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Seguimiento de las configuraciones estructurales y electrónicas de un catalizador de reducción de protones de cobalto
Dooshaye Moonshiram, Carolina Gimbert-Suriñach1, Alexander Guda2
1Institute of Chemical Research of Catalonia (ICIQ), Barcelona Institute of Science and Technology , Avinguda Països Catalans 16, 43007 Tarragona, Spain.
Journal of the American Chemical Society
|July 26, 2016
Resumen
Este estudio utilizó la espectroscopia de absorción transitoria de rayos X (X-TAS) para investigar un catalizador de cobalto para la evolución del hidrógeno. La investigación identificó los principales intermediarios de cobalto y señaló la protonación de las especies CoI como el paso que limita la velocidad para los catalizadores mejorados de celdas de combustible.
Área de la Ciencia:
- Fotocatálisis y electrocatálisis
- Química de coordinación
- Espectroscopia y cinética de la reacción
Sus antecedentes:
- El desarrollo de catalizadores eficientes para la evolución del hidrógeno es crucial para las tecnologías de energía renovable como las pilas de combustible de hidrógeno.
- Los complejos basados en cobalto son candidatos prometedores para la catálisis de la evolución del hidrógeno debido a sus propiedades electrónicas sintonizables.
- La comprensión del mecanismo de reacción y la identificación de los intermedios transitorios son clave para la optimización del catalizador.
Objetivo del estudio:
- Elucidar el mecanismo in situ de la evolución del hidrógeno inducida por la luz catalizada por un complejo de cobalto macrocíclico.
- Identificar y caracterizar los intermedios transitorios de cobalto formados durante el ciclo catalítico mediante espectroscopia de resolución temporal.
- Para determinar el paso que limita la velocidad de la reacción de evolución del hidrógeno catalizada por el complejo de cobalto.
Principales métodos:
- Se utilizó la espectroscopia de absorción transitoria de rayos X (X-TAS) para sondear los cambios electrónicos y estructurales del catalizador en tiempo real.
- Se utilizó la estructura de absorción de rayos X cerca del borde (XANES) y la estructura fina de absorción de rayos X extendida (EXAFS) para el análisis estructural detallado.
- Cálculos de la teoría funcional de densidad integrada (DFT), incluidos los métodos de órbitales moleculares (DFT-MO) y de diferencias finitas (FDM), para la asignación de especies y el modelado mecanicista.
Principales resultados:
- Identificó la formación in situ de un intermediario de Co2 distorsionado con una cinética de transferencia de electrones de 51 ns en un sistema binario.
- Se observó la formación transitoria de una especie cuadrada de Co ((I) en nanosegundos en el sistema fotocatalítico completo, que se descompone en la escala de tiempo de microsegundos.
- Se ha determinado que la protonación del intermediario Co (I) es el paso que limita la velocidad en el ciclo catalítico.
Conclusiones:
- Estableció una vía mecanicista integral para la reacción de evolución del hidrógeno catalizada por el complejo de cobalto macrocíclico.
- Proporcionó una visión cinética única en el ciclo catalítico, crucial para el diseño de catalizadores avanzados para pilas de combustible de hidrógeno.
- El estudio destaca la importancia de comprender las especies transitorias y la cinética de la reacción para el desarrollo del catalizador.
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