE) exhibit a single capacitive time constant related to the adsorption of the molecule on the electrode surface. As E increases, the Nyquist plots exhibit a new time constant assigned to the formation of a soluble complex species. This time constant appears in the potential region also related to the electro-oxidation of the thioureas to the corresponding formamidinium disulphide. This means that these processes are coupled and, therefore, only one time constant can be observed. An inductive loop at low frequencies is associated with the pitting of the gold electrode for E ≥ −0.20 V, in agreement with SEM micrographs. The value of the corresponding charge transfer resistance decreases markedly with the electrode potential, indicating the increase in the rate of the electrochemical processes. Electrodissolution of gold results more importantly in the presence of TMTU. At potential values associated with the formation of the anodic oxide layer on gold, a negative resistance is recorded, indicating the passivation of the electrode surface. Eventually, at E > 0.6 V, the electrode surface passivation disappears and the Nyquist plots exhibit two strongly overlapped capacitive constants assigned to the oxide film growth at the monolayer level and the second electro-oxidation process of thioureas, the latter resulting in the formation of carbon dioxide and sulphate ions according to FTIRRAS data.
Fil: Bolzán, Agustín Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina
Fil: Gassa, Liliana Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina
Materia
Gold
Thiourea
Tetramethylthioruea
Eis
Electro-Oxidation
Electrodissolution
Nivel de accesibilidad
acceso abierto
Condiciones de uso
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
Repositorio
CONICET Digital (CONICET)
Institución
Consejo Nacional de Investigaciones Científicas y Técnicas
OAI Identificador
oai:ri.conicet.gov.ar:11336/32276

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network_name_str CONICET Digital (CONICET)
spelling Comparative EIS study of the adsorption and electro-oxidation of thiourea and tetramethylthiourea on gold electrodesBolzán, Agustín EduardoGassa, Liliana MabelGoldThioureaTetramethylthiorueaEisElectro-OxidationElectrodissolutionhttps://purl.org/becyt/ford/1.4https://purl.org/becyt/ford/1A comparative study of the electrochemical behaviour of thiourea (TU) and tetramethylthiourea (TMTU) on gold in sulphuric acid was performed using a gold rotating disc electrode. The electrochemical impedance spectra are interpreted through an equivalent circuit involving the electrolyte resistance, a constant phase element for the capacity double layer, a charge transfer resistance and, depending on the electrode potential, a second parallel impedance element whose interpretation depends on the potential region considered. Thus, for both thioureas, the Nyquist plots for E < −0.6 V (vs. MSE) exhibit a single capacitive time constant related to the adsorption of the molecule on the electrode surface. As E increases, the Nyquist plots exhibit a new time constant assigned to the formation of a soluble complex species. This time constant appears in the potential region also related to the electro-oxidation of the thioureas to the corresponding formamidinium disulphide. This means that these processes are coupled and, therefore, only one time constant can be observed. An inductive loop at low frequencies is associated with the pitting of the gold electrode for E ≥ −0.20 V, in agreement with SEM micrographs. The value of the corresponding charge transfer resistance decreases markedly with the electrode potential, indicating the increase in the rate of the electrochemical processes. Electrodissolution of gold results more importantly in the presence of TMTU. At potential values associated with the formation of the anodic oxide layer on gold, a negative resistance is recorded, indicating the passivation of the electrode surface. Eventually, at E > 0.6 V, the electrode surface passivation disappears and the Nyquist plots exhibit two strongly overlapped capacitive constants assigned to the oxide film growth at the monolayer level and the second electro-oxidation process of thioureas, the latter resulting in the formation of carbon dioxide and sulphate ions according to FTIRRAS data.Fil: Bolzán, Agustín Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Gassa, Liliana Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaSpringer2014-02info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionhttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfapplication/pdfhttp://hdl.handle.net/11336/32276Gassa, Liliana