Advertisement

Journal of Nanoparticle Research

, Volume 10, Issue 1, pp 77–85 | Cite as

Preparation of core-shell Ti-Nb oxide nanocrystals

  • David S. A. Simakov
  • Yoed Tsur
Article

Abstract

Nanosized powders of Ti-Nb oxide core-shell nanocrystals with atomic ratios of Nb/Ti = 0.11, 0.25, and 0.38 have been prepared by two preparation routes. The first route was co-precipitation, followed by␣annealing, using NbCl5 as a source of Nb. The second route was coating of pure TiO2 nanocrystals by Nb-isopropoxide in liquid medium, followed by impregnation of the Nb into the nanoparticles by annealing. Both methods yielded anatase nanocrystals with a Nb-rich shell and a core, which had much lower Nb loadings. The anatase structure solid solution (with Nb incorporated) was stable under annealing up to 760°C. The particle size remained within the nanometric scale (<50 nm) under heat-treatment up to 760°C. It has been shown that the fabricated powders can be redispersed in aqueous media by simple ultrasound treatment, resulting in nanosized dispersions. Using a variety of analytical techniques, including depth profiling of single nanocrystallites by AES combined with sputtering by Ar ions, the mechanism of the core-shell structure creation was studied. It is proposed that the formation of the core-shell structure is governed by solubility limitations in the co-precipitation route and by solubility and diffusion limitations in the coating-incorporation route.

Keywords

titania anatase niobium solid solutions core-shell nanocrystallite nanosized dispersion coating wet synthesis 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Anukunprasert T., Saiwan C., Traversa E. (2005) The development of gas sensor for carbon monoxide monitoring using nanostructure of Nb-TiO2. Sci. Technol. Adv. Mater. 6:359–363CrossRefGoogle Scholar
  2. Arbiol J., Cerdà J., Dezanneau G., Cirera A., Peirò F., Cornet A., Morante J.R. (2002) Effects of Nb doping on the TiO2 anatase-to-rutile phase transition. J. Appl. Phy. 92(2):853–861CrossRefGoogle Scholar
  3. Atashbar M.Z., Sun H.T., Gong B., Wlodarski W., Lamb R. (1998) XPS study of Nb-doped oxygen sensing TiO2 thin films prepared by sol-gel method. Thin Solid Films 326:238–244CrossRefGoogle Scholar
  4. Chappel S., Chen S.G., Zaban A. (2002) TiO2-coated nanopoprous SnO2 electrodes for dye-sensitized solar cells. Langmuir 18:3336–3342CrossRefGoogle Scholar
  5. Chen S.G., Chappel S., Diamant Y., Zaban A. (2001) Preparation of Nb2O5 coated TiO2 nanoporous electrodes and their application in dye-sensitized solar cells. Chem. Mater. 13:4629–4634CrossRefGoogle Scholar
  6. Cui H., Dwight K., Soled S., Wold A. (1995) Surface acidity and photocatalytic activity of Nb2O5/TiO2 photocatalysts. J. Solid State Chem. 115:187–191CrossRefGoogle Scholar
  7. Ferroni M., Carotta M.C., Guidi V., Martinelli G., Ronconi F., Richard O., Van Dyck D., Van Landuyt J. (2000) Structural characterization of Nb-TiO2 nanosized thick-films for gas sensing applications. Sens. Actuators B 68:140–145CrossRefGoogle Scholar
  8. Gao Y., Liang Y., Chambers S.A. (1996) Synthesis and characterization of Nb-doped TiO2 (110) surfaces by molecular beam epitaxy. Surf.Sci. 348:17–27CrossRefGoogle Scholar
  9. Grätzel M. (2001) Photoelectrochemical cells. Nature 414:338–344CrossRefGoogle Scholar
  10. Hagfeldt A., Grätzel M. (2000) Molecular photovoltaics. Acc. Chem. Res. 33(5):269–277CrossRefGoogle Scholar
  11. Hirano M., Matsushima K. (2006) Effect of niobium on the structure and photoactivity of anatase (TiO2) nanoparticles. J. Nanosci. Nanotechnol. 6(3):762–770Google Scholar
  12. Kay A., Grätzel M. (2002) Dye-sensitized core-shell nanocrystals: Improved efficiency of mesoporous tin oxide electrodes coated with a thin layer of an insulating oxide. Chem. Mater. 14:2930–2935CrossRefGoogle Scholar
  13. Morris D., Dou Y., Rebane J., Mitchell C.E.J., Egdell R.G. (2000) Photoemission and STM study of the electronic structure of Nb-doped TiO2. Phy. Rev. B 61(20):13445–13457CrossRefGoogle Scholar
  14. Palomares E., Clifford J.N., Haque S.A., Lutz T., Durrant J.R. (2003) Control of charge recombination dynamics in dye sensitized solar cells by the use of conformally deposited metal oxide blocking layers. J. Am. Chem. Soc. 125:475–482CrossRefGoogle Scholar
  15. Park N.G., Kang M.G., Kim K.M., Ryu K.S., Chang S.H. (2004) Morphological and photoelectrochemical characterization of core-shell nanoparticle films for dye-sensitized solar cells: ZnO type shell on SnO2 and TiO2 cores. Langmuir 20:4246–4253CrossRefGoogle Scholar
  16. Ruiz A., Calleja A., Espiell F., Cornet A., Morante J.R. (2003) Nanosized Nb-TiO2 gas sensors derived from alkoxides hydrolization. IEEE Sens. J. 3(2):189–194CrossRefGoogle Scholar
  17. Simakov S.A., Tsur Y. (2006) Surface stabilization of nano-sized titanium oxide: Improving the colloidal stability and the sintering morphology. J. Nanopart. Res., DOI  10.1007/s11051-006-9099-0
  18. Védrine J.C., Coudurier G., Ouqour A., Pries de Oliveira P.G., Volta J.C. (1996) Niobium oxide based materials as catalysts for acidic and partial oxidation type reactions. Catal. Today 28:3–15CrossRefGoogle Scholar
  19. Wang Z.S., Huang C.H., Huang Y.Y., Hou Y.J., Xie P.H., Zhang B.W., Cheng H.M. (2001) A highly efficient solar cell made from a dye-modified ZnO-covered TiO2 nanoporous electrode. Chem. Mater. 13:678–682CrossRefGoogle Scholar
  20. Whang C.M., Kim J.G., Hwang H.J. (2005) Photocatalytic properties of the transition metal doped TiO2 powder prepared by Sol-Gel process. Key Eng. Mater. 1:280–283Google Scholar
  21. Yamada Y., Seno Y., Masuoka Y., Nakamura T., Yamashita K. (2000) NO2 sensing characteristics of Nb-doped TiO2 thin films and their electronic properties. Sens. Actuators B 66:164–166CrossRefGoogle Scholar
  22. Yang S., Huang Y., Huang C., Zhao X. (2002) Enhanced energy conversion efficiency of the Sr2+-modified nanoporous TiO2 electrode sensitized with a ruthenium complex. Chem. Mater. 14:1500–1504CrossRefGoogle Scholar
  23. Young R.A. (1993) The Rietveld Method. Oxford University PressGoogle Scholar
  24. Zaban A., S.G. Chen, S. Chappel, B.A. Gregg, 2000. Bilayer nanoporous electrodes for dye sensitized solar cells. Chem. Commun. 2231–2232Google Scholar

Copyright information

© Springer Science+Business Media, Inc. 2007

Authors and Affiliations

  1. 1.Department of Chemical EngineeringTechnion-Israel Institute of TechnologyHaifaIsrael

Personalised recommendations