Artículo
Structural and chemical reactivity modifications of a cobalt perovskite induced by Sr-substitution. An in situ XAS study
Autor/es | Hueso Martos, José Luis
Holgado Vázquez, Juan Pedro Pereñíguez Rodríguez, Rosa María González de la Cruz, Víctor M. Caballero Martínez, Alfonso |
Departamento | Universidad de Sevilla. Departamento de Química Inorgánica |
Fecha de publicación | 2015 |
Fecha de depósito | 2017-09-19 |
Publicado en |
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Resumen | LaCoO3 and La0.5Sr0.5CoO3-δ perovskites have been studied by in situ Co K-edge XAS. Although the partial substitution of La(III) by Sr(II) species induces an important increase in the catalytic oxidation activity and ... LaCoO3 and La0.5Sr0.5CoO3-δ perovskites have been studied by in situ Co K-edge XAS. Although the partial substitution of La(III) by Sr(II) species induces an important increase in the catalytic oxidation activity and modifies the electronic state of the perovskite, no changes could be detected in the oxidation state of cobalt atoms. So, maintaining the electroneutrality of the perovskite requires the generation of oxygen vacancies in the network. The presence of these vacancies explains that the substituted perovskite is now much more reducible than the original LaCoO3 perovskite. As detected by in situ XAS, after a consecutive reduction and oxidation treatment, the original crystalline structure of the LaCoO3 perovskite is maintained, although in a more disordered state, which is not the case for the Sr doped perovskite. So, the La0.5Sr0.5CoO3-δ perovskite submitted to the same hydrogen reduction treatment produces metallic cobalt, while as determined by in situ XAS spectroscopy the subsequent oxidation treatment yields a Co(III) oxide phase with spinel structure. Surprisingly, no Co(II) species are detected in this new spinel phase. |
Agencias financiadoras | Ministerio de Economía y Competitividad (MINECO). España |
Identificador del proyecto | ENE2011-24412 |
Cita | Hueso Martos, J.L., Holgado Vázquez, J.P., Pereniguez Rodríguez, R.M., González de la Cruz, V.M. y Caballero Martínez, A. (2015). Structural and chemical reactivity modifications of a cobalt perovskite induced by Sr-substitution. An in situ XAS study. Materials Chemistry and Physics, 151, 21-33. |
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