Nanotechnology on Surfaces Laboratory, Materials Science Institute of Seville, CSIC-University of Seville, Avd. Américo Vespucio 49, 41092 Spain.
Chemphyschem. 2011 Jan 17;12(1):191-6. doi: 10.1002/cphc.201000734. Epub 2010 Dec 14.
Herein, we study the photoactivity of anatase-rutile bilayer thin films consisting of an anatase overlayer of variable thickness from some tenths to some hundred nanometers deposited onto a rutile thin film. As references single anatase layers of equivalent thickness were deposited onto silicon. All the films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectroscopy. The photoactivity of the samples was assessed by following the evolution with the UV illumination time of both the wetting angle on the thin film surface and the decoloration of a dye in a water solution. While a similar efficiency is found for the first type of experiments irrespective of the anatase thickness, in the second type a maximum in the photoactivity is found for a thickness of the anatase layer of about 130 nm. This enhanced photoactivity in bilayer systems with a buried anatase-rutile heterojunction is related to the formation of different Schottky potential barriers in the anatase layer, depending on its thickness and the substrate (i.e. rutile or SiO(2)) where it is deposited.
在此，我们研究了由锐钛矿覆盖层和金红石薄膜组成的锐钛矿-金红石双层薄膜的光活性，锐钛矿覆盖层的厚度从几十纳米到几百纳米不等。作为参考，我们在硅衬底上沉积了相同厚度的单层锐钛矿。所有薄膜均通过 X 射线衍射（XRD）、扫描电子显微镜（SEM）和拉曼光谱进行了表征。通过观察薄膜表面润湿性随紫外光照射时间的变化以及水溶液中染料的褪色情况，评估了样品的光活性。尽管对于第一种类型的实验，无论锐钛矿的厚度如何，效率都相似，但在第二种类型的实验中，发现当锐钛矿层的厚度约为 130nm 时，光活性达到最大值。这种在具有埋层锐钛矿-金红石异质结的双层体系中增强的光活性与锐钛矿层中形成的不同肖特基势垒有关，这取决于其厚度以及沉积其上的衬底（即金红石或 SiO2）。
