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Covalencia Ce-O debilitada por el límite de grano a nanoescala y confinamiento superficial que aumenta
Weixin Zhao1, Wenyu Jia1, Jun Zhou1
1Institute of Industry Chemistry, College of Chemistry, Beijing University of Chemical Technology, Beijing 100029, China.
Journal of the American Chemical Society
|April 1, 2025
Resumen
Los límites de grano a nanoescala en los nanomateriales de óxido de cerio (CeO2) aumentan la reactividad superficial al debilitar los enlaces Ce-O. Esto mejora la oxidación catalítica del alcohol bencílico con una selectividad del 100%.
Área de la Ciencia:
- Ciencias de los materiales
- Química de las superficies
- Nanotecnología
Sus antecedentes:
- La reactividad del oxígeno de la celosía superficial es crucial para la catálisis de nanomateriales de óxido.
- La comprensión de los mecanismos electrónicos detrás de esta reactividad es limitada.
Objetivo del estudio:
- Elucidar el mecanismo electrónico mediante el cual los límites de grano a nanoescala (GB) mejoran la reactividad superficial de los nanomateriales de óxido de cerio (CeO2).
- Investigar el papel de los GB en el fomento de las reacciones de oxidación catalítica.
Principales métodos:
- Se han introducido GB en el CeO2 mediante la pirólisis de carbonato de cerio y precursores de formato.
- Se utilizaron estructuras de absorción de rayos X cercanas al borde (XANES) en los bordes O K y Ce L3.
- Se realizó la reducción programada por temperatura H2 (TPR) y la espectroscopia de Raman.
Principales resultados:
- Los GB reducen la covalencia de los enlaces Ce-O en CeO2.
- Esta disminución de la superposición orbital debilita el confinamiento en celosía de los átomos de oxígeno de la superficie.
- La actividad de salida de átomos de oxígeno superficiales mejorados promueve la formación de vacíos de oxígeno y la activación de O2.
Conclusiones:
- Los GB a nanoescala mejoran la reactividad de CeO2 al reducir la covalencia de la celosía, proporcionando una nueva perspectiva electrónica.
- Este mecanismo aumenta la formación de vacíos de oxígeno y la actividad catalítica, demostrada por la oxidación selectiva del alcohol bencílico al 100%.
- Los resultados ofrecen información sobre las relaciones estructura-función para mejorar el rendimiento catalítico de los nanomateriales.
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