WorldWideScience

Sample records for tio2 thin films

  1. TiO2 thin film photocatalyst

    YU Jiaguo

    2004-01-01

    It is well known that the photocatalytic activity of TiO2 thin films strongly depends on the preparing methods and post-treatment conditions, since they have a decisive influence on the chemical and physical properties of TiO2 thin films.Therefore, it is necessary to elucidate the influence of the preparation process and post-treatment conditions on the photocatalytic activity and surface microstructures of the films. This review deals with the preparation of TiO2 thin film photocatalysts by wet-chemical methods (such as sol-gel, reverse micellar and liquid phase deposition) and the comparison of various preparation methods as well as their advantage and disadvantage. Furthermore, it is discussed that the advancement of photocatalytic activity, super-hydrophilicity and bactericidal activity of TiO2 thin film photocatalyst in recent years.

  2. Superhydrophilicity of TiO2 nano thin films

    Full text: Among the several oxide semiconductors, titanium dioxide has a more helpful role in our environmental purification due to its photocatalytic activity, photo-induced superhydrophilicity, and as a result of them non-toxicity, self cleaning, and antifogging effects. After the discovery of superhydrophilicity of titanium dioxide in 1997, several researches have been performed due to its nature and useful applications. The superhydrophilicity property of the surface allows water to spread completely across the surface rather than remains as droplets, thus making the surface antifog and easy-to-clean. The distinction of photo-induced catalytic and hydrophilicity properties of TiO2 thin films has been accepted although, the origin of hydrophilicity property has not been recognized completely yet. TiO2 thin films on soda lime glass were prepared by the sol-gel method and spin coating process. The calcination temperature was changed from 100 to 550 C. XRD patterns show increasing the content of polycrystalline anatase phase with increasing the calcination temperature. The AFM results indicate granular morphology of the films, which particle size changes from 22 to 166 nm by increasing the calcination temperature. The RBS, EDX and Raman spectroscopy of the films show the ratio of Ti:O∼0.5, and diffusion of sodium ions from substrate into the layer, by increasing the calcination temperature. The UV/Vis. spectroscopy of the films indicates a red shift by increasing the calcination temperature. The contact angle meter experiment shows that superhydrophilicity of the films depends on the formation of anatase crystal structure and diffused sodium content from substrate to the layer. The best hydrophilicity property was observed at 450 C calcination temperature, where the film is converted to a superhydrophilic surface after 10 minutes under 2mW/cm2 UV irradiation. TiO2 thin film on Si(111), Si(100), and quartz substrates needs less time to be converted to

  3. Birefringence enhancement in annealed TiO2 thin films

    van Popta, Andy C.; Cheng, June; Sit, Jeremy C.; Brett, Michael J.

    2007-07-01

    Postdeposition thermal annealing is used to enhance the form birefringence of nanostructured TiO2 thin films grown by electron-beam evaporation using the serial bideposition technique. Thin films were grown on fused silica substrates using oblique deposition angles between 60° and 75° and repetitive 180° substrate rotations to produce birefringent thin films that are structurally anisotropic. Postdeposition annealing in air, between 200 and 900°C, was used to increase the form birefringence of the films by changing the TiO2 phase from the as-deposited amorphous state to a polycrystalline state that exhibits a greater inherent density and larger bulk refractive index. The optical properties, microstructure, and crystallinity were characterized by Mueller matrix ellipsometry, scanning electron microscopy, atomic force microscopy, and x-ray diffraction. It was found that the in-plane birefringence increased significantly upon thermal annealing, in some cases yielding birefringence values that doubled in magnitude, from 0.11 to 0.22 at a wavelength of 550nm for films annealed at 400°C.

  4. Properties of TiO2 Thin Films Prepared by Magnetron Sputtering

    2002-01-01

    With rapid progressive application of TiO2 thin films, magnetron sputtering becomes a very interesting method to prepare such multi-functional thin films. This paper focuses on influences of various deposition processes and deposition rate on the structures and properties of TiO2 thin films. Anatase, rutile or amorphous TiO2 films with various crystalline structures and different photocatalytic, optical and electrical properties can be produced by varying sputtering gases, substrate temperature, annealing process, deposition rate and the characteristics of magnetron sputtering. This may in turn affect the functions of TiO2 films in many applications. Furthermore, TiO2-based composites films can overcome many limitations and improve the properties of TiO2 films.

  5. Effect of Microstructure of TiO2 Thin Films on Optical Band Gap Energy

    TIAN Guang-Lei; HE Hong-Bo; SHAO Jian-Da

    2005-01-01

    @@ TiO2 coatings are prepared on fused silica with conventional electron beam evaporation deposition. After annealed at different temperatures for four hours, the spectra and XRD patterns of TiO2 thin film are obtained. XRD patterns reveal that only anatase phase can be observed in TiO2 coatings regardless of the different annealing temperatures, and with the increasing annealing temperature, the grain size gradually increases. The relationship between the energy gap and microstructure of anatase is determined and discussed. The quantum confinement effect is observed that with the increasing grain size of TiO2 thin film, the band gap energy shifts from 3.4eV to 3.21 eV. Moreover, other possible influence of the TiO2 thin-film microstructure, such as surface roughness and thin film absorption, on band gap energy is also expected.

  6. Thin nanostructured crystalline TiO 2 films and their applications in solar cells

    Cheng, Yajun

    2007-01-01

    Research on thin nanostructured crystalline TiO2 films has attracted considerable interests because of their intriguing physical properties and potential applications in photovoltaics. Nanostructured TiO2 film plays an important role in the TiO2 based dye-sensitized solar cells because they act as a substrate for the adsorption of dye molecules and a matrix for the transportation of electrons as well. Thus they can influence the solar cell performance significantly. Consequently, the control ...

  7. A Novel Synthesis of Two-dimensional Nanopatterned TiO2 Thin Film

    Ming Xian LIU; Li Hua GAN; Gen CHEN; Zi Jie XU; Zhi Xian HAO; Long Wu CHEN

    2006-01-01

    A novel two-dimensional nanopatterned TiO2 thin film has been synthesized through the interaction between cationic Gemini surfactant molecules and the prepared TiO2 colloid nanoparticles with average diameters of 8 nm by controlling the surface pressure of the monolayer. TEM photographs from the formed Gemini-TiO2 composite monolayer confirm that the prepared TiO2 film is of a branch nanopattem.

  8. Photocatalytic activity study of TiO2 thin films with and without Fe ion implantation

    Transparent and colourless TiO2 thin films were fabricated on microscope glass slides by d.c. magnetron reactive sputtering method using Ar and O2 as working gases. Then Fe ions were implanted into the TiO2 thin film to observe its effects on the photocatalytic activity. X-ray diffraction, X-ray photoelectron spectroscopy and UV-Vis-NIR spectrophotometer technologies were used to characterize the films. The photocatalytic activities of the samples were evaluated by the degradation of Rhodamine B dye. The effects of Fe ion implantation on the decrease in the photocatalytic activity of the TiO2 thin film were discussed

  9. Photoinduced properties of nanocrystalline TiO2 sol–gel derived thin films

    Akbar Eshaghi; Mahmoud Pakshir; Reza Mozaffarinia

    2010-08-01

    In this paper, nanostructure TiO2 thin films were deposited on glass substrates by sol–gel dip coating technique. X-ray diffraction and Fourier transform infrared spectroscopy were used to determine film behaviour. The super-hydrophilicity was assessed by contact angle measurement. Photocatalytic properties of these films were evaluated by degradation of methylene blue under UV irradiation. The XRD pattern of TiO2 powder samples confirmed the presence of polycrystalline anatase phase with a crystal size of 17 nm. The results indicated that UV light irradiation had significant effect on super-hydrophilic and photocatalytic properties of TiO2 thin films.

  10. PHOTOCATALYTIC DEGRADATION OF WASTE WATER ON. THIN FILMS OF TiO2

    Wu Zhenghuang

    2001-01-01

    The degradation of organic phosphorous pesticide waste water using thin films of TiO2, which was prepared in an atmospheric vertical chemical vapor deposition system, was studied. The results show that the wafer material for coating TiO2, the photocatalytic time, the TiO2 crystal phase, the pH value and the concentration of pesticides in waste water influence the degradation rate. These facts indicate some potential for photocatalytic treatment of waste water by utilizing sunlight.

  11. On the Crystal Structural Control of Sputtered TiO2 Thin Films.

    Jia, Junjun; Yamamoto, Haruka; Okajima, Toshihiro; Shigesato, Yuzo

    2016-12-01

    In this study, we focused on the origin on the selective deposition of rutile and anatase TiO2 thin films during the sputtering process. The observation on microstructural evolution of the TiO2 films by transmission electron microscopy revealed the coexistence of rutile and anatase TiO2 phases in the initial stage under the preferential growth conditions for the anatase TiO2; the observations further revealed that the anatase phase gradually dominated the crystal structure with increasing film thickness. These results suggest that the bombardment during the sputtering deposition did not obviously affect the TiO2 crystal structure, and this was also confirmed by off-axis magnetron sputtering experiments. We also investigated the mechanism of the effect of Sn impurity doping on the crystal structure using first-principles calculations. It is found that the formation energy of Sn-doped rutile TiO2 is lower than that of Sn-doped anatase TiO2; this suggests that the Sn-doped TiO2 favours the rutile phase. These results offer a guideline for the utilization of selective deposition of rutile and anatase TiO2 thin films in various industrial applications. PMID:27389344

  12. On the Crystal Structural Control of Sputtered TiO2 Thin Films

    Jia, Junjun; Yamamoto, Haruka; Okajima, Toshihiro; Shigesato, Yuzo

    2016-07-01

    In this study, we focused on the origin on the selective deposition of rutile and anatase TiO2 thin films during the sputtering process. The observation on microstructural evolution of the TiO2 films by transmission electron microscopy revealed the coexistence of rutile and anatase TiO2 phases in the initial stage under the preferential growth conditions for the anatase TiO2; the observations further revealed that the anatase phase gradually dominated the crystal structure with increasing film thickness. These results suggest that the bombardment during the sputtering deposition did not obviously affect the TiO2 crystal structure, and this was also confirmed by off-axis magnetron sputtering experiments. We also investigated the mechanism of the effect of Sn impurity doping on the crystal structure using first-principles calculations. It is found that the formation energy of Sn-doped rutile TiO2 is lower than that of Sn-doped anatase TiO2; this suggests that the Sn-doped TiO2 favours the rutile phase. These results offer a guideline for the utilization of selective deposition of rutile and anatase TiO2 thin films in various industrial applications.

  13. Deposition of Co-doped TiO2 Thin Films by sol-gel method

    Boutlala, A.; Bourfaa, F.; Mahtili, M.; Bouaballou, A.

    2016-03-01

    Cobalt doped TiO2 thin films have been prepared by sol-gel method onto glass substrate at room temperature. in this present work, we are interesting to study the effect of Cobalt doped TiO2 thin films.the concentration of Co was varied from 0 to 6%at .The obtained films have been annealed at 500°C for 2 hours. X-ray diffraction patterns showed that Co: TiO2 films are polycrystalline with a tetragonal anatase and orthorhombic brookite types structures. The surface morphologies of the TiO2 doped with cobalt thin films were evaluated by Atomic Force Microscopy (AFM). The optical properties were studied by mean of UV-visible and near infrared spectroscopy.The calculated optical band gap decreases from 3.30 to 2.96 eV with increasing Co doping.

  14. Preparation and antibacterial behavior of Fe3+-doped nanostructured TiO2 thin films

    Fe3+-doped nanostructured TiO2 thin films with antibacterial activity were prepared on soda-lime-silica glass slides by using sol-gel technology. Water containing Escherichia coli K-12 with TiO2 thin films in was exposed to low intensity fluorescent light and antibacterial efficiency was evaluated with spread plate techniques. The films are porous and have anatase phase. Iron ions increased luminous energy utilization as the absorption edge of the Fe3+-doped film has a red shift compared to that of the pure TiO2 film in the UV-VIS absorption spectrum. The bacterial removal efficiency reached 95% at the optimum concentration of iron ion (about 0.5% (mol)) after 120 min irradiation. The antibacterial behavior of the doped TiO2 films was explicitly observed using scanning electron microscopy and cell wall damage was found

  15. Fabrication and characterization of nano TiO2 thin films at low temperature

    Anatase TiO2 thin films were successfully prepared on glass slide substrates via a sol-gel method from refluxed sol (RS) containing anatase TiO2 crystals at low temperature of 100 deg. C. The influences of various refluxing time on crystallinity, morphology and size of the RS sol and dried TiO2 films particles were discussed. These samples were characterized by infrared absorption spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission-scanning electron microscopy (FE-SEM) and UV-vis absorption spectroscopy (UV-vis). The photocatalytic activities of the TiO2 thin films were assessed by the degradation of methyl orange in aqueous solution. The results indicated that titania films thus obtained were transparent and their maximal light transmittance exceeded 80% under visible light region. The TiO2 thin films prepared from RS-6 sol showed the highest photocatalytic activity, when the calcination temperature is higher than 300 deg. C. The degradation of methyl orange of RS-6 thin films reached 99% after irradiated for 120 min, the results suggested that the TiO2 thin films prepared from RS sol exhibited high photoactivities

  16. Photocatalytic properties of TiO2 thin films obtained by glancing angle deposition

    Titanium dioxide (TiO2) thin films with different nanostructures such as nano-particles and separated vertical columns were grown by glancing angle deposition (GLAD) in an electron beam evaporation system. The photocatalytic properties of grown TiO2 films with different deposition angles and different annealing temperatures were evaluated by following decomposition of methyl orange under ultraviolet (UV) light irradiation. The results suggest that increased surface area due to the GLAD process could improve the photocatalytic properties of TiO2 films.

  17. Effects of annealed temperature on the properties of TiO2 thin films

    Kumar, Avesh

    2016-05-01

    In this work, the structural, morphological and electrical properties of TiO2 thin films are studied. The phase transformation of TiO2 from anatase to rutile is occurred at a certain temperature. This transformation increases defects concentration onthe surface of the film which acts as trapping sites for carriers, thereby affecting the Fermi level of TiO2 film.Quantitative estimation of Fermi level shifting is measured in terms of work function measurement using scanning Kelvin probe measurement. Work function of TiO2 was found to decrease with increasing annealed temperature indicating shifting of Fermi level towards conduction band. Position of Fermi level plays an important role in phase transformation and electronic properties of TiO2.

  18. Controlling the particle size of nanobrookite TiO2 thin films

    Highlights: → Nanobrookite TiO2 films were deposited on glass substrates by spin-coating method. → We produced the pure nanobrookite films using titanium butoxide and acetic acid. → Particle size of the TiO2 films was controlled by volume ratios of water:acid. → We determined that it is possible to obtain the films with single orientation. → Particle sizes of the TiO2 films decrease with the decreasing water:AcAc volume ratio. → It has been found that the spectrum red-shifts with increasing water concentration. - Abstract: In this study, pure nanobrookite TiO2 thin films were successfully deposited on glass substrates with the spin-coating method using titanium butoxide and acetic acid. The particle size of TiO2 films was controlled by the water:AcAc volume ratio. This study shows that it is possible to obtain single oriented pure brookite films. The structural and optical properties of the nanobrookite TiO2 thin films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), spectrophotometer (NKD), and Fourier transform infrared spectrometer (FTIR).

  19. EFFECT OF ZnFe2O4 DOPING ON THE OPTICALPROPERTIES OF TiO2 THIN FILMS

    李广海; 吴玉程; 张立德

    2001-01-01

    Amorphous TiO2 thin films and ZnFe2O4-doped TiO2 composite films were deposited by radio frequency magnetron sputtering. The effect of ZnFe2O4 doping on the optical properties of TiO2 thin films was reported. Our results show that the absorption edge of TiO2 thin films and composite films exhibits a blueshift with decreasing annealing temperature. The absorption edge of composite films has moved to a visible spectrum range, and a very large redshift occurs in comparison with TiO2 thin films. An enhanced photoluminescence was observed in ZnFe2O4-doped anatase TiO2 thin films at room temperature.

  20. Superhydrophilic graphene-loaded TiO2 thin film for self-cleaning applications.

    Anandan, Srinivasan; Rao, Tata Narasinga; Sathish, Marappan; Rangappa, Dinesh; Honma, Itaru; Miyauchi, Masahiro

    2013-01-01

    We develop a simple approach to fabricate graphene-loaded TiO(2) thin films on glass substrates by the spin-coating technique. Our graphene-loaded TiO(2) films were highly conductive and transparent and showed enhanced photocatalytic activities. More significantly, graphene/TiO(2) films displayed superhydrophilicity within a short time even under a white fluorescent light bulb, as compared to a pure TiO(2) film. The enhanced photocatalytic activity of graphene/TiO(2) films is attributed to its efficient charge separation, owing to electrons injection from the conduction band of TiO(2) to graphene. The electroconductivity of the graphene-loaded TiO(2) thin film also contributes to the self-cleaning function by its antifouling effect against particulate contaminants. The present study reveals the ability of graphene as a low cost cocatalyst instead of expensive noble metals (Pt, Pd), and further shows its capability for the application of self-cleaning coatings with transparency. The promising characteristics of (inexpensive, transparent, conductive, superhydrophilic, and highly photocatalytically active) graphene-loaded TiO(2) films may have the potential use in various indoor applications. PMID:23240759

  1. Magnetic and electrical properties of TiO2:Nb thin films

    Yu, Chang-Feng; Sun, Shih-Jye; Chen, Jian-Ming

    2014-02-01

    This study investigated the electrical and especially the magnetic properties of Niobium (Nb) doped TiO2 (TiO2:Nb) thin films. Experiments evidently present that both minimum of ferromagnetism and resistivity exist in a same Nb doping ratio (3.0%). The XPS experiments revealed that Nb doping simultaneously increases and compensates for oxygen vacancies. The proposed model explains magnetic and electrical properties by analyzing oxygen vacancies induced by vacuum annealing or by Nb doping.

  2. Application of Pcvd Process to Uniform Coating of TiO2 Thin Films on Polypropylene Beads

    Kim, Dong-Joo; Pham, Hung Cuong; Kim, Kyo-Seon

    The growth of the TiO2 thin films coated on the polypropylene beads was analyzed experimentally in a rotating cylindrical plasma chemical vapor deposition (PCVD) reactor. The precursors for the thin films were generated by plasma reactions, and they deposited on the polypropylene beads to become the uniform thin films. The TiO2 thin films grow more quickly on the polypropylene beads by increasing the mass flow rate of TTIP, or the rotation speed of the reactor. The smaller number of polypropylene beads in the reactor increases the growth rate of the thin films. The high-quality TiO2 thin films can be coated on particles uniformly by using the rotating cylindrical PCVD process. The particles coated with high-quality TiO2 thin films can be applied to the removal of air and water pollutants by a photodegradation reaction of TiO2.

  3. Visible-light photocatalytic activity of nitrided TiO2 thin films

    TiO2 thin films have been applied in UV-light photocatalysis. Nevertheless visible-light photocatalytic activity would make this material more attractive for applications. In this work we present results on the modification of titanium oxide (anatase) sol-gel thin films, via a nitriding process using a microwave plasma source. After the treatment in the nitrogen plasma, the nitrogen content in the TiO2 films varied in the range from 14 up to 28 at%. The titanium oxide films and the nitrided ones were characterized by XPS, micro-Raman spectroscopy and UV-vis spectroscopy. Photocatalytic activity tests were done using a Methylene Blue dye solution, and as catalyst TiO2 and nitrided TiO2 films. The irradiation of films was carried out with a lamp with emission in the visible (without UV). The results showed that the nitrided TiO2 films had photocatalytic activity, while the unnitrided films did not.

  4. Preparation and antimicrobial assay of ceramic brackets coated with TiO2 thin films

    Cao, Shuai; Wang, Ye; Cao, Lin; Wang, Yu; Lin, Bingpeng; Lan, Wei

    2016-01-01

    Objective Different methods have been utilized to prevent enamel demineralization and other complications during orthodontic treatment. However, none of these methods can offer long-lasting and effective prevention of orthodontic complications or interventions after complications occur. Considering the photocatalytic effect of TiO2 on organic compounds, we hoped to synthesize a novel bracket with a TiO2 thin film to develop a photocatalytic antimicrobial effect. Methods The sol-gel dip coating method was used to prepare TiO2 thin films on ceramic bracket surfaces. Twenty groups of samples were composed according to the experimental parameters. Crystalline structure and surface morphology were characterized by X-ray diffraction and scanning electron microscopy, respectively; film thickness was examined with a surface ellipsometer. The photocatalytic properties under ultraviolet (UV) light irradiation were analyzed by evaluating the degradation ratio of methylene blue (MB) at a certain time. Antibacterial activities of selected thin films were also tested against Lactobacillus acidophilus and Candida albicans. Results Films with 5 coating layers annealed at 700℃ showed the greatest photocatalytic activity in terms of MB decomposition under UV light irradiation. TiO2 thin films with 5 coating layers annealed at 700℃ exhibited the greatest antimicrobial activity under UV-A light irradiation. Conclusions These results provide promising guidance in prevention of demineralization by increasing antimicrobial activities of film coated brackets. PMID:27226960

  5. Optical properties of TiO2 thin films after Ag ion implantation

    Metal plasma ion implantation has being successfully developed for improving the electronic and optical properties of semiconductor materials. Prior to deposition, a TiO2 colloidal suspension was synthesized by microwave-induced thermal hydrolysis of the titanium tetrachloride aqueous solution. The TiO2 thin film was optimized to obtain a high-purity crystalline anatase phase by calcinations at 550 deg. C. The TiO2 coating was uniform without aggregation, which provided good photo conversion efficiency. Ag ion implantation into the as-calcined TiO2 thin films was conducted with 1 x 1015 ∼ 1 x 1016 ions/cm2 at 40 keV. The peak position and intensity of the photoluminescence and UV-Vis absorption spectra are quite sensitive to Ag doping. The optical characterization showed a shift in optical absorption wavelength towards infrared ray side, which was correlated with the structure variation of the Ag+ implanted TiO2. Due to the strong capability of forming compounds between the energetic silver ions and TiO2, the photoluminescence emission and UV-Vis absorption efficiencies were improved.

  6. A versatile new method for synthesis and deposition of doped, visible light-activated TiO2 thin films

    In, Su-il; Kean, A.H.; Orlov, A.; Tikhov, M.S.; Lambert, R.M.

    2009-01-01

    A flexible and widely applicable method allows the deposition of carbon-doped visible light-activated photocatalytic TiO2 thin films on a variety of substrates.......A flexible and widely applicable method allows the deposition of carbon-doped visible light-activated photocatalytic TiO2 thin films on a variety of substrates....

  7. Uniform coating of TiO2 thin films on particles by rotating cylindrical PCVD reactor.

    Kim, Dong-Joo; Baeg, Jin-Ook; Moon, Sang-Jin; Kim, Kyo-Seon

    2009-07-01

    We analyzed TiO2 thin film growth on glass particles in a rotating cylindrical plasma chemical vapor deposition (PCVD) reactor and numerically investigated the effects of several process variables on the film growth. An increase in titanium tetra-isopropoxide (TTIP) or O2 partial pressure can enhance the film growth rate on the particles because the concentration of TiO(x), which is the main precursor for thin film growth, becomes higher in the reactor. As the particle diameter decreases, the TiO(x) concentration increases and the thin film on the particles grows more quickly. The neutral-radical reaction between TTIP and O radicals for TiO(x) generation in TTIP + O2 plasmas can be important to enhance the thin film growth rate on the particles. The growth rate of TiO2 film predicted in this study was 1 approximately 20 nm/min, which is in good agreement with the published experimental results. This study suggests that a uniform TiO2 thin film on particles can be obtained by using a rotating cylindrical PCVD reactor. PMID:19916444

  8. Characterization of TiO2 Thin Films on Glass Substrate Growth Using DC Sputtering Technique

    It has been fabricated and characterization a TiO2 thin films deposited on glass substrate using DC sputtering technique. Fabrication of TiO2 thin films were carried out at electrode voltage 4 kV, sputtering current 5 mA, vacuum pressure 5 x 10-4 torr, deposition time 150 minutes, and temperature of the substrate were varied from 150 -350 oC, while as a gas sputter was argon. The results was tested their micro structure using SEM, and crystal structure using XRD and found that the crystal structure of TiO2 powder before deposited on glass substrate was rutile and anatase with orientation (110) and (200) for anatase and (100) and (111) rutile structure. While the crystal structure which deposited at temperature 150 oC and deposition time 2.5 hours was anatase with orientation (001) and (200). (author)

  9. Characteristics and photocatalytic activity of TiO2 thin film sensitized with a porphyrin dye.

    Yao, K S; Wang, D Y; Chang, C Y; Ho, W Y; Yang, L Y

    2008-05-01

    In this study, a novel porphyrin dye, 5, 10, 15, 20-tetraphenyl-21H, 23H-porphine nickel (TPPN) doped TiO2 (TiO2/TPPN) thin film with visible light respondency was prepared using a sol-gel method and characterized with XRD, SEM, UV-Vis instruments. The observation showed that the absorption edge of TPPN dye-doped thin film shifted into the visible light region. The photocatalytic indigo carmine degradation results showed that under visible light irradiation (lambda > 400 nm) for 6 hrs, the photocatalytic activity of TiO2 thin film sensitized with 200 microM of TPPN dye showed the best performance, with an indigo degradation ratio up to 96%. Moreover, the TiO2/TPPN thin film showed a relevant photocatalytic bactericidal effect on Erwinia carotovora subsp. carotovora 7 induced vegetable soft rot disease in the visible spectral region. Evidence for the photocatalytic disinfection technique against a plant pathogen under visible light irradiation will have potential for direct application in future control of plant diseases in irrigation water systems. PMID:18572711

  10. Optical Spectra of Graded Nanostructured TiO2 Chiral Thin Films

    Babaei, F; Savaloni, H; 10.1016/j.optcom.2010.03.005

    2010-01-01

    The rigorous coupled wave analysis method (RCWA) is applied to the graded chiral TiO2 thin films in axial and non-axial excited states using the Bruggeman homogenization formalism. The dependence of the filtering frequency and polarization selectivity as a function of different structural parameters, are investigated. A good agreement with experimental results reported by other researchers is achieved.

  11. Structural, optical and electrochemical properties of TiO2 thin films grown by APCVD method

    Atmospheric pressure chemical vapor deposition (APCVD) of TiO2 thin films has been achieved onto glass and onto ITO-coated glass substrates, from the reaction of TiCl4 with ethyl acetate (EtOAc). The effect of the synthesis temperature on the optical, structural and electrochemical properties was studied through spectral transmittance, X-ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS) measurements. It was established that the TiO2 films deposited onto glass substrate, at temperatures greater than 400 deg. C grown with rutile type tetragonal structure, whereas the TiO2 films deposited onto ITO-coated glass substrate grown with anatase type structure. EIS was applied as suitable method to determine the charge transfer resistance in the electrolyte/TiO2 interface, typically found in dye-sensitized solar cells.

  12. Nanocrystalline TiO2 thin film electrodes prepared by common pressure hydrothermal method at low temperature

    LI Chengyu; LIN Yuan; LI Xueping; WANG Zhengping; MA Yutao; ZHOU Xiaowen; FENG Shujing; XIAO Xurui

    2005-01-01

    Nanocrystalline TiO2 thin film electrodes have been prepared from mixed pastes of tetrabutyl titanate and nanocrystalline TiO2 particles by common pressure hydrothermal method at low temperature. The tetrabutyl titanate was hydrolyzed and crystallized into anatase TiO2 to interconnect nanocrystalline TiO2 particles and adhere them to conductive substrates, obtaining highly porous and mechanically stable TiO2 nanocrystalline film. The conversion efficiencies of the dye-sensitized solar cells based on prepared electrodes on conductive glass substrates and flexible substrates were 4.8% and 1.9% under illumination of 100 mW/cm2, respectively.

  13. Synthesis of photosensitive nanograined TiO2 thin films by SILAR method

    Nanocrystalline TiO2 thin films are deposited by simple successive ionic layer adsorption and reaction (SILAR) method on glass and fluorine-doped tin oxide (FTO)-coated glass substrate from aqueous solution. The as-deposited films are heat treated at 673 K for 2 h in air. The change in structural, morphological and optical properties are studied by means of X-ray diffraction (XRD), selected area electron diffraction (SAED), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), transmission electron microscopy (TEM) and UV-vis-NIR spectrophotometer. The results show that the SILAR method allows the formation of anatase, nanocrystalline, and porous TiO2 thin films. The heat-treated film showed conversion efficiency of 0.047% in photoelectrochemical cell with 1 M NaOH electrolyte.

  14. TiO2 thin film based transparent flexible resistive switching random access memory

    Pham, Kim Ngoc; Dung Hoang, Van; Tran, Cao Vinh; Thang Phan, Bach

    2016-03-01

    In our work we have fabricated TiO2 based resistive switching devices both on transparent substrates (ITO, IGZO/glass) and transparent flexible substrate (ITO/PET). All devices demonstrate the reproducibility of forming free bipolar resistive switching with high transparency in the visible light range (∼80% at the wavelength of 550 nm). Particularly, transparent and flexible device exhibits stable resistive switching performance at the initial state (flat) and even after bending state up to 500 times with curvature radius of 10% compared to flat state. The achieved characteristics of resistive switching of TiO2 thin films seem to be promising for transparent flexible random access memory.

  15. RBS analysis of substoichiometric TiO2-anatase thin films for visible-light photocatalysis

    The anatase phase of TiO2 is the most promising photocatalyst for organic pollutants degradation. However, due to the large anatase band gap energy the possibility of using visible sunlight as energy source for the photocalatysis activation is ruled out and ultraviolet (UV) radiation with a wave length below the critical limit is thus required. Inducing defects in the anatase crystalline structure in the form of oxygen substoichiometry may theoretically reduce this large band gap energy. This paper focuses on the determination of the stoichiometry of TiO2 thin films and its influence on the photodegradation properties

  16. Low Loss Sol-Gel TiO2 Thin Films for Waveguiding Applications

    Alexis Fischer

    2013-03-01

    Full Text Available TiO2 thin films were synthesized by sol-gel process: titanium tetraisopropoxide (TTIP was dissolved in isopropanol, and then hydrolyzed by adding a water/isopropanol mixture with a controlled hydrolysis ratio. The as prepared sol was deposited by “dip-coating” on a glass substrate with a controlled withdrawal speed. The obtained films were annealed at 350 and 500 °C (2 h. The morphological properties of the prepared films were analyzed by Scanning Electron Microscopy (SEM and Atomic Force Microscopy (AFM. The optical waveguiding properties of TiO2 films were investigated for both annealing temperature using m-lines spectroscopy. The refractive indices and the film thickness were determined from the measured effective indices. The results show that the synthesized planar waveguides are multimodes and demonstrate low propagation losses of 0.5 and 0.8 dB/cm for annealing temperature 350 and 500 °C, respectively.

  17. Nano porous Al2O3-TiO2 thin film based humidity sensor prepared by spray pyrolysis technique

    Chandrashekara, H. D.; Angadi, Basavaraj; Ravikiran, Y. T.; Poornima, P.; Shashidhar, R.; Murthy, L. C. S.

    2016-05-01

    The nano porous surface structured TiO2 and Al2O3-TiO2 thin films were prepared using spray pyrolysis technique at 350°C. The XRD pattern of Al2O3-TiO2 film shows anatase phase and mixed phase of Al2TiO5. The surface morphology of films show a uniformly distributed nano porous structure. The elemental analysis through EDAX shows good stoichiometry. The sensitivity for humidity sensing were determined for both films of TiO2 and Al2O3-TiO2 and corresponding values are found to be 74.2% and 84.02%, this result reveal that Al2O3-TiO2 films shows higher sensing percent than the TiO2 due to the nano porous surface nature. The Al2O3-TiO2 film shows fast response time and long recovery time than the TiO2 film, this may be due to the meso-porous morphology of these films.

  18. Micro-porous TiO2 thin films grown on surface of Ti substrate

    WU Xiao-hong; QIN Wei; JIANG Zhao-hua; HU Xin-guo; Li Qing-fen

    2004-01-01

    Microporous titanium dioxide thin films have been grown on titanium plates by the micro-plasma oxidation method with different current densities (4, 6, 10 and 14 A/dm2). X-ray diffraction, scanning electronic microscopy and UV-Vis spectrophotometry were used to characterize the films. It is found that the films grown are microporous and consist of crystalline titanium dioxide. The micropore size and the content of anatase and rutile TiO2 phase increase with the applied voltage. The relatively higher degradation efficiency for rhodamine B is obtained in the film produced with a current density of 10 A/dm2.

  19. Photoelectrocatalytic Degradation of Sodium Oxalate by TiO2/Ti Thin Film Electrode

    Chen-Yu Chang

    2012-01-01

    Full Text Available The photocatalytically active TiO2 thin film was deposited on the titanium substrate plate by chemical vapor deposition (CVD method, and the photoelectrocatalytic degradation of sodium oxalate was investigated by TiO2 thin film reactor prepared in this study with additional electric potential at 365 nm irradiation. The batch system was chosen in this experiment, and the controlled parameters were pH, different supporting electrolytes, applied additional potential, and different electrolyte solutions that were examined and discussed. The experimental results revealed that the additional applied potential in photocatalytic reaction could prohibit recombination of electron/hole pairs, but the photoelectrocatalytic effect was decreased when the applied electric potential was over 0.25 V. Among the electrolyte solutions added, sodium sulfate improved the photoelectrocatalytic effect most significantly. At last, the better photoelectrocatalytic degradation of sodium oxalate occurred at pH 3 when comparing the pH influence.

  20. Bimodal nanostructured TiO2 thin films for dye sensitized solar cells

    Zukalová, Markéta; Kavan, Ladislav; Zukal, Arnošt; Graetzel, M.

    Málaga: BrownWalker Press, 2012. s. 99-99. ISBN 978-1-61233-558-2. [EMR 2012 : The Energy and Materials Research Conference. 20.06.2012-22.06.2012, Torremolinos] R&D Projects: GA ČR(CZ) GAP108/12/0814 Institutional support: RVO:61388955 Keywords : TiO2 * thin films * dye-sensitized solar cell Subject RIV: CG - Electrochemistry

  1. S180 cell growth on low ion energy plasma treated TiO2 thin films

    X-ray photoelectron spectroscopy (XPS) was used to characterise the effects of low energy (2 thin films deposited by radio frequency (RF) magnetron sputter system. The low energy argon ion plasma surface modification of TiO2 in a two-stage hybrid system had increased the proportion of surface states of TiO2 as Ti3+. The proportion of carbon atoms as alcohol/ether (C-OX) was decreased with increase the RF power and carbon atoms as carbonyl (C=O) functionality had increased for low RF power treatment. The proportion of C(=O)OX functionality at the surface was decreased at low power and further increase in power has showed an increase in its relive proportion at the surface. The growth of S180 cells was observed and it seems that cells are uniformly spreads on tissue culture polystyrene surface and untreated TiO2 surfaces whereas small-localised cell free area can be seen on plasma treated TiO2 surfaces which may be due to decrease in C(=O)OX, increase in C=O and active sites at the surface. A relatively large variation in the surface functionalities with no change in the surface roughness was achieved by different RF plasma treatments of TiO2 surface whereas no significant change in S180 cell growth with different plasma treatments. This may be because cell growth on TiO2 was mainly influenced by nano-surface characteristics of oxide films rather than surface chemistry

  2. Low Loss Sol-Gel TiO2 Thin Films for Waveguiding Applications

    Alexis Fischer; Ovidiu Brinza; Iva Ninova-Kuznetsova; Dominique Vrel; Tahar Touam; Lamia Znaidi; Azzedine Boudrioua

    2013-01-01

    TiO2 thin films were synthesized by sol-gel process: titanium tetraisopropoxide (TTIP) was dissolved in isopropanol, and then hydrolyzed by adding a water/isopropanol mixture with a controlled hydrolysis ratio. The as prepared sol was deposited by “dip-coating” on a glass substrate with a controlled withdrawal speed. The obtained films were annealed at 350 and 500 °C (2 h). The morphological properties of the prepared films were analyzed by Scanning Electron Microscopy (SEM) and Atomic Force ...

  3. Fe ion-implanted TiO2 thin film for efficient visible-light photocatalysis

    Impellizzeri, G.; Scuderi, V.; Romano, L.; Sberna, P. M.; Arcadipane, E.; Sanz, R.; Scuderi, M.; Nicotra, G.; Bayle, M.; Carles, R.; Simone, F.; Privitera, V.

    2014-11-01

    This work shows the application of metal ion-implantation to realize an efficient second-generation TiO2 photocatalyst. High fluence Fe+ ions were implanted into thin TiO2 films and subsequently annealed up to 550 °C. The ion-implantation process modified the TiO2 pure film, locally lowering its band-gap energy from 3.2 eV to 1.6-1.9 eV, making the material sensitive to visible light. The measured optical band-gap of 1.6-1.9 eV was associated with the presence of effective energy levels in the energy band structure of the titanium dioxide, due to implantation-induced defects. An accurate structural characterization was performed by Rutherford backscattering spectrometry, transmission electron microscopy, Raman spectroscopy, X-ray diffraction, and UV/VIS spectroscopy. The synthesized materials revealed a remarkable photocatalytic efficiency in the degradation of organic compounds in water under visible light irradiation, without the help of any thermal treatments. The photocatalytic activity has been correlated with the amount of defects induced by the ion-implantation process, clarifying the operative physical mechanism. These results can be fruitfully applied for environmental applications of TiO2.

  4. Preparation of titanium dioxide porous thin films via photopolymerization of the colloidal TiO2 dispersion

    Titanium dioxide (TiO2) thin films with porous structures have been successfully achieved by photopolymerization stimulating the particle dispersion combined TiO2 colloid with photoinitiator and monomer. The photopolymerization monomer Pentaerythritol Triacrylate (PETA) and photoinitiator 2-Hydroxy-2-methyl-propiophenone (HMPP) are added to the TiO2 colloidal solution to form the new colloidal TiO2 dispersion. After coating the dispersion on the substrate, the coating is cured with UV light. With the evaporation of solvent and the formation of microgels induced by polymerization, a phase separation occurs in the system. A porous TiO2 film with various pore sizes from mesoporous to macroporous could be produced after heat treatment. The morphology and size of pores could be tuned by changing the process of phase separation, which is controlled by the composition of colloidal TiO2 dispersion. The content of photoinitiator and the temperature of heat treatment were decided by UV–vis absorption spectra and thermal analysis (DTA–TGA), respectively; Real-Time Fourier-transform infrared (RT-FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffractometer (XRD) and high-resolution transmission electron microscopy (HR-TEM) were used to characterize the TiO2 films. The as-prepared TiO2 porous films exhibited higher photocatalytic activity for degradation methylene blue in comparison with conventional TiO2 dense film due to its porous structure. - Highlights: • TiO2 porous film was prepared by photopolymerization stimulating particle dispersion. • Colloidal TiO2 dispersion contained photoinitiator and monomer for curing reaction. • The morphology and size of pores were dependent on the composition of dispersion. • The phase separation mechanism occurred during the photopolymerization was proposed. • TiO2 porous films showed high photocatalytic activity

  5. Study on fabrication of TiO2 thin films by spin - coating and their optical properties

    Zharvan, Vicran; Daniyati, Risqa; Nur Ichzan A., S.; Yudoyono, Gatut; Darminto

    2016-03-01

    Study on fabrication of TiO2 thin films and their optical properties in UV-VIS spectrum has been conducted. TiO2 nanopowders were prepared by co-precipitation method with varying mixing duration for 5, 10 and 25 hours using TiCl3 as precursor. The as-synthesized TiO2 phase is anatase having crystalline size of 14.25 nm, 13.75 nm and 12.62, respectively for the corresponding mixing duration. Thin films of TiO2 were fabricated by spin coating method and then checked by XRD diffractometer and UV-Vis Spectrophotometer to examine their structure and band gap energy. The prepared films also contain anatase phase of TiO2 with respective band gap of 3.70 eV, 3.74 eV and 3.76 eV, depending on the powders and their treatment.

  6. Thin Functional Films of TiO2 Nanoparticles

    Morozová, Magdalena; Klusoň, Petr; Hejda, S.; Kment, Štěpán; Šolcová, Olga

    Praha : J.Heyrovský Institute of Physical Chemistry, v. v. i, 2011 - (Mansfeldová, V.; Tarábková, H.), s. 56 ISBN 978-80-87351-17-8. [Heyrovský Discussion - Nanostructures on Electrodes /44./. Třešť (CZ), 26.06.2011-30.06.2011] R&D Projects: GA ČR GD203/08/H032; GA AV ČR KAN400720701 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z10100522 Keywords : spectroscopy * films * nanoparticles Subject RIV: CF - Physical ; Theoretical Chemistry

  7. Controlled formation of anatase and rutile TiO2 thin films by reactive magnetron sputtering

    Damon Rafieian

    2015-09-01

    Full Text Available We discuss the formation of TiO2 thin films via DC reactive magnetron sputtering. The oxygen concentration during sputtering proved to be a crucial parameter with respect to the final film structure and properties. The initial deposition provided amorphous films that crystallise upon annealing to anatase or rutile, depending on the initial sputtering conditions. Substoichiometric films (TiOx<2, obtained by sputtering at relatively low oxygen concentration, formed rutile upon annealing in air, whereas stoichiometric films formed anatase. This route therefore presents a formation route for rutile films via lower (<500 °C temperature pathways. The dynamics of the annealing process were followed by in situ ellipsometry, showing the optical properties transformation. The final crystal structures were identified by XRD. The anatase film obtained by this deposition method displayed high carriers mobility as measured by time-resolved microwave conductance. This also confirms the high photocatalytic activity of the anatase films.

  8. Preparation of TiO2-based nanotubes/nanoparticles composite thin film electrodes for their electron transport properties

    The composite thin film electrodes were prepared with one-dimensional (1D) TiO2-B nanotubes (NTs) and zero-dimensional TiO2 nanoparticles (NPs) based on different weight ratios. The electron transport properties of the NTs/NPs composite thin film electrodes applied for dye-sensitized solar cells had been investigated systematically. The results indicated that although the amount of dye adsorption decreased slightly, the devices with the NTs/NPs composite thin film electrodes could obtain higher open-circuit voltage and overall conversion efficiency compared to devices with pure TiO2 NPs electrodes by rational tuning the weight ratio of TiO2-B NTs and TiO2 NPs. When the weight ratio of TiO2-B NTs in the NTs/NPs composite thin film electrodes increased, the density of states and recombination rate decreased. The 1D structure of TiO2-B NTs can provide direct paths for electron transport, resulting in higher electron lifetime, electron diffusion coefficient and electron diffusion length. The composite thin film electrodes possess the merits of the rapid electron transport of TiO2-B NTs and the high surface area of TiO2 NPs, which has great applied potential in the field of photovoltaic devices. - Highlights: • The composite thin film electrodes (CTFEs) were prepared with nanotubes and nanoparticles. • The CTFEs possess the rapid electron transport and high surface area. • The CTFEs exhibit lower recombination rate and longer electron life time. • The CTFEs have great applied potential in the field of photovoltaic devices

  9. Flame-Made Pt-Loaded TiO2 Thin Films and Their Application as H2 Gas Sensors

    Weerasak Chomkitichai

    2013-01-01

    Full Text Available The hydrogen gas sensors were developed successfully using flame-made platinum-loaded titanium dioxide (Pt-loaded TiO2 nanoparticles as the sensing materials. Pt-loaded TiO2 thin films were prepared by spin-coating technique onto Al2O3 substrates interdigitated with Au electrodes. Structural and gas-sensing characteristics were examined by using scanning electron microscopy (SEM and showed surface morphology of the deposited film. X-ray diffraction (XRD patterns can be confirmed to be the anatase and rutile phases of TiO2. High-resolution transmission electron microscopy (HRTEM showed that Pt nanoparticles deposited on larger TiO2 nanoparticles. TiO2 films loaded with Pt nanoparticles were used as conductometric sensors for the detection of H2. The gas sensing of H2 was studied at the operating temperatures of 300, 350, and 400°C in dry air. It was found that 2.00 mol% Pt-loaded TiO2 sensing films showed higher response towards H2 gas than the unloaded film. In addition, the responses of Pt-loaded TiO2 films at all operating temperatures were higher than that of unloaded TiO2 film. The response increased and the response time decreased with increasing of H2 concentrations.

  10. Random lasing at the edge of a TiO2 nanotube thin film.

    Zhu, Shu; Shen, Zhenhua; Jiang, Bei; Chen, Xianfeng

    2016-07-01

    In this paper, we introduce a random laser in which lasing action is observed at the edge of a dye-doped TiO2 thin film. A TiO2 nanotube membrane serves as a disordered structure that enhances the optical multiple scattering effect, while Rhodamine 6G dissolved in ethylene glycol is used as a gain medium. In the experiment, a random laser with a low threshold is observed when optically pumped at the fringe of a TiO2 nanotube membrane, which makes it practical for microfluidic integration. Simulation results show that multiple scattered light between the nanotubes and ethylene glycol solution is more likely to form a resonance loop with the help of a random edge structure. This well interrupted the appearance of coherent spikes in the emission laser spectrum in the experiment. The edge random laser offers simplicity and convenience in both fabrication and operation, which makes it a promising component for optofluidic laser integration with TiO2 functional material. PMID:27409195

  11. A short literature survey on iron and cobalt ion doped TiO2 thin films and photocatalytic activity of these films against fungi

    Highlights: ► Co or Fe doped TiO2 thin films were prepared by sol–gel method. ► We obtained lower Eg values for Fe-doped and Co-TiO2 thin films. ► Doping greatly affected the size and shape of the TiO2 nanoparticles. ► Photocatalytic killing effect of the doped TiO2 thin films on C. albicans and A. niger was significantly higher than undoped TiO2 thin film for short exposure periods. - Abstract: In this study, a short recent literature survey which concentrated on the usage of Fe3+ or Co2+ ion doped TiO2 thin films and suspensions were summarized. Additionally, a sol–gel method was used for preparation of the 2% Co or Fe doped TiO2 thin films. The surface of the prepared materials was characterised using scanning-electron microscopy (SEM) combined with energy dispersive X-ray (EDX) analysis and band gap of the films were calculated from the transmission measurements that were taken over the range of 190 and 1100 nm. The Eg value was 3.40 eV for the pure TiO2, 3.00 eV for the Fe-doped TiO2 film and 3.25 eV for Co-TiO2 thin film. Iron or cobalt doping at lower concentration produce more uniformed particles and doping greatly affected the size and shape of the TiO2 nanoparticles. Photocatalytic killing effect of the 2% Co doped TiO2 thin film on Candida albicans was significantly higher than Fe doped TiO2 thin film for short and long exposure periods. Doped thin films were more effective on Aspergillus niger for short exposure periods.

  12. Tio2 Nanoparticles Coated With Porphyrin Dye Thin Film As Fluorescence Gas Sensor

    This research explores the possibility of using fluorescence technique to detect the presence of volatile organic compounds based on a single sensing material. The material used was TiO2 nanoparticles coated with porphyrin dye. The TiO2 nanoparticles colloid is in a sol-gel form synthesized from titanium (IV) ethoxide in ethanol with addition of potassium chloride (KCl) as stabilizer. TiO2 nanoparticles were then coated with porphyrin dye, Manganese (III) 5,10,15,20 tetra (4-pyridyl)-21H, 23H porphine chloride tetrakis (meta chloride). The coated nanoparticles were deposited on quartz substrate using self-assembly through dip coating technique. The sensing properties of the thin film toward volatile organic compounds; ethanol, acetone, cyclohexane and 2-propanol were studied using luminescence spectrometer. It was found that the thin film produced different emission spectra peaks for different volatile organic compounds (VOCs). Hence, it eases chemical identification process and potentially be use as fluorescence gas sensor. (author)

  13. Basella alba rubra spinach pigment-sensitized TiO2 thin film-based solar cells

    Gokilamani, N.; Muthukumarasamy, N.; Thambidurai, M.; Ranjitha, A.; Velauthapillai, Dhayalan

    2015-03-01

    Nanocrystalline TiO2 thin films have been prepared by sol-gel dip coating method. The X-ray diffraction results showed that TiO2 thin films annealed at 400, 450 and 500 °C are of anatase phase and the peak corresponding to the (101) plane is present in all the samples. The grain size of TiO2 thin films was found to increase with increasing annealing temperature. The grain size is found to be 20, 25 and 33 nm for the films annealed at 400, 450 and 500 °C. The structure of the TiO2 nanocrystalline thin films have been examined by high-resolution transmission electron microscope, Raman spectroscopy and FTIR spectroscopy. TiO2 thin films were sensitized by natural dyes extracted from basella alba rubra spinach. It was found that the absorption peak of basella alba rubra extract is at about 665 nm. The dye-sensitized TiO2-based solar cell sensitized using basella alba rubra exhibited a J sc of 4.35 mA cm-2, V oc of 0.48 V, FF of 0.35 and efficiency of 0.70 %. Natural dyes as sensitizers for dye-sensitized solar cells are promising because of their environmental friendliness, low-cost production and fully biodegradable.

  14. Highly Crystalline Nanoparticle Suspensions for Low-Temperature Processing of TiO2 Thin Films.

    Watté, Jonathan; Lommens, Petra; Pollefeyt, Glenn; Meire, Mieke; De Buysser, Klaartje; Van Driessche, Isabel

    2016-05-25

    In this work, we present preparation and stabilization methods for highly crystalline TiO2 nanoparticle suspensions for the successful deposition of transparent, photocatalytically active TiO2 thin films toward the degradation of organic pollutants by a low temperature deposition method. A proof-of-concept is provided wherein stable, aqueous TiO2 suspensions are deposited on glass substrates. Even if the processing temperature is lowered to 150-200 °C, the subsequent heat treatment provides transparent and photocatalytically active titania thin layers. Because all precursor solutions are water-based, this method provides an energy-efficient, sustainable, and environmentally friendly synthesis route. The high load in crystalline titania particles obtained after microwave heating opens up the possibility to produce thin coatings by low temperature processing, as a conventional crystallization procedure is in this case superfluous. The impact of the precursor chemistry in Ti(4+)-peroxo solutions, containing imino-diacetic acid as a complexing ligand and different bases to promote complexation was studied as a function of pH, reaction time and temperature. The nanocrystal formation was followed in terms of colloidal stability, crystallinity and particle size. Combined data from Raman and infrared spectroscopy, confirmed that stable titanium precursors could be obtained at pH levels ranging from 2 to 11. A maximum amount of 50.7% crystallinity was achieved, which is one of the highest reported amounts of anatase nanoparticles that are suspendable in stable aqueous titania suspensions. Decoloring of methylene blue solutions by precipitated nanosized powders from the TiO2 suspensions proves their photocatalytic properties toward degradation of organic materials, a key requisite for further processing. This synthesis method proves that the deposition of highly crystalline anatase suspensions is a valid route for the production of photocatalytically active, transparent

  15. Hydrogen irradiation on TiO2 nano-thin films

    Heidari, Sh.; Mohammadizadeh, M. R.; Mahjour-Shafiei, M.; Larijani, M. M.; Malek, M.

    2015-10-01

    Titanium dioxide thin films were coated on soda-lime glass substrates using spray pyrolysis method with a thickness of 152 ± 10 nm. The films were irradiated with hydrogen ions at room temperature at various beam energies and fluences. Optimized incident beam energy and beam fluence were obtained to improve photocatalytic and hydrophilicity properties of TiO2 thin films by narrowing the band gap. Samples were characterized by scanning electron microscopy to study the surface morphology and by UV-Vis absorption spectroscopy to measure the band gap. The optical band gap of H-doped anatase TiO2 thin films irradiated with hydrogen beam with energies of 2 and 4 keV and a fluence of 1015 ions/cm2 was narrowed from 3.34 eV (before irradiation) to 3.04 and 2.92 eV (after irradiation), respectively. The irradiated sample with energy of 4 keV with a fluence of 1015 ions/cm2 has the best improvement. This is attributed to the contraction of the band gap and to the increase in surface active site. Furthermore, it was observed that photocatalytic and hydrophilicity properties of this sample were improved, as well.

  16. TiO2 thin film growth using the MOCVD method

    Bernardi M.I.B.

    2001-01-01

    Full Text Available Titanium oxide (TiO2 thin films were obtained using the MOCVD method. In this report we discuss the properties of a film, produced using a ordinary deposition apparatus, as a function of the deposition time, with constant deposition temperature (90 °C, oxygen flow (7,0 L/min and substrate temperature (400 °C. The films were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, atomic force microscopy (AFM and visible and ultra-violet region spectroscopy (UV-Vis. The films deposited on Si (100 substrates showed the anatase polycrystalline phase, while the films grown on glass substrates showed no crystallinity. Film thickness increased with deposition time as expected, while the transmittance varied from 72 to 91% and the refractive index remained close to 2.6.

  17. Preparation of TiO2 thin films from autoclaved sol containing needle-like anatase crystals

    A new inorganic sol-gel method was introduced in this paper to prepare TiO2 thin films. The autoclaved sol with needle-like anatase crystals was synthesized using titanyl sulfate (TiOSO4) and peroxide (H2O2) as starting materials. The transparent anatase TiO2 thin films were prepared on glass slides from the autoclaved sol by sol-gel dip-coating method. A wide range of techniques such as Fourier transform infrared transmission spectra (FT-IR), X-ray diffraction (XRD), thermogravimetry-differential thermal analysis (TG-DTA), scanning electron microscopes, X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible spectrum were applied to characterize the autoclaved sol and TiO2 thin films. The results indicate that the autoclaved sol is flavescent, semitransparent and stable at room temperature. The anatase crystals of TiO2 films connect together to form net-like structure after calcined and the films become uniform with increasing heating temperature. The surface of the TiO2 films contain not only Ti and O elements, but also a small amount of N and Na elements diffused from substrates during heat treatment. The TiO2 films are transparent and their maximal light transmittances exceed 80% under visible light region

  18. Gas sensing properties of very thin TiO2 films prepared by atomic layer deposition (ALD)

    Very thin titanium dioxide (TiO2) films of less than 10 nm were deposited by atomic layer deposition (ALD) in order to study their gas sensing properties. Applying the quartz crystal microbalance (QCM) method, prototype structures with the TiO2 ALD deposited thin films were tested for sensitivity to NO2. Although being very thin, the films were sensitive at room temperature and could register low concentrations as 50-100 ppm. The sorption is fully reversible and the films seem to be capable to detect for long term. These initial results for very thin ALD deposited TiO2 films give a promising approach for producing gas sensors working at room temperature on a fast, simple and cost-effective technology

  19. Growth of TiO2 Thin Film on Various Substrates using RF Magnetron Sputtering

    The conductivity of Titanium Dioxide (TiO2) thin film fabricated using Radio Frequency (RF) Magnetron Sputtering on Silicon (Si), Indium doped--Tin Oxide (ITO) and microscope glass (M) substrates is presented in this paper. The dependant of thin film thickness and type of substrate been discussed. TiO2 was deposited using Ti target in Ar+O2(45:10) mixture at 250 W for 45, 60, 75, 90, 105 and 120 minute. Resultant thickness varies from 295 nm to 724 nm with deposition rate 6.4 nm/min. On the other hand, resistivity, Rs value for ITO substrate is between 5.72x10-7 to 1.54x10-6Ω.m, Si substrate range is between 3.52x10-6 to 1.76x10-5Ω.m and M substrate range is between 99 to 332 Ω.m. The value of resistivity increases with the thickness of the thin film.

  20. Preparation and Characterization of TiO2-SiO2 Thin Films

    Sol-gel, is a method being used for preperation of thin films for a very long time. Its easy application process with easily available equipments that are used and the low process temperatures are the reasons for being utilized this much. A very common thin film type, TiO2-SiO2, that has been used in optical applications for a long time, is the basic structure involved in this research. In this work, the titania (TiO2) and the silica (SiO2) solutions which had been preperated seperately, were mixed with different ratios, and the differences between these mixtures that might had been occurred were investigated. The glass substrates, which had been cleaned with a special method were dipped into the mixed solutions with a constant speed which they had exactly the same while they were being withdrawned. After being dried in mid-air for a while, they were heated to 150 degree and then were dipped again. Once the number of the layers that was required is reached with reprocesses, the substrates were heated to 600 degree. The optical and the structural properties of the films deposited on the substrates were investigated. Some differences in optical properties of these films that were produced from different ratios of solutions were observed as result

  1. Inductive couple plasma reactive ion etching characteristics of TiO2 thin films

    Changes in the inductively coupled plasma reactive ion etching characteristics of TiO2 thin films in response to the addition of HBr, Cl2 and C2F6 to Ar gas were investigated. As the HBr, Cl2 and C2F6 concentration increased, the etch rate increased; however, the etch profile degree of anisotropy followed a different trend. As HBr concentration increased, the greatest anisotropic etch profile was obtained at 100% HBr, while the greatest anisotropic etch profile was obtained at concentrations of 25% when etching was conducted under C2F6 and Cl2. Field emission scanning electron microscopy revealed that 25% C2F6 generated the greatest vertical etch profile; hence, etch parameters were varied at this concentration. The effects of rf power, dc-bias voltage and gas pressure on the etch rate and etch profile were also investigated. The etch rate and degree of anisotropy in the etch profile increased with increasing rf power and dc-bias voltage and decreasing gas pressure. X-ray photoelectron spectroscopy analysis of the films etched under a C2F6/Ar gas mixture revealed the existence of etch byproducts containing F (i.e. TiFx) over the film. CxFy compounds were not detected on the film surface, probably due to contamination with atmospheric carbon. - Highlights: • Reactive ion etching of TiO2 films under HBr, C2F6, and Cl2 gases was studied. • Etch rate and etch profile of TiO2 films were investigated under each gas chemistry. • The highest degree of anisotropy was achieved at 25% C2F6/Ar. • Strong etch conditions at 25% C2F6/Ar increased etch rate and degree of anisotropy. • X-ray photoelectron spectroscopy revealed the existence of F-containing etch residues

  2. Fabrication and evaluation of TiO2/graphite silica bilayer thin films prepared by laser ablation method

    The bilayer thin film composed of graphite silica (GS) and TiO2 was prepared by the laser ablation technique. The properties of the thin films considerably depended on the laser ablation conditions such as gas pressure and substrate temperature in a chamber. The laser ablation of GS caused complete disappearance of the quartz XRD (X-ray diffraction) peaks in GS. The GS loading, especially at a thickness of around 200 nm, led to significant enhancement in the photocatalytic activity of the TiO2 thin film for the hydrogen production and the methylene blue decomposition in spite of the destruction of the quartz crystal in GS

  3. Nano-morphology of lithiated thin film TiO2 anatase probed with in situ neutron reflectometry

    In situ neutron reflectometry reveals the intercalation scheme of lithiated thin film TiO2 anatase in terms of phase boundary movement. The Li-rich lithium titanate phase progressively moves inside the TiO2 anatase electrode as a front parallel to the interface. In contrast to previous suggestions for this system, the phase front moves back during lithium extraction exactly in the way it came in. The electrochemical side reactions result in a ∼5.5 nm-thick film on top of the TiO2 electrode extending into the organic electrolyte which is believed to passivate the Li-intercalation

  4. Phase determination of filtered vacuum arc deposited TiO2 thin films by optical modeling

    Thin films of TiO2 were produced using filtered vacuum arc deposition. Arc currents were 275, 300, 325 A, and the oxygen pressure during deposition was 0.93 Pa. The substrates were glass microscope slides, at temperatures of 25 oC (RT), 200 oC, and 400 oC. Film thickness was in the range 100 to 250 nm, depending on the deposition conditions. Film structure and chemical composition were determined using XRD and XPS analyses, respectively. As-deposited films were amorphous, except to two samples that were found to be crystalline (deposited with 300 A, 325 A at 400 oC), and the crystalline phase was close to that of anatase. All of the films were partially crystallized by annealing in air at 450 oC for 1 h. The O:Ti atomic concentration ratio was in the range 1.6:1-2:1, independent of deposition conditions. The optical parameters, refractive index and the extinction coefficient of the films were determined using variable angle spectroscopic ellipsometry. In addition, the optical transmission of the films were determined in the UV-VIS and IR regions. The average optical transmission in the VIS spectrum was 70-85%, affected by the interference in the film with 90% maxima and 60% minima. The refractive index at λ = 550 nm was in the range 2.4 to 2.7, depending on the deposition conditions and annealing. Using the semi-empirical model of Wemple and DiDomenico for the dielectric function below the interband absorption edge of ionic and covalent solids, the dispersion energy parameters of TiO2 (Eo, Ed) were calculated. The underlying structural order of the amorphous films was inferred by comparing the dispersion energy parameters of the amorphous films with those of crystalline TiO2. As expected, the refractive index of the amorphous films depended on the underlying phase of the film. The optical analyses indicated that the underlying phase of the amorphous films deposited on RT substrates was close to anatase, whereas the underlying phase of the amorphous films deposited

  5. TiO 2 Thin Films Prepared via Adsorptive Self-Assembly for Self-Cleaning Applications

    Xi, Baojuan

    2012-02-22

    Low-cost controllable solution-based processes for preparation of titanium oxide (TiO 2) thin films are highly desirable, because of many important applications of this oxide in catalytic decomposition of volatile organic compounds, advanced oxidation processes for wastewater and bactericidal treatments, self-cleaning window glass for green intelligent buildings, dye-sensitized solar cells, solid-state semiconductor metal-oxide solar cells, self-cleaning glass for photovoltaic devices, and general heterogeneous photocatalysis for fine chemicals etc. In this work, we develop a solution-based adsorptive self-assembly approach to fabricate anatase TiO 2 thin films on different glass substrates such as simple plane glass and patterned glass at variable compositions (normal soda lime glass or solar-grade borofloat glass). By tuning the number of process cycles (i.e., adsorption-then-heating) of TiO 2 colloidal suspension, we could facilely prepare large-area TiO 2 films at a desired thickness and with uniform crystallite morphology. Moreover, our as-prepared nanostructured TiO 2 thin films on glass substrates do not cause deterioration in optical transmission of glass; instead, they improve optical performance of commercial solar cells over a wide range of incident angles of light. Our as-prepared anatase TiO 2 thin films also display superhydrophilicity and excellent photocatalytic activity for self-cleaning application. For example, our investigation of photocatalytic degradation of methyl orange indicates that these thin films are indeed highly effective, in comparison to other commercial TiO 2 thin films under identical testing conditions. © 2012 American Chemical Society.

