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Desentrañar un proceso de transferencia simultánea de dos electrones de un semiconductor a un catalizador molecular

Yuxing Xu^1,2,3, Yun Ye^1,2,3, Taifeng Liu^1,2,3

¹State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian National Laboratory for Clean Energy, Dalian 116023, China.

Journal of the American Chemical Society

|August 17, 2016

Resumen

Investigando la transferencia de electrones en la fotocatálisis híbrida, este estudio revela que las condiciones de alto pH favorecen una transferencia directa de dos electrones del sulfuro de cadmio (CdS) al cobalto (CoPy) para la evolución del hidrógeno. Este hallazgo mejora la comprensión de las interacciones entre semiconductores y catalizadores.

Área de la Ciencia:

Fotocatálisis
Mecanismos de transferencia de electrones
Materiales híbridos

Sus antecedentes:

La transferencia de electrones de semiconductor a catalizador molecular es crucial para la evolución del hidrógeno fotocatalítico.
Comprender la cinética y la termodinámica de estos procesos es clave para optimizar los sistemas híbridos.
Los catalizadores moleculares basados en cobalto y los semiconductores de sulfuro de cadmio (CdS) se estudian ampliamente para la producción de H2.

Objetivo del estudio:

Investigar las vías de transferencia de electrones en un sistema fotocatalítico híbrido [Co(III)) ((dmgH) 2PyCl] (CoPy) y CdS.
Para aclarar el mecanismo de la evolución del hidrógeno en condiciones de pH variables.
Para determinar si la transferencia de electrones se produce a través de procesos de un solo paso de dos electrones o de dos pasos de un electrón.

Principales métodos:

Se utilizó un modelo de sistema fotocatalítico híbrido compuesto por CoPy y CdS.
Se han realizado estudios termodinámicos y cinéticos en diferentes condiciones de pH, centrándose en el pH alto (13,5).
Analizó las especies intermedias formadas durante el proceso fotocatalítico.

Principales resultados:

A un pH alto (13,5), la evolución del hidrógeno fotocatalítico es impulsada predominantemente por una transferencia simultánea de dos electrones de CdS fotoirradiado a Co(III) Py.
Esta vía conduce a la formación de un intermediario Co ((I) Py.
Un proceso de transferencia de un electrón en dos pasos sucesivos es termodinámicamente menos favorable en estas condiciones.

Conclusiones:

El estudio proporciona información crítica sobre la dinámica de transferencia de carga entre semiconductores y catalizadores moleculares en sistemas híbridos.
Los hallazgos ponen de relieve la importancia del control del pH para dirigir las vías de transferencia de electrones para procesos multielectrónicos eficientes.
Este trabajo abre nuevas vías para diseñar y optimizar fotocatalizadores híbridos para la evolución del hidrógeno y otras transformaciones multielectrónicas.

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