Evaluation of electron-hole recombination properties of titanium (IV) oxide particles with high photocatalytic activity
Evaluation of electron-hole recombination properties of titanium (IV) oxide particles with high photocatalytic activity
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DOI：
10.1163/156856707779238612
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发表时间：
2007-03
影响因子：
3.3
通讯作者：
Shin-ya Murakami;H. Kominami;Y. Kera;S. Ikeda;H. Noguchi;K. Uosaki;B. Ohtani
中科院分区：
文献类型：
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作者：
Shin-ya Murakami;H. Kominami;Y. Kera;S. Ikeda;H. Noguchi;K. Uosaki;B. Ohtani
电子空穴复合在纳米尺寸的氧化钛（IV）（TiO 2）颗粒具有各种物理特性，已被证明是高活性的光催化剂，通过定量分析的还原钛物种（Ti 3+），这可能是通过光照射在脱气条件下的空穴清除剂的存在下，在TiO 2颗粒的晶体缺陷位点形成的评价。这些高活性的光催化剂样品是通过在有机介质中水热晶化（HyCOM方法）和后煅烧合成的。Ti 3+密度随煅烧温度（Tc）的升高而降低，并且通过飞秒泵浦-探测漫反射光谱（Pump-probe diffuse reflection spectroscopy）研究发现，Ti 3+密度与电子-空穴复合速率常数呈线性相关。对于光催化银金属沉积沿着氧形成，在脱气条件下从Ag+水溶液测量反应速率（RAg）和吸附在TiO 2颗粒上的银离子（Ag+）的量（[Ag+]ads），并确定RAg相对于[Ag+]ads图的斜率。该反应的动力学研究表明，斜率的倒数近似与电子-空穴复合速率和电子俘获速率之比（kr/ke比）有关。kr/ke比值随Tc的增加而减小，kr/ke比值的对数与Ti ~（3+）浓度呈线性关系。这两个参数被用来作为一个措施的复合性能的TiO 2光催化剂具有各种物理性能。
Electron-hole recombination in nano-sized titanium(IV) oxide (TiO2) particles with various physical properties, which have been shown to be highly active photocatalysts, was evaluated by quantitative analysis of reduced titanium species (Ti3+), which might be formed at crystalline defective sites in TiO2 particles through photo-irradiation in the presence of a hole scavenger under deaerated conditions. These highly active photocatalyst samples were synthesized by hydrothermal crystallization in organic media (HyCOM method) and post-calcination. The Ti3+ density decreased with increasing calcination temperature (Tc), and a linear correlation was observed between the Ti3+ density and rate constant for electron-hole recombination evaluated by femtosecond pump-probe diffuse reflection spectroscopy. Reaction rate (RAg) and the amount of silver ions (Ag+) adsorbed on TiO2 particles ([Ag+]ads) were measured for photocatalytic silver metal deposition along with oxygen formation from an aqueous Ag+ solution under deaerated conditions, and the slope of the RAgversus [Ag+]ads plot was determined. Kinetic investigation of this reaction showed that the reciprocal of the slope was approximately related to the ratio of the rates for electron-hole recombination and electron trapping (kr/ke ratio). The kr/ke ratio decreased as Tc increased, and the logarithm of the kr/ke ratio was linearly related with Ti3+ density. These two parameters were used as a measure for the recombination properties of TiO2 photocatalysts with various physical properties.