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Optical Trapping of Nanoparticles
Published on: January 15, 2013
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Equilibrio lento entre estados de trampa espectroscópicamente distintos en nanopartículas reducidas de TiO
Jennifer L Peper1, David J Vinyard1, Gary W Brudvig1
1Department of Chemistry, Yale University , New Haven, Connecticut 06520-8107, United States.
Journal of the American Chemical Society
|February 9, 2017
Resumen
Comprender las trampas de electrones en las nanopartículas de dióxido de titanio (TiO2) es clave para las aplicaciones de energía solar. Los investigadores encontraron dos trampas de electrones distintas que cambian lentamente, lo que sugiere modificaciones estructurales en el TiO2 reducido.
Área de la Ciencia:
- Ciencias de los materiales
- Nanotecnología
- La fotoquímica
Sus antecedentes:
- El dióxido de titanio a nanoescala (TiO2) es crucial para la conversión de energía solar y la fotocatálisis.
- Comprender el comportamiento del portador de carga en TiO2 es esencial para optimizar estas aplicaciones.
Objetivo del estudio:
- Investigar la naturaleza de las trampas de electrones en las nanopartículas acuosas de TiO2 irradiadas por rayos UV.
- Caracterizar los distintos estados de trampa de electrones y su dinámica de interconversión.
Principales métodos:
- Espectroscopia de resonancia paramagnética de electrones (EPR)
- Las espectroscopias ópticas
- Irradiación UV de las nanopartículas coloidales de TiO2 en el metanol
Principales resultados:
- Se identificaron y caracterizaron dos tipos distintos de trampas de electrones.
- Las poblaciones relativas de estas trampas dependen de la temperatura, con una pequeña diferencia de energía (ΔH° = 3,0 ± 0,6 kcal/mol).
- La interconversión entre trampas se produce lentamente (minutos a horas) entre 0 y 50 °C, lo que implica cambios estructurales o estequiométricos.
Conclusiones:
- La modificación estructural lenta acompaña a los cambios en la ocupación del estado de la trampa en los sistemas de TiO2 reducido.
- Este fenómeno es probablemente general para el TiO2 en estados termodinámicos o fotostationarios.
- La consideración de estas dinámicas lentas es importante para el diseño de dispositivos eficaces basados en TiO2.
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