| AVS 58th Annual International Symposium and Exhibition | |
| Thin Film Division | Tuesday Sessions |
| Session TF+SE-TuM |
| Session: | Glancing Angle Deposition (GLAD) I |
| Presenter: | George Larsen, University of Georgia |
| Authors: | G.K. Larsen, University of Georgia R. Fitzmorris, University of California Santa Cruz J.Z. Zhang, University of California Santa Cruz Y.P. Zhao, University of Georgia |
| Correspondent: | Click to Email |
In order to achieve efficient photocatalytic behavior in the visible light range, transition metal ions are often doped into TiO2. Of these transition metal dopants, Cr appears superior in extending the photoresponse of TiO2 into the visible range. However, different fabrication methods have produced mixed results regarding the effect of the Cr dopant on photocatalytic efficiency. In this study, a unique fabrication method, oblique angle co-deposition (OACD), is used to deposit a well-aligned array of Cr-doped TiO2 nanorods that exhibit optical absorption in the visible region. These films are compared with TiO2 nanorod arrays fabricated by oblique angle deposition (OAD). Due to the similarity of fabrication methods, the effect of the dopant on the structural, optical, and photocatalytic properties of TiO2 can be isolated. The Cr dopant alters the TiO2 lattice structure, with an increase in the crystallization temperature of the anatase phase and a decrease in the rutile crystallization temperature. Additionally, Cr is found to segregate out of the TiO2 matrix and migrate to grain boundaries and the surface of the nanorods. The photocatalytic efficiency and IPCE of the Cr:TiO2 films is reduced when compared to intrinsic TiO2 due to changes in the photocatalyst’s surface and charge transport properties as a result of the formation of intergranular Cr(VI) oxide clusters. The presence and the effects of the Cr(VI) phase is the result of exceeding the solubility limits of Cr within the TiO2 lattice.