N doping of TiO 2(110) Photoemission and density-functional studies

A. Nambu, J. Graciani, J. A. Rodriguez, Q. Wu, E. Fujita, J. Fdez Sanz

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124 Citations (Scopus)

Abstract

The electronic properties of N-doped rutile TiO 2(110) have been investigated using synchrotron-based photoemission and density-functional calculations. The doping via N 2 + ion bombardment leads to the implantation of N atoms (∼5% saturation concentration) that coexist with O vacancies. Ti 2p core level spectra show the formation of Ti 3+ and a second partially reduced Ti species with oxidation states between +4 and +3. The valence region of the TiO 2-xN y(110) systems exhibits a broad peak for Ti 3+ near the Fermi level and N-induced features above the O 2p valence band that shift the edge up by ∼0.5 eV. The magnitude of this shift is consistent with the "redshift" observed in the ultraviolet spectrum of N-doped TiO 2. The experimental and theoretical results show the existence of attractive interactions between the dopant and O vacancies. First, the presence of N embedded in the surface layer reduces the formation energy of O vacancies. Second, the existence of O vacancies stabilizes the N impurities with respect to N 2(g) formation. When oxygen vacancies and N impurities are together there is an electron transfer from the higher energy 3d band of Ti 3+ to the lower energy 2p band of the N 2- impurities.

Original languageEnglish
Article number094706
JournalJournal of Chemical Physics
Volume125
Issue number9
DOIs
Publication statusPublished - Sep 18 2006

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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    Nambu, A., Graciani, J., Rodriguez, J. A., Wu, Q., Fujita, E., & Sanz, J. F. (2006). N doping of TiO 2(110) Photoemission and density-functional studies. Journal of Chemical Physics, 125(9), [094706]. https://doi.org/10.1063/1.2345062