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Un intermetálico ordenado de alta entropía con múltiples sitios activos para la reacción de reducción de oxígeno

Tao Chen¹, Chunyu Qiu², Xinkai Zhang³

¹Beijing Key Laboratory of Theory and Technology for Advanced Batteries Materials, School of Materials Science and Engineering, Peking University, Beijing 100871, P.R. China.

Journal of the American Chemical Society

|December 28, 2023

Resumen

Los investigadores desarrollaron nanopartículas intermetálicas de alta entropía (PFCNCZ-HEI) de platino, hierro, cobalto, níquel y cobre ultrapequeñas. Estos catalizadores muestran una actividad de reacción de reducción de oxígeno significativamente mejorada para aplicaciones de celdas de combustible.

Área de la Ciencia:

Ciencias de los materiales
La electroquímica
Nanotecnología

Sus antecedentes:

El control de conjuntos multimetales a nivel atómico, especialmente en aleaciones de alta entropía (HEAs) con más de cinco elementos, presenta desafíos significativos.
El desarrollo de electrocatalizadores eficientes es crucial para el avance de tecnologías de energía limpia como las pilas de combustible.

Objetivo del estudio:

Sintetizar y caracterizar un catalizador de nanopartículas de alta entropía intermetálica (HEI) muy pequeño y bien ordenado.
Evaluar el rendimiento electrocatalítico del nuevo catalizador para la reacción de reducción de oxígeno (ORR).
Explorar el potencial de las IES en las pilas de combustible de membrana de intercambio de protones (PEMFC).

Principales métodos:

Utilizó una estrategia confinada en el espacio para sintetizar nanopartículas intermetálicas de alta entropía PtFeCoNiCuZn (PFCNCZ-HEI).
Se evaluó la actividad ORR de PFCNCZ-HEI mediante mediciones electroquímicas.
Montó un PEMFC utilizando PFCNCZ-HEI como catalizador de cátodo y evaluó su rendimiento.
Realizó cálculos teóricos para comprender la estructura electrónica y los sitios activos.

Principales resultados:

Alcanzó una actividad de masa ultra alta de 2,403 A mg_Pt^-1 a 0,90 V frente a RHE para el ORR, 19 veces mayor que el Pt/C comercial.
Se ha demostrado un PEMFC con una densidad de potencia de 1,4 W cm-2 y una potencia nominal normalizada en masa de 45 W mg pt-1.
Los cálculos teóricos indicaron electrones externos modulados en átomos de metales no nobles, creando múltiples centros activos.

Conclusiones:

Las nanopartículas PFCNCZ-HEI desarrolladas muestran una actividad electrocatalítica excepcional para el ORR.
La estrategia de síntesis confinada en el espacio es efectiva para crear nanopartículas HEI altamente ordenadas.
Este trabajo proporciona un diseño de catalizador prometedor para nanopartículas HEI altamente ordenadas en electrocatálisis.

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