  6. TiO2 thin films prepared via adsorptive self-assembly for self-cleaning applications.

    Xi, Baojuan; Verma, Lalit Kumar; Li, Jing; Bhatia, Charanjit Singh; Danner, Aaron James; Yang, Hyunsoo; Zeng, Hua Chun

    2012-02-01

    Low-cost controllable solution-based processes for preparation of titanium oxide (TiO(2)) thin films are highly desirable, because of many important applications of this oxide in catalytic decomposition of volatile organic compounds, advanced oxidation processes for wastewater and bactericidal treatments, self-cleaning window glass for green intelligent buildings, dye-sensitized solar cells, solid-state semiconductor metal-oxide solar cells, self-cleaning glass for photovoltaic devices, and general heterogeneous photocatalysis for fine chemicals etc. In this work, we develop a solution-based adsorptive self-assembly approach to fabricate anatase TiO(2) thin films on different glass substrates such as simple plane glass and patterned glass at variable compositions (normal soda lime glass or solar-grade borofloat glass). By tuning the number of process cycles (i.e., adsorption-then-heating) of TiO(2) colloidal suspension, we could facilely prepare large-area TiO(2) films at a desired thickness and with uniform crystallite morphology. Moreover, our as-prepared nanostructured TiO(2) thin films on glass substrates do not cause deterioration in optical transmission of glass; instead, they improve optical performance of commercial solar cells over a wide range of incident angles of light. Our as-prepared anatase TiO(2) thin films also display superhydrophilicity and excellent photocatalytic activity for self-cleaning application. For example, our investigation of photocatalytic degradation of methyl orange indicates that these thin films are indeed highly effective, in comparison to other commercial TiO(2) thin films under identical testing conditions. PMID:22260264

  7. Effects of Ni doping on photocatalytic activity of TiO2 thin films prepared by liquid phase deposition technique

    Noor Shahina Begum; H M Farveez Ahmed; K R Gunashekar

    2008-10-01

    The TiO2 thin films doped by Ni uniformly and non-uniformly were prepared on glass substrate from an aqueous solution of ammonium hexa-fluoro titanate and NiF2 by liquid phase deposition technique. The addition of boric acid as an – scavenger will shift the equilibrium to one side and thereby deposition of the film is progressed. The rate of the reaction and the nature of deposition depend on growing time and temperature. The resultant films were characterized by XRD, EDAX, UV and SEM. The result shows that the deposited films have amorphous background, which becomes crystalline at 500°C. The EDAX data confirms the existence of Ni atoms in TiO2 matrix. XRD analysis reveals the peaks corresponding to Ni but no peak of crystalline NiO was found. The transmittance spectra of Ni uniformly and non-uniformly doped TiO2 thin films show `blue shift and red shift’, respectively. Ni-doped TiO2 thin films can be used as photocatalyst for the photodegradation of methyl orange dye. It was found that, organic dye undergoes degradation efficiently in presence of non-uniformly Ni-doped TiO2 thin films when compared to uniformly doped films and pure TiO2 films under visible light. The photocatalytic activity increases with increase in the concentration of Ni in case of nonuniformly doped thin films but decreases with the concentration when uniformly doped thin films were used.

  8. A non-labeled DNA biosensor based on light addressable potentiometric sensor modified with TiO_2 thin film

    Xiao-lin ZONG; Chun-sheng WU; Xiao-ling WU; Yun-feng LU; Ping WANG

    2009-01-01

    Titanium dioxide (TiO_2) thin film was deposited on the surface of the light addressable potentiometric sensor (LAPS) to modify the sensor surface for the non-labeled detection of DNA molecules. To evaluate the effect of ultraviolet (UV) treatment on the silanization level of TiO_2 thin film by 3-aminopropyltrietboxysilane (APTS), fluorescein isothiocyanate (FITC) was used to label the amine group on the end of APTS immobilized onto the TiO_2 thin film. We found that, with UV irradiation, the silani-zation level of the irradiated area of the TiO_2 film was improved compared with the non-irradiated area under well-controlled conditions. This result indicates that TiO_2 can act as a coating material on the biosensor surface to improve the effect and effi-ciency of the covalent immobilization of biomolecules on the sensor surface. The artificially synthesized probe DNA molecules were covalently linked onto the surface of TiO_2 film. The hybridization of probe DNA and target DNA was monitored by the recording of Ⅰ-Ⅴ curves that shift along the voltage axis during the process of reaction. A significant LAPS signal can be detected at 10 μmol/L of target DNA sample.

  9. TiO2 compact layer for dye-sensitized SnO2 nanocrystalline thin film

    A TiO2 compact layer was coated on fluorine-doped tin oxide (FTO) glass substrate prior to deposition of SnO2 nanocrystalline thin film to suppress backflow of electrons from FTO to the SnO2 nanocrystalline thin film. The resultant thin film was used as a photoelectrode to fabricate dye-sensitized solar cell. For comparison, a SnO2 compact layer was also prepared to discuss the effect of the TiO2 compact layer on the electron backflow process. Compared with the dye-sensitized SnO2 nanocrystalline thin film solar cell without the compact layer, light-to-electric conversion efficiency for the solar cell with the TiO2 compact layer was improved by 82.1% and it was even improved by 41.7% compared with the cell with the SnO2 compact layer. Electrochemical impedance spectroscopy and open-circuit voltage decay of dye-sensitized solar cells were measured to demonstrate the improvement mechanism due to the TiO2 compact layer. Both recombination resistance at the photoelectrode/electrolyte interface and lifetime of electrons on the SnO2 nanocrystalline thin film were increased due to introduction of the TiO2 compact layer. Because the conduction band of TiO2 is higher than that of SnO2, the TiO2 compact layer acts as not only a physical barrier to separate FTO substrate from electrolyte, thus suppressing recombination of electrons on FTO with the electrolyte, but also a potential barrier to effectively block the backflow of electrons from FTO substrate to the SnO2 thin film

  10. Photocatalytic Functional Coating of TiO2 Thin Film Deposited by Cyclic Plasma Chemical Vapor Deposition at Atmospheric Pressure

    Kwon, Jung-Dae; Rha, Jong-Joo; Nam, Kee-Seok; Park, Jin-Seong

    2011-08-01

    Photocatalytic TiO2 thin films were prepared with titanium tetraisopropoxide (TTIP) using cyclic plasma chemical vapor deposition (CPCVD) at atmospheric pressure. The CPCVD TiO2 films contain carbon-free impurities up to 100 °C and polycrystalline anatase phases up to 200 °C, due to the radicals and ion-bombardments. The CPCVD TiO2 films have high transparency in the visible wavelength region and absorb wavelengths below 400 nm (>3.2 eV). The photocatalytic effects of the CPCVD TiO2 and commercial sprayed TiO2 films were measured by decomposing methylene blue (MB) solution under UV irradiation. The smooth CPCVD TiO2 films showed a relatively lower photocatalytic efficiency, but superior catalyst-recycling efficiency, due to their high adhesion strength on the substrates. This CPCVD technique may provide the means to produce photocatalytic thin films with low cost and high efficiency, which would be a reasonable candidate for practical photocatalytic applications, because of the reliability and stability of their photocatalytic efficiency in a practical environment.

  11. Electrochromic TiO2, ZrO2 and TiO2-ZrO2 thin films by dip-coating method

    Sol-gel processing of TiO2, ZrO2 and mixed Ti/Zr oxide thin films has been studied as application of these coatings in electrochromic devices. Their structural transformations as a function of annealing temperatures were analyzed by XRD and FTIR techniques. Electrochromic behavior of the three kind materials was investigated by cyclic voltammetry and the basic electrochromic characteristics were determined.

  12. Photocatalytical Antibacterial Activity of Mixed-Phase TiO2 Nanocomposite Thin Films against Aggregatibacter actinomycetemcomitans

    Sinem Yeniyol

    2015-01-01

    Full Text Available Mixed-phase TiO2 nanocomposite thin films consisting of anatase and rutile prepared on commercially pure Ti sheets via the electrochemical anodization and annealing treatments were investigated in terms of their photocatalytic activity for antibacterial use around dental implants. The resulting films were characterized by scanning electron microscopy (SEM, and X-ray diffraction (XRD. The topology was assessed by White Light Optical Profiling (WLOP in the Vertical Scanning Interferometer (VSI mode. Representative height descriptive parameters of roughness Ra and Rz were calculated. The photocatalytic activity of the resulting TiO2 films was evaluated by the photodegradation of Rhodamine B (RhB dye solution. The antibacterial ability of the photocatalyst was examined by  Aggregatibacter actinomycetemcomitans suspensions in a colony-forming assay. XRD showed that anatase/rutile mixed-phase TiO2 thin films were predominantly in anatase and rutile that were 54.6 wt% and 41.9 wt%, respectively. Craters (2–5 µm and protruding hills (10–50 µm on Ti substrates were produced after electrochemical anodization with higher Ra and Rz surface roughness values. Anatase/rutile mixed-phase TiO2 thin films showed 26% photocatalytic decolorization toward RhB dye solution. The number of colonizing bacteria on anatase/rutile mixed-phase TiO2 thin films was decreased significantly in vitro. The photocatalyst was effective against A. actinomycetemcomitans colonization.

  13. OPTICAL CHARACTERIZATION OF TiO2 THIN FILM ON SILICON SUBSTRATE DEPOSITED BY DC REACTIVE MAGNETRON SPUTTERING

    H.Q. Wang; H. Shen; D.C. Ba; B.W. Wang; L.S. Wen; D. Chen

    2005-01-01

    TiO2 thin film has attracted considerable attention in recent years, due to its different refractive index and transparency with amorphous and different crystals in the visible and near-infrared wavelength region, high dielectric constant, wide band gap, high wear resistance and stability, etc, for which make it being used in many fields. This paper aims to investigate the optical characterization of thin film TiO2 on silicon wafer. The TiO2 thin films were prepared by DC reactive magnetron sputtering process from Ti target. The reflectivity of the films was measured by UV-3101PC, and the index of refraction (n) and extinction coefficient (k) were measured by n & k Analyzer 1200.

  14. Hybrid functional IrO2-TiO2 thin film resistor prepared by atomic layer deposition for thermal inkjet printheads

    Won-Sub KWACK; Hyoung-Seok MOON; Seong-Jun JEONG; Qi-min WANG; Se-Hun KWON

    2011-01-01

    IrO2-TiO2 thin films were prepared by atomic layer deposition using Ir(EtCp)(COD) and titanium isopropoxide (TTIP).in the IrO2-TiO2 thin films. The low temperature coefficient of resistance(TCR) values can be obtained by adopting IrO2-TiO2 composite thin films. Moreover, the change in the resistivity of lrO2-TiO2 thin films was below 10% even after O2 annealing process at 600 ℃. The step stress test results show that IrO2-TiO2 films have better characteristics than conventional TaN08 heater resistor.Therefore, IrO2-TiO2 composite thin films can be used as a heater resistor material in thermal inkjet printhead.

  15. Study of nanoparticles TiO2 thin films on p-type silicon substrate using different alcoholic solvents

    Muaz, A. K. M.; Hashim, U.; Arshad, M. K. Md.; Ruslinda, A. R.; Ayub, R. M.; Gopinath, Subash C. B.; Voon, C. H.; Liu, Wei-Wen; Foo, K. L.

    2016-07-01

    In this paper, sol-gel method spin coating technique is adopted to prepare nanoparticles titanium dioxide (TiO2) thin films. The prepared TiO2 sol was synthesized using titanium butoxide act as a precursor and subjected to deposited on the p-type silicon oxide (p-SiO2) and glass slide substrates under room temperature. The effect of different alcoholic solvents of methanol and ethanol on the structural, morphological, optical and electrical properties were systematically investigated. The coated TiO2 thin films were annealed in furnace at 773 K for 1 h. The structural properties of the TiO2 films were examined with X-ray Diffraction (XRD). From the XRD analysis, both solvents showing good crystallinity with anatase phase were the predominant structure. Atomic Force Microscopy (AFM) was employed to study the morphological of the thin films. The optical properties were investigated by Ultraviolet-visible (UV-Vis) spectroscopy were found that ethanol as a solvent give a higher optical transmittance if compare to the methanol solvent. The electrical properties of the nanoparticles TiO2 thin films were measured using two-point-probe technique.

  16. The enhanced conductivity and stability of AZO thin films with a TiO2 buffer layer

    Aluminum doped zinc oxide (AZO) films were substitutes of the SnO2:F films on soda lime glass substrate in the amorphous thin-film solar cells due to good properties and low cost. In order to improve properties of AZO films, the TiO2 buffer layer had been introduced. AZO films with and without TiO2 buffer layer were deposited on soda lime glass substrates by r.f. magnetron sputtering. Subsequently, one group samples were annealed in vacuum (0.1 Pa) at 500 °C for 120 s using the RTA system, and the influence of TiO2 thickness on the properties of AZO films had been discussed. The XRD measurement results showed that all the films had a preferentially oriented (0 0 2) peak, and the intensity of (0 0 2) peak had been enhanced for the AZO films with TiO2 buffer layer. The resistivity of TiO2 (3.0 nm)/AZO double-layer film is 4.76×10-4 Ω cm with the maximum figure merit of 1.92×10-2 Ω-1, and the resistivity has a remarkable 28.7% decrease comparing with that of the single AZO film. The carrier scattering mechanism of TiO2 (3.0 nm)/AZO double-layer film had been described by Hall measurement in different temperatures. The average transmittance of all the films exceeded 92% in the visible spectrum. Another group samples were heat treated in the quartz tube in air atmosphere, and the effect of TiO2 thickness on thermal stability of AZO films had been discussed.

  17. Titanium dioxide (TIO2) thin film and plasma properties in RF magnetron sputtering

    Lately, titanium dioxide (TiO2) films with anatase crystalline property received numerous attentions as unique material properties. There are wide applications of TiO2 thin film such as for photocatalytic application in solar cell. In the present study, radio frequency (RF) magnetron sputtering technique has been used to produce high dense, homogeneously controllable film layer at low deposition temperature using titanium (Ti) target. The diameter of the Ti target is 3 inch with fixed discharge power of 400W. Magnetron sputtering plasma has been produced in high purity 99.99% Argon (Ar) and 99.99% Oxygen (O2) environment pressure ranging from 5 to 20 mTorr. The TiO2 were growth on silicon and glass substrates. Substrate temperature during deposition was kept constant at 400°C. The distance between target and substrate holder was maintain at 14 cm with rotation of 10 rotation-per-minutes. Our X-ray diffraction result, shows anatase crystalline successfully formed with characterization peaks of plane (101) at 2θ = 25.28°, plane (202) at 2θ = 48.05° and plane (211) at 2θ = 55.06°. In addition, it is our interest to study the plasma properties and optical spectrum of Ti, Ti+ , O- , ArM and Ar+ in the chamber during the deposition process. Result of emission line intensities, electron density and temperature from optical spectroscope and Langmuir probe will be discuss further during the workshop. This works were supported by Graduate Incentive Scheme of Universiti Tun Hussein Onn Malaysia (UTHM) and Fundamental Research Grant Scheme of Ministry of Higher Education, Malaysia. (author)

  18. Post-deposition annealing effect on RF-sputtered TiO2 thin-film properties for photonic applications

    Hadjoub, Ilhem; Touam, Tahar; Chelouche, Azeddine; Atoui, Mohamed; Solard, Jeanne; Chakaroun, Mahmoud; Fischer, Alexis; Boudrioua, Azzedine; Peng, Lung-Han

    2016-02-01

    Titanium dioxide (TiO2) thin films were grown on glass substrates at room temperature using RF magnetron sputtering technique. Effect of the post-annealing for 1 h at 400-600 °C on the structural, morphological, optical and waveguide properties was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), UV-visible spectrophotometry and m-lines spectroscopy (MLS). XRD studies show that as-grown and post-annealed TiO2 films exhibit (101) XRD peak corresponding to the anatase phase of TiO2. Higher annealing temperatures result in a significant increase in crystallinity. The grain size values were calculated and found to be about 15-37 nm. From the analyses made on the SEM micrographs and AFM images, it was revealed that the morphology and surface roughness of the thin films were influenced by the heat treatment temperature. The UV-visible spectroscopy analyses show that as-grown TiO2 films were transparent in the visible region with an average transmittance of more than 75 % and the transmittance decreases slightly with an increase in annealing temperature. Annealed TiO2 films also exhibit an increase in the values of direct optical band gap. MLS measurements at 633-nm wavelength put into evidence that TiO2 planar waveguides demonstrate a well-guided fundamental mode for both transverse electric and transverse magnetic polarized light. Moreover, the refractive index was found to increase with temperature and to approach to the anatase TiO2 single-crystal value for the TiO2 film annealed at 600 °C.

  19. Photocatalytic degradation of phenol in aqueous solution using TiO2/Ti thin film photocatalyst

    樊彩梅; 孙彦平; 闵延琴; 郝晓刚; 李新军; 李芳柏

    2003-01-01

    In order to clarify the respective role of the UV light, catalyst, external bias as well as their combined effects on the photodegradation process and to clarify the photocatalytic mechanism under different experimental conditions, a series of experiments were conducted in a shallow pond photoreactor with an effective volume of 100 mL using TiO2/Ti thin film prepared by anodization as photocatalyst. A 300W UV lamp(Emax=365 nm)was used as side light source. The effect of light intensity on photocatalysis was also conducted. The results show that photocatalytic oxidation is an effective method for phenol removal from waters. The degradation rate can be improved by applying an anodic bias to the TiO2/Ti film electrode, phenol can not be decomposed under only 365 nm UV light irradiation even in the presence of hydrogen peroxide. In the range of our research, the phenol removal rate can be described in terms of pseudo-first order kinetics.

  20. Structural and optical studies of nanostructured TiO2–Ge multi-layer thin films

    This paper reports the effects of annealing on structural and optical properties of nanostructured multi-layer TiO2–Ge thin films. These films were characterized using different techniques such as X-ray diffraction, X-ray reflectivity, Rutherford backscattering (RBS), and Fourier Transform Infrared spectroscopy. Annealing was responsible for pronounced changes in structural and optical properties of these films, as associated with changes in their structures, stoichiometry and stress-state. Three sets of TiO2–Ge multi-layer films were deposited by electron beam evaporation and resistive heating with different Ge layer thickness (5, 10 and 15 nm), and TiO2 layer thickness was fixed to 20 nm. The films were annealed in air up to 500 °C for 2 h. RBS studies showed that the layer structure of TiO2–Ge multi-layer films had been formed. The absorption spectra and band gap energy showed a blue shift with decrease in Ge layer thickness. The absorption spectra of these films suggest quantum confinement that increases with annealing temperature before the complete oxidation of Ge. Apparently complete oxidation results in sudden or sharp rise in band gap energy that matches with that of TiO2. RBS study reveals that layered structure of TiO2–Ge multi-layer films is not destroyed by annealing, which may be due to non-wetting behavior of Ge and its oxide with TiO2. These results imply that nanostructured TiO2–Ge multi-layer thin films may be employed as heterojunctions (with tunable band gap energy) based on quantum confinement effects for use in photovoltaics. - Highlights: • Nanostructured multi-layer TiO2–Ge films were deposited by electron beam evaporation. • The layered structure of the films was not destroyed by annealing. • The band gap energy showed a blue shift with Germanium (Ge) layer thickness. • The absorption spectra of these films suggest quantum confinement. • The films with lower Ge thickness oxidize at lower annealing temperatures

  1. Nb-doped TiO2 thin films as photocatalytic materials

    Catalin Adomnitei; Sorin Tascu; Dumitru Luca; Marius Dobromir; Mihaela Girtan; Diana Mardare

    2015-09-01

    Amorphous undoped and Nb-doped films were obtained by the spin coating method. The films have a compact structure, as revealed by scanning electron microscopy, and are very thin, with thickness values under 100 nm. The photocatalytic activity of the films was evaluated by observing the decomposition of an oleic acid solution under UV irradiation, and by studying the change in the optical transmittance of an aqueous solution containing methylene blue, in the presence of the UV-irradiated films. More than 30 h, depending on doping, are needed to recover their initial contact angles before applying oleic acid. The increase of the optical transmittance of the methylene blue solution confirms the photocatalytic degradation of methylene blue on the Nb-doped TiO2 films. X-ray photoelectron spectroscopy studies, performed to detect the presence of the carbon on the irradiated surface of the films, drive to the conclusion that at the surface of the films, even for contact angles close to 0°, the presence of carbon still can be detected, which demonstrates that hydrophilicity is ruled by a different mechanism than photocatalysis.

  2. Investigation of optical, structural and morphological properties of nanostructured boron doped TiO2 thin films

    Savaş Sönmezoǧlu; Banu Erdoǧan; İskender Askeroǧlu

    2013-12-01

    Pure and different ratios (1, 3, 5, 7 and 10%) of boron doped TiO2 thin films were grown on the glass substrate by using sol–gel dip coating method having some benefits such as basic and easy applicability compared to other thin film production methods. To investigate the effect of boron doped on the physical properties of TiO2, structural, morphological and optical properties of growth thin films were examined. 1% boron-doping has no effect on optical properties of TiO2 thin film; however, optical properties vary with > 1%. From X-ray diffraction spectra, it is seen that TiO2 thin films together with doping of boron were formed along with TiB2 hexagonal structure having (111) orientation, B2O3 cubic structure having (310) orientation, TiB0.024O2 tetragonal structure having rutile phase (110) orientation and polycrystalline structures. From SEM images, it is seen that particles together with doping of boron have homogeneously distributed and held onto surface.

  3. Examination of interfacial charge transfer in photocatalysis using patterned CuO thin film deposited on TiO2

    Osako, K; Matsuzaki, K.; Hosono, H.; G. Yin; D. Atarashi; Sakai, E.; Susaki, T.; Miyauchi, M

    2015-01-01

    We examined the interfacial charge transfer effect on photocatalysts using a patterned CuO thin film deposited on a rutile TiO2 (110) substrate. Photocatalytic activity was visualized based on the formation of metal Ag particles resulting from the photoreduction of Ag+ ions under visible-light illumination. Ag particles were selectively deposited near the edge of CuO film for several nanometer thick CuO film, indicating that interfacial excitation from the valence band maximum of TiO2 to the ...

  4. Preparation of cross sections of TiO2 thin films for TEM by ultramicrotomy

    Full text: Considerable research is being carried out on dye-sensitised solar cells, the most extensively studied of which are based on a nanostructured titania semiconducting film deposited on a conducting glass substrate. The preparation of cross-sections of these films is essential for investigating of the shape, size and distribution of the TiO2 particles by TEM. In the present work, we have used a relatively simple and rapid procedure involving ultramicrotomy to prepare cross-sections of the films for initial TEM examination. Titania thin films were produced by screen-printing a nanoparticle titania paste onto SnO2-coated glass substrates, followed by heating in air at 500 deg C for 1 hour. The nanoporous films are optically transparent, have a high surface area, and are 7 to 8 μm thick. The thickness could be checked with a confocal laser scanning microscope using x-z scans in reflection mode. The method for preparing cross-sections was adapted from one used with tissue culture cells on substrates, and which has also been employed with clay minerals. A BEEM capsule half filled with embedding resin was inverted over the glass substrate and TiO2 film, so that the resin was in contact with the film. After polymerisation at 60 deg C overnight, the block was pried away from the glass using a single edged razor blade, leaving the titania film in the resin. The final height of block was about 4-5 mm, and could be directly fitted into an ultramicrotome chuck for sectioning without requiring re-embedding. Ultrathin 60-80 nm sections were cut with a diamond knife, collected on 200 mesh copper grids, then coated with carbon to stabilise the unsupported resin. The sections were examined at 200kV in a Philips CM200 TEM. It was found that the film had detached fully from the glass. The TiO2 grains were observed as mixtures of tetrahedral and rhombohedral geometries with a size distribution in the range 10-25 nm. Anatase and brookite phases present could be identified by

  5. Effect of Annealing on Structure, Morphology, Electrical and Optical Properties of Nanocrystalline TiO2 Thin Films

    B.T. Raut

    2011-01-01

    Full Text Available Semi-transparent and highly conducting nanostructured titanium oxide thin films have been prepared by sol-gel method. Thin films of TiO2 deposited on glass substrates using spin coating technique and the effect of annealing temperature (400 - 700 °C on structural, microstructural, electrical and optical properties were studied. The X-ray diffraction and Atomic force microscopy measurements confirmed that the films grown by this technique have good crystalline tetragonal mixed anatase and rutile phase structure and homogeneous surface. The study also reveals that the rms value of thin film roughness increases from 7 to 19 nm. HRTEM image of TiO2 thin film (annealed at 700 °C shows that a grain of about 50 - 60 nm in size is really aggregate of many small crystallites of around 10 - 15 nm. Electron diffraction pattern shows that the TiO2 films exhibited tetragonal structure. The surface morphology (SEM of the TiO2 film showed that the nanoparticles are fine with an average grain size of about 50 - 60 nm. The optical band gap slightly decreases from 3.26 - 3.24 eV and the dc electrical conductivity was found in the range of 10-6 to 10-5(Ω·cm-1 when the annealing temperature is changed from 400 to 700 °C. It is observed that TiO2 thin film annealed at 700 °C after deposition provide a smooth and flat texture suited for optoelectronic applications.

  6. Plasmonic enhancement of CO2 conversion to methane using sculptured copper thin films grown directly on TiO2

    Columnar Cu nanostructures with tunable lengths are formed directly on porous TiO2 by oblique-angle electron beam evaporation and used as a cocatalyst for photocatalytic conversion of CO2 to methane. A remarkable enhancement in methane production rate is measured using the sculptured copper films with a maximum of 124.3 ppm · cm−2 · h−1 for 160 nm long Cu columnar structures under AM 1.5 illumination. This high methane production rate is attributed to a plasmonic enhancement effect due to the columnar Cu nanostructures. - Highlights: • Cu sculptured thin films (STFs) directly grown on TiO2 catalytic films • Excellent performance in methane production rate by TiO2/Cu STFs films • Enhancement in methane production by plasmonic effect of Cu STFs

  7. Waveguiding Properties of Nano-Structured TiO2 Thin Films Synthesized by Sol-Gel Process

    Znaidi, L.; Touam, T.; Vrel, D.; Kunetsova, I. N.; Fischer, A.; Boudrioua, A.

    2011-12-01

    TiO2 thin films were synthesized by sol-gel process: titanium tetraisopropoxide (TTIP) was dissolved in isopropanol, and then hydrolyzed by adding a water/isopropanol mixture with a controlled hydrolysis ratio. The as prepared sol was deposited by `dip-coating' on a glass substrate with a controlled withdrawal speed. The obtained films were annealed at 350 and 500 °C (2 h). The structural, morphological and optical properties of the prepared films were analyzed by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM). The optical and waveguiding properties of TiO2 films were investigated for both annealing temperatures using m-lines spectroscopy. The results show that our fabricated TiO2 waveguides are multimodes and demonstrate low propagation losses of 0.9 dBṡcm-1.

  8. Sol-Gel TiO2 thin films sensitized with the mulberry pigment cyanidin

    Emerson Henrique de Faria

    2007-12-01

    Full Text Available TiO2 films have various applications, among them solar cells and photodegradation of pollutants. In this study, we investigated TiO2 films functionalized with the organic dye cyanidin extracted from black mulberry (Morus nigra. The TiO2 was functionalized by the sol-gel method and the film was deposited on glass substrates by dip-coating. Our aim was to investigate the interaction between the semiconductor and the dye, as well as the influence of the velocity and number of deposits on the characteristics of the film. Using ultraviolet-visible spectroscopy, we observed a shift from the maximum absorption band at 545 nm for the dye’s ethanol solution to 595 nm for the film, indicating interaction of the cyanidin with the TiO2. The absorption spectra in the infrared region of the functionalized TiO2 particles showed bands characteristic of the oxide and indicated their interaction with the dye. Using profilometry and m-line techniques, we found that the films presented thicknesses in the order of 100 nm. A SEM analysis confirmed the high density of the films.

  9. Low-temperature preparation of high-n TiO2 thin film on glass by pulsed laser deposition

    Ishii, Akihiro; Nakamura, Yoko; Oikawa, Itaru; Kamegawa, Atsunori; Takamura, Hitoshi

    2015-08-01

    Single-phase rutile-type TiO2 thin films with a high refractive index (n) and a low extinction coefficient (k) prepared on glass are expected to improve the performance of anti-reflection coatings. In this study, TiO2 thin films were prepared by the pulsed laser deposition (PLD) method at temperatures ranging from room temperature to 600 °C under an oxygen partial pressure of 1-9 Pa or a 10-5 Pa vacuum, and their crystal structure, microstructure and optical properties were investigated. A single-phase rutile-type TiO2 thin film was successfully prepared on a glass substrate by depositing at room temperature in a vacuum followed by post-annealing at 450 °C in air. A nanocrystalline oxygen-deficient phase in the as-deposited films plays an important role in the formation of the single rutile phase during post-annealing. The single-phase rutile-type TiO2 thin films showed excellent optical properties, with n = 3.14 and k < 0.05 at λ = 400 nm.

  10. A new room temperature gas sensor based on pigment-sensitized TiO2 thin film for amines determination.

    Yanxiao, Li; Xiao-bo, Zou; Xiao-wei, Huang; Ji-yong, Shi; Jie-wen, Zhao; Holmes, Mel; Hao, Limin

    2015-05-15

    A new room temperature gas sensor was fabricated with pigment-sensitized TiO2 thin film as the sensing layer. Four natural pigments were extracted from spinach (Spinacia oleracea), red radish (Raphanus sativus L), winter jasmine (Jasminum nudiflorum), and black rice (Oryza sativa L. indica) by ethanol. Natural pigment-sensitized TiO2 sensor was prepared by immersing porous TiO2 films in an ethanol solution containing a natural pigment for 24h. The hybrid organic-inorganic formed films here were firstly exposed to atmospheres containing methylamine vapours with concentrations over the range 2-10 ppm at room temperature. The films sensitized by the pigments from black-rice showed an excellent gas-sensitivity to methylamine among the four natural pigments sensitized films due to the anthocyanins. The relative change resistance, S, of the films increased almost linearly with increasing concentrations of methylamine (r=0.931). At last, the black rice pigment sensitized TiO2 thin film was used to determine the biogenic amines generated by pork during storage. The developed films had good sensitivity to analogous gases such as putrscine, and cadaverine that will increase during storage. PMID:24934102

  11. Surface Plasmons and Optical Properties of TiO2/X(X = Au and Ag) Nanostructure Thin Films

    Zolanvari, A.; Sadeghi, H.; Norouzi, R.; Ranjgar, A.

    2013-09-01

    TiO2/X(X = Au and Ag) nanolayers are fabricated by depositing TiO2 films using rf magnetron sputtering on thin quartz substrates embedded with Au and Ag nanoparticles. Enhancement of light absorption of the nanostructural layers is observed. These plasmonic and non-plasmonic materials are ordered in geometric arrangements with dimensions that are fractions of the wavelength of light. The light absorption enhancement of synthesized structure in comparison to TiO2 is originated from near-field enhancement caused by the plasmonic effect of metallic nanoparticles, which can be demonstrated by the optical absorption spectra. We show that plasmon modes can exist for the infrared region of the optical spectrum. Also, we analyze the optical properties of the metal-insulator films, in order to clarify the role of metal inclusions in the TiO2 dielectric matrix. Optical band gaps of the nanolayer films are calculated by using Tauc's relation, and the n values of optical band gaps with the variation composition are found from 1.80 to 3.69 eV. Band gap narrowing and absorption in the visible spectral region induced by the incorporation of TiO2/X(X=Au and Ag) nanolayers enable the design of nanostructured thin films to be achieved for photocatalysts and solar energy converters.

  12. The oxidation stability of boron nitride thin films on MgO and TiO2 substrates

    The stability of BN thin film coatings (2--5 nm thick) on MgO and TiO2 substrates was investigated using transmission electron microscopy (TEM). The samples were heated in air for at least 16 hours at temperatures ranging from 773 K--1,273 K. On MgO supports, the BN thin film coating was lost by 1,073 K due to a solid state reaction with the substrate leading to formation of Mg2B2O5. No such reaction occurred with the TiO2 substrate and the BN was stable even at 1,273 K. However, the coating appeared to ball up and phase segregate into islands of near-graphitic BN and clumps of TiO2 (rutile). The oxidizing treatment appears to promote the transformation from turbostratic BN to graphitic BN

  13. Characterization and photocatalytic activity of boron-doped TiO2 thin films prepared by liquid phase deposition technique

    Noor Shahina Begum; H M Farveez Ahmed; O M Hussain

    2008-10-01

    Boron doped TiO2 thin films have been successfully deposited on glass substrate and silicon wafer at 30°C from an aqueous solution of ammonium hexa-fluoro titanate and boron trifluoride by liquid phase deposition technique. The boric acid was used as an – scavenger. The resultant films were characterized by XRD, EDAX, UV and microstructures by SEM. The result shows the deposited film to be amorphous which becomes crystalline between 400 and 500°C. The EDAX and XRD data confirm the existence of boron atom in TiO2 matrix and a small peak corresponding to rutile phase was also found. Boron doped TiO2 thin films can be used as photocatalyst for the photodegradation of chlorobenzene which is a great environmental hazard. It was found that chlorobenzene undergoes degradation efficiently in presence of boron doped TiO2 thin films by exposing its aqueous solution to visible light. The photocatalytic activity increases with increase in the concentration of boron.

  14. Structural and Optical Characteristics of TiO2 Nanoparticles-Containing Mesoporous Silica (SBA-15) Thin Films

    The thin films of ordered mesoporous silica (SBA-15) with nanometer-sized pores have been formed on silicon substrates. It was confirmed that the pores were hexagonally ordered as the stacking of rows of pores and silica walls in the direction normal to the substrate surface. From the results of X-ray reflectivity and diffraction the pore size and wall thickness were evaluated to be ∼4.8 nm and ∼2.1 nm, respectively. Furthermore, titanium dioxide nanoparticles were successfully synthesized in the pores of SBA-15 thin film. X-ray photoelectron spectroscopy of SBA-15 thin film after TiO2 synthesis indicated that the nanoparticles in the pores were titanium dioxide which included a small amount of defects. The optical reflectance of TiO2-containing SBA-15 film decreased at wavelengths shorter than 350 nm as compared with that of SBA-15 film before the TiO2 synthesis, resulting in optical absorption by the TiO2 nanoparticles in the pores of SBA-15.

  15. Surface chemistry and optical property of TiO2 thin films treated by low-pressure plasma

    The low temperature RF plasma treatment was used to control the surface chemistry and optical property of TiO2 thin films deposited by RF magnetron sputtering with a very good uniformity at 300 deg. C substrate heating temperature. The XRD pattern indicates the crystalline structure of the film could be associated to amorphous structure of TiO2 in thin film. The plasma treatment of TiO2 film can increase the proportion of Ti3+ in Ti2p and decrease in carbon atoms as alcohol/ether group in C1s at the surface. The optical transmittance of the film was enhanced by 50% after the plasma treatment. The surface structure and morphology remain the same for untreated and low-pressure plasma-treated films. Therefore, increase in the optical transmission could be due to change in surface chemistry and surface cleaning by plasma treatment. - Graphical abstract: The surface chemistry and surface states of TiO2 films was modified using low-pressure RF plasma treatment. The surface roughness and crystalline structure remain unchanged for low-pressure plasma-treated films. There was an increase in the Ti3+ surface states of Ti2p at the surface and this can be useful to increase the photocatalytic activities of TiO2 films. The proportion of carbon atoms as carboxyl group in C1s was also increased after plasma treatment. All the plasma-treated films show a higher optical transmittance when untreated and it was increased when the power was increased. The increase in the optical transmission could be due to surface cleaning of films by plasma treatment and possibly due to change in the surface chemistry

  16. Hydrophobic–hydrophilic conversion in microfluidic polymer channels with TiO2 thin films

    In this study, recoverable and maintainable hydrophilic micropatterns on polymer-based microfluidic devices were developed through liquid phase deposition of a photocatalytic TiO2. The TiO2-coated region in the microchannel could be hydrophilized through brief UV irradiation upon request. A titanium oxide film was deposited either on bare polymer substrates or on a titanium-sputtered surface using an aqueous TiCl3 solution at 80 °C. A cyclic olefin copolymer (COC) coated with the TiO2 film displayed effective photocatalytic activity, which reduced the water contact angle from 50° to less than 5°. The Ti seed layer was facilitated to pave the substrate with TiO2 grains during the liquid phase deposition. Thus, the photocatalytic effect could be achieved with less number of LPD cycles. Even after contamination from an organic solvent or photoresist, the surface became hydrophilic upon 5 min of UV irradiation. The photocatalytic effect was so stable that super-hydrophilicity of the surface could be promptly recovered after a month of storage under atmospheric conditions. A COC microchannel was fabricated with TiO2 patterns to allow for controlled delivery of the aqueous liquid without the need for external pumps or valves. A hydrogel pattern self-organized along the TiO2 pattern demonstrated a practical application of the recoverable hydrophilicity in microchannels. Functional hydrogels can easily and stably be integrated into a polymer microchannel using this approach

  17. Structural and Electrical Properties of TiO2 Thin Film Derived from Sol-gel Method using Titanium (IV Butoxide

    Isrihetty Senain

    2010-12-01

    Full Text Available Fabrication of titanium dioxide (TiO2 thin film on microscope glass using sol-gel method has been studied intensively. The starting materials were titanium (IV butoxide, ethanol, acetic acid, triton x-100, hydrochloric acid and deionized water. The materials were mixed together to form the sols. Then, the heat and ageing treatment was applied to form stable sols. The sols were then spin coated on the glass substrate to form the homogenous and transparent TiO2 thin film. The TiO2 thin film was coated at several layers using specific conditions. To evaluate the performance of thin film, the crystallinity of the thin film was determined by using the x-ray diffractometer  (XRD. The change on the surface morphology was observed using atomic force microscope (AFM. The electrical property of the thin film was determined by doing the current-voltage (I-V analysis on the thin film. It has been successfully shown that the anatase crystalline phase was observed when the TiO2 thin film was heated at 500°C. The roughness and the crystalline phase of TiO2 thin film changed drastically with the growth conditions. Finally, the effect of film preparation to the film resistivity also showed a critical aspect where we should take into account during the preparation of TiO2 thin film.

  18. Correlation of structural, optical and surface morphological properties of N-doped TiO2 thin films prepared by facing targets sputtering technique

    In this study, N-doped TiO2 films were prepared by facing targets sputtering technique without substrate heating. Nitrogen partial pressure (PN) was varied from 0 Pa to 0.08 Pa to vary the amount of nitrogen doping in TiO2 thin film. The X-ray diffraction study indicates that increase of nitrogen partial pressure increases replacement of oxygen by nitrogen in TiO2 crystal. An abrupt change of crystal structure, crystallinity, porosity and surface morphological property of N-doped TiO2 thin films is observed for the samples, prepared over nitrogen partial pressure 0.05 Pa

  19. Formation of TiO2 Thin Films using NH3 as Catalyst by Metalorganic Chemical Vapor Deposition

    Jung, Sung-Hoon; Kang, Sang-Won

    2001-05-01

    We have studied metalorganic chemical vapor deposition of TiO2 thin films using titanium tetra-isopropoxide [TTIP, Ti(O--C3H7)4] and NH3 as a catalyst at deposition temperatures ranging from 250 to 365°C. At deposition temperatures above 330°C, pyrolytic self-decomposition of TTIP is dominant regardless of the use of NH3, and the activation energy for TiO2 film formation is 152 kJ/mol. At deposition temperatures below 330°C, the films can be formed with the help of the catalytic activity of NH3, and the activation energy is reduced to 55 kJ/mol. TiO2 films deposited through the pyrolytic self-decomposition of TTIP have an anatase structure before and after performing post-deposition annealing in oxygen ambient for 30 min at 750°C. On the other hand, the as-deposited films formed through the catalytic reaction of TTIP with NH3 incorporate nitrogen impurities and have microcrystallites of the rutile structure within the amorphous matrix. However, the post-deposition annealing, the nitrogen impurities are completely removed from the films, and the films are converted into polycrystalline TiO2 films with the rutile structure, which have a high dielectric constant of 82 and a low leakage current.

  20. Photocatalytic degradation of spill oils on TiO2 nanotube thin films

    The nitrogen-doped TiO2 nanotube (N-TNT) thin films were synthesized using ZnO nanorods as the template and doped with urea at 623 K. Under ultraviolet (UV) and visible light irradiation, the efficiencies for photocatalytic degradation of methylene blue is as high as 30%. About 10% of toluene (representing aromatics in the spill oils) in sea water can be photocatalytically degraded under visible light radiation for 120 min. The aliphatic model compound (1-hexadecene) has, on the contrary, a less efficiency (8%) on the N-TNT photocatalyst. On the average, under visible light radiation, the effectnesses of the N-TNT for photocatalytic degradation of model compounds in the spill oils in sea water are 0.38 mg toluene/gN-TNT h and 0.25 mg 1-hexadecene/gN-TNT h. It is expected that spill oils in the harbors or seashores can be adsorbed and photocatalytically degraded on the N-TNT thin films that are coated onto levee at the sea water surface level

  1. Investigations on the synthesis, optical and electrical properties of TiO2 thin films by Chemical Bath Deposition (CBD) method

    Titanium dioxide (TiO2 ) thin films were prepared by Chemical Bath Deposition (CBD) method. The X-ray diffraction (XRD) analysis was used to examine the structure and to determine the crystallite size of TiO2 thin film. The surface morphology of the film was studied using Scanning Electron Microscopy (SEM).The optical properties were studied using the UV-Visible and photoluminescence (PL) spectrum. Optical constants such as band gap, refractive index, extinction coefficient and electric susceptibility were determined. The FTIR spectrum revealed the strong presence of TiO2 . The dielectric properties of TiO2 thin films were studied for different frequencies and different temperatures. The AC electrical conductivity test revealed that the conduction depended both on the frequency and the temperature. Photoconductivity study was carried out in order to ascertain the positive photoconductivity of the TiO2 thin films. (author)

  2. Preparation of anatase TiO2 thin film by low temperature annealing as an electron transport layer in inverted polymer solar cells

    Highlights: • Anatase thin film of TiO2 was prepared by low temperature annealing. • Anatase TiO2 colloidal solution was obtained from amorphous form through solvothermal process. • Anatase TiO2 colloidal solution was used to prepare thin film on ITO glass. • Polymer solar cell fabricated on anatase TiO2 thin film showed 2.6% of PCE. - Abstract: To prepare the anatase TiO2 thin films on ITO glass, amorphous TiO2 colloidal solution was synthesized through the simple sol-gel method by using titanium (IV) isopropoxide as a precursor. This amorphous TiO2 colloidal solution was spread on ITO glass by spin-coating, then treated at 450 °C to obtain anatase TiO2 film (for device A). For other TiO2 films, amorphous TiO2 colloidal solution was treated through solvothermal process at 180 °C to obtain anatase TiO2 colloidal solution. This anatase TiO2 colloidal solution was spread on ITO glass by spin coating, and then annealed at 200 °C (for device B) and 130 °C (for device C), respectively. The average particle size of amorphous TiO2 colloidal solution was about 1.0 nm and that of anatase TiO2 colloidal solution was 10 nm. The thickness of TiO2 films was about 15 nm for all cases. When inverted polymer solar cells were fabricated by using these TiO2 films as an electron transport layer, the device C showed the highest PCE (2.6%) due to the lack of defect, uniformness and high light absorbance of TiO2 films. The result of this study can be applied for the preparation of inverted polymer solar cell using TiO2 films as a buffer layer at low temperature on plastic substrate by roll-to roll process

  3. Electrical property measurements of Cr-N codoped TiO2 epitaxial thin films grown by pulsed laser deposition,

    Jacimovic, Jacim; Gaal, Richard; Magrez, Arnaud; Forró, László; Regmi, Mauri; Eres, Gyula

    2013-01-01

    The temperature dependent resistivity and thermo-electric power of Cr-N codoped TiO2 were compared with that of single element N and Cr doped and undoped TiO2 using epitaxial anatase thin films grown by pulsed laser deposition on (100) LaAlO3 substrates. The resistivity plots and especially the thermoelectric power data confirm that codoping is not a simple sum of single element doping. However, the negative sign of the Seebeck coefficient indicates electron dominated transport independent of...

  4. Self-Assembled Multilayer Structure and Enhanced Thermochromic Performance of Spinodally Decomposed TiO2-VO2 Thin Film.

    Sun, Guangyao; Zhou, Huaijuan; Cao, Xun; Li, Rong; Tazawa, Masato; Okada, Masahisa; Jin, Ping

    2016-03-23

    Composite films of VO2-TiO2 were deposited on sapphire (11-20) substrate by cosputtering method. Self-assembled well-ordered multilayer structure with alternating Ti- and V-rich epitaxial thin layer was obtained by thermal annealing via a spinodal decomposition mechanism. The structured thermochromic films demonstrate superior optical modulation upon phase transition, with significantly reduced transition temperature. The results provide a facile and novel approach to fabricate smart structures with excellent performance. PMID:26937588

  5. Preparation of TiO2 thin film by the LPD method on functionalized organic self-assembled monolayers

    2009-01-01

    In this paper, uniform titania (TiO2) films have been formed at 50℃ on silanol SAMs by the liquid-phase deposition (LPD) method at a temperature below 100℃. OTS (Octadecyltrichloro-Silane) selfassembled monolayers (SAMs) on glass wafers were used as substrates for the deposition of titanium dioxide thin films. This functionalized organic surface has shown to be effective for promoting the growth of films from titanic aqueous solutions by the LPD method at a low temperature below 100℃. The crystal phase composition, microstructure and topography of the as-prepared films were characterized by various techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The results indicate that the as-prepared thin films are purely crystallized anatase TiO2 constituted by nanorods after being annealed at 500℃. The pH values, concentration of reactants, and deposition temperatures play important roles in the growth of TiO2 thin films.

  6. Preparation of TiO2 thin film by the LPD method on functionalized organic self-assembled monolayers

    HE ZhongLiang; YU ZhiWei; MIAO HongYan; TAN GuoQiang; LIU Yan

    2009-01-01

    In this paper, uniform titania (TiO2) films have been formed at 50℃ on silanol SAMs by the liquid-phase deposition (LPD) method at a temperature below 100℃. OTS (Octadecyltrichloro-Silane) self-assembled monolayers (SAMs) on glass wafers were used as substrates for the deposition of titanium dioxide thin films. This functionalized organic surface has shown to be effective for promoting the growth of films from titanic aqueous solutions by the LPD method at a low temperature below 10012. The crystal phase composition, microstructure and topography of the as-prepared films were characterized by various techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The results indicate that the as-prepared thin films are purely crystallized anatase TiO2 constituted by nanorods after being annealed at 500℃. The pH values, concentration of reactants, and deposition temperatures play important roles in the growth of TiO2 thin films.

  7. Role of water adsorption in photoinduced superhydrophilicity on TiO2 thin films

    The ultraviolet (UV) irradiation of a titanium dioxide (TiO2) film surface gives rise to two simultaneous phenomena: photocatalysis and superhydrophilicity. Photocatalysis has been thoroughly studied, but the mechanism governing superhydrophilicity remains controversial. The authors' investigations show the effects induced by UV irradiation on the water adsorption and desorption on the TiO2 surface. The observations prove that superhydrophilicity cannot be solely induced by the removal of organic contamination via photocatalysis, but is associated with water adsorption most probably due to the appearance of hydroxyl groups on surface defects

  8. Nanocrystalline Pt-doped TiO2 thin films prepared by spray pyrolysis for hydrogen gas detection

    Lalchand A Patil; Dinesh N Suryawanshi; Idris G Pathan; Dhanashri G Patil

    2014-05-01

    Nanostructured pure and Pt-doped TiO2 thin films were prepared by chemical spray pyrolysis technique. Aqueous solution of TiCl3.6H2O (0.01 M) was chosen as the starting solution for the preparation of pure TiO2 thin film. Aqueous solutions of PtCl6.6H2O (0.01 M) and TiCl3.6H2O (0.01 M) were mixed in volume % of 1 : 99, 2.5 : 97.5 and 5 : 95 respectively to obtain Pt-doped TiO2 thin films. The solutions were sprayed onto quartz substrate heated at 350 °C temperature to obtain the films. These thin films were fired for one hour at 550 °C. The sensing performance of these films was tested for various gases such as LPG, H2, CO2, ethanol, NH3 and Cl2 (1000 ppm). The Pt-doped TiO2 (1 : 99) was observed to be most sensitive (572) to H2 at 400 °C with high selectivity against other gases. Its response time was short (10 s) and recovery was also fast (14 s). To understand the reasons behind the gas-sensing performance of the films, their structural and micro-structral properties were studied using X-ray diffraction and electron microscopy (FE–SEM and TEM), respectively. Thicknesses of all these samples were determined using Surface Profiler. The results are interpreted.

  9. Heteroepitaxial growth and structural characterization of rutile TiO2 thin films on GaN (0 0 0 1) templates prepared by pulsed laser deposition

    Rutile TiO2 (1 0 0) thin films have been prepared on GaN (0 0 0 1) surfaces in the temperature range 300–600 °C by pulsed laser deposition (PLD) method. The effects of both the oxygen pressure and the substrate temperature on the properties of the TiO2 films were investigated. TiO2 thin films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microscope (TEM). Optimum parameters have been determined for growing high-quality TiO2 thin films with a sharp interface, in which the epitaxial orientation relationship between rutile TiO2 and GaN is TiO2 [001] //GaN [112¯0]. The surface morphology of TiO2 thin films exhibited a marked dependence on the substrate temperature, and the better crystallinity of the TiO2 thin films can be obtained at lower oxygen pressure

  10. Surface functionalization of cyclic olefin copolymer (COC) with evaporated TiO2 thin film

    El Fissi, Lamia; Vandormael, Denis; Houssiau, Laurent; Francis, Laurent A.

    2016-02-01

    Cyclic olefin copolymer (COC) is a new class of thermoplastic polymers used for a variety of applications ranging from bio-sensing to optics. However, the hydrophobicity of native COC hampers the further development and application of this material [1]. In this work, we report the structural, morphological, and optical properties of the TiO2/COC hybrid material, which provides a desirable substrate for optical devices and subsequent surface modifications. The TiO2 film on COC substrate was deposited by the evaporation method, and it was characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), profilometry and atomic force microscope (AFM). Using an UV-vis spectrophotometer, we found that the transmittance of the TiO2/COC hybrid material in the visible domain reached 80%. The TiO2/COC hybrid appeared to be stable in most of the assessed polar solvents and acid/basic solutions. The new TiO2/COC hybrid material and the robust fabrication method are expected to enable a variety of BioMEMS applications.

  11. Properties of sputtered TiO2 thin films as a function of deposition and annealing parameters

    The influence of sputtering parameters and annealing on the structure and optical properties of TiO2 thin films deposited by RF magnetron sputtering is reported. A pure TiO2 target was used to deposit the films on Si(100) and glass substrates, and Ar/O2 gas mixture was used for sputtering. It was found that both the structure and the optical properties of the films depend on deposition parameters and annealing. In all cases the as-deposited films were oxygen deficient, which could be compensated by post-deposition annealing. Changes in the Ar/O2 mass flow rate affected the films from an amorphous-like structure for samples deposited without oxygen to a structure where nano-crystalline rutile phase is detected in those deposited with O2. Annealing of the samples yielded growth of both, rutile and anatase phases, the ratio depending on the added oxygen content. Increasing mass flow rate of O2 and annealing are responsible for lowering of the energy band gap values and the increase in refractive index of the films. The results can be interesting towards the development of TiO2 thin films with defined structure and properties

  12. Preparation of Oleyl Phosphate-Modified TiO2/Poly(methyl methacrylate Hybrid Thin Films for Investigation of Their Optical Properties

    Masato Fujita

    2015-01-01

    Full Text Available TiO2 nanoparticles (NPs modified with oleyl phosphate were synthesized through stable Ti–O–P bonds and were utilized to prepare poly(methyl methacrylate- (PMMA- based hybrid thin films via the ex situ route for investigation of their optical properties. After surface modification of TiO2 NPs with oleyl phosphate, IR and 13C CP/MAS NMR spectroscopy showed the presence of oleyl groups. The solid-state 31P MAS NMR spectrum of the product revealed that the signal due to oleyl phosphate (OP shifted upon reaction, indicating formation of covalent Ti–O–P bonds. The modified TiO2 NPs could be homogeneously dispersed in toluene, and the median size was 16.1 nm, which is likely to be sufficient to suppress Rayleigh scattering effectively. The TEM images of TiO2/PMMA hybrid thin films also showed a homogeneous dispersion of TiO2 NPs, and they exhibited excellent optical transparency even though the TiO2 content was 20 vol%. The refractive indices of the OP-modified TiO2/PMMA hybrid thin films changed higher with increases in TiO2 volume fraction, and the hybrid thin film with 20 vol% of TiO2 showed the highest refractive index (n = 1.86.

  13. Influence of thickness and air annealing on structural, morphological, compositional, electrical properties of sprayed TiO2 thin films

    R.SHASHIDHAR

    2013-04-01

    Full Text Available TiO2 thin films were prepared by spray pyrolysis technique at a substrate temperature of 3500C under optimum conditions. Films have uniform thickness varying from 0.3–6 μm and good adhesion to substrate. The films were characterized by XRD, SEM and EDAX measurements. XRD profile shows poly crystalline nature of films. As deposited films have anatase phase. Transformation from anatase to anatase–rutile mixed phase may be due to annealing at 4000C and thickness variation of films. The microstructural properties such as crystallite size, microstrain and dislocation density found to increase due to concentration of lattice imperfections and crystallization of amorphous TiO2 films. SEM micrographs exhibit spherical, square, flower shaped grains and grain boundary formation. EDAX analysis revealed the formation of stoichiometric TiO2 films. Electrical studies show that the films are of n-type nature and increase in resistivity is attributed to surface oxidation and formation of Ti2O3 structure, a perfect insulator.

  14. Effect of C doping on the structural and optical properties of sol-gel TiO2 thin films

    Undoped and C-doped TiO2 thin films have been prepared by sol-gel process. Their structure and optical properties have been investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-vis spectroscopy. It has been observed that C dopants retard the transformation from anatase-to-rutile phase. Namely, C doping effect is attributed to the anatase phase stabilization. The optical analyses show that the optical band gap of anatase C-doped TiO2 decreases with increasing amount of C. Also, it is founded that C dopants have been shown to make TiO2 have a visible light photoresponse.

  15. Thickness-dependent photocatalytic performance of nanocrystalline TiO2 thin films prepared by sol-gel spin coating

    Wu, Chung-Yi; Lee, Yuan-Ling; Lo, Yu-Shiu; Lin, Chen-Jui; Wu, Chien-Hou

    2013-09-01

    TiO2 nanocrystalline thin films on soda lime glass have been prepared by sol-gel spin coating. The thin films were characterized for surface morphology, crystal structure, chemical composition, thickness, and transparency by atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ellipsometry, and UV-vis spectrophotometry. The films prepared by titanium tetraisopropoxide (TTIP) as the precursor under pH of 3.5 ± 0.5 and with calcination temperature of 450 ̊C for 3 h exhibited superior homogeneous aggregation, good optical transparency, superhydrophilicity, and reliable thickness. The effect of film thickness on the photocatalytic degradation of acid yellow 17 was investigated under UV irradiation. The photocatalytic activity was strongly correlated with the number of coatings and followed Langmuir-type kinetics. Under the same film thickness, TiO2 thin films prepared by 0.1 M TTIP exhibited more efficient photocatalytic activity than those prepared by 0.3 M TTIP. For thin films prepared by 0.1 M TTIP, the maximum specific photocatalytic activity occurred at 5 coatings with thickness of 93 ± 1 nm. A model was proposed to rationalize the dependence of the film thickness on the photocatalytic activity, which predicts the existence of an optimum film thickness.

  16. Synthesis and characterization of the Pd/InVO4-TiO2 co-doped thin films with visible light photocatalytic activities

    Novel Pd/InVO4-TiO2 thin films with visible light photocatalytic activity were synthesized from the Pd and InVO2 co-doped TiO2 sol via sol-gel method. The photocatalytic activities of Pd/InVO4-TiO2 thin films were investigated based on the oxidative decomposition of methyl orange in aqueous solution. The as-prepared samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and UV-vis absorption spectroscopy (UV-vis). The results indicate that the Pd/InVO4-TiO2 thin films are compact, uniform and consist of sphere nanoparticles with diameters about 80-100 nm. The UV-vis spectra show that the Pd/InVO4-TiO2 thin films extend the light absorption spectrum toward the visible region. XPS results reveal that doped Pd exist in the form of metallic palladium. The photocatalytic experiments demonstrate that Pd doping can effectively enhance the photocatalytic activities of InVO4-TiO2 thin films in decomposition of aqueous methyl orange under visible light irradiation. It has been confirmed that Pd/InVO4-TiO2 thin films could be excited by visible light (E 4 doped in the films

  17. A Spectroscopic Ellipsometry Study of TiO2 Thin Films Prepared by dc Reactive Magnetron Sputtering: Annealing Temperature Effect

    Mati Horprathum; Pongpan Chindaudom; Pichet Limsuwan

    2007-01-01

    TiO2 thin Rims are obtained by dc reactive magnetron sputtering. A target of titanium (99.995%) and a mixture of argon and oxygen gases are used to deposit TiO2 films on to silicon wafers (100). The crystalline structure of deposited and annealed film are deduced by variable-angle spectroscopic ellipsometry (VASE) and supported by x-ray diffractometry. The optical properties of the Sims are examined by VASE. Measurements of ellipsometry are performed in the spectral range 0.72-3.55 eV at incident angle 75°. Several SE models, categorized by physical and optical models, are proposed based on the 'simpler better' rule and curve-fits, which are generated and compared to the experimental data using the regression analysis. It has been found that the triple-layer physical model together with the Cody-Lorentz dispersion model offer the most convincing result. The as-deposited films are found to be inhomogeneous and amorphous, whereas the annealed films present the phase transition to anatase and rutile structures. The refractive index of TiO2 thin films increases with annealing temperature. A more detailed analysis further reveals that thickness of the top sub-layer increases, whereas the region of the bottom amorphous sub-layer shrinks when the films are annealed at 300°C.

