Acta Phys. -Chim. Sin. ›› 2013, Vol. 29 ›› Issue (07): 1363-1369.doi: 10.3866/PKU.WHXB201305221

• COMMUNICATION • Previous Articles     Next Articles

Preparation, Characterization and Photocatalytic Activity of Cr-Doped Rutile TiO2(110) Single Crystal Thin Films

WANG Yang1, SHAO Xiang2, WANG Bing1   

  1. 1 Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, P. R. China;
    2 Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, P. R. China
  • Received:2013-04-02 Revised:2013-05-22 Published:2013-06-14
  • Contact: WANG Bing E-mail:bwang@ustc.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (90921013).

Abstract:

The growth of Cr-doped rutile TiO2(110) homoepitaxial single crystal thin films was investigated using pulsed laser deposition (PLD) method. Surface morphology and electronic structure were characterized using scanning tunneling microscopy/spectroscopy (STM/STS), X-ray and ultraviolet photoemission spectroscopy (XPS/UPS). The optical absorption spectra were measured using ultravioletvisible (UV-Vis) absorption spectroscopy. From STM images, we observed that the atomic flat TiO2(110)-(1×1) surface maintained at Cr doping concentration of 6% (atomic ratio), indicating a negligible effect of the Cr dopants on the surface morphology. The Cr doped ruteile TiO2(110) film showed higher tunneling conductance than undoped rutile single crystal. XPS and UPS spectra indicated that Cr atoms bond to lattice O, exhibiting an +3 oxidation state of +3 and introducing an impurity state above the valence band maximum by 0.4 eV. The UV-Vis absorption spectrum of the Cr doped film showed an absorbance extended to ~650 nm, in a visible light range, which was consistent with the UPS spectra. Using the Cr-doped TiO2 films, the dissociation of methanol molecules was only observed under the UV light illumination (wavelength shorter than 430 nm), however, the dissociation reaction was not observed under the visible light illumination (wavelength longer than 430 nm). Our results suggest that the monodoping by Cr element may not be sufficient to promote the visible light photoactivity of rultile TiO2(110) surface.

Key words: Rutile TiO2 thin film, Cr-doped, Band structure, Photocatalysis

MSC2000: 

  • O644