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Tiolados de puente hemilabílicos como lanzaderas de protones en electrocatalizadores de producción de H2
Shengda Ding1, Pokhraj Ghosh1, Allen M Lunsford1
1Department of Chemistry, Texas A & M University , College Station, Texas 77843, United States.
Journal of the American Chemical Society
|August 20, 2016
Resumen
Los investigadores exploraron el acoplamiento protón-electrón y protón-hidruro en electrocatalizadores para la producción de hidrógeno. Los complejos de Ni-Fe y Fe-Fe muestran actividad, con mecanismos que implican la escisión de enlaces metal-azufre y orientaciones específicas para un acoplamiento eficiente.
Área de la Ciencia:
- Química inorgánica
- La electrocatálisis
- Química bioorgánica
Sus antecedentes:
- Las enzimas hidrogenasa son cruciales para el metabolismo biológico del hidrógeno.
- Los análogos sintéticos tienen como objetivo imitar los sitios activos de la hidrogenasa para la electrocatálisis.
- Comprender el acoplamiento protón-electrón y protón-hidruro es clave para una producción eficiente de H2.
Objetivo del estudio:
- Investigar las características que controlan el acoplamiento protón-electrón y protón-hidruro en electrocatalizadores sintéticos.
- Explorar las relaciones estructura-función en complejos bimetálicos inspirados por la [NiFe]-hidrogenasa.
- Identificar los electrocatalizadores activos para la producción de H2 y aclarar sus mecanismos de reacción.
Principales métodos:
- Síntesis de complejos ditiolatos bimetálicos (MN2S2) agregados con componentes de hierro.
- Análisis electroquímico para determinar la actividad catalítica para la producción de H2.
- Estudios computacionales para relacionar los potenciales electroquímicos con los parámetros mecanicistas.
Principales resultados:
- Se identificaron complejos bimetálicos de Ni-Fe' y Fe' como electrocatalizadores activos para la producción de H2.
- El mecanismo implica el ligando NO redox-activo para la captación de electrones y la escisión del enlace Fe-S (hemilabilidad).
- El acoplamiento eficiente requiere una orientación específica de hidruro y protón para la formación de H2, dependiendo de los niveles de redox.
Conclusiones:
- El ligando NO no inocente juega un papel en el almacenamiento de electrones, pero no en la formación de hidritos.
- La escisión del enlace Fe-S y la hemilabilidad del tiolato son cruciales para el transporte de protones y la generación de H2.
- La estabilidad del catalizador está influenciada por la composición del metal y el potencial de escisión de enlaces no deseados (por ejemplo, Fe'-S).
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