Mabel; Bolzán, Agustín Eduardo; Comparative EIS study of the adsorption and electro-oxidation of thiourea and tetramethylthiourea on gold electrodes; Springer; Journal of Applied Electrochemistry; 42; 2; 2-2014; 279-2920021-891XCONICET DigitalCONICETenginfo:eu-repo/semantics/altIdentifier/doi/10.1007/s10800-013-0621-7info:eu-repo/semantics/altIdentifier/url/https://link.springer.com/article/10.1007%2Fs10800-013-0621-7info:eu-repo/semantics/openAccesshttps://creativecommons.org/licenses/by-nc-sa/2.5/ar/reponame:CONICET Digital (CONICET)instname:Consejo Nacional de Investigaciones Científicas y Técnicas2025-09-29T10:00:41Zoai:ri.conicet.gov.ar:11336/32276instacron:CONICETInstitucionalhttp://ri.conicet.gov.ar/Organismo científico-tecnológicoNo correspondehttp://ri.conicet.gov.ar/oai/requestdasensio@conicet.gov.ar; lcarlino@conicet.gov.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:34982025-09-29 10:00:41.528CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicasfalse
dc.title.none.fl_str_mv Comparative EIS study of the adsorption and electro-oxidation of thiourea and tetramethylthiourea on gold electrodes
title Comparative EIS study of the adsorption and electro-oxidation of thiourea and tetramethylthiourea on gold electrodes
spellingShingle Comparative EIS study of the adsorption and electro-oxidation of thiourea and tetramethylthiourea on gold electrodes
Bolzán, Agustín Eduardo
Gold
Thiourea
Tetramethylthioruea
Eis
Electro-Oxidation
Electrodissolution
title_short Comparative EIS study of the adsorption and electro-oxidation of thiourea and tetramethylthiourea on gold electrodes
title_full Comparative EIS study of the adsorption and electro-oxidation of thiourea and tetramethylthiourea on gold electrodes
title_fullStr Comparative EIS study of the adsorption and electro-oxidation of thiourea and tetramethylthiourea on gold electrodes
title_full_unstemmed Comparative EIS study of the adsorption and electro-oxidation of thiourea and tetramethylthiourea on gold electrodes
title_sort Comparative EIS study of the adsorption and electro-oxidation of thiourea and tetramethylthiourea on gold electrodes
dc.creator.none.fl_str_mv Bolzán, Agustín Eduardo
Gassa, Liliana Mabel
author Bolzán, Agustín Eduardo
author_facet Bolzán, Agustín Eduardo
Gassa, Liliana Mabel
author_role author
author2 Gassa, Liliana Mabel
author2_role author
dc.subject.none.fl_str_mv Gold
Thiourea
Tetramethylthioruea
Eis
Electro-Oxidation
Electrodissolution
topic Gold
Thiourea
Tetramethylthioruea
Eis
Electro-Oxidation
Electrodissolution
purl_subject.fl_str_mv https://purl.org/becyt/ford/1.4
https://purl.org/becyt/ford/1
dc.description.none.fl_txt_mv A comparative study of the electrochemical behaviour of thiourea (TU) and tetramethylthiourea (TMTU) on gold in sulphuric acid was performed using a gold rotating disc electrode. The electrochemical impedance spectra are interpreted through an equivalent circuit involving the electrolyte resistance, a constant phase element for the capacity double layer, a charge transfer resistance and, depending on the electrode potential, a second parallel impedance element whose interpretation depends on the potential region considered. Thus, for both thioureas, the Nyquist plots for E < −0.6 V (vs. MSE) exhibit a single capacitive time constant related to the adsorption of the molecule on the electrode surface. As E increases, the Nyquist plots exhibit a new time constant assigned to the formation of a soluble complex species. This time constant appears in the potential region also related to the electro-oxidation of the thioureas to the corresponding formamidinium disulphide. This means that these processes are coupled and, therefore, only one time constant can be observed. An inductive loop at low frequencies is associated with the pitting of the gold electrode for E ≥ −0.20 V, in agreement with SEM micrographs. The value of the corresponding charge transfer resistance decreases markedly with the electrode potential, indicating the increase in the rate of the electrochemical processes. Electrodissolution of gold results more importantly in the presence of TMTU. At potential values associated with the formation of the anodic oxide layer on gold, a negative resistance is recorded, indicating the passivation of the electrode surface. Eventually, at E > 0.6 V, the electrode surface passivation disappears and the Nyquist plots exhibit two strongly overlapped capacitive constants assigned to the oxide film growth at the monolayer level and the second electro-oxidation process of thioureas, the latter resulting in the formation of carbon dioxide and sulphate ions according to FTIRRAS data.
