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

虽然锐钛矿型二氧化钛在空气和水中的氧化还原效率通常是最好的单相材料，但混合相二氧化钛(锐钛矿型+金红石型)通常表现出比单一相更高的光活性。然而，对这些现象缺乏详细的解释。格雷团队最近的工作揭示了混合相二氧化钛中电荷分离、陷阱和复合的本质。纳米结构由金红石和锐钛矿相互交织的微晶组成，形成了固-固界面，光激发电子通过该界面从金红石向低能锐钛矿晶格陷阱转移。物理气相沉积薄膜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、颗粒大小、缺陷)。取向和界面)与观察到的现象有关。通过开发适当的过程控制，受控合成和表征将与了解界面结构和功能的功能相关联，包括其在为增强光催化响应提供活性中心方面的作用。功能将根据对紫外线和可见光辐射暴露的二氧化碳减少来衡量。

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.