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Modelos cooperativos de Fe-N₄ y Sn-N para una electrorreducción de oxígeno más duradera y activa en las pilas de

Fan Xia^1,2, Bomin Li¹, Bowen An¹

¹Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States.

Journal of the American Chemical Society

|December 2, 2024

Resumen

Este estudio introduce sitios atómicos de estaño-nitrógeno para mejorar los electrocatalizadores de hierro-nitrógeno-carbono para pilas de combustible. Los nuevos sitios mejoran la durabilidad y la actividad al estabilizar los sitios de hierro y alterar el mecanismo de reacción de reducción de oxígeno.

Área de la Ciencia:

Ciencias de los materiales
La electroquímica
Catálisis

Sus antecedentes:

Los electrocatalizadores libres de metales del grupo del platino (PGM) son cruciales para las pilas de combustible de membrana de intercambio de protones (PEMFC).
Los carbonos porosos con fracciones metal-nitrógeno-carbono (M-N-C) se enfrentan a desafíos en actividad y durabilidad.

Objetivo del estudio:

Mejorar la durabilidad y la actividad de los electrocatalizadores Fe-N-C para los PEMFC.
Modular el entorno local de los sitios Fe-N4 utilizando sitios atómicos Sn-N.

Principales métodos:

Síntesis de catalizadores de Fe/Sn-PNC.
Caracterización de la estructura del catalizador y de los sitios activos.
Evaluación electroquímica de la actividad y durabilidad de la reacción de reducción de oxígeno (ORR).

Principales resultados:

Descubrimiento de un sitio único de D3 SnN-FeII N4 con Sn-N y Fe-N4 atómicamente dispersos.
Mejor estabilidad frente a la desmetalización y una frecuencia de rotación ORR significativamente mayor.
Cambio en el mecanismo ORR a una vía de doble ubicación, reduciendo el potencial de escisión de enlaces O-O y la formación de peróxido.
Mayor durabilidad del catalizador en conjuntos de electrodos de membrana.

Conclusiones:

Los sitios atómicos de Sn-N estabilizan efectivamente los electrocatalizadores de Fe-N-C.
El nuevo sitio D3 y el mecanismo de reacción modificado conducen a una actividad y durabilidad superiores.
Este enfoque ofrece una estrategia prometedora para el desarrollo de electrocatalizadores avanzados sin PGM para pilas de combustible.

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