AVS 53rd International Symposium
    Surface Science Friday Sessions
       Session SS-FrM

Paper SS-FrM5
Nitrogen Doping of TiO@sub 2@ Single Crystals

Friday, November 17, 2006, 9:20 am, Room 2002

Session: Oxide Surfaces and Interfaces
Presenter: M. Batzill, Tulane University
Authors: M. Batzill, Tulane University
E.H. Morales, Tulane University
U. Diebold, Tulane University
Correspondent: Click to Email
TiO@sub 2@ is one of the most widely used photocatalytic materials for photo degradation of organic pollutants, self cleaning surfaces, and photolysis of water for hydrogen production. The wide band gap of TiO@sub 2@ limits its photoactivity to UV radiation, however. For utilizing a wider spectrum of the solar light a narrower band gap would be advantageous. In a recent paper by Asahi et al.@footnote 1@ it was proposed that such a band gap narrowing can be achieved by doping TiO@sub 2@ with nitrogen. Here we present detailed photoemission and scanning tunneling microscopy studies of single crystal rutile and anatase TiO@sub 2@ samples, which were nitrogen-doped by ion implantation.@footnote 2@ Only one oxynitride species was identified in XPS for nitrogen. Valence band spectra showed additional states at the top of the valence band for N-doped samples. These were identified as N-2p states, which appear to be not strongly hybridized with the O-2p valence band of pure TiO@sub 2@. Changes in Ti-3d induced defect states within the band gap are discussed in terms of N@super 3-@ induced charge compensation processes. We conclude that N-doping lowers the O-vacancy formation energy, which also triggers a 2x1 surface reconstruction of the rutile-TiO@sub 2@(110) surface upon N-doping. @FootnoteText@ @footnote 1@ R. Asahi, T. Morikawa, T. Ohwaki, K. Aoki, Y. Taga, Science 293, 269 (2001).@footnote 2@ M. Batzill, E.H. Morales, U. Diebold, Phys. Rev. Lett. 96, 026103 (2006).