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Energías de enlace de hidrógeno y agua dependientes del pH en superficies de platino detectadas directamente a través

Shangqian Zhu¹, Xueping Qin¹, Yao Yao¹

¹Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.

Journal of the American Chemical Society

|April 21, 2020

Resumen

Este estudio revela cómo el pH afecta las reacciones de hidrógeno en las superficies de platino (Pt). Descubrimos que el aumento del pH debilita la unión de hidrógeno y agua, aclarando preguntas de décadas de antigüedad en electrocatálisis.

Área de la Ciencia:

La electroquímica
Ciencias de la superficie
Espectroscopia

Sus antecedentes:

La cinética dependiente del pH de la evolución del hidrógeno y las reacciones de oxidación en las superficies de platino (Pt) sigue siendo poco conocida.
Estas reacciones son cruciales para las tecnologías de conversión de energía, incluidas las pilas de combustible y los electrolizadores.

Objetivo del estudio:

Investigar directamente el comportamiento vibratorio del hidrógeno adsorbido y el agua interfacial en superficies Pt en un amplio rango de pH.
Para aclarar los orígenes de la cinética dependiente del pH en las reacciones de hidrógeno en Pt.

Principales métodos:

Se utilizó la espectroscopia de absorción de infrarrojos mejorada por superficie (SEIRAS).
Números de ondas vibratorias monitoreados de hidrógeno adsorbido y moléculas de agua interfaciales.
Superficies Pt estudiadas en soluciones que abarcan un pH de 1,1 a 12,9.

Principales resultados:

Se han medido con éxito los cambios dependientes del pH en las fuerzas de unión del hidrógeno y el agua.
Se observó un debilitamiento monótono de la unión de hidrógeno y agua a medida que aumentaba el pH de la solución.
Correlacionó estos cambios de unión con los entornos de interfaz electroquímica alterados.

Conclusiones:

El debilitamiento observado de la unión es un factor clave que influye en la cinética de reacción de hidrógeno dependiente del pH en Pt.
Proporciona evidencia directa del papel significativo de los entornos interfaciales en la electrocatálisis.
Ofrece nuevos conocimientos sobre los mecanismos fundamentales de las reacciones de hidrógeno en el platino.

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