Hydroxyurea electrooxidation at gold electrodes. In situ infrared spectroelectrochemical and DFT characterization of adsorbed intermediates

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Título: Hydroxyurea electrooxidation at gold electrodes. In situ infrared spectroelectrochemical and DFT characterization of adsorbed intermediates
Autor/es: Cheuquepán, William | Orts Mateo, José M. | Rodes García, Antonio
Grupo/s de investigación o GITE: Grupo de Espectroelectroquímica y Modelización (GEM)
Centro, Departamento o Servicio: Universidad de Alicante. Departamento de Química Física | Universidad de Alicante. Instituto Universitario de Electroquímica
Palabras clave: Au(111) | Au(100) | Gold thin film | Hydroxyurea electrooxidation | IRRAS | ATR-SEIRAS
Área/s de conocimiento: Química Física
Fecha de publicación: 20-ago-2017
Editor: Elsevier
Cita bibliográfica: Electrochimica Acta. 2017, 246: 951-962. doi:10.1016/j.electacta.2017.06.091
Resumen: The oxidation of hydroxyurea (H2NCONHOH, HU) at Au(100), Au(111) and Au(111)–25 nm thin film electrodes is studied spectroelectrochemically in perchloric acid solutions. HU, which in agreement with DFT results interacts weakly with the gold surfaces, oxidizes irreversibly at gold electrodes irrespective of the surface orientation. The in situ infrared external reflection spectra prove the formation of dissolved carbon dioxide and adsorbed cyanate as products of the HU electrooxidation reaction. A band at ca. 2230 cm−1 can be related both to dissolved isocyanic acid coming from the protonation of adsorbed cyanate or to nitrous oxide coming from the oxidation of hydroxylamine, which is formed (together with adsorbed cyanate) upon the chemical decomposition of hydroxyurea. ATR-SEIRAS experiments allow the observation of other adsorbate bands that can be tentatively ascribed to reaction intermediates that conserve the NCN skeleton and are bonded to the metal by the nitrogen atoms at near on-top positions. Bonding to the surface can be either unidentate or bidentate, involving covalent-type bonds or dative bonding through the lone pairs of the N atoms. Some of the signals of the experimental spectra, in particular those appearing around 1800 cm−1, can be assigned to the CO stretch of adsorbed intermediates having a nitrosyl group formed by oxidation of the NOH moiety (namely, adsorbed nitrosoformamide or its deprotonated form). The bands observed around 1650 cm−1 can correspond either to the NO stretching mode of the former species or to the CO stretching modes of adspecies conserving the NOH group.
Patrocinador/es: The authors acknowledge the funding by Ministerio de Economía y Competitividad through projectsCTQ2016-76221-P (AIE/FEDER, UE) and CTQ2016-76231-C2-2-R (AEI/FEDER, UE) and by the University of Alicante (VIGROB-263). William Cheuquepán is grateful for the award of a F.P.I. grant associated to project CTQ2009-13142.
URI: http://hdl.handle.net/10045/68000
ISSN: 0013-4686 (Print) | 1873-3859 (Online)
DOI: 10.1016/j.electacta.2017.06.091
Idioma: eng
Tipo: info:eu-repo/semantics/article
Derechos: © 2017 Published by Elsevier Ltd.
Revisión científica: si
Versión del editor: http://dx.doi.org/10.1016/j.electacta.2017.06.091
Aparece en las colecciones:INV - GEM - Artículos de Revistas

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