Artículo
Surface oxygen vacancies in gold based catalysts for CO oxidation
Autor/es | Romero Sarria, Francisca
Plata Ramos, José Javier Laguna Espitia, Oscar Hernando Márquez Cruz, Antonio Marcial Centeno Gallego, Miguel Ángel Fernández Sanz, Javier Odriozola Gordón, José Antonio |
Departamento | Universidad de Sevilla. Departamento de Química Inorgánica Universidad de Sevilla. Departamento de Química Física |
Fecha de publicación | 2014 |
Fecha de depósito | 2017-03-21 |
Publicado en |
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Resumen | Experimental catalytic activity measurements, Diffuse Reflectance Infrared Fourier Spectroscopy, and Density Functional Theory calculations are used to investigate the role and dynamics of surface oxygen vacancies in the ... Experimental catalytic activity measurements, Diffuse Reflectance Infrared Fourier Spectroscopy, and Density Functional Theory calculations are used to investigate the role and dynamics of surface oxygen vacancies in the CO oxidation with O2 catalyzed by Au nanoparticles supported on a Y-doped TiO2 catalyst. Catalytic activity measurements show that the CO conversion is improved in a second cycle of reaction if the reactive flow is composed by CO and O2 (and inert) while if water is present in the flow, the catalyst shows a similar behaviour in two successive cycles. DRIFTS-MS studies indicate the occurrence of two simultaneous phenomena during the first cycle in dry conditions: the surface is dehydroxylated and a band at 2194 cm-1 increases (proportionally to the number of surface oxygen vacancies). Theoretical calculations were conducted in order to explain these observations. On one hand, the calculations show that there is a competition between gold nanoparticles and OH to occupy the surface oxygen vacancies and that the adsorption energy of gold on these sites increases as the surface is being dehydroxylated. On another hand, these results evidence that a strong electronic transfer from the surface to the O2 molecule is produced after its adsorption on the Au/TiO2 perimeter interface (activation step), leaving the gold particle in a high oxidation state. This explains the appearance of a band at a wavenumber unusually high for the CO adsorbed on oxidized gold particles (2194 cm-1) when O2 is present in the reactive flow. These simultaneous phenomena indicate that a gold redispersion on the surface occurs under reactive flow in dry conditions generating small gold particles very actives at low temperature. This fact is notably favoured by the presence of surface oxygen vacancies that improve the surface dynamics. The obtained results suggest that the reaction mechanism proceeds through the formation of a peroxo-like complex formed after the electronic transfer from the surface to the gas molecule. |
Agencias financiadoras | Ministerio de Economía y Competitividad (MINECO). España European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER) |
Identificador del proyecto | info:eu-repo/grantAgreement/MINECO/MAT2012-31526
info:eu-repo/grantAgreement/MINECO/CSD2008-0023 info:eu-repo/grantAgreement/MINECO/ENE2012-37431-C03-01 |
Cita | Romero Sarria, F., Plata Ramos, J.J., Laguna Espitia, O.H., Márquez Cruz, A.M., Centeno Gallego, M.Á., Fernández Sanz, J. y Odriozola Gordón, J.A. (2014). Surface oxygen vacancies in gold based catalysts for CO oxidation. RSC Advances: An International Journal to Further the Chemical Sciences, 4, 13145-13152. |
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