  18. ALD TiO2 thin film as dielectric for Al/p-Si Schottky diode

    Sefa B K Aydin; Dilber E Yildiz; Hatice Kanbur Çavuş; Recep Şahingöz

    2014-12-01

    Electrical analysis of Al/p-Si Schottky diode with titanium dioxide (TiO2) thin film was performed at room temperature. The forward and reverse bias current–voltage (–) characteristics of diode were studied. Using thermionic emission (TE) theory, the main electrical parameters of the Al/TiO2/p-Si Schottky diode such as ideality factor (), zero bias barrier height (Bo) and series resistance (s) were estimated from forward bias – plots. At the same time, values of , Bo and s were obtained from Cheung’s method. It was shown that electrical parameters obtained from TE theory and Cheung’s method exhibit close agreement with each other. The reverse-bias leakage current mechanism of Al/TiO2/p-Si Schottky barrier diodes was investigated. The – curves in the reverse direction are taken and interpreted via both Schottky and Poole–Frenkel effects. Schottky effect was found to be dominant in the reverse direction. In addition, the capacitance–voltage (–) and conductance–voltage (/–) characteristics of diode were investigated at different frequencies (50–500 kHz). The frequency dependence of interface states density was obtained from the Hill–Coleman method and the voltage dependence of interface states density was obtained from the high–low frequency capacitance method.

  19. Localised modifications of anatase TiO2 thin films by a Focused Ion Beam

    A Focused Ion Beam (FIB) has been used to implant micrometer-sized areas of polycrystalline anatase TiO2 thin films with Ga+ ions using fluencies from 1015 to 1017 ions/cm2. The evolution of the surface morphology was studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). In addition, the chemical modifications of the surface were followed by X-ray photoelectron spectroscopy (XPS). The implanted areas show a noticeable change in surface morphology as compared to the as-deposited surface. The surface loses its grainy morphology to gradually become a smooth surface with a RMS roughness of less than 1 nm for the highest ion fluence used. The surface recession or depth of the irradiated area increases with ion fluence, but the rate with which the depth increases changes at around 5 x 1016 ions/cm2. Comparison with implantation of a pre-irradiated surface indicates that the initial surface morphology may have a large effect on the surface recession rate. Detailed analysis of the XPS spectra shows that the oxidation state of Ti and O apparently does not change, whereas the implanted gallium exists in an oxidation state related to Ga2O3.

  20. Optical properties analysis of Ta-doped TiO2 thin films on LaAlO3 substrates

    We study optical properties of Ta-doped TiO2 thin film on LaAlO3 substrate using spectroscopy ellipsometry (SE) analysis at energy range of 0.5 – 6.5 eV. Room temperature SE data for Ψ (amplitude ratio) and Δ (phase difference) between p- and s- polarized light waves are taken with multiple incident angles at several spots on the samples. Here, absorption coefficient has been extracted from SE measurements at photon incident angle of 70° for different Ta concentration (0.01, 0.4, and 5 at. %). Multilayer modelling is performed which takes into account reflections at each interface through Fresnel coefficients to obtain reasonably well the fitting of Ψ and Δ data simultaneously. As the results, we estimate that film thickness increases by increasing Ta concentration accompanied by the formation of a new electronic structure. By increasing Ta impurities, the blueshift of absorption coefficient (α) peaks is observable. This result indicates that TiO2 thin film becomes optically resistive by introducing Ta doping. Schematic model of interband transition inTiO2:Ta will be proposed base on obtained optical properties. This study enables us to predict the role of Ta doping on the electronic and optical band structures of TiO2 thin film

  1. 大规模生产TiO2薄膜的方法%Approach for Producing TiO2 Thin Films in Large Scale

    汪洋; 彭晓光; 陈樱

    2007-01-01

    @@ Introduction Metal oxides are in use as catalysts in industrial processes. The surfaces of titanium dioxide (TiO2)has been of great interest because of its capability of heterogeneous catalysis and photocatalysis, and the adsorption of small molecules on TiO2 has received considerable attention in relation to the elimination of atmospheric pollutants. So that It is important to produce TiO2 thin films in large scale.

  2. Photocatalytic degradation of TCE in air using TiO2 porous thin films:Influence of the relative humidity

    Suárez, S.; Arconada, N.; De Castro, Y; Coronado, J.; Portela,R; Durán, A.; B. Sánchez

    2011-01-01

    Porous TiO2-anatase thin films were prepared by the sol-gel route and used for the study of the influence of structural properties in their photocatalytic activity. Sols were prepared by using titanium isopropoxide with two types of modifier ligands, namely acetic acid and acetyl acetone, and pore generating agents such as polyethylene glycol, pluronic F-127 and polyethylene glycol hexadecyl ether (Brij 58). The photocatalytic activity for the degradation of trichloroethylene i...

  3. Radio Frequency Magnetron Sputtering Deposition of TiO2 Thin Films and Their Perovskite Solar Cell Applications

    Cong Chen; Yu Cheng; Qilin Dai; Hongwei Song

    2015-01-01

    In this work, we report a physical deposition based, compact (cp) layer synthesis for planar heterojunction perovskite solar cells. Typical solution-based synthesis of cp layer for perovskite solar cells involves low-quality of thin films, high-temperature annealing, non-flexible devices, limitation of large-scale production and that the effects of the cp layer on carrier transport have not been fully understood. In this research, using radio frequency magnetron sputtering (RFMS), TiO2 cp lay...

  4. Photocatalytic degradation of methylene blue by TiO2-Cu thin films: Theoretical and experimental study

    Research highlights: → The depth and surface Cu dopant concentration can be modulated by thermal treatment of TiO2. → H2O2 can be degraded by TiO2 electron/hole pair as well as by Cu metallic and ionic species, trough of a Like-Fenton mechanism. → The colorant degradation occurs due successive hydoxylations. - Abstract: In this work the effect of doping concentration and depth profile of Cu atoms on the photocatalytic and surface properties of TiO2 films were studied. TiO2 films of about 200 nm thickness were deposited on glass substrates on which a thin Cu layer (5 nm) was deposited. The films were annealed during 1 s to 100 deg. C and 400 deg. C, followed by chemical etching of the Cu film. The grazing incidence X-ray fluorescence measurements showed a thermal induced migration of Cu atoms to depths between 7 and 31 nm. The X-ray photoelectron spectroscopy analysis detected the presence of TiO2, Cu2O and Cu0 phases and an increasing Cu content with the annealing temperature. The change of the surface properties was monitored by the increasing red-shift and absorption of the ultraviolet-visible spectra. Contact angle measurements revealed the formation of a highly hydrophilic surface for the film having a medium Cu concentration. For this sample photocatalytic assays, performed by methylene blue discoloration, show the highest activity. The proposed mechanism of the catalytic effect, taking place on Ti/Cu sites, is supported by results obtained by theoretical calculations.

  5. Influence of the growth parameters on TiO2 thin films deposited using the MOCVD method

    Bernardi M. I. B.

    2002-01-01

    Full Text Available In this work we report the synthesis of TiO2 thin films by the Organometallic Chemical Vapor Deposition (MOCVD method. The influence of deposition parameters used during the growth in the obtained structural characteristics was studied. Different temperatures of the organometallic bath, deposition time, temperature and type of the substrate were combined. Using Scanning Electron Microscopy associated to Electron Dispersive X-Ray Spectroscopy, Atomic Force Microscopy and X-ray Diffraction, the strong influence of these parameters in the thin films final microstructure was verified.

  6. TRANSPARENT SUPERHYDROPHILIC SiO2/TiO2/SiO2 TRI-LAYER NANOSTRUCTURED ANTIFOGGING THIN FILM

    Eshaghi A.

    2013-09-01

    Full Text Available SiO2/TiO2/SiO2 thin films were deposited on glass substrates using an electron beam physical vapor deposition technique. The structure, morphology, surface composition, surface roughness, optical properties, and hydrophilic properties of the thin film were investigated. The structure measurement shows that only anatase phase was exhibited in the thin film. In the TiO2 thin film, the crystals nucleated from the thin films was homogeneous and the average crystalline sizes were 35 nm. The transmittance spectra of the films revealed transparency in the visible region of the spectrum. SiO2/TiO2/SiO2 thin film showed better hydrophilicity under irradiation and storage in comparison to SiO2/TiO2 thin film. SiO2/TiO2/SiO2 tri-layer thin film showed superhydrophilicity which greatly encourages the antifogging function of the film.

  7. Adsorption and solar light decomposition of acetone on anatase TiO2 and niobium doped TiO2 thin films.

    Mattsson, Andreas; Leideborg, Michael; Larsson, Karin; Westin, Gunnar; Osterlund, Lars

    2006-01-26

    Adsorption and solar light decomposition of acetone was studied on nanostructured anatase TiO2 and Nb-doped TiO2 films made by sol-gel methods (10 and 20 mol % NbO2.5). A detailed characterization of the film materials show that films contain only nanoparticles with the anatase modification with pentavalent Nb oxide dissolved into the anatase structure, which is interpreted as formation of substituted Nb=O clusters in the anatase lattice. The Nb-doped films displayed a slight yellow color and an enhanced the visible light absorption with a red-shift of the optical absorption edge from 394 nm for the pure TiO2 film to 411 nm for 20 mol % NbO2.5. In-situ Fourier transform infrared (FTIR) transmission spectroscopy shows that acetone adsorbs associatively with eta1-coordination to the surface cations on all films. On Nb-doped TiO2 films, the carbonyl bonding to the surface is stabilized, which is evidenced by a lowering of the nu(C=O) frequency by about 20 cm(-1) to 1672 cm(-1). Upon solar light illumination acetone is readily decomposed on TiO2, and stable surface coordinated intermediates are formed. The decomposition rate is an order of magnitude smaller on the Nb-doped films despite an enhanced visible light absorption in these materials. The quantum yield is determined to be 0.053, 0.004 and 0.002 for the pure, 10% Nb:TiO2, and 20%Nb:TiO2, respectively. Using an interplay between FTIR and DFT calculations we show that the key surface intermediates are bidentate bridged formate and carbonate, and H-bonded bicarbonate, respectively, whose concentration on the surface can be correlated with their heats of formation and bond strength to coordinatively unsaturated surface Ti and Nb atoms at the surface. The oxidation rate of these intermediates is substantially slower than the initial acetone decomposition rate, and limits the total oxidation rate at t>7 min on TiO2, while no decrease of the rate is observed on the Nb-doped films. The rate of degradation of key surface

  8. Analysis The Electrical Properties of Co, TiO2 and Co/TiO2 Multilayer Thin Films of Different Thickness Deposited by EBeam Technique.

    Md. Faruk Hossain

    2015-10-01

    Full Text Available This paper presents the fabrication of the Co doped TiO2 film for studying the electrical properties. In this case, at first Co/TiO2 multilayer films were prepared by e-beam evaporation in a vacuum better than 10-5 Torr. The electrical properties of the deposited Co, TiO2, Co/TiO2 films had been studied. The surface morphology had been studied by Atomic Force Microscopy. In the multilayer, the thickness of Co and TiO2 was kept same. Each layer thickness was varied from 5nm to 15 nm and repeated three times. The deposition rate of the Co and TiO2 thin films are about 1.33 nm/sec &.1.25 nm/sec respectively. Electrical conductivity for the deposited Co, TiO2 and Co/TiO2 multilayer thin films had been measured as a function of temperature ranging from 300K to 470K. The deposited Co thin film, conductivity is of the order of 106 (Ω-m- 1 that decreases with increasing temperature and the value for deposited TiO2 and Co/TiO2 multilayer thin films is of the order of 102 (Ω-m-1 and 105 (Ω-m-1 respectively. Again, the conductivity of the deposited TiO2 thin films decreases with film thickness where in the case of as deposited Co, Co/ TiO2 multilayer thin films increases with increasing film thickness. The sheet resistance of the as deposited Co thin films increases with increasing temperature which is to be the order of 102 Ω/sheet. It is found that the sheet resistance of the as deposited TiO2 and Co/TiO2 multilayer thin films to be the order of 107 Ω/sheet and 102 Ω/sheet respectively which decreases with increasing temperature. Variation of temperature coefficient of resistance (T.C.R for Co and TiO2 thin films are metallic and insulating in nature respectively. The T.C.R. of deposited Co/TiO2 multilayer thin films in all cases are semiconducting in nature.

  9. Directly patterned TiO2 nanostructures for efficient light harvesting in thin film solar cells

    Ram, Sanjay K.; Rizzoli, Rita; Desta, Derese; Jeppesen, Bjarke R.; Bellettato, Michele; Samatov, Ivan; Tsao, Yao-Chung; Johannsen, Sabrina R.; Neuvonen, Pekka T.; Pedersen, Thomas Garm; Pereira, Rui N.; Pedersen, Kjeld; Balling, Peter; Nylandsted Larsen, Arne

    2015-09-01

    A novel, scalable, and low-cost strategy for fabricating sub-wavelength scale hierarchical nanostructures by direct patterning of TiO2 nanoparticles on glass substrates is reported. Two nanostructural designs of light-trapping back-surface reflectors (BSR) have been fabricated for increasing the photon-harvesting properties of thin-film solar cells: a quasi-periodic nano-crater design and a random nano-bump design. The efficient light-scattering properties of the nano-crater design over a broad wavelength range are demonstrated by the measured haze factor being larger than 40% at wavelengths (~700 nm) near the band edge of amorphous silicon (a-Si:H). The a-Si:H-based n-i-p solar cell fabricated with an only ~200 nm thick absorber layer on the nano-crater BSR shows a short-circuit current density (J sc) of ~16.1 mA cm-2 representing a 28% enhancement compared to the cell deposited on a non-textured flat substrate. Measurements of the external quantum efficiency of the cell fabricated on the quasi-periodic nano-crater surface at long wavelengths, λ  >  700 nm, demonstrate an increase of a factor of 5 relative to that of a flat reference solar cell. The theoretical modeling results of optical absorption corroborate well with the experimental findings and are used to identify the volumes of strong optical absorption in the a-Si:H active layer of the textured BSR devices.

  10. Directly patterned TiO2 nanostructures for efficient light harvesting in thin film solar cells

    A novel, scalable, and low-cost strategy for fabricating sub-wavelength scale hierarchical nanostructures by direct patterning of TiO2 nanoparticles on glass substrates is reported. Two nanostructural designs of light-trapping back-surface reflectors (BSR) have been fabricated for increasing the photon-harvesting properties of thin-film solar cells: a quasi-periodic nano-crater design and a random nano-bump design. The efficient light-scattering properties of the nano-crater design over a broad wavelength range are demonstrated by the measured haze factor being larger than 40% at wavelengths (∼700 nm) near the band edge of amorphous silicon (a-Si:H). The a-Si:H-based n-i-p solar cell fabricated with an only ∼200 nm thick absorber layer on the nano-crater BSR shows a short-circuit current density (J sc) of ∼16.1 mA cm−2 representing a 28% enhancement compared to the cell deposited on a non-textured flat substrate. Measurements of the external quantum efficiency of the cell fabricated on the quasi-periodic nano-crater surface at long wavelengths, λ  >  700 nm, demonstrate an increase of a factor of 5 relative to that of a flat reference solar cell. The theoretical modeling results of optical absorption corroborate well with the experimental findings and are used to identify the volumes of strong optical absorption in the a-Si:H active layer of the textured BSR devices. (paper)

  11. Mechanical characterization of thin TiO2 films by means of microelectromechanical systems-based cantilevers.

    Adami, A; Decarli, M; Bartali, R; Micheli, V; Laidani, N; Lorenzelli, L

    2010-01-01

    The measurement of mechanical parameters by means of microcantilever structures offers a reliable and accurate alternative to traditional methods, especially when dealing with thin films, which are extensively used in microfabrication technology and nanotechnology. In this work, microelectromechanical systems (MEMS)-based piezoresistive cantilevers were realized and used for the determination of Young's modulus and residual stress of thin titanium dioxide (TiO(2)) deposited by sputtering from a TiO(2) target using a rf plasma discharge. Films were deposited at different thicknesses, ranging from a few to a hundred nanometers. Dedicated silicon microcantilevers were designed through an optimization of geometrical parameters with the development of analytical as well as numerical models. Young's modulus and residual stress of sputtered TiO(2) films were assessed by using both mechanical characterization based on scanning profilometers and piezoresistive sensing elements integrated in the silicon cantilevers. Results of MEMS-based characterization were combined with the tribological and morphological properties measured by microscratch test and x-ray diffraction analysis. PMID:20113131

  12. Mechanical characterization of thin TiO2 films by means of microelectromechanical systems-based cantilevers

    The measurement of mechanical parameters by means of microcantilever structures offers a reliable and accurate alternative to traditional methods, especially when dealing with thin films, which are extensively used in microfabrication technology and nanotechnology. In this work, microelectromechanical systems (MEMS)-based piezoresistive cantilevers were realized and used for the determination of Young's modulus and residual stress of thin titanium dioxide (TiO2) deposited by sputtering from a TiO2 target using a rf plasma discharge. Films were deposited at different thicknesses, ranging from a few to a hundred nanometers. Dedicated silicon microcantilevers were designed through an optimization of geometrical parameters with the development of analytical as well as numerical models. Young's modulus and residual stress of sputtered TiO2 films were assessed by using both mechanical characterization based on scanning profilometers and piezoresistive sensing elements integrated in the silicon cantilevers. Results of MEMS-based characterization were combined with the tribological and morphological properties measured by microscratch test and x-ray diffraction analysis.

  13. Surface Modification of Aerosol-Assisted CVD Produced TiO2 Thin Film for Dye Sensitised Solar Cell

    SuPei Lim

    2014-01-01

    Full Text Available We report a simple and convenient method for the preparation of Ag/TiO2 thin films supported on indium tin oxide, which was achieved by sonochemical deposition of Ag+ on aerosol-assisted chemical vapour deposited TiO2 thin films. Posttreatment was performed on the film by immersion in HCl. The as-prepared composite film was characterised by X-ray diffraction, ultraviolet-visible absorption spectroscopy, Raman spectroscopy, and field emission scanning electron microscopy. The photoelectrochemical measurements and J-V characterisation showed approximately fivefold increase in photocurrent density generation and approximately sevenfold enhancement in dye sensitiser solar cell (DSSC conversion efficiency, which was achieved after modification of the TiO2 film with HCl posttreatment and Ag particle deposition. The improved photocurrent density of 933.30 μA/cm2, as well as DSSC power conversion efficiency of 3.63% with high stability, is an indication that the as-synthesised thin film is a potential candidate for solar energy conversion applications.

  14. Electrical and structural properties of TiO2‑δ thin film with oxygen vacancies prepared by RF magnetron sputtering using oxygen radical

    Kawamura, Kinya; Suzuki, Naoya; Tsuchiya, Takashi; Shimazu, Yuichi; Minohara, Makoto; Kobayashi, Masaki; Horiba, Koji; Kumigashira, Hiroshi; Higuchi, Tohru

    2016-06-01

    Anatase TiO2‑δ thin film was prepared by RF magnetron sputtering using oxygen radical and Ti-metal target. Degrees of the TiO2‑δ crystal orientation in the thin film depends of the oxygen gas pressure (P\\text{O2}) in the radical gun. The (004)- and (112)-oriented TiO2‑δ thin films crystallized without postannealing have the mixed valence Ti4+/Ti3+ state. The electrical conductivities, which corresponds to n-type oxide semiconductor, is higher in the case of (004)-oriented TiO2‑δ thin film containing with high concentration of oxygen vacancy. The donor band of TiO2‑δ thin film is observed at ∼1.0 eV from the Fermi level (E F). The density-of-state at E F is higher in (004)-oriented TiO2‑δ thin film. The above results indicate that the oxygen vacancies can control by changing the P\\text{O2} of the oxygen radical.

  15. Influences of the Pd doping on the visible light photocatalytic activities of InVO4-TiO2 thin films

    Novel Pd/InVO4-TiO2 thin films with visible light photo activity were synthesized via a sol-gel method from the Pd and InVO2 co-doped TiO2 sol. The photocatalytic activities of Pd/InVO4-TiO2 thin films were investigated based on the oxidation decomposition of methyl orange in aqueous solution. The as-prepared samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and UV-vis absorption spectroscopy (UV-vis). The results indicate that the Pd/InVO4-TiO2 thin films are compact, uniform and consist of sphere nanoparticles with diameters about 80-100 nm. The UV-vis spectra show that the Pd/InVO4-TiO2 thin films extend the light absorption spectrum toward the visible region. XPS result reveal that doped Pd exist in the form of metallic palladium. The photocatalytic experiments demonstrate that Pd doping can effectively enhance the photo activities of InVO4-TiO2 thin films in decomposition of aqueous methyl orange under visible light irradiation. It has been confirmed that Pd/InVO4-TiO2 thin films could be excited by visible light (E 4 doped in the films. The photocatalytic mechanism of Pd/InVO4-TiO2 thin films is investigated in this paper

  16. TiO2 thin films self-assembled with a partly fluorinated surfactant template.

    Henderson, Mark J; Zimny, Kevin; Blin, Jean-Luc; Delorme, Nicolas; Bardeau, Jean-François; Gibaud, Alain

    2010-01-19

    New TiO(2) films have been self-assembled on solid substrate by dip-coating using TiCl(4) as the titanium source and the partly fluorinated surfactant F(CF(2))(8)C(2)H(4)(OC(2)H(4))(9)OH as the liquid crystal template. By control over the dip-withdrawal speed, film thicknesses from a minimum of 43 nm were produced with rms roughnesses of 0.5-0.7 nm. The films were characterized by X-ray reflectivity, grazing incidence small-angle X-ray scattering, atomic force microscopy, contact angle measurements, and Raman spectroscopy. Their GI-SAXS patterns are characteristic of a 2-D hexagonal structure in which tubular rods of the fluorinated surfactant are packed hexagonally and aligned parallel to the substrate. Reflectivity and contact angle measurements of the as-prepared film indicate that a low-density hydrophilic TiO(2) surface presents to the air. PMID:19754061

  17. Photocatalytic Oxidation of NOx with Porous TiO2 Nanometer Thin Film

    WANG Song-lin; TIAN Li-hong; ZHONG Jia-cheng; ZAN Ling

    2005-01-01

    A new kind of porous nano-TiO2 composite films was prepared on the glass substrate with the water glass as binders and the sodium fluorosilicate as solidifying reagent.The morphologies of the films were studied by scanning dectron microscope(SEM). The UV-Vis spectrophotometer was also used to investigate the absorption of the films. The gasphase photocatalytic oxidation of nitrogen oxides on the composite film was carried out in TiO2/UV system, and some important factors affecting the photocatalytic oxidation were also studied such as the catalyst concentration, vapor pressure and the presence of oxygen. The results showed the conversion of NOx reached 97. 5% after 2 h UV-irradiation. The final product of photo-oxidation was detected to be HNO3 by FTIR. The way of photocatalytic oxidation of NOx was possibly useful in the practical application.

  18. Structural and photodegradation behaviors of Fe3+-doping TiO2 thin films prepared by a sol–gel spin coating

    Highlights: • Pure and various Fe3+-doped TiO2 thin films have been successfully fabricated. • The phase of all thin films was single phase of anatase TiO2 when calcined at 823 K. • The crystallinity of TiO2 thin films decreased as Fe3+-doping increased. • The photodegradation of each sample increased as the irradiation time increased. • The photodegradation increased as Fe3+-doping increased at a fixed irradiation time. - Abstract: Pure and various Fe3+-doping TiO2 thin films have been successfully fabricated on glass substrate prepared by a sol–gel spin coating route. The structural and photodegradation behavior of these films after calcined at various temperatures for 1 h were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) spectrum and degradation of 1.0 × 10−5 M methylene blue solution. When all thin films after calcined at 823 K for 1 h, the crystalline phase are comprised only contained single phase of anatase TiO2. The crystallinity of various Fe3+-doping TiO2 thin films decreases with Fe3+-doping concentration increased. The PL intensity of all thin films also decreases with Fe3+-doping concentration increased. When all various Fe3+-doping TiO2 thin films after calcined at 823 K for 1 h, the photodegradation of each sample increases with irradiation time increased. Moreover, the photodegradation also increases with Fe3+-doping concentration increased when fixed at constant irradiation time

  19. Photocatalytic properties of dense plasma focus deposited nano phase TiO2 thin films: annealing effect

    Successful deposition of nano phase TiO2 thin films on silicon and glass substrates were achieved using the dense plasma focus (DPF) device. TiO2 thin films were prepared from a 99.95% pure titanium rod in oxygen–argon working gas mixture at ambient room temperature. The EDX and XPS results give the elemental composition of the films as Ti and O2. The XRD shows that amorphous films are predominant for low number of plasma focus shots. The SEM micrographs confirm the presence of nano-sized grains at smaller number of deposition shots or higher distance of deposition. Agglomeration was found to increase with the number of deposition shots. On annealing, the XRD diffractograms exhibit an increased in intensity and line width of the anatase (101) with the rutile phase R (110) emerging above 400°C. UV-Vis absorbance spectra for both as deposited and annealed films show a red shift for depositions from 20 plasma focus shots. The films showed visible light catalytic activity through decolouration of methylene blue solution. Visible light activity reached a maximum and decreased after 600 °C. Red shift and visible light catalysis can be explained in terms of the special feature effects of the plasma focus characteristic emissions. (author)

  20. Characteristics of N-doped TiO2 thin films grown on unheated glass substrate by inductively coupled plasma assisted dc reactive magnetron sputtering

    N-doped TiO2 thin films have been deposited on unheated glass substrates by an inductively coupled plasma (ICP) assisted direct current (dc) reactive magnetron sputtering. All films were produced in the metallic mode of sputtering in order to achieve a high deposition rate. The structures and properties of the N-doped TiO2 films were studied by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, field emission scanning electron microscopy and UV-Vis spectrophotometer. Experimental results show that we can obtain well crystallized N-doped anatase phase TiO2 thin films at low deposition temperature and at high deposition rate by using the ICP assisted dc reactive magnetron sputtering process. The doping of nitrogen into TiO2 lattices leads to a smooth shift of the absorption band toward visible light regions.

  1. Investigation of thin TiO 2 films cosputtered with Si species

    Hsu, Jin-Cherng; Lee, Cheng-Chung; Chen, Huang-Lu; Kuo, Chien-Cheng; Wang, Paul W.

    2009-02-01

    Titanium dioxide (TiO 2) films were fabricated by cosputtering titanium (Ti) target and SiO 2 or Si slice with ion-beam-sputtering deposition (IBSD) technique and were postannealed at 450 °C for 6 h. The variations of oxygen bonding, which included high-binding-energy oxygen (HBO), bridging oxygen (BO), low-binding-energy oxygen (LBO), and three chemical states of titanium (Ti 4+, Ti 3+ and Ti 2+) were analyzed by X-ray photoelectron spectroscopy (XPS). The enhancement of HBO and reduction of BO in O 1s spectra as functions of SiO 2 or Si amount in cosputtered film imply the formation of Si-O-Ti linkage. Corresponding increase of Ti 3+ in Ti 2p spectra further confirmed the property modification of the cosputtered film resulting from the variation of the chemical bonding. An observed correlation between the chemical structure and optical properties, refractive index and extinction coefficient, of the SiO 2 or Si cosputtered films demonstrated that the change of chemical bonding in the film results in the modification of optical properties. Furthermore, it was found that the optical properties of the cosputtered films were strongly depended on the cosputtering targets. In case of the Si cosputtered films both the refractive indices and extinction coefficients were reduced after postannealing, however, the opposite trend was observed in SiO 2 cosputtered films.

  2. Preparation and characterization of Fe2O3-TiO2 thin films on glass substrate for photocatalytic applications

    Fe2O3-TiO2 coatings were successfully prepared on glass slide substrates using sol-gel method for photocatalytic applications. The phase structure, thermal, microstructure and surface properties of the coatings were extensively characterized by using X-ray diffractometry (XRD), differential thermal analysis/thermograviometry (DTA/TG), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Their adhesion and absorbance properties were investigated by a scratch tester and UV-vis spectroscopy. Four different solutions were prepared by changing Fe/Ti molar ratios. Glass substrates were coated by solutions of Ti-alkoxide, Fe-chloride, glaciel acetic acid and isopropanol. The obtained gel films were dried at 300 deg. C for 10 min and subsequently heat-treated at 500 deg. C for 5 min in air. The oxide thin films were annealed at 600 deg. C for 60 min in air. The influence of Fe3+ concentration and number of layers on structure of the films was established. In addition, XRD results revealed that Fe2O3-TiO2 films composed of TiO2, Fe2Ti3O9, Ti3O5 and Fe3O4 phases. According to DTA/TG result, it was determined that endothermic and exothermic reactions were formed at temperatures between 80 and 650 deg. C due to solvent removal, combustion of carbon based materials and oxidation of Fe and Ti. SEM observations exhibited that the coating structure becomes more homogeneous depending on an increase of Fe/Ti molar ratios and thus a regular surface morphology forms with increasing Fe/Ti ratio. It was also seen that as the Fe/Ti ratio increases the surface roughness of the films increases. Critical adhesion force of thin films with Fe/Ti ratio of 0, 0.07, 0.18 and 0.73 were found to be 9, 25, 28 and 21 mN, respectively. The methylene blue solutions photocatalyzed by TiO2 based thin films shows characteristic absorption bands at 420 nm

  3. Angle-resolved photoemission spectroscopy for VO2 thin films grown on TiO2 (0 0 1) substrates

    We present the results of angle-resolved photoemission spectroscopy (ARPES) measurements of metallic VO2 thin films. The VO2 thin films have been grown on TiO2 (0 0 1) single crystal substrates using pulsed laser deposition. The films exhibit a first-order metal-insulator transition (MIT) at 305 K. In the ARPES spectra of the metallic phase for the films, the O 2p band shows highly dispersive feature in the binding energy range of 3-8 eV along the Γ-Z direction. The periodicity of the dispersive band is found to be 2.2 A-1 which is almost identical with the periodicity expected from the c-axis length of the VO2 thin films. The overall feature of the experimental band structure is similar to the band structure calculations, supporting that we have succeeded in observing the dispersive band of the O 2p state in the metallic VO2 thin film. The present work indicates that the ARPES measurements using epitaxial thin films are promising for determining the band structure of VO2.

  4. Dielectric relaxation and conduction mechanisms in sprayed TiO2 thin films as a function of the annealing temperature

    Juma, Albert; Acik, Ilona Oja; Mere, Arvo; Krunks, Malle

    2016-04-01

    The electrical properties of TiO2 thin films deposited by chemical spray pyrolysis onto Si substrates were investigated in the metal-oxide-semiconductor (MOS) configuration using current-voltage characteristics and impedance spectroscopy. The electrical properties were analyzed in relation to the changes in microstructure induced during annealing in air up to a temperature of 950 °C. Anatase to rutile transformation started after annealing at 800 °C, and at 950 °C, only the rutile phase was present. The dielectric relaxation strongly depended upon the microstructure of TiO2 with the dielectric constant for the anatase phase between 45 and 50 and that for the rutile phase 123. Leakage current was reduced by three orders of magnitude after annealing at 700 °C due to the densification of the TiO2 film. A double-logarithmic plot of the current-voltage characteristics showed a linear relationship below 0.12 V consistent with Ohmic conduction, while space-charge-limited conduction mechanism as described by Child's law dominated for bias voltages above 0.12 V.

  5. Highly oriented and physical properties of sprayed anatase Sn-doped TiO2 thin films with an enhanced antibacterial activity

    Dhanapandian, S.; Arunachalam, A.; Manoharan, C.

    2016-03-01

    Pristine TiO2 and Sn-doped TiO2 thin films with different Sn doping levels (2, 4, 6 and 8 at.%) were deposited by employing a simplified spray pyrolysis technique. The XRD pattern of the films confirmed tetragonal structure with the polycrystalline nature. The films exhibited a pure anatase titanium dioxide (TiO2) with a strong orientation along (101) plane. The scanning electron microscopy image of 6 at.% Sn-doped TiO2 thin film depicted nanosized grains with porous nature. The atomic force microscopy study had shown the columnar arrangement of grains with the increase in particle size and surface roughness for 6 at.% Sn-doped TiO2 thin films. The optical transmittance was increased with the decrease in the optical energy band gap. The optical constants such as extinction coefficient and refractive index were determined. The intensity of the photoluminescence emission was observed at 398 nm for doped films. The resistivity decreased with the increasing carrier concentration and Hall mobility. The incorporation of Sn into TiO2 matrix yielded a well-pronounced antibacterial activity for Bacillus subtilis.

  6. Controllable preparation of nanosized TiO2 thin film and relationship between structure of film and its photocatalytic activity

    魏刚; 张元晶; 熊蓉春

    2003-01-01

    TiO2 nano-crystalline film and fixed bed photocatalytic reactor were prepared by the sol-gel process using tetrabutylorthotitanate as a precursor and glass tube as the substrate. XRD, AFM, SEM and thickness analysis results indicate that the preparation of nano-crystalline film can be controlled by optimizing experiment process. Under the optimized process, the phase of TiO2 in film is anatase, and the grain size is 3-4 nm. The size of particles, which is about 20-80 nm, can be controlled. The thickness of monolayer film is in nanometer grade. The thickness and particles size in films growing on nanometer film can also be controlled in nanometer grade. As a result, the crack of film can be effectively avoided. Rhodamine B degradation results using UV-Vis spectrophotometer show that the activity of nano-crystalline film in the photocatalytic reactor has a good relation with the diameter of TiO2 particles, that is, the film shows high activity when the size is 20-30 nm and greatly reduced when the size is above 60 nm. The activity of film does not decrease with the increase of film thickness, and this result indicates that nano-crystalline film has no ill influence on the transmissivity of ultraviolet light.

  7. The Influence of Various Deposition Techniques on the Structural and Photoelectrochemical Properties of the thin TiO2 Films

    Morozová, Magdalena; Klusoň, Petr; Dzik, P.; Veselý, M.; Baudys, M.; Krýsa, J.; Šolcová, Olga

    Prague: KANAG -TISK, 2014 - (Krýsa, J.; Klusoň, P.), s. 14-15 ISBN 978-80-7080-886-3. [Czech-Austrian Workshop: New Trends in Photo and Electro Catalysis /6./. Hnanice (CZ), 02.12.2013-04.12.2013] R&D Projects: GA TA ČR TA01020804 Grant ostatní: GA ČR(CZ) GP104/09/P165; GA ČR(CZ) GAP108/12/2104 Institutional support: RVO:67985858 Keywords : thin films * nanostructured electrode material * TiO2 layers Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  8. Growth and characterization of nitrogen-doped TiO2 thin films prepared by reactive pulsed laser deposition

    Nitrogen-doped titanium dioxide (TiO2) thin films were grown on (001) SiO2 substrates by reactive pulsed laser deposition. A KrF* excimer laser source (λ = 248 nm, τFWHM ≅ 10 ns, ν = 10 Hz) was used for the irradiations of pressed powder targets composed by both anatase and rutile phase TiO2. The experiments were performed in a controlled reactive atmosphere consisting of oxygen or mixtures of oxygen and nitrogen gases. The obtained thin film crystal structure was investigated by X-ray diffraction, while their chemical composition as well as chemical bonding states between the elements were studied by X-ray photoelectron spectroscopy. An interrelation was found between nitrogen concentration, crystalline structure, bonding states between the elements, and the formation of titanium oxinitride compounds. Moreover, as a result of the nitrogen incorporation in the films a continuous red-shift of the optical absorption edge accompanied by absorption in the visible spectral range between 400 and 500 nm wavelength was observed.

  9. Optical parameters induced by phase transformation in RF magnetron sputtered TiO2 nanostructured thin films

    Prabitha B.Nair; V.B.Justinvictor; Georgi P.Daniel; K.Joy; K.C.James Raju; David Devraj Kumar; P.V.Thomas

    2014-01-01

    Pure TiO2 thin films were deposited onto quartz substrates using a ceramic TiO2 target at an elevated substrate temperature of 573 K by RF magnetron sputtering, and an analysis of structural, optical and photoluminescence characteristics of the films upon phase transformation is reported in this paper. Structural investigations using X-ray diffraction revealed that the as-deposited film was amorphous in nature. Thermal annealing for 2 h at 873 K in air resulted in the formation of anatase phase, and a phase transformation to rutile was observed at 1073 K. An increase in grain size and an improvement in crystallinity were also observed on annealing. Rod-like rutile crystallites were observed in the SEM images of the film annealed at 1273 K. As-deposited films and films annealed up to 1073 K were highly transparent in the visible region with a transparency 4 80%. Optical band gap of the films decreased upon thermal annealing which is attributed to phase transformation from amorphous to anatase and then to rutile. Optical parameters such as refractive index, optical conductivity and optical dielectric constant increased with increase in annealing temperature. Since rutile is the optically active phase, the superior refractive index of the film annealed at 1073 K along with its high transparency in visible region suggests the application of this film in antireflective coatings. Photoluminescence emission of maximum intensity was observed for the film annealed at 873 K, which exhibits anatase phase. Intense blue emission observed in this film makes it suitable for use in optoelectronic display devices.

  10. Photocatalytic activity of Al2O3-doped TiO2 thin films activated with visible light on the bacteria Escherichia coli

    Al2O3-doped TiO2 thin films were prepared by combining electrophoretic deposition (EPD) with sputtering. A Corning* glass was used as a substrate, in which a titanium film was deposited by sputtering. Then, a precursor sol was prepared with Ti(n-OBu)4 and Al(s-OBu)3 and used as the medium for EPD. Next, the thin films were sintered and, finally, characterised by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). Several cultures of Escherichia coli, strain XL1-Blue, were prepared. Nine experiments were carried out. In three of them, an inoculum (a low amount of a product that contains bacteria) was prepared without a film; in the other six Al2O3-doped TiO2 film-coated glass substrates were irradiated with visible light before they were introduced in the inoculum. The SEM and EDS results showed that TiO2-Al2O3 films were obtained, covering all the glass substrate and with uniform size of particles forming them, and that the aluminium was distributed uniformly on the film. XRD results showed that rutile phase was obtained. By TEM, the structure of TiO2 was demonstrated. Al2O3-doped TiO2 thin films were successful at eliminating E. coli.

  11. Synergistic effect on the photocatalytic degradation of 2-chlorophenol using TiO2 thin films doped with some transition metals in water

    The metalorganic chemical vapor deposition (MOCVD) method has been used to prepare TiO2 thin films for the degradation of hazardous organic compounds, such as 2-chlorophenol (2-CP). The effect of supporting materials and metal doping on the photocatalytic activity of TiO2 thin films also has been studied. TiO2 thin films were coated onto various supporting materials, including stainless steel cloth(SS), quartz glass tube(QGT), and silica gel (SG). Transition metals,such as Pd(II), Pt(IV), Nd(III) and Fe(III), were doped onto TiO2 thin film. The results indicate that Nd(III) doping improves the photodegradation of 2-CP. Among all supporting materials studied, SS(37 μm) appears to be the best support. An optimal amount of doping material at 1.0 percent (w/w) of TiO2-substrate thin film gives the best photodegradation 2-CP

  12. Strategies to prepare TiO2 thin films, doped with transition metal ions, that exhibit specific physicochemical properties to support osteoblast cell adhesion and proliferation

    Metal ion doped titanium oxide (TiO2) thin films, as bioactive coatings on metal or other implantable materials, can be used as surfaces for studying the cell biological properties of osteogenic and other cell types. Bulk crystallite phase distribution and surface carbon–oxygen constitution of thin films, play an important role in determining the biological responses of cells that come in their contact. Here we present a strategy to control the polarity of atomic interactions between the dopant metal and TiO2 molecules and obtain surfaces with smaller crystallite phases and optimal surface carbon–oxygen composition to support the maximum proliferation and adhesion of osteoblast cells. Our results suggest that surfaces, in which atomic interactions between the dopant metals and TiO2 were less polar, could support better adhesion, spreading and proliferation of cells. - Highlights: • Electrochemical properties of dopants control the nature of TiO2 thin films. • A model explains the correlation of dopant properties and behaviour of TiO2 films. • Dopants with less polar interaction with TiO2 exhibit better biological activity

  13. Investigation of photocatalytic activity of TiO2/WO3 bilayered thin films with various amounts of WO3 exposed surface

    Transparent WO3/TiO2 bilayered thin films were deposited on glass substrates by facing target sputtering technique with different amounts of WO3 exposed surface (0%, 30%, 50%, 80%, and 100%) to study the separate role of WO3 and TiO2 in the photocatalytic activity of the composite system. The crystallographic and optical properties of WO3 and the TiO2 layers were investigated in detail. The photocatalytic activity was evaluated by the measurement of decomposition of methanol in gas phase under visible light irradiation with very little ultraviolet content. The rate of decomposition of gaseous methanol largely depends on the ratio of WO3/TiO2 exposed surface. The decomposition efficiency of WO3/TiO2 films increased with an increase in TiO2 exposed surface and the sample with 70%TiO2 exposed area showed the highest efficiency. The surface morphology of all the layers was investigated by the measurement of field emission scanning electron microscope and atomic force microscope. The variation in photocatalytic activity has been tried to be explained on the basis of methanol-photodecomposition mechanism and the intrinsic properties of WO3 and TiO2 semiconductor.

  14. Compositional and Structural Properties of TiO2-xNx Thin Films Deposited by Radio-Frequency Magnetron Sputtering

    JING Shi-Wei; LIU Yi-Chun; LIANG Yu; MA Jian-Gang; LU You-Ming; SHEN De-Zhen; ZHANG Ji-Ying; FAN Xi-Wu; MU Ri-Xiang

    2006-01-01

    @@ TiO2-xNx thin films are deposited onto Si(100) and quartz substrates by a rf magnetron sputtering method using a titanium metal disc as a target in Ar, N2, and O2 atmospheres. The substrate temperature is kept at 300°C. The O2 and Ar gas flow rates are kept to be constants and the N gas flow rate is varied. TiO2-xNx films with different N contents are characterized by x-ray diffraction and x-ray photoelectron spectroscopy. The results indicate that the TiO2-xNx thin films can be obtained at 13% N and 15% N contents in the film, and the films with mixed TiO2 and TiN crystal can be obtained at 13% N and 15% N contents in the film. In terms of the results of x-ray photoelectron spectroscopy, N 1s of β-N (396 eV) is the main component in the TiO2-xNx thin films.

  15. A Micro Oxygen Sensor Based on a Nano Sol-Gel TiO2 Thin Film

    Hairong Wang

    2014-09-01

    Full Text Available An oxygen gas microsensor based on nanostructured sol-gel TiO2 thin films with a buried Pd layer was developed on a silicon substrate. The nanostructured titania thin films for O2 sensors were prepared by the sol-gel process and became anatase after heat treatment. A sandwich TiO2 square board with an area of 350 μm × 350 μm was defined by both wet etching and dry etching processes and the wet one was applied in the final process due to its advantages of easy control for the final structure. A pair of 150 nm Pt micro interdigitated electrodes with 50 nm Ti buffer layer was fabricated on the board by a lift-off process. The sensor chip was tested in a furnace with changing the O2 concentration from 1.0% to 20% by monitoring its electrical resistance. Results showed that after several testing cycles the sensor’s output becomes stable, and its sensitivity is 0.054 with deviation 2.65 × 10−4 and hysteresis is 8.5%. Due to its simple fabrication process, the sensor has potential for application in environmental monitoring, where lower power consumption and small size are required.

  16. Enhanced photoelectrochemical properties of F-containing TiO2 sphere thin film induced by its novel hierarchical structure

    The novel nanostructured F-containing TiO2 (F-TiO2) sphere was directly synthesized on the surface of Ti foil in the solution of NH4F and HCl by one-step hydrothermal approach under low-temperature condition. The samples were characterized respectively by means of field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results showed that the F-TiO2 sphere was hierarchical structure, which composed of porous octahedron crystals with one truncated cone, leading to a football-like morphology. XPS results indicated that F- anions were just physically adsorbed on the surface of TiO2 microspheres. The studies on the optical properties of the F-TiO2 were carried out by UV-vis light absorption spectrum. The surface fluorination of the spheres, the unique nanostructure induced accessible macropores or mesopores, and the increased light-harvesting abilities were crucial for the high photoelectrochemical activity of the synthesized F-TiO2 sphere for water-splitting. The photocurrent density of the F-TiO2 sphere thin film was more than two times than that of the P25 thin film. Meanwhile, a formation mechanism was briefly proposed. This approach could provide a facile method to synthesize F-TiO2 microsphere with a special morphology and hierarchical structure in large scale.

  17. Crystal Structure And Optical Properties Of TiO2 Thin Films Prepared By Reactive RF Magnetron Sputtering

    Goto S.

    2015-06-01

    Full Text Available In sputtering deposition process of TiO2, metal Ti or sintered TiO2 target is used as deposition source. In this study, we have compared the characteristic of target materials. When TiO2 target was used, stoichiometric TiO2 films was deposited under the Ar atmosphere containing 1.0% of oxygen. The highest sputtering rate under this atmosphere was 3.9nm/min at 3.4W/cm2. But, sintered TiO2 target is fragile and cannot endure higher density of input power than 3.4W/cm2. On the other hand, Ti target needs higher oxygen concentration (8% in sputtering gas atmosphere for obtaining rutile/anatase. Even though Ti target can be input twice power density of 7.9W/cm2, the highest deposition rate for Ti target was 1.4/nm, which was ~35% of the highest rate for TiO2 target. Then we have study out the composite target consisting of Ti plate and TiO2 chips. Using the composite target, stoichiometric TiO2 films were prepared in the rate of 9.6nm/min at 6.8 W/cm2 under the atmosphere of Ar/2.5%O2. Furthermore, we have found that the TiO2 films obtained from the composite target consisted of about 100% anatase, whereas TiO2 films obtained from other target have rutile dominant structure. The optical band gap energy of the film is determined by using the Tauc plot. The calculated band gap energies for the films deposited by Ti target and composite target were 2.95 and 3.24eV, which are equivalent to that of rutile and anatase structure, respectively.

  18. Charge Separation in TiO2/BDD Heterojunction Thin Film for Enhanced Photoelectrochemical Performance.

    Terashima, Chiaki; Hishinuma, Ryota; Roy, Nitish; Sugiyama, Yuki; Latthe, Sanjay S; Nakata, Kazuya; Kondo, Takeshi; Yuasa, Makoto; Fujishima, Akira

    2016-01-27

    Semiconductor photocatalysis driven by electron/hole has begun a new era in the field of solar energy conversion and storage. Here we report the fabrication and optimization of TiO2/BDD p-n heterojunction photoelectrode using p-type boron doped diamond (BDD) and n-type TiO2 which shows enhanced photoelectrochemical activity. A p-type BDD was first deposited on Si substrate by microwave plasma chemical vapor deposition (MPCVD) method and then n-type TiO2 was sputter coated on top of BDD grains for different durations. The microstructural studies reveal a uniform disposition of anatase TiO2 and its thickness can be tuned by varying the sputtering time. The formation of p-n heterojunction was confirmed through I-V measurement. A remarkable rectification property of 63773 at 5 V with very small leakage current indicates achieving a superior, uniform and precise p-n junction at TiO2 sputtering time of 90 min. This suitably formed p-n heterojunction electrode is found to show 1.6 fold higher photoelectrochemical activity than bare n-type TiO2 electrode at an applied potential of +1.5 V vs SHE. The enhanced photoelectrochemical performance of this TiO2/BDD electrode is ascribed to the injection of hole from p-type BDD to n-type TiO2, which increases carrier separation and thereby enhances the photoelectrochemical performance. PMID:26756353

  19. Optical and morphological characterization of photocatalytic TiO2 thin films doped with silver

    Silver-doped titanium dioxide thin films were deposited on glass substrates by the sol-gel process. Undoped films and films doped with 1 and 3 mol% Ag were annealed at 100 or 500 oC. The optical and morphological properties of the films were analyzed by optical absorption spectroscopy and scanning electron microscopy. Additionally, the films were evaluated for their ability to degrade methylene blue. It was found that the photocatalytic activity is barely sensitive to silver doping for films annealed at 100 oC, whereas the effect of silver resulted in enhanced photocatalytic activity for films annealed at 500 oC. For the latter annealing temperature, the photocatalytic activity increased with increasing Ag doping concentration.

  20. Studies on the performance of TiO2 thin films as protective layer to chlorophyll in Ocimum tenuiflorum L from UV radiation

    Malliga, P.; Selvi, B. Karunai; Pandiarajan, J.; Prithivikumaran, N.; Neyvasagam, K.

    2015-06-01

    Thin films of TiO2 were prepared on glass substrates using sol-gel dip coating technique. The films with 10 coatings were prepared and annealed at temperatures 350°C, 450˚C and 550˚C for 1 hour in muffle furnace. The annealed films were characterized by X - Ray diffraction (XRD), UV - Visible, AFM, Field Effect Scanning Electron Microscopy (FESEM) and EDAX studies. Chlorophyll has many health benefits due to its structural similarity to human blood and its good chelating ability. It has antimutagenic and anticarcinogenic properties. UV light impairs photosynthesis and reduces size, productivity, and quality in many of the crop plant species. Increased exposure of UV light reduces chlorophyll contents a, b and total content in plants. Titanium Dioxide (TiO2) is a wide band gap semiconductor and efficient light harvester. TiO2 has strong UltraViolet (UV) light absorbing capability. Here, we have studied the performance of TiO2 thin films as a protective layer to the chlorophyll contents present in medicinal plant, tulsi (Ocimum tenuiflorum L) from UV radiation. The study reveals that crystallite size increases, transmittance decreases and chlorophyll contents increases with increase in annealing temperature. This study showed that TiO2 thin films are good absorber of UV light and protect the chlorophyll contents a, b and total content in medicinal plants.

  1. Studies on the performance of TiO2 thin films as protective layer to chlorophyll in Ocimum tenuiflorum L from UV radiation

    Thin films of TiO2 were prepared on glass substrates using sol-gel dip coating technique. The films with 10 coatings were prepared and annealed at temperatures 350°C, 450°C and 550°C for 1 hour in muffle furnace. The annealed films were characterized by X – Ray diffraction (XRD), UV – Visible, AFM, Field Effect Scanning Electron Microscopy (FESEM) and EDAX studies. Chlorophyll has many health benefits due to its structural similarity to human blood and its good chelating ability. It has antimutagenic and anticarcinogenic properties. UV light impairs photosynthesis and reduces size, productivity, and quality in many of the crop plant species. Increased exposure of UV light reduces chlorophyll contents a, b and total content in plants. Titanium Dioxide (TiO2) is a wide band gap semiconductor and efficient light harvester. TiO2 has strong UltraViolet (UV) light absorbing capability. Here, we have studied the performance of TiO2 thin films as a protective layer to the chlorophyll contents present in medicinal plant, tulsi (Ocimum tenuiflorum L) from UV radiation. The study reveals that crystallite size increases, transmittance decreases and chlorophyll contents increases with increase in annealing temperature. This study showed that TiO2 thin films are good absorber of UV light and protect the chlorophyll contents a, b and total content in medicinal plants

  2. Physical properties of Zn doped TiO2 thin films with spray pyrolysis technique and its effects in antibacterial activity.

    Arunachalam, A; Dhanapandian, S; Manoharan, C; Sivakumar, G

    2015-03-01

    Zinc doped Titanium dioxide (TiO2: Zn) thin films were deposited onto glass substrates by the spray pyrolysis technique with the substrate temperature 450°C. The structural, optical, photoluminescence (PL) properties and morphological studies were investigated for the films deposited with various doping concentration (0, 2, 4, 6 and 8at.%) of zinc. The results of X-ray diffraction (XRD) had shown the presence of anatase peak with a strong orientation along (101) plane at 8at.% of Zn-doped TiO2 film. Scanning electron microscopy (SEM) study showed the uniform distribution of grains with porous nature. Atomic force microscopy (AFM) observations indicated the tetragonal shape at 8at.% of Zn-doped TiO2 with the particle size and decrease in surface roughness. The emission at 398nm was observed at the 8at.% of Zn-doped TiO2 thin film. The carrier concentration and Hall mobility was increased with doping. The antibacterial activity was highly yielded for the Zn-doped TiO2 thin films. PMID:25479105

  3. Thickness-dependent electron transport performance of mesoporous TiO2 thin film for dye-sensitized solar cells

    Anatase titania (TiO2) nanocrystals with an average size of 12 nm were synthesized by combining sol–gel method and hydrothermal crystallization technology. Mesoporous TiO2 thin film electrodes (MTTFEs) were prepared by variations in layer of screen-printed TiO2 nanocrystals pastes, and dye-sensitized solar cells (DSCs) based on different thickness of MTTFEs were fabricated with dye C106. Under the irradiation of 100 mW cm−2 air mass 1.5 global (AM1.5G) sunlight, the short-circuit photocurrent density (Jsc) and overall conversion efficiency (η) was improved when the thickness of MTTFEs increased from 2.1 μm to 9.8 μm, and obvious decreases of the Jsc and η were found when the film thickness was further increased over 9.8 μm. The kinetic parameters of electron transport were investigated by the transient photoelectrical and electrical impedance measurements, and then the influence of MTTFEs thickness on electron transport performance in DSCs were further discussed. The results showed that the density of states (DOS) and recombination rate (Kr) increased with the MTTFEs thickness increasing. Furthermore, when the thickness of MTTFEs was in the range of 2.1–9.8 μm, the electron lifetime (τn), the electron diffusion coefficient (Dn), and the electron diffusion length (Ln) of devices increased, but these parameters decreased gradually with the further increased thickness of MTTFEs, which influenced the electronic transport performance of DSCs

  4. A Novel Multi-Tube Photoreactor with UV Light and Immobilized TiO2 Thin Film for Water Treatment

    谢一兵; 沈迅伟; 等

    2003-01-01

    A novel multi-tube photoreactor with 0.0188m3 valid reaction volume was constructed in pilot-scale.This rectangular reactor consisted of 13 regularly distributed silica glass tubes coating with TiO2 thin film photocatalyst.Total active area of TiO2 thin is 0.3916m2,The ratio of surface area to volume achieves 20.8m-1 .Photocatalytic experiment of phenol red demonstrates that the apparent reaction rate constant(k) is 0.07465h-1 and 0.16502h-1 for reaction system with and without micro-bubbles mixing.The corresponding apparent quantum efficiency( Φa) is 8.1771×10-7g·J-1 and 4.9036×10-7g·J-1,rspectively,COD value of reactant could decrease to 17mg·L-1 and high performance liquid chromatography(HPLC) only shows two absorption peaks in 24h photocatalytic process time,so this photoreactor has good photomineralization effect.Experimental results reveal that photocatalytic destruction of organics is possible by using the multi-tube photoreactor.

  5. Nanoindentation of nanocolumnar TiO2 thin films with single and stacked zig-zag layers

    Jiménez-Piqué, E. [Material Science and Metallurgical Engineering Department and Center for Research in Nanoengineering, UniversistatPolitècnica de Catalunya, Avda. Diagonal 647 (ETSEIB), 08028 Barcelona (Spain); González-García, L.; Rico, V.J.; González-Elipe, A.R. [Instituto de Ciencia de Materiales de Sevilla (CSIC-Univ. Sevilla), Avda. Américo Vespucio 49, 41092 Sevilla (Spain)

    2014-01-01

    This paper reports a systematic analysis of the mechanical properties of nanocolumnar TiO{sub 2} thin films prepared by evaporation at a glancing geometry. A systematic study of the mechanical properties is carried out by comparing the hardness and the Young's modulus determined by nanoindentation for thin films prepared at different deposition angles and characterized by a tilted nanocolumnar structure and others where the nanocolumns are perpendicular to the substrate or are arranged as zig-zag stacked layers. A correlation between mechanical properties and glazing angle geometry is proposed. Differences in the results are discussed in view of the cross section images obtained by focused ion beam and of the deformed areas. Zig-zagged layers present lower values of hardness and Young's modulus due to the collapse of the angles of the columns, but at the same time this configuration impedes the appearance of fracture or delamination, as observed for tilted columns. - Highlights: • TiO2 thin films with tilted columns and zigzag microstructures were deposited. • Nanoindentation was performed on the different films. • Deformation mechanisms were identified with focused ion beam cross sections. • Mechanical response was rationalized in terms of depositing parameters.

  6. Radio Frequency Magnetron Sputtering Deposition of TiO2 Thin Films and Their Perovskite Solar Cell Applications

    Chen, Cong; Cheng, Yu; Dai, Qilin; Song, Hongwei

    2015-12-01

    In this work, we report a physical deposition based, compact (cp) layer synthesis for planar heterojunction perovskite solar cells. Typical solution-based synthesis of cp layer for perovskite solar cells involves low-quality of thin films, high-temperature annealing, non-flexible devices, limitation of large-scale production and that the effects of the cp layer on carrier transport have not been fully understood. In this research, using radio frequency magnetron sputtering (RFMS), TiO2 cp layers were fabricated and the thickness could be controlled by deposition time; CH3NH3PbI3 films were prepared by evaporation & immersion (E & I) method, in which PbI2 films made by thermal evaporation technique were immersed in CH3NH3I solution. The devices exhibit power conversion efficiency (PCE) of 12.1% and the photovoltaic performance can maintain 77% of its initial PCE after 1440 h. The method developed in this study has the capability of fabricating large active area devices (40 × 40 mm2) showing a promising PCE of 4.8%. Low temperature and flexible devices were realized and a PCE of 8.9% was obtained on the PET/ITO substrates. These approaches could be used in thin film based solar cells which require high-quality films leading to reduced fabrication cost and improved device performance.

  7. Influence of O2 partial pressure on the growth of nanostructured anatase phase TiO2 thin films prepared by DC reactive magnetron sputtering

    Research highlights: → Growth of crystalline anatase TiO2 can be controlled by % O2 and sputtering power. → Agglomeration of TiO2 nano-sized grains is observed and rises with decrease in % O2. → Nano-sized grains promote the formation of porous TiO2 films. → Deposition parameters have great influence on the optical properties of TiO2 films. - Abstract: Nanostructured titanium dioxide (TiO2) thin films were deposited on unheated glass substrates by DC reactive magnetron sputtering. The influence of the oxygen percentage in the discharge and the sputtering power (P) on the phase composition, crystallinity, surface morphology and optical properties of the films was investigated. The structure of the as-sputtered TiO2 films prepared in different oxygen concentrations for P = 500 W and 1000 W varies from amorphous to crystalline. X-ray diffraction revealed that, excluding the lowest oxygen concentration (1% O2), all annealed TiO2 thin films at 400 deg. C/4 h have an anatase crystal structure and the crystallinity decreases with the oxygen percentage. However, for 5 and 10% O2, the films are textured with the (1 0 1) crystal direction normal to the substrate surface and for O2 ≥ 15% the films have the preferred orientation (0 0 4), which is accounted for different surface energies associated with different planes. Field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) evidence distinct modifications in the morphology of the thin films which are corroborated with the crystallite sizes estimated from the typical diffraction peaks. Agglomeration of smaller TiO2 nano-sized grains to form bigger sized particulates is observed and enhanced by the decrease in oxygen content. With the variation in oxygen concentration, the optical properties (refractive index and optical band gap) of TiO2 films also change strongly being dependent on crystallinity, crystallite size and oxygen vacancies.

  8. Synthesis of nanocrystalline TiO2 thin films by liquid phase deposition technique and its application for photocatalytic degradation studies

    Noor Shahina Begum; H M Farveez Ahmed

    2008-02-01

    A transparent, high purity titanium dioxide thin film composed of densely packed nanometer sized grains has been successfully deposited on a glass substrate at 30°C from an aqueous solution of TiO2–HF with the addition of boric acid as a scavenger by liquid phase deposition technique. From X-ray diffraction measurement, the deposited film was found to be amorphous and turns crystalline at 500°C. The deposited film showed excellent adherence to the substrate and was characterized by homogeneous flat surface. TiO2 thin films can be used as a photocatalyst to clean up organohalides, a class of compound in pesticides that pollute the ground water. Photocatalytic degradation experiments show that indanthrene golden orange dye undergoes degradation efficiently in presence of TiO2 thin films by exposing its aqueous solution to ultraviolet light. The suitable surface structure and porosity increases the photocatalytic activity. It was also observed that hemin doped TiO2 thin films break up organohalides at a surprisingly high rate under visible light.

  9. Preparation and photo-induced superhydrophilicity of composite TiO2-SiO2-In2O3 thin film

    In this work, TiO2-SiO2-In2O3 composite thin films on glass substrates were prepared by the sol-gel dip coating process. X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF) and X-ray photoelectron spectroscopy (XPS) were used to evaluate the structural and chemical properties of the films. UV-vis spectrophotometer was used to measure the transmittance spectra of thin films. The water contact angle (WCA) of thin films during UV/vis irradiation and storage in a dark place was measured by a contact angle analyzer. The results indicated that fabrication of composite film has a significant effect on transmittance and superhydrophilicity of TiO2 films.

  10. Effect of sputtering pressure and post-annealing on hydrophilicity of TiO2 thin films deposited by reactive magnetron sputtering

    A series of TiO2 thin films was deposited onto glass substrates without intentional heating or biasing by magnetron sputtering of a titanium target using Ar/O2 reactive mixtures over a broad range of total sputtering pressures from 0.12 Pa to 2.24 Pa. Each of the film types was deposited by the threshold poisoned mode at a specific given oxygen flow rate monitored in-situ by optical emission spectroscopy. Both the sputtering pressure and thermal annealing are the key factors for the TiO2 films to yield fast-response superhydrophilicity with a water contact angle of 5o. The mechanism of superhydrophilicity for the TiO2 films deposited by high-pressure sputtering will be discussed based on empirical studies of X-ray diffractometry, high-resolution scanning microscopy and atomic force spectroscopy.

