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La accesibilidad dependiente de la estructura de los sitios activos gobierna la actividad catalítica y la estabilidad
Yeonsu Kim1, Jeonghyeon Kim2, Sang-Il Choi2
1Department of Chemistry, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea.
Journal of the American Chemical Society
|December 29, 2025
Resumen
La comprensión de los catalizadores de óxido de iridio para la reacción de evolución del oxígeno (OER) es clave. La actividad del catalizador depende de la permeabilidad del electrolito, no del almacenamiento de carga, para diseños mejorados.
Área de la Ciencia:
- La electroquímica
- Ciencias de los materiales
- Catálisis
Sus antecedentes:
- Los óxidos de iridio son catalizadores cruciales para la reacción de evolución del oxígeno (OER) en medios ácidos.
- Optimizar la relación actividad-estabilidad de los óxidos de iridio requiere comprender sus influencias estructurales.
- Los desafíos actuales incluyen la identificación de variables de mecanismo de reacción en entornos complejos y degradantes.
Objetivo del estudio:
- Investigar la influencia estructural en la relación actividad-estabilidad de los óxidos de iridio en el OER ácido.
- Para cuantificar la reactividad transitoria de los intermediarios OER en diferentes superficies de óxido de iridio.
- Para aclarar los factores que rigen la catálisis OER en los sistemas de óxido de iridio.
Principales métodos:
- Se utilizó microscopía electroquímica de barrido de interrogación de superficie (SI-SECM) para sondear las superficies del catalizador.
- Las mediciones electroquímicas se realizaron en IrO amorfo y en IrO cristalino.
- Se cuantificó directamente la reactividad transitoria de los productos intermedios OER.
Principales resultados:
- La profundidad accesible por electrolitos de las capas del sitio activo muestra una dependencia de la estructura.
- Esta variación de profundidad controla la cinética de almacenamiento de carga y la catálisis OER.
- El almacenamiento efectivo de la carga tuvo un impacto mínimo en la barrera cinética OER.
Conclusiones:
- La actividad del catalizador de óxido de iridio en el OER se rige principalmente por la permeabilidad de los electrolitos.
- La permeabilidad del electrolito dicta el número de sitios activos accesibles.
- Este hallazgo contrasta con los modelos existentes que hacen hincapié en el almacenamiento de carga.
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