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Evolución del hidrógeno electrocatalítico en condiciones acuosas ácidas y estudios mecánicos de un catalizador
1Department of Chemistry, University of California , Irvine, California 92697, United States.
Journal of the American Chemical Society
|July 15, 2016
Resumen
Un complejo de níquel estable, [Ni(DHMPE) 2+, cataliza eficientemente la reacción de evolución del hidrógeno (HER) en condiciones ácidas. Este catalizador homogéneo demuestra una alta estabilidad y actividad, lo que permite estudios mecanicistas detallados para mejorar la electrocatálisis.
Área de la Ciencia:
- La electroquímica
- Catálisis
- Química organometálica
Sus antecedentes:
- La reacción de evolución del hidrógeno (HER) es crucial para las tecnologías de energía sostenible.
- El desarrollo de catalizadores homogéneos estables y eficientes para el HER, especialmente en medios ácidos, sigue siendo un desafío importante.
- Los complejos de níquel ofrecen un potencial como alternativas rentables a los catalizadores de metales preciosos.
Objetivo del estudio:
- Para indicar la actividad electrocatalítica de un complejo de níquel soluble en agua, [Ni(DHMPE) 2+, para el HER a pH 1.
- Investigar la estabilidad y las vías mecanicistas de este catalizador de níquel en condiciones ácidas.
- Permitir estudios mecanicistas detallados a través de la estabilidad del compuesto y los intermedios catalíticos.
Principales métodos:
- Electrocatálisis mediante el uso de un complejo de níquel ([Ni(DHMPE) 2+) a pH 1.
- Cuantificación del complejo antes y después de la electrólisis prolongada (18 horas o más).
- Análisis de parámetros termodinámicos para la transferencia de electrones y protones.
- Identificación espectroscópica de los intermediarios de las reacciones.
Principales resultados:
- El complejo [Ni(DHMPE) 2+ exhibe una alta actividad catalítica (k_obs ~ 10^3 s^-1) y una eficiencia Faradaic para HER.
- Se observó una descomposición insignificante del catalizador después de más de 18 horas de electrólisis, lo que indica una excelente estabilidad en condiciones ácidas.
- Los estudios mecanicistas detallados permitieron la identificación espectroscópica de los productos intermedios clave.
Conclusiones:
- El complejo de níquel soluble en agua [Ni(DHMPE) 2+ es un catalizador homogéneo altamente estable y activo para la reacción de evolución del hidrógeno a pH 1.
- La estabilidad observada en condiciones ácidas es rara para los catalizadores de HER homogéneos.
- Los estudios mecánicos sugieren una vía que implica la reducción de dos electrones, seguida de pasos de protonación secuenciales.
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