  11. Photocatalytic removal of hazardous Ponceau S dye using Nano structured Ni-doped TiO2 thin film prepared by chemical method

    Marathe, Sunil D.; Shrivastava, Vinod S.

    2015-02-01

    Many attempts have been made by researchers for the removal of various dyes using nano structured Ni-doped TiO2; however, removal of `hazardous Ponceau S dye' using nano structured Ni-doped TiO2 has been not studied yet. In the present work, environmental application of Nano structured Ni doped TiO2 has been studied. Nano structured Ni-doped TiO2 thin films were deposited by the chemical method on a glass substrate. The prepared thin film was characterized by XRD, SEM, and EDX. The crystal size calculated from XRD is about 26.2 nm. The SEM analysis reveals nano spherical morphology of average particle size about 92 nm. The optical analysis was carried by using UV-visible spectroscopy. The band gap estimated from absorbance spectra for thin film was around 3.5 eV, making suitable Ni-doped TiO2 for photocatalytic removal of hazardous Ponceau S dye. In photocatalytic application different parameters like dye concentration, contact time, pH, UV light and sunlight were optimized for the removal of Ponceau S dye, respectively. The change in chemical oxygen demand after photo catalytic treatment was also studied.

  12. Initial stages of TiO 2 thin films MOCVD growth studied by in situ surface analyses

    Brevet, A.; Peterlé, P. M.; Imhoff, L.; Marco de Lucas, M. C.; Bourgeois, S.

    2005-02-01

    In situ chemical surface analyses using X-ray photoelectron spectroscopy (XPS) were performed to understand the initial stages of TiO 2 thin-film MOCVD growth. Deposits on Si (1 0 0), a few nanometres thick, were obtained at a fixed temperature of 650 °C and for two different pressures, 2.9 and 0.05 mbar, using titanium tetraisopropoxide (TTIP) as precursor. Pressure lowering led to a higher deposit growth rate. Reduction of titanium with respect to stoichiometric titanium dioxide and oxidation of the wet-cleaned silicon substrate are observed from decomposition of the Ti 2p and Si 2p peaks. The formation of a TiSi xO y mixed oxide is also pointed out and confirmed by the presence of a characteristic component in the O 1 s peak.

  13. Room temperature deposition of highly dense TiO2 thin films by filtered cathodic vacuum arc

    Guillén, E.; Heras, I.; Rincón Llorente, G.; Lungwitz, F.; Alcon-Camas, M.; Escobar-Galindo, R.

    2015-08-01

    A systematic study of TiO2 films deposited by dc filtered cathodic vacuum arc (FCVA) was carried out by varying the deposition parameters in a reactive oxygen atmosphere. The influence of the oxygen partial pressure on film properties is analyzed. Composition was obtained by Rutherford backscattering spectroscopy (RBS) measurements, which also allow us to obtain the density of the films. Morphology of the samples was studied by scanning electron microscopy (SEM) and their optical properties by ellipsometry. Transparent, very dense and stoichiometric TiO2 films were obtained by FCVA at room temperature.

  14. The effect of aeration and solar intensity power on photocatalytic degradation of textile industrial wastewater using TiO2 thin film

    Solar photo catalytic degradation of the textile industry wastewater using TiO2 thin films was studied. This experiment was performed to investigate the effect of aeration and solar intensity power on decreasing of Chemical Oxygen Demand (COD). A serpentine flow photo catalytic reactor was developed for this purpose. TiO2 thin films photo catalyst supported on the stainless steel 304 substrates were prepared using sol-gel dip coating method. The results of thin films were characterized by Scanning Electron Microscopy (SEM) and X-Ray Diffractometer (XRD). XRD result showed that the prepared thin films gave the anatase crystallite formation whilst SEM demonstrated the macro pores were formed. Finally, the aeration and solar intensity power factors are considered to be responsible for the photo catalytic degradation. (Author)

  15. Interdigitated electrode (IDE) based on titanium dioxide (TiO2) thin films for biosensor application

    Nordin, N.; Hashim, U.; Azizah, N.

    2016-07-01

    Sensor is the device that can detect and produce output or response that comes from any input from the physical environment. In this study, sensor is developed by simple photolithography process to create a small IDE device. The device is coated with Titanium Dioxide (TiO2) to give the positive result in detection. The result shows the device with coating stabilized at 2.46×10-10 compare to device without TiO2 which only at 2.24×10-10. IDE device is reusable and can use many times for different kind of detection.

  16. Photocatalytic Activity of TiO2 Thin Films Obtained by the Sputtering RF in Wastewater

    Cardona Bedoya, Jairo Armando; Sanchez Velandia, Wilmer Asmed; Delgado Rosero, Miguel Iban; Florido Cuellar, Alex Enrique; Zelaya Angel, Orlando; Mendoza Alvarez, Julio G.

    2011-03-01

    The photocatalytic activity of Ti O2 thin films in wastewater, under an UV irradiation, is studied. The films were prepared on corning glass substrates by the sputtering RF technique. We present evidence on the photocatalytic degradation, carried out by advanced oxidation processes (AOPs) in domestic wastewater pretreated with UASB (upflow anaerobic sludge blanket) reactors. Ti O2 films were illuminated with ultraviolet light during a time of 4 hours (λ ≅ 264 nm). We could see the effect of degraded operation in the absorbance measurement using UV-VIS spectrophotometry. The results show an increased rate of degradation of the wastewater by 30% compared to the values reflected biologically treated wastewater by anaerobic reactors.

  17. Combining a molecular modelling approach with direct current and high power impulse magnetron sputtering to develop new TiO2 thin films for antifouling applications

    Guillot, Jérôme; Lecoq, Elodie; Duday, David; Puhakka, Eini; Riihimäki, Markus; Keiski, Riitta; Chemin, Jean-Baptiste; Choquet, Patrick

    2015-04-01

    The accumulation of crystallization deposits at the surface of heat exchangers results in the increase of the heat transfer resistance and a drastic loss of efficiency. Coating surfaces with a thin film can limit the scale-surface adhesion force and thus the fouling process. This study compares the efficiency of TiO2 layers exhibiting various crystalline planes and microstructures to reduce the kinetic of fouling. Molecular modelling with density functional theory is first carried out to determine the energy of CaCO3 deposition on anatase (1 0 1), (0 0 4), and (2 0 0) surfaces as well as on a rutile (1 0 1) one. TiO2 thin films (thickness fouling results allows to draw general trends on the potential anti-scaling properties of TiO2 crystallized under various forms. Until now, such a comparison combining a theoretical approach with experimental fouling tests has never been reported in the literature.

  18. Microstructure optimization and optical and interfacial properties modulation of sputtering-derived HfO2 thin films by TiO2 incorporation

    Highlights: • Sputtering-derived Hf1−xTixO2 gate dielectrics have been deposited on Si substrates. • Increase in crystallization temperature and reduction in Eg have been observed. • Formation of silicate layer for 9% TiO2-doped HfO2/Si sample has been detected. - Abstract: TiO2-doped HfO2 gate dielectric thin films have been deposited on Si(1 0 0) substrates by RF sputtering. The component, morphology, structure, optical and interfacial properties of Hf1−xTixO2 films related to TiO2 concentration are systematically investigated by atomic force microscope (AFM), X-ray diffraction (XRD), spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy (XPS), and Fourier transformation infrared (FTIR). By employing Cauchy–Urbach model, the optical constants, such as refractive index (n), extinction coefficient (k), absorption coefficient (α), and optical band gap (Eg) have been determined precisely. Measurements from XRD have confirmed that TiO2 incorporating into HfO2 films leads to the increase of the crystallization temperature of HfO2 films with increasing the TiO2 concentration. SE analyses have indicated that reduction in band gap and refractive index has been observed with increasing the TiO2 component in Hf1−xTixO2 films. The increase in Urbach parameter EU with the increase of TiO2 concentration also suggests the rise in disorder for Hf1−xTixO2 films. FTIR measurements for Hf1−xTixO2/Si gate stack indicate the existence of the interfacial layer regardless of the TiO2 concentration. For the 9% TiO2-doped HfO2 samples, the shift in FTIR characteristic peak suggests the formation of the silicate layer, which leads to the suppressed interfacial layer growth during deposition. As a result, it can be conclude that the TiO2 component in Hf1−xTixO2 films should be controlled precisely to guarantee interfacial properties of Hf1−xTixO2/Si gate stacks

  19. Substrate dependant capacitive performance of spray pyrolysed titanium oxide (TiO2) thin films

    Fugare, B. Y.; Ingole, R. S.; Ambare, R. C.; Lokhande, B. J.

    2016-04-01

    Using 60 ml, 0.06 M aqueous solution of potassium titanium oxalate (pto), thin films of titanium oxide were prepared by using well known spray pyrolysis technique. Depositions of the films carried out at 723° K by maintain the spray rate 12 Cc/min. prepared thin films were characterized structurally, morphologically and electrochemically. Sample shows tetragonal crystal structure with rutile as prominent phase at very low deposition temperature. SEM morphology shows porous, dense, nanorods and nanoplates like morphology. The electrochemical cyclic voltammetery shows mixed capacitive behavior. The specific capacitance values observed from cyclic voltammetery in 1 M NaOH are 2497.19, 29.60, 424.22 F/g. for the electrode deposited on copper, FTO and stainless steel (SS) respectively. Charge discharge behavior was observed for the samples deposited on stainless steel gives specific energy (SE), specific power (SP) and efficiency (η) are 43.25 Wh/kg, 35.25 kW/kg and 98.22 % respectively. Impedance study was carried out in the frequency range 1 mHz to 1 MHz exhibits very less internal resistance 1.066 Ohm for the deposited electrode.

  20. Control of the visible and UV light water splitting and photocatalysis of nitrogen doped TiO2 thin films deposited by reactive magnetron sputtering

    Fakhouri, Houssam; Pulpytel, Jerome; Smith, Wilson; Zolfaghari, Alireza; Mortaheb, Hamid Reza; Meshkini, Fateme; Reza JAFARI; Sutter, Eliane; Arefi-Khonsari, Farzaneh

    2014-01-01

    N-doped TiO2 thin films have been prepared by reactive RF magnetron sputtering at different pressures and with different compositions using a dual reactive gas mixture of nitrogen and oxygen. The morphological, optical, photo-electrochemical and photocatalytic properties have been studied in order to investigate the white light and visible light photoactivities of the films. Significant control over the band gap energy in the films was achieved by varying the deposition parameters. Photoelect...

  1. Investigation of TiO2 Thin Film Growth by Layer-by-Layer Self-Assembly for Application to Optical Devices

    Kyung, Kyu-Hong; Fujimoto, Kouji; Shiratori, Seimei; Kim, Jin-Ho; Kim, Sae-Hoon

    2010-04-01

    Recently, optical thin films fabricated using a water-based process have been strongly demanded. We fabricated TiO2 thin films consisting of poly(diallyl dimethyl ammonium chloride) (PDDA) and titanium(IV) bis(ammonium lactate) dihydroxide (TALH) for optical devices fabricated using layer-by-layer self-assembly. We report the effects of the pH and concentration of a solution, immersion time, and the amount of NaCl added to a solution on the thickness, morphology, surface roughness, and transmittance of fabricated thin films. The thickness, surface morphology, and transparency of (PDDA/TALH) thin films were determined by ellipsometry, field-emission scanning microscopy (FE-SEM), atomic force microscopy (AFM), and ultraviolet-visible (UV-vis) spectrometry. It was found that the thickness and surface morphology of (PDDA/TALH) multilayer films can be controlled by adjusting the TiO2 particle size of TALH solution. TiO2 particle size was controlled by adjusting the pH of TALH solution and the concentration of PDDA solution, and by adding NaCl to PDDA solution. It was found that we can increase deposition speed while maintaining optical quality by suppressing the surface roughness within 10 nm. These experimental results showed that the fabrication speed of thin films can be markedly increased, by approximately 6-fold.

  2. Effect of annealing temperature on structural, morphological and electrical properties of nanoparticles TiO2 thin films by sol-gel method

    Muaz, A. K. M.; Hashim, U.; Arshad, M. K. Md.; Ruslinda, A. R.; Ayub, R. M.; Gopinath, Subash C. B.; Voon, C. H.; Liu, Wei-Wen; Foo, K. L.

    2016-07-01

    In this paper, the sol-gel method is used to prepare nanoparticles titanium dioxide (TiO2) thin films at different annealing temperature. The prepared sol was deposited on the p-SiO2 substrates by spin coating technique under room temperature. The nanoparticles TiO2 solution was synthesized using Ti{OCH(CH3)2}4 as a precursor with an methanol solution at a molar ratio 1:10. The prepared TiO2 sols will further validate through structural, morphological and electrical properties. From the X-ray diffraction (XRD) analysis, as-deposited films was found to be amorphous in nature and tend to transform into tetragonal anatase and rutile phase as the films annealed at 573 and 773 K, respectively. The diversification of the surface roughness was characterized by atomic force microscopy (AFM) indicated the roughness and thickness very dependent on the annealing temperature. The two-point probe electrical resistance and conductance of nanoparticles TiO2 thin films were determined by the DC current-voltage (IV) analysis. From the I-V measurement, the electrical conductance increased as the films annealed at higher temperature.

  3. PVD-Grown photocatalytic TiO2 thin films on PVDF substrates for sensors and actuators applications

    Titanium dioxide's self-cleaning effect has been broadly used in textiles, paints, windows, residual water treatment, amongst various other photocatalytic applications. Polymer substrates have found their way in the semiconductor industry as a base layer for flexible electronics, as well as in sensor and actuator applications. The optimum performance of these systems may be affected by dirt adsorbed on its surface, which can also originate mechanisms for the degradation of the polymer. These thin films have been deposited on electroactive poly(vinilidene fluoride) - PVDF - polymer substrates by unbalanced reactive magnetron sputtering. Rutherford Backscattering experiments evidenced that these coatings have a TiO2 stoichiometry. Raman spectroscopy experiments revealed that the as-deposited coatings on polymer substrates are mostly amorphous, however evidence of anatase and rutile nano-crystalline phases can be found. The photocatalytic behavior of the titanium dioxide coatings was determined by combined ultra-violet irradiation and absorption measurements of a particular dye in the presence of the catalyst. In order to assess the mechanical behavior of the as-sputtered films, the film/substrate composite system was loaded unidirectionally using a tensile testing machine. The stress-strain curves were analyzed and correlated with photocatalytic efficiency along these curves, as well as with the structural data

  4. Effect of pulsed bias on TiO2 thin films prepared on silicon by arc ion plating and simulation of pulsed plasma sheath dynamics

    Dielectric TiO2 thin films were fabricated on p-(100) Si substrates by arc ion plating. A pulsed substrate bias ranging from 0 V to − 900 V was applied to investigate the effect of pulsed bias on phase structure and growth of the films. Phase, microstructure, and growth morphology of TiO2 films prepared at different bias voltages were evaluated with grazing incident x-ray diffraction and atomic force microscopy (AFM). The results show that pulsed bias exerts an evident influence on phase structure and growth morphology. High substrate bias facilitates the formation of rutile phase, a (220) preferred orientation is observed in TiO2 films obtained at − 900 V. AFM images show that pulsed substrate bias exerts a strong influence on the growth of TiO2 films. With increasing bias voltage, the film is initially composed of tiny surface islands separated by shallow boundaries, then of large and spiky surface islands isolated by deep boundaries. Correspondingly, surface roughness increases from 1.1 nm at 0 V to 3.8 nm at − 900 V. To explain the phenomena observed in this study, pulsed plasma sheath model was used to simulate the ion sheath dynamics. By analyzing experimental and simulated results, it can be concluded that film growth and property relate close to ion density and energy in the sheath, which is dominantly governed by negative substrate bias.

  5. Prediction of TiO2 thin film growth on the glass beads in a rotating plasma chemical vapor deposition reactor.

    Kim, Dong-Joo; Kim, Kyo-Seon

    2010-05-01

    We calculated the concentration profiles of important chemical species for TiO2 thin film growth on the glass beads in the TTIP + O2 plasmas and compared the predicted growth rates of thin films with the experimental measurements. The film thickness profile depends on the concentration profile of TiO(OC3H7)3 precursors in the gas phase because TiO(OC3H7)3 is the main precursor of the thin film. The TTIP concentration decreases with time, while the TiO(OC3H7)3 concentration increases, and they reach the steady state about 2 approximately 3 sec. The growth rate of TiO2 film predicted in this study was 9.2 nm/min and is in good agreements with the experimental result of 10.5 nm/min under the same process conditions. This study suggests that a uniform TiO2 thin film on particles can be obtained by using a rotating cylindrical PCVD reactor. PMID:20358924

  6. ESR study of Co-doped TiO2 thin films

    Co:TiO2 thin films prepared by reactive co-sputtering deposition were studied by electron spin resonance (ESR) technique. Magnetization measurements showed hysteretic behavior with the coercive field between 55 and 65 Oe and the saturation magnetization at room temperature ranging from 7 (2.2% Co) to 28 emu/cm3 (8.5% Co). ESR measurements at X-band (9.5 GHz) revealed an anomaly in the temperature behavior of the absorption intensity near the temperature at 60 K. This behavior is attributed to an unconventional spin-glass-like behavior, which results from competition of long-range dipole-dipole interaction and anisotropy fields in ferromagnetic Co nanoparticles

  7. Microstructure Characterization of Sol-gel Prepared MoO3-TiO2 Thin Films for Oxygen Gas Sensors

    Yongxiang Li

    2000-01-01

    Binary metal oxide MoO3-TiO2 films have been prepared using the sol-gel technique. The thin films were annealed at several temperatures including 400℃,450℃,500℃,550℃ and 600℃ for lhour. The morphology, crystalline structure and chemical composition of the films have been analysed using SEM,XRD,RBS and XPS techniques. The SEM analysis showed that the films annealed at 450℃ are mainly smooth and uniform with 20-100nm-sized grains and with few particles as large as a micrometre or more. The XRD analysis revealed that the films annealed at 400℃ were a mixture of orthorhombic and hexagonal MoO3phases. The films annealed at 450℃ increased in hexagonal phase. The preferential orientation growth along(100) plane of the hexagonal phase and (010) plane of the orthorhombic phase has been found in both samples. RBS and XPS analysis showed that the films were stoichiometric. When the annealing temperature is increased to more than 500℃, the concentration ratio of MoO3 to TiO2 decreased due to the evaporation of MoO3. For the study of the electrical and gas sensing properties, films were deposited on sapphire substrates with interdigital electrodes on the front-side and a Pt heater on the backside. The O2 gas sensing properties of MoO3-TiO2 thin films are discussed.

  8. Solar photocatalytic degradation of gaseous formaldehyde by sol-gel TiO2 thin film for enhancement of indoor air quality

    Solar photocatalytic degradation of formaldehyde in the gaseous phase has been investigated. The tested photoreactor is made of a borosilicate glass tube with the inner surface coated with a sol-gel TiO2 thin film. In a pseudo-first-order Langmuir-Hinshelwood (L-H) model, the maximum reaction rate constant obtained is 0.148 min-1 under an exposure to sunlight with solar UVA irradiance of 1.56 mW/cm2. The solar photolysis effect is found to be negligible. It is also found that the sol-gel TiO2 thin film has a lower apparent photonic efficiency of solar photocatalysis than a Degussa P25 TiO2 coating. However, for the photonic efficiency taking into account the absorbed and scattered photons only and, in other words, excluding the transmitted photons, the thin film has a higher value. Based on a total of 28 measured data, an empirical-correlation equation has been developed to express the reactant residue with respect to the solar UVA irradiance and exposure time. A reasonable agreement between the correlation and experimental data is obtained. The findings of this investigation can be applied to design optimization of a honeycomb photoreactor made up of TiO2-coated glass tubes or polygonal cells. (author)

  9. High-κ TiO2 thin film prepared by sol-gel spin-coating method

    High-k TiO2 thin film on p-type silicon substrate was fabricated by a combined sol-gel and spin coating method. Thus deposited titania film had anatase phase with a small grain size of 16 nm and surface roughness of ≅ 0.6 nm. The oxide capacitance (Cox), flat band capacitance (CFB), flat band voltage (VFB), oxide trapped charge (Qot), calculated from the high frequency (1 MHz) C-V curve were 0.47 nF, 0.16 nF, − 0.91 V, 4.7x10−12 C, respectively. As compared to the previous reports, a high dielectric constant of 94 at 1 MHz frequency was observed in the devices investigated here and an equivalent oxide thickness (EOT) was 4.1 nm. Dispersion in accumulation capacitance shows a linear relationship with AC frequencies. Leakage current density was found in acceptable limits (2.1e-5 A/cm2 for −1 V and 5.7e-7 A/cm2 for +1 V) for CMOS applications

  10. Effects Of Tin Doping On Ethanol And Isopropyl Alcohol Sensing Properties Of Sol-Gel Derived TiO2 Thin Films

    In this work, ethanol and isopropyl alcohol sensing properties of Sn-doped TiO2 thin films were investigated. Sn-doped titanium dioxide (TiO2) films were prepared by sol-gel dipping technique using titanium (IV) n-butoxide and tin (IV) chloride pentahydrate as starting materials. The starting materials were dissolved in ethanol separately. Mixture of the solutions was stirred for 1 h. Sn-doped and undoped TiO2 thin films were deposited onto glass substrate patterned with interdigitated electrodes (IDT) by a sol-gel dipping process. Final curing were performed at 820 K in air for 2 h. The structure of the films was studied by X-ray diffraction. Sn:Ti ratio (wt.) was kept between the values of 5% and 11%. Response characteristics of the films were determined in the gas concentrations range of 10%-30%. Gas concentrations were controlled by mass flow controller. Gas sensing characteristics were obtained by recording the current values of the films versus time as a function of gas concentration at the temperatures of 300 and 525 K. The results showed that sensitivity of the films increases with increasing tin doping. We can conclude that tin doping to SnO2 films improve the sensing parameters.

  11. 锌掺杂多孔SiO2/TiO2薄膜制备及光催化性能研究%Preparation of Zn-doped SiO2/TiO2 thin films by sol-gel processing and their photocatalytic properties

    胡张顺; 姚伯龙; 鲍雪钦

    2013-01-01

    锌掺杂多孔SiO2/TiO2(多孔 Zn-SiO2/TiO2)复合薄膜自清洁玻璃以含聚乙二醇的钛醇盐和硅醇盐的复合溶胶前驱体通过浸渍提拉法制备.结果表明,在TiO2薄膜中添加SiO2可抑制TiO2晶粒长大,并提高TiO2薄膜的亲水性;随着聚乙二醇添加量的增加,锌掺杂多孔SiO2/TiO2薄膜的孔隙增多,表面积增大;经500℃煅烧的多孔Zn-SiO2/TiO2复合薄膜中,TiO2主要为催化效率高的锐钛矿相;多孔Zn-SiO2/TiO2复合薄膜表观光催化降解速率明显高于未掺锌多孔SiO2/TiO2薄膜.%The porous Zn-doped SiO2/TiO2(porous Zn-SiO2/TiO2) composite thin films on the glass substrate were prepared from alkoxide solutions containing polyethylene glycol(PEG) by sol-gel method. The results showed that the addition of SiO2 to TiO2 thin films can suppress the grain growth of TiO2 crystal in the TiO2 thin films, low the contact angle for water of TiO2 films; the pore size is adjusted by adding different amount of PEG, the anatase TiO2 can grow on the porous Zn-SiO2/TiO2 composite thin films at 500 ℃; studies of photocatalytic degradation show that the degradation rate of porous Zn-SiO2/TiO2 composite thin films were higher than that of un-doped porous SiO2/TiO2 composite thin films.

  12. Interdigitated electrode (IDE) for porcine detection based on titanium dioxide (TiO2) thin films

    Nordin, N.; Hashim, U.; Azizah, N.

    2016-07-01

    Interdigited Electrode (IDE) porcine detection can be accomplished to authenticate the halal issue that has been a concern to Muslim not only in Malaysia but all around the world. The method used is photolithography that used the p-type photoresist on the spin coater with 2500 rpm. Bare IDEs device is deposited with Titanium Dioxide (TiO2) to improve the performance of the device. The result indicates that current-voltage (I-V) measurement of porcine probe line slightly above porcine target due to negative charges repelled each other. The IDE device can detect the porcine presence in food as lowest as 1.0 µM. Better performance of the device can be achieved with the replacement of gold deposited to trigger more sensitivity of the device.

  13. Photooxidation of dibenzothiophene on TiO(2)/hectorite thin films layered catalyst.

    Robertson, Jamie; Bandosz, Teresa J

    2006-07-01

    A new titanium(IV) oxide-hectorite nanofilm photocatalyst was prepared on quartz slides. It was evaluated in the photooxidation of dibenzothiophene (DBT) in nonpolar organic solution (tetradecane), as a model for diesel fuel. A removal regimen was developed consisting of catalytic photooxidation followed by adsorption of products on silica gel. Photooxidation of DBT was performed with and without catalyst, at 254 and 300 nm. Comparison was made with a commercially available TiO(2) catalyst, Degussa P25. The catalyst was analyzed by nitrogen adsorption, XRD, SEM, and TGA-DTA. DBT concentrations were measured by HPLC and UV spectrophotometry. Preliminary qualititative analysis of products was performed by UV and HPLC. Results indicated that the outlined process was effective in reducing sulfur levels to below 10 ppm sulfur. PMID:16600276

  14. Atomic layer deposition of TiO2 thin films on nanoporous alumina templates: Medical applications

    Narayan, Roger J.; Monteiro-Riviere, Nancy A.; Brigmon, Robin L.; Pellin, Michael J.; Elam, Jeffrey W.

    2009-06-01

    Nanostructured materials may play a significant role in controlled release of pharmacologic agents for treatment of cancer. Many nanoporous polymer materials are inadequate for use in drug delivery. Nanoporous alumina provides several advantages over other materials for use in controlled drug delivery and other medical applications. Atomic layer deposition was used to coat all the surfaces of a nanoporous alumina membrane in order to reduce the pore size in a controlled manner. Neither the 20 nm nor the 100 nm TiO2-coated nanoporous alumina membranes exhibited statistically lower viability compared to the uncoated nanoporous alumina membrane control materials. Nanostructured materials prepared using atomic layer deposition may be useful for delivering a pharmacologic agent at a precise rate to a specific location in the body. These materials may serve as the basis for “smart” drug delivery devices, orthopedic implants, or self-sterilizing medical devices.

  15. Fabrication of TiO2/EP super-hydrophobic thin film on filter paper surface.

    Gao, Zhengxin; Zhai, Xianglin; Liu, Feng; Zhang, Ming; Zang, Deli; Wang, Chengyu

    2015-09-01

    A composite filter paper with super-hydrophobicity was obtained by adhering micro/nano structure of amorphous titanium dioxide on the filter paper surface with modifying low surface energy material. By virtue of the coupling agent, which plays an important part in bonding amorphous titanium dioxide and epoxy resin, the structure of super-hydrophobic thin film on the filter paper surface is extremely stable. The microstructure of super-hydrophobic filter paper was characterized by scanning electron microscopy (SEM), the images showed that the as-prepared filter paper was covered with uniform amorphous titanium dioxide particles, generating a roughness structure on the filter paper surface. The super-hydrophobic performance of the filter paper was characterized by water contact angle measurements. The observations showed that the wettability of filter paper samples transformed from super-hydrophilicity to super-hydrophobicity with the water contact angle of 153 ± 1°. Some experiments were also designed to test the effect of water-oil separation and UV-resistant by the super-hydrophobic filter paper. The prepared super-hydrophobic filter paper worked efficiently and simply in water-oil separation as well as enduringly in anti-UV property after the experiments. This method offers an opportunity to the practical applications of the super-hydrophobic filter paper. PMID:26005136

  16. TiO2 thin films with rutile phase prepared by DC magnetron co-sputtering at room temperature: Effect of Cu incorporation

    Wang, Hui; Li, Yujie; Ba, Xin; Huang, Lin; Yu, Ying

    2015-08-01

    The thin films for pure TiO2 and that incorporated with Cu ion were deposited by DC magnetron co-sputtering with Ar gas. The crystal texture, surface morphology, energy gap and optical properties of the prepared films have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectrometer (XPS), UV-vis spectrophotometer, and Raman spectroscopy. The results show that as-deposited TiO2 film mainly possesses anatase structure at room temperature with pure Ar gas, but the introduction of Cu can alter the phase structure of crystallite TiO2. XRD patterns and Raman spectra indicate that the Cu incorporation with high concentration (ACu/ATi + ACu ≈ 20%) favors the formation of rutile phase. Moreover, the Cu incorporation into TiO2 lattice induces band gap narrowing. Band structures and density of states have been analyzed based on density functional theory (DFT) and periodic models in order to investigate the influence of the Cu incorporation on the electronic structure of TiO2. Both experimental data and electronic structure calculations evidence the fact that the change in film structure from the anatase to the rutile phase can be ascribed to the possible incorporation of Cu1+ in the sites previously occupied by Ti4+, and the presence of Cu results in important effect on the electronic states, which is mainly related to the 3d Cu orbitals in the gap and in the vicinity of the valence band edges for TiO2.

  17. KARAKTERISTIK FILM TIPIS TiO2 DOPING NIOBIUM

    Bilalodin

    2010-05-01

    Full Text Available Niobium (Nb doped Titanium dioxide (TiO2 thin films have been successfully grown using spin coating method. Characterizations of thin films was carried out using EDAX (Energy Dispersion Analysis for X-Ray, XRD (X-Ray Diffaction and SEM (Scanning Electron Microscope to determine the microstructure of thin films. Determination microstructure, particularly of crystal structure was examined using ICDD data, whereas porosity calculation was done using the toolbox application on Matlab 6.1 software. EDAX, XRD and SEM characterization show that the thin films grown well at the Si substrates with the (002 field orientation is dominant and the thin film has the rutile structure. The TiO2 : Nb thin films product have granules round, uniform grain size and porosity value of about 41%.

  18. Humidity sensing properties of La~(3+)/Ce~(3+)-doped TiO_2-20 wt.% SnO_2 thin films derived from sol-gel method

    李红霞; 史志铭; 刘红伟

    2010-01-01

    The humidity sensing properties of La3+/Ce3+-doped TiO2-20 wt.%SnO2 thin films were studied.Sol-gel method was employed to prepare the films on alumina substrates.By constructing a humidity-impedance measuring system,the sensing behaviors were inspected for the films sintered at different temperatures.Experimental results showed that,0.5 wt.% of La2O3 or Ce2O3 doped films sintered at 500 °C for 2 h had the best humidity sensing properties,the impedance decreasing from 109 ? to below 104 ? in the humidity ra...

  19. Effects of reductive annealing on insulating polycrystalline thin films of Nb-doped anatase TiO2: recovery of high conductivity

    Nakao, Shoichiro; Hirose, Yasushi; Hasegawa, Tetsuya

    2016-02-01

    We studied the effects of reductive annealing on insulating polycrystalline thin films of anatase Nb-doped TiO2 (TNO). The insulating TNO films were intentionally fabricated by annealing conductive TNO films in oxygen ambient at 400 °C. Reduced free carrier absorption in the insulating TNO films indicated carrier compensation due to excess oxygen. With H2-annealing, both carrier density and Hall mobility recovered to the level of conducting TNO, demonstrating that the excess oxygen can be efficiently removed by the annealing process without introducing additional scattering centers.

  20. Wet Etching of Amorphous TiO2 Thin Films Using H3PO4-H2O2 Aqueous Solution

    Okazaki, Sohei; Ohhashi, Takuya; Nakao, Shoichiro; Hirose, Yasushi; Hitosugi, Taro; Hasegawa, Tetsuya

    2013-09-01

    We report on the wet etching of amorphous undoped and Nb-doped TiO2 thin films using H3PO4-H2O2 etching solution. The etching rate (R) showed a maximum at a H3PO4 concentration of approximately 50 wt % at 80 °C, suggesting that H2PO4- and/or H3O+ is responsible for the etching reaction. The addition of H2O2 to H3PO4 solution significantly enhanced R, and an optimized solution exhibited an R of 13 nm/min at 80 °C, which is one order of magnitude higher than that using H2SO4. These results demonstrate that H3PO4-H2O2 aqueous solution is an effective etchant for TiO2-based amorphous thin films.

  1. Effects of the interfacial layer on electrical characteristics of Al 2O 3/TiO 2/Al 2O 3 thin films for gate dielectrics

    Kim, Chang Eun; Yun, Ilgu

    2012-01-01

    Effects of thermal annealing on the electrical properties of Al2O3/TiO2/Al2O3 (ATA) dielectric thin films prepared by atomic layer deposition are investigated. The structural properties and chemical states in the interfacial layer are analyzed with varying the annealing temperature. The dielectric constant and leakage current are affected by the formation of Al2O3-TiO2 composite and interfacial layer including SiOx in the interface by the annealing. The transformation of interfacial layer at the interface of the ATA/Si substrate due to the annealing is a critical point to apply ATA thin films as gate dielectric layers.

  2. Processing, characterization and photocatalytic properties of Cu doped TiO2 thin films on glass substrate by sol-gel technique

    The present paper describes processing, properties and photocatalytic application of Cu doped TiO2 thin films on glass substrate. Cu doped TiO2 coatings were successfully prepared on glass slide substrates using sol-gel method. The obtained solutions exhibit acidic characteristics. The phase structure, thermal, microstructure and surface properties of the coatings were characterized by using XRD, DTA/TG, SEM and AFM. Their adhesion properties and spectroscopic analysis were investigated by a scratch tester and UV-vis spectroscopy. Four different solutions were prepared by changing Cu/Ti ratios. Glass substrates were coated by solutions of Ti-alkoxide, Cu-chloride, glacial acetic acid and isopropanol. The obtained gel films were dried at 300 deg. C for 10 min and subsequently heat-treated at 500 deg. C for 5 min in air. The oxide thin films were annealed at 600 deg. C for 60 min in air. TiO2, CuO, Cu4Ti, Ti3O5 and Cu3TiO4 phases were found in the coating. The organic matters were burned at temperatures between 200 and 350 deg. C and TiO2 crystallization was formed at 450 deg. C. The weight loss of the powder during process up to 600 deg. C is approximately 70%. The microstructural observations demonstrated that CuO content was led an improved surface morphology while thickness of the film and surface defects were increased in accordance with number of dipping. According to AFM results, it was found that as the Cu/Ti content increases the surface roughness of the films increases. In addition structural, thermal and microstructural results, it was found that the films of 0.73 ratio have better adhesion strength to the glass substrate among other coatings. The oxide films were found to be active for photocatalytic decomposition of metylene blue

  3. Antifungal activity of Ag:hydroxyapatite thin films synthesized by pulsed laser deposition on Ti and Ti modified by TiO2 nanotubes substrates

    Eraković, S.; Janković, A.; Ristoscu, C.; Duta, L.; Serban, N.; Visan, A.; Mihailescu, I. N.; Stan, G. E.; Socol, M.; Iordache, O.; Dumitrescu, I.; Luculescu, C. R.; Janaćković, Dj.; Miškovic-Stanković, V.

    2014-02-01

    Hydroxyapatite (HA) is a widely used biomaterial for implant thin films, largely recognized for its excellent capability to chemically bond to hard tissue inducing the osteogenesis without immune response from human tissues. Nowadays, intense research efforts are focused on development of antimicrobial HA doped thin films. In particular, HA doped with Ag (Ag:HA) is expected to inhibit the attachment of microbes and contamination of metallic implant surface. We herewith report on nano-sized HA and Ag:HA thin films synthesized by pulsed laser deposition on pure Ti and Ti modified with 100 nm diameter TiO2 nanotubes (fabricated by anodization of Ti plates) substrates. The HA-based thin films were characterized by SEM, AFM, EDS, FTIR, and XRD. The cytotoxic activity was tested with HEp2 cells against controls. The antifungal efficiency of the deposited layers was tested against the Candida albicans and Aspergillus niger strains. The Ti substrates modified with TiO2 nanotubes covered with Ag:HA thin films showed the highest antifungal activity.

  4. Low temperature growth study of nano-crystalline TiO2 thin films deposited by RF sputtering

    Precise control of the various structural phases of TiO2 at a low temperature is particularly important for practical applications. In this work, the deposition conditions for the growth of anatase and rutile phase at a low temperature (⩽300 °C) were optimized. TiO2 films were deposited by radio frequency (RF) sputtering of a ceramic TiO2 target in argon and argon-oxygen plasma (10 and 20% O2) at room temperature. For the films deposited in pure Ar and 20% O2, the growth temperature was varied from 25 to 400 °C. The plasma properties were investigated using optical emission spectroscopy (OES) in a wide range of values of gas composition (0–50% O2 in Ar-O2 mixture). The structural and chemical properties were characterized by means of x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS). The results indicate that O2 addition to the Ar-O2 gas mixture significantly changed the density of the plasma species (Ar, Ar+, Ti, Ti+ and O), which in turn influence the crystal structure and surface chemistry of the prepared films. Anatase phase was obtained for the films grown in Ar-O2 plasma over the whole range of temperature. In contrast, the films deposited in argon discharge largely persist in amorphous phase at temperature ⩽200 °C and revealed the formation of single rutile phase at ⩾300 °C. The oxygen vacancies detected by XPS analysis for the films deposited in Ar plasma facilitate the growth of a rutile phase at low temperature (∼300 °C). Our results demonstrate that oxygen negative ions, oxygen vacancies and surface energy conditions at the substrate are the key parameters controlling the phase of the prepared films at low temperature. (paper)

  5. Low temperature growth study of nano-crystalline TiO2 thin films deposited by RF sputtering

    Safeen, K.; Micheli, V.; Bartali, R.; Gottardi, G.; Laidani, N.

    2015-07-01

    Precise control of the various structural phases of TiO2 at a low temperature is particularly important for practical applications. In this work, the deposition conditions for the growth of anatase and rutile phase at a low temperature (⩽300 °C) were optimized. TiO2 films were deposited by radio frequency (RF) sputtering of a ceramic TiO2 target in argon and argon-oxygen plasma (10 and 20% O2) at room temperature. For the films deposited in pure Ar and 20% O2, the growth temperature was varied from 25 to 400 °C. The plasma properties were investigated using optical emission spectroscopy (OES) in a wide range of values of gas composition (0-50% O2 in Ar-O2 mixture). The structural and chemical properties were characterized by means of x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS). The results indicate that O2 addition to the Ar-O2 gas mixture significantly changed the density of the plasma species (Ar, Ar+, Ti, Ti+ and O), which in turn influence the crystal structure and surface chemistry of the prepared films. Anatase phase was obtained for the films grown in Ar-O2 plasma over the whole range of temperature. In contrast, the films deposited in argon discharge largely persist in amorphous phase at temperature ⩽200 °C and revealed the formation of single rutile phase at ⩾300 °C. The oxygen vacancies detected by XPS analysis for the films deposited in Ar plasma facilitate the growth of a rutile phase at low temperature (˜300 °C). Our results demonstrate that oxygen negative ions, oxygen vacancies and surface energy conditions at the substrate are the key parameters controlling the phase of the prepared films at low temperature.

  6. Structural Modification of Sol-Gel Synthesized V2O5 and TiO2 Thin Films with/without Erbium Doping

    Fatma Pınar Gökdemir

    2014-01-01

    Full Text Available Comparative work of with/without erbium- (Er- doped vanadium pentoxide (V2O5 and titanium dioxide (TiO2 thin films were carried out via sol-gel technique by dissolving erbium (III nitrate pentahydrate (Er(NO33·5H2O in vanadium (V oxoisopropoxide (OV[OCH(CH32]3 and titanium (IV isopropoxide (Ti[OCH(CH32]4. Effect of Er doping was traced by Fourier transform IR (FTIR, thermogravimetric/differential thermal (TG/DTA, and photoluminescence measurements. UV-Vis transmission/absorption measurement indicated a blue shift upon Er doping in V2O5 film due to the softening of V=O bond while appearance of typical absorption peaks in Er-doped TiO2 film. Granule size of the films increased (reduced upon Er substitution on host material compared to undoped V2O5 and TiO2 films, respectively.

  7. Electrical investigation of TiO2 thin films coated on glass and silicon substrates—effect of UV and visible light illumination

    Amirtharajan, Saranya; Jeyaprakash, Pandiarajan; Natarajan, Jeyakumaran; Natarajan, Prithivikumaran

    2016-04-01

    The conducting nature of nanocrystalline TiO2 thin film coated on glass and silicon (Si) substrates was studied in detail. The films were prepared through sol-gel spin-coating method with variation in coating parameters viz, the thickness of the film and the post annealing temperature. The thickness of the films was measured using Stylus profilometer. The resistivity of the film, as a function of film thickness, under the illumination of UV, visible light, and dark conditions was found using the four-probe method. The results show that the resistivity of the film decreases with increase in thickness of the film. The decrease in resistivity of the film is attributed to increase in cross-sectional area and rearrangement and removal of defects. Illumination of the samples under visible and UV light further decreases the resistivity of the film. The electrical resistivity of TiO2 film coated on Si substrate was observed to be lesser than that of the glass substrate.

  8. Optimization and comparative evaluation of optical and photocatalytic properties of TiO2 thin films prepared via sol–gel method

    Mohd. Danish

    2015-09-01

    Full Text Available TiO2 thin films were fabricated with optimization of the synthesis parameters for efficient photocatalysis. The films were sculptured from gels obtained from Ti(OiPr4 and Ti(OBus4 via spin coating at different rotation speed ranging from 1000 rpm to 3000 rpm. Thicknesses of the films were in the range of ≈112–160 nm. The X-ray diffractograms showed a phase transformation from anatase to rutile along with an increase in average crystallite size from 11 nm to 18 nm with a decrease in thickness of the films. Refractive index (n values of the films were in the range of 2.50–3.45 while extinction coefficient (k values ranged from 0.090 to 0.860. These films were transparent with high transmittance (T ⩽ 95% in the visible region. The optical band gaps for films were calculated to be in the range of 3.00–3.95 eV. Photocatalytic degradations of methylene blue by the fabricated TiO2 thin films have also been investigated.

  9. STS study of TiO2 film and Pt-deposited TiO2 film in air

    Zhang Min; Jin Zhensheng

    2004-01-01

    Direct investigation of the electronic structure of catalyst surfaces on the near-atomic scale in general has not been impossible in the past. However, with the advent of the scanning tunneling microscope (STM), the opportunity arises for incorporating the scanning tunneling spectroscopy (STS) for correlation in-situ surface electronic structure with topography on a sub-nanometer scale. In this paper, we report the STS results of thin film TiO2 and Pt-deposited TiO2 annealed at 450℃. It was found that the TiO2 semiconductor changes from n-type to p-type after Pt deposition.Fig. 1 shows the surface electronic property (Ⅰ-Ⅴ curve) of thin TiO2 film measured in air by STS. A steep descent of the anodic tunneling current at ca.- 1.0 Ⅴ and a rapid ascent of cathodic tunneling current at ca. +2.0V. The zero bias represents the Fermi level (Ef). Ef is situated at the Ecb side indicating that the thin TiO2 film possesses the same band gap as that of bulk TiO2 phase ( Egs =3.0 to 3.2 eV). For the sample of Pt-deposited TiO2 film, Pt/(Pt+Ti+O) atomic ratio≈0.2, which indicates that the surface of TiO2 film is partly covered by Pt particles, and there are two types of Ⅰ-Ⅴ curves to be detected. One of them (Fig.2a)is attributed to the electronic property of TiO2, which has same Egs as that shown in Fig. 1. However, the Ef is transferred to valence side (△≈1eV). This phenomenon hints that TiO2 is doped by an impurity which can introduce h+ into TiO2 lattice.Such a type of defects may be described by Ti1-xPtxO2(h )2x, here Pt+2 as a substitutional site of Ti+4. Fig.2b is the Ⅰ-Ⅴ curve of a Pt particle situated on a TiO2 particle contained Ti1-xPtxO2(h )2x.

  10. Photocatalytic performance of Sn-doped and undoped TiO2 nanostructured thin films under UV and vis-lights

    Sn-doped and undoped nano-TiO2 particles have been synthesized by hydrotermal process without solvent at 200 deg. C in 1 h. Nanostructure-TiO2 based thin films have been prepared on glass substrate by spin-coating technique. The structure, surface morphology and optical properties of the thin films and the particles have been investigated by element analysis and XRD, SEM, BET and UV-vis-NIR techniques. The photocatalytic performance of the films were tested for degradation of Malachite Green dye in solution under UV and vis-lights. The results showed that (a) hydrothermally synthesized nano-TiO2 particles are fully anatase crystalline form and are easily dispersed in water, (b) the coated surfaces have nearly super-hydrophilic properties and (c) the doping of transition metal ion efficiently improved the photocatalytic performance of the TiO2 thin film

  11. Photocatalytic performance of Sn-doped TiO2 nanostructured thin films for photocatalytic degradation of malachite green dye under UV and VIS-lights

    Sn-doped and undoped nano-TiO2 particles have been synthesized by hydrotermal process without acid catalyst at 225 deg. C in 1 h. Nanostructure-TiO2 based thin films, contain at different solid ratio of TiO2 in coating, have been prepared on glass surfaces by spin-coating technique. The structure, surface morphology and optical properties of the thin films and the particles have been investigated by element analysis and XRD, BET and UV/VIS/NIR techniques. The photocatalytic performance of the films was tested for degradation of malachite green dye in solution under UV and VIS-lights. The results showed that the hydrothermally synthesized nano-TiO2 particles are fully anatase crystalline form and are easily dispersed in water, the coated surfaces have nearly super-hydrophilic properties and, the doping of transition metal ion efficiently improved the photocatalytic performance of the TiO2 thin film. The results also proved that malachite green is decomposed catalytically due to the pseudo first-order reaction kinetics

  12. Effect of crystal structure on photoinduced superhydrophilicity of copper grafted TiO2 nanostructure thin film

    Akbar Eshaghi; Ameneh Eshaghi

    2013-02-01

    In this work, copper grafted titanium dioxide (rutile and brookite) thin films were deposited on glass substrates using the dip-coatingmethod. Field emission scanning electron microscopy and X-ray photoelectron spectroscopy were used to evaluate the surface morphology and properties of the film surfaces. The water contact angle on the film surfaces during irradiation and storage in a dark place was measured by a contact angle analyser. The results indicate that copper grafted titanium dioxide brookite thin film showed higher hydrophilicity than copper grafted titania rutile thin film.

  13. Dye sensitized solar cell applications of CdTiO3-TiO2 composite thin films deposited from single molecular complex

    Ehsan, Muhammad Ali; Khaledi, Hamid; Pandikumar, Alagarsamy; Huang, Nay Ming; Arifin, Zainudin; Mazhar, Muhammad

    2015-10-01

    A heterobimetallic complex [Cd2Ti4(μ-O)6(TFA)8(THF)6]·1.5THF (1) (TFA=trifluoroacetato, THF=tetrahydrofuran) comprising of Cd:Ti (1:2) ratio was synthesized by a chemical reaction of cadmium (II) acetate with titanium (IV) isopropoxide and triflouroacetic acid in THF. The stoichiometry of (1) was recognized by single crystal X-ray diffraction, spectroscopic and elemental analyses. Thermal studies revealed that (1) neatly decomposes at 450 °C to furnish 1:1 ratio of cadmium titanate:titania composite oxides material. The thin films of CdTiO3-TiO2 composite oxides were deposited at 550 °C on fluorine doped tin oxide coated conducting glass substrate in air ambient. The micro-structure, crystallinity, phase identification and chemical composition of microspherical architectured CdTiO3-TiO2 composite thin film have been determined by scanning electron microscopy, X-ray diffraction, Raman spectroscopy and energy dispersive X-ray analysis. The scope of composite thin film having band gap of 3.1 eV was explored as photoanode for dye-sensitized solar cell application.

  14. Semi-transparent ordered TiO2 nanostructures prepared by anodization of titanium thin films deposited onto the FTO substrate

    Szkoda, Mariusz; Lisowska-Oleksiak, Anna; Grochowska, Katarzyna; Skowroński, Łukasz; Karczewski, Jakub; Siuzdak, Katarzyna

    2016-09-01

    In a significant amount of cases, the highly ordered TiO2 nanotube arrays grow through anodic oxidation of a titanium metal plate immersed in electrolyte containing fluoride ions. However, for some practical applications, e.g. solar cells or electrochromic windows, the semi-transparent TiO2 formed directly on the transparent, conductive substrate is very much desired. This work shows that high-quality Ti coating could be formed at room temperature using an industrial magnetron sputtering system within 50 min. Under optimized conditions, the anodization process was performed on 2 μm titanium films deposited onto the FTO (fluorine-tin-oxide) support. Depending on the electrolyte type, highly ordered tubular or porous titania layers were obtained. The fabricated samples, after their thermal annealing, were investigated using scanning electron microscopy, Raman spectroscopy and UV-vis spectroscopy in order to investigate their morphology, crystallinity and absorbance ability. The photocurrent response curves indicate that materials are resistant to the photocorrosion process and their activity is strongly connected to optical properties. The most transparent TiO2 films were fabricated when Ti was anodized in water electrolyte, whereas the highest photocurrent densities (12 μA cm-2) were registered for titania received after Ti anodization in ethylene glycol solution. The obtained results are of significant importance in the production of thin, semi-transparent titania nanostructures on a commercial scale.

  15. Photocatalytic activity of bipolar pulsed magnetron sputter deposited TiO2/TiWOx thin films

    Weng, Ko-Wei; Hu, Chung-Hsuan; Hua, Li-Yu; Lee, Chin-Tan; Zhao, Yu-Xiang; Chang, Julian; Yang, Shu-Yi; Han, Sheng

    2016-08-01

    Titanium oxide films were formed by sputtering and then TiWOx films were deposited by bipolar pulsed magnetron sputtering with pure titanium and tungsten metal targets. The sputtering of titanium oxide with tungsten enhanced the orientation of the TiO2 (1 0 1) plane of the specimen assemblies. The main varying parameter was the tungsten pulse power. Titanium oxide sputtered with tungsten using a pulsing power of 50 W exhibited a superior hydrophilic property, and a contact angle of 13.1°. This fabrication conditions maximized the photocatalytic decomposition of methylene blue solution. The mechanism by which the titanium oxide was sputtered with tungsten involves the photogeneration of holes and electron traps, inhibiting the hole-electron recombination, enhancing hydrophilicity and reducing the contact angle.

  16. The structural studies of Ag containing TiO2-SiO2 gels and thin films deposited on steel

    Adamczyk, Anna; Rokita, Magdalena

    2016-06-01

    FTIR spectroscopic structural studies of titania-silica monolith samples as well as thin films deposited on steel were described in this work. Thin films were synthesized by the sol-gel method applying the dip coating as separate one-component TiO2 and/or SiO2 layers or as two-component TiO2-SiO2 thin films. Silver nanoparticles were incorporated into the structure from pure SiO2 sol, deposited then as an additional layer in those hybrid multilayers systems. Except the spectroscopic studies, XRD diffraction, SEM microscopy with EDX analysis and AFM microscopy were applied. The structural studies allow to describe and compare the structure and the morphology of thin films, as well those Ag free as Ag containing ones, also by the comparison with the structure of bulk samples. In FTIR spectra, the band observed at about 613 cm-1 can be connected with the presence of the non-tetrahedral cation in the structure and is observed only in the spectra of Ag containing bulk samples and thin films. The bands at 435-467 cm-1 are due to the stretching vibrations of Ti-O bonds or as well to the bending vibrations of O-Si-O one. In the ranges of 779-799 cm-1 and 1027-1098 cm-1, the bands ascribed to the symmetric stretching vibrations and asymmetric vibrations of Si-O-Si connections, respectively, are observed. SEM and AFM images gave the information on the microstructure and the topography of samples surface. XRD measurements confirmed the presence of only amorphous phase in samples up to 500 °C and allowed to observe the tendency of their crystallization.

  17. Real-time identification of the evolution of conducting nano-filaments in TiO2 thin film ReRAM.

    Song, Seul Ji; Seok, Jun Yeong; Yoon, Jung Ho; Kim, Kyung Min; Kim, Gun Hwan; Lee, Min Hwan; Hwang, Cheol Seong

    2013-01-01

    Unipolar resistance switching (RS) in TiO2 thin films originates from the repeated formation and rupture of the Magnéli phase conducting filaments through repeated nano-scale phase transitions. By applying the Johnson-Mehl-Avrami (JMA) type kinetic model to the careful analysis on the evolution of transient current in a pulse-switching, it was possible to elucidate the material specific evolution of the Magnéli phase filament. This methodology was applied to the two types of TiO2 films grown by plasma-enhanced atomic layer deposition (PEALD) and sputtering. These two samples have structurally and electrically distinctive properties: PEALD film exhibited high variability in switching parameters and required an electroforming while sputtered film showed higher uniformity without distinct electroforming process. The JMA-type kinetic analysis of the RS behaviors revealed that the rejuvenation of the filament is accomplished by repeated one-dimensional nucleation followed by a two-dimensional growth in PEALD samples, whereas one-dimensional nucleation-free mechanism dominates in sputtered films. PMID:24309421

  18. Effect of variation of precursor concentration on structural, microstructural, optical and gas sensing properties of nanocrystalline TiO2 thin films prepared by spray pyrolysis techniques

    Lalchand A Patil; Dinesh N Suryawanshi; Idris G Pathan; Dhanashri G Patil

    2013-12-01

    The objective of the present paper is to investigate the effect of variation of precursor concentration (0.01, 0.02 and 0.03 M) on the structural, microstructural, optical and gas sensing properties of TiO2 thin films. Titanium dioxide (TiO2) films were prepared from aqueous solution of titanium chloride (TiCl3.6H2O, 99.9%pure, Merckmade, Germany) onto the glass substrates heated at a temperature of 350 °C by the spray pyrolysis technique. Bandgap energy of the films vary from 3.28 to 3.29 eV. X-ray diffraction shows that films to be nanocrystalline with anatase phase having tetragonal crystal structure. The values calculated from electron diffraction patterns (TEM) were observed to be matching with values calculated from XRD. Transmission electron microscopy (TEM) reveled that grain sizes were observed to increase (10–29 nm) with an increase in the concentration of precursor solution. The gas sensing performance of the films was tested.

  19. Interposition fixing structure of TiO2 film deposited on activated carbon fibers

    FU Ping-feng; LUAN Yong; DAI Xue-gang

    2006-01-01

    The immobilized photocatalyst, TiO2 film supported on activated carbon fibers (TiO2/ACFs) prepared with molecular adsorption-deposition (MAD), exhibits high stability in cyclic photodegradation runs. The interposition fixing structure between TiO2 film and carbon fiber was investigated by means of SEM-EDX, XRD, XPS and FTIR, and a model was proposed to explain this structure. With SEM examination of carbon fiber surface after removing the deposited TiO2 film, a residual TiO2 super-thin film was found to exist still. By determining surface groups on ACFs, titanium sulfate (Ti2(SO4)3) in burnt remainders of the TiO2/ACFs was thought to be formed with an interfacial reaction between TiO2 film and carbon fibers. These provide some evidence of firm attachment of TiO2 film to carbon fiber surface. In the consideration of characteristics of the MAD, the deposition mechanism of TiO2 film on ACFs was proposed, and the interposition fixing structure was inferred to intercrossedly form between TiO2 film and ACFs' surface. This structure leaded to firm attachment and high stability of the TiO2 film.

  20. Photocatalytic Antibacterial Performance of Glass Fibers Thin Film Coated with N-Doped SnO2/TiO2

    Peerawas Kongsong

    2014-01-01

    Full Text Available Both N-doped and undoped thin films of 3SnO2/TiO2 composite were prepared, by sol-gel and dip-coating methods, and then calcined at 600°C for 2 hours. The films were characterized by FTIR, XRD, UV-Vis, SEM, and XPS, and their photocatalytic activities to degrade methylene blue in solution were determined, expecting these activities to correlate with the inactivation of bacteria, which was confirmed. The doped and undoped films were tested for activities against Gram-negative Escherichia coli (E. coli and Salmonella typhi (S. typhi, and Gram-positive Staphylococcus aureus (S. aureus. The effects of doping on these composite films included reduced energy band gap, high crystallinity of anatase phase, and small crystallite size as well as increased photocatalytic activity and water disinfection efficiency.

  1. SiO2/TiO2/n-Si/Ag(Cr)/TiO2 thin films with superhydrophilicity and low-emissivity

    Loka, Chadrasekhar; Ryeol Park, Kyoung; Lee, Kee-Sun

    2016-01-01

    In this study, SiO2/TiO2/n-Si/Ag(Cr)/TiO2 multilayer structures have been designed and deposited by the RF and DC magnetron sputtering at room temperature. The as-deposited TiO2/glass films which are initially amorphous in nature were subjected to post annealing at 673 K for anatase phase TiO2. The anatase TiO2 films showed an optical bandgap ˜3.32 eV. The Ag(Cr)/TiO2 showed very low-emissivity (low-e) value ˜0.081 which is evaluated by using the sheet resistance (6.51 Ω/□) of the films. All the deposited films showed high visible transmittance (˜81%) and high infrared reflectance (72%) which are recorded by using the UV-vis-NIR spectrophotometer. In addition, experimentally obtained optical properties were in good agreement with the simulation data. The TiO2/n-Si heterojunction concept has been employed to enhance the superhydrophilicity of the deposited multilayer stack, TiO2/n-Si/Ag(Cr)/TiO2 films exhibited best superhydrophilicity with water contact angle ˜2°. The deposited multilayer structures SiO2/TiO2/n-Si/Ag(Cr)/TiO2 and TiO2/n-Si/Ag(Cr)/TiO2 achieved significant low-e and superhydrophilicity.

  2. TiO2/SiO2纳米薄膜的光催化活性和亲水性%Photocatalytic Activity and Hydrophilic Property of TiO2/SiO2 Composite Nanometer Thin Films

    余家国; 赵修建; 陈文梅; 林立; 张艾丽

    2001-01-01

    通过 sol-gel工艺在钠钙玻璃表面制备了均匀透明的 TiO2/SiO2复合纳米薄膜 .实验结果表明 : 当 SiO2添加量较高时 , TiO2/SiO2复合纳米薄膜的光催化活性明显降低 ;当 SiO2添加量较低时 ,TiO2/SiO2复合薄膜的光催化活性无明显变化 .在 TiO2薄膜中添加 SiO2,可以抑制薄膜中 TiO2晶粒的长大 ,同时薄膜表面的羟基含量增加 , 水在复合薄膜表面的润湿角下降 , 亲水能力增强 .当 SiO2含量为 10%- 20%(摩尔分数)时获得了润湿角为 0°的超亲水性薄膜 .%The uniform transparent TiO2/SiO2 composite nanometer thin films were prepared via sol-gel processing on the soda lime glass substrates.The photocatalytic activity of the as prepared TiO2/SiO2 composite nanometer thin films obviously decreases when the amount of SiO2 addition is large.However,the photocatalytic activity has no obvious change when the amount of SiO2 addition is small (Table 2).The addition of SiO2 can suppress the grain growth of TiO2 crystal,increase the hydroxyl content of TiO2 film,decrease the contact angle for water of TiO2 films and enhance the hydrophilic property of TiO2 films.The super-hydrophilic TiO2/SiO2 composite nanometer films with the contact angle of 0o were obtained by the addition of 10%- 20% (mole fraction) SiO2.

