US EPA

1583113 

Journal Article 

Creating Oxygen Vacancies as a Novel Strategy To Form Tetrahedrally Coordinated Ti4+ in Fe/TiO2 Nanoparticles 

Wu, Q; Zheng, Q; van De Krol, R 

2012 

Yes 

Journal of Physical Chemistry C
ISSN: 1932-7447
EISSN: 1932-7455 

116 

12 

7219-7226 

10.1021/jp212577g 

WOS:000302051100055 

The incorporation of Fe as a dopant in anatase TiO2
nanoparticles has been systematically investigated with the aim of changing the coordination
geometry of Ti via the formation of oxygen vacancies. Although Fe3+ ions are present in the
solution during growth of the nanoparticles, a high-temperature heat treatment is found to be
necessary to incorporate Fe3+ as a substituent for Ti4+ in the bulk of the TiO2 nanoparticles.
The Fe3+ acceptors are found to be charge-compensated by oxygen vacancies, up to dopant
concentrations as high as 10%. The surprisingly high solubility of Fe is attributed to the very
similar radii of Ti4+ and Fe3+ and to the energetically favorable Coulomb attraction between the
negatively charged Fe acceptor and the positively charged oxygen vacancies. A combined
EXAFS/XANES study reveals that part of the Ti4+ ions changes their coordination number from 6 to
4 at high oxygen vacancy concentrations. The deliberate use of oxygen vacancies to modify the
coordination geometry of metal ions represents a new strategy that offers exciting possibilities
to tune the selectivity of photocatalytically active metal oxide nanoparticles.