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Oxidación de agua por lambda-MnO2: catálisis por el subgrupo cúbico Mn4O4 obtenido por deslitificación de espinela
David M Robinson1, Yong Bok Go, Martha Greenblatt
1Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA.
Journal of the American Chemical Society
|August 3, 2010
Resumen
La deslitización del óxido de litio manganeso nanocristalino (LiMn(2) O(4) produce dióxido de lambda-manganeso activo (lambda-MnO(2) para la oxidación del agua. La lambda-MnO2 a nanoescala exhibe una actividad catalítica superior en comparación con las partículas más grandes.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- La catálisis por catálisis.
- La electroquímica es electroquímica.
Sus antecedentes:
- El óxido de litio-manganeso (LiMn{2}O{4}) es un material prometedor en el almacenamiento de energía.
- La oxidación del agua es un proceso crítico para las tecnologías de energía renovable.
- La actividad catalítica de los óxidos de manganeso para la oxidación del agua es de gran interés.
Objetivo del estudio:
- Para investigar la actividad catalítica de oxidación del agua del litio deslitiado LiMn{2}O{4}, específicamente lambda-Mn{2}O{2).
- Para comparar el rendimiento catalítico de nanocristalino lambda-MnO(2) con materiales de mayor tamaño de partícula.
- Comprender el papel de la morfología a nanoescala en la catálisis de la oxidación del agua.
Principales métodos:
- Síntesis de nanocristalino LiMn(2)O(4) a través de la vía del citrato.
- Delitización de LiMn(2)O(4) utilizando ácido nítrico diluido para formar lambda-MnO(2).
- Estudios fotoquímicos de oxidación del agua utilizando el sistema [Ru(2+) ((2,2'-bpy) ((3)) ]/persulfato a un pH de 5.8.
Principales resultados:
- La deslitificación de LiMn(2)O(4) mantuvo la estructura de espinela, formando lambda-MnO(2).
- Los núcleos cúbicos de MnO4 en lambda-MnO2 actúan como sitios activos para la oxidación del agua.
- En la escala nanométrica lambda-MnO2 demostró una frecuencia de rotación significativamente mayor (3 x 10-5 s-1) en comparación con la de tamaño micrométrico lambda-MnO2 (5 x 10-6 s-1).
Conclusiones:
- La nanocristalina lambda-MnO2 derivada de LiMn2O4 es un catalizador eficaz para la oxidación del agua.
- El método de síntesis y el tamaño de partícula resultante influyen significativamente en la actividad catalítica.
- Este estudio pone de relieve el potencial de las nanoestructuras de óxido de manganeso a medida para una división eficiente del agua.
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