  3. Effect of defects in TiO2 nanotube thin film on the photovoltaic properties of quantum dot-sensitized solar cells

    In the liquid-phase-deposition (LPD) method, the deposition temperature is considered to be one of the most important factors in TiO2 nanotube crystal growth. We investigated the effects of the deposition temperature on the surface morphology and defects in TiO2 nanotube (NT–TiO2) thin film electrodes utilizing scanning-electron-microscopy (SEM), X-ray diffraction (XRD), and photoluminescence (PL), together with the effects of these on the photovoltaic characteristics of CdSe quantum dot (QD)-sensitized NT–TiO2 solar cells. In addition, we studied the effect of these defects on the physical properties, such as the carrier recombination and electron transport at the TiO2 and TiO2/QD interface. NT–TiO2 electrodes prepared at low temperatures have a more uniform surface and lower defects than those prepared at high temperatures. From the PL measurements and the photovoltaic characterization such as shunt resistance (Rsh) and open circuit voltage decay (OCVD), these defects can act as carrier recombination centers. The defect density increases with increasing deposition temperature, leading to an increase in carrier recombination. Series resistances (Rs) of the solar cells with NT–TiO2 electrodes prepared at high temperatures were larger than those of the solar cells with NT–TiO2 electrodes prepared at low temperatures, suggesting that the defects can also affect the carrier transport characteristics. Eventually, CdSe QD-sensitized NT–TiO2 solar cells employing NT–TiO2 prepared at low temperatures showed higher conversion efficiencies than those prepared at high temperatures

  4. Transport properties of ultra-thin VO2 films on (001) TiO2 grown by reactive molecular-beam epitaxy

    We report the growth of (001)-oriented VO2 films as thin as 1.5 nm with abrupt and reproducible metal-insulator transitions (MIT) without a capping layer. Limitations to the growth of thinner films with sharp MITs are discussed, including the Volmer-Weber type growth mode due to the high energy of the (001) VO2 surface. Another key limitation is interdiffusion with the (001) TiO2 substrate, which we quantify using low angle annular dark field scanning transmission electron microscopy in conjunction with electron energy loss spectroscopy. We find that controlling island coalescence on the (001) surface and minimization of cation interdiffusion by using a low growth temperature followed by a brief anneal at higher temperature are crucial for realizing ultrathin VO2 films with abrupt MIT behavior

  5. Transport properties of ultra-thin VO2 films on (001) TiO2 grown by reactive molecular-beam epitaxy

    Paik, Hanjong; Moyer, Jarrett A.; Spila, Timothy; Tashman, Joshua W.; Mundy, Julia A.; Freeman, Eugene; Shukla, Nikhil; Lapano, Jason M.; Engel-Herbert, Roman; Zander, Willi; Schubert, Jürgen; Muller, David A.; Datta, Suman; Schiffer, Peter; Schlom, Darrell G.

    2015-10-01

    We report the growth of (001)-oriented VO2 films as thin as 1.5 nm with abrupt and reproducible metal-insulator transitions (MIT) without a capping layer. Limitations to the growth of thinner films with sharp MITs are discussed, including the Volmer-Weber type growth mode due to the high energy of the (001) VO2 surface. Another key limitation is interdiffusion with the (001) TiO2 substrate, which we quantify using low angle annular dark field scanning transmission electron microscopy in conjunction with electron energy loss spectroscopy. We find that controlling island coalescence on the (001) surface and minimization of cation interdiffusion by using a low growth temperature followed by a brief anneal at higher temperature are crucial for realizing ultrathin VO2 films with abrupt MIT behavior.

  6. Photocatalytic performance of Sn-doped TiO2 nanostructured mono and double layer thin films for Malachite Green dye degradation under UV and vis-lights

    Nanostructure Sn4+-doped TiO2 based mono and double layer thin films, contain 50% solid ratio of TiO2 in coating have been prepared on glass surfaces by spin-coating technique. Their photocatalytic performances were tested for degradation of Malachite Green dye in solution under UV and vis irradiation. Sn4+-doped nano-TiO2 particle a doping ratio of about 5[Sn4+/Ti(OBu n)4; mol/mol%] has been synthesized by hydrotermal process at 225 deg. C. The structure, surface and optical properties of the thin films and/or the particles have been investigated by XRD, BET and UV/vis/NIR techniques. The results showed that the double layer coated glass surfaces have a very high photocatalytic performance than the other one under UV and vis lights. The results also proved that the hydrothermally synthesized nano-TiO2 particles are fully anatase crystalline form and are easily dispersed in water. The results also reveal that the coated surfaces have hydrophilic property

  7. Superhydrophobic ceramic coatings enabled by phase-separated nanostructured composite TiO2–Cu2O thin films

    By exploiting phase-separation in oxide materials, we present a simple and potentially low-cost approach to create exceptional superhydrophobicity in thin-film based coatings. By selecting the TiO2–Cu2O system and depositing through magnetron sputtering onto single crystal and metal templates, we demonstrate growth of nanostructured, chemically phase-segregated composite films. These coatings, after appropriate chemical surface modification, demonstrate a robust, non-wetting Cassie–Baxter state and yield an exceptional superhydrophobic performance, with water droplet contact angles reaching to ∼172° and sliding angles <1°. As an added benefit, despite the photo-active nature of TiO2, the chemically coated composite film surfaces display UV stability and retain superhydrophobic attributes even after exposure to UV (275 nm) radiation for an extended period of time. The present approach could benefit a variety of outdoor applications of superhydrophobic coatings, especially for those where exposure to extreme atmospheric conditions is required. (papers)

  8. Nanostructured Er3+-doped SiO2-TiO2 and SiO2-TiO2-Al2O3 sol-gel thin films for integrated optics

    Predoana, Luminita; Preda, Silviu; Anastasescu, Mihai; Stoica, Mihai; Voicescu, Mariana; Munteanu, Cornel; Tomescu, Roxana; Cristea, Dana

    2015-08-01

    The nanostructured multilayer silica-titania or silica-titania-alumina films doped with Er3+ were prepared by sol-gel method. The sol-gel method is a flexible and convenient way to prepare oxide films on several types of substrates, and for this reason it was extensively investigated for optical waveguides fabrication. The selected molar composition was 90%SiO2-10%TiO2 or 85%SiO2-10%TiO2-5% Al2O3 and 0.5% Er2O3. The films were characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Spectroellipsometry (SE), as well as by Atomic Force Microscopy (AFM) and photoluminescence (PL). The films deposited on Si/SiO2 substrate by dip-coating or spin-coating, followed by annealing at 900 °C, presented homogenous and continuous surface and good adherence to the substrate. Differences were noticed in the structure and properties of the prepared films, depending on the composition and the number of deposited layers. Channel optical waveguides were obtained by patterning Er3+-doped SiO2-TiO2 and SiO2-TiO2-Al2O3 sol-gel layers deposited on oxidized silicon wafers.

  9. Highly antibacterial activity of N-doped TiO2 thin films coated on stainless steel brackets under visible light irradiation

    Cao, Shuai; Liu, Bo; Fan, Lingying; Yue, Ziqi; Liu, Bin; Cao, Baocheng

    2014-08-01

    In this study, the radio frequency (RF) magnetron sputtering method was used to prepare a TiO2 thin film on the surface of stainless steel brackets. Eighteen groups of samples were made according to the experimental parameters. The crystal structure and surface morphology were characterized by X-ray diffraction, and scanning electron microscopy, respectively. The photocatalytic properties under visible light irradiation were evaluated by measuring the degradation ratio of methylene blue. The sputtering temperature was set at 300 °C, and the time was set as 180 min, the ratio of Ar to N was 30:1, and annealing temperature was set at 450 °C. The thin films made under these parameters had the highest visible light photocatalytic activity of all the combinations of parameters tested. Antibacterial activities of the selected thin films were also tested against Lactobacillus acidophilus and Candida albicans. The results demonstrated the thin film prepared under the parameters above showed the highest antibacterial activity.

  10. Highly antibacterial activity of N-doped TiO2 thin films coated on stainless steel brackets under visible light irradiation

    In this study, the radio frequency (RF) magnetron sputtering method was used to prepare a TiO2 thin film on the surface of stainless steel brackets. Eighteen groups of samples were made according to the experimental parameters. The crystal structure and surface morphology were characterized by X-ray diffraction, and scanning electron microscopy, respectively. The photocatalytic properties under visible light irradiation were evaluated by measuring the degradation ratio of methylene blue. The sputtering temperature was set at 300 °C, and the time was set as 180 min, the ratio of Ar to N was 30:1, and annealing temperature was set at 450 °C. The thin films made under these parameters had the highest visible light photocatalytic activity of all the combinations of parameters tested. Antibacterial activities of the selected thin films were also tested against Lactobacillus acidophilus and Candida albicans. The results demonstrated the thin film prepared under the parameters above showed the highest antibacterial activity.

  11. Anomalous C-V response correlated to relaxation processes in TiO2 thin film based-metal-insulator-metal capacitor: Effect of titanium and oxygen defects

    Kahouli, A.; Marichy, C.; Sylvestre, A.; Pinna, N.

    2015-04-01

    Capacitance-voltage (C-V) and capacitance-frequency (C-f) measurements are performed on atomic layer deposited TiO2 thin films with top and bottom Au and Pt electrodes, respectively, over a large temperature and frequency range. A sharp capacitance peak/discontinuity (C-V anomalous) is observed in the C-V characteristics at various temperatures and voltages. It is demonstrated that this phenomenon is directly associated with oxygen vacancies. The C-V peak irreversibility and dissymmetry at the reversal dc voltage are attributed to difference between the Schottky contacts at the metal/TiO2 interfaces. Dielectric analyses reveal two relaxation processes with degeneration of the activation energy. The low trap level of 0.60-0.65 eV is associated with the first ionized oxygen vacancy at low temperature, while the deep trap level of 1.05 eV is associated to the second ionized oxygen vacancy at high temperature. The DC conductivity of the films exhibits a transition temperature at 200 °C, suggesting a transition from a conduction regime governed by ionized oxygen vacancies to one governed by interstitial Ti3+ ions. Both the C-V anomalous and relaxation processes in TiO2 arise from oxygen vacancies, while the conduction mechanism at high temperature is governed by interstitial titanium ions.

  12. Photo-induced properties of thin TiO2 films deposited using the radio frequency plasma enhanced chemical vapor deposition method

    Thin titanium oxide films were deposited with the help of radio frequency plasma enhanced chemical vapor deposition technique. The RF power of deposition was applied as the operational parameter of the process, and optical properties, transmittance in particular, of the films were utilized as criterion for their selection. Photo-induced properties of the films, including a change of water wettability under the effect of illumination and photocatalytic activity, were studied. A substantial decrease of water contact angle was observed upon the irradiation of the films with ultraviolet (UV) light. The largest increase of water wettability was obtained for the surfaces of the films exhibiting the highest value of index of refraction. Testing of the photo-catalytic activity of the titanium oxide films comprised UV light-induced decomposition of benzene and aniline dissolved in water and bactericidal action against the Escherichia coli strain DH5α. The largest bactericidal efficiency was observed in the case of the film characterized by the highest index of refraction. Auger Electron Spectroscopy measurements have shown that the film composition is that of a nearly stoichiometric TiO2, with a small chlorine contamination

  13. Photocatalytic degradation of methylorange Using TiO2, WO3 and mixed thin films under controlled pH and H2O2.

    Carcel, Radu Adrian; Andronic, Luminita; Duta, Anca

    2011-10-01

    Wastewaters resulting from textile industry sector have a different chemistry compared with most of the other wastewaters. The different dyes in excess are usually very stable and even small quantities can have a major impact to the effluent. In order to treat these wastewaters, photodegradation is a largely investigated process that can be up-scaled. Photocatalysts based on wide band gap semiconductors can be used in heterogeneous photocatalysis and mostly reported are TiO2 and WO3. Under UV irradiation they form electron-hole pairs that produce active species that can oxidize the dye molecules. The electron-hole recombination represents the main cause for low efficiencies and is limited by the use of oxidant systems like H2O2. Doctor blade technique, a reproducible, up-scalable and low cost technique was used to obtain thin films. The reference dye, used in this experiment is methylorange in solution of 0.0125 mM, corresponding to average polluted water. In order to reduce the recombination in the catalysts, H2O2 is used. Another important aspect of the dye photocatalysis process, investigated in the paper is the adsorption of the dye molecule on the photocatalyst surface, strongly depending on pH which affects the dye's structure and the surface charge. Experiments are conducted at fixed pH values: 3, and respectively 7 covering values below and over the ZPC of the photocatalysts. The results show that TiO2/WO3 films have higher efficiency then the TiO2 and WO3 films, mainly due to the surface morphology of the films. By adding H2O2, higher efficiencies are obtained, confirming that the electron-hole pair recombination is reduced. From the point of view of pH, higher efficiencies are obtained in acidic solutions and the results are comparatively discussed considering the dye's ionic/neutral structure and the photocatalyst surface charge. The efficiency was calculated using UV-VIS spectrophotometer measurements of the solution and the thin films were

  14. TiO2 thin layers with controlled morphology for ETA (extremely thin absorber) solar cells

    The paper presents the synthesis process of dense and nanoporous TiO2 anatase films obtained via Spray Pyrolysis Deposition (SPD). The deposition of dense and nanostructured TiO2 films uses ethanol solutions of titaniumtetraisopropoxid and acetilacetonate. The influence of the precursor's concentration and deposition parameters (temperature, pressure of the carrier gas and distance of spraying) in tailoring the TiO2 morphology is presented. The films are tested via X-ray Diffraction and Scanning Electron Microscopy. The photoelectrical properties are tested by current-voltage (I-V) experiments in dark, at room temperature. According to the results, SPD proves to be a reliable technique in obtaining thin layers of TiO2 with controlled morphology

  15. Nb doping effect on TiO2-x films for bolometer applications

    Shin, Young Bong; Kumar Reddy, Y. Ashok; Kang, In-Ku; Lee, Hee Chul

    2016-04-01

    Nb-doped TiO2-x thin films were deposited using a 1 at% niobium doped titanium target by RF reactive magnetron sputtering at various oxygen partial pressures (pO2). The films appeared amorphous in the pO2 range of 4.4-4.7% with resistivity ranging from 0.39 Ω cm to 2.48 Ω cm. Compared to pure TiO2-x films, the resistivity of the Nb-doped TiO2-x films did not change sensitively with the oxygen partial pressure, indicating that the resistivity of the films can be accurately controlled. 1/f noise parameter of Nb-doped TiO2-x films were found to decrease largely while the measured temperature coefficient of resistance (TCR) of the films was still high. The obtained results indicate that Nb-doped TiO2-x films have great potential as an alternative bolometric material.

  16. Characterization of thin TiO2 films prepared by plasma enhanced chemical vapour deposition for optical and photocatalytic applications

    Thin titanium oxide films were deposited using a radio frequency (RF) plasma enhanced chemical vapour deposition method. Their optical properties and thickness were determined by means of ultraviolet-visible absorption spectrophotometry. Films of the optical parameters very close to those of titanium dioxide have been obtained at the high RF power input. Their optical quality is high enough to allow for their use in a construction of stack interference optical filters. At the same time, these materials exhibit strong photocatalytic effects. The results of structural analysis, carried out by Raman Shift Spectroscopy, show that the coatings posses amorphous structure. However, Raman spectra of the same films subjected to thermal annealing at 450 oC disclose an appearance of a crystalline form, namely that of anatase. Surface morphology of the films has also been characterized by Atomic Force Microscopy revealing granular, broccoli-like topography of the films.

  17. Fabrication of mechanically robust, self-cleaning and optically high-performance hybrid thin films by SiO2&TiO2 double-shelled hollow nanospheres

    Yao, Lin; He, Junhui; Geng, Zhi; Ren, Tingting

    2015-07-01

    Low-cost antireflection (AR) thin films on large-area optical surfaces are important for high-performance optical devices, display devices and photovoltaic cells. In the current work, SiO2&TiO2 double-shell hollow nanospheres (DSHNs) were designed, synthesized and utilized as building blocks for fabricating multifunctional AR thin films. By optimizing the porosity of SiO2&TiO2 DSHN and thin film structure, substrates with DSHN thin films attained transmittance as high as 99.4% and average transmittance up to 98.5% in the visible region. The nano-composite SiO2-TiO2 films exhibited intrinsic superhydrophilicity, anti-fogging and high photocatalytic activity. Tape peeling test, sponge washing test, and high temperature and moisture proof test showed favorable robustness and functional durability of the thin films, which make them extremely attractive for applications in lenses, photovoltaic cells and windows of high-rise buildings.Low-cost antireflection (AR) thin films on large-area optical surfaces are important for high-performance optical devices, display devices and photovoltaic cells. In the current work, SiO2&TiO2 double-shell hollow nanospheres (DSHNs) were designed, synthesized and utilized as building blocks for fabricating multifunctional AR thin films. By optimizing the porosity of SiO2&TiO2 DSHN and thin film structure, substrates with DSHN thin films attained transmittance as high as 99.4% and average transmittance up to 98.5% in the visible region. The nano-composite SiO2-TiO2 films exhibited intrinsic superhydrophilicity, anti-fogging and high photocatalytic activity. Tape peeling test, sponge washing test, and high temperature and moisture proof test showed favorable robustness and functional durability of the thin films, which make them extremely attractive for applications in lenses, photovoltaic cells and windows of high-rise buildings. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02467f

  18. Silver film on nanocrystalline TiO2 support: Photocatalytic and antimicrobial ability

    Highlights: • Simple photocatalytic rout for deposition of Ag on nanocrystalline TiO2 films. • High antibactericidal efficiency of deposited Ag on TiO2 support. • Improved photocatalytic performance of TiO2 films in the presence of deposited Ag. - Abstract: Nanocrystalline TiO2 films were prepared on glass slides by the dip coating technique using colloidal solutions consisting of 4.5 nm particles as a precursor. Photoirradiation of nanocrystalline TiO2 film modified with alanine that covalently binds to the surface of TiO2 and at the same time chelate silver ions induced formation of metallic silver film. Optical and morphological properties of thin silver films on nanocrystalline TiO2 support were studied by absorption spectroscopy and atomic force microscopy. Improvement of photocatalytic performance of nanocrystalline TiO2 films after deposition of silver was observed in degradation reaction of crystal violet. Antimicrobial ability of deposited silver films on nanocrystalline TiO2 support was tested in dark as a function of time against Escherichia coli, Staphylococcus aureus, and Candida albicans. The silver films ensured maximum cells reduction of both bacteria, while the fungi reduction reached satisfactory 98.45% after 24 h of contact

  19. Nanostructured columnar heterostructures of TiO2 and Cu2O enabled by a thin-film self-assembly approach: Potential for photovoltaics

    Polat, Ozgur [ORNL; Aytug, Tolga [ORNL; Lupini, Andrew R [ORNL; Paranthaman, Mariappan Parans [ORNL; Ertugrul, Memhet [Ataturk University; Bogorin, Daniela Florentina [ORNL; Meyer III, Harry M [ORNL; Wang, Wei [ORNL; Pennycook, Stephen J [ORNL; Christen, David K [ORNL

    2013-01-01

    Significant efforts are being devoted to the development of semiconductor thin film and nanostructured material architectures as components of solar energy harvesting and conversion devices. In particular, nanostructured assemblies with well-defined geometrical shapes have emerged as possible highly efficient and economically viable alternatives to planar junction thin film architectures , , , . However, fabrication of inorganic nanostructures generally requires complicated and multiple step processing techniques, making them less suitable for large-scale manufacturing. Hence, innovative cell architectures and materials processing schemes are essential to large-scale integration and practical viability in photovoltaic devices. Here we present here a new approach towards nanostructured thin film solar cells, by exploiting phase-separated self-assembly , . Through a single-step deposition by rf magnetron sputtering, we demonstrate growth of an epitaxial, composite film matrix formed as self-assembled, well ordered, phase segregated, and oriented p-n type interfacial nanopillars of Cu2O and TiO2. The composite films were structurally characterized to atomic resolution by a variety of analytical tools, and evaluated for preliminary optical properties using absorption measurements. We find nearly atomically distinct Cu2O-TiO2 interfaces (i.e. a p-n junction), and an absorption profile that captures a wide range of the solar spectrum extending from ultraviolet to visible wavelengths. This work opens a novel avenue for development of simple and cost-effective optically active thin film architectures, and offers promise for significantly increased photovoltaic device efficiencies using nanostructured cells that can be optimized for both incident light absorption and carrier collection.

  20. Influence of thickness on the structural properties of radio-frequency and direct-current magnetron sputtered TiO2 anatase thin films

    Thin films of TiO2 were deposited by reactive sputtering of a Ti target on unheated substrates and post-heated at 300 °C and 500 °C. They exhibit a granular structure. Direct current-sputtered films are amorphous as-deposited and crystallize (to pure anatase) only at 500 °C. Radio-frequency (rf)-sputtered films are already crystalline (pure anatase) as-deposited on unheated substrates. Above a thickness of 100 nm, the crystallite size, as deduced from the half-width of X-ray diffraction (XRD) peaks, is constant at 35 nm and decreases to zero when the thickness decreases to 25 nm. Below a thickness of 25 nm, the films are X-ray amorphous. Height and half-width of the XRD peaks of rf-sputtered films do not change upon post-heating at 300 or 500 °C. A larger lattice parameter ratio c/a is observed with respect to the bulk value that decreases with increasing film thickness and is about 1% larger for a film thickness larger than 100 nm. - Highlights: • Anatase films without the presence of rutile were grown on unheated substrates. • Radio-frequency sputtered films are crystalline as-deposited. • Direct-current sputtered films become crystalline only after annealing at 500 °C. • The crystallite size approaches zero when the film thickness approaches 25 nm. • There is an expansive strain in the crystallites along the c-axis

  1. Poly(ethylene-co-acrylic acid)-g-poly(ethylene glycol) graft copolymer templated synthesis of mesoporous TiO2 thin films for quasi-solid-state dye sensitized solar cells

    An amphiphilic graft copolymer, poly(ethylene-co-acrylic acid)-graft-poly(ethylene glycol) (PEAA-g-PEG), consisting of a PEAA backbone and PEG side chains was synthesized via an esterification reaction. 1H nuclear magnetic resonance and Fourier-transformed infrared analysis demonstrated esterification between carboxylic acid of PEAA and hydroxyl group of PEG. Small angle X-ray scattering results revealed that the crystalline domain spacing of PEAA increased from 11.3 to 12.8 nm upon using a more polar solvent with a higher affinity for poly(acrylic acid), while the crystalline domain spacing of PEAA disappeared with PEG grafting, indicating structural change to an amorphous state. Mesoporous TiO2 thin films were synthesized via a sol–gel reaction using PEAA-g-PEG graft copolymer as a structure-directing agent. The hydrophilically-preformed TiO2 nanoparticles were selectively confined in the hydrophilic PEG domains of the graft copolymer, and mesoporous TiO2 thin films were formed, as confirmed by scanning electron microscopy. The morphology of TiO2 films was tunable by varying the concentrations of polymer solutions and the amount of preformed TiO2. A quasi-solid-state dye-sensitized solar cell fabricated with PEAA-g-PEG templated TiO2 film exhibited an energy conversion efficiency of 3.8% at 100 mW/cm2, which was greater than that of commercially-available paste (2.6%) at a similar film thickness (3 μm). The improved performance was due to the larger surface area for high dye loading and organized structure with good interconnectivity. - Highlights: • Poly(ethylene-co-acrylic acid)-g-poly(ethylene glycol) (PEAA-g-PEG) graft copolymer is synthesized. • Amphiphilic PEAA-g-PEG acts as a structure directing agent. • Mesoporous TiO2 thin films are prepared by sol–gel reaction using PEAA-g-PEG template. • Efficiency of DSSC with templated TiO2 is greater than with commercial TiO2 paste

  2. TiO2 thin and thick films grown on Si/glass by sputtering of titanium targets in an RF inductively coupled plasma

    Valencia-Alvarado, R.; de la Piedad-Beneitez, A.; López-Callejas, R.; Mercado-Cabrera, A.; Peña-Eguiluz, R.; Muñoz-Castro, A. E.; Rodríguez-Méndez, B. G.; de la Rosa-Vázquez, J. M.

    2015-03-01

    TiO2 thin and thick films were deposited on silicon/glass substrates using RF inductive plasma in continuous wave. The films thickness, as well as phases control, is achieved with a gradual increase in temperature substrates varying supplied RF power or working gas pressure besides deposition time as well. The deposition conditions were: argon 80%/oxygen 20% carefully calibrated mixture of 2 to 7×10-2 mbar as working gas pressure range. Deposition time 0.5 to 5 hours, 500 or 600 W RF power at 13.56 MHz frequency and 242-345 °C substrates temperature range. The titanium dioxide deposited on the substrates is grown by sputtering of a titanium target negatively polarized at 3-5 kV DC situated 14 mm in front of such substrates. The plasma reactor is a simple Pyrex-like glass cylindrical vessel of 50 cm long and 20 cm in diameter. Using the before describe plasma parameters we obtained films only anatase and both anatase/rutile phases with stoichiometric different. The films were characterized by X-ray photoelectron spectroscopy (XPS), stylus profilometer, X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectroscopy.

  3. Enhancement of NMP Degradation Under UV Light by Nitrogen-Doped TiO2 Thin Films Using a Design of Experiment

    F. Arefi-Khonsari

    2011-01-01

    Full Text Available Doping nitrogen within TiO2 is an effective way to enhance visible light photocatalysis due to a direct electron excitation from the N2p states within the band gap. However, nitrogen doping is not always efficient for UV photocatalytic activity. Here, different structures of N-doped TiO2 (TiOxNy have been prepared by reactive RF (13.56 MHz magnetron sputtering. The morphological, optical, structural, and photocatalytic properties of the films have been studied in order to investigate the competitive effect of the morphology and the chemical composition on the efficiency of the photocatalytic activity. The variation of surface wettability of the film over time in the dark and under visible and UV irradiation was also studied. The reduction in wettability by dark storage can be explained by the adsorption of hydrocarbon contamination on the thin film’s surface. Additionally, from water contact angle experiments, it was found that these films developed hydrophilic properties upon UV and visible illumination. The photoinduced change in the contact angle of water was due to the removal of hydrocarbon contamination on the surface and also the photo-oxidation of the water droplet. Samples prepared at high pressure gave the best photocatalytic activity, even though the deposition rate was lower at higher pressures (lower film thicknesses, due to the high specific surface area and the optimal presence of TiOxNy crystals in the lattice. However, at low pressure, the TiN crystals became more predominant, and acted as recombination centers for the photo-generated charge carriers. A design of experiments was used in order to optimize the deposition parameters to have the best photocatalytic activity. The high photocatalytic activity under UV light was found to be due to the introduction of discrete energy levels within the band gap, the increased sample wettability, and the higher specific surface area. However, the post annealing process did not effect

  4. 多孔TiO2薄膜的制备及其光催化活性%Preparation and Photo-catalytic Activity of the Porous TiO2 Thin Films

    邹旭华; 齐世学; 刘雪梅; 于文娟; 安立敦

    2001-01-01

    The porous TiO2 thin films on both of carriers, glass sheet and glass fiber, are prepared from titanium alkoxide solution containing polyethylene glycol (PEG) by a dip-coating technique. The photo-catalytic degradation experiments show that methyl orange aqueous solution is efficiently decolorized in the presence of the porous TiO2 thin films by illumination with a high-pressure mercury lamp. The photo-catalytic activity of the TiO2 thin films is enhanced with the increase of the coating cycles or the PEG addition to the precursor solution. Under the same condition, the photo-catalytic activity of the porous TiO2 thin films on glass fiber is better than that of the porous TiO2 thin films using glass sheet as carriers.%采用溶胶-凝胶法在玻璃片和玻璃纤维两种基体上制备了多孔TiO2薄膜.对甲基橙水溶液的光催化降解实验表明:在一定范围内,随着TiO2镀层层数的增加,薄膜的光催化活性增强;且相同条件下,以玻璃纤维为基体的薄膜的光催化活性明显优于以玻璃片为基体的薄膜的活性.

  5. Photocatalytic TiO2 thin films for air cleaning : Effect of facet orientation, chemical functionalization, and reaction conditions

    Stefanov, Bozhidar

    2015-01-01

    Poor indoor air quality is a source of adverse health effects. TiO2 coatings deposited on well-illuminated surfaces, such as window panes, can be used to fully mineralize indoor air pollutants by photocatalysis. In such applications it is important to ensure stable photocatalytic activity for a wide range of operating conditions, such as relative humidity and temperature, and to avoid deactivation of the catalyst. In this thesis photocatalytic removal of the indoor-pollutant acetaldehyde (CH3...

  6. Combination of TiO2-Film Photocatalysis and Ultrafiltration to Treat Wastewater

    Shu-Hai You

    2013-01-01

    Full Text Available In this study, a combination of TiO2-film photocatalysis reactor and ultrafiltration was used treat the secondary effluent from the manufacturing of thin film transistor-liquid crystal display (TFT-LCD. TiO2 particles, as a photocatalyst, were immobilized on silica glass to form TiO2-film by the sol-gel and dip coating methods. TiO2-film photocatalysis was done within three parameters, including number of coating times of TiO2-film, wavelengths of UV light source, and operating time. During ultrafiltration, the operating pressure and feed water temperature were controlled at 300 KN/m2 and 25°C, respectively. It was found that TiO2-film photocatalysis followed by ultrafiltration increased the removal of total organic carbon (TOC to 47.13% and 49.94% for 5 KDa and 10 KDa membranes, respectively. It was also found that the process increased the permeate flux rate (ca 23% for 10 KDa membrane after 6 hours of operation, since some larger organic matter had been broken into small organic matter and some small organic matter had been mineralized into CO2 following TiO2-film photocatalysis. Therefore, combining TiO2-film photocatalysis reactor and ultrafiltration can improve organic wastewater quality and increase the permeate flux of ultrafiltration membrane, which may enhance the recycling and reuse of wastewater.

  7. Photo-electrochemical studies of chemically deposited nanocrystalline meso-porous n-type TiO2 thin films for dye-sensitized solar cell (DSSC) using simple synthesized azo dye

    Ezema, C. G.; Nwanya, A. C.; Ezema, B. E.; Patil, B. H.; Bulakhe, R. N.; Ukoha, P. O.; Lokhande, C. D.; Maaza, Malik; Ezema, Fabian I.

    2016-04-01

    Nanocrystalline titanium dioxide (TiO2) thin films were deposited by successive ionic layer adsorption and reaction method onto fluorine doped tin oxide coated glass substrate at room temperature (300 K). Titanium trichloride and sodium hydroxide were used as cationic and anionic sources, respectively. The as-deposited and annealed films were characterized for structural, morphological, optical, electrical and wettability properties. The photoelectrochemical study of TiO2 sensitized with a laboratory synthesized organic dye (azo) was evaluated in the polyiodide electrolyte at 40 mW cm-2 light illumination intensity. The photovoltaic characteristics show a fill factor of 0.24 and solar conversion efficiency value of 0.032 % for a TiO2 thickness of 0.96 µm as compared to efficiency of 0.014 % for rose Bengal of the same thickness.

  8. Surface characterisation and photocatalytic performance of N-doped TiO2 thin films deposited onto 200 nm pore size alumina membranes by sol–gel methods

    Membrane filtration is employed for water treatment and wastewater reclamation purposes, but membranes alone are unable to remove pollutant molecules and certain pathogens. Photocatalytically active N-doped TiO2 coatings have been deposited by sol–gel onto 200 nm pore size alumina membranes for water treatment applications using two different methods, via pipette droplets or spiral bar applicator. The uncoated and coated membranes were characterised by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray spectrometry (EDX). Both coatings showed the presence of N-doped anatase, with a surface coverage between 84 and 92%, and nitrogen concentration (predominantly interstitial) of 0.9 at.%. The spiral bar applicator deposited coatings exhibit a thicker mud-cracked surface layer with limited penetration of the porous membrane, whilst the pipette deposited coatings have mostly penetrated into the bulk of the membrane and a thinner layer is present at the surface. The photocatalytic activity (PCA), measured through the degradation of carbamazepine (CBZ), under irradiation of a solar simulator was 58.6% for the pipette coating and 63.3% for the spiral bar coating. These photocatalytically active N-doped sol–gel coated membranes offer strong potential in forming the fundamental basis of a sunlight based water treatment system. - Highlights: • Sol gel N-doped TiO2 thin films were deposited on 200 nm pore size Al2O3 membranes. • Two sol–gel methods have been compared – pipette drop and spiral bar deposition. • The coatings showed a similar microstructure and composition but different morphology. • The PCA (degradation of carbamazepine) was ∼60% for both sol–gel coatings. • The coated membranes are promising for use in a membrane based water treatment system

  9. Porous (001-faceted anatase TiO2 nanorice thin film for efficient dye-sensitized solar cell

    Shah Athar Ali

    2016-01-01

    Full Text Available Anatase TiO2 structures with nanorice-like morphology and high exposure of (001 facet has been successfully synthesized on an ITO surface using ammonium Hexafluoro Titanate and Hexamethylenetetramine as precursor and capping agent, respectively, under a microwave-assisted liquid-phase deposition method. These anatase TiO2 nanoparticles were prepared within five minutes of reaction time by utilizing an inverter microwave system at a normal atmospheric pressure. The morphology and the size (approximately from 6 to 70 nm of these nanostructures can be controlled. Homogenous, porous, 5.64 ± 0.002 μm thick layer of spongy-nanorice with facets (101 and (001 was grown on ITO substrate and used as a photo-anode in a dye-sensitized solar cell (DSSC. This solar cell device has emerged out with 4.05 ± 0.10% power conversion efficiency (PCE and 72% of incident photon-to-current efficiency (IPCE under AM1.5 G illumination.

  10. Structural, magnetic and optical properties of Ni-doped TiO2 thin films deposited on silicon(1 0 0) substrates by sol–gel process

    Highlights: •Ni doping decreases the activation energy for the anatase-to-rutile transformation. •With increasing Ni content, the reversible ferromagnetism is found. •Sharp decrease of the EOBG at low Ni content is mainly related to phase composition. -- Abstract: Ni-doped TiO2 films were deposited on Si(1 0 0) substrates by sol–gel technique. X-ray photoelectron spectroscopy analysis suggests that the valence of Ni ion is in +2 and oxygen vacancies increase with increasing Ni content. X-ray diffraction measurements indicate that Ni doping catalyzes the anatase-to-rutile transformation (ART) of TiO2 films, which is due to the decrease of the ART activation energy. The reversible ferromagnetism of the samples with Ni fraction is found, which is due to an anatase-to-rutile junction destroying an F-center bound magnetic polaron. Optical properties of Ni-doped TiO2 films were studied by the ellipsometric spectra. With increasing Ni content, the optical band gap of TiO2 films is decreased from 3.56 to 3.34 eV, which may be related to phase composition and impurity band

  11. Thin films composed of Ag nanoclusters dispersed in TiO2: Influence of composition and thermal annealing on the microstructure and physical responses

    Borges, J.; Rodrigues, M. S.; Lopes, C.; Costa, D.; Couto, F. M.; Kubart, T.; Martins, B.; Duarte, N.; Dias, J. P.; Cavaleiro, A.; Polcar, T.; Macedo, F.; Vaz, F.

    2015-12-01

    Noble metal powders containing gold and silver have been used for many centuries, providing different colours in the windows of the medieval cathedrals and in ancient Roman glasses. Nowadays, the interest in nanocomposite materials containing noble nanoparticles embedded in dielectric matrices is related with their potential use for a wide range of advanced technological applications. They have been proposed for environmental and biological sensing, tailoring colour of functional coatings, or for surface enhanced Raman spectroscopy. Most of these applications rely on the so-called localised surface plasmon resonance absorption, which is governed by the type of the noble metal nanoparticles, their distribution, size and shape and as well as of the dielectric characteristics of the host matrix. The aim of this work is to study the influence of the composition and thermal annealing on the morphological and structural changes of thin films composed of Ag metal clusters embedded in a dielectric TiO2 matrix. Since changes in size, shape and distribution of the clusters are fundamental parameters for tailoring the properties of plasmonic materials, a set of films with different Ag concentrations was prepared. The optical properties and the thermal behaviour of the films were correlated with the structural and morphological changes promoted by annealing. The films were deposited by DC magnetron sputtering and in order to promote the clustering of the Ag nanoparticles the as-deposited samples were subjected to an in-air annealing protocol. It was demonstrated that the clustering of metallic Ag affects the optical response spectrum and the thermal behaviour of the films.

  12. Effect of firing atmosphere and bottom electrode on resistive switching mode in TiO2 thin films

    Sol–gel deposited Ag/TiO2/Pt tri-layers exhibit unipolar resistive switching (URS) with a negative turn-on voltage when fired in air. Variation in both the turn-on voltage and the on-state current at turn-off threshold is observed in successive current–voltage (I–V) measurements. Based on the same composition and processing flow, bipolar resistive switching (BRS) showing positive turn-on voltage by contrast is obtained by applying two alternative procedures: one procedure under oxygen ambience and another one in which indium–tin oxide is used as the bottom electrode. Conduction mechanisms induced by reduction/oxidation reactions explain how firing ambient and bottom electrode affect the switching mode, as well as the distinct turn-on voltage polarity. URS and BRS are related to the amount of ambient oxygen and the arrangement of internal oxygen vacancy, thus determining whether the direction-independent thermochemical heating or polarity-dependent electrochemical oxidation near the anode interface is responsible for the filament rupture. Additionally, the space-charge-limited transport is analyzed to examine how URS and BRS-activated samples significantly differ from each other. Importantly, the temperature-dependent I–V data helps to elucidate the dominant carrier behavior in the regime of low and high electric field. - Highlights: ► Resistive switching mode and polarity in TiO2 were discussed. ► Amounts of non-lattice oxygen were compared. ► Three sample sets of TiO2 were prepared and investigated

  13. Solvothermal synthesis of nanoporous TiO2: the impact on thin-film composite membranes for engineered osmosis application

    Emadzadeh, D.; Ghanbari, M.; Lau, W. J.; Rahbari-Sisakht, M.; Matsuura, T.; Ismail, A. F.; Kruczek, B.

    2016-08-01

    In the current study, the impact of self-synthesized nanoporous titanium oxide (NT) on the morphology, performance and fouling of a polyamide (PA) thin-film composite (TFC) membrane was investigated when the membrane was applied for engineering osmosis (EO). The nanoporous structure and the spindle-like shape of NT were revealed through transmission electron microscopy (TEM), while the AATPS modification of NT was verified by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The results of x-ray photoelectron spectroscopy (XPS) and x-ray diffraction (XRD) confirmed the presence of modified NT (mNT) in the PA dense active layer of the TFC membrane. The outgrowth of the ‘leaf-like’ structure, upon mNT loading, at the surface of the PA layer was observed by field-emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The TFC membrane prepared with 0.05 wt% mNT loading in the organic phase showed the water flux of 26.4 l m‑2 h‑1 when tested in the forward osmosis (FO) mode using 0.5M and 10 mM NaCl solution as the draw and feed solution, respectively. Moreover, the TFC-mNT membrane also demonstrated an intensified antifouling property against organic foulant during FO application and it was possible to retrieve the initial water flux almost completely with a simple water-rinsing process.

  14. Investigation of a broadband TiO2/SiO2 optical thin-film filter for hybrid solar power systems

    Highlights: ► We present a new optical filter to get optimal performance of PV power system. ► The experimental results of the filter fabrication match well with numerical design. ► The measured results of a typical Si cell show efficiency increase using the filter. ► A proposed model for hybrid PV–TEG system demonstrates the benefits of the filter. -- Abstract: Using the technology of spectral selectivity to integrate different solar power generators in a hybrid system is a feasible way to improve the optical-electric efficiency. This paper presents an 82-layer broadband optical interference thin-film filter matching with crystalline silicon photovoltaic cells, which using TiO2 and SiO2 as fabrication materials and can be used in hybrid solar power systems like photovoltaic–thermoelectric generator (PV–TEG) systems. The design, optimization and fabrication process of the filter is described, high reflectance from 400 nm to 1100 nm as well as high transmittance from 1100 nm to 2500 nm over the broadband of solar spectrum are obtained. The classical electron beam evaporation plant is used to fabricate the filter. Four different incidence angles’ optical performances of the sample filter are measured which agree well with the numerical simulation results. The electrical characteristics of a typical Silicon photovoltaic cell using the fabricated sample filter are measured. An average efficiency increase of 3.24% for the solar cell with respect to the solar energy it receives can be obtained due to the filter. A calculation model for a hybrid PV–TEG system using this thin-film filter is proposed and the benefits of the filter for hybrid solar power systems are demonstrated.

  15. Nanostructured TiO2 Films Attached CdSe QDs Toward Enhanced Photoelectrochemical Performance.

    Du, Yingying; Yang, Ping; Liu, Yunshi; Zhao, Jie; He, Haiyan; Miao, Yanping

    2016-06-01

    TiO2 films consisted of small nanoparticles were fabricated via a spinning coating method on fluorine doped in tin oxide (FTO) slide glass. After calcination, the films were subsequently sensitized by CdSe quantum dots (QDs) using mercaptopropionic acid (MPA) as a bifunctional surface modifier. Upon UV light irradiation, CdSe QDs inject electrons into TiO2 nanoparticles, thus resulting in the generation of photocurrent in QD-sensitized solar cell. The results indicate that TiO2 films sensitized by CdSe QDs have achieved 1.5-fold enhancement in photocurrent compared with pure TiO2 films, indicating that CdSe QDs can improve the photocurrent by promoting the separation of photoinduced charge carriers. In addition, the photocurrent enhances as the thickness of TiO2 films increased. Such improved photoelectrochemical performance is ascribed to the basis of improved interfacial charge transport of the TiO2-CdSe composite films. Combining QDs on TiO2 thin films is a promising and effective way to enhance the photoelectrochemical performance, which is important in QD-sensitized solar cell application. PMID:27427714

  16. Preparation and characterization of WO3 nanoparticles, WO3/TiO2 core/shell nanocomposites and PEDOT:PSS/WO3 composite thin films for photocatalytic and electrochromic applications

    Boyadjiev, Stefan I.; Santos, Gustavo dos Lopes; Szżcs, Júlia; Szilágyi, Imre M.

    2016-03-01

    In this study, monoclinic WO3 nanoparticles were obtained by thermal decomposition of (NH4)xWO3 in air at 600 °C. On them by atomic layer deposition (ALD) TiO2 films were deposited, and thus core/shell WO3/TiO2 nanocomposites were prepared. We prepared composites of WO3 nanoparticles with conductive polymer as PEDOT:PSS, and deposited thin films of them on glass and ITO substrates by spin coating. The formation, morphology, composition and structure of the as-prepared pure and composite nanoparticles, as well thin films, were studied by TEM, SEM-EDX and XRD. The photocatalytic activity of both the WO3 and core/shell WO3/TiO2 nanoparticles was studied by decomposing methyl orange in aqueous solution under UV light irradiation. Cyclic voltammetry measurements were performed on the composite PEDOT:PSS/WO3 thin films, and the coloring and bleaching states were studied.

  17. The Effect of SiO2 Additive on Super-hydrophilic Property of TiO2-SiO2 Thin Film by Sol-gel Method

    2001-01-01

    TiO2-SiO2 thin films have been prepared on slide glass substrates by sol-gel method, and the effect of SiO2 additive on photo-generated hydrophilicity of TiO2 thin film was investigated by measuring the contact angle of water, the microstructure, the transmittance, the photocatalytic activity and the specific surface area. The results showed that 10mol% of SiO2 additive was the most effective for decreasing contact angle of water. The SiO2 additive of less than 30mol% has a suppressive effect on the crystal growth of anatase in calcinations, resulting in a large surface area. Consequently, the super-hydrophilicity was improved.

  18. Effect of annealing treatment on electrical and optical properties of Nb doped TiO2 thin films as a TCO prepared by sol–gel spin coating method

    Highlights: • We synthesized Nb doped TiO2 thin films using a simple sol–gel spin coating method. • The effect of O2 in annealing process was studied on conductivity of TNO thin films. • A comparison between O2 and Burstein–Moss effect on optical band gap has been studied. - Abstract: Anatase niobium doped TiO2 thin films (Ti0.94Nb0.06O2) were prepared on quartz substrates by sol–gel spin coating technique and various initial concentrations ([Ti + Nb] in the solution) of 0.1 M and 0.4 M. All the films dried at 100 °C and then the annealing treatment performed by three different procedures. The influence of different annealing processes and total metal concentrations was studied on crystallinity, transparency, conductivity and morphology of thin films by XRD, EDX, FT-IR and UV–vis transmittance spectroscopy, four point probe, AFM and SEM images. It was found that two-step annealing procedure under vacuum is a more proper way to increase the conductivity of TNO thin films compared to one-step annealing process. Two-step method exhibited the minimum resistivity of 4.4 Ω cm and the transparency of about 50% in the visible region with 36 nm thickness

  19. Effect of hot-filament annealing in a hydrogen atmosphere on the electrical and structural properties of Nb-doped TiO2 sputtered thin films

    In this work Nb-doped TiO2 thin films were deposited by d.c.-pulsed reactive magnetron sputtering at 500 °C from a composite target with weight fractions of 96% Ti and 4% Nb, using oxygen as reactive gas. In order to enhance the conductive properties, the as-deposited samples were treated in vacuum with atomic hydrogen at a substrate temperature of 500 °C. The atomic hydrogen flow was generated by a hot filament, inside a high-vacuum chemical vapour deposition reactor, at a temperature of 1750 °C. In order to optimise the hydrogen hot-wire treatments, the H2 pressure was varied between 1.3 and 67 Pa, the treatment time was monitored between 1 and 5 min and the hot-filament current was changed between 12 and 17 A. Dark conductivity was measured as a function of temperature and its value at room temperature was extrapolated and used to assess the effect of the hydrogen annealing on the charge transport properties. A two-order of magnitude increase in dark conductivity was typically observed for optimised hydrogen treatments (10 Pa), when varying the hydrogen pressure, resulting in a minimum resistivity of ∼ 3 × 10−3 Ω cm at room temperature. The maximum amount of atomic H incorporation in oxygen vacancies was determined to be ∼ 5.7 at.%. Carrier mobility and resistivity were also investigated using Hall effect measurements. Correlations between structural and electrical properties and the hydrogen treatment conditions are discussed. The purpose of these films is to provide a transparent and conductive front contact layer for a-Si based photovoltaics, with a refractive index that better matches that of single and tandem solar cell structures. This can be achieved by an appropriate incorporation of a very small amount of cationic doping (Nb5+) into the titanium dioxide lattice.

  20. Effect of substrate temperature on the arrangement of ultra-thin TiO2 films grown by a dc-magnetron sputtering deposition

    TiO2 films with a thickness between 3 and 10 nm are obtained by a dc-magnetron sputtering deposition in the reactive gas atmosphere and the properties of the films are investigated by the Raman spectroscopy, X-ray photoelectron spectroscopy and scanning probe microscopy. An influence of the deposition temperature and the post-growth annealing on the properties of the films is studied at the temperatures from 375 to 650 K. It is experimentally demonstrated that the crystalline structure can be identified by the Raman spectroscopy in the films with the thickness higher than 9 nm and annealed in the oxygen rich atmosphere for at least 2 h at about 630 K. It is proved that the changes in the film structure are not related to the changes in the chemical composition, the Ti state, and the stoichiometry of the films. Basing on the fractal analysis of topographical images, it is shown that the structural changes can be associated with the changes in the fractal dimension. These changes can be a quantitative characteristic of the structure for the films thinner than 10 nm. - Highlights: • TiO2 films (< 10 nm) with crystalline anatase and amorphous grains were investigated. • Amounts of the crystalline and amorphous grains depend on the substrate temperature. • Fractal dimension is used as an indicator of a crystalline–amorphous grain mixture

  1. Superhydrophilic and Wetting Behavior of TiO2 Films and their Surface Morphologies

    TiO2 films, showing superhydrophilic behavior, are prepared by electron beam evaporation. Atomic force microscopy and the contact angle measurement were performed to characterize the morphology and wetting behavior of the TiO2 films. Most studies attribute the wetting behavior of TiO2 surfaces to their physical characteristics rather than surface chemistry. These physical characteristics include surface morphology, roughness, and agglomerate size. We arrange these parameters in order of effectiveness. Surface morphologies are demonstrated to be the most important. TiO2 films with particular morphologies show superhydrophilic behavior without external stimuli, and these thin films also show stable anti-contamination properties during cyclical wetting and drying. (cross-disciplinary physics and related areas of science and technology)

  2. Size dependent electron transfer from CdTe quantum dots linked to TiO2 thin films in quantum dot sensitized solar cells

    In this present study, we demonstrate the size dependent charge transfer from CdTe quantum dots (QDs) into TiO2 substrate and relate this charge transfer to the actual behavior of a CdTe sensitized solar cell. CdTe QDs was synthesized using mercaptopropionic acid as the capping agent. The conduction band offset for TiO2 and CdTe QDs indicates thermodynamically favorable band edge positions for smaller QDs for the electron-transfer at the QD–TiO2 interface. Time-resolved emission studies were carried out for CdTe QD on glass and CdTe QD on TiO2 substrates. Results on the quenching of QD luminescence, which relates to the transfer kinetics of electrons from the QD to the TiO2 film, showed that at the smaller QD sizes the transfer kinetics are much more rapid than at the larger sizes. I–V characteristics of quantum dot sensitized solar cells (QDSSC) with different sized QDs were also investigated indicating higher current densities at smaller QD sizes consistent with the charge transfer results. The maximum injection rate constant and photocurrent were obtained for 2.5 nm CdTe QDs. We have been able to construct a solar cell with reasonable characteristics (Voc = 0.8 V, Jsc = 1 mA cm−2, FF = 60%, η = 0.5%). - Highlights: • Size dependant charge transfer from quantum dots to TiO2. • Smaller quantum dot sizes promote higher current densities in solar cell. • Smaller quantum dots have favorable band edge positions and transport kinetics

  3. 工艺参数对磁控溅射制备TiO2薄膜结晶性的影响%Effects of Process Parameters on Crystalline TiO2 Thin Films Prepared by Magnetron Sputtering

    张盼盼; 丁龙先; 张帅拓

    2015-01-01

    目的:探究TiO2薄膜结晶性与工艺参数之间的规律。方法采用直流反应磁控溅射法,改变工艺条件(样品位置、溅射功率、氧气分压、是否开转架、沉积温度以及是否退火),在普通载玻片基底上制备TiO2薄膜,并利用XRD和SEM对不同工艺参数下获得的TiO2薄膜进行分析。结果在靶基距固定的情况下,仅改变样品悬挂的上下位置时,薄膜的结晶性差别不大。随着溅射功率在一定范围内增大,薄膜的结晶性越来越好(趋于锐钛矿晶型)。与氧气分压为5%时相比,10%时的薄膜结晶性更优;与开转架时相比,不开转架时薄膜的结晶性更优。沉积温度在300,350℃两者之间变化时,对薄膜的结晶性影响不大。退火后薄膜的结晶性优于未退火薄膜。结论样品位置、沉积温度对于TiO2薄膜的结晶性影响不大;氧气分压、是否开转架对TiO2薄膜的结晶性有一定影响;溅射功率、退火与否对TiO2薄膜的结晶性影响较大,并且退火后出现金红石相。%ABSTRACT:Objective To explore the pattern between the crystallization of TiO2 thin films and the process parameters. Methods The process conditions ( the position of the sample, sputtering power, oxygen partial pressure, the bogie, deposition temperature and annealing) were modified by the DC reactive magnetron sputtering method to prepare TiO2 thin films on the common slide glass substrate. TiO2 thin films under different process parameters were analyzed by XRD and SEM. Results In the case of fixed target-substrate distance, simply changing the sample suspension position had little influence on thin-film crystalline. As the sputtering power increased within a certain range, the film crystalline became better and better ( tending to anatase crystal) . Crystalline of the thin film whose oxygen partial pressure was 10% was better than that whose pressure was 5%. The thin film crystalline was superi-or when the turntable was

  4. Layer-by-layer assembling TiO2 film from anatase TiO2 sols as the photoelectrochemical sensor for the determination of chemical oxygen demand

    Highlights: ► The anatase TiO2 sols containing 5 nm nanocrystals were prepared by the peptization of trifluoroacetic acid for the first time. ► The anatase TiO2 sols were used to prepare TiO2 thin films, and the films were employed as a photo-electrochemical sensor for the determination of chemical oxygen demand (COD). ► The COD detection limit of 1 mg L−1 with a working range of 0–130 mg L−1 was achieved with the layer-by-layer TiO2 films. - Abstract: Anatase TiO2 sols containing ultrafine TiO2 crystallites (ca. 5 nm) were prepared by the peptization of amorphous precipitates in trifluoroacetic acid (TFA) solution. The crystallite size of TiO2 in the sols was tuned by the subsequently hydrothermal treatment. The as-prepared TiO2 nanoparticles were characterized by X-ray diffraction, Raman spectrometry, UV–vis absorption spectrometry and transmission electron microscopy. The positive charged nanoparticles in the sol with the Ti/TFA molar ratio of 1:8 and the poly(styrene sulfonic acid) sodium salt solution were used to prepare TiO2 thin films by a layer-by-layer (LBL) self assembly method. Since the compact structure of the LBL thin films was good for the electronic transport, the TiO2 LBL thin films were introduced to be working electrodes in three-electrode photoelectrochemical cells. The 15-layer TiO2 thin film electrode showed a high photoelectrochemical property and it was employed as a sensor for the chemical oxygen demand. The detection limit of 1 mg L−1 with a working range of 0–130 mg L−1 was achieved. The relative standard deviation was 3.56% for 30 repetitive detections of 200 μM glucose with the theoretical COD value of 38.4 mg L−1 COD.

  5. Characterization of Sol-gel-derived TiO2 and TiO2-SiO2 Films for Biomedical Applications

    Jingxiao LIU; Fei SHI; Dazhi YANG

    2004-01-01

    In order to improve the corrosion resistance and biocompatibility of NiTi surgical alloy, TiO2 and TiO2-SiO2 thin films were prepared by sol-gel method. The surface characteristics of the film, which include surface composition, microstructure and surface morphology, were studied by X-ray diffraction (XRD), atomic force microscopy (AFM) and X-ray photoelectron spectra (XPS), respectively. A scratching test was used to assess the interface adhesive strength between the film and substrate. The corrosion resistance of NiTi alloy coated with oxide films were studied by anodic polarization curves measurement in biological solution. Additionally, a preliminary study of the in vitro bioactivity of the films was conducted. The results indicated that TiO2 and TiO2-SiO2 (Ti/Si=4:1) films have higher electrochemical corrosion resistance and can be used as protective layers on NiTi alloy. In addition, TiO2-SiO2 composite films have better bioactivity than TiO2 film.

  6. Comparison of photocatalytic activity of TiO2 film doped nonuniformly by Mn and Zn

    XU Wei; LI Xin-jun; ZHENG Shao-jian; WANG Jun-gang; XU Zhong-kui

    2005-01-01

    The thin films of TiO2, doped by Mn or Zn with nonuniform distribution, were prepared by sol-gel method under process control. The actinic absorption of the catalyst thin films was evaluated by UV-vis spectrophotometry. And the activity of the photocatalyst was evaluated by photocatalytic degradation kinetics of aqueous methyl orange under UV radiation. The results show that the photocatalytic activity of the TiO2 thin film can be evidently enhanced by Mn non-uniformly doping in the bottom layer and can be decreased by Mn doping in the surface layer.The activity of TiO2 thin film can be evidently enhanced by Zn non-uniform doping in either the bottom or the surface layer. But the activity of TiO2 is less affected by uniformly Zn doping. The different mechanisms for enhanced photocatalytic activity of Mn or Zn non-uniformly doped titanium dioxide film were discussed in terms of the separation of photon-generated carrier in the TiO2 films.

  7. An oblique angle radio frequency sputtering method to fabricate nanoporous hydrophobic TiO2 film

    In this work, we investigate growth of ordered arrays of amorphous TiO2 nano-columns by using radio frequency sputter deposition technique. The as-prepared thin films were characterized by atomic force microscopy, field emission scanning electron microscopy, X-ray diffraction, and ultraviolet–visible spectroscopy. The nano-columnar films are found to be porous in nature which results from glancing angle sputter deposition. In fact, porosity has a linear relationship with increasing deposition angle. Reflectance of the thin films is also studied as a function of porosity. In addition, contact angle measurements demonstrate the roughness dependent transition from a hydrophilic to a hydrophobic TiO2 surface. - Highlights: • Porous nano-columnar array of TiO2 thin film • Transition of hydrophilic to hydrophobic surface • Correlation of optical property with porosity

  8. TiO2 and Fe-Doped TiO2 Thin Layers

    Dragounová, Pavlína; Morozová, Magdalena; Šolcová, Olga

    Bratislava: AXIMA Graphics Design & Printing Services, 2014, s. 26 ISBN 978-80-89475-13-1. [International Conference of Slovak Society of Chemical Engineering /41./. Tatranské Matliare (SK), 26.05.2014-30.05.2014] R&D Projects: GA TA ČR TA01020804 Grant ostatní: NATO(US) SPS984398 Institutional support: RVO:67985858 Keywords : sol-gel * TiO2 * Fe-TiO2 thin layers Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  9. Influence of a TiO2 buffer layer on the magnetic properties of anatase Co:TiO2 thin films

    Our study addresses the influence of a TiO2 buffer layer on the morphological, structural, and magnetic properties of Co:TiO2 films grown on (001) SrTiO3 substrates by RF sputtering. We demonstrate that a direct correlation exist between the morphology, the Co heterogeneity, and the magnetic properties measured in the films. Correlated analysis by cross section transmission electron microscopy, energy dispersive x-ray, and x-ray photoemission spectroscopy reveals that the Co is not uniformly distributed in the film but concentrated in the surface clusters. Atomic force microscopy analysis illustrates that the unbuffered films present a large density of surface clusters. These clusters are not metallic Co but Co rich TiO2 anatase phase and they are accompanied by structural defects in the film: dislocations, small angle grain boundaries. Magnetometry analysis shows that the unbuffered films have a net ferromagnetic behavior, while in the buffered ones the ferromagnetism is quenched. Therefore, we conclude that the magnetism in unbuffered samples is related to the surface clusters and seems to have an extrinsic nature.

  10. Low-temperature electrodeposition approach leading to robust mesoscopic anatase TiO2 films

    Patra, Snehangshu; Andriamiadamanana, Christian; Tulodziecki, Michal; Davoisne, Carine; Taberna, Pierre-Louis; Sauvage, Frédéric

    2016-02-01

    Anatase TiO2, a wide bandgap semiconductor, likely the most worldwide studied inorganic material for many practical applications, offers unequal characteristics for applications in photocatalysis and sun energy conversion. However, the lack of controllable, cost-effective methods for scalable fabrication of homogeneous thin films of anatase TiO2 at low temperatures (ie. cell technology translates into a remarkable power conversion efficiency of 7.2% under A.M.1.5G conditions.

  11. Sm掺杂对TiO2薄膜结构和电致变色性能的影响%Effect of Sm doping on structure and electrochromic properties of TiO2 thin film

    牛微; 毕孝国; 王刚; 孙旭东

    2014-01-01

    Sm doped TiO2 thin films were prepared by sol-gel methods with butyltitanate and samarium nitrate as main components.The Sm doping molar ratios are 0,2%,5%,10% and 20%.Structural,thermogravimet-ric and electrochemical properties were investigated by XRD,TG-DTA,cyclic voltammetry curves(CV)and ul-traviolet visible spectroscopy.The result indicates that the Sm doped TiO2 thin film has higher amorphous de-gree.When the heat processing temperature was at 250 ℃,Sm doped TiO2 thin film has good ion storage ca-pacity and cyclic reversibility.When the doped amount of Sm was at 5%,the peak current of thin film reaches its maximum value with most powerful charge storage capability,injected charge density at 13.35 mC/cm2 ,and cyclic reversibility K value at 0.92.Sm doped TiO2 thin film has good transparency in the visible light range and transmittance was 70%-80%.This would be used as ion storage material in electrochromic glass.%以钛酸四丁酯和硝酸钐为主要原料,采用溶胶-凝胶法制备了 Sm 掺杂 TiO2薄膜。Sm 掺杂的摩尔分数分别为0,2%,5%,10%和20%。采用XRD和TG-DTA表征了薄膜的结构和热重特性,使用电化学工作站和紫外-可见分光光度计研究了薄膜的电致变色性能。结果表明,Sm掺杂使得 TiO2薄膜具有更高的无定形程度。250℃热处理的 Sm 掺杂 TiO2薄膜具有较高的电荷存储能力和循环可逆性。Sm 掺杂量为5%时,薄膜的峰值电流最大,电荷存储能力最强,注入电荷密度为13.35 mC/cm2,循环可逆性 K 值为0.92。Sm掺杂 TiO2薄膜在可见光范围内具有较好的光学透明度,透光率在70%~80%。适于用作电致变色器件的离子存储层。

  12. Worm-like mesoporous TiO2 thin films templated using comb copolymer for dye-sensitized solar cells with polymer electrolyte

    Lee, Jae Hun; Park, Cheol Hun; Jung, Jung Pyo; Kim, Jong Hak

    2015-12-01

    A comb copolymer consisting of hydrophobic poly(2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl] ethyl methacrylate) (PBEM) and hydrophilic poly(oxyethylene methacrylate) (POEM) is synthesized via one-pot free radical polymerization. The PBEM-POEM comb copolymer is used as an agent to direct the structure toward one consisting of worm-like mesoporous TiO2 (WM-TiO2) films. The selective, preferential interaction between the titania precursor and the hydrophilic POEM chains is responsible for the formation of a well-organized worm-like mesostructure. The morphology of the WM-TiO2 films is characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). In particular, the effects of film thickness on the optical and electrochemical properties are systematically investigated. The introduction of the WM-TiO2 layer between the nanocrystalline TiO2 (NC-TiO2) layer and fluorine-doped tin oxide (FTO) glass results in increased transmittance of visible light due to an antireflective property, decreased interfacial resistance and suppressed charge recombination at the interfaces of NC-TiO2/FTO glass. As a result, the photovoltaic conversion efficiency of the dye-sensitized solar cell (DSSC) with a polymer electrolyte is improved from 5.3% to 6.6% at an optimum film thickness (310 nm). The obtained efficiency represents a higher efficiency for the N719-based DSSC with a solvent-free, polymer electrolyte.

