In this article we investigate the structural and photocatalytic properties of W-doped titanium dioxide coatings. TiO 2-W thin films were deposited onto glass slides by reactive magnetron co-sputtering. The properties of the films were analyzed using such techniques as XRD, Raman spectroscopy, EDX, TEM, and surface profilometry. The photocatalytic properties of the coatings were assessed using the methylene blue (MB) degradation test under UV and fluorescent light sources. The methylene blue decomposition experiments showed that, at the optimum dopant concentration of tungsten, the photocatalytic activity can be improved by a factor of 6, compared to undoped titania. For the coatings discussed within this work, the optimum dopant concentration was determined to be 5.89 at.% of W. The results indicated that tungsten doping at this level extends the lifetime of the photogenerated charge carriers and significantly increases the photocatalyst surface area.
References
[1]
Rauf, M.A.; Meetani, M.A.; Hisaindee, S. An overview on the photocatalytic degradation of azo dyes in the presence of TiO2 doped with selective transition metals. Desalination 2011, 276, 13–27, doi:10.1016/j.desal.2011.03.071.
[2]
Ratova, M.; Kelly, P.J.; West, G.T.; Iordanova, I. Enhanced properties of magnetron sputtered photocatalytic coatings via transition metal doping. Surf. Coat. Technol. 2013, 228, S544–S549, doi:10.1016/j.surfcoat.2012.04.037.
[3]
Farahani, N.; Kelly, P.J.; West, G.; Ratova, M.; Hill, C.; Vishnyakov, V. Photocatalytic activity of reactively sputtered and directly sputtered titania coatings. Thin Solid Films 2011, 520, 1464–1469, doi:10.1016/j.tsf.2011.09.059.
[4]
Yao, M.; Chen, J.; Zhao, C.; Chen, Y. Photocatalytic activities of ion doped TiO2 thin films when prepared on different substrates. Thin Solid Films 2009, 517, 5994–5999, doi:10.1016/j.tsf.2009.03.169.
[5]
Lorret, O.; Francová, D.; Waldner, G.; Stelzer, N. W-doped titania nanoparticles for UV and visible-light photocatalytic reactions. Appl. Cat. B Environ. 2009, 91, 39–46, doi:10.1016/j.apcatb.2009.05.005.
[6]
Kelly, P.J.; Beevers, C.F.; Henderson, P.S.; Arnell, R.D.; Bradley, J.W.; B？cker, H. A comparison of the properties of titanium-based films produced by pulsed and continuous DC magnetron sputtering. Surf. Coat. Technol. 2003, 174–175, 795–800, doi:10.1016/S0257-8972(03)00356-6.
[7]
Kubacka, A.; Colón, G.; Fernández-García, M. Cationic (V, Mo, Nb, W) doping of TiO2-anatase: A real alternative for visible light-driven photocatalysts. Cat. Today 2009, 143, 286–292, doi:10.1016/j.cattod.2008.09.028.
[8]
Abdullah, M.A.; Chong, F.K. Dual-effects of adsorption and photodegradation of methylene blue by tungsten-loaded titanium dioxide. Chem. Eng. J. 2010, 158, 418–425, doi:10.1016/j.cej.2010.01.010.
[9]
Rampaul, A.; Parkin, I.P.; O’Neill, S.A.; DeSouza, J.; Mills, A.; Elliott, N. Titania and tungsten doped titania thin films on glass; active photocatalysts. Polyhedron 2003, 22, 35–44, doi:10.1016/S0277-5387(02)01333-5.
[10]
Li, X.Z.; Li, F.B.; Yang, C.L.; Ge, W.K. Photocatalytic activity of WOx-TiO2 under visible light irradiation. J. Photochem. Photobiol. A Chem. 2001, 141, 209–217, doi:10.1016/S1010-6030(01)00446-4.
[11]
ISO10678, Fine Ceramics, Advanced Technical Ceramics—Determination of Photocatalytic Activity of Surfaces in an Aqueous Medium by Degradation of Methylene Blue; ISO: Geneva, Switzerland, 2010.
[12]
Stengl, V.; Bakardjieva, S.; Murafa, N. Preparation and photocatalytic activity of rare earth doped TiO2 nanoparticles. Mat. Chem. Phys. 2009, 114, 217–226, doi:10.1016/j.matchemphys.2008.09.025.
[13]
Abdullah, M.A.; Chong, F.K. Preparation and characterization of tungsten-loaded titanium dioxide photocatalyst for enhanced dye degradation. J. Hazard. Mat. 2010, 176, 451–458, doi:10.1016/j.jhazmat.2009.11.050.
[14]
Fuerte, A.; Hernandez-Alonso, M.D.; Maira, A.J.; Martinez-Arias, A.; Fernandez-Garcia, M.; Conesa, J.C.; Soria, J. Visible light-activated nanosized doped-TiO2 photocatalysts. Chem. Commun. 2001, 2718–2719.
[15]
Tauc, J.; Grigorovici, R.; Vancu, A. Optical properties and electronic structure of amorphous germanium. Phys. Stat. Solid. B 1966, 15, 627–637, doi:10.1002/pssb.19660150224.
[16]
Kiriakidou, F.; Kondarides, D.I.; Verykios, X.E. The effect of operational parameters and TiO2-doping on the photocatalytic degradation of azo-dyes. Cat. Today 1999, 54, 119–130, doi:10.1016/S0920-5861(99)00174-1.
[17]
Imai, M.; Kikuchi, M.; Oka, N.; Shigesato, Y. Visible light-induced photocatalytic properties of WO3 films deposited by DC reactive magnetron sputtering. J. Vac. Sci. Technol. A Vac. Surf. Films 2012, 30, 031503, doi:10.1116/1.3696876.
[18]
Hathway, T.; Rockafellow, E.M.; Oh, Y.-C.; Jenks, W.S. Photocatalytic degradation using tungsten-modified TiO2 and visible light: Kinetic and mechanistic effects using multiple catalyst doping strategies. J. Photochem. Photobiol. A Chem. 2009, 207, 197–203, doi:10.1016/j.jphotochem.2009.07.010.
[19]
Biswas, S.; Hossain, M.F.; Shahjahan, M.; Takahashi, K.; Takahashi, T.; Fujishima, A. Investigation of photocatalytic activity of TiO2/WO3 bilayered thin films with various amounts of WO3 exposed surface. Am. Vac. Soc. 2009, 27, 880–884.
