Abstract
The authors investigate the formation of ultrathin oxides on rutile TiO2(011) single crystal surfaces by scanning tunneling microscopy and photoemission techniques in view of the role of substrate orientation for the formation of special oxide species and films. The authors observe that the (011) orientation of rutile facilitates the stabilization of ordered atomic-scale Cu+ species under weak oxidizing conditions. In contrast, clustering is observed on the (110) surface prepared under the same conditions. For chromium deposition in an oxidizing environment growth of an epitaxial but twinned Cr2O3 film with (1-102) orientation is observed. High crystalline order is maintained to the ultrathin monolayer limit. X-ray photoelectron spectroscopy suggests some diffusion of Ti3+ species into Cr2O3 films while the surface of Cr2O3 appears to be reducible by vacuum annealing to ∼300 °C. An increased photocatalytic activity for decomposition of methyl orange solution is measured for TiO2(011) surfaces modified with a submonolayer film of chromia while for thicker Cr2O3 films the photocatalytic activity decreases again.
Accepted Version
Published Version
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