Fil: Bolzán, Agustín Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina
Fil: Gassa, Liliana Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina
description A comparative study of the electrochemical behaviour of thiourea (TU) and tetramethylthiourea (TMTU) on gold in sulphuric acid was performed using a gold rotating disc electrode. The electrochemical impedance spectra are interpreted through an equivalent circuit involving the electrolyte resistance, a constant phase element for the capacity double layer, a charge transfer resistance and, depending on the electrode potential, a second parallel impedance element whose interpretation depends on the potential region considered. Thus, for both thioureas, the Nyquist plots for E < −0.6 V (vs. MSE) exhibit a single capacitive time constant related to the adsorption of the molecule on the electrode surface. As E increases, the Nyquist plots exhibit a new time constant assigned to the formation of a soluble complex species. This time constant appears in the potential region also related to the electro-oxidation of the thioureas to the corresponding formamidinium disulphide. This means that these processes are coupled and, therefore, only one time constant can be observed. An inductive loop at low frequencies is associated with the pitting of the gold electrode for E ≥ −0.20 V, in agreement with SEM micrographs. The value of the corresponding charge transfer resistance decreases markedly with the electrode potential, indicating the increase in the rate of the electrochemical processes. Electrodissolution of gold results more importantly in the presence of TMTU. At potential values associated with the formation of the anodic oxide layer on gold, a negative resistance is recorded, indicating the passivation of the electrode surface. Eventually, at E > 0.6 V, the electrode surface passivation disappears and the Nyquist plots exhibit two strongly overlapped capacitive constants assigned to the oxide film growth at the monolayer level and the second electro-oxidation process of thioureas, the latter resulting in the formation of carbon dioxide and sulphate ions according to FTIRRAS data.
publishDate 2014
dc.date.none.fl_str_mv 2014-02
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
http://purl.org/coar/resource_type/c_6501
info:ar-repo/semantics/articulo
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/11336/32276
Gassa, Liliana Mabel; Bolzán, Agustín Eduardo; Comparative EIS study of the adsorption and electro-oxidation of thiourea and tetramethylthiourea on gold electrodes; Springer; Journal of Applied Electrochemistry; 42; 2; 2-2014; 279-292
0021-891X
CONICET Digital
CONICET
url http://hdl.handle.net/11336/32276
identifier_str_mv Gassa, Liliana Mabel; Bolzán, Agustín Eduardo; Comparative EIS study of the adsorption and electro-oxidation of thiourea and tetramethylthiourea on gold electrodes; Springer; Journal of Applied Electrochemistry; 42; 2; 2-2014; 279-292
0021-891X
CONICET Digital
CONICET
dc.language.none.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv info:eu-repo/semantics/altIdentifier/doi/10.1007/s10800-013-0621-7
info:eu-repo/semantics/altIdentifier/url/https://link.springer.com/article/10.1007%2Fs10800-013-0621-7
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
eu_rights_str_mv openAccess
rights_invalid_str_mv https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
dc.format.none.fl_str_mv application/pdf
application/pdf
dc.publisher.none.fl_str_mv Springer
publisher.none.fl_str_mv Springer
dc.source.none.fl_str_mv reponame:CONICET Digital (CONICET)
instname:Consejo Nacional de Investigaciones Científicas y Técnicas
reponame_str CONICET Digital (CONICET)
collection CONICET Digital (CONICET)
instname_str Consejo Nacional de Investigaciones Científicas y Técnicas
repository.name.fl_str_mv CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicas
repository.mail.fl_str_mv dasensio@conicet.gov.ar; lcarlino@conicet.gov.ar
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