  13. 金属离子掺杂纳米TiO2薄膜光阳极的性能研究%Studies on optical anode properties of the TiO2 thin film doped with metal ions

    容齐坤; 曾凡菊; 李玲

    2011-01-01

    采用溶胶-凝胶法在玻璃衬底上制备TiO2多孔薄膜,掺杂不同功函数的金属离子制备M-TiO2纳米薄膜电极,XRD、AFM,UV-Vis检测M-TiO2结构、形貌和性能.结果表明:掺杂摩尔分数2%的金属离子没有改变TiO2的晶格结构,但其吸收峰在可见光区都发生明显的红移,禁带宽度降低,掺杂后的M-TiO2电极比没有掺杂的TiO2电极更适合做染料敏化太阳能电池的光阳极,特别是Mg-TiO2和Ni-TiO2电极的禁带宽度分别达到2.19 eV和2.09 eV,与非晶硅的禁带宽度1.70 ev相近.%TiO2 thin films and TiO2 thin films doped with different performance function metal ions(M-TiO2) were prepared on glass substrates by sol-gel method. The structure, morphology and properties of TiO2 thin films were investigated by XRD, AFM and UV-Vis spectroscopy. The results show that doping 2% (mole fraction) metal ions does not change the lattice structure of TiO2 but their absorption peaks can significantly produce red shift in visible light region and the energy band gap decrease, so that M-TiO2 thin films are better than TiO2 thin films for dye-sensitized solar cells anode.The energy band gap of Mg-TiO2 and Ni-TiO2 are 2.19 eV and 2.09 eV respectively, which are close to 1.70 eV of amorphous silicon.

  14. A CdSe thin film: a versatile buffer layer for improving the performance of TiO2 nanorod array:PbS quantum dot solar cells

    Tan, Furui; Wang, Zhijie; Qu, Shengchun; Cao, Dawei; Liu, Kong; Jiang, Qiwei; Yang, Ying; Pang, Shan; Zhang, Weifeng; Lei, Yong; Wang, Zhanguo

    2016-05-01

    To fully utilize the multiple exciton generation effects in quantum dots and improve the overall efficiency of the corresponding photovoltaic devices, nanostructuralizing the electron conducting layer turns out to be a feasible strategy. Herein, PbS quantum dot solar cells were fabricated on the basis of morphologically optimized TiO2 nanorod arrays. By inserting a thin layer of CdSe quantum dots into the interface of TiO2 and PbS, a dramatic enhancement in the power conversion efficiency from 4.2% to 5.2% was realized and the resulting efficiency is one of the highest values for quantum dot solar cells based on nanostructuralized buffer layers. The constructed double heterojunction with a cascade type-II energy level alignment is beneficial for promoting photogenerated charge separation and reducing charge recombination, thereby responsible for the performance improvement, as revealed by steady-state analyses as well as ultra-fast photoluminescence and photovoltage decays. Thus this paper provides a good buffer layer to the community of quantum dot solar cells.To fully utilize the multiple exciton generation effects in quantum dots and improve the overall efficiency of the corresponding photovoltaic devices, nanostructuralizing the electron conducting layer turns out to be a feasible strategy. Herein, PbS quantum dot solar cells were fabricated on the basis of morphologically optimized TiO2 nanorod arrays. By inserting a thin layer of CdSe quantum dots into the interface of TiO2 and PbS, a dramatic enhancement in the power conversion efficiency from 4.2% to 5.2% was realized and the resulting efficiency is one of the highest values for quantum dot solar cells based on nanostructuralized buffer layers. The constructed double heterojunction with a cascade type-II energy level alignment is beneficial for promoting photogenerated charge separation and reducing charge recombination, thereby responsible for the performance improvement, as revealed by steady

  15. Attempts to improve the H2S sensitivity of TiO2 films

    Jagadale, T. C.; Nagmani, Ramgir, N. S.; Prajapat, C. L.; Debnath, A. K.; Aswal, D. K.; Gupta, S. K.

    2016-05-01

    We report the pulsed laser deposited titanium oxide thin film for H2S gas sensing. The surface and bulk electronic structure is revealed using XPS technique. These TiO2 films showed very good selectivity to H2S with response of around ~ 60% at 200°C operating temperature. In order to improve the sensor response so as to realize the technological application, we hereby attempted bi-directional efforts as (i) Nb-doping and (ii) defects engineering in the TiO2 film. It is revealed that Nb-doping reduces response however defect engineering improves the same.

  16. Synthesis of TiO2-loaded Co0.85Se thin films with heterostructure and their enhanced catalytic activity for p-nitrophenol reduction and hydrazine hydrate decomposition

    Zuo, Yong; Song, Ji-Ming; Niu, He-Lin; Mao, Chang-Jie; Zhang, Sheng-Yi; Shen, Yu-Hua

    2016-04-01

    P-nitrophenol (4-NP) and hydrazine hydrate are considered to be highly toxic pollutants in wastewater, and it is of great importance to remove them. Herein, TiO2-loaded Co0.85Se thin films with heterostructure were successfully synthesized by a hydrothermal route. The as-synthesized samples were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, transmission electron microscopy and selective-area electron diffraction. The results demonstrate that TiO2 nanoparticles with a size of about 10 nm are easily loaded on the surface of graphene-like Co0.85Se nanofilms, and the NH3 · H2O plays an important role in the generation and crystallization of TiO2 nanoparticles. Brunauer-Emmett-Teller measurement shows that the obtained nanocomposites have a larger specific surface area (199.3 m2 g-1) than that of Co0.85Se nanofilms (55.17 m2 g-1) and TiO2 nanoparticles (19.49 m2 g-1). The catalytic tests indicate Co0.85Se-TiO2 nanofilms have the highest activity for 4-NP reduction and hydrazine hydrate decomposition within 10 min and 8 min, respectively, compared with the corresponding precursor Co0.85Se nanofilms and TiO2 nanoparticles. The enhanced catalytic performance can be attributed to the larger specific surface area and higher rate of interfacial charge transfer in the heterojunction than that of the single components. In addition, recycling tests show that the as-synthesized sample presents stable conversion efficiency for 4-NP reduction.

  17. Influence of Operating Parameters on Surface Properties of RF Glow Discharge Oxygen Plasma Treated TiO2/PET Film for Biomedical Application

    Thin transparent titania (TiO2) films were coated on the surface of flexible poly (ethylene terephthalate) (PET) surface using standard sol gel techniques. The TiO2/PET thin film surfaces were further modified by exposing the films to a RF glow discharge oxygen plasma. The exposu...

  18. Solar photocatalytic degradation of phenol using pyrolitic TiO2 films deposited inside a tubing

    Solar photocatalytic degradation of phenol was obtained using TiO2 films deposited inside glass tubing. TiO2 thin films inside tubing were obtained by spray-gel technique using a titanium isopropoxide solution conveniently diluted in ethanol. The gas carrier flux, air pressure and temperature were kept during deposition at 5 L/min, 200 kPa, and 200 oC, respectively. Experiments were performed using either the solar radiation or a 300 W lamp simulating the UVA solar radiation component. In order to concentrate the radiation a reflective surface was placed in the back part of the tube. The initial concentration of phenol solution was 20 ppm, and the phenol concentration during the experiment was followed using a standard colorimetric method when aminoantipirine reacts in the sample giving a colored complex. The volume of the phenol solution was limited with a solid aluminum rod placed axially to the glass tube. The obtained TiO2 films were amorphous, but after an annealing at 450oC for 1 h the films crystallize to anatase structure and present photocatalytic activity. The films morphology observed by scanning electron microscopy presented a uniform film and agglomerates of TiO2, the size of the agglomerates increases as Ti isopropoxide/ethanol molar ratio of the starting solution decreases. The precursor concentration solution and film thickness of TiO2 for phenol degradation was optimized. (author)

  19. Wetting and Photocatalytic Properties of TiO2 Nanotube Arrays Prepared via Anodic Oxidation of E-Beam Evaporated Ti Thin Films

    Soon Wook Kim

    2015-01-01

    Full Text Available TiO2 nanotube arrays (TNAs are fabricated on quartz substrate by anodizing E-beam evaporated Ti films. E-beam evaporated Ti films are directly anodized at various anodizing voltages ranging from 20 to 45 V and their morphological, wetting, and photocatalytic properties are examined. The photocatalytic activity of the prepared TNAs is evaluated by the photodecomposition of methylene blue under UV illumination. The TNAs prepared at an anodizing voltage of 30 V have a high roughness of 30.1 nm and a low water contact angle of 7.5°, resulting in a high photocatalytic performance. The surface roughness of the TNAs is found to correlate inversely with the water contact angle. High roughness (i.e., high surface area, which leads to high hydrophilicity, is desirable for effective photocatalytic activity.

  20. Photoelectrochemical characterization and photocatalytic properties of mesoporous TiO 2 / ZrO 2 films

    2006-01-01

    Full Text Available Optically transparent, crack-free mesoporous titania and zirconia-doped titania thin film photocatalysts were fabricated by sol-gel technique, using nonionic amphiphilic block copolymer Pluronic P123 as template. The structural and optical properties of these films were characterized using SEM, low-angle XRD, and UV/Vis spectroscopy, hexane adsorption investigation. Band gap energy and the position of flatband potentials were estimated by photoelectrochemical measurements. Enhancing of photocatalytic activity of zirconia-doped films relative to pure TiO 2 originates from an anodic shift of the valence band edge potential. Catalytic activity of mesoporous TiO 2 and TiO 2 / ZrO 2 ( 5 –50% of ZrO 2 films in the processes of Cr VI to Cr III photoreduction and 2,4-dinitroaniline photooxidation correlates with crystalline size and growth with increasing of specific surface area of the samples.

  1. A CdSe thin film: a versatile buffer layer for improving the performance of TiO2 nanorod array:PbS quantum dot solar cells.

    Tan, Furui; Wang, Zhijie; Qu, Shengchun; Cao, Dawei; Liu, Kong; Jiang, Qiwei; Yang, Ying; Pang, Shan; Zhang, Weifeng; Lei, Yong; Wang, Zhanguo

    2016-05-21

    To fully utilize the multiple exciton generation effects in quantum dots and improve the overall efficiency of the corresponding photovoltaic devices, nanostructuralizing the electron conducting layer turns out to be a feasible strategy. Herein, PbS quantum dot solar cells were fabricated on the basis of morphologically optimized TiO2 nanorod arrays. By inserting a thin layer of CdSe quantum dots into the interface of TiO2 and PbS, a dramatic enhancement in the power conversion efficiency from 4.2% to 5.2% was realized and the resulting efficiency is one of the highest values for quantum dot solar cells based on nanostructuralized buffer layers. The constructed double heterojunction with a cascade type-II energy level alignment is beneficial for promoting photogenerated charge separation and reducing charge recombination, thereby responsible for the performance improvement, as revealed by steady-state analyses as well as ultra-fast photoluminescence and photovoltage decays. Thus this paper provides a good buffer layer to the community of quantum dot solar cells. PMID:27124650

  2. The resistive switching in TiO2 films studied by conductive atomic force microscopy and Kelvin probe force microscopy

    Yuanmin Du; Amit Kumar; Hui Pan; Kaiyang Zeng; Shijie Wang; Ping Yang; Andrew Thye Shen Wee

    2013-01-01

    The resistive switching characteristics of TiO2 thin films were investigated using conductive atomic force microscopy (CAFM) and Kelvin probe force microscopy (KPFM). The as-prepared TiO2 thin films were modulated into higher and lower resistance states by applying a local electric field. We showed that the resistive switching results from charge injection and release assisted by electro-migration of oxygen ions. An integrated model combined with filamentary and interfacial effects was utiliz...

  3. Low-temperature crystallization of TiO2 films by sputter deposition

    Taga, Yasunori; Yamada, Naoomi

    2010-04-01

    Crystalline TiO2 film was formed on PET(polyethlene terephthalate) film by radio frequency sputter deposition method using a sintered TiO2 target by adding H2O gas to Ar gas for sputtering. X-ray diffraction analysis revealed that the crystal structure of the film of 100 nm thick was confirmed to be anatase crystallites of TiO2. In order to elucidate the mechanism of low temperature crystallization thus observed, direct measurement of surface temperature of growing films during sputter deposition was carried out by two methods of an infrared thermometer from the outside of vacuum chamber and a thermocouple attached to the growing film surface. Upon the beginning of sputter deposition in Ar gas, film temperature increased rapidly and became constant at 120°C after 30 min. Addition of H2O gas to Ar gas for sputtering resulted in further increase in film temperature and reached to 230 °C depending on the deposition conditions. Furthermore, photocatalytic performance of decomposition of methylene blue was examined to be enhanced remarkably as a result of crystallization of the film. It was concluded that low temperature crystallization of TiO2 film by sputter deposition was explained in terms of local heating of thin shallow surface region of growing film by kinetic energy deposition of sputtered particles.

  4. Enhanced thermo-mechanical performance and strain-induced band gap reduction of TiO2@PVC nanocomposite films

    Mudassir Hasan; Arghya Narayan Banerjee; Moonyong Lee

    2015-04-01

    The present paper reports the fabrication of TiO2@PVC nanocomposites by incorporating TiO2 in polyvinyl chloride (PVC) followed by solution casting to prepare TiO2@PVC nanocomposite thin films. The asprepared TiO2@PVC nanocomposite films were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, high-resolution transmission electron microscopy, thermogravimetric analysis, optical spectroscopy and mechanical strength analyses. The TiO2@PVC nanocomposites were found to be thermally and mechanically more stable compared with pure PVC. The anatase TiO2 in the TiO2@PVC nanocomposite showed a lower indirect band gap compared with pure TiO2, which can be attributed to the strain within the nanocomposite, thereby affecting the band-structure of the nanocomposite. Significant enhancement in the mechanical properties of TiO2@PVC compared with pure PVC was observed with a 10 wt% TiO2 loading, such as a 50% increase in Young's modulus and almost 100% improvement in the tensile strength.

  5. Fiber texturing in nano-crystalline TiO2 thin films deposited at 150 °C by dc-reactive sputtering on fiber-textured [0 0 0 1] ZnO : Al substrates

    TiO2 thin films were deposited at an effective surface temperature of 150 °C by dc-reactive magnetron sputtering on ZnO : Al oriented substrates having a fiber texture along the [0 0 0 1] axis, and studied by transmission electron microscopy and x-ray diffraction analyses. The substrate texturing was used to tailor the TiO2 structure in such a way that a porous matrix made of anatase nano-grains (10 nm in diameter) is formed instead of an amorphous layer (as observed at 150 °C on glass). Additionally, we demonstrate that, by adding an ex situ 200 °C annealing, the anatase domains also gain a fiber texture with the axes aligned to that of the substrate. The TiO2/AZO structural coupling is expected to play a crucial role for the carrier transport through the interface as required in dye-sensitized solar cells. Moreover, the low temperatures used render the process compatible with commonly used plastics substrates.

  6. Preparation and Analysis of Nano-Crystallite Anatase Phase TiO2 Thin Films%纳米锐钛矿型TiO2薄膜的制备及分析

    辛荣生; 林钰; 蔡彬; 胡斌

    2011-01-01

    采用反应磁控溅射法在玻璃衬底上制备锐钛矿相TiO2薄膜,研究了工艺条件中的氧氩流量比对薄膜润湿角的影响以及溅射气压对薄膜微观结构的影响.对不同氧氩流量比(分别为1/40,1/20,1/10和1/5)时制备的TiO2薄膜进行润湿角测量,润湿角照片显明:氧氩比1/5时薄膜润湿角可减小到8°左右,即提高氧氩比能增强TiO2薄膜的自洁净性能.X射线衍射(XRD)分析表明:当溅射气压降到1.0 Pa时,可以得到锐钛矿型TiO2薄膜晶体,0.5Pa时的XRD图衍射峰更为明显.用分光光度计测量了TiO2薄膜的紫外吸收光谱.由光谱曲线上光吸收阈值与半导体带隙之间的关系计算出了TiO2薄膜的禁带宽度为3.42 eV,表明TiO2薄膜的吸收边出现了一定的蓝移.根据 XRD图谱计算TiO2薄膜的晶粒尺寸,得到的薄膜晶粒尺寸在十几纳米左右,由此说明了TiO2薄膜吸收边发生蓝移的原因;按照锐钛矿相TiO2薄膜XRD图25.3°衍射峰对应的(101)晶面,由Bragg方程计算出其晶面间距为0.3521 nm.表明TiO2薄膜晶体发生了一定的晶格畸变.%The anatase phase TiO2 thin films were prepared on the glass substrates by DC reactive magnetron sputtenng method.The influence of technological condition, such as the O2/Ar flow ratio, on contact angle of the filma and the sputtering pressure on the microstructure of the films, was studied respectively.The contact angle of TiO2 films prepared in different O2/Ar flow ratio ( 1/40 , 1/20,1/10 and 1/5 ) were measured respectively.The contact angle photograph showed that the film contact angle could be reduced to 8° or so when the O2/Ar ratio was 1/5 , this meant that the self-clean property of TiO2 films could be enhanced by increasing O2/Ar ratio.Analysis of X-ray diffraction ( XRD) ahowed that the crystal of anatase phase TiO2 films could be obtained when the sputtering pressure was decreased to 1.0 Pa, the diffraction peak of XRD apectrum was more prominent when the

  7. Low-frequency dielectric properties of intrinsic and Al-doped rutile TiO2 thin films grown by the atomic layer deposition technique

    Kassmi, M.; Pointet, J.; Gonon, P.; Bsiesy, A.; Vallée, C.; Jomni, F.

    2016-06-01

    Dielectric spectroscopy is carried out for intrinsic and aluminum-doped TiO2 rutile films which are deposited on RuO2 by the atomic layer deposition technique. Capacitance and conductance are measured in the 0.1 Hz-100 kHz range, for ac electric fields up to 1 MVrms/cm. Intrinsic films have a much lower dielectric constant than rutile crystals. This is ascribed to the presence of oxygen vacancies which depress polarizability. When Al is substituted for Ti, the dielectric constant further decreases. By considering Al-induced modification of polarizability, a theoretical relationship between the dielectric constant and the Al concentration is proposed. Al doping drastically decreases the loss in the very low frequency part of the spectrum. However, Al doping has almost no effect on the loss at high frequencies. The effect of Al doping on loss is discussed through models of hopping transport implying intrinsic oxygen vacancies and Al related centers. When increasing the ac electric field in the MVrms/cm range, strong voltage non-linearities are evidenced in undoped films. The conductance increases exponentially with the ac field and the capacitance displays negative values (inductive behavior). Hopping barrier lowering is proposed to explain high-field effects. Finally, it is shown that Al doping strongly improves the high-field dielectric behavior.

  8. Crystalline nanoporous metal oxide thin films by post-synthetic hydrothermal transformation: SnO2 and TiO2.

    Shao, Shaofeng; Dimitrov, Momtchil; Guan, Naijia; Köhn, Ralf

    2010-10-01

    Nanostructured and nanoporous metal oxide thin films are rarely accessible by standard synthetic approaches but highly desired for many applications, e.g. as electrodes, transparent conducting coatings, sensors or surface catalysts. Template based sol–gel chemistry combined with post-synthetic hydrothermal treatment allows now the synthesis of nanocrystalline mesostructured porous thin films of metal oxides, e.g. tin oxide and titania. Even in cases where the crystallization cannot be induced highly stable thin films can be achieved, e.g. niobium oxide thin films. We demonstrate how the size of the nanocrystallites influences and stabilizes the mesostructure at temperatures as low as 100 C and thereby in the case of titania or tin dioxide even prevents it from deterioration at higher temperatures up to 400–600 C. PMID:20945539

  9. In situ spectroelectrochemical and theoretical study on the oxidation of a 4H-imidazole-ruthenium dye adsorbed on nanocrystalline TiO2 thin film electrodes.

    Zhang, Ying; Kupfer, Stephan; Zedler, Linda; Schindler, Julian; Bocklitz, Thomas; Guthmuller, Julien; Rau, Sven; Dietzek, Benjamin

    2015-11-28

    Terpyridine 4H-imidazole-ruthenium(II) complexes are considered promising candidates for use as sensitizers in dye sensitized solar cells (DSSCs) by displaying broad absorption in the visible range, where the dominant absorption features are due to metal-to-ligand charge transfer (MLCT) transitions. The ruthenium(III) intermediates resulting from photoinduced MLCT transitions are essential intermediates in the photoredox-cycle of the DSSC. However, their photophysics is much less studied compared to the ruthenium(II) parent systems. To this end, the structural alterations accompanying one-electron oxidation of the RuIm dye series (including a non-carboxylic RuIm precursor, and, carboxylic RuImCOO in solution and anchored to a nanocrystalline TiO2 film) are investigated via in situ experimental and theoretical UV-Vis absorption and resonance Raman (RR) spectroelectrochemistry. The excellent agreement between the experimental and the TDDFT spectra derived in this work allows for an in-depth assignment of UV-Vis and RR spectral features of the dyes. A concordant pronounced wavelength dependence with respect to the charge transfer character has been observed for the model system RuIm, and both RuImCOO in solution and attached on the TiO2 surface. Excitation at long wavelengths leads to the population of ligand-to-metal charge transfer states, i.e. photoreduction of the central ruthenium(III) ion, while high-energy excitation features an intra-ligand charge transfer state localized on the 4H-imidazole moiety. Therefore, these 4H-imidazole ruthenium complexes investigated here are potential multi-photoelectron donors. One electron is donated from MLCT states, and additionally, the 4H-imidazole ligand reveals electron-donating character with a significant contribution to the excited states of the ruthenium(III) complexes upon blue-light irradiation. PMID:26478575

  10. Enhance of electrical properties of resistive switches based on Sr0.1Ba0.9TiO3 and TiO2 thin films by employing a Ni-Cr alloy as contact

    We have investigated the electric-field-induced resistance-switching phenomena of ReRAM cells based on Sr0.1Ba0.9TiO3 and TiO2 thin films fabricated by rf-sputtering technique. Thin films were sandwiched between Pt, Ti and nichrome bottom electrode and Cu top electrode. The I-V measurements at room temperature are non-linear and hysteretic. Cells based on Sr0.1Ba0.9TiO3 present a unipolar resistance-switching phenomenon and it is symmetric with respect to the voltage polarity, while cells based on TiO2 have a bipolar resistance-switching with asymmetric behavior. From the I-V measurements we demonstrated that the nichrome enhances the resistance-switching characteristics of the cells. A reduction of the voltage needed to achieve the HRS-LRS and LRS-HRS transitions are found and a very clear transition between these states is accomplished, in comparison with ReRAM cells fabricated with Pt and Ti electrodes, whose voltage values are large and no clear transitions are presented. This improvement in resistance-switching behavior can be explained due to O2 vacancies formed in the interface because higher affinity for oxygen of nickel and chromium.

  11. Characterisation of samarium and nitrogen co-doped TiO2 films prepared by chemical spray pyrolysis

    Highlights: ► The TiO2:N:Sm thin films deposited by chemical spray pyrolysis have anatase structure. ► According to XPS, N is incorporated into the TiO2 matrix. ► N-doping increases and Sm-doping reduces the crystallite size of the TiO2:N:Sm films. ► Incorporation of N strongly suppresses the Sm3+ PL emission. - Abstract: The sol–gel chemical spray pyrolysis method was used to deposit samarium and nitrogen co-doped TiO2 films onto a quartz substrate at a growth temperature of 450 °C using pulsed spray solution feed, followed by annealing at 500 °C for 2 h in air. The obtained films exhibited anatase structure independent of the doping level. According to XRD analysis, the mean crystallite size of the undoped TiO2, TiO2:N(25) and TiO2:N(5):Sm(5) films was 32, 38 and 20 nm, respectively. According to AFM, the undoped TiO2 film consisted of agglomerates with a size of 30–200 nm. N-doping (25 at%) transformed the agglomerates into individually distinctive grains with a size of ca. 30 nm, while Sm doping (5 at%) caused a significant decrease in the average diameter of the agglomerates to ca. 100 nm. The RMS roughness of the undoped TiO2 film was 1.7 nm; doping resulted in the formation of smoother films with RMS roughness of 0.9–1.4 nm. XPS data indicated that the Sm and N dopants were incorporated into the TiO2 crystal lattice and/or adsorbed on the surface of the film. An increasing nitrogen concentration in the spray solution correlates to a systematic suppressing of the photoluminescence intensity of Sm3+.

  12. Synthesis of amorphous TiO2 modified ZnO nanorod film with enhanced photocatalytic properties

    Highlights: • Synthesis of amorphous TiO2 modified ZnO nanorod films. • A thin layer of amorphous TiO2 was dispersed over the surface of nanorod. • Disordered TiO2 phase improved the optical absorption. • The samples showed enhanced photocatalytic activity. - Abstract: Amorphous TiO2 modified ZnO nanorod films were synthesized via multi-step processes: ZnO nanorod films were prepared by a wet chemical method. Amorphous TiO2 was then anchored on the tops and sides of the nanorods through immersion in tetrabutyltitanate solution for hydrolysis. The as-prepared samples were characterized for the phase structure, chemical state and surface morphology as well as optical absorption using X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and ultraviolet–visible (UV–vis) spectrophotometer. The results showed that the nanorod films were covered by amorphous TiO2 layers, and their visible light absorption ability was strengthened. The photocatalytic studies revealed that TiO2 modified films exhibited enhanced photocatalytic efficiency for decomposition of methyl orange under ultraviolet–visible excitation, which might be attributed to the increased UV–vis light absorption and the separation of the charge carrier and prolonged electron lifetime due to the interface between TiO2 and ZnO

  13. Quantitative Measurements of Photocatalytic CO-Oxidation as a Function of Light Intensity and Wavelength over TiO2 Nanotube Thin Films in mu-Reactors

    Vesborg, Peter Christian Kjærgaard; In, Su-il; Olsen, Jacob L.; Henriksen, Toke Riishøj; Abrams, Billie; Hou, Yidong; Kleiman-Shwarsctein, Alan; Hansen, Ole; Chorkendorff, Ib

    2010-01-01

    Gas-phase photooxidation of CO over TiO2 catalysts (P25 and TiO2 nanotubes) in mu-reactors with quantitative product detection was used to study turnover as a function of illumination intensity over 4 orders of magnitude. Turnover was found to be of order 0.84 in illumination intensity. A CO phot...

  14. Enhanced photocatalysis by coupling of anatase TiO2 film to triangular Ag nanoparticle island.

    Xu, Jinxia; Xiao, Xiangheng; Ren, Feng; Wu, Wei; Dai, Zhigao; Cai, Guangxu; Zhang, Shaofeng; Zhou, Juan; Mei, Fei; Jiang, Changzhong

    2012-01-01

    In order to overcome the low utilization ratio of solar light and high electron-hole pair recombination rate of TiO2, the triangular Ag nanoparticle island is covered on the surface of the TiO2 thin film. Enhancement of the photocatalytic activity of the Ag/TiO2 nanocomposite system is observed. The increase of electron-hole pair generation is caused by the enhanced near-field amplitudes of localized surface plasmon of the Ag nanoparticles. The efficiently suppressed recombination of electron-hole pair caused by the metal-semiconductor contact can also enhance the photocatalytic activity of the TiO2 film. PMID:22548875

  15. Photocatalytic performance of Fe-, Ni-, or Cu-ion implanted TiO2 films under UV light, visible light and sunlight irradiation

    TiO2 thin films were fabricated on microscope glass slides by sol–gel method. Then Fe, Ni or Cu ions were implanted in the films. XRD, XPS and UV–Vis spectrophotometer technologies were used to characterize the films. The results of photodegradation of methyl orange in aqueous solution demonstrate: (1) the films are of visible light response photocatalytic activity; (2) under UV light and sunlight excitation, all the films present less efficient than pure TiO2 film. The photodegradation effects of transition metal ion implanted TiO2 thin films were discussed

  16. Nano-structured TiO2 film fabricated at room temperature and its acoustic properties

    Zhu, Jie; Cao, Wenwu; Jiang, Bei; Zhang, D.S.; Zheng, H.; Zhou, Q.; Shung, K. K.

    2008-01-01

    Nano-structured TiO2 thin film has been successfully fabricated at room temperature. Using a quarter wavelength characterization method, we have measured the acoustic impedance of this porous film, which can be adjusted from 5.3 to 7.19 Mrayl by curing it at different temperatures. The uniform microstructure and easy fabrication at room temperature make this material an excellent candidate for matching layers of ultra-high frequency ultrasonic imaging transducers.

  17. Nano-structured TiO2 film fabricated at room temperature and its acoustic properties

    Nano-structured TiO2 thin film has been successfully fabricated at room temperature. Using a quarter wavelength characterization method, we have measured the acoustic impedance of this porous film, which can be adjusted from 5.3 to 7.19 Mrayl by curing it at different temperatures. The uniform microstructure and easy fabrication at room temperature make this material an excellent candidate for matching layers of ultra-high frequency ultrasonic imaging transducers. (fast track communication)

  18. Surface Texturing of TiO2 Film by Mist Dep osi-tion of TiO2 Nanoparticles

    Gang Qin; Akira Watanabe

    2013-01-01

    Unique and various microstructures of titanium oxide (TiO2) film including macroporous struc-ture, chromatic veins and rings, have been easily fabricated by mist deposition method on silicon substrate with mild preparation conditions. Rutile phase TiO2 nanoparticles were directly used as starting material to prepare film and led to a simple preparation process. It was found that several different microstructures existed in the sample and changed with the varied positions from the center to the edge of the film when the concentration of the TiO2 suspension is 0.06 mol/l, the deposition time is 30 min, the flow rate is 1 l/min and the temperature is 150℃. The surface texturing shows apparent distinction as the concentration of the TiO2 suspension decreased to 0.03 mol/l and 0.01 mol/l.

  19. Effect of annealing treatment on electrical and optical properties of Nb doped TiO2 thin films as a TCO prepared by sol-gel spin coating method

    Fallah, Milad; Zamani-Meymian, Mohammad-Reza; Rahimi, Rahmatollah; Rabbani, Mahboubeh

    2014-10-01

    Anatase niobium doped TiO2 thin films (Ti0.94Nb0.06O2) were prepared on quartz substrates by sol-gel spin coating technique and various initial concentrations ([Ti + Nb] in the solution) of 0.1 M and 0.4 M. All the films dried at 100 °C and then the annealing treatment performed by three different procedures. The influence of different annealing processes and total metal concentrations was studied on crystallinity, transparency, conductivity and morphology of thin films by XRD, EDX, FT-IR and UV-vis transmittance spectroscopy, four point probe, AFM and SEM images. It was found that two-step annealing procedure under vacuum is a more proper way to increase the conductivity of TNO thin films compared to one-step annealing process. Two-step method exhibited the minimum resistivity of 4.4 Ω cm and the transparency of about 50% in the visible region with 36 nm thickness.

  20. Photocatalytic and superhydrophilicity properties of N-doped TiO2 nanothin films

    Pure TiO2 and nitrogen doped titanium dioxide (N-TiO2) thin films were prepared by sol-gel method through spin coating on soda lime glass substrates. TiCl4 and urea were used as Ti and N sources in the sol. XRD results showed nitrogen doping has retarded anatase to rutile phase transformation. The doping also leads to a decrease in roughness of the samples from 4 nm (TiO2) to 1 nm (N-TiO2). However, surface analysis by statistical methods reveals that both surfaces have self-affine structure. Optical band gap of thin films was shifted from 3.65 eV (TiO2) to 3.47 eV (N-TiO2). Hydrophilic conversion and photocatalytic degradation properties of thin films were investigated and exhibited that N-TiO2 thin film has more preferable hydrophilicity and photocatalytic properties under UV illumination.

  1. Preparation of Ce4+, Sb3+-Codoped TiO2 Films in Electric Field Heating-Treatment

    2006-01-01

    Titania is an important catalytic material for photo-catalytic applications, and the sol-gel process is one of the most appropriate technologies to prepare TiO2 thin films. In the present paper, the Ce4+, Sb3+-codoped TiO2 films were prepared by sol-gel method, which were heat-treated with an applied electric filed. The phase transformation behavior of Ce4+, Sb3+-codoped TiO2 film in the electric field heating-treatment was studied by XRD and AFM. It is found that the crystals were homogeneous and the average crystal size was about 60 nm. Studies of photo-catalytic degradation show that the photo-catalytic activity of Ce4+, Sb3+-codoped TiO2 films heated to 500 ℃ in an applied electric field was higher.

  2. Electrochromic Properties of Sol-gel Deposited V2O5 and TiO2-V2O5 Binary Thin Films

    2001-01-01

    Transparent mixed phase (1 - x)V2O5-xTiO2 (x=0,0.1,0.2,0.3,0.4) thin films were prepared on indium tin oxide (ITO) coated glass via sol-gel process. The films were characterized by cyclic voltammetry, optical spectroscopy, scanning electron microscopy, IR and X-ray diffractometer.Electrochemical lithium insertion/extraction showed that the porous structure of sol-gel (1 -x)V2.O5-xTiO2 thin films exhibited good recharge ability of Li+/e- insertion/extraction process.For a 220 nm thick (1 - x)V2O5-xTiO2 film with 90% V2O5, the capacity of charge exchange reached 9 mC/cm2. In both Li+ intercalated and free states, the films were highly transparent to visible light. Such films have potential applications in counter electrodes for electrochromic smart windows and other electrochemical devices.

  3. Photovoltaic performance improvement of dye-sensitized solar cells through introducing In-doped TiO2 film at conducting glass and mesoporous TiO2 interface as an efficient compact layer

    In-doped TiO2 thin film was introduced at the interface of fluorine-doped tin oxide (FTO) substrate and mesoporous TiO2 film by spin-coating method, and its application as a new compact layer material for dye-sensitized solar cells (DSSCs) was investigated. The scanning electron microscopy (SEM), UV-visible spectroscopy, current-voltage characteristics, Mott-Schottky analysis, electrochemical impedance spectroscopy (EIS) analysis and open-circuit voltage decay (OCVD) technique are used to characterize the morphology, optical transmittance and flat-band potentials (Vfb) of In-doped titania compact film and its effect to the photoelectron conversion process. It was found that In-doping increased the transmittance of TiO2 compact layer, the interfacial resistance between FTO substrate and porous TiO2 film and the flat-band potential of TiO2 film. The In-doped TiO2 compact layer effectively suppressed the charge recombination from FTO to the electrolyte, increased the optical absorption of dye and then increased the short-circuit photocurrent density (Jsc). Furthermore, In-doped TiO2 compact layer acted as a weak energy barrier, which increased the electron density in the mesoporous TiO2 film, thus improved open-circuit photovoltage (Voc). As a result, the overall energy conversion efficiency of the DSSC with In-doped TiO2 compact layer was enhanced by 11.9% and 6.9% compared to the DSSC without compact layer and with pure TiO2 compact layer, respectively. It indicated that In-doped TiO2 is a promising compact layer material for dye-sensitized solar cells

  4. Thermal properties of TiO2 films fabricated by atomic layer deposition

    Thin, amorphous, high index, dense, low scattering and absorption (low extinction coefficient) and optical grade TiO2 films of various thicknesses are prepared by Atomic layer deposition (ALD) technique and investigated in terms of thermo-optic coefficient (dn/dT) and temperature dependent density (dρ/dT). The dρ/dT and dρ/dT are calculated by modeling ellipsometric experimental data by developing appropriate optical model such as Cauchy Model. The modeled data was further modeled with Lorentz-Lorenz relation under least-square approach. The dn/dT of TiO2 films shows negative values for thin and positive values for relatively thicker films and reveals no significant changes in dn/dT and dρ/dT when film thickness increases more than ∼ 200 nm. The coefficient values are calculated for a wavelength range of 380–1800 nm. The average values of (dn/dT)60nm= −4.2 ± 0.7 × 10−5°C−1 and (dρ/dT)60nm= −6.6 ± 1.1 × 10−5gcm−3 °C−1 at wavelength of 640 nm. The reported coefficients values are measured and calculated for TiO2 film of thickness t = 60 nm and described in detail

  5. Extraction of optical constants and thickness of nanometre scale TiO2 film

    Yang Ying-Ge; Liu Pi-Jun; Wang Ying; Zhang Ya-Fei

    2005-01-01

    TiO2 thin filmswere deposited on glass substrates by sputtering in a conventional rf magnetron sputtering system. X-ray diffraction pattern and transmission spectrum were measured. The curves of refraction index and extinction coefficient distributions as well as the thickness of films calculated from transmission spectrum were obtained. The optimization problem was also solved using a method based on a constrained nonlinear programming algorithm.

  6. Atomically flat reconstructed rutile TiO2(001) surfaces for oxide film growth

    Wang, Y.; Lee, S.; Vilmercati, P.; Lee, H. N.; Weitering, H. H.; Snijders, P. C.

    2016-02-01

    The availability of low-index rutile TiO2 single crystal substrates with atomically flat surfaces is essential for enabling epitaxial growth of rutile transition metal oxide films. The high surface energy of the rutile (001) surface often leads to surface faceting, which precludes the sputter and annealing treatment commonly used for the preparation of clean and atomically flat TiO2(110) substrate surfaces. In this work, we reveal that stable and atomically flat rutile TiO2(001) surfaces can be prepared with an atomically ordered reconstructed surface already during a furnace annealing treatment in air. We tentatively ascribe this result to the decrease in surface energy associated with the surface reconstruction, which removes the driving force for faceting. Despite the narrow temperature window where this morphology can initially be formed, we demonstrate that it persists in homoepitaxial growth of TiO2(001) thin films. The stabilization of surface reconstructions that prevent faceting of high-surface-energy crystal faces may offer a promising avenue towards the realization of a wider range of high quality epitaxial transition metal oxide heterostructures.

  7. Electrochemical deposition of p-type CuSCN in porous n-type TiO2 films

    We present an energy band model and a method for filling p-type CuSCN in n-type porous TiO2 film. The energy band model is based on the interface energy levels between TiO2/CuSCN heterojunction and the aqueous electrolyte. The whole deposition process is divided into three stages: the uniform nucleation on the internal surface at positive potential, the crystal growth with the cathodic potential shifting negatively and the thermal activated growth at constant potential. This was demonstrated by the electrochemical experiment combining the hydrothermal process. It was found that the obtained TiO2/CuSCN heterojunction exhibited good rectification characteristics, indicating that an intimate electrical contact was formed between the large internal surface of TiO2 film and CuSCN. This novel hydrothermal-electrochemical method may be valuable for fabricating extremely thin absorber (eta)-solar cells and other semiconductor devices

  8. The resistive switching in TiO2 films studied by conductive atomic force microscopy and Kelvin probe force microscopy

    Yuanmin Du

    2013-08-01

    Full Text Available The resistive switching characteristics of TiO2 thin films were investigated using conductive atomic force microscopy (CAFM and Kelvin probe force microscopy (KPFM. The as-prepared TiO2 thin films were modulated into higher and lower resistance states by applying a local electric field. We showed that the resistive switching results from charge injection and release assisted by electro-migration of oxygen ions. An integrated model combined with filamentary and interfacial effects was utilized to elucidate the experimentally observed phenomenon.

  9. Novel Neo-Pentoxide Precursors for MOCVD Thin Films of TiO(2) and ZrO(2).[1

    Boyle, Timothy J.; Francisco, Laila P.; Gallegos, Jesus J.; Rodriguez, Mark A.; Ward, Timothy L.

    1999-07-14

    Two novel Group IV precursors, titanium (IV) neo-pentoxide, [Ti({mu}-ONep)(ONep){sub 3}]{sub 2} (l), and zirconium (IV) neo-pentoxide, [Zr({mu}-ONep)(ONep){sub 3}]{sub 2} (2), were reported to possess relatively high volatility at low temperatures. These compounds were therefore investigated as MOCVD precursors using a lamp-heated cold-wall CVD reactor and direct sublimation without carrier gas. The ONep derivatives proved to be competitive precursors for the production of thin films of the appropriate MO{sub 2} (M = Ti or Zr) materials in comparison to other metallo-organic precursors. Compound 1 was found to sublime at 120 C with a deposition rate of {approximately}0.350 {mu}m/min onto a substrate at 330 C forming the anatase phase with < 1% residual C found in the final film. Compound 2 was found to sublime at 160 C and deposited as crystalline material at 300 C with < 1% residual C found in the final film. A comparison to standard alkoxide and {beta}-diketonates is presented where appropriate.

  10. A study on V+ ion-implanted TiO2 photocatalytic films

    In order to improve photocatalytic property of TiO2 films, the films were implanted with 40 keV V+ ions to doses of 0.6 x l016, l x l016, 3 x l016 or 6 x l016 ions/cm2. Optical band gap of the V+ ion-implanted TiO2 films were measured by a spectrophotometer. The results show that the optical band gap of TiO2 films decreased with the increasing implantion dose. Methyl orange (MO) in aqueous solution was catalyzed by the ion-implanted TiO2 films under visible light. (authors)

  11. Nano-tribological characteristics of TiO2 films on 3-mercaptopropyl trimethoxysilane sulfonated self-assembled monolayer

    J Li; X H Sheng

    2009-10-01

    Silane coupling reagent (3-mercaptopropyl trimethoxysilane (MPTS)) was used to prepare twodimensional self-assembled monolayer (SAM) on silicon substrate. The terminal –SH group was in situ oxidized to –SO3H group to endow the film with good chemisorption ability. Then TiO2 thin films were deposited on the oxidized MPTS–SAM to form composite thin films, making use of the chemisorption ability of the –SO3H group. Atomic force microscope (AFM) and contact angle measurements were used to characterize TiO2 films. Adhesive force and friction force of TiO2 thin films and silicon substrate were measured under various applied normal loads and scanning speed of AFM tip. Results showed that the friction force increased with applied normal loads and scanning speed of AFM tip. In order to study the effect of capillary force, tests were performed in various relative humidities. Results showed that the adhesive force of silicon substrate increases with relative humidities and the adhesive force of TiO2 thin films only increases slightly with relative humidity. Research showed that surfaces with more hydrophobic property revealed the lower adhesive and friction forces.

  12. Optimum Nanoporous TiO2 Film and Its Application to Dye-sensitized Solar Cells

    戴松元; 王孔嘉

    2003-01-01

    Properties of TiO2 nanoporous films, which are one of the crucial technologies in dye-sensitized solar cell, are investigated. The nanocrystalline TiO2 films were prepared with the sol-gel method at different pH in precursor and treatment temperature in autoclave for their application to dye-sensitized solar cells. The thickness of the TiO2 film is very important to the transfer of photoelectron as well as adsorption of dye, it is also known as one of the source to the dark current. The results show that the TiO2 films, such as different particle sizes of TiO2, different pH in precursor and treatment temperature in autoclave, have a strong influence on the photoelectrochemical properties of the dye-sensitized solar cells. We give the optimum TiO2 film thickness and morphology for the application to dye-sensitized solar cells.

  13. Antibacterial effect of silver modified TiO2/PECVD films

    Hájková, P.; Patenka, P. Å.; Krumeich, J.; Exnar, P.; Kolouch, A.; Matoušek, J.; Kočí, P.

    2009-08-01

    This paper deals with photocatalytic activity of silver treated TiO2 films. The TiO2 films were deposited on glass substrates by plasma enhanced chemical vapor deposition (PECVD) in a vacuum reactor with radio frequency (RF) low temperature plasma discharge in the mixture of oxygen and titanium isopropoxide vapors (TTIP). The depositions were performed under different deposition conditions. Subsequently, the surface of TiO2 films was modified by deposition of silver nanoparticles. Photocatalytic activity of both silver modified and unmodified TiO2 films was determined by decomposition of the model organic matter (acid orange 7). Selected TiO2 samples were used for tests of antibacterial activity. These tests were performed on Gram-negative bacteria Escherichia coli. The results clearly proved that presence of silver clusters resulted in enhancement of the photocatalytic activity, which was up to four times higher than that for pure TiO2 films.

  14. Preparation and photoelectrocatalytic activity of Pt(TiO2)-TiO2 hybrid films

    A novel platinised TiO2 film, Pt(TiO2)-TiO2, was prepared by a two-step procedure in which TiO2 as a 'binding layer' was first loaded on ITO (indium-tin oxide) conductive glass plates, and then the platinised TiO2 particles in the suspension was dip-coated on the TiO2 film. The resultant hybrid film was characterized by X-ray reflection diffraction, scanning electron microscope, diffuse reflectance spectra and photoelectrochemical measurement. The experimental results showed that the Pt(TiO2)-TiO2/ITO hybrid film not only was much more stable than the single Pt(TiO2)/ITO film but also possessed rather high photocatalytic and photoelectrocatalytic activities compared with the pure TiO2/ITO film. With respect to formic acid solution, the chemical-oxygen-demand removal efficiency of photoelectrocatalytic oxidation for Pt(TiO2)-TiO2/ITO film is apparently higher than that of photocatalytic and photoelectrocatalytic oxidation of TiO2/ITO film, respectively

  15. Nanocomposite film of TiO2 nanotube and polyoxometalate towards photocatalytic degradation of nitrobenzene

    Highlights: • The film of POMs and TiO2 nanotubes was prepared by electrodeposition. • The photocatalytic activity of the composite film for nitrobenzene was investigated. • The composite film showed higher photocatalytic activity than pure TiO2 nanotubes. • The introduction of POMs into TiO2 could retard electron–hole recombination. - Abstract: The composite film based on polyoxometalates (POMs)-modified TiO2 nanotubes was prepared by electrodeposition method for the photocatalytic degradation of nitrobenzene. The composite film was characterized by field-emission scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy, which indicated that the POMs were well introduced into the TiO2 nanotubes. Furthermore, the photocatalytic properties of the TiO2 nanotubes and POMs-modified TiO2 nanotubes were evaluated by the decomposition of nitrobenzene. POMs-modified TiO2 nanotubes showed much higher photocatalytic activity than pure TiO2 nanotubes. These results provide a promising route to effectively photocatalytic degradation of nitrobenzene by POMs-modified TiO2 nanotubes

  16. Mechanism of photocatalytic bacterial inactivation on TiO2 films involving cell-wall damage and lysis

    C. Pulgarin; Kiwi, J.; Nadtochenko, V.

    2012-01-01

    This article addresses the cell wall damage of Escherichia coil (from now on E. coil) by TiO2 suspensions. The dynamics of TiO2 photocatalysis by thin films layers is described. The films were characterized by FTIR spectroscopy and atomic force microscopy (AFM). The E coil complete inactivation is shown to be due to the partial damage of the cell-wall components (peroxidation). A small increase in the cell wall disorder concomitant with a decrease of the cell wall functional groups leads to h...

  17. Photocatalytic degradation of dimethoate using LbL fabricated TiO2/polymer hybrid films

    Highlights: → The LbL-TiO2 thin films offer many advantages unlike TiO2 used in powder form. → TiO2 can be immobilized using low concentrations on polymer on any substrate using a simple method. → The solution, after the completion of the reaction, can be disposed directly into the environment. → Degradation of organics is complete with no harmful intermediates being produced in the process. → Immobilization is inexpensive and catalysts can be reused making it a cost effective method. - Abstract: Degradation of dimethoate under UV irradiation using TiO2/polymer films prepared by the layer-by-layer (LbL) method was investigated. The thin films were fabricated on glass slides and the surface morphology and roughness of the thin films were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The effect of lamp intensity, catalyst loading in the layers, number of bilayers, pH and initial dimethoate concentration on the degradation of dimethoate was systematically studied. The degradation was monitored using high performance liquid chromatography (HPLC) analysis and total organic carbon (TOC) measurements as a function of irradiation time, to see the change in concentration of dimethoate and mineralization, respectively. Complete degradation of dimethoate was achieved under TiO2 optimum loading of 4 g/L at an UV irradiation time of 180 min. Increase in the lamp intensity, catalyst loading and number of bilayers increased the rate of degradation. At a pH of 4.62, complete degradation of dimethoate was observed. The degradation efficiency decreased with increase in initial dimethoate concentration. The degradation byproducts were analyzed and confirmed by gas chromatography-mass spectra (GC-MS). Toxicity of the irradiated samples was measured using the luminescence of bacteria Vibrio fischeri after 30 min of incubation and the results showed more toxicity than the parent compound. Catalyst reusability

  18. Characteristics and anticorrosion performance of Fe-doped TiO2 films by liquid phase deposition method

    Highlights: • Fe-doped TiO2 films were prepared by liquid phase deposition method. • Higher photoelectrochemical response was observed for the Fe-doped TiO2 film. • The sustained anticorrosion behavior for SUS304 stainless steel was observed. - Abstract: Fe-doped TiO2 thin films were fabricated by liquid phase deposition (LPD) method, using Fe(III) nitrate as both Fe element source and fluoride scavenger instead of commonly-used boric acid (H3BO3). Scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV–vis spectrum were employed to examine the effects of Fe element on morphology, structure and optical characteristics of TiO2 films. The as-prepared films were served as photoanode applied to photogenerated cathodic protection of SUS304 stainless steel (304SS). It was observed that the photoelectrochemical properties of the as-prepared films were enhanced with the addition of Fe element compared to the undoped TiO2 film. The highest photoactivity was achieved for Ti13Fe (Fe/Ti = 3 molar ratio) film prepared in precursor bath containing 0.02 M TiF4 + 0.06 M Fe(NO3)3 under white-light illumination. The effective anticorrosion behaviors can be attributed to the Fe element incorporation which decreases the probability of photogenerated charge-carrier recombination and extends the light response range of Fe-doped TiO2 films appeared to visible-light region

  19. Surface properties and biocompatibility of nanostructured TiO2 film deposited by RF magnetron sputtering.

    Majeed, Asif; He, Jie; Jiao, Lingrui; Zhong, Xiaoxia; Sheng, Zhengming

    2015-01-01

    Nanostructured TiO2 films are deposited on a silicon substrate using 150-W power from the RF magnetron sputtering at working pressures of 3 to 5 Pa, with no substrate bias, and at 3 Pa with a substrate bias of -50 V. X-ray diffraction (XRD) analysis reveals that TiO2 films deposited on unbiased as well as biased substrates are all amorphous. Surface properties such as surface roughness and wettability of TiO2 films, grown in a plasma environment, under biased and unbiased substrate conditions are reported according to the said parameters of RF power and the working pressures. Primary rat osteoblasts (MC3T3-E1) cells have been cultured on nanostructured TiO2 films fabricated at different conditions of substrate bias and working pressures. The effects of roughness and hydrophilicity of nanostructured TiO2 films on cell density and cell spreading have been discussed. PMID:25852353

  20. Formation of TiO2 Modified Film on Carbon Steel

    Laizhou SONG; Shizhe SONG; Zhiming GAO

    2004-01-01

    A new technique for preparing TiO2 modified film on carbon steel was accomplished by electroless plating and sol-gel composite process. The artificial neural network was applied to optimize the preparing condition of TiO2 modified film. The optimized condition for forming TiO2 modified film on carbon steel was that NiP plating for 50 min,dip-coating times as 4, heat treatment time for 2 h, and the molar ratio of complexing agent and Ti(OC4HZ9)4 kept 1.5:1. The results showed that TiO2 modified film have good corrosion resistance. The result conformed that it is feasible to design the preparing conditions of TiO2 modified film by artificial neural network.

  1. Hydrophilic property of SiO2-TiO2 overlayer films and TiO2/SiO2 mixing films

    关凯书; 徐宏; 吕宝君

    2004-01-01

    The photo-induced hydrophilicity of SiO2 overlayer on TiO2 films prepared by sol-gel method was investigated by means of soak angle measurement, XPS, UV-VIS and FTIR spectra. The results show that, compared with the TiO2 film without SiO2 overlayer, when the TiO2 film is thoroughly covered by SiO2 overlayer, the hydrophilicity and the sustained effect are enhanced. It is found that the significant growth of the OH group occurs in the surface of SiO2 overlayer. The different mechanism of enhanced hydrophilicity between SiO2 overlayer on TiO2 films and TiO2/SiO2 mixing films was analyzed. The result suggests that the photo-generated electrons created in the interface between TiO2 and SiO2 tend to reduce the Ti(Ⅳ) cation to the Ti(Ⅲ) state, and the photogenerated holes transmit through the SiO2 layer to uppermost surface efficiently. Once the holes go up to the surface, they tend to make the surface hydrophilic. The stable hydrophilicity of SiO2 overlayer which adsorbs more stable OH groups, enhances the sustained effect, i.e. the super-hydrophilic state can be maintained for a long time in dark place.

  2. Photocatalytic degradation kinetics of Rhodamine B cata-lyzed by nanosized TiO2 film

    2003-01-01

    A fixed bed photocatalytic reactor was designed, and dynamic fast scan of UV-Vis adsorption spectrum was adopted to study the photocatalytic degradation dynamic behavior of Rhodamine B, a kind of dye generally recognized as to be degraded difficultly, on the surface of nanosized TiO2 thin film. The results indicate that the photocatalytic degradation process of Rhodamine B does not comply with the first-order reaction kinetic process. As a result, a kinetic model of Rhodamine B photocatalytic degradation reaction is brought forward, and the model is proved by the theoretical deduction and experiment.

  3. Electrochromism in sol-gel deposited TiO2 films

    Bell, John M.; Barczynska, Joanna; Evans, L. A.; MacDonald, Kathleen A.; Wang, J.; Green, David C.; Smith, Geoffrey B.

    1994-09-01

    Electrochromism is sol-gel deposited TiO2 films and films containing TiO2 and WO3 has been observed. The films are deposited by dip-coating from a precursor containing titanium isopropoxide in ethanol or titanium propoxide in ethanol, and after deposition the films are heat treated to between 250 degree(s)C and 300 degree(s)C. The films do not show any signs of crystallinity. However substantial coloration is observed using Li+ ions in a non-aqueous electrolyte, both in pure TiO2 films and in mixed metal oxide films (WO3:TiO2), although the voltage required to produce coloration is different in the two cases. Results will be presented detailing the optical switching and charge transport properties of the films during cyclic voltammetry. These results will be used to compare the performance of the TiO2 films with other electrochromics. The TiO2 and mixed metal films all color cathodically, and the colored state is a neutral greyish color for TiO2, while the bleached state is transparent and colorless, Results on coloration efficiency and the stability under repeated electrochemical cycling will also be presented. The neutral color of the TiO2 films and mixed-metal films means that electrochromic windows based on TiO2 may have significant advantages over WO3-based windows. A detailed analysis of the optical properties of the colored state of the films will be presented. The dynamics of coloration for these films is also under investigation, and preliminary results will be presented.

  4. Nano-crystalline thin and nano-particulate thick TiO2 layer: Cost effective sequential deposition and study on dye sensitized solar cell characteristics

    Highlights: • Thin TiO2 layer is deposited on conducting substrate using sol–gel based dip coating. • TiO2 nano-particles are synthesized using hydrothermal route. • Thick TiO2 particulate layer is deposited on prepared thin layer. • Dye sensitized solar cells are made using thin and thick layer based photo-anode. • Introduction of thin layer in particulate photo-anode improves the cell efficiency. - Abstract: A compact thin TiO2 passivation layer is introduced between the mesoporous TiO2 nano-particulate layer and the conducting glass substrate to prepare photo-anode for dye-sensitized solar cell (DSSC). In order to understand the effect of passivation layer, other two DSSCs are also developed separately using TiO2 nano-particulate and compact thin film based photo-anodes. Nano-particles are prepared using hydrothermal synthesis route and the compact passivation layer is prepared by simply dip coating the precursor sol prepared through wet chemical route. The TiO2 compact layer and the nano-particles are characterised in terms of their micro-structural features and phase formation behavior. It is found that introduction of a compact TiO2 layer in between the mesoporous TiO2 nano-particulate layer and the conducting substrate improves the solar to electric conversion efficiency of the fabricated cell. The dense thin passivation layer is supposed to enhance the photo-excited electron transfer and prevent the recombination of photo-excited electrons

  5. Formation Mechanistism Study of TiO2 Film Comprising Nanotubes and Nanoparticles

    Di Yang; Yi-quan Wang; Guo-bin Ren; Shuai Feng; Yuan-yuan Chen; Wen-zhong Wang

    2012-01-01

    A novel titanium dioxide (TiO2) film comprising both nanotubes and nanopaticles was fabricated by an anodization process of the modified titanium.The local electric field at the anodized surface was simulated and its influence on the morphology of the TiO2 film was discussed.The results show that the electric field strength is enhanced by the covering.The growth rate of TiO2 increases with the assist of the local electric field.However,TiO2 dissolution is hindered since the local electric field prevents [TiF6]6- from diffusing.It means that the balance condition for the formation of nanotubes is broken,and TiO2 nanoparticles are formed.Moreover,the crystal structure of the TiO2 film was confirmed using X-ray diffraction and Raman analysis.The anatase is a main phase for the proposed film.

  6. Liquid phase deposition of WO3/TiO2 heterojunction films with high photoelectrocatalytic activity under visible light irradiation

    Highlights: • Liquid phase deposition is developed for preparing WO3/TiO2 heterojunction films. • TiO2 film provides an excellent platform for WO3 deposition. • WO3 expands the absorption band edge of TiO2 film to visible light region. • WO3/TiO2 heterojunction film shows high photoelectrocatalytic activity. - ABSTRACT: The heterojunction films of WO3/TiO2 were prepared by liquid phase deposition (LPD) method via two-step processes. The scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopic analysis indicated that flower-like WO3 film was successfully deposited on TiO2 film with the LPD processes. The TiO2 film provided an excellent platform for WO3 deposition while WO3 obviously expanded the absorption of TiO2 film to visible light. As the result, the heterojunction film of WO3/TiO2 exhibited higher photocurrent response to visible light illumination than pure TiO2 or WO3 film. The photoelectrocatalytic (PEC) activity of WO3/TiO2 film was evaluated by degrading Rhodamin B (RhB) and 4-chlorophenol (4-CP) under visible light irradiation. The results showed that the LPD WO3/TiO2 film possessed high PEC activity for efficient removal of various refractory organic pollutants

  7. Photocatalytic activity of porous TiO2 films prepared by anodic oxidation

    WANG Wei; TAO Jie; WANG Tao; WANG Ling

    2007-01-01

    Anatase titanium dioxide is an active photocatalyst, however, it is difficult to be immobilized on the substrate.The crystalline TiO2 porous film was prepared directly on the surface of pure titanium by anodic oxidation. The film was then used for photocatalysis via the methyl orange degradation method. The effects of anodization voltage, pH value, TiO2 film area and degradation time on the photocatalyst were investigated respectively by UV-visible spectrum. It was indicated that the TiO2 film prepared by anodic oxidation at 140 V had the best photocatalysis capability and the degradation of methyl orange was accelerated with acid addition.

