Controlled Doping of TiO2 for Visible Light Photoactivity
EMSL Project ID
35220
Abstract
The ambition of supplementing the nation's energy needs through solar photocatalytic water splitting is a far from being realized with current photocatalytic materials. TiO2-based materials (anatase, rutile and various titanates) are promising photocatalysts that show activity in the UV and stability over a wide range of conditions. However, one of the problems with TiO2 as a stand-alone photocatalyst is that it absorbs little of the solar spectrum. Doping offers the possibility of incorporating donor and/or acceptor states into the TiO2 band gap that lower the threshold energy for photon absorption without significantly compromising photoactivity. While much applied work exists involving doping of TiO2, there has been little effort aimed at understanding the fundamental properties of doped TiO2. In this subtask, we examine the controlled doping of single crystal films of anatase and rutile TiO2 with both anion and cation dopants using oxygen plasma-assisted molecular beam epitaxy (OPAMBE). In previous work we explored the properties of N-doped rutile TiO2(110) and anatase TiO2(001). We show that the absorption thresholds of these are shifted into the visible, that a transition exists in dopant concentration between pure substitutional anion doping (N for O) and phase separation (new Ti oxynitride phase), and that the former shows signs of trapping holes during photon irradiation. In this new funding cycle, we will extend these studies to experimental and theoretical work on doping with C and Fe, both of which are known in the applied literature to promote visible light photocatalysis on TiO2.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2009-10-01
End Date
2011-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Du Y, NG Petrik, NA Deskins, Z Wang, MA Henderson, GA Kimmel, and I Lyubinetsky. 2012. "Hydrogen Reactivity on Highly-hydroxylated TiO2(110) Surfaces Prepared via Carboxylic Acid Adsorption and Photolysis." Physical Chemistry Chemical Physics. PCCP 14(9):3066-3074. doi:10.1039/C1CP22515D
"Epitaxial Growth and Orientational Dependence of Surface Photochemistry in Crystalline TiO2 Rutile Films Doped with Nitrogen." Journal of Physical Chemistry C 114(14): 6595-6601. Ohsawa, T., I. Lyubinetsky, Y. Du, M. A. Henderson, V. Shutthanandan and S. A. Chambers (2009)