Real-time single-molecule imaging of the spatial and temporal distribution of reactive oxygen species with fluorescent probes:: Applications to TiO2 photocatalysts
Real-time single-molecule imaging of the spatial and temporal distribution of reactive oxygen species with fluorescent probes:: Applications to TiO2 photocatalysts
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DOI：
10.1021/jp076335l
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发表时间：
2008-01-31
影响因子：
3.7
通讯作者：
Majima, Tetsuro
中科院分区：
文献类型：
--
作者：
Naito, Kazuya;Tachikawa, Takashi;Majima, Tetsuro
利用单分子荧光光谱法成功地实现了对光辐照后的TiO 2表面扩散的单重态氧（O-1（2））和羟基自由基（（OH）-O-中心点）等气载活性氧（ROS）的单分子检测。用甲苯二酰亚胺（TDI）和3 ′-对羟基苯基荧光素（HPF）作为荧光探针，分别对空气中的单O-1（2）和（OH）-O-中心点分子进行了选择性检测。在不同的条件下，如激发波长（UV或可见光）和TiO 2的类型（纯或氮（N）掺杂），从TiO 2表面的气载O-1（2）和（OH）-O-中心点的产生进行了研究。在紫外光激发下，从纯的和N掺杂的TiO 2样品中检测到O-1（2）和（OH）-O-中心点，而在可见光激发下仅从N掺杂的TiO 2中检测到O-1（2）。此外，空气中的（OH）-O-中心点分子的空间和时间分布的光照射的TiO 2表面扩散的实时单分子成像技术进行了研究。（OH）-O-中心点与HPF间的双分子反应速率常数可视为气载（OH）-O-中心点分子的稳态浓度，符合准一级反应动力学。此外，（OH）-O-中心点分子通过空气-水界面（在玻璃表面上，约50 μ m每1秒）的异常扩散直接观察和解释的超扩散模型。我们在这项单分子研究中的发现为气载ROS在固-气界面（包括TiO 2光催化剂、空气和氧化基质）的产生、扩散和反应过程提供了新的见解。
The single-molecule detection of airborne reactive ox gen species (ROS), such as singlet oxygen (O-1(2)) and hydroxyl radical ((OH)-O-center dot), diffused from the photoirradiated TiO2 surface, was successfully demonstrated using single-molecule fluorescence spectroscopy. Airborne single O-1(2), and (OH)-O-center dot molecules were selectively detected by the fluorescent probes, terrylenediimide (TDI) and 3'-(p-hydroxyphenyl) fluorescein (HPF), respectively. Generation of ' the airborne O-1(2), and (OH)-O-center dot from the TiO2 surface has been investigated under various conditions, such as the excitation wavelengths (UV or visible) and the types of TiO2 (pure or nitrogen (N)-doped). Upon UV excitation, O-1(2) and (OH)-O-center dot were detected from both the pure and N-doped TiO, samples, while O-1(2) was exclusively detected only from the N-doped TiO2 upon visible excitation. Furthermore, the spatial and temporal distribution of the airborne (OH)-O-center dot molecules diffused from the photoirradiated TiO2 surface was investigated by the real-time single-molecule imaging technique. The bimolecular reaction rate constant between (OH)-O-center dot and HPF, which obeys pseudo first-order kinetics, can be regarded as a steady-state concentration of the airborne (OH)-O-center dot molecules. Additionally, the anomalous diffusion of (OH)-O-center dot molecules through an air-water interface (on glass surface, roughly 50 mu m per 1 s) was directly observed and interpreted in terms of the superdiffusive model. Our finding in this single-molecule study provides new insights into the generation, diffusion, and reaction processes of the airborne ROS at the solid-air interfaces including TiO2 photocatalysts, air, and oxidizing substrates.