Nitrogen doping-induced changes in the electronic properties, defect formation, and surface structure of TiO2 rutile(110) and anatase(101) single crystals were investigated. No band gap narrowing is observed, but N doping induces localized N 2p states within the band gap just above the valence band. N is present in a N(III) valence state, which facilitates the formation of oxygen vacancies and Ti 3d band gap states at elevated temperatures. The increased O vacancy formation triggers the 1×2 reconstruction of the rutile (110) surface. This thermal instability may degrade the catalyst during applications.
Reprints available from U. Diebold (diebold).
Users with online access to Physical Review Letters can load the article from the publisher.