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La espectroscopia ultra rápida revela una cascada de transferencia de electrones que mejora la evolución del

Kathryn L Corp¹, Cody W Schlenker¹

¹Department of Chemistry, University of Washington , Seattle, Washington 98195, United States.

Journal of the American Chemical Society

|May 25, 2017

Resumen

El nitruro de carbono exfoliado químicamente mejora la actividad fotocatalítica del nitruro de carbono grafítico (g-C3N4) para la generación de hidrógeno solar. Este efecto cooperativo mejora las tasas de evolución del hidrógeno al facilitar la transferencia de electrones, crucial para las soluciones energéticas sostenibles.

Área de la Ciencia:

Ciencias de los materiales
Fotocatálisis
Energía renovable

Sus antecedentes:

La generación de hidrógeno solar es clave para la energía sostenible.
El nitruro de carbono grafítico (g-C3N4) es un fotocatalizador prometedor para la división del agua.
Comprender la dinámica de transferencia de electrones de g-C3N4 es crucial para mejorar su eficiencia.

Objetivo del estudio:

Para investigar la dinámica de transferencia de electrones en los fotocatalizadores g-C3N4.
Aclarar el mecanismo detrás de la mayor actividad observada con el nitruro de carbono exfoliado.
Establecer normas de diseño para mejorar el rendimiento de los fotocatalizadores basados en carbono.

Principales métodos:

Espectroscopia de absorción transitorio de femtosegundos (TA) en el espectro visible y el infrarrojo cercano.
Fabricación de un fotocatalizador compuesto con g-C3N4 a granel y nitruro de carbono exfoliado químicamente.
Medición de las tasas de evolución del hidrógeno fotocatalítico.

Principales resultados:

Un compuesto de g-C3N4 y nitruro de carbono exfoliado mostró una casi duplicación de la actividad fotocatalítica (2050 a 3810 μmol h−1 g−1).
La espectroscopia TA reveló una rápida transferencia de electrones desde g-C3N4 al nitruro de carbono exfoliado, acercándose al límite de difusión.
La transferencia de electrones redujo significativamente el tiempo de desintegración de los electrones fotogenerados en g-C3N4 de 4,1 ns a 660 ps.

Conclusiones:

La mayor actividad es el resultado de un efecto cooperativo: generación de carga en g-C3N4 seguida de transferencia de electrones al nitruro de carbono exfoliado.
El nitruro de carbono exfoliado actúa como un sumidero de electrones, mejorando la separación de cargas y la eficiencia fotocatalítica.
Este estudio proporciona información crítica sobre el control de la dinámica de separación de cargas para los fotocatalizadores avanzados basados en carbono.

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