Photoinduced charge-transfer processes on MOF-5 nanoparticles: Elucidating differences between metal-organic frameworks and semiconductor metal oxides
Photoinduced charge-transfer processes on MOF-5 nanoparticles: Elucidating differences between metal-organic frameworks and semiconductor metal oxides
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DOI：
10.1021/jp803620v
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发表时间：
2008-09-11
影响因子：
3.7
通讯作者：
Majima, Tetsuro
中科院分区：
文献类型：
--
作者：
Tachikawa, Takashi;Choi, Jun Rye;Majima, Tetsuro
金属有机框架（MOF）在溶剂去除后表现出大表面积和孔隙率保留，由于其优雅的拓扑结构以及在分离、血管存储、非线性光学和催化方面的潜在应用而引起了广泛的关注。我们在此报告了 MOF-5 纳米颗粒（称为 MOF-5_n）中发光跃迁性质的综合研究，以及从光激发 MOF-5_n 到各种有机化合物的界面碳转移。结合时间分辨漫反射（TDR）和荧光光谱，以阐明 MOF-5_n 上有机化合物的光诱导单电子氧化过程。阐明了 MOF-5 中的发光跃迁的温度依赖性，并与 ZnO 纳米颗粒的光谱特性进行了比较，然后使用稳态和时间分辨荧光光谱法直接研究了 MOF-5_n 在乙腈中的 355 nm 激光闪光光解过程中 S 的单电子氧化反应。 TDR 光谱显示，MOF-5 比最常见的光催化剂 P-25 TiO2 粉末具有更高的氧化反应效率。实验数据根据电子转移反应的 Marcus 理论进行了合理化。此外，由于 MOF 晶体形态在合成过程中或抽真空后会受到水的影响，因此本研究提供了了解光致电荷转移过程差异的绝佳机会。 MOF 和半导体之间。
Metal-organic frameworks (MOFs), which exhibit large surface area and porosity retention upon solvent removal, have attracted considerable attention due to their elegant topology and potential applications in separation, vas storage, nonlinear optics, and catalysis. We report herein comprehensive studies on the nature Of luminescence transitions in MOF-5 nanoparticles, which are referred to as MOF-5_n, and the interfacial char(,e transfer from the photoexcited MOF-5_n to various organic compounds. The time-resolved diffuse reflectance (TDR) and fluorescence spectroscopies were combined in order to clarify the photoinduced one-electron oxidation processes of organic compounds on the MOF-5_n. First, to identify the nature of the luminescence transitions in MOF-5, the temperature dependences of the spectral characteristics were elucidated and compared with those of ZnO nanoparticles. The quenching of MOF-5 emission by several substrates (S), Such as aromatic Sulfides and amines, was then investigated using steady-state and time-resolved fluorescence spectroscopies. The one-electron oxidation reaction of S during the 355 nm laser flash photolysis of MOF-5_n in acetonitrile was directly examined using TDR spectroscopy, and it was revealed that MOF-5 has a Much higher oxidation reaction efficiency than that of P-25 TiO2 powder, which is the most common photocatalyst. The experimental data were rationalized in terms of the Marcus theory on the electron transfer reactions. Moreover, the influence of adsorbed water on the reaction processes was examined because the MOF crystal morphology is affected by exposure to water during synthesis or after evacuation. Consequently, the present Study provides an excellent opportunity to understand the difference in the photoinduced charge-transfer processes between MOFs and semiconductors.