PUB - Publikationen an der Universität Bielefeld

The influence of chromium and antimony codoping on the surface structure of rutile TiO(2)(110) was studied at the atomic level using noncontact atomic force microscopy, Compared to pristine TiO(2)(110), the codoped surface exhibits substantial surface facetting. A careful analysis of high-resolution images unraveled a surface reconstruction that closely resembles a (I x 4) structure, indicating a firm integration of the dopant atoms into the titanium dioxide crystal. The reconstruction can be described by shearing the original unit cell by an angle of 7 +/- 1 degrees. We provide a simple explanation of the observed reconstruction by comparing both the ionic as well as the covalent radii of chromium and antimony with those of titanium. On the basis of this simple picture, the observed reconstruction can be understood as a strategy to compensate for the significantly smaller covalent radii of the dopant atoms. The observed surface facetting is explained by reconstruction-induced interlayer stress. This facetting might be beneficial for photocatalytic activity. Our results thus shed light on the role of chromium and antimony dopants in the wide band gap photocatalyst titania.