Influence of substrate on structural properties and photocatalytic activity of TiO 2 films
2016; Institution of Engineering and Technology; Volume: 12; Issue: 2 Linguagem: Inglês
10.1049/mnl.2016.0550
ISSN1750-0443
AutoresDong Pan, Haibo Fan, Zan Li, Siyi Wang, Yinhao Huang, Yang Jiao, Yao He-bao,
Tópico(s)Gas Sensing Nanomaterials and Sensors
ResumoMicro & Nano LettersVolume 12, Issue 2 p. 82-86 ArticleFree Access Influence of substrate on structural properties and photocatalytic activity of TiO2 films Dong Pan, Dong Pan School of Physics, Northwest University, Xi'an, 710069 People's Republic of ChinaSearch for more papers by this authorHaibo Fan, Corresponding Author Haibo Fan hbfan@nwu.edu.cn School of Physics, Northwest University, Xi'an, 710069 People's Republic of ChinaSearch for more papers by this authorZan Li, Zan Li School of Physics, Northwest University, Xi'an, 710069 People's Republic of ChinaSearch for more papers by this authorSiyi Wang, Siyi Wang School of Physics, Northwest University, Xi'an, 710069 People's Republic of ChinaSearch for more papers by this authorYinhao Huang, Yinhao Huang School of Physics, Northwest University, Xi'an, 710069 People's Republic of ChinaSearch for more papers by this authorYang Jiao, Yang Jiao School of Physics, Northwest University, Xi'an, 710069 People's Republic of ChinaSearch for more papers by this authorHebao Yao, Hebao Yao School of Physics, Northwest University, Xi'an, 710069 People's Republic of ChinaSearch for more papers by this author Dong Pan, Dong Pan School of Physics, Northwest University, Xi'an, 710069 People's Republic of ChinaSearch for more papers by this authorHaibo Fan, Corresponding Author Haibo Fan hbfan@nwu.edu.cn School of Physics, Northwest University, Xi'an, 710069 People's Republic of ChinaSearch for more papers by this authorZan Li, Zan Li School of Physics, Northwest University, Xi'an, 710069 People's Republic of ChinaSearch for more papers by this authorSiyi Wang, Siyi Wang School of Physics, Northwest University, Xi'an, 710069 People's Republic of ChinaSearch for more papers by this authorYinhao Huang, Yinhao Huang School of Physics, Northwest University, Xi'an, 710069 People's Republic of ChinaSearch for more papers by this authorYang Jiao, Yang Jiao School of Physics, Northwest University, Xi'an, 710069 People's Republic of ChinaSearch for more papers by this authorHebao Yao, Hebao Yao School of Physics, Northwest University, Xi'an, 710069 People's Republic of ChinaSearch for more papers by this author First published: 01 February 2017 https://doi.org/10.1049/mnl.2016.0550Citations: 8AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Abstract Titanium dioxide (TiO2) thin films were successfully grown on glass (TiO2/glass) and fluorine tin oxide (TiO2/FTO) substrates by using radio frequency magnetron sputtering. The as-prepared films were characterised and compared by X-ray diffraction, scanning electron microscopy, atomic force microscopy, ultraviolet–visible spectroscopy and photocatalytic test. It was found that the film deposited on FTO has better crystallinity, rougher superficial morphology, narrower optical bandgap and higher photocatalytic efficiency. The relationship between the factors and the photocatalytic performance has been analysed. Besides, it has been found that the internal electric field developed at the interface of TiO2/FTO may also play a positive effect on the improvement of the photocatalytic efficiency. 