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Grupos funcionales que contienen oxígeno en nanotubos de carbono de pared única: NEXAFS y estudios espectroscópicos

A Kuznetsova¹, I Popova, J T Yates

¹Department of Chemistry, Surface Science Center, University of Pittsburgh, Pennsylvania 15260, USA.

Journal of the American Chemical Society

|October 25, 2001

Resumen

Los nanotubos oxidados de pared única (SWNT) se analizaron utilizando NEXAFS. La purificación ácida crea grupos carbonilo y éter, que se eliminan por calentamiento, restaurando la estructura SWNT.

Área de la Ciencia:

Ciencia de los materiales Ciencia de los materiales.
Nanotecnología La nanotecnología es la nanotecnología.
Química de las superficies.

Sus antecedentes:

Los nanotubos de pared única (SWNT) son nanomateriales cruciales con diversas aplicaciones.
La funcionalidad de la superficie tiene un impacto significativo en las propiedades y el rendimiento de SWNT.
Comprender los estados de oxidación es clave para controlar el comportamiento de SWNT.

Objetivo del estudio:

Para caracterizar grupos funcionales oxidados en SWNTs producidos por vaporización láser de plasma (PLV) utilizando NEXAFS.
Para comparar los PLV-SWNTs oxidados con los HiPco SWNTs.
Para investigar la estabilidad térmica de los grupos funcionales oxidados en SWNTs.

Principales métodos:

Espectroscopia de estructura fina de absorción de rayos X de borde cercano (NEXAFS) en el borde C-K.
Espectroscopia de Raman Espectroscopia de Raman Espectroscopia de Raman Espectroscopia de Raman Espectroscopia de Raman Espectroscopia de Raman Espectroscopia de Raman Espectroscopia de Raman Espectroscopia de Raman Espectroscopia de Raman Espectroscopia de Raman Espectroscopia de Raman Espectroscopia de Raman
Espectroscopia infrarroja (citada para su comparación).

Principales resultados:

La purificación ácida de PLV-SWNT introduce grupos carbonilo (C=O) y éter (C-O-C), evidenciados por las resonancias pi*(CO) y sigma*(CO) NEXAFS.
El calentamiento de PLV-SWNTs a 500-600 K reduce la intensidad pi*(CO); el calentamiento a 1073 K elimina las resonancias sigma*(CO) a medida que los grupos C-O-C se descomponen.
Los espectros de Raman confirman que la estructura tubular SWNT permanece intacta después del calentamiento a 1073 K.
Los SWNT de HiPco, sin tratamiento ácido, muestran una oxidación mínima y no hay resonancias NEXAFS detectables para estos grupos.
Los PLV-SWNT recocidos exhiben espectros NEXAFS similares a los SWNT de HiPco.

Conclusiones:

El tratamiento con ácido crea grupos funcionales oxidado específicos en SWNTs.
Estos grupos funcionales pueden ser removidos térmicamente sin dañar la estructura SWNT.
NEXAFS es una poderosa herramienta para identificar y cuantificar especies oxidadas en SWNTs.

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