On the electrochemical behavior of formamidine disulfide on gold electrodes in acid media

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Title: On the electrochemical behavior of formamidine disulfide on gold electrodes in acid media
Authors: Cheuquepán, William | Orts Mateo, José M. | Rodes, Antonio
Research Group/s: Grupo de Espectroelectroquímica y Modelización (GEM)
Center, Department or Service: Universidad de Alicante. Departamento de Química Física | Universidad de Alicante. Instituto Universitario de Electroquímica
Keywords: Formamidine disulfide | Thiourea | Thioureate | Gold electrodes | Infrared spectroscopy | DFT
Knowledge Area: Química Física
Issue Date: 1-Mar-2016
Publisher: Elsevier
Citation: Journal of Electroanalytical Chemistry. 2016, 764: 79-87. doi:10.1016/j.jelechem.2016.01.002
Abstract: The adsorption and reactivity of formamidine disulfide (FDS) were studied at gold single crystal and thin film electrodes in perchloric acid solutions and the results of cyclic voltammetry and in situ infrared spectroscopy (SNIFTIR and ATR-SEIRAS) experiments compared with those previously obtained with thiourea (TU). In addition, optimized geometries and theoretical harmonic vibrational frequencies were obtained for adsorbed FDS, TU and thioureate from plane-wave DFT calculations using periodic surface models. These results were compared in the case of TU and thioureate to those previously obtained with a model Au cluster surface with (111) orientation. In the case of FDS, weak adsorption takes place with the S–S bond essentially parallel to the metal surface. No specific bands for adsorbed FDS can be identified in the experimental ATR-SEIRA spectra. These latter spectra suggest that adsorbed thioureate species are spontaneously formed upon dissociative adsorption of FDS when dosing this molecule at open circuit. Some of the adsorbed thioureate species undergo reductive protonation giving rise to a mixed adlayer formed by adsorbed thioureate and thiourea in a surface process which is faster when a controlled potential of 0.70 V is applied. In agreement with the observations reported when dosing TU, the ratio between TU and thioureate adsorbates is found to depend on the electrode potential, being higher for potentials close to the hydrogen evolution limit and decreasing for higher potential values.
Sponsor: The authors acknowledge the finance by Ministerio de Economía y Competitividad (project CTQ2013-44083-P) and the University of Alicante. William Cheuquepán is grateful for the award of a F.P.I. grant associated to project CTQ2009-13142.
URI: http://hdl.handle.net/10045/52738
ISSN: 1572-6657 (Print) | 1873-2569 (Online)
DOI: 10.1016/j.jelechem.2016.01.002
Language: eng
Type: info:eu-repo/semantics/article
Rights: © 2016 Elsevier B.V.
Peer Review: si
Publisher version: http://dx.doi.org/10.1016/j.jelechem.2016.01.002
Appears in Collections:INV - GEM - Artículos de Revistas

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