1 Introduction Titanium dioxide (TiO2) has received great attentions as a photocatalytic material owing to its excellent properties, such as photostability, strong oxidising power, non-toxicity, low cost and antibacterial effect [[1]-[6]]. There are three distinct polymorphs for TiO2: anatase, rutile and brookite [[7]]. The brookite phase is usually known as a non-photo-active titania. Anatase has been pointed out as having the best photocatalytic efficiency, and some authors have argued that a mixture of anatase and rutile could work better [[8]]. It is reported that anatase powder with a high degree of crystallinity with high surface area is important to improve the photocatalytic activity [[9]]. At present, two major roadblocks stand in the way of the TiO2 photocatalyst development: low solar energy utilisation (3–5% of total solar spectrum) and fast recombination of photogenerated electron–hole pairs after absorption of ultraviolet (UV) light. To figure out this particular problem, several strategies have been proposed in the past in order to enhance the photocatalytic activity of the TiO2, such as noble metal deposition [[10], [11]], non-metal doping with sulphur [[12]], nitrogen [[13]] or fluorine [[14]], surface modifications [[15]] and coupling with other metal oxides including WO3 [[16]], MoO3 [[17]], Fe2O3 [[18]], ZrO2 [[19]] and SnO2 [[20]]. Accordingly, numerous methods have been used to prepare the TiO2 photocatalyst, such as chemical vapour evaporation [[21]], liquid-phase deposition [[22]], pulsed laser deposition [[23]] and sol–gel processes [[24]]. Compared with these methods, magnetron sputtering has obvious well-controlled [[25]] and large-area coating advantages with a high rate and low cost [[26]]. By adjusting the sputtering parameters, the crystal structure [[27]] and the surface morphology [[28]] of the TiO2 film can be successfully modulated. Besides, with this method it is also convenient to introduce other metal or non-metal atoms into TiO2 matrix by sputtering pre-fabricated doped target to further extend the absorption edge to the visible light region [[29]]. When TiO2 powders are used as photocatalyst for the degeneration of pollutants in liquid, several practical problems in photochemical processing are apparent: (i) separation of the catalyst from the suspension after the reaction is difficult, (ii) the suspended particles tend to aggregate, especially when they are present at high concentrations and (iii) particulate suspensions are not easily applicable to continuous flow systems [[30]]. To avoid these technical problems, TiO2 catalysts can be prepared in film form which are always grown on supporting substrates, such as glass [[31]], silicon [[32]], indium tin oxide [[33]], sapphire [[34]], stainless steel [[35]], SrTiO3 [[36]], LaAlO3 [[37]] and fluorine tin oxide (FTO) [[38]]. However, the influence of substrate on structural properties and photocatalytic activity of TiO2 films has not been investigated so far. In this Letter, therefore, we have deposited the TiO2 thin films on the very two popular substrates, glass (TiO2/glass) and FTO (TiO2/FTO) substrates, using radio frequency (RF) magnetron sputtering to understand the role of the substrate effect. 2 Experimental 2.1 Preparation of thin films TiO2 thin films were prepared with RF magnetron sputtering on two types of substrates, quartz glass and commercial FTO substrates with a sheet resistivity of 8 Ω/square for 3 h at the same time. Prior to deposition, the substrates were ultrasonically cleaned in acetone and alcohol for 15 min, rinsed in deionised water and dried thereafter. A high-purity sintered TiO2 (99.99%) of 60 mm in diameter was used as the target, and pure Ar (99.999%) was used as the sputtering gas. The background pressure in the chamber was set at 1.9 × 10−4Pa, and the working pressure was 1.5 Pa. The substrates (2.5 × 4 cm2) were placed parallel to the sputtering target surface with substrate–target distance of 7 cm and held at 250 °C. The RF power for the TiO2 target was fixed at 220 W. Before each deposition, the target was pre-sputtered in Ar for 5 min to weed out the surface adsorption. 2.2 Characterisation The X-ray diffraction (XRD) patterns of the TiO2 thin films were obtained by a Rigaku D/MAX-3C X-ray diffractometer, using Cu Kα (λ = 1.5405 Å) radiation with 40 kV and 30 mA at a scanning rate of 0.02° per second in 2θ from 10° to 60°. The surface morphologies of the films were investigated by a JEOL JSM-6700F scanning electron microscope (SEM), and a MultiMode 8 atomic force microscopy (AFM). The UV–visible (UV–Vis) absorption spectra of the films were measured by a TU-1901 UV–Vis spectrophotometer. 2.3 Photocatalytic experiments The photocatalytic performance of the samples was evaluated by the photocatalytic decomposition of methyl orange (MO) dye solution at a concentration of 15 mg/l and a volume of 20 ml. Being a good and simple index it is widely used to investigate the effect of the thin film on the photocatalytic degradation of organic chemicals sensitised by TiO2 films. During the photocatalytic degradation process, the rectangular beaker of MO was kept at ambient temperature. All tests were carried out by using a Xenon lamp (6.615 W/m2)which emits both UV light and visible light. After illumination, the MO concentration was monitored by the UV–Vis spectrophotometer and determined from the absorbance at the wavelength of 464 nm, which is the characteristic absorption peak of MO. The degradation results were calculated as C/C0, where C0 is the initial concentration of MO and C is the temporal concentration after degradation. To investigate the time-dependent photocatalytic effect during the illumination, the solution was extracted a little volume by an interval of 30 min and its concentration was also monitored meanwhile. 3 Results and discussion Fig. 1 shows the dependence of XRD patterns of deposited films on two types of substrates. From Fig. 1a, the spectrum shows an irregular background noise and a broad-hump shape in the range from 20° to 30°, which is relative with the amorphous structure of the glass substrate. The characteristic peaks of anatase, rutile and brookite do not appear, which suggests that the film deposited on glass is amorphous. Fig. 1b shows the XRD patterns of TiO2 film grown on FTO substrate, in which the FTO substrate related diffraction peaks are labelled by asterisks. It is observed that the spectrum shows obvious diffraction peaks (101) and (200) together with weak (211) peak, which match well with the characteristic of anatase phase of TiO2 [[38]]. The TiO2 film grown on the FTO substrate has a high crystallinity, suggesting that the substrate nature can be one of the important factors that influence the film quality. In fact, the FTO substrate has the same tetragonal crystal structure with TiO2 [[39]], while glass is amorphous solids. Based on epitaxial principle, small lattice mismatch between anatase TiO2 and the FTO substrate may promote the crystallisation of the TiO2 thin films [[40]]. Fig. 1Open in figure viewerPowerPoint XRD patterns of TiO2 films grown on a Glass b FTO substrates To compare the morphological difference of the films grown on different substrates, the SEM micrographs for cross-sectional and surface morphologies of TiO2 films deposited on different substrates are presented in Fig. 2. From the cross-sectional images of Fig. 2a and c, it can be observed that the entire surface of the two substrates is covered very uniformly with TiO2 thin films. Both of the two film surfaces are very flat and the interfaces between the films and the substrates can be easily recognised. The thickness of the TiO2 film grown on glass is estimated to be around 500 nm while the value of that grown on FTO is about 750 nm, which illustrates that the film has a larger growth rate when it is deposited on the FTO substrate. This can be interpreted that the crystalline film has a higher growth rate than amorphous film because of its higher sticking probability and surface diffusion rate [[41], [42]]. From the top view in Fig. 2b and d, it is observed that rough surfaces with sharp protruding nodules are apparent in the both films, but the nodules of TiO2/glass are much smaller than that of TiO2/FTO in size, which is believed to be relative with the crystalline degree of the two TiO2 films. The big grain size of the TiO2/FTO sample should be ascribed to its crystalline nature, which is consistent with the results of XRD. Fig. 2Open in figure viewerPowerPoint SEM micrographs of TiO2/glass and TiO2/FTO a Cross-sectional view of TiO2/glass b Top view of TiO2/glass c Cross-sectional view of TiO2/FTO d Top view of TiO2/FTO To further understand the surface morphology of the films, two samples have been studied and compared by ex situ AFM after deposition. The surface roughness has been quantitatively calculated by the root-mean-squared roughness (rms. roughness: ). is given by the standard deviation of the data from AFM images, and determined using the standard definition as follows (1) where represents the height of the data, is the mean height in AFM topography and N the number of pixels in the image region. As a result, the for TiO2/glass and TiO2/FTO is about 7.95 and 10.90 nm, respectively. The value for glass substrate is nearly one half of that (17.0 nm) for the film prepared by metal-organic-chemical-vapour-deposition (MOCVD) technique [[43]]. We ascribe this phenomenon to the higher growth rate of MOCVD, which is almost six times larger than our present case. As shown in Fig. 3, the TiO2/FTO exhibits bigger grains in size than TiO2/glass, that is to say the film deposited by RF sputtering is rougher for FTO substrates than for glass substrates, which coincides well with the observation from SEM images. Fig. 3Open in figure viewerPowerPoint AFM images for the film grown on different substrates a TiO2/glass b TiO2/FTO The UV–Vis absorption spectra of as-prepared TiO2 films on glass and FTO substrates were shown in Fig. 4a. Before the detection, the absorption of bare glass and FTO substrate has been recorded first and deducted thereafter. In contrast to TiO2/glass, TiO2/FTO has higher absorption in visible light region. Furthermore, a noticeable shift of the absorption shoulder into the visible light region is observed for TiO2/FTO. The optical bandgap value is a quite significant criteria for the selection of the TiO2 film applications [[44]]. TiO2 is an indirect semiconductor [[45]] and its bandgap can be estimated from the tangent lines in the plots of the following equation [[46], [47]]: (2) where is the optical bandgap, is absorption coefficient, is the photon energy, B is a parameter independent of photon energy for respective transitions. By plotting , can be obtained. As shown in Fig. 4b, the of TiO2/FTO and TiO2/glass can be estimated to be 3.08 and 3.16 eV, respectively. TiO2 photocatalyst with narrower bandgap is more efficient because it can absorb a broader range of light waves [[48]], so that is mean TiO2/FTO should have a higher photocatalytic efficiency than TiO2/glass. Such result can be further confirmed by the photocatalytic experiments. Fig. 4Open in figure viewerPowerPoint UV–Vis absorption spectra of as-prepared TiO2 films on glass and FTO substrates a Absorption spectra of as-prepared TiO2 films b Tauc-plots of (αhν)1/2 against hν for as-prepared TiO2 films The photocatalytic activities of all the samples were evaluated by the degradation of the typical organic contaminant MO under UV illumination. Fig. 5a displays the temporal evolution of the spectral changes taking place during the photodegradation of MO over the TiO2/FTO films. According to the Lamber–Beer's law, the lower the peak intensity of the absorption spectrum of the solution after irradiation, the higher photocatalytic efficiency will be. As can be seen from the image, the absorption peaks corresponding to MO steadily decreases with increasing reaction time, implying the photocatalytic activity of TiO2/FTO film. Fig. 5b shows the degradation versus time decay results for the two different reaction systems. Being a reference, the degradation of MO over blank (MO without any catalyst under UV light) is also presented. It can be easily observed that TiO2/FTO film exhibits more efficient photocatalytic activity compared with TiO2/glass film. Fig. 5Open in figure viewerPowerPoint Temporal evolution of the spectral changes taking place during the photodegradation of MO over the TiO2/FTO films a Absorption spectra of MO dye solution over the FTO/TiO2 sample under different times b Degradation against time decay curves of MO dye solution under three samples From above, we can conclude that the substrate plays a key role in the growth of TiO2 film by sputtering technique. Compared with TiO2/glass, TiO2/FTO film has several following advantages which prove that it is a better choice to be an efficient film photocatalyst. First, it has a higher crystal quality, which can facilitate the generation and separation of electron–hole pairs. Second, it has a rougher surface morphology with microcolumnar structure and consequently a large specific surface area, which can improve the reaction efficiency during the photocatalytic process. Lastly, it has a narrower bandgap, which extends the absorption active range of the sunlight. Besides, the bandenergy alignment at the interface of the TiO2/FTO heterostructure may also make positive contribution to the photocatalytic activity. The work function of TiO2 () has been determined from UV photoelectron spectroscopy to be 3.8 ± 0.1 eV [[49]]. As for FTO, to achieve an adequate conductivity, it is always degenerately doped. Recent theory and experiment have shown that the position of the Fermi level in degenerated doped FTO is above the valence band maximum and nearly independent of the doping level [[50]]. Using X-ray photoelectron spectroscopy, the work function of FTO (WFTO) has been measured to be 5.0 ± 0.1 eV [[51]]. In consideration of the metallic property of the FTO, the bandenergy alignment at the interface of TiO2 and FTO can be drawn up according to the Schottky–Mott theory [[52]], as shown in Fig. 6. After contact, electrons from the conduction band of TiO2, which have higher energy than the FTO electrons, flow into FTO till the Fermi level on the two sides is brought into coincidence. Thus, an electron depletion region and bent conduction band form on the TiO2 side near the interface, which consequently induce an electric field established from TiO2 to FTO. The amount of band bending is given by , where Vbb is expressed in volts and is known as the built-in potential or the band bending potential of the junction. Due to the internal electric field developed at TiO2/FTO, the photogenerated electron–hole pair can be separated effectively during the photocatalytic process, which will definitely improve the photocatalytic efficiency of the TiO2 film. Fig. 6Open in figure viewerPowerPoint Schematic diagram of energy band alignment at TiO2/FTO interfaces. , , , and are vacuum level, conduction band maximum, valence band maximum, Fermi level and energy bandgap, respectively. refers to band bending at the interface of TiO2 and FTO 4 Conclusion In summary, TiO2 thin films grown on two types of substrates were prepared by RF magnetron sputtering method. It has been demonstrated experimentally that substrate has an obvious effect on the structural, morphological, optical and photocatalytic properties of the TiO2 thin films. The TiO2/FTO film has better crystallinity, rougher superficial morphology and narrower optical bandgap, which are all positive to help TiO2 film acquire high photocatalytic performance. Besides, the internal electric field, developed at the interface of TiO2/FTO, facilitates the separation of the photogenerated electron–hole pair and thus can further improve the photocatalytic efficiency of the TiO2 film. This Letter suggests that FTO substrate is a promising candidate to prepare TiO2 film with high photocatalytic property, especially in large-area material growth and device commercial production. 5 Acknowledgment This work was supported by the National Natural Science Foundation of China (grant no. 11204238), the National Basic Science Personnel Training Fund (grant no. J0103) and the Natural Science Foundation of Shaanxi Educational Committee, China (grant no. 09JK740). 6 References [1]Yu J.C. Ho W. Lin J. et al.: ‘Photocatalytic activity, antibacterial effect, and photoinduced hydrophilicity of TiO2 films coated on a stainless steel substrate’, Environ. Sci. Technol., 2003, 37, (10), pp. 2296– 2301 (doi: 10.1021/es0259483) [2]Liang Y. Wang H. Casalongue H.S. et al.: ‘TiO2 nanocrystals grown on graphene as advanced photocatalytic hybrid materials’, Nano Res., 2010, 3, (10), pp. 701– 705 (doi: 10.1007/s12274-010-0033-5) [3]Wang P. Liu Z. Lin F. et al.: ‘Optimizing photoelectrochemical properties of TiO2 by chemical codoping’, Phys. Rev. B, 2010, 82, (19), p. 193103 (doi: 10.1103/PhysRevB.82.193103) [4]Sunada K. Kikuchi Y. Hashimoto K. et al.: ‘Bactericidal and detoxification effects of TiO2 thin film photocatalysts’, Environ. Sci. Technol., 1998, 32, (5), pp. 726– 728 (doi: 10.1021/es970860o) [5]Wen T. Gao J. Shen J. et al.: ‘Preparation and characterization of TiO2 thin films by the sol–gel process’, J. Mater. Sci., 2001, 36, (24), pp. 5923– 5926 (doi: 10.1023/A:1012989012840) [6]Hoffmann M.R. Martin S.T. Choi W. et al.: ‘Environmental applications of semiconductor photocatalysis’, Chem. Rev., 1995, 95, (1), pp. 69– 96 (doi: 10.1021/cr00033a004) [7]Mo S.D. Ching W.Y.: ‘Electronic and optical properties of three phases of titanium dioxide: rutile, anatase, and brookite’, Phys. Rev. B, 1995, 51, (19), p. 13023 (doi: 10.1103/PhysRevB.51.13023) [8]Collins-Martínez V. López Ortiz A. Aguilar Elguézabal A.: ‘Influence of the anatase/rutile ratio on the TiO2 photocatalytic activity for the photodegradation of light hydrocarbons’, Int. J. Chem. React. Eng., 2007, 5, (1), p. A92 [9]Kim D.S. Kwak S.Y.: ‘The hydrothermal synthesis of mesoporous TiO2 with high crystallinity, thermal stability, large surface area, and enhanced photocatalytic activity’, Appl. Catal. A, 2007, 323, pp. 110– 118 (doi: 10.1016/j.apcata.2007.02.010) [10]Litter M.I.: ‘Heterogeneous photocatalysis: transition metal ions in photocatalytic systems’, Appl. Catal. B, 1999, 23, (2), pp. 89– 114 (doi: 10.1016/S0926-3373(99)00069-7) [11]Zhou W. Fu H.: ‘Mesoporous TiO2: preparation, doping, and as a composite for photocatalysis’, ChemCatChem, 2013, 5, (4), pp. 885– 894 (doi: 10.1002/cctc.201200519) [12]Pathakoti K. Morrow S. Han C. et al.: ‘Photoinactivation of Escherichia coli by sulfur-doped and nitrogen–fluorine-codoped TiO2 nanoparticles under solar simulated light and visible light irradiation’, Environ. Sci. Technol., 2013, 47, (17), pp. 9988– 9996 (doi: 10.1021/es401010g) [13]Lee M. Yun H.J. Yu S. et al.: ‘Enhancement in photocatalytic oxygen evolution via water oxidation under visible light on nitrogen-doped TiO2 nanorods with dominant reactive {102} facets’, Catal. Commun., 2014, 43, pp. 11– 15 (doi: 10.1016/j.catcom.2013.08.019) [14]Likodimos V. Han C. Pelaez M. et al.: ‘Anion-doped TiO2 nanocatalysts for water purification under visible light’, Ind. Eng. Chem. Res., 2013, 52, (39), pp. 13957– 13964 (doi: 10.1021/ie3034575) [15]Bizarro M. Tapia-Rodríguez M.A. Ojeda M.L. et al.: ‘Photocatalytic activity enhancement of TiO2 films by micro and nano-structured surface modification’, Appl. Surf. Sci., 2009, 255, (12), pp. 6274– 6278 (doi: 10.1016/j.apsusc.2009.01.094) [16]Leghari S.A.K. Sajjad S. Zhang J.: ‘Large mesoporous micro-spheres of WO3/TiO2 composite with enhanced visible light photo activity’, RSC Adv., 2013, 3, (35), pp. 15354– 15361 (doi: 10.1039/c3ra41782d) [17]Gutbrod K. Zollfrank C.: ‘The photocatalytic properties of Ti–Mo oxides prepared by a simple sol–gel route’, J. Sol–Gel Sci. Technol., 2013, 66, (1), pp. 112– 119 (doi: 10.1007/s10971-013-2973-1) [18]Tang H. Zhang D. Tang G. et al.: ‘Hydrothermal synthesis and visible-light photocatalytic activity of α-Fe2O3/TiO2 composite hollow microspheres’, Ceram. Int., 2013, 39, (8), pp. 8633– 8640 (doi: 10.1016/j.ceramint.2013.04.040) [19]Kokporka L. Onsuratoom S. Puangpetch T. et al.: ‘Sol–gel-synthesized mesoporous-assembled TiO2–ZrO2 mixed oxide nanocrystals and their photocatalytic sensitized H2 production activity under visible light irradiation’, Mater. Sci. Semicond. Process., 2013, 16, (3), pp. 667– 678 (doi: 10.1016/j.mssp.2012.12.007) [20]Kusior A. Klich-Kafel J. Trenczek-Zajac A. et al.: ‘TiO2–SnO2 nanomaterials for gas sensing and photocatalysis’, J. Eur. Ceram. Soc., 2013, 33, (12), pp. 2285– 2290 (doi: 10.1016/j.jeurceramsoc.2013.01.022) [21]Battiston G.A. Gerbasi R. Gregori A. et al.: ‘PECVD of amorphous TiO2 thin films: effect of growth temperature and plasma gas composition’, Thin Solid Films, 2000, 371, (1), pp. 126– 131 (doi: 10.1016/S0040-6090(00)00998-6) [22]Yu J.G. Yu H.G. Cheng B. et al.: ‘The effect of calcination temperature on the surface microstructure and photocatalytic activity of TiO2 thin films prepared by liquid phase deposition’, J. Phys. Chem. B, 2003, 107, (50), pp. 13871– 13879 (doi: 10.1021/jp036158y) [23]Yu J. Zhao X. Zhao Q.: ‘Effect of surface structure on photocatalytic activity of TiO2 thin films prepared by sol–gel method’, Thin Solid Films, 2000, 379, (1), pp. 7– 14 (doi: 10.1016/S0040-6090(00)01542-X) [24]Xu Y. Shen M.: ‘Fabrication of anatase-type TiO2 films by reactive pulsed laser deposition for photocatalyst application’, J. Mater. Process. Technol., 2008, 202, (1), pp. 301– 306 (doi: 10.1016/j.jmatprotec.2007.09.015) [25]Turkevych I. Pihosh Y. Goto M. et al.: ‘Photocatalytic properties of titanium dioxide sputtered on a nanostructured substrate’, Thin Solid Films, 2008, 516, (9), pp. 2387– 2391 (doi: 10.1016/j.tsf.2007.04.083) [26]Kruth A. Peglow S. Quade A. et al.: ‘Structural and photoelectrochemical properties of DC magnetron-sputtered TiO2 layers on FTO’, J. Phys. Chem. C, 2014, 118, (43), pp. 25234– 25244 (doi: 10.1021/jp507487c) [27]Okimura K. Shibata A. Maeda N. et al.: ‘Preparation of rutile TiO2 films by RF magnetron sputtering’, Jpn. J. Appl. Phys., 1995, 34, (9R), p. 4950 (doi: 10.1143/JJAP.34.4950) [28]Singh P. Kaur D.: ‘Room temperature growth of nanocrystalline anatase TiO2 thin films by dc magnetron sputtering’, Physica B, 2010, 405, (5), pp. 1258– 1266 (doi: 10.1016/j.physb.2009.11.061) [29]Zhang Z.P. Yu B. Fan H.B. et al.: ‘Visible-light photocatalytic properties of Mo–C codoped anatase TiO2 films prepared by magnetron sputtering’, J. Phys. Chem. Solids, 2015, 87, pp. 53– 57 (doi: 10.1016/j.jpcs.2015.08.001) [30]Sopyan I. Watanabe M. Murasawa S. et al.: ‘An efficient TiO2 thin-film photocatalyst: photocatalytic properties in gas-phase acetaldehyde degradation’, J. Photochem. Photobiol. A, 1996, 98, (1), pp. 79– 8698 (doi: 10.1016/1010-6030(96)04328-6) [31]Lin W.S. Huang C.H. Yang W.J. et al.: ‘Photocatalytic TiO2 films deposited by RF magnetron sputtering at different oxygen partial pressure’, Curr. Appl. Phys., 2010, 10, (6), pp. 1461– 1466 (doi: 10.1016/j.cap.2010.05.014) [32]Lee D.H. Cho Y.S. Yi W.I. et al.: ‘Metalorganic chemical vapor deposition of TiO2: N anatase thin film on Si substrate’, Appl. Phys. Lett., 1995, 66, (7), pp. 815– 816 (doi: 10.1063/1.113430) [33]Zuo J.: ‘Deposition of Ag nanostructures on TiO2 thin films by RF magnetron sputtering’, Appl. Surf. Sci., 2010, 256, (23), pp. 7096– 7101 (doi: 10.1016/j.apsusc.2010.05.034) [34]Luttrell T. Halpegamage S. Tao J. et al.: ‘Why is anatase a better photocatalyst than rutile?-Model studies on epitaxial TiO2 films’, Sci. Rep., 2014, 4, p. 4043 (doi: 10.1038/srep04043) [35]Zhu Y. Zhang L. Wang L. et al.: ‘The preparation and chemical structure of TiO2 film photocatalysts supported on stainless steel substrates via the sol–gel method’, J. Mater. Chem., 2001, 11, (7), pp. 1864– 1868 (doi: 10.1039/b100048i) [36]Kennedy R.J. Stampe P.A.: ‘The influence of lattice mismatch and film thickness on the growth of TiO2 on LaAlO3 and SrTiO3 substrates’, J. Cryst. Growth, 2003, 252, (1), pp. 333– 342 (doi: 10.1016/S0022-0248(02)02514-9) [37]Sasahara A. Droubay T.C. Chambers S.A. et al.: ‘Topography of anatase TiO2 film synthesized on LaAlO3 (001)’, Nanotechnology, 2005, 16, (3), p. S18 (doi: 10.1088/0957-4484/16/3/004) [38]Masuda Y. Kato K.: ‘Anatase TiO2 films crystallized on SnO2: F substrates in an aqueous solution’, Thin Solid Films, 2008, 516, (9), pp. 2547– 2552 (doi: 10.1016/j.tsf.2007.04.063) [39]Abd-Lefdil M. Diaz R. Bihri H. et al.: ‘Preparation and characterization of sprayed FTO thin films’, Eur. Phys. J. Appl. Phys., 2007, 38, (3), pp. 217– 219 (doi: 10.1051/epjap:2007090) [40]Luryi S. Suhir E.: ‘New approach to the high quality epitaxial growth of lattice-mismatched materials’, Appl. Phys. Lett., 1986, 49, (3), pp. 140– 142 (doi: 10.1063/1.97204) [41]Kajikawa Y.: ‘Texture development of non-epitaxial polycrystalline ZnO films’, J. Cryst. Growth, 2006, 289, (1), pp. 387– 394 (doi: 10.1016/j.jcrysgro.2005.11.089) [42]Kajikawa Y. Noda S. Komiyama H.: ‘Comprehensive perspective on the mechanism of preferred orientation in reactive-sputter-deposited nitrides’, J. Vac. Sci. Technol. A, 2003, 21, (6), pp. 1943– 1954 (doi: 10.1116/1.1619414) [43]Won D.J. Wang C.H. Jang H.K. et al.: ‘Effects of thermally induced anatase-to-rutile phase transition in MOCVD-grown TiO2 films on structural and optical properties’, Appl. Phys. A, 2001, 73, (5), pp. 595– 600 (doi: 10.1007/s003390100804) [44]Tanemura S. Miao L. Wunderlich W. et al.: ‘Fabrication and characterization of anatase/rutile–TiO2 thin films by magnetron sputtering: a review’, Sci. Technol. Adv. Mater., 2005, 6, (1), pp. 11– 17 (doi: 10.1016/j.stam.2004.06.003) [45]Irie H. Watanabe Y. Hashimoto K.: ‘Nitrogen-concentration dependence on photocatalytic activity of TiO2−xNx powders’, J. Phys. Chem. B, 2003, 107, (23), pp. 5483– 5486 (doi: 10.1021/jp030133h) [46]Lu J. Wang H. Dong S. et al.: ‘Effect of Ag shapes and surface compositions on the photocatalytic performance of Ag/ZnO nanorods’, J. Alloys Compd., 2014, 617, pp. 869– 876 (doi: 10.1016/j.jallcom.2014.08.096) [47]Meng F. Song X. Sun Z.: ‘Photocatalytic activity of TiO2 thin films deposited by RF magnetron sputtering’, Vacuum, 2009, 83, (9), pp. 1147– 1151 (doi: 10.1016/j.vacuum.2009.02.009) [48]Nagaveni K. Hegde M.S. Ravishankar N. et al.: ‘Synthesis and structure of nanocrystalline TiO2 with lower band gap showing high photocatalytic activity’, Langmuir, 2004, 20, (7), pp. 2900– 2907 (doi: 10.1021/la035777v) [49]Uddin M.T. Nicolas Y. Olivier C. et al.: ‘Preparation of RuO2/TiO2 mesoporous heterostructures and rationalization of their enhanced photocatalytic properties by band alignment investigations’, J. Phys. Chem. C, 2013, 117, (42), pp. 22098– 22110 (doi: 10.1021/jp407539c) [50]Canestraro C.D. Oliveira M.M. Valaski R. et al.: ‘Strong inter-conduction-band absorption in heavily fluorine doped tin oxide’, Appl. Surf. Sci., 2008, 255, (5), pp. 1874– 1879 (doi: 10.1016/j.apsusc.2008.06.113) [51]Helander M.G. Greiner M.T. Wang Z.B. et al.: ‘Work function of fluorine doped tin oxide’, J. Vac. Sci. Technol. A, 2011, 29, (1), p. 011019 (doi: 10.1116/1.3525641) [52]Sharma B.L.: ‘ Metal-semiconductor Schottky barrier junctions and their applications’ ( Springer Science & Business Media, NY, 2013) Citing Literature Volume12, Issue2February 2017Pages 82-86 FiguresReferencesRelatedInformation
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