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首页> 外文期刊>Journal of photochemistry and photobiology, C. Photochemistry reviews >Ultrafast plasmon induced electron injection mechanism in gold-TiO_2 nanoparticle system
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Ultrafast plasmon induced electron injection mechanism in gold-TiO_2 nanoparticle system

机译：金-TiO_2纳米粒子系统中超快等离激元诱导的电子注入机理

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摘要

To study plasmon-induced charge transfer mechanism between an excited gold nanoparticle (NP) and a TiO_2 NP, which can be applied to solar cell and photocatalyst technologies, ultrafast femtosecond visible-pump/infrared-probe transient absorption spectroscopy was utilized to explore charge separation and recombination dynamics in gold-TiO_2 NP systems. In this review, our recent works are summarized. TiO_2 NPs of different diameters were chosen as electron acceptors for a gold NP donor with a 10-nm diameter. Electron transfer from gold NPs to the conduction band of TiO_2 was observed by the transient absorption of electrons in the conduction band of TiO_2 at 3440nm after optical excitation of the surface plasmon band of gold NPs. By using a reference of Ru-complex dye sensitized TiO_2 film, the occurrence of ultrafast electron injection from gold NPs to TiO_2 NP film was clearly proved. It was found that electron injection was completed within 50fs and the electron injection yield reached 20-50% under 550nm excitation. The excitation wavelength dependence between 400 and 680nm suggested that there were two pathways for the injection: one was through direct electron-hole generation, and the other seemed to relate to enhanced electric field by plasmon. The charge recombination decay within 1.5ns was nonexponential and strongly dependent on the particle diameter of TiO_2. Larger TiO_2 particles resulted in longer charge recombination times because of the longer diffusion length of electrons in TiO_2 particles. Also, two-photon absorption cross-section of the 10-nm gold NP at a near-infrared wavelength (1200nm) was estimated to be as large as 10~8GM (1GM=10~(-50)cm~4sphoton~(-1)molecule~(-1)).
机译：为了研究等离激元诱导的纳米金和TiO_2 NP之间的电荷转移机理，并将其应用于太阳能电池和光催化剂技术，利用超快飞秒可见泵/红外探针瞬态吸收光谱法研究电荷分离-TiO_2 NP体系的合成和复合动力学在这篇评论中，总结了我们最近的工作。选择不同直径的TiO_2 NPs作为直径为10 nm的金NP供体的电子受体。在光激发金纳米粒子的表面等离子体激元带后，通过在3440nm处的TiO_2导带中电子的瞬态吸收，观察到电子从金纳米粒子转移到TiO_2的导带。通过使用Ru络合物染料敏化的TiO_2薄膜作为参考，清楚地证明了从金纳米粒子向TiO_2纳米粒子薄膜的超快电子注入。发现在550nm激发下电子注入完成，并且在550nm激发下电子注入产率达到20-50％。激发波长在400至680nm之间的依赖性表明注入有两种途径：一种是通过直接产生电子空穴，另一种似乎与等离子体激元增强的电场有关。 1.5ns内的电荷复合衰减是非指数的，并且强烈依赖于TiO_2的粒径。较大的TiO_2颗粒会导致更长的电荷重组时间，因为电子在TiO_2颗粒中的扩散长度更长。另外，估计10nm金NP在近红外波长（1200nm）处的两光子吸收截面大至10〜8GM（1GM = 10〜（-50）cm〜4sphoton〜（- 1）分子〜（-1））。

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