Enhancement in the photocatalytic nature of nitrogen-doped PVD-grown titanium dioxide thin films

Journal Article · Tue Dec 01 00:00:00 EST 2009 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3269702· OSTI ID:21359376

Tavares, C J; Marques, S M; Viseu, T; Teixeira, V; Carneiro, J O ^[1]; Alves, E; Barradas, N P ^[2]; Munnik, F ^[3]; Girardeau, T; Riviere, J -P ^[4]

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1. Centre of Physics-GRF, University of Minho, 4800-058 Guimaraes (Portugal)
2. Ion Beam Laboratory (ITN), EN 10, 2686-953 Sacavem (Portugal)
3. Forschungszentrum Dresden Rossendorf, D-01314 Dresden (Germany)
4. PhyMat, University of Poitiers, 86962 Futuroscope-Chasseneuil (France)

Nitrogen-doped titanium dioxide semiconductor photocatalytic thin films have been deposited by unbalanced reactive magnetron physical vapor deposition on glass substrates for self-cleaning applications. In order to increase the photocatalytic efficiency of the titania coatings, it is important to enhance the catalysts absorption of light from the solar spectra. Bearing this fact in mind, a reduction in the titania semiconductor band-gap has been attempted by using nitrogen doping from a coreactive gas mixture of N{sub 2}:O{sub 2} during the titanium sputtering process. Rutherford backscattering spectroscopy was used in order to assess the composition of the titania thin films, whereas heavy-ion elastic recoil detection analysis granted the evaluation of the doping level of nitrogen. X-ray photoelectron spectroscopy provided valuable information about the cation-anion binding within the semiconductor lattice. The as-deposited thin films were mostly amorphous, however, after a thermal annealing in vacuum at 500 deg. C the crystalline polymorph anatase and rutile phases have been developed, yielding an enhancement in the crystallinity. Spectroscopic ellipsometry experiments enabled the determination the refractive index of the thin films as a function of the wavelength, while from the optical transmittance it was possible to estimate the semiconductor indirect band-gap of these coatings, which has been proven to decrease as the N-doping increases. The photocatalytic performance of the titania films has been characterized by the degradation rate of an organic reactive dye under UV/visible irradiation. It has been found that for a certain critical limit of 1.19 at. % of nitrogen doping in the titania anatase crystalline lattice enhances the photocatalytic behavior of the thin films and it is in accordance with the observed semiconductor band-gap narrowing to 3.18 eV. By doping the titania lattice with nitrogen, the photocatalytic activity is enhanced under both UV and visible light.

• OSTI ID: 21359376
• Journal Information: Journal of Applied Physics, Vol. 106, Issue 11; Other Information: DOI: 10.1063/1.3269702; (c) 2009 American Institute of Physics; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANIONS
ANNEALING
CATIONS
COATINGS
DOPED MATERIALS
ELLIPSOMETRY
HEAVY IONS
NITROGEN
PHOTOCATALYSIS
PHOTOCHEMISTRY
PHYSICAL VAPOR DEPOSITION
REFRACTIVE INDEX
RUTHERFORD BACKSCATTERING SPECTROSCOPY
RUTILE
SEMICONDUCTOR MATERIALS
SPUTTERING
THIN FILMS
TITANIUM
TITANIUM OXIDES
X-RAY PHOTOELECTRON SPECTROSCOPY
CATALYSIS
CHALCOGENIDES
CHARGED PARTICLES
CHEMISTRY
DEPOSITION
ELECTRON SPECTROSCOPY
ELEMENTS
FILMS
HEAT TREATMENTS
IONS
MATERIALS
MEASURING METHODS
METALS
MINERALS
NONMETALS
OPTICAL PROPERTIES
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
PHYSICAL PROPERTIES
RADIOACTIVE MATERIALS
RADIOACTIVE MINERALS
SPECTROSCOPY
SURFACE COATING
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS