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Dos vías para la oxidación electrocatalítica del hidrógeno por un complejo de níquel bis ((difosfina) con aminas

Jenny Y Yang¹, Stuart E Smith, Tianbiao Liu

¹Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, P.O. Box 999, K2-57, Richland, Washington 99352, USA. j.yang@uci.edu

Journal of the American Chemical Society

|May 2, 2013

Resumen

Este estudio presenta un complejo de níquel como electrocatalizador para la oxidación del hidrógeno. La optimización de las condiciones con una base y agua específicas mejora significativamente la velocidad catalítica y reduce el sobrepotencial.

Área de la Ciencia:

Química Inorgánica La química inorgánica es la química inorgánica.
La electrocatálisis por electrocatálisis.
Química organometálica Química orgánica de los metales.

Sus antecedentes:

Los complejos de níquel bis ((difosfina) con aminas colgantes se exploran para aplicaciones catalíticas.
Se investiga el papel de la segunda esfera de coordinación en la catálisis.
La electrocatálisis de oxidación de hidrógeno es crucial para las tecnologías de conversión de energía.

Objetivo del estudio:

Para investigar el mecanismo de la oxidación del hidrógeno catalizado por un complejo de níquel bis ((difosfina).
Para determinar la viabilidad termodinámica de la adición de hidrógeno al complejo de níquel.
Para optimizar las condiciones catalíticas para una oxidación eficiente del hidrógeno.

Principales métodos:

Síntesis y caracterización de un complejo de níquel bis ((difosfina).
Estudios electroquímicos que incluyen mediciones del potencial redox.
Estudios cinéticos que varían las condiciones de la base y el disolvente.
Análisis termodinámico utilizando valores de pKa y potenciales redox.

Principales resultados:

El complejo de níquel actúa como un electrocatalizador para la oxidación del hidrógeno.
La adición de hidrógeno al complejo Ni (II) fue termodinámicamente favorable (-7,9 kcal mol (-1)).
La velocidad catalítica es sensible al tamaño de la base y a la presencia de agua.
La adición de agua facilita la desprotonación, reduciendo el sobrepotencial en 0,38 V.
En condiciones óptimas se obtuvo una frecuencia de rotación de 58 s.

Conclusiones:

El complejo de níquel es un electrocatalizador eficaz para la oxidación del hidrógeno.
La vía catalítica que implica la desprotonación previa es más eficiente.
Comprender el papel de la segunda esfera de coordinación y el disolvente es clave para la optimización del catalizador.

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