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Protein Film Infrared Electrochemistry Demonstrated for Study of H2 Oxidation by a [NiFe] Hydrogenase
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Caminos electrocatalíticos dependientes del potencial: control de la reactividad con pKa para la investigación
Eric S Rountree1, Jillian L Dempsey1
1Department of Chemistry, University of North Carolina , Chapel Hill, North Carolina 27599-3290, United States.
Journal of the American Chemical Society
|October 10, 2015
Resumen
Este estudio detalla los mecanismos de un catalizador de evolución de hidrógeno basado en níquel, revelando dos vías distintas (ECEC y EECC) que impulsan la reducción de protones. El análisis cinético aclaró los pasos clave en la producción de hidrógeno.
Área de la Ciencia:
- Química inorgánica
- La electroquímica
- Catálisis
Sus antecedentes:
- Los complejos de níquel son catalizadores prometedores para la evolución del hidrógeno.
- Comprender las vías mecanicistas de estos catalizadores es crucial para optimizar su eficiencia.
Objetivo del estudio:
- Realizar un análisis mecanicista detallado del catalizador de la evolución del hidrógeno [Ni ((P2 ((Ph) N2 ((Ph)) 2 ((CH2CN)) ] BF4]2.
- Para aclarar los distintos mecanismos (ECEC y EECC) involucrados en la catálisis de reducción de protones.
- Para determinar la cinética de los pasos elementales en la evolución del hidrógeno.
Principales métodos:
- Análisis electroquímico, incluida la voltametría cíclica.
- Espectroscopia con resolución de tiempo (flujo detenido).
- Mediciones cinéticas utilizando el desplazamiento del pico y el análisis del pie de la onda.
Principales resultados:
- El catalizador exhibe dos pares redox (Ni(II/I) a -0,83 V y Ni(I/0) a -1,03 V frente a Fc(+/0)).
- Se identificaron dos vías catalíticas distintas, ECEC y EECC, para la reducción de protones.
- Se determinaron las constantes de velocidad para la formación intermedia de níquel-hidruro (k1 = 1,2-6,5 × 10^6 M^-1 s^-1).
- Se monitoreó la reactividad del intermediario hidruro y de los intermediarios potenciales fuera del ciclo.
Conclusiones:
- El catalizador funciona a través de dos mecanismos distintos, ECEC y EECC, dependiendo del potencial aplicado.
- Los datos cinéticos proporcionan información sobre los pasos elementales de la evolución del hidrógeno.
- Los resultados sugieren la participación de un intermediario fuera del ciclo en el proceso catalítico.
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