Single-molecule, single-particle observation of size-dependent photocatalytic activity in Au/TiO2 nanocomposites
Single-molecule, single-particle observation of size-dependent photocatalytic activity in Au/TiO2 nanocomposites
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DOI：
10.1039/c0sc00648c
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发表时间：
2011-05
期刊：
影响因子：
8.4
通讯作者：
Nan Wang;T. Tachikawa;T. Majima
中科院分区：
文献类型：
--
作者：
Nan Wang;T. Tachikawa;T. Majima
纳米复合材料的结构单元之间的电子通信是影响其在许多光电和催化应用方面的功能的重要性质。在这里，我们报告了一个单分子，单颗粒的方法来阐明固有的光催化活性的个别Au纳米粒子负载的二氧化钛颗粒使用一种新的氧化还原响应荧光染料。从产品发出的荧光猝发的单粒子动力学分析表明，光催化活性导致探针分子的减少不仅由基板浓度和激发强度，但也Au颗粒大小控制，这些因素是错综复杂的相互关联。此外，我们发现，周围的毫秒到秒的时间尺度的随机光催化事件在光照射过程中表现出相当大的时间和空间的异质性，他们实际上起源于充电/放电的Au纳米粒子的TiO 2。我们的研究结果代表了一个显着的贡献，在复合系统中的界面电子转移动力学的科学理解，更根本的是，在异质（光）化学过程。
Electronic communication between the building blocks of nanocomposites is an important property that affects their functionality with regard to many optoelectronic and catalytic applications. Herein, we report a single-molecule, single-particle approach for elucidating the inherent photocatalytic activity of individual Au nanoparticle-loaded TiO2 particles using a novel redox-responsive fluorescent dye. A single-particle kinetic analysis of the fluorescence bursts emitted from the products revealed that the photocatalytic activity leading to reduction of the probe molecules is controlled by not only the substrate concentration and excitation intensity but also the Au particle size, and that these factors are intricately interrelated. Furthermore, we discovered that the stochastic photocatalytic events around the millisecond-to-second time scale showed considerable temporal and spatial heterogeneity during photoirradiation, and that they actually originate from the charging/discharging of Au nanoparticles on TiO2. Our findings represent a significant contribution to the scientific understanding of the interfacial electron transfer dynamics in composite systems, and more fundamentally, in heterogeneous (photo)chemical processes.