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Ingeniería de valencia a través de sustitución atómica selectiva en sitios tetraédricos en óxido de espinel para
Yan Liu1, Yiran Ying1, Linfeng Fei1
1Department of Applied Physics , The Hong Kong Polytechnic University , Hung Hom, Kowloon , Hong Kong , China.
Journal of the American Chemical Society
|April 25, 2019
Resumen
La adición de hierro a los óxidos de níquel-cobalto aumenta significativamente el rendimiento de la reacción de evolución del oxígeno (OER). Este nuevo material catalizador alcanza potenciales excesivamente bajos, superando un obstáculo importante para las aplicaciones prácticas de OER.
Área de la Ciencia:
- La electroquímica
- Ciencias de los materiales
- Catálisis
Sus antecedentes:
- Los altos sobrepotenciales limitan el uso práctico de los óxidos de metales de transición en las reacciones de evolución del oxígeno (OER).
- La optimización de la estructura electrónica y las energías de adsorción es crucial para que los catalizadores OER sean eficientes.
Objetivo del estudio:
- Investigar el efecto del dopaje de hierro en el rendimiento de los óxidos de nicoespinela.
- Comprender la preferencia del sitio de Fe en los óxidos de NiCo y su impacto en la actividad catalítica.
Principales métodos:
- Cálculos teóricos para determinar la favorabilidad energética del Fe en sitios tetraédricos.
- Síntesis de catalizadores de óxido de NiCoFe.
- Espectroscopia de absorción de rayos X (XAS) para analizar el sitio de dopaje de Fe y los estados de oxidación.
Principales resultados:
- El Fe ocupa preferentemente sitios tetraédricos en los óxidos de espinela de NiCo.
- Este dopaje induce Ni3+ y Co2+ en sitios octaédricos, mejorando la actividad OER.
- El catalizador de óxido de NiCoFe logró un sobrepotencial ultrabajo de 201 mV cm-2 a 10 mA cm-2 y una pendiente Tafel de 39 mV dec-1.
Conclusiones:
- El dopaje de Fe en óxidos de espinela de NiCo es una estrategia eficaz para mejorar el rendimiento de la OER.
- La ocupación preferente de los sitios tetraédricos por Fe optimiza la estructura electrónica para la catálisis superior.
- El catalizador de óxido de NiCoFe desarrollado supera a los catalizadores de última generación basados en Ni-Co.
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