Second Generation Photocatalysts: TiO2-Based Nanocomposites by dc Reactive Sputtering

虽然TiO 2的金红石相在空气和水中的氧化还原效率方面通常是最好的单相材料，但混合相TiO 2（金红石+金红石）通常表现出比单独的纯相更高的光活性。然而，这些现象的详细解释是缺乏的。格雷小组最近的工作揭示了混合相二氧化钛中电荷分离、捕获和复合的本质。存在由金红石和金红石的交织微晶组成的纳米结构形态，其产生固-固界面，光激发的电子穿过该固-固界面从金红石转移到较低能量的金红石晶格捕获位点。 薄膜的物理气相沉积提供了一种直接的方法来系统地探索固体的结构方面（相组成，晶粒尺寸，缺陷）。方向和界面）与观察到的现象的关系。通过开发适当的工艺控制，受控合成和表征将与功能相关，以了解界面结构和功能，包括其在提供活性位点以增强光催化反应中的作用。 功能性将根据对紫外线和可见光辐射暴露的响应中CO2的减少来测量。

While the anatase phase of TiO2 is generally the best single-phase material in terms of its redox efficiency in air and water, mixed phase TiO2 (anatase + rutile) often exhibits higher photoactivity than pure phases alone. A detailed explanation of these phenomena, however, is lacking. Recent work in Gray's group has revealed insights into the nature of charge separation, trapping and recombination in mixed phase titania. There is a nanostructured morphology comprised of interwoven crystallites of rutile and anatase creating solid-solid interfaces across which photoexcited electrons are transferred from rutile to lower energy anatase lattice trapping sites. Physical vapor deposition of thin films offers a direct approach to systematically explore the structural aspects of solids (phase composition, grain size, defects. orientation and interfaces) in relation to the observed phenomena. By developing appropriate process controls, controlled synthesis and characterization will be correlated with functionality to understand interfacial structure and function, including its role in providing active sites for enhanced photocatalytic response. Functionality will be measured in terms of the reduction of CO2 in response to UV and visible radiation exposure.