  8. Preparation of photo-catalysis TiO2 films by combined plasma surface treatment

    TiO2 films with excellent bonding strength were fabricated on stainless steel substrate by plasma surface alloying and thermal oxidation duplex processing. Controllable elemental distribution and structure of the films could be achieved at 400-600 degree C. The films were characterized by metallography, glow discharge spectrometer (GDOES) and X-ray diffraction. The results show that the TiO2 films are of dense and uniform anatase. The Ti and O contents of the films are in gradient distribution. Phenol-containing wastewater was used to test photo-catalytic performance of the films. The TiO2 films have a degradation rate of phenol of about 73.5% in 3 h, much higher than commercial products of TiO2 powders. (authors)

  9. Well-organized meso-macroporous TiO2/SiO2 film derived from amphiphilic rubbery comb copolymer.

    Jeon, Harim; Lee, Chang Soo; Patel, Rajkumar; Kim, Jong Hak

    2015-04-15

    We report the facile synthesis of a well-organized meso-macroporous TiO2/SiO2 thin film with high porosity and good interconnectivity from a binary mixture (i.e., titania precursor and polymer template). Our process is based on self-assembly of the amphiphilic rubbery comb copolymer, poly(dimethylsiloxane)-g-poly(oxyethylene methacrylate) (PDMS-g-POEM) with titanium tetraisopropoxide (TTIP). SiO2 is self-provided by thermal oxidation of PDMS chains during calcination under air. The selective, preferential interaction between TTIP and the hydrophilic POEM chains was responsible for the formation of well-organized TiO2/SiO2 films, as supported by transmission electron microscopy, scanning electron microscopy, X-ray photospectroscopy, and X-ray diffraction analyses. We investigated in detail the effect of precursor content, solvent type, and polymer concentration on thin film morphology. Photodegradation of methyl orange by the well-organized meso-macroporous TiO2/SiO2 film was greater than that of a dense TiO2 film prepared without PDMS-g-POEM as well as a SiO2-etched TiO2 film. These results indicate that the well-organized structure and SiO2 doping of the TiO2 film play a pivotal role in enhancing its photocatalytic properties. PMID:25805232

  10. Antibacterial activity of DLC films containing TiO2 nanoparticles.

    Marciano, F R; Lima-Oliveira, D A; Da-Silva, N S; Diniz, A V; Corat, E J; Trava-Airoldi, V J

    2009-12-01

    Diamond-like carbon (DLC) films have been the focus of extensive research in recent years due to their potential applications as surface coatings on biomedical devices. Titanium dioxide (TiO2) in the anatase crystalline form is a strong bactericidal agent when exposed to near-UV light. In this work we investigate the bactericidal activity of DLC films containing TiO2 nanoparticles. The films were grown on 316L stainless-steel substrates from a dispersion of TiO2 in hexane using plasma-enhanced chemical vapor deposition. The composition, bonding structure, surface energy, stress, and surface roughness of these films were also evaluated. The antibacterial tests were performed against Escherichia coli (E. coli) and the results were compared to the bacterial adhesion force to the studied surfaces. The presence of TiO2 in DLC bulk was confirmed by Raman spectroscopy. As TiO2 content increased, I(D)/I(G) ratio, hydrogen content, and roughness also increased; the films became more hydrophilic, with higher surface free energy and the interfacial energy of bacteria adhesion decreased. Experimental results show that TiO2 increased DLC bactericidal activity. Pure DLC films were thermodynamically unfavorable to bacterial adhesion. However, the chemical interaction between the E. coli and the studied films increased for the films with higher TiO2 concentration. As TiO2 bactericidal activity starts its action by oxidative damage to the bacteria wall, a decrease in the interfacial energy of bacteria adhesion causes an increase in the chemical interaction between E. coli and the films, which is an additional factor for the increasing bactericidal activity. From these results, DLC with TiO2 nanoparticles can be useful for producing coatings with antibacterial properties. PMID:19758597

  11. Antimicrobial Activity of TiO2 Nanoparticle-Coated Film for Potential Food Packaging Applications

    Siti Hajar Othman

    2014-01-01

    Full Text Available Recent uses of titanium dioxide (TiO2 have involved various applications which include the food industry. This study aims to develop TiO2 nanoparticle-coated film for potential food packaging applications due to the photocatalytic antimicrobial property of TiO2. The TiO2 nanoparticles with varying concentrations (0–0.11 g/ 100 mL organic solvent were coated on food packaging film, particularly low density polyethylene (LDPE film. The antimicrobial activity of the films was investigated by their capability to inactivate Escherichia coli (E. coli in an actual food packaging application test under various conditions, including types of light (fluorescent and ultraviolet (UV and the length of time the film was exposed to light (one–three days. The antimicrobial activity of the TiO2 nanoparticle-coated films exposed under both types of lighting was found to increase with an increase in the TiO2 nanoparticle concentration and the light exposure time. It was also found that the antimicrobial activity of the films exposed under UV light was higher than that under fluorescent light. The developed film has the potential to be used as a food packaging film that can extend the shelf life, maintain the quality, and assure the safety of food.

  12. Photoelectrochemical activity of liquid phase deposited TiO2 film for degradation of benzotriazole

    TiO2 film deposited on glassy carbon electrode surface was prepared via the liquid phase deposition (LPD). The deposited TiO2 film before and after calcination was characterized with scanning electron microscopy (SEM) and X-ray diffraction (XRD). Based on the high photoelectrochemical activity of calcined LPD TiO2 film, the photoelectrocatalytic degradation of benzotriazole (BTA) was investigated. Compared with the electrochemical oxidation process, direct photolysis or photocatalysis for treatment of BTA, a synergetic photoelectrocatalytic degradation effect was observed using the LPD TiO2 film-coated electrode. Various factors influencing the photoelectrocatalytic degradation of BTA such as film calcination, applied bias potential, pH value, supporting electrolyte concentration and initial concentration of BTA were investigated. The COD removal for BTA solution was analyzed to evaluate the mineralization of the PEC process. Based on the degradation experimental results, a possible photoelectrocatalytic degradation mechanism for BTA was proposed.

  13. Photocatalytic Water Treatment on TiO2 Thin Layers.

    Šolcová, Olga; Spáčilová, L.; Maléterová, Ywetta; Morozová, Magdalena; Ezechiáš, Martin; Křesinová, Zdena

    2016-01-01

    Roč. 57, č. 25 (2016), s. 11631-11638. ISSN 1944-3994. [International Conference on Protection and Restoration of the Environment /12./. Skiathos Island, 29.06.2014-03.07.2014] R&D Projects: GA TA ČR TA01020804 Institutional support: RVO:67985858 ; RVO:61388971 Keywords : water purification * endocrine disruptor * photocatalytic * TiO2 layers Subject RIV: CI - Industrial Chemistry, Chemical Engineering; EE - Microbiology, Virology (MBU-M) Impact factor: 1.173, year: 2014

  14. Polycrystalline TiO2 Thin Films Deposited by a Modified Oxygen Pulse Magnetron Sputtering%氧脉冲磁控溅射法制备多晶TiO2薄膜

    王秩伟; 龚恒翔; 李雪; 谌家军

    2008-01-01

    Polycrystalline TiO2 thin films were deposited on slide glass by a modified sputtering,which called oxygen pulse DC magnetron reactive sputtering as oxygen was systematically controlled like pulse.This technology can effectively abate target poisoning and increase the deposition rate by about 7 times compared with conventional reactive sputtering.The effects of deposition time,oxygen partial pressure and time of oxygen on-off on deposition rate,crystal structure and surface topography were investigated by elliptical polarization measurement,X-ray diffraction(XRD),and field emission scanning electron microscopy(FE-SEM),respectively.The results indicated that samples deposited at oxygen partial pressure of 30%,Toff=30s and 20s have the best crystalline structure with unique phase of rutile or anatase and at TooFF=30s TiO2 film has the best surface topography.Besides,the sample tends to form rutile under higher deposition rate and lower oxygen concentration.Electrical resistivity Was studied by Van der Pauw method and samples with which around 10 cm deposited at oxygen partial pressure of 30%,ToFF=30s and 50%,ToFF=40s,respectively,are suit for our further study.%利用一种改进的溅射方法在载波片上制备了多晶TiO2薄膜.由于该法在溅射过程中氧气控制得像脉冲一样,所以称之为氧脉冲直流磁控反应溅射.它能有效的减轻靶中毒,样品沉积速率达到传统反应溅射法的7倍左右.分别利用椭圆偏振测厚仪、X射线衍射仪和场发射扫描电子显微镜研究了沉积时间、氧分压以及氧气开关时间对沉积速率、晶体结构和表面形貌的影响.研究结果显示,在氧分压为30%,断氧时间Toff=30s和20s下制备的样品具有最好的金红石相或锐钛矿相单一晶体结构,并且在Toff=30s时,具有最佳的表面形貌.此外.在较高沉积速率和较低氧分压下,样品更趋向于生成金红石相.利用范德堡法研究了样品的电阻率,在氧分压为30%,Toff

  15. TiO2-BASED Composite Films for the Photodegradation of Oxytetracycline

    Li, Hui; Guan, Ling-Xiao; Feng, Ji-Jun; Li, Fang; Yao, Ming-Ming

    2015-02-01

    The spread of the antibiotic oxytetracycline (OTC) has been thought as a threat to the safety of drinking water. In this paper, the photocatalytic activity of the nanocrystalline Fe/Ca co-doped TiO2-SiO2 composite film for the degradation of OTC was studied. The films were characterized by field emission scanning electron microscopy (FE-SEM) equipped with energy-dispersive spectroscopy (EDS), N2 adsorption/desorption isotherms, photoluminescence (PL) spectra, and UV-Vis diffraction reflectance absorption spectra (DRS). The FE-SEM results indicated that the Fe/Ca co-doped TiO2-SiO2 film was composed of smaller nanoparticles compared to pure TiO2 or TiO2-SiO2 film. The BET surface area results showed that the specific surface area of the pure TiO2, TiO2-SiO2 and Ca2+/Fe3+ co-doped TiO2-SiO2 is 118.3 m2g-1, 294.3 m2g-1 and 393.7 m2g-1, respectively. The DRS and PL spectra revealed that the Fe/Ca co-doped TiO2-SiO2 film had strong visible light adsorption and diminished electrons/holes recombination. Experimental results showed that the Fe/Ca co-doped TiO2-SiO2 film is effective in the degradation of OTC under both UV and visible light irradiation.

  16. Influence of Acetylacetone on Photocatalytic Properties of TiO2 Thin Films Deposited on PMMA Substrates%乙酰丙酮对PMMA负载锐钛矿型TiO2薄膜及其光催化性能影响

    张志清; 黄剑锋; 曹丽云; 吴建鹏

    2011-01-01

    The nanociystalline TiO2 solution was prepared using a microwave hydrotheimal process to treat precursor liquid which was obtained by control the hydrolysis of titanium-n-butoxide in the presence of excessive water and acetylacetone (AcAcH). Then nanociystalline TiO2 thin films were deposited on polymethylmethacrylate (PMMA) substrates by dip-coating process from TiO2 colloidal solution. The phase composition of TiO2 nanoparticles, morphologies and optical properties of TiO2 thin films deposited on PMMA substrates were characterized by X-ray diffraction (XRD), fourier transform infrared spectrometer (FTTR), transmission electron microscope (TEM), atomic force microscopy (AFM) and UV-vis spectroscopy. Meanwhile photocatalytic properties of TiO2 films were investigated by degradation of Rhodamine B ( RhB) under ultraviolet radiation. Trie results indicate that anatase TiO2 colloidal solution modified by AcAcH is disperse, uniform, deposit-free and the deposited TiO2 thin films are transparent, homogeneous and compact, and show high efficiency of photocatalysis. Rhodamine B has been degradated over 90% at 180 min%以钛酸丁酯作为钛源,水为溶剂,乙酰丙酮(AcAcH)为表面修饰剂,采用微波水热辅助溶胶-凝胶法制备了纳米晶二氧化钛水溶液,利用提拉镀膜法在聚合物聚甲基丙烯酸甲酯(PMMA)基板上沉积得到了透明TiO2纳米晶薄膜.通过X射线衍射(XRD)、红外光谱(FTIR)、透射电子显微镜(TEM)、原子力显微镜(AFM)和紫外-可见光吸收光谱(UV-Vis)等对TiO2纳米颗粒和薄膜的晶相组成、表面形貌及光学性能进行表征.同时通过紫外光光催化降解罗丹明B研究了TiO2薄膜的光催化性能.结果表明:通过引入乙酰丙酮,可以得到高度分散、晶相为锐钛矿型的TiO2水溶胶,在PMMA基板上沉积得到的薄膜表面平整、致密,具有良好的透光率,经过180 min紫外光照射,对罗丹明B的降解率达到90%以上.

  17. Use of co-spray pyrolysis for synthesizing nitrogen-doped TiO2 films

    Nho Pham Van; Pham Hoang Ngan

    2013-10-01

    Nitrogen-doped nanocrystalline TiO2 is well known as the most promising photocatalyst. Despite many years after discovery, seeking of efficient method to prepare TiO2 doped with nitrogen still attracts a lot of attention. In this paper, we present the result of using co-spray pyrolysis to synthesize nitrogen-doped TiO2 films from TiCl4 and NH4NO3. The grown films were subjected to XRD, SEM, photocatalysis, absorption spectra and visible-light photovoltaic investigations. All the deposited films were of nanosized polycrystal, high crystallinity, pure anatase and porosity. Specific characteristics involved nitrogen doping such as enhanced photocatalytic activity, bandgap narrowing, visible light responsibility and typical correlation of the photoactivity with nitrogen concentration were all exhibited. Obtained results proved that high photoactive nitrogen-doped TiO2 films can be synthesized by co-spray pyrolysis.

  18. SAXS Studies of TiO2 Nanoparticles in Polymer Electrolytes and in Nanostructured Films

    Sigrid Bernstorff

    2010-11-01

    Full Text Available Polymer electrolytes as nanostructured materials are very attractive components for batteries and opto-electronic devices. (PEO8ZnCl2 polymer electrolytes were prepared from PEO and ZnCl2. The nanocomposites (PEO8ZnCl2/TiO2 themselves contained TiO2 nanograins. In this work, the influence of the TiO2 nanograins on the morphology and ionic conductivity of the nanocomposite was systematically studied by transmission small-angle X-ray scattering (SAXS simultaneously recorded with wide-angle X-ray diffraction (WAXD and differential scanning calorimetry (DSC at the synchrotron ELETTRA. Films containing nanosized grains of titanium dioxide (TiO2 are widely used in the research of optical and photovoltaic devices. The TiO2 films, prepared by chemical vapor deposition and e-beam epitaxy, were annealed in hydrogen atmospheres in the temperature range between 20 °C and 900 °C in order to study anatase-rutile phase transition at 740 °C. Also, grazing-incidence small angle X-ray scattering (GISAXS spectra for each TiO2 film were measured in reflection geometry at different grazing incident angles. Environmentally friendly galvanic cells, as well as solar cells of the second generation, are to be constructed with TiO2 film as working electrode, and nanocomposite polymer as electrolyte.

  19. Blister formation in rutile TiO2(1 0 0) films by helium irradiation

    Incident energy, fluence of helium ion and temperature for blister formation in rutile TiO2(1 0 0) films were investigated. Epitaxial rutile TiO2(1 0 0) films were grown on α-Al2O3(0 0 0 1) substrates by pulsed laser deposition. The films were irradiated at room temperature and 95 K with 4 keV helium ions up to fluence range from 1.0 x 1016 to 2.3 x 1017 ions/cm2. The surface morphology of TiO2 films was observed by scanning electron microscope and atomic force microscope. Rutherford backscattering spectroscopy with channeling was used to determine the depth profile of radiation-induced damage. In the case of room temperature irradiation with fluences higher than 2 x 1016 ions/cm2, helium blisters with 100-200 nm sizes in TiO2 films were observed. Furthermore, helium irradiation at 95 K resulted in smaller size blisters (∼50 nm). It is suggested that the size of blisters in TiO2(1 0 0) films is strongly affected by the temperature during the helium irradiation. The photo-induced superhydrophilicity of TiO2 films was improved by high fluence helium irradiation, which caused blister growth

  20. Nucleation dynamics of nanostructural TiO2 films with controllable phases on (001) LaAlO3

    Microstructure evolution and nucleation dynamics of TiO2 nanostructural thin films on (001) LaAlO3 substrates grown by the polymer-assisted deposition technique have been systematically studied with the increase of annealing temperature. Epitaxial anatase TiO2 phase with nanometer-scaled periodic surface strip patterns can be achieved when the sample is annealed at 900 ° C. It is also found that the morphology of the surface pattern is related to the ramping rate of the temperature during annealing. The formation of the surface strip pattern can be considered to be associated with the diffusion limit growth dynamics. The surface pattern structure was found to strongly affect the hydrophilic properties of the thin films. (paper)

  1. Characterization of nano porous TiO2 films prepared by sol-gel method

    Nano-porous TiO2 films as a key component in dye sensitized and extremely thin absorber (ETA) solar cells were prepared by the sol-gel method using spin-coating and spray pyrolysis deposition techniques. The precursor sol contained titanium (IV) iso-prop-oxide, acetylacetone and polyethylene glycol (PEG) in ethanol. Glass and n-type Si (100) were used as substrates. SEM, XRD and FT-IR were used to study the effect of the PEG concentration in the precursor solution as well as different annealing routes on the film composition and structural properties. Crystalline films with anatase structure could be grown by the spray technique at 500 C. Post-annealing at 500 C increases the crystallite size (from 5 to 9 nm) and results in an average pore size around 40 nm. A film thickness of about 2.3 μm is attained using 50 spray pulses. In spin coated films the formation of Ti-O-Ti anatase bonds is observed after annealing at 450 C. Crystalline films can be prepared by annealing at temperatures above 700 C. Surface morphology and pore size of spin coated films are controlled by the amount of PEG in the sol. The film thickness is around 120 nm after three coating cycles. (authors)

  2. Nanoindentation investigation of mechanical properties of ZrO2, ZrO2–Y2O3, Al2O3 and TiO2 thin films deposited on stainless steel OC 404 substrate by spray pyrolysis

    Highlights: • ZrO2, ZrO2–Y2O3, Al2O3 and TiO2 films were deposited by spray pyrolysis. • Surface morphology and structure of the films were characterized via SEM and X-ray. • Mechanical properties of films were investigated by nanoindentation and was established that their values exceed these for pure metals. - Abstract: Thin ZrO2, ZrO2–Y2O3, Al2O3 and TiO2 films were deposited by spray pyrolysis method on stainless steel OC 404 substrate with thickness 50 μm. The thicknesses of obtained films varied from 0.50 to 0.64 μm. The surface morphology and structure of the films were characterized by scanning electron microscopy in secondary electron imaging mode. The X-ray diffraction measurements for determination of the lattice parameters, the average crystallite size and the sample strain were performed. Mechanical properties of investigated films and substrate were investigated by nanoindentation experiments, using Nano Indenter G200 (Agilent Technologies). As a result of nanoindentation experiments, load–displacement curves were obtained and two mechanical characteristics of the substrate and investigated films – indentation hardness (HIT) and indentation modulus (EIT) – were calculated using Oliver and Pharr approximation method. Dependence of indentation modulus and indentation hardness on depth of indentation was investigated as well

  3. Photo-oxidative degradation of TiO2/polypropylene films

    Graphical abstract: - Highlights: • Photo-oxidative degradation of polypropylene is accelerated by TiO2 incorporation. • Weight loss, FTIR, SEM and GPC shown high degree of degradation of polypropylene. • A mechanism of the photo-degradation of polypropylene by TiO2 is proposed. - Abstract: Photo-oxidative degradation of polypropylene films with TiO2 nanoparticles incorporated was studied in a chamber of weathering with Xenon lamps as irradiation source. TiO2 powder with crystalline structure of anatase was synthesized by thermal treatments at 400 and 500 °C starting from a precursor material obtained by sol–gel method. Composites of TiO2/polypropylene were prepared with 0.1, 0.5 and 1.0 wt% of TiO2. The mixture of components was performed using a twin screw extruder, the resulting material was pelletized by mechanical fragmenting and then hot-pressed in order to form polypropylene films with TiO2 dispersed homogeneously. Photo-oxidative degradation process was followed by visual inspection, weight loss of films, scanning electron microscopy (SEM), infrared spectroscopy with Fourier transformed (FTIR), and gel permeation chromatography (GPC)

  4. Polymer Photovoltaic Cell Using TiO2/G-PEDOT Nanocomplex Film as Electrode

    F. X. Xie

    2008-01-01

    Full Text Available Using TiO2/G-PEDOT (PEDOT/PSS doped with glycerol nanocomplex film as a substitute for metal electrode in organic photovoltaic cell is described. Indium tin oxide (ITO worked as cathode and TiO2/G-PEDOT nanocomplex works as anode. The thickness of TiO2 layer in nanocomplex greatly affects the act of this nonmetallic electrode of the device. To enhance its performance, this inverted organic photovoltaic cell uses another TiO2 layer as electron selective layer contacted to ITO coated glass substrates. All films made by solution processing techniques are coated on the transparent substrate (glass with a conducting film ITO. The efficiency of this solar cell is compared with the conventional device using Al as electrode.

  5. Evolution of different structural phases of TiO2 films with oxygen partial pressure and Fe doping and their electrical properties

    Highlights: ► Fe doped and undoped TiO2 films are grown with varying oxygen partial pressure (OPP). ► Different structural and electrical phases of TiO2 films evolve with OPP. ► Phases obtained at different OPP are not same for films with different Fe doping. ► XPS confirms Fe is not in metal cluster form. ► Charge ordering is observed in magneli phase of Fe doped and undoped TiO2 films. -- Abstract: We have studied the influence of oxygen partial pressure (OPP; 250 mTorr–1 × 10−5 Torr) and Fe doping (2 and 4 at.%) on structural and electrical properties of TiO2 thin films on LaAlO3 substrates. X-ray photoelectron spectroscopy suggests that Fe is not in metal cluster form. It is found that the evolution of the three phases; anatase, rutile and brookite of TiO2 as well as the magneli phase (TinO2n−1) strongly depends on the OPP and Fe doping concentration. All the films grown at 250 mTorr show insulating behavior, whereas films grown at 1 × 10−2 and 1 × 10−4 Torr reveal high temperature metallic to low temperature semiconducting transition. Interestingly, films deposited at 1 × 10−5 Torr reveal charge ordering, which is contributed to the magneli phase of TiO2. The present study suggests that functionality of TiO2 thin film based devices can be tuned by properly selecting the OPP and dopant concentration.

  6. Effect of compressive stress inducing a band gap narrowing on the photoinduced activities of sol-gel TiO2 films

    Ghazzal, Mohamed N.; Chaoui, N.; Genet, Michel; Gaigneaux, Eric M.; Robert, D.

    2011-01-01

    TiO2 thin films grown on different kinds of substrates were obtained by sol–gel process. X-ray diffraction revealed that the TiO2 lattice parameter c decreased continuously, indicating a continuous variation in the compressive stress, a negligible compressive stress of the film grown onto Soda-Lime Glass (SLG), medium compressive stress of the film grown onto BoroSilicate Glass (BSG) and large compressive stress of the film deposited onto the Quartz Substrate (QS). UV–Vis absorbance spectra e...

  7. Fabrication of Nb-Doped TiO2 Transparent Conducting Films by Postdeposition Annealing under Nitrogen Atmosphere

    Okazaki, Sohei; Ohkubo, Junpei; Nakao, Shoichiro; Hirose, Yasushi; Hitosugi, Taro; Hasegawa, Tetsuya

    2012-11-01

    Here, we report that highly conductive polycrystalline anatase Nb-doped TiO2 (TNO) thin films can be prepared via crystallization of amorphous precursors under N2 atmosphere. An optimized TNO film on a glass substrate exhibited a low resistivity of 8.4 ×10-4 Ω cm and an absorbance of 6% at a wavelength of 460 nm. These transport and optical properties were comparable to those of TNO films fabricated by vacuum annealing. This demonstrates the potential of TNO as an electrode for GaN-based light-emitting diodes.

  8. Preparation and photoelectrochemical performance of TiO2/Ag2Se interface composite film

    2009-01-01

    Coupling TiO2 with a narrow band gap semiconductor acting as the photosensitizer has attracted much attention in solar energy exploitation. In this work,the porous TiO2 film was first formed on the conducting glass plate (CGP) substrate by the decomposition of polyethylene glycol (PEG) mixing in titanium hydroxide sol at 450℃. Then,the TiO2/Ag2Se interface composite film was fabricated by interface reaction of AgNO3 with NaSeSO3 on the activated surface of porous TiO2 film. The results of SEM and XRD analyses indicated that the porous TiO2 layer was made up of the anatase crystal,and the Ag2Se layer was made up of congregative small particles that have low-temperature α-phase structure. Due to its efficient charge separation for the photo-induced electron-hole pairs,the TiO2/Ag2Se interface composite film as-prepared has good photovoltaic property and high photocurrent response for visible light,which have been confirmed by the photoelectrochemical measurements.

  9. Liquid phase deposition of mesoporous TiO2/DNA hybrid film: Characterization and photoelectrochemical investigation

    A photoelectroactive TiO2/DNA hybrid film was synthesized via the liquid phase deposition (LPD) process. Scanning electron microscopic (SEM) characterization showed that the compact TiO2 film was changed to a mesoporous structure when DNA was present in the deposition solution, which might be the result of TiO2 particles growing along the backbones of the double-helical structure of DNA molecules. Although UV absorption spectra and cyclic voltammograms indicated that the deposited TiO2 on the substrate surface was decreased in the presence of DNA, an enhanced photocurrent response was observed. The electrochemical impedance and cyclic voltammetric measurements using K3[Fe(CN)6] as a redox probe suggested that the mesoporous film provided a relatively more efficient electron transfer interface, which could improve the photoelectron transfer rate from the semiconducting film to the electrode and reduce the recombination of photoelectrons and holes. This results in an enhanced photocurrent. Even after long-term and continuous UV irradiation, the mesoporous film exhibited a promoted photoelectrochemical response. The promoted photoelectrocatalytic degradation of methylene blue was obtained on the TiO2/DNA composite film, which is consistent with the enhanced photocurrent, and this demonstrates that DNA behaved as a useful biomaterial for the synthesis of a photoelectroactive hybrid film with improved performance.

  10. Synthesis of polycarbonate-r-polyethylene glycol copolymer for templated synthesis of mesoporous TiO2 films.

    Patel, Rajkumar; Kim, Jinkyu; Lee, Chang Soo; Kim, Jong Hak

    2014-12-01

    We synthesized a novel polycarbonate Z-r-polyethylene glycol (PCZ-r-PEG) copolymer by solution polycondensation. Successful synthesis of PCZ-r-PEG copolymer was confirmed by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (1H-NMR), gel permeation chromatography (GPC), and transmission electron microscopy (TEM). PCZ-r-PEG copolymer was used as a structure-directing agent for fabrication of mesoporous thin film containing a titanium dioxide (TiO2) layer. To control the porosity of the resultant inorganic layer, the ratio of titanium(IV) isopropoxide (TTIP) to PCZ-r-PEG copolymer was varied. The structure and porosity of the resulting mesoporous films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. Mesoporous TiO2 films fabricated on an F-doped tin oxide (FTO) surface were used as photoanodes for quasi-solid-state dye-sensitized solar cells (qssDSSCs). The highest efficiency achieved was 3.3% at 100 mW/cm2 for a film thickness of 750 nm, which is high considering the thickness of TiO2 film, indicating the importance of the structure-directing agent. PMID:25971065

  11. Electrochromic multilayer films with enhanced stability based on polyoxometalate and TiO2

    Electrochromic multilayer films consisting of polyoxometalate (POM) cluster K6[P2W18].14H2O (P2W18), TiO2 and polyallylamine hydrochloride (PAH) were fabricated on quartz, silicon wafer and ITO substrates by the layer-by-layer self-assembly method. The multilayer films were characterized by UV-vis spectrum, scanning electron microscopy (SEM), cyclic voltammetry (CV) and chronoamperometric (CA) and in situ spectral electrochemical measurements. The interesting feature is that the electrochromic films can increase stability due to the presence of TiO2. The multilayer films exhibit high optical contrast, suitable response time and low operation potential. TiO2 is employed to enhance stability of the electrochromic multilayer films based on POMs by the layer-by-layer method, which gives valuable information for exploring new stable electrochromic materials.

  12. Effect of ion-beam assisted deposition on the film stresses of TiO2 and SiO2 and stress control

    Yu-Qiong Li; Hua-Qing Wang; Wu-Yu Wang; Zhi-Nong Yu; He-Shan Liu; Gang Jin

    2012-01-01

    Based on Hartmann-Shack sensor technique,an online thin film stress measuring system was introduced to measure the film stresses of TiO2 and SiO2,and comparison was made between the film stresses prepared respectively by the conventional process and the ion-beam assisted deposition.The effect of ion-beam assisted deposition on the film stresses of TiO2 and SiO2 was investigated in details,and the stress control methodologies using on-line adjustment and film doping were put forward.The results show that the film stress value of TiO2 prepared by ion-beam assisted deposition is 40 MPa lower than that prepared by conventional process,and the stress of TiO2 film changes gradually from tensile stress into compressive stress with increasing ion energy; while the film stress of SiO2 is a tensile stress under ion-beam assisted deposition because of the ion-beam sputtering effect,and the film refractive index decreases with increasing ion energy.A dynamic film stress control can be achieved through in-situ adjustment of the processing parameters based on the online film stress measuring technique,and the intrinsic stress of film can be effectively changed through film doping.

  13. Interface feature characterization and Schottky interfacial layer confirmation of TiO2 nanotube array film

    Li, Hongchao; Tang, Ningxin; Yang, Hongzhi; Leng, Xian; Zou, Jianpeng

    2015-11-01

    We report here characterization of the interfacial microstructure and properties of titanium dioxide (TiO2) nanotube array films fabricated by anodization. Field effect scanning electron microscopy (FESEM), X-ray diffraction (XRD), nanoindentation, atomic force microscopy (AFM), selected area electron diffraction (SAED), and high-resolution transmission electron microscopy (HRTEM) were used to characterize the interface of the film. With increasing annealing temperature from 200 °C to 800 °C, the interfacial fusion between the film and the Ti substrate increased. The phase transformation of the TiO2 nanotube film from amorphous to anatase to rutile took place gradually; as the phase transformation progressed, the force needed to break the film increased. The growth of TiO2 nanotube arrays occurs in four stages: barrier layer formation, penetrating micropore formation, regular nanotube formation, and nanofiber formation. The TiO2 nanotubes grow from the Schottky interface layer rather than from the Ti substrate. The Schottky interface layer's thickness of 35-45 nm was identified as half the diameter of the corresponding nanotube, which shows good agreement to the Schottky interface layer growth model. The TiO2 nanotube film was amorphous and the Ti substrate was highly crystallized with many dislocation walls.

  14. Dye-Sensitized Nanostructured TiO2 Film Based Photoconductor

    Kallioinen, Jani; Paraoanu, G S; Korppi-Tommola, Jouko

    2008-01-01

    Grooves were etched in a conductive layer of a conductive, transparent glass, and a nanoporous TiO2 film was deposited on both the conductive and nonconductive area. The width of the grooves was 100 $\\mu$m and 150 $\\mu$m. A transparent TiO2 film was dye-sensitized, covered with an electrolyte, and sandwiched with a cover glass. The conductivity of the dye-sensitized TiO2 film permeated with electrolyte was studied in the dark and under illumination, and was observed to be dependent on light intensity, wavelength and applied voltage. This study shows that dye-sensitized nanoporous films can be used as a wavelength dependent photoconductor.

  15. Evolution of Defect-Associated Subband Energy States in Nanocrystalline TiO2 Films on Si and Ge Substrates

    Kim, Jinwoo; Kim, Jinseo; Lee, Young-An; Seo, Hyungtak

    2013-10-01

    We identified the electronic states in the conduction- and valence-band edges associated with intrinsic defects in nanocrystalline TiO2 layers on Si and Ge substrates. This was accomplished through spectroscopic study with soft X-ray photoemission spectroscopy and visible-ultraviolet spectroscopic ellipsometry. The interpretation of the spectra based on molecular orbital (MO) theory well explains the origin of empty and occupied states of band edge in TiO2 with the correct assignment of MO states. The evolution of these band-edge states under thermal nanocrystalline growth and interfacial chemical mixing as a function of type of substrate was investigated, taking into consideration the asymmetric local bonding distortion and fast atomic diffusion at the grain boundary. The engineering solution to utilize TiO2 as a gate dielectric on Ge substrate is demonstrated by implanting SiON/Si interfacial layer. This study suggests that the control of electronically active defect density and energy level in nanoscale TiO2 thin films is strongly affected by thermal grain expansion and interfacial chemistry, depending on the semiconductor substrates used.

  16. Low-temperature atomic layer deposition of TiO2 thin layers for the processing of memristive devices

    Atomic layer deposition (ALD) represents one of the most fundamental techniques capable of satisfying the strict technological requirements imposed by the rapidly evolving electronic components industry. The actual scaling trend is rapidly leading to the fabrication of nanoscaled devices able to overcome limits of the present microelectronic technology, of which the memristor is one of the principal candidates. Since their development in 2008, TiO2 thin film memristors have been identified as the future technology for resistive random access memories because of their numerous advantages in producing dense, low power-consuming, three-dimensional memory stacks. The typical features of ALD, such as self-limiting and conformal deposition without line-of-sight requirements, are strong assets for fabricating these nanosized devices. This work focuses on the realization of memristors based on low-temperature ALD TiO2 thin films. In this process, the oxide layer was directly grown on a polymeric photoresist, thus simplifying the fabrication procedure with a direct liftoff patterning instead of a complex dry etching process. The TiO2 thin films deposited in a temperature range of 120–230 °C were characterized via Raman spectroscopy and x-ray photoelectron spectroscopy, and electrical current–voltage measurements taken in voltage sweep mode were employed to confirm the existence of resistive switching behaviors typical of memristors. These measurements showed that these low-temperature devices exhibit an ON/OFF ratio comparable to that of a high-temperature memristor, thus exhibiting similar performances with respect to memory applications

  17. The influence of metal interlayers on the structural and optical properties of nano-crystalline TiO 2 films

    Yang, Yong

    2012-03-01

    TiO 2-M-TiO 2 (M = W, Co and Ag) multilayer films have been deposited on glass substrates using reactive magnetron sputtering, then annealed in air for 2 h at 500°C. The structure, surface morphology and optical properties of the films have been studied using X-ray diffraction, Raman spectroscopy, atomic force microscopy and UV-vis spectroscopy. The TiO 2-W-TiO 2 and TiO 2-Co-TiO 2 films showed crystalline phases, whereas the TiO 2-Ag-TiO 2 films remained in the amorphous state. The crystallization temperature for the TiO 2-M-TiO 2 films decreased significantly compared with pure TiO 2 film deposited on quartz. Detailed analysis of the Raman spectra suggested that the crystallization of TiO 2-M-TiO 2 films was associated with the large structural deformation imposed by the oxidation of intermediate metal layers. Moreover, the optical band gap of the films narrowed due to the appearance of impurity levels as the metal ions migrated into the TiO 2 matrix. These results indicate that the insertion of intermediate metal layers provides a feasible access to improve the structural and optical properties of anatase TiO 2 films, leading to promising applications in the field of photocatalysis. © 2011 Elsevier B.V. All rights reserved.

  18. Hydrophilic property of SiO2/TiO2 double layer films

    The hydrophilicity of the SiO2(top)/TiO2(under) double layer films prepared by vacuum evaporation was investigated. The as-deposited SiO2/TiO2 double layer films showed very good hydrophilicity (water contact angle: ∼0o). Their hydrophilicity, however, is deteriorated by the organic contamination adsorbed on the film but the hydrophilicity can be recovered by UV light irradiation. TOF-SIMS (time-of-flight secondary-ion-mass-spectrometry) measurements revealed that the amount of organic compounds adsorbed on the films decreased with the UV light irradiation. Secondarily, the amount of both Si-OH and Ti-OH groups changed little by the UV light irradiation. Thus, it can be concluded that the hydrophilicity of the SiO2/TiO2 double layer films is due to the stable Si-OH groups and the photo-catalytic TiO2 underlayer maintains the hydrophilicity of the double layer films by decomposing organic contaminants on the film surface. This SiO2/TiO2 double layer film has been in practical use for the automobiles' exterior rear view mirrors

  19. Influences on photovoltage performance by interfacial modification of FTO/mesoporous TiO2 using ZnO and TiO2 as the compact film

    Highlights: → ZnO has been introduced as the compact layer in dye-sensitized solar cells by a facile spin-coating method. → The influences of ZnO and TiO2 compact films to photoelectron conversion process have been systematically investigated. → The duel effect to photoelectron conversion process of ZnO compact film has been found. → A new methodology of introducing an energy barrier at FTO/TiO2 interface rather than the surface of TiO2 electrode has been brought up. - Abstract: An effective ZnO compact film (ZCF) has been introduced at the interface of fluorine doped tin oxide (FTO) substrate and mesoporous TiO2 layer, and its effect on dye-sensitized solar cells (DSSCs) has been compared to that of conventional TiO2 compact film (TCF). The ZCF and TCF prepared by spin-coating method on FTO are characterized by energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and UV-vis spectrophotometer. The existence of TiO2 can suppress the recombination occurring at the interface of FTO/electrolyte, resulting in a higher Jsc and Voc than bare FTO. The ZCF creates an energy barrier between FTO substrate and mesoporous TiO2 layer, which not only reduces the electron back transfer from FTO to I3- in the electrolyte, but also leads to the accumulation of photogenerated electrons, and increases the electron density in the conduction band of TiO2. The device based on FTO/ZCF substrate remarkably improves Voc and FF, finally increases energy conversion efficiency by 13.1% compared to the device based on bare FTO and 4.7% compared to the counterpart based on FTO/TCF.

  20. Inkjet printed highly porous TiO2 films for improved electrical properties of photoanode.

    Bernacka-Wojcik, I; Wojcik, P J; Aguas, H; Fortunato, E; Martins, R

    2016-03-01

    The aim of presented work is to show the improvements obtained in the properties of TiO2 films for dye sensitized solar cells fabricated by inkjet printing using an innovative methodology. We describe the development and properties of TiO2-based inks used in a lab-scale printer, testing various commercial TiO2 pastes. The porosity of the deposited inkjet printed TiO2 films is much higher than using the conventional "doctor blade" deposition technique, as the ink solvent evaporates during the droplet fly from the nozzle to the substrate due to its picoliter volume and the applied heating of a printing stage (70°C). Thanks to higher surface area, the dye sensitized solar cells incorporating inkjet printed TiO2 film gave higher efficiencies (ηmax≈3.06%) than the more compact films obtained by the "doctor blade" method (ηmax≈2.56%). Furthermore, electrochemical analysis indicates that for whole tested thickness range, the inkjet printed layers have higher effective electron diffusion length indicating their better transport properties. PMID:26674237

  1. Synthesis of TiO2-doped SiO2 composite films and its applications

    Xiaojun Zhang; Huagui Zheng

    2008-10-01

    The TiO2-doped SiO2 composite films were prepared by two-step sol–gel method and then it was applied in the degradation of methylene red (MR) as photocatalysts. In XRD, FT–IR, and TEM investigations of these TiO2-doped SiO2 composite films, the titanium oxide species are highly dispersed in the SiO2 matrixes and exist in a tetrahedral form. And special attention has been focused on the relationship between the local structure of the titanium oxide species in the TiO2-doped SiO2 composite films and the photocatalytic reactivity in order to provide vital information for the design and application of such highly efficient photocatalytic systems in the degradation of toxic compounds diluted in a liquid phase.

  2. Influence of titanium precursor on the photocatalytic properties of TiO2 sprayed films under visible light

    Blaskov, V.; Shipochka, M.; Stambolova, I.; Vassilev, S.; Eliyas, A.; Stefanov, P.; Loukanov, A.

    2012-12-01

    Thin nano-sized TiO2 films were deposited on aluminum foil substrates by the spray pyrolysis method, using Ti(i-OPr)4 (TIP) and TiCl4 (TC) as precursors. The films were characterized by means of X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). According to the XRD patterns the as-deposited films appear to be amorphous. The thermal treatment at 400°C leads to the formation of anatase nano-crystallites. The XPS analyses showed that the Ti2p broad photoelectron peak of as-deposited TC films indicated a mixture of Ti3+ and Ti4+ oxidation states. After treatment at 400°C the Ti2p peak displays only Ti4+ oxidation state for both TIP and TC films. The number of hydroxyl groups on the surface is decreased after the thermal treatment. The photocatalytic activity of the films was studied towards degradation of azo dye Reactive Black 5 (RB5) as model wastewater pollutant under visible light illumination. It was found out that the films obtained from TC were more active than those obtained from TIP films. The thermally treated samples are better photocatalysts than those non-treated, because they posses anatase crystalline phase and stoichiometric TiO2. The TOC measurements showed minimal concentration of total organic carbon in the dye solution after 180 min of visible light irradiation.

  3. Effect of substrate type, dopant and thermal treatment on physicochemical properties of TiO2–SnO2 sol–gel films

    I Stambolova; V Blaskov; S Vassilev; M Shipochka; A Loukanov

    2012-08-01

    Thin nanocrystalline TiO2–SnO2 films (0–50 mol% SnO2) were prepared on quartz and stainless steel substrates by sol–gel coating method. The obtained films were investigated by XRD, Raman spectroscopy and XPS. The size of the nanocrystallites was determined by XRD–LB measurements. We ascertained that the increase of treatment temperature and concentration of SnO2 in the films favour the crystallization of rutile phase. The substrate type influences more substantially the phase composition of the TiO2–SnO2 films. It was established that a penetration of elements took place fromthe substrate into the films. TiO2 films deposited on quartz substrate include a Si which stabilizes anatase phase up to 600 °C. The films which are deposited on stainless steel substrate and treated at 700 °C show the presence of significant quantity of rutile phase. This phenomenon could be explained by the combined effect of Sn dopant as well as Fe and Cr, which also are penetrated in the films from the steel substrate. The titania films doped up to 10 mol% SnO2 on stainless steel possess only 12–17 nm anatase crystallites, whereas the TiO2–(10–50 mol%) SnO2 films contain very fine grain rutile phase (4 nm).

  4. 基于固定相二氧化钛薄膜的新型多重石英管分布式光催化反应器及其水处理应用%A Novel Multi-Tube Photoreactor with UV Light and Immobilized TiO2 Thin Film for Water Treatment

    谢一兵; 沈讯伟; 袁春伟

    2003-01-01

    A novel multi-tube photoreactor with 0.0188 m3 valid reaction volume was constructed in pilot-scale.This rectangular reactor consisted of 13 regularly distributed silica glass tubes coating with TiO2 thin film photo-catalyst. Total active area of TiO2 thin film is 0.3916m2. The ratio of surface area to volume achieves 20.8m-1.Photocatalytic experiment of phenol red demonstrates that the apparent reaction rate constant (k) is 0.074 65 h-1and 0.165 02 h-1 for reaction system with and without micro-bubbles mixing. The corresponding apparent quantumefficiency (φa) is 8.1771 × 10-7 g.J-1 and 4.9036 × 10-7 g.J-1, respectively. COD value of reactant could decreaseto 17 mg.L-1 and high performance liquid chromatography (HPLC) only shows two absorption peaks in 24 h pho-tocatalytic process time, so this photoreactor has good photomineralization effect. Experimental results reveal thatphotocatalytic destruction of organics is possible by using the multi-tube photoreactor.

  5. Photoelectrochemical Water Splitting of Nitrogen and Hydrogen Treated P25 TiO2 Films

    Zavodivker, Liat S.

    Photoelectrochemical data is reported for P25 TiO2 films deposited as a pristine film on FTO. The pristine P25 films show a photocurrent of 0.06 mA/cm2 and an onset potential of -0.5 V vs. Ag/AgCl. After TiCl4 Treatment to form a compact TiO 2 layer on the bottom and the surface layer, the TiCl4 sandwich films have a photocurrent of 0.19 mA/cm2 and an onset potential of -0.8 V. We have also investigated the effects of hydrogen treatment, ammonia treatment, and the combination of hydrogen treatment followed by ammonia treatment (co-treatment) on the photocurrent, the incident photon-to-current efficiency (IPCE), and the electron donor density of the P25 TiCl4 sandwich films. Treating the P25 films had almost no effect on the size and d-spacing of the particles, but EPR evidence, as well as color change, indicated the formation of N 2p nitrogen sites and oxygen vacancies (VO) for each film treatment. I-V data for the treated TiCl4 sandwich films show an increase in photocurrent from 0.19 mA/cm2 for the pristine P25 TiO2 film to 0.4 mA/cm 2 for the co-treated TiO2 film compared to 0.23 mA/cm 2 for hydrogen treatment and 0.25 mA/cm2 for ammonia treatment. For the P25 treated films, there is negligible increase of UV absorption in the visible for the singly treated films as well as the co-treated films. However, the improved photocurrent for the ammonia treated, hydrogen treated, and co-treated films may be explained by increased donor density. Mott-Schottky plots are used to characterize donor density, showing that the co-treated P25 TiCl4 sandwich films have an increased donor density over the nitrogen-treated P25 TiO2 and pristine P25 TiO2 films. The improved donor density of the treated P25 films over the untreated films may prove to be useful when completing future dye or semiconducting quantum dot sensitization experiments.

  6. Modification of physicochemical and thermal properties of starch films by incorporation of TiO2 nanoparticles.

    Oleyaei, Seyed Amir; Zahedi, Younes; Ghanbarzadeh, Babak; Moayedi, Ali Akbar

    2016-08-01

    In this research, potato starch and TiO2 nanoparticles (0.5, 1 and 2wt%) films were developed. Influences of different concentrations of TiO2 on the functional properties of nanocomposite films (water-related properties, mechanical characteristics, and UV transmittance) were investigated. XRD, FTIR, and DSC analyses were used to characterize the morphology and thermal properties of the films. The results revealed that TiO2 nanoparticles dramatically decreased the values of water-related properties (water vapor permeability: 11-34%; water solubility: 1.88-9.26%; moisture uptake: 2.15-11.18%). Incorporation of TiO2 led to a slight increment of contact angle and tensile strength, and a decrease in elongation at break of the films. TiO2 successfully blocked more than 90% of UV light, while opacity and white index of the films were enhanced. Glass transition temperature and melting point of the films were positively affected by the addition of TiO2 nanoparticles. The result of XRD study exhibited that due to a limited agglomeration of TiO2 nanoparticles, the mean crystal size of TiO2 increased. Formation of new hydrogen bonds between the hydroxyl groups of starch and nanoparticles was confirmed by FTIR spectroscopy. In conclusion, TiO2 nanoparticles improved the functional properties of potato starch film and extended the potential for food packaging applications. PMID:27132884

  7. Optical, electrical and dielectric properties of TiO 2-SiO 2 films prepared by a cost effective sol-gel process

    Vishwas, M.; Rao, K. Narasimha; Gowda, K. V. Arjuna; Chakradhar, R. P. S.

    2011-12-01

    Titanium dioxide (TiO 2) and silicon dioxide (SiO 2) thin films and their mixed films were synthesized by the sol-gel spin coating method using titanium tetra isopropoxide (TTIP) and tetra ethyl ortho silicate (TEOS) as the precursor materials for TiO 2 and SiO 2 respectively. The pure and composite films of TiO 2 and SiO 2 were deposited on glass and silicon substrates. The optical properties were studied for different compositions of TiO 2 and SiO 2 sols and the refractive index and optical band gap energies were estimated. MOS capacitors were fabricated using TiO 2 films on p-silicon (1 0 0) substrates. The current-voltage ( I- V) and capacitance-voltage ( C- V) characteristics were studied and the electrical resistivity and dielectric constant were estimated for the films annealed at 200 °C for their possible use in optoelectronic applications.

  8. Visible light active TiO2 films prepared by electron beam deposition of noble metals

    TiO2 films prepared by sol-gel method were modified by electron beam deposition of noble metals (Pt, Pd, and Ag). Effects of noble metals on the chemical and surface characteristics of the films were studied using XPS, TEM and UV-Vis spectroscopy techniques. Photocatalytic activity of modified TiO2 films was evaluated by studying the degradation of methyl orange dye solution under visible light UV irradiation. The result of TEM reveals that most of the surface area of TiO2 is covered by tiny particles of noble metals with diameter less than 1 nm. Broad red shift of UV-Visible absorption band of modified photocatalysts was observed. The catalytic degradation of methyl orange in aqueous solutions under visible light illumination demonstrates a significant enhancement of photocatalytic activity of these films compared with the un-loaded films. The photocatalytic efficiency of modified TiO2 films by this method is affected by the concentration of impregnating solution.

  9. Visible light active TiO 2 films prepared by electron beam deposition of noble metals

    Hou, Xing-Gang; Ma, Jun; Liu, An-Dong; Li, De-Jun; Huang, Mei-Dong; Deng, Xiang-Yun

    2010-03-01

    TiO 2 films prepared by sol-gel method were modified by electron beam deposition of noble metals (Pt, Pd, and Ag). Effects of noble metals on the chemical and surface characteristics of the films were studied using XPS, TEM and UV-Vis spectroscopy techniques. Photocatalytic activity of modified TiO 2 films was evaluated by studying the degradation of methyl orange dye solution under visible light UV irradiation. The result of TEM reveals that most of the surface area of TiO 2 is covered by tiny particles of noble metals with diameter less than 1 nm. Broad red shift of UV-Visible absorption band of modified photocatalysts was observed. The catalytic degradation of methyl orange in aqueous solutions under visible light illumination demonstrates a significant enhancement of photocatalytic activity of these films compared with the un-loaded films. The photocatalytic efficiency of modified TiO 2 films by this method is affected by the concentration of impregnating solution.

  10. Effect of Annealing Time Process on the pH Sensitivity of Spin-coated TiO2/ ZnO Bilayer Film

    Rahman, R. A.; Zulkefle, M. A.; Yusof, K. A.; Abdullah, W. F. H.; Rusop, M.; Herman, S. H.

    2015-11-01

    This paper presents an investigation on titanium dioxide (TiO2) and zinc oxide (ZnO) bilayer film, which is used as sensing membrane for extended-gate field effect transistor (EGFET) for pH sensing application. TiO2/ZnO thin films were deposited using sol-gel spin coating method on indium tin oxide (ITO) substrates. After the deposition, the bilayer films were annealed at constant temperatures which is 400 °C for 15, 30, 40 and 60 minutes. The sensitivity of the TiO2 thin film towards pH buffer solution was measured by dipping the sensing membrane in pH4, pH7 and pH10 buffer solution. By varying the annealing time, we found that the TiO2/ZnO thin film annealed at 400°C for 15 minutes gave the highest sensitivity compared to other annealing conditions, with the value of 64.87 mV/pH.

  11. Effects of filtered cathodic vacuum arc deposition (FCVAD) conditions on photovoltaic TiO2 films

    Highlights: • Titanium dioxide films were synthesized using the FCVAD technique. • Various FCVAD conditions were tested. • The TiO2 films were characterized. • The FCVAD condition effects on the film characteristics were studied. • The O2 pressure had the most important effect on the film quality. - Abstract: Titanium dioxide (TiO2) films for photovoltaic applications were synthesized using filtered cathodic vacuum arc deposition (FCVAD) technique. Various deposition conditions were tested for an optimal film formation. The conditions included the oxygen (O2) pressure which was varied from a base pressure 10−5 to 10−4, 10−3, 10−2 and 10−1 Torr, sample holder bias varied using 0 or −250 V, deposition time varied from 10, 20 to 30 min, and deposition distance varied from 1 to 3 cm. The deposited films were also annealed and compared with unannealed ones. The films under various conditions were characterized using optical microscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDS) and Raman spectroscopy techniques. The film transparency increased and thickness decreased to a nanoscale with increasing of the O2 pressure. The transparent deposited films contained stoichiometric titanium and oxygen under the medium O2 pressure. The as-deposited films were TiO2 containing some rutile but no anatase which needed annealing to form

  12. The Photoelectrocatalytic Properties of Thin TiO2 Electode

    Morozová, Magdalena; Klusoň, Petr; Krýsa, J.; Šolcová, Olga

    Sofia: -, 2009 - (Petrova, G.; Vayssilov, G.), s. 138 ISBN 978-954-323-558-2. [International Symposium Advanced Micro- and Mesoporous Materials /3./. Albena (BG), 06.09.2009-09.09.2009] R&D Projects: GA ČR(CZ) GD203/08/H032; GA ČR GA104/09/0694 Institutional research plan: CEZ:AV0Z40720504 Keywords : photoelectrocatalysis * thin electrode * photoelectrochemical behavior Subject RIV: CC - Organic Chemistry http://bg-conferences.org/micro2009_new_1/

  13. Photocatalytic sterilization of TiO2 films coated on Al fiber

    Photocatalytic TiO2 films were coated on Al fiber by sol-gel dip-coating method, and then annealed. The crystal structure and morphology of the films were performed by XRD, TEM and SEM. Photocatalytic sterilization of the films was investigated in O2 atmosphere through purifying the aqueous solution with facultative aerobe (Bacillus cereus), aerobe (Pseudomonas aeruginosa) and anaerobe (Staphylococcus aureus, Enterococcus faecalis and Escherichia coli). In the presence of O2, it benefits to generate O2·- and ·OH at the first stage of the photocatalytic reaction, while the excess O2 restrains the anaerobe from reproducing and accelerates the reproducing for the aerobe at the second stage of reaction. As a result, it was found that the crystal of TiO2 films is anatase phase and the films have excellent sterilization effect against facultative aerobe and anaerobe. Nevertheless, it only decreased the bioactivity against aerobe in a short time

  14. Photocatalytic activity and reusability study of nanocrystalline TiO2 films prepared by sputtering technique

    Barrocas, B.; Monteiro, O. C.; Jorge, M. E. Melo; Sério, S.

    2013-01-01

    The photocatalytic activity of nanocrystalline titanium dioxide (TiO2) films deposited on unheated glass substrates by DC reactive magnetron sputtering at different oxygen partial pressures was tested on the decolorization of Rhodamine 6G (Rh6G) aqueous solutions. The dye photodecolorization process was studied considering the influence of the crystallinity and preferred orientation of growth of the prepared films. It was found that the higher photocatalytic activity was achieved by the film with preferred orientation of growth along the (1 0 1) crystal direction and showing a vestigial rutile phase in a mainly anatase phase. The recycling catalytic ability of the TiO2 films was also evaluated and a promising photocatalytic performance has been revealed with a very low variation of the decay rate after five consecutive usages. Structural and morphological characterization revealed high photochemical stability of the films after successive photodegradations assays.

  15. Effect of Oxygen Partial Pressure on the Electrical and Optical Properties of DC Magnetron Sputtered Amorphous TiO2 Films

    M. Chandra Sekhar

    2013-01-01

    Full Text Available Titanium dioxide (TiO2 thin films were deposited on p-Si (100 and Corning glass substrates held at room temperature by DC magnetron sputtering at different oxygen partial pressures in the range 9 × 10−3–9 × 10−2 Pa. The influence of oxygen partial pressure on the structural, electrical, and optical properties of the deposited films was systematically studied. XPS studies confirmed that the film formed at an oxygen partial pressure of 6×10−2 Pa was nearly stoichiometric. TiO2 films formed at all oxygen partial pressures were X-ray amorphous. The optical transmittance gradually increased and the absorption edge shifted towards shorter wavelengths with the increase of oxygen partial pressure. Thin film capacitors with configuration of Al/TiO2/p-Si have been fabricated. The results showed that the leakage current density of films formed decreased with the increase of oxygen partial pressure to 6×10−2 Pa owing to the decrease in the oxygen defects in the films thereafter it was increased. The current transport mechanism in the TiO2 thin films is shown to be Schottky effect and Fowler-Nordheim tunnelling currents.

  16. Transparent and conducting TiO2:Nb films made by sputter deposition : Application to spectrally selective solar reflectors

    Maghanga, Christopher M.; Jensen, Jens; Niklasson, Gunnar A.; Granqvist, Claes-Göran; Mwamburi, M.

    2010-01-01

    Transparent and conducting thin films of TiO2:Nb were prepared on glass and aluminum substrates by dual-target reactive DC magnetron sputtering in an Ar+O-2 plasma. The Nb content lay between 0 and 4.9 at% as determined by ion beam analyses. X-ray diffraction showed that vacuum annealing at 450 degrees C led to crystallinity and prevalence of the anatase phase. The influence of Nb doping was studied with regard to structural, optical, and electrical data. Optical constants were determined fro...

  17. Variations in the structural, optical and electrochemical properties of CeO2-TiO2 films as a function of TiO2 content

    Alcohol based sols of cerium chloride (CeCl3.7H2O) and titanium propoxide (Ti(OPr)4) in ethanol mixed in different mole ratios have yielded mixed oxide films on densification at 500 deg. C. The reversibility of the intercalation/deintercalation reactions has shown electrochemical stability of the films. Addition of TiO2 in an equivalent mole ratio manifests in producing highly transparent films with appreciable ion storage capacity. The electrochemical studies have revealed the significant role of TiO2 in controlling the ion storage capacity of the films, as it tends to induce the disorder. In addition, the films prepared from an aged sol are observed to exhibit a much higher ion storage capacity than the films deposited using the as-prepared sol. The X-ray photoelectron spectroscopic studies have provided information on the variation of Ce4+/Ce3+ ratio as a function of increased TiO2 content in the films. This study has led to a better understanding of the increased ion storage capacity with the increased TiO2 proportion. The transmission electron microscopic study has demonstrated the presence of CeO2 nanograins even in films, which are amorphous to X-rays. Elucidation of the structural, optical and electrochemical features of the films has yielded information on aspects relevant to their usage in transmissive electrochromic devices. The films have been found to exhibit properties that can find application as counter electrode in electrochromic smart windows in which they are able to retain their transparency under charge insertion, high enough for practical uses. Also, the fastest coloration-bleaching kinetics for the primary electrochromic electrode (WO3) working in combination with Ce/Ti (1:1) electrode stimulates the use of latter in electrochromic windows (ECWs)

  18. Variations in the structural, optical and electrochemical properties of CeO 2-TiO 2 films as a function of TiO 2 content

    Verma, Amita; Joshi, Amish G.; Bakhshi, A. K.; Shivaprasad, S. M.; Agnihotry, S. A.

    2006-05-01

    Alcohol based sols of cerium chloride (CeCl 3·7H 2O) and titanium propoxide (Ti(OPr) 4) in ethanol mixed in different mole ratios have yielded mixed oxide films on densification at 500 °C. The reversibility of the intercalation/deintercalation reactions has shown electrochemical stability of the films. Addition of TiO 2 in an equivalent mole ratio manifests in producing highly transparent films with appreciable ion storage capacity. The electrochemical studies have revealed the significant role of TiO 2 in controlling the ion storage capacity of the films, as it tends to induce the disorder. In addition, the films prepared from an aged sol are observed to exhibit a much higher ion storage capacity than the films deposited using the as-prepared sol. The X-ray photoelectron spectroscopic studies have provided information on the variation of Ce 4+/Ce 3+ ratio as a function of increased TiO 2 content in the films. This study has led to a better understanding of the increased ion storage capacity with the increased TiO 2 proportion. The transmission electron microscopic study has demonstrated the presence of CeO 2 nanograins even in films, which are amorphous to X-rays. Elucidation of the structural, optical and electrochemical features of the films has yielded information on aspects relevant to their usage in transmissive electrochromic devices. The films have been found to exhibit properties that can find application as counter electrode in electrochromic smart windows in which they are able to retain their transparency under charge insertion, high enough for practical uses. Also, the fastest coloration-bleaching kinetics for the primary electrochromic electrode (WO 3) working in combination with Ce/Ti (1:1) electrode stimulates the use of latter in electrochromic windows (ECWs).

  19. Cascade structure of TiO2/ZnO/CdS film for quantum dot sensitized solar cells

    Highlights: → Solar cells based on a cascade structure of TiO2/ZnO/CdS photoanode are fabricated. → ZnO is one-step deposited on TiO2 layer by ultrasonic spray pyrolysis technique. → As-prepared cell achieves a power conversion efficiency of 1.56%. - Abstract: Quantum dot sensitized solar cells based on cascade structure of TiO2/ZnO/CdS electrode and polysulfide electrolyte were fabricated. The ZnO layer was deposited on screen-printed TiO2 layer by ultrasonic spray pyrolysis method. The structure, morphology and impedance of TiO2/ZnO film photoanode and the photovoltaic performance of TiO2/ZnO/CdS cell were investigated. It is found that the short circuit current density and conversion efficiency are significantly improved by the introduction of ZnO layer into TiO2/CdS film. A power conversion efficiency of about 1.56% has been obtained for TiO2/ZnO/CdS cell, which is about 57% higher than that for TiO2/CdS cell (0.99%). The formation of an inherent energy barrier between TiO2 and CdS films and the passivation of surface traps on the TiO2 film caused by the introduction of ZnO layer, which reduces the charge recombination and favors the electron transport, should be mainly responsible for the performance enhancement of TiO2/ZnO/CdS cell.

  20. Nanostructured Fe2O3/TiO2 thick films prepared by screen printing

    Obrad S. Aleksic

    2013-09-01

    Full Text Available Nanostructured single layered (pure TiO2, pure α-Fe2O3 and mixed Fe2O3/TiO2 with two different oxide ratios, 2 : 3 and 3 : 2 and double layered (TiO2 layer over a Fe2O3 layer thick films have been fabricated by screen printing technology on a glass substrate. The pastes used for film preparation were obtained by adding an organic vehicle to the oxide powders together with a small percentage of binding glass frit. Samples were dried up to 100 °C and sintered at 650 °C/60 minutes. Structural, morphological and optical studies have been carried out using XRD, SEM analyses and UV/Vis spectroscopy. The prepared pure and mixed Fe2O3/TiO2 thick films had a homogenous nanostructure without secondary phases. Indirect band gaps were determined from the measured transmission spectra and the obtained values are in the range of literature data.

