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La corrosión inducida por halógenos del platino
Enrico Doná1, Michael Cordin, Clemens Deisl
1Institute of Physical Chemistry, University of Innsbruck, Innrain 52a, A-6020 Innsbruck, Austria.
Journal of the American Chemical Society
|February 11, 2009
Resumen
La interacción del cloro con las superficies de platino (Pt) causa la erosión de la superficie y la formación de PtCl4). El recocido repara los defectos, creando una capa adicional ordenada similar a los resultados de la deposición de electrolitos.
Área de la Ciencia:
- Ciencias de la superficie Ciencias de la superficie.
- Química de los materiales Química de los materiales
- Química Física es la química física.
Sus antecedentes:
- Comprender las interacciones adsorbado-superficie es crucial para la catálisis y la ciencia de los materiales.
- Las superficies de platino se utilizan ampliamente en la catálisis, por lo que su reactividad con halógenos es un área de investigación clave.
Objetivo del estudio:
- Para investigar la interacción del cloro (Cl) con la superficie de platino (Pt) en condiciones de ultra alto vacío (UHV).
- Para dilucidar los cambios estructurales y químicos que se producen durante la adsorción de Cl y la compresión en Pt{110}.
Principales métodos:
- Microscopía de túnel de barrido (STM) para imágenes de superficie a escala atómica.
- Difracción de electrones de baja energía (LEED) para el análisis de la estructura de la superficie.
- Desorción programada por temperatura (TPD) para estudiar la cinética de la desorción.
- Cálculos de la teoría funcional de la densidad (DFT) para conocimientos teóricos.
Principales resultados:
- Hasta 0,5 monocapa (ML) de Cl forman una estructura de adsorbado estable en el Pt110).
- La compresión de Cl a cubiertas más altas induce la erosión del átomo Pt y forma pentámeros PtCl.
- El recocido repara los defectos de la superficie Pt y forma una capa adicional PtCl(4)/Cl/Pt(110) ordenada por largo alcance.
- La coadsorción con CO inicia la formación de PtCl(4) sin productos volátiles.
- El bromo (Br) muestra una menor actividad de corrosión, dejando la superficie Pt intacta.
Conclusiones:
- El cloro altera significativamente la estructura de la superficie de Pt{\displaystyle Pt{\displaystyle Pt{\text{1}}} , lo que lleva a la formación de defectos y a las especies de Pt{\text{\text{Cl}}} .
- La estructura adyacente observada después del recocido es análoga a la formada por la deposición de electrolitos.
- El estudio comparativo con bromo pone de relieve la reactividad diferencial de los halógenos con superficies de platino.
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