  1. Photocatalysts of Cr Doped TiO2 Film Prepared by Micro Arc Oxidation

    Li Wan; Jian-feng Li; Jia-you Feng; Wei Sun; Zong-qiang Mao

    2008-01-01

    A series of Cr doped TiO2 films were prepared by micro arc oxidation (MAO) using an electrolyte of Na3PO4+K2Cr2O7. X-ray diffraction and scanning electron microscopy revealed that the films mainly consisted of anatase phase with a porous surface morphology. The films have an excellent photocatalytic effect for degradation of methylene blue and decomposition of water under visible light illumination. This arises from the formation of Cr3+/Cr4+ and oxygen vacancy energy levels owing to Cr doping. The former reduces the electron-hole recombination chance, while the latter generates a new gap between the conduction band (CB) and valence band (VB) of TiO2, which lowers the photo energy of the excited electron in the VB to the oxygen vacancy states. The mechanisms for film synthesis during the MAO process are also presented.

  2. Photocatalytic activity of erbium-doped TiO2 nanoparticles immobilized in macro-porous silica films

    Highlights: ► Erbium-doped TiO2 nanoparticles were immobilized on macro-porous silica films. ► The films were obtained by a phase separation process. ► The samples exhibited photo-catalytic activity under visible light. ► The sensitization of TiO2 was attributed to a red shift in the TiO2 band-gap. -- Abstract: A macro-porous silica film served as mechanical support to immobilize TiO2 nanoparticles, which were doped with erbium. The films and the nanoparticles were prepared by sol–gel route. The nanoparticles exhibited photocatalytic activity under visible light. We obtained a degradation rate of methylene blue that followed first order kinetics. The sensitization of the nanoparticles to visible light was attributed to a red shift in the band-gap of the TiO2 due to the addition of erbium ions.

  3. Influência do tipo de ácido e tempo de envelhecimento na atividade fotocatalítica de filmes finos de TiO2

    Liana Key Okada Nakamura

    2011-01-01

    Full Text Available TiO2 thin films were prepared by the sol-gel method using different acids (HCl and HAc, with a parallel evaluation of the gel ageing effects on the film properties. After the thermal treatments, the resulting materials were characterized through gravimetric analysis, UV-VIS spectrophotometry (from which optical parameters such as band gap was derived, XRD, morphological surface analysis (AFM and photocatalytic activity. The majority of the obtained thin films parameters were similar independent of the acid type and the ageing time of the gel. Nevertheless, a visible effect of the surface morphology properties on the films and their photocatalytic activity was observed.

  4. 前驱体浓度对纳米TiO2薄膜生长及光激发特性的影响%Effect of Reaction Parameters on Growth and Absorption Excitation Characteristics of Nanometer TiO2 Thin Films

    梅景红

    2013-01-01

    Use Ti (SO4)2 as the raw material and anhydrous sodium carbonate (Na2CO3) as the additive, TiO2 thin films are prepared by using the method of hydrothermal synthesis on the substrate of titanium successfully.The law of concentrations effect on the growth characteristics of titanium dioxide thin film、the crystallization and phase composition has been studied systematically by using the method of X-ray diffraction (XRD) and Scanning electron microscopy (SEM), the dynamics mechanism has been analyzed;The excitation characteristics of prepared TiO2 thin films has been studied by using photoluminescence spectroscopy (PL), and the laws of effect has been theoretical explained through the micro-mechanism.%  以Ti (SO4)2为原料,无水碳酸钠(Na2CO3)为添加剂,采用水热合成法在钛合金基底上成功制备了锐钛矿相的纳米TiO2薄膜。利用X射线衍射(XRD)、扫描电子显微镜(SEM)等测试手段系统的研究了前驱体浓度对纳米TiO2薄膜生长特性、结晶特性和相组成的影响规律;利用光致激发光谱(PL)研究了所制备TiO2薄膜的光激发特性,并通过微观机制对其影响规律进行了理论解释。

  5. Characteristics of TiO2/ZnO bilayer film towards pH sensitivity prepared by different spin coating deposition process

    Rahman, Rohanieza Abdul; Zulkefle, Muhammad Al Hadi; Abdullah, Wan Fazlida Hanim; Rusop, M.; Herman, Sukreen Hana

    2016-07-01

    In this study, titanium dioxide (TiO2) and zinc oxide (ZnO) bilayer film for pH sensing application will be presented. TiO2/ZnO bilayer film with different speed of spin-coating process was deposited on Indium Tin Oxide (ITO), prepared by sol-gel method. This fabricated bilayer film was used as sensing membrane for Extended Gate Field-Effect Transistor (EGFET) for pH sensing application. Experimental results indicated that the sensor is able to detect the sensitivity towards pH buffer solution. In order to obtained the result, sensitivity measurement was done by using the EGFET setup equipment with constant-current (100 µA) and constant-voltage (0.3 V) biasing interfacing circuit. TiO2/ZnO bilayer film which the working electrode, act as the pH-sensitive membrane was connected to a commercial metal-oxide semiconductor FET (MOSFET). This MOSFET then was connected to the interfacing circuit. The sensitivity of the TiO2 thin film towards pH buffer solution was measured by dipping the sensing membrane in pH4, pH7 and pH10 buffer solution. These thin films were characterized by using Field Emission Scanning Electron Microscope (FESEM) to obtain the surface morphology of the composite bilayer films. In addition, I-V measurement was done in order to determine the electrical properties of the bilayer films. According to the result obtained in this experiment, bilayer film that spin at 4000 rpm, gave highest sensitivity which is 52.1 mV/pH. Relating the I-V characteristic of the thin films and sensitivity, the sensing membrane with higher conductivity gave better sensitivity.

  6. Laser synthesis of hierarchically organized nanostructured TiO2 films on microfibrous carbon paper substrate: Characterization and electrocatalyst supporting properties

    Wang, Youling; Tabet-Aoul, Amel; Mohamedi, Mohamed

    2015-12-01

    Titanium dioxide is cheap, non-toxic, exhibits a high mechanical resistance, very stable in acidic and oxidative environments is being studied as alternative to carbon as catalyst support in low-temperature fuel cells. Herein, via pulsed laser deposition, various morphologies of TiO2 thin films are synthesized at room temperature onto conductive microfibrous carbon paper substrate, which is the type of substrate, employed in energy storage and conversion devices. TiO2 films deposited under vacuum and in the presence of mild pressure of oxygen are very smooth and dense. Instead, TiO2 films deposited in the presence of helium atmosphere are of porous structures and vertically aligned. An increase in the helium pressure leads to the formation of forest-like vertically aligned nanostructures. Micro-Raman spectroscopy reveals that the films are amorphous and of rutile phase. X-ray photoelectron spectroscopy shows that Ti is in fully oxidized state of Ti4+. The electrocatalytic supporting properties to Pt are investigated in H2SO4 and O2-saturated H2SO4 solution. It is found that regardless of the film morphology, all the synthesized TiO2 films dramatically increase the electroactive surface area of Pt and enhance its electroactivity towards oxygen reduction reaction as compared with bare Pt electrode.

  7. Conductive and transparent multilayer films for low-temperature TiO2/Ag/SiO2 electrodes by E-beam evaporation with IAD

    Chiu, Po-Kai; Lee, Chao-Te; Chiang, Donyau; Cho, Wen-Hao; Hsiao, Chien-Nan; Chen, Yi-Yan; Huang, Bo-Ming; Yang, Jer-Ren

    2014-01-01

    Conductive and transparent multilayer thin films consisting of three alternating layers (TiO2/Ag/SiO2, TAS) have been fabricated for applications as transparent conducting oxides. Metal oxide and metal layers were prepared by electron-beam evaporation with ion-assisted deposition, and the optical and electrical properties of the resulting films as well as their energy bounding characteristics and microstructures were carefully investigated. The optical properties of the obtained TAS material ...

  8. Contribution of thickness dependent void fraction and TiSi{sub x}O{sub y} interlayer to the optical properties of amorphous TiO2 thin films

    Zhang, Fan; Zhang, Rong-Jun, E-mail: rjzhang@fudan.edu.cn; Zheng, Yu-Xiang, E-mail: yxzheng@fudan.edu.cn; Xu, Zi-Jie; Zhang, Dong-Xu; Wang, Zi-Yi; Yu, Xiang; Chen, Liang-Yao

    2013-12-02

    The optical properties of TiO{sub 2} thin films prepared by electron beam evaporation were studied by spectroscopic ellipsometry and analyzed quantitatively using effective medium approximation theory and an effective series capacitance model. The refractive indices of TiO{sub 2} are essentially constant and approach to those of bulk TiO{sub 2} for films thicker than 40 nm, but drop sharply with a decrease in thickness from 40 to 5.5 nm. This phenomenon can be interpreted quantitatively by the thickness dependence of the void fraction and interfacial oxide region. The optical band gaps calculated from Tauc law increase with an increase of film thickness, and can be attributed to the contribution of disorder effect. - Highlights: • Amorphous TiO{sub 2} thin films fabricated on Si substrate by electron beam evaporation • The refractive index and band gap are obtained from spectroscopic ellipsometry. • The refractive index decreases with decreasing film thickness. • Effective medium approximation theory and effective series capacitance model introduced • A band gap increases gradually with an increase in film thickness.

  9. Multicolor photochromism of silver-containing mesoporous films of amorphous or anatase TiO2

    Mesoporous TiO2 films loaded with silver nanoparticles grown photocatalytically, which are initially brown, change their color under visible laser irradiations. In this article, we compare the multicolor photochromisms of amorphous and anatase phases of TiO2. The mesoporous films are impregnated with silver salt and then exposed to a low-intensity UV laser light to grow silver nanoparticles. The Ag–TiO2 films are then exposed to visible laser beams, and the influences of several exposure parameters on the photochromic behavior are examined. Most of the previous studies have reported a poor stability of the photoinduced colors under day light or even in the dark, and few of them demonstrated the ability to get various colors on the same sample. These inconveniences limit the application field of such materials. On the other hand, except in our previous studies, only crystalline TiO2 is generally used, in its anatase or rutile phase. In this article we show that mesoporous films of amorphous and anatase phases of TiO2 respond in an efficient manner to light excitation and that multiple colors can be obtained on both kinds of films. For the first time on such Ag–TiO2 films we show that the various photoinduced colors are stable over considerable months. Visible intensity is shown to have a significant influence on the film behavior, which was not identified in previous studies. The laser-induced spectral changes are also shown to depend on the incident laser polarization. The photochromic behaviors are characterized in terms of color changes and spectral variations. The reproducibility of the photochromic process along reduction/oxidation cycles is demonstrated, and the stability of different laser-induced colors is reported on 6-month-old samples

  10. Effective CH4 production from CO2 photoreduction using TiO2/x mol% Cu–TiO2 double-layered films

    Highlights: • Photoreduction of CO2 to CH4 on TiO2/x mol% Cu–TiO2 double layered films. • CH4 gas generated from the photoreduction of CO2 increased on TiO2/Cu–TiO2 films. • CH4 gas on TiO2/5.0 mol% Cu–TiO2 film was twice higher than on the TiO2/TiO2 film. • Recombination of photogenerated electron–hole pairs inhibited on TiO2/Cu–TiO2 film. - Abstract: This study examined the photoreduction of CO2 to CH4 over TiO2/x mol% Cu–TiO2 double layered films. x mol% Cu-incorporated TiO2 nano-sized powders were prepared using a conventional solvothermal method. The prepared powders were fabricated as TiO2 (bottom)/Cu–TiO2 (top) double layered films for applications to the photoreduction of CO2. The amount of CH4 generated from the photoreduction of CO2 with H2O increased remarkably over the TiO2/Cu–TiO2 double layered films compared to the TiO2/TiO2 double-layered films. In particular, the amount of CH4 gas evolved over the TiO2/5.0 mol% Cu–TiO2 doubled layered film was twice as high as that produced over the TiO2/TiO2 double layered film. A proposed model suggested that the photoactivity over the TiO2/Cu–TiO2 double layered films can be enhanced by effective charge separation and inhibited recombination of the photogenerated electron–hole (e−/h+) pairs during interfacial transfer between TiO2 and Cu–TiO2

  11. Initial deposition and electron paramagnetic resonance defects characterization of TiO2 films prepared using successive ionic layer adsorption and reaction method

    Successive ionic layer adsorption and reaction (SILAR) technique was considered promisingly to deposit ultra thin titanium dioxide (TiO2) films under ambient condition. In this paper, the growth process, structures and paramagnetic defects of the films were characterized by complementary techniques of atomic force microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and electron paramagnetic resonance spectroscopy. The results indicate that on glass substrate the SILAR TiO2 film nucleates in an island mode within the initial five deposition cycles but grows in a layer-by-layer mode afterwards. The growth rate was measured as 4.6 Å/cycle. In the as-deposited films, a kind of paramagnetic defects is detected at g (2.0029) and it can be attributed to oxygen vacancies. These as-received oxygen vacancies could be annealed out at 473 K. Ultraviolet irradiation on the as-deposited films can also decrease the density of the defects. The relative mechanisms on the phenomenon were discussed in this paper. - Highlights: ► TiO2 films are deposited on glass at 25 °C by successive ionic layer adsorption and reaction method with a rate of 4.6 Å/cycle. ► The films nucleate in an island mode initially but grow in a layer mode afterwards. ► The SILAR TiO2 films nucleation period is five cycles. ► Electron paramagnetic resonance spectroscopy shows that TiO2 films paramagnetic defects are attributed to oxygen vacancies. ► They will decrease by anneal or ultraviolet radiation and form hydroxyl or superoxide radicals.

  12. Degradation of Pollutant and Antibacterial Activity of Waterborne Polyurethane/Doped TiO2 Nanoparticle Hybrid Films

    QIU Shan; DENG Fengxia; XU Shanwen; LIU Peng; MIN Xinmin; MA Fang

    2015-01-01

    The waterborne polyurethane/doped TiO2 nanoparticle hybrid films were prepared. Nd, I doped TiO2 was prepared with a 50 nm particle sizefi rstly. The hybridfi lm was prepared by mixing doped TiO2 with waterborne polyurethane, followed by heat treatment. The presence and nanometric distribution of doped TiO2 nanoparticles in prepared membranes is evident according to SEM images. The photocatalytic activities of doped TiO2 were signifi cantly enhanced compared with pure TiO2 powders. After the hybridfi lm fabrication, the photocatalytic activities were almost the same as the pure catalysts withkMB of 0.046. In the antibacterial testing, the hybridfi lms can inhibitE. coli growth. A signifi cant decrease in membranefl uidity and increase of permeability ofE. coli were observed.

  13. Photoactive TiO2 Films Formation by Drain Coating for Endosulfan Degradation

    Natalia Tapia-Orozco

    2013-01-01

    Full Text Available Heterogeneous photocatalysis is an advanced oxidation process in which a photoactive catalyst, such as TiO2, is attached to a support to produce free radical species known as reactive oxygen species (ROS that can be used to break down toxic organic compounds. In this study, the draining time, annealing temperature, and draining/annealing cycles for TiO2 films grown by the drain coating method were evaluated using a 23 factorial experimental design to determine the photoactivity of the films via endosulfan degradation. The TiO2 films prepared with a large number of draining/annealing cycles at high temperatures enhanced (P>0.05 endosulfan degradation and superoxide radical generation after 30 minutes of illumination with UV light. We demonstrated a negative correlation (R2=0.69; P>0.01 between endosulfan degradation and superoxide radical generation. The endosulfan degradation rates were the highest at 30 minutes with the F6 film. In addition, films prepared using conditions F1, F4, and F8 underwent an adsorption/desorption process. The kinetic reaction constants, Kapp (min−1, were 0.0101, 0.0080, 0.0055, 0.0048, and 0.0035 for F6, F2, F5, F3, and F1, respectively. The endosulfan metabolites alcohol, ether, and lactone were detected and quantified at varying levels in all photocatalytic assays.

  14. TiO2-聚苯胺复合膜的光电化学%The Photoelectrochemistry of TiO2-Polyaniline Composite Film

    黄怀国; 郑志新; 罗瑾; 张红平; 吴玲玲; 林仲华

    2001-01-01

    A TiO2 and polyaniline (PANI) composite film was obtained by electrochemical methods. The SEM image of the composite film showed that the PANI film is almost completely covered with TiO2. The spectra of photocurrent for the TiO2-PANI composite film , which overlaps the TiO2 film and PANI film, showed that the composite film is able to have higher conversion efficiency. The spectra of photocurrent for the TiO2-PANI composite film were different from these of TiO2 film photosensitized by PANI. The bandgap energy of TiO2 film on partially-oxidized PANI film was determined as 3.0 eV by the threshold energy of photocurrent band for TiO2. The spectra of photocurrent for partially-oxidized PANI film electrode suggested that it has the characteristics of sub-band gap spectra of photocurrent and followed Fowler rule(1/2~hν). The bandgap energy of insulating matrix in partially-oxidized PANI is determined as 3.33 eV by the Flowler plots, and the insulating matrix in partially-oxidized PANI was verified to be reduced PANI. The flat-band potentials, in the order of 0.87 V vs. NHE for partially-oxidized PANI and 0.09V vs. NHE for TiO2-PANI composite film in 1.0 mol/L HClO4 solution,were obtained from Mott-Schottky plots. The doping content of partially-oxidized PANI and TiO2-PANI composite film are 5.3×1018 cm-3 and 9.1×1019 cm-3, respectively. The photoelectrochemical process of TiO2-PANI composite film is interpreted and the energy diagram is proposed. The TiO2-PANI composite film can be well used for treating the wastewater, for example, containing phenol.%利用电化学方法制备了TiO2-聚苯胺(PANI)复合膜.该膜具有比TiO2或PANI膜更宽的吸收谱区,并且不同于利用聚苯胺光敏化的TiO2膜,表现为两者复合材料膜的性质.扫描电镜图表明,TiO2微粒不完全覆盖着PANI膜.根据TiO2微粒光电流谱带的阈值能可得复盖在部分氧化态聚苯胺膜上的TiO2微粒的禁带宽度为3.0 eV.部分氧化态聚苯胺

  15. Nanostructured TiO2 films for dye-sensitized solar cells prepared by the sol-gel method.

    Jin, Young Sam; Kim, Kyung Hwan; Park, Sang Joon; Yoon, Hyon Hee; Choi, Hyung Wook

    2011-12-01

    TiO2 films were prepared on glass substrates using the sol-gel process for a dye-sensitized solar cell application. The TiO2 sol was prepared using hydrolysis/polycondensation. Titanium (IV) Tetra Isopropoxide (TTIP) was used as precursor and Nitric acid (HNO3) was used as a catalyst for the peptization. The crystal structure and morphology of the prepared materials were characterized by XRD, and an SEM. The observations confirmed the nanocrystalline nature of the TiO2. The reaction parameters, such as the catalyst concentrations, the calcination time, and the calcination temperature were varied during the synthesis in order to achieve nanosize TiO2 particles. The prepared TiO2 particles were coated onto FTO glass using a screen printing technique. The prepared TiO2 films were characterized by UV-vis. The TiO2 particles calcinated at low temperatures showed an anatase phase they grew into a rutile phase when the calcination temperature increased. The size and structure of the TiO2 particles were adjusted to specific surface areas. It was found that the conversion efficiency of the DSSC was highly affected by the properties of the TiO2 particles. PMID:22409037

  16. Effect of N-Doping on Absorption and Luminescence of Anatase TiO2 Films

    XIANG Xia; SHI Xiao-Yan; GAO Xiao-Lin; JI Fang; WANG Ya-Jun; LIU Chun-Ming; ZU Xiao-Tao

    2012-01-01

    Anatase TiO2 films are deposited on glass substrates at different oxygen partial pressures of 0.8-1.6 Pa.Room temperature N ion implantation is conducted in the films at ion fluences up to 5 × 1017 ions/cm2.UV-visible absorption and photoluminescence (PL) are investigated.With the increase of N ion fluences,the band gap of TiO2 decreases and the absorbance increases.X-ray photoelectron spectroscopy (XPS) confirms the formation of O-Ti-N nitride after implantation,resulting in the red shift of the band gap.The PL intensity of the deposited films increases with the increasing oxygen partial pressure and decreases remarkably due to the irradiation defects induced by ion implantation.%Anatase TiO2 films are deposited on glass substrates at different oxygen partial pressures of 0.8-1.6Pa. Room temperature N ion implantation is conducted in the films at ion fluences up to 5 ×1017 ions/cm2. UV-visible absorption and photoluminescence (PL) are investigated. With the increase of N ion Buences, the band gap of TiO2 decreases and the absorbance increases. X-ray photoelectron spectroscopy (XPS) confirms the formation of O-Ti-N nitride after implantation, resulting in the red shift of the band gap. The PL intensity of the deposited films increases with the increasing oxygen partial pressure and decreases remarkably due to the irradiation defects induced by ion implantation.

  17. Preparation of cerium-doped TiO2 film on 304 stainless steel and its bactericidal effect in the presence of sulfate-reducing bacteria (SRB)

    Cerium-doped TiO2 film with bactericidal activity was prepared on 304 stainless steel by a sol-gel process. The doped cerium ions were identified to have retarding effect on the phase transition from amorphous TiO2 to anatase TiO2. This effect was interpreted as the distortion of crystal lattice, due to the introduction of cerium ions into the crystal structure of TiO2. The absorption band edge of cerium-doped TiO2 film has a red shift compared with that of pure TiO2 film in UV-vis spectra. The films covered with sulfate-reducing bacteria (SRB) medium were exposed to sunlight for 6 h and the bactericidal efficiency was evaluated with most probable number technique. It was found that the bactericidal efficiency of cerium-doped TiO2 film and pure TiO2 film were 95% and 85%, respectively.

  18. Biocompatible Eu-doped TiO2 nanodot film with in situ protein adsorption characterization property

    Europium (Eu) doped TiO2 nanodot films were prepared through a phase-separation-induced self-assembly method. Eu was doped to impart the nanodots with luminescence property so that the protein adsorption could be in situ characterized quantitatively. Bovine serum albumin (BSA) was adsorbed on the surface of Eu-doped titanium nanodot films. It was found that the photo luminescence intensity at 616 nm decreased with the increase of BSA adsorption time. Also, Eu-doped TiO2 nanodot films showed good biocompatibility. These results suggested that Eu-doped TiO2 nanodot films could provide a feasible in situ way to evaluate protein adsorption if prepared on the surface of bioimplants. - Highlights: • Simple preparation of Eu doped TiO2 nanodot films • Eu doped nanodot films show good biocompatibility. • Easy in situ evaluation of protein adsorption via photo luminescence of Eu

  19. Photocatalytic Properties of Columnar Nanostructured TiO2 Films Fabricated by Sputtering Ti and Subsequent Annealing

    Zhengjun Zhang; Liping Xing; Zhengcao Li

    2012-01-01

    Columnar nanostructured TiO2 films were prepared by sputtering Ti target in pure argon with glancing angle deposition (GLAD) and subsequent annealing at 400°C for different hours in air. Compared with sputtering TiO2 target directly, sputtering Ti target can be carried out under much lower base pressure, which contributes to obtaining discrete columnar nanostructures. In the present study, TiO2 films obtained by annealing Ti films for different hours all kept discrete columnar structures as t...

  20. Preparation and crystalline phase of a TiO2 porous film by anodic oxidation

    WANG Wei; TAO Jie; ZHANG Weiwei; TAO Haijun; WANG Ling

    2005-01-01

    Anatase titanium dioxide is an active photocatalyst, but it is difficult to immobilize on the substrate. A crystalline TiO2 porous film was prepared directly on the surface of pure titanium by anodic oxidation in this work. Constant voltage and constant current anodic oxidation were adopted with sulphuric acid used as the electrolyte, pure titanium as the anode and copper as the cathode. The morphology and structure of the porous film on the substrate were analyzed with the aid of Field Emission Scanning Electron Microscopy (FESEM) and X-ray Diffraction (XRD). The effects of the parameters of anodic oxidation (such as voltage, the concentration of sulphuric acid, anodization time and current density) on the aperture and the crystalline phase of the TiO2 porous film were systematically investigated. The results indicate that the increase of current density facilitates the augment of the aperture and the generation of anatase and rutile. In addition, the forming mechanism of anatase and rutile TiO2 porous films was discussed.

  1. Cr掺杂金红石相TiO2(110)单晶薄膜的制备、表征及光催化活性%Preparation, Characterization and Photocatalytic Activity of Cr-Doped Rutile TiO2(110) Single Crystal Thin Films

    王阳; 邵翔; 王兵

    2013-01-01

    The growth of Cr-doped rutile TiO2(110) homoepitaxial single crystal thin films using the pulsed laser deposition (PLD) method was investigated.Surface morphology and electronic structure were characterized using scanning tunneling microscopy/spectroscopy (STM/STS),and X-ray and ultraviolet photoemission spectroscopies (XPS/UPS).Optical absorption spectra were measured using ultravioletvisible (UV-Vis) absorption spectroscopy.STM images revealed that the atomically flat TiO2(110)-(1 × 1)surface was maintained at a Cr doping concentration of 6% (atomic ratio),indicating that the Cr dopant had negligible effect on surface morphology.The Cr-doped rutile TiO2(110) film showed higher tunneling conductance than an undoped rutile single crystal.XPS and UPS spectra indicated that Cr atoms bound to lattice O,were present in +3 oxidation state and introduced an impurity state 0.4 eV above the valence band maximum.The UV-Vis absorption spectrum of the Cr-doped film showed an absorbance extending to ~650 nm in the visible range,which was consistent with UPS measurements.Using the Cr-doped TiO2 films,the dissociation of methanol molecules was only observed under irradiation with UV light (wavelength shorter than 430 nm).The dissociation reaction was not observed under irradiation with visible light (wavelength longer than 430 nm).Our results suggest that doping with Cr element alone may not be sufficient to promote the visible light photoactivity of rutile TiO2(110) surfaces.%采用脉冲激光沉积术(PLD)同质外延生长了表面原子级平整的6%(原子比)Cr掺杂的金红石相TiO2(110)单晶薄膜,采用扫描隧道显微镜(STM)、扫描隧道谱(STS)、X射线光电子能谱(XPS)和紫外光电子能谱(UPS)对其进行了表征.结果表明:Cr掺杂对TiO2(110)-(1×1)表面的形貌没有明显影响,但是提高了掺杂薄膜在负偏压的导电性;Cr与晶格O键合而呈现+3价态,由此在TiO2的价带顶上方~0.4 eV处引入杂质能级.紫外-

  2. Photoemission study of TiO2/VO2 interfaces

    Maekawa, K; Takizawa, M.; Wadati, H.; Yoshida, T.; Fujimori, A.; Kumigashira, H.; Oshima, M.; Muraoka, Y.; Nagao, Y.; Hiroi, Z.

    2006-01-01

    We have measured photoemission spectra of two kinds of TiO$_2$-capped VO$_2$ thin films, namely, that with rutile-type TiO$_2$ (r-TiO$_2$/VO$_2$) and that with amorphous TiO$_2$ (a-TiO$_2$/VO$_2$) capping layers. Below the Metal-insulator transition temperature of the VO$_2$ thin films, $\\sim 300$ K, metallic states were not observed for the interfaces with TiO$_2$, in contrast with the interfaces between the band insulator SrTiO$_3$ and the Mott insulator LaTiO$_3$ in spite of the fact that ...

  3. Mesoporous films of TiO2 as efficient photocatalysts for the purification of water

    Rathouský, Jiří; Kalousek, Vít; Kolář, Michal; Jirkovský, Jaromír

    2011-01-01

    Roč. 10, č. 3 (2011), s. 419-424. ISSN 1474-905X R&D Projects: GA ČR GA104/08/0435; GA ČR GD203/08/H032; GA MŠk 1M0577 Institutional research plan: CEZ:AV0Z40400503 Keywords : TiO2 * mesoporous films * photocatalyst Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.584, year: 2011

  4. Comparative study into the photocatalytic performance of mesoporous films of TiO2

    Rathouský, Jiří; Kalousek, Vít

    Praha : VŠCHT Praha, 2010, s. 55-56. ISBN 978-80-7080-750-7. [European Meeting on Solar Chemistry & Photocatalysis: Environmental Applications /6./. Praha (CZ), 13.06.2010-16.06.2010] R&D Projects: GA ČR GA104/08/0435; GA ČR GD203/08/H032 Institutional research plan: CEZ:AV0Z40400503 Keywords : mesoporous films * TiO2 * photocatalysis Subject RIV: CF - Physical ; Theoretical Chemistry

  5. The Effect of Dye Density on the Efficiency of Photosensitization of TiO2 Films: Light-Harvesting by Phenothiazine-Labelled Dendritic Ruthenium Complexes

    Lin-Yong Zhu

    2009-09-01

    Full Text Available A family of dendritic tris-bipyridyl ruthenium coordination complexes incorporating two or four carboxylate groups for binding to a TiO2 surface site and another dendritic linker between the metal complex and highly absorptive dyes were formulated as thin films on TiO2 coated glass. The family included phenothiazine-substituted dendrons of increasing structural complexity and higher optical density. The dye-loaded films were characterized by steady-state emission and absorption measurements and by kinetic studies of luminescence and transient absorption. Upon photoexcitation of the bound dyes, rapid electron injection into the metal oxide film was the dominant observed process, producing oxidized dye that persisted for hundreds of milliseconds. Complex decay profiles for emission, transient absorption, and optical bleaching of the dendritic dyes point to highly heterogeneous behavior for the films, with observed persistence lifetimes related directly to structurally enhance electronic coupling between the metal oxide support and the dendritic dyes.

  6. Superior environment resistance of quartz crystal microbalance with anatase TiO2/ZnO nanorod composite films

    Graphical abstract: ZnO nanorod array being prepared by an in situ method on the QCM coated with Au film via hydrothermal process and surface modification with coated TiO2 by sol–gel methods to form a superhydrophobic TiO2/ZnO composite film the anatase TiO2/ZnO nanorod composite film with a sharp, pencil-like structure exhibiting excellent superhydrophobicity (water contact angle of 155°), non-sticking water properties, and an autonomous cleaning property under UV irradiation. The anatase TiO2/ZnO nanorod composite film facilitates the precise measurement and extended lifetime of the QCM for the detection of organic gas molecules. - Highlights: • This work combines, for the first time, the advantage of the TiO2/ZnO composite film on photocatalysis and reversible super-hydrophobic and super-hydrophilic transition, and puts forward a solution to satisfy weatherability of quartz crystal microbalance in long-term application. • The anatase TiO2/ZnO nanorod composite film with pencil structure exhibit excellent super-hydrophobicity (water contact angle can reach 155°), no-sticking water properties and self-cleaning property under UV irradiation. • The photocatalysis and reversible super-hydrophobic and super-hydrophilic transition of the TiO2/ZnO nanorod composite film is stable in long-term application. - Abstract: The precise measurement of quartz crystal microbalance (QCM) in the detection and weighing of organic gas molecules is achieved due to excellent superhydrophobicity of a deposited film composite. Photocatalysis is utilized as a method for the self-cleaning of organic molecules on the QCM for extended long-term stability in the precision of the instrument. In this paper, ZnO nanorod array is prepared via in situ methods on the QCM coated with Au film via hydrothermal process. Subsequently, a TiO2/ZnO composite film is synthesized by surface modification with TiO2 via sol–gel methods. Results show the anatase TiO2/ZnO nanorod composite film with a

  7. Preparation and Mechanism of Cu-Decorated TiO2-ZrO2 Films Showing Accelerated Bacterial Inactivation.

    Rtimi, Sami; Pulgarin, Cesar; Sanjines, Rosendo; Nadtochenko, Victor; Lavanchy, Jean-Claude; Kiwi, John

    2015-06-17

    Antibacterial robust, uniform TiO2-ZrO2 films on polyester (PES) under low intensity sunlight irradiation made up by equal amounts of TiO2 and ZrO2 exhibited a much higher bacterial inactivation kinetics compared to pure TiO2 or ZrO2. The TiO2-ZrO2 matrix was found to introduce a drastic increase in the Cu-dopant promoter enhancing bacterial inactivation compared to Cu sputtered in the same amount on PES. Furthermore, the bacterial inactivation was accelerated by a factor close to three, by Cu- on TiO2-ZrO2 at extremely low levels ∼0.01%. Evidence is presented by X-ray photoelectron spectroscopy for redox catalysis taking place during bacterial inactivation. The TiO2-ZrO2-Cu band gap is estimated and the film properties were fully characterized. Evidence is provided for the photogenerated radicals intervening in the bacterial inactivation. The photoinduced TiO2-ZrO2-Cu interfacial charge transfer is discussed in term of the electronic band positions of the binary oxide and the Cu TiO2 intragap state. PMID:26023896

  8. Luminescence depolarization effects in protein-modified SiO2-TiO2 films doped with organic luminophores

    Thin SiO2-TiO2 films functionalized with -SH groups were prepared by the sol-gel technique from tetraethoxysilane and (3mercaptopropyl)trimethoxysilane, or -NH2 groups from (3-aminopropyl)-triethoxysilane precursors. Labeled with fluorescein isothiocyanate (FITC), proteins, capable of selective bacterial endotoxins binding, were covalently attached to the films surfaces (via the -NH2 and -SH groups) in a way retaining their rotational freedom. The samples were incubated with selected bacterial endotoxins which bound to the immobilized, FITC-labeled proteins decreasing their rotational freedom. This effect has been detected as a change in the luminescence depolarization. The system based on this effect is proposed as a luminescence biosensor for the endotoxins recognition

  9. Interaction of Sensitizing Dyes with Nanostructured TiO2 Film in Dye-Sensitized Solar Cells Using Terahertz Spectroscopy

    Ghann, William; Rahman, Aunik; Rahman, Anis; Uddin, Jamal

    2016-01-01

    The objective of this investigation was to shed light on the nature of interaction of different organic dyes and an inorganic dye, Ruthenium (II) polypyridine complex, with TiO2 nanoparticles. TiO2 is commonly deployed as an efficient energy transfer electrode in dye sensitized solar cells. The efficiency of dye sensitized solar cells is a function of the interaction of a dye with the electrode material such as TiO2. To the best of our knowledge the present study is the first effort in the determination of terahertz absorbance signals, investigation of real-time dye permeation kinetics, and the surface profiling and 3D imaging of dye sensitized TiO2 films. Herein, we report that the terahertz spectra of the natural dye sensitized TiO2 films were distinctively different from that of the inorganic dye with prominent absorption of natural dyes occurring at approximately the same wavelength. It was observed that the permeation of the natural dyes were more uniform through the layers of the mesoporous TiO2 compared to the inorganic dye. Finally, defects and flaws on TiO2 film were easily recognized via surface profiling and 3D imaging of the films. The findings thus offer a new approach in characterization of dye sensitized solar cells. PMID:27443236

  10. Interaction of Sensitizing Dyes with Nanostructured TiO2 Film in Dye-Sensitized Solar Cells Using Terahertz Spectroscopy.

    Ghann, William; Rahman, Aunik; Rahman, Anis; Uddin, Jamal

    2016-01-01

    The objective of this investigation was to shed light on the nature of interaction of different organic dyes and an inorganic dye, Ruthenium (II) polypyridine complex, with TiO2 nanoparticles. TiO2 is commonly deployed as an efficient energy transfer electrode in dye sensitized solar cells. The efficiency of dye sensitized solar cells is a function of the interaction of a dye with the electrode material such as TiO2. To the best of our knowledge the present study is the first effort in the determination of terahertz absorbance signals, investigation of real-time dye permeation kinetics, and the surface profiling and 3D imaging of dye sensitized TiO2 films. Herein, we report that the terahertz spectra of the natural dye sensitized TiO2 films were distinctively different from that of the inorganic dye with prominent absorption of natural dyes occurring at approximately the same wavelength. It was observed that the permeation of the natural dyes were more uniform through the layers of the mesoporous TiO2 compared to the inorganic dye. Finally, defects and flaws on TiO2 film were easily recognized via surface profiling and 3D imaging of the films. The findings thus offer a new approach in characterization of dye sensitized solar cells. PMID:27443236

  11. Electrochemical deposition of nano-structured ZnO on the nanocrystalline TiO2 film and its characterization

    2010-01-01

    One-dimensional structure of ZnO nanorod arrays on nanocrystalline TiO2/ITO conductive glass substrates has been fabricated by cathodic reduction electrochemical deposition methods in the three-electrode system,with zinc nitrate aqueous solution as the electrolyte,and were characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM),energy-dispersive X-ray (EDX) and photoluminescence (PL) spectra.The effects of film substrates,electrolyte concentration,deposition time,and methenamine (HMT) addition on ZnO deposition and its luminescent property were investigated in detail.The results show that,compared with on the ITO glass substrate,ZnO is much easily achieved by electrochemical deposition on the TiO2 nanoparticle thin films.ZnO is hexagonally structured wurtzite with the c-axis preferred growth,and further forms nanorod arrays vertically on the substrates.It is favorable to the growth of ZnO to extend the deposition time,to increase the electrolyte concentration,and to add a certain amount of HMT in the system,consequently improving the crystallinity and orientation of ZnO arrays.It is demonstrated that the obtained ZnO arrays with high crystallinity and good orientation display strong band-edge UV (375 nm) and weak surface-state-related green (520 nm) emission peaks.

  12. Understanding bactericidal performance on ambient light activated TiO2-InVO4 nanostructured films

    He, Ziming; Xu, Qingchi; Yang Tan, Timothy Thatt

    2011-12-01

    TiO2-InVO4 nanostructured films were coated onto glass substrates and systematically investigated for their bactericidal activities using Escherichia coli (E. coli) as the model bacterium under ambient light illumination. The uniform TiO2-InVO4 nanostructured films were prepared using titanium isopropoxide (TTIP) as the precursor via a simple sol-gel approach. Polyethylenimine (PEI) was used as a surfactant to ensure uniform dispersion of InVO4 and a sacrificial pore-inducing agent, generating nanostructured films. Compared to unmodified TiO2 film, the current TiO2-InVO4 films exhibited enhanced bactericidal activities under ambient light illumination. Bacterial cell ``photo-fixation'' was demonstrated to be crucial in enhancing the bactericidal activity. A bacterial-nanostructured surface interaction mechanism was proposed for the current ambient-light activated nanostructured film.TiO2-InVO4 nanostructured films were coated onto glass substrates and systematically investigated for their bactericidal activities using Escherichia coli (E. coli) as the model bacterium under ambient light illumination. The uniform TiO2-InVO4 nanostructured films were prepared using titanium isopropoxide (TTIP) as the precursor via a simple sol-gel approach. Polyethylenimine (PEI) was used as a surfactant to ensure uniform dispersion of InVO4 and a sacrificial pore-inducing agent, generating nanostructured films. Compared to unmodified TiO2 film, the current TiO2-InVO4 films exhibited enhanced bactericidal activities under ambient light illumination. Bacterial cell ``photo-fixation'' was demonstrated to be crucial in enhancing the bactericidal activity. A bacterial-nanostructured surface interaction mechanism was proposed for the current ambient-light activated nanostructured film. Electronic supplementary information (ESI) available: Photocatalytic activity test procedure and results, AFM images, EDX results, LSCM images, and wettability results. See DOI: 10.1039/c1nr11126d

  13. Photoeletrochemical Properties of TiO2 Films Modified with Gold Nanoparticles

    徐红; 刘玲; 贾能勤; 杨洁; 严曼明; 江志裕

    2005-01-01

    A nano-Au modified TiO2 electrode was prepared via the oxidation of Ti sheet in flame and subsequent modification with gold nanoparticles. The results of SEM and TEM measurements show that the Au nanoparticles are well dispersed on TiO2 surface. A near 2-fold enhancement in photocurrent was achieved upon the modification with Au nanoparticles. From the results of photocurrent and electrochemical impedance experiments it was found that the flatband potential of nano-Au/TiO2 electrode negatively shifted about 100 mV in 0.5 mol/L Na2SO4 solutions compared with that of bare TiO2 electrode. The improvement of photoelectrochemical performance was explained by the inhibition for charge recombination of photo-induced electrons and holes, and the promotion for interracial charge-transfer kinetics at nano-Au/TiO2 composite film. Such nanometal-semiconductor composite films have the potential application in improving the performance of photoelectrochemical solar cells.

  14. Influence of heat treatment temperature on bonding and oxidation resistance of diamond particles coated with TiO2 film

    Xiao-Pan Liu; Dong-Dong Song; Long Wan; Xian-Bing Pang; Zheng Li

    2015-09-01

    In this paper, TiO2 films were coated on the surface of diamond particles using a sol–gel method. The effects of heat treatment temperature on the morphology, composition, chemical bonds, oxidation resistance and compressive strength of diamond particles coated with TiO2 films were characterized through scanning electron microscopy, Fourier transform infrared, Raman spectroscopy, X-ray diffraction analysis, X-ray photoelectron spectroscopy, thermogravimetric–differential scanning calorimetry and compressive strength test. The results showed that when the temperature reached 600°C, the amorphous TiO2 on the diamond particles surface exhibited as a dense anatase film and the Ti–O–C bond formed between TiO2 and the diamond substrates. When temperature reached 800°C, TiO2 films were still in anatase phase and part of the diamond carbon began to graphitize. The graphitizated carbon can also form the Ti–O–C bond with TiO2 film, although TiO2 film would tend to crack in this condition. Meanwhile, the temperature had a serious influence on the oxidation resistance of diamond particles coated with TiO2 films in air. When the heat treatment temperature reached 600°C, the initial oxidation temperature of the coated diamond particles reached the maximum value of 754°C. When the diamond particles were oxidized at 800°C for 0.5 h in air, the weight loss rate reached the minimum value of 6.7 wt% and the compressive strength reached the maximum value of 15.7 N.

  15. Effects of electron beam irradiation on the photoelectrochemical properties of TiO2 film for DSSCs

    ABSTRACT: TiO2 has been widely utilized for various industrial applications such as photochemical cells, photocatalysts, and electrochromic devices. The crystallinity and morphology of TiO2 films play a significant role in determining the overall efficiency of dye-sensitized solar cells (DSSCs). In this study, the preparation of nanostructured TiO2 films by electron beam irradiation and their characterization were investigated for the application of DSSCs. TiO2 films were exposed to 20–100 kGy of electron beam irradiation using 1.14 MeV energy acceleration with a 7.46 mA beam current and 10 kGy/pass dose rates. These samples were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and X-ray photoelectron spectroscopy (XPS) analysis. After irradiation, each TiO2 film was tested as a DSSC. At low doses of electron beam irradiation (20 kGy), the energy conversion efficiency of the film was approximately 4.0% under illumination of simulated sunlight with AM 1.5 G (100 mW/cm2). We found that electron beam irradiation resulted in surface modification of the TiO2 films, which could explain the observed increase in the conversion efficiency in irradiated versus non-irradiated films. - Highlights: ► The surface of TiO2 particles was modified by electron beam irradiation. ► The aggregation between each TiO2 particle was observed in the SEM images. ► Ti3+ state was enhanced due to the excess electron injection via electron beam irradiation. ► The power conversion efficiency of DSSCs was enhanced.

  16. Preparation of porous nanocrystalline TiO2 electrode by screen-printing technique

    XIE DongMei; FENG ShuJing; LIN Yuan; DONG GuoJun; XIAO XuRui; LI XuePing; ZHOU XiaoWen

    2007-01-01

    Different paste has been used for preparing porous TiO2 thin film by screen-printing technique, the main component of it comes from commercial TiO2 P25 power. The dye-sensitized solar cell based on this TiO2 thin film without further chemical treatments exhibits high overall conversion efficiency of 5.81%―6.70%, even with low TiO2 content and thin film thickness. The experimental repeatability is nice and the properties of the films are uniform.

  17. Influence of catalyst on structural and morphological properties of TiO2 nanostructured films prepared by sol-gel on glass

    Mehdi Alzamani; Ali Shokuhfar; Ebrahim Eghdam; Sadegh Mastali

    2013-01-01

    Transparent TiO2 thin films have been prepared by the sol-gel method using titanium alkoxides as precursors. Thin films were deposited on glass supports by the dip-coating technique. The TiO2 layer acts as a self-cleaning coating generated from its photocatalysis and photoinduced superhydrophilicity. The crystalline structure of TiO2 films was dominantly identified as the anatase phase, consisted of uniform spherical particles of about 14-50 nm in size, which strongly depends upon catalyst-type and heat treatment temperature. Increasing heat treating temperature can lead to an increase in crystalline size. The results indicated that the sample S.S (sample derived from sol containing sulfuric acid as catalyst) exhibits superhydrophilic nature and better photocatalytic activity, which can be attributed to its higher anatase content and lower crystalline size. Morphological studies, carried out using Atomic Force Microscopy (AFM), confirm the presence of crystalline phase with such a grain size and low surface roughness. Thus, the applied films exhibiting high photocatalytic activity, superhydrophilic behavior, and low surface roughness can be used as an efficient self-cleaning coating on glass and other optical applications.

  18. Formaldehyde gas sensor based on TiO2 thin membrane integrated with nano silicon structure

    Zheng, Xuan; Ming, An-jie; Ye, Li; Chen, Feng-hua; Sun, Xi-long; Liu, Wei-bing; Li, Chao-bo; Ou, Wen; Wang, Wei-bing; Chen, Da-peng

    2016-07-01

    An innovative formaldehyde gas sensor based on thin membrane type metal oxide of TiO2 layer was designed and fabricated. This sensor under ultraviolet (UV) light emitting diode (LED) illumination exhibits a higher response to formaldehyde than that without UV illumination at low temperature. The sensitivities of the sensor under steady working condition were calculated for different gas concentrations. The sensitivity to formaldehyde of 7.14 mg/m3 is about 15.91 under UV illumination with response time of 580 s and recovery time of 500 s. The device was fabricated through micro-electro-mechanical system (MEMS) processing technology. First, plasma immersion ion implantation (PIII) was adopted to form black polysilicon, then a nanoscale TiO2 membrane with thickness of 53 nm was deposited by DC reactive magnetron sputtering to obtain the sensing layer. By such fabrication approaches, the nanoscale polysilicon presents continuous rough surface with thickness of 50 nm, which could improve the porosity of the sensing membrane. The fabrication process can be mass-produced for the MEMS process compatibility.

  19. Synthesis of V, Er and Ce Substitued TiO2 Films via Sol-gel Method to Degrade Cynanide Content in Waste Water Under UV/Sunlight Source

    ÇAKIROĞLU, Erkan; Mustafa EROL; KOCAKUŞ, Sibel; ÇELİK, Erdal

    2014-01-01

    In this study, Vanadium (V), Erbium (Er) and Cerium (Ce) substituted TiO2 films were deposited on glass substrates via sol-gel technique in industrial scale in order to provide photocatalytic degradation of cyanide in waste water. Structural, microstructural and electrical properties of the thin films were examined and thin films coated on glass substrates were used as the photocatalyzer in the photocatalytic degradation of cyanide in waste waters under UV/sunlight source. It was found that 8...

  20. Effects of electron beam irradiation on the photoelectrochemical properties of TiO2 film for DSSCs

    Kim, Hyun-Bin; Park, Dong-Won; Jeun, Joon-Pyo; Oh, Seung-Hwan; Nho, Young-Chang; Kang, Phil-Hyun

    2012-08-01

    iO2 has been widely utilized for various industrial applications such as photochemical cells, photocatalysts, and electrochromic devices. The crystallinity and morphology of TiO2 films play a significant role in determining the overall efficiency of dye-sensitized solar cells (DSSCs). In this study, the preparation of nanostructured TiO2 films by electron beam irradiation and their characterization were investigated for the application of DSSCs. TiO2 films were exposed to 20-100 kGy of electron beam irradiation using 1.14 MeV energy acceleration with a 7.46 mA beam current and 10 kGy/pass dose rates. These samples were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and X-ray photoelectron spectroscopy (XPS) analysis. After irradiation, each TiO2 film was tested as a DSSC. At low doses of electron beam irradiation (20 kGy), the energy conversion efficiency of the film was approximately 4.0% under illumination of simulated sunlight with AM 1.5 G (100 mW/cm2). We found that electron beam irradiation resulted in surface modification of the TiO2 films, which could explain the observed increase in the conversion efficiency in irradiated versus non-irradiated films.

  1. Intrinsic defects and their influence on the chemical and optical properties of TiO2-x films

    In this work, TiO2 films produced by rf sputtering of a TiO2 target in argon and argon-oxygen plasmas were studied. The oxygen content in the feed gas was varied in a range 3-20%. The chemical composition and structure of films were characterized by Rutherford backscattering spectrometry, x-ray photoelectron spectroscopy (XPS) and x-ray diffraction. Important information about the intrinsic defects of the films and their effects on the optical properties as well as a scheme of the energy band structure of the films could be derived from a combined use of optical spectroscopy and XPS.

  2. Unsymmetrical extended -conjugated zinc phthalocyanine for sensitization of nanocrystalline TiO2 films

    L Giribabu; Ch Vijay Kumar; P Yella Reddy; Jun-Ho Yum; M Grätzel; Md K Nazeeruddin

    2009-01-01

    We have designed and synthesized a new unsymmetrical zinc phthalocyanine based on `push-pull’ and extended -conjugation concept, PCH008. The new sensitizer was fully characterized by CHN anlysis, UV-Vis., fluorescence spectroscopies and cyclic voltammetry. The new sensitizer which upon anchoring onto nanocrystalline TiO2 film exhibit a short circuit current of 5.63 mA cm-2, open circuit potential of 557.0 mV and a fill factor of 0.75 corresponding to an overall conversion efficiency of 2.35% under standard global air mass (AM) 1.5 solar conditions and compared its performance with literature reported phthalocyanine dyes.

  3. The Photocatalytic Property of Nitrogen-Doped TiO2 Nanoball Film

    Haiying Wang

    2013-01-01

    Full Text Available TiO2 nanoball films of nitrogen doping and no doping were prepared by anodic oxidation method. The nitrogen-doped samples exhibited significant enhanced absorption in visible light range, narrowing band gap from 3.2 eV to 2.8 eV and the smaller nanoball diameter size. The concentrations of methyl blue reduce to nearly 44% after 4-hour photodecomposition test by nitrogen-doped sample. It is indicated that there may be two main reasons for the enhanced photocatalytic activity: the increase of O vacancy and photocatalytic reactivity surface area in nitrogen-doped samples.

  4. Solvent Effect on the Electrical and Optical Properties of Nano composite MEH-PPV: TiO2 Films for Organic Solar Cells Applications

    The influence of organic solvent on the electrical and optical properties of photodiodes based on poly[2-methoxy,5-(2'- ethylhexyloxy)-1,4-phenylene vinylene) MEHPPV) and nano-TiO2 nano composite are investigated. The films were prepared from TiO2 dispersed in MEH-PPV solutions in toluene, tetrahydrofuran (THF), xylene, chloroform and 1,3-dichlorobenzene (1,3- DCB) solvents at concentration of 20 mg/ 20 ml. The electrical properties of the MEH-PPV: TiO2 nano composite thin films were measured by solar simulator in dark and under illumination condition while the characterization of optical properties has using UV-VIS spectrophotometer to evaluate the absorbance. The solvent of 1,3-DCB shows a greater conductivity with 33.82x104 S.m-1 without photo response under illumination. (author)

  5. Enhancement of photoelectrochemical activity of SnS thin-film photoelectrodes using TiO2, Nb2O5, and Ta2O5 metal oxide layers

    Vequizo, Junie Jhon M.; Yokoyama, Masanori; Ichimura, Masaya; Yamakata, Akira

    2016-06-01

    Tin sulfide (SnS) fine photoelectrodes fabricated by three-step pulsed electrodeposition were active for H2 evolution. The incident-photon-conversion-efficiency increases from 900 nm and offers a good fit with the absorption spectrum. The activity was enhanced by 3.4, 3.0, and 1.8 times compared to bare SnS by loading Nb2O5, TiO2, and Ta2O5, respectively. Nb2O5 was most efficient because its conduction band is low enough to facilitate effective electron transfer from SnS; it also has sufficiently high potential for H2 evolution. The overall activity is determined by the competitive interfacial electron transfer between SnS/metal-oxide and metal-oxide/water. Therefore, constructing appropriate heterojunctions is necessary for further improving photoelectrochemical systems.

  6. Electrodeposited ZnO thin film as an efficient alternative blocking layer for TiCl4 pre-treatment in TiO2-based dye sensitized solar cells

    Kouhestanian, E.; Mozaffari, S. A.; Ranjbar, M.; SalarAmoli, H.; Armanmehr, M. H.

    2016-08-01

    Recently, ZnO nanostructures have received considerable attention in fabrication of dye sensitized solar cell (DSSC) photoanodes due to their unique transport properties. In the present study, a chronoamperometric method was performed to fabricate the ZnO nanostructures as an appropriate alternative of TiCl4 pre-treatment to reduce the recombination reactions, while retaining the TiO2-based DSSC performance. The effect of polyvinyl alcohol (PVA) on ZnO electrodeposition to control the growth and crystallization of ZnO nanostructures was investigated. ZnO/TiO2 based-DSSCs were fabricated using N719 ruthenium dye and all photovoltaic parameters were characterized. Incident photon to current efficiency (IPCE), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and VOC decay techniques were employed for studying the cell properties which is resulted in a significant enhancement in cell performance.

  7. Thin films

    This volume is a compilation of papers presented at the 1990 Spring Meeting of the Materials Research Society in a symposium entitled Thin Films: Stresses and Mechanical Properties II. As indicated by the title, the symposium was the second in a series, the first of which was held at the Fall Meeting in 1988. The importance of thin film mechanical properties is now recognized to the extent that basic characterization techniques such as microindentation and thin film stress measurement are performed routinely, and new characterization techniques are being developed on a daily basis. Many of the papers in the symposium dealt with the developments in these characterization methods and their application to a broad spectrum of materials such as compositionally modulated structures, ion implanted materials, optical coatings, and the numerous metals, ceramics and organics used in semiconductor device manufacture

  8. Influences of annealing temperature on microstructure and properties for TiO2 films deposited by DC magnetron sputtering

    Shang, Jie-Ting; Chen, Chih-Ming; Cheng, Ta-Chih; Lee, Ying-Chieh

    2015-12-01

    Titanium dioxide films were deposited at 100 °C of substrate temperature with a DC magnetron sputtering system. The crystalline structures, morphological features, and photocatalytic activity of the TiO2 films were systematically studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and ultraviolet spectrophotometry. To obtain the crystalline structure of TiO2 film at a low annealing temperature, high-level DC power (600 W) was applied. The effect of the annealing treatments on the microstructure of the TiO2 films was investigated. The results indicated that the annealing process at 200 °C clearly caused the formation of a nanocrystalline anatase phase that directly affected photocatalytic activity. The dye removal efficiency of the nanostructured anatase attained 53 and 31% for UV and visible light radiation, respectively.

  9. (I2)n-encapsulated and C-encapsulated TiO2 films: Enhanced photoelectrochemical and visible-light photoelectrocatalytic properties

    Highlights: ► (I2)n-encapsulated TiO2 (I2-TiO2) and C-encapsulated TiO2 (C-TiO2) film electrodes were prepared. ► I2-TiO2 and C-TiO2 films show improved light absorbance in 400–550 nm. ► Lower electron transfer resistance and more negative flat band potentials were obtained from them. ► The photoelectrocatalytic activities of I2-TiO2 and C-TiO2 films were much higher than TiO2 film. - Abstract: Visible-light absorbing (I2)n-encapsulated TiO2 film (I2-TiO2 film) and C-encapsulated TiO2 film (C-TiO2 film) were fabricated and studied as film electrodes for their photoelectrochemical and photoelectrocatalytic (PEC) properties. The as-prepared film electrodes were characterized by scanning electronic microscopy, energy-dispersive X-ray spectroscopy and UV–visible diffuse reflectance spectroscopy. The photoelectrochemical properties were evaluated by the incident photo-to-current conversion efficiency, electrochemical impedance spectroscopy and Mott–Schottky analysis data. The results showed that I2-TiO2 and C-TiO2 films exhibited stronger absorption in the 400–550 nm range, lower electron transfer resistance and more negative flat band potentials comparing with pure TiO2 film. Moreover, the photoelectrochemical ability of I2-TiO2 film is superior to that of C-TiO2 film. At a bias potential of 0.5 vs (Ag/AgCl)/V, the visible-light-induced PEC degradation ratios of rhodamine B and tetracycline on I2-TiO2 film or C-TiO2 film electrodes exceeded that on pure TiO2 electrode, with the improvement by a factor of about 5 or 3. The higher PEC activity of I2-TiO2 film and C-TiO2 film could be attributed to the enhancement of separation of electron-hole pair at the external electric field and the extension of the light response range of TiO2 to the visible light with a red shift in the band gap transition.

  10. Intrinsic defects and their influence on the chemical and optical properties of TiO2x films

    Laidani, N.; Cheyssac, P; Perrière, J; Bartali, R.; Gottardi, G.; Luciu, I; Micheli, V

    2010-01-01

    ABSTRACT In this work, TiO 2 films produced by rf sputtering of a TiO 2 target, in argon and argon-oxygen plasmas were studied. The oxygen content in the feed gas was varied in a range of 3% ? 20%. The chemical composition and structure of films were characterized by Rutherford backscattering spectrometry (RBS), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction. Important information about the intrinsic defects of the films and their effects on the optical properties as well as ...

  11. Consequences of niobium doping for the ferromagnetism and microstructure of anatase Co: TiO2 films

    Zhang, S. X.; Ogale, S.B.; Fu, L. F.; Dhar, S.; Kundaliya, D. C.; Ramadan, W.; Browning, N. D.; Venkatesan, T.

    2006-01-01

    It is shown that dilute niobium doping has significant effect on the ferromagnetism and microstructure of dilutely cobalt-doped anatase TiO2 films. Epitaxial films of anatase TiO2 with 3% Co, without and with 1% niobium doping were grown by pulsed-laser deposition at 875 C at different oxygen pressures. For growth at 10^{-5} Torr niobium doping suppresses the ferromagnetism, while it enhances the same in films grown at 10^{-4} Torr. High-resolution Z-contrast Scanning Transmission Electron Mi...

  12. Dye-Sensitized Solar Cells with Anatase TiO2 Nanorods Prepared by Hydrothermal Method

    Ming-Jer Jeng

    2013-01-01

    Full Text Available The hydrothermal method provides an effective reaction environment for the synthesis of nanocrystalline materials with high purity and well-controlled crystallinity. In this work, we started with various sizes of commercial TiO2 powders and used the hydrothermal method to prepare TiO2 thin films. We found that the synthesized TiO2 nanorods were thin and long when smaller TiO2 particles were used, while larger TiO2 particles produced thicker and shorter nanorods. We also found that TiO2 films prepared by TiO2 nanorods exhibited larger surface roughness than those prepared by the commercial TiO2 particles. It was found that a pure anatase phase of TiO2 nanorods can be obtained from the hydrothermal method. The dye-sensitized solar cells fabricated with TiO2 nanorods exhibited a higher solar efficiency than those fabricated with commercial TiO2 nanoparticles directly. Further, triple-layer structures of TiO2 thin films with different particle sizes were investigated to improve the solar efficiency.

  13. Dip-coated TiO2CeO2 films as transparent counter-electrode for transmissive electrochromic devices

    Baudry, Paul; Rodrigues, A. C. M.; Michel A. Aegerter; Bulhoes, Luis O. S.

    1990-01-01

    The dip-coating process is an attractive way for the preparation of thin films used in the field of electrochromism. The scope of the present paper is focused on the TiO2CeO2 compounds since they exhibit a reversible electrochemical insertion of lithium ions maintaining a high optical transmissivity. These films can be used as transparent counter-electrode in an all solid state electrochromic transmissive device with, for example, WO3 as electrochromic material and a lithium conductive po...

  14. Properties of Ultrathin Al2O3-TiO2 Nanolaminate Films for Gate Dielectric Applications Deposited by Plasma-Assisted Atomic Layer Deposition

    Garces, Nelson; Meyer, David; Nepal, Neeraj; Wheeler, Virginia; Eddy, Charles

    2012-02-01

    High permittivity dielectrics such as Al2O3, HfO2, Ta2O5, TiO2, etc., are an essential component of aggressively-scaled III-V and graphene field effect transistors (FETs) where insulators are necessary to reduce gate leakage current while maintaining high gate capacitance and charge control of the channel. Atomic layer deposition (ALD) has the capability to deposit hybrid films, or nanolaminates, of two or more dielectrics that have unique properties. Thin [Al2O3+TiO2] nanolaminates with varying TiO2 and Al2O3 content were deposited on n-Si substrates at ˜225-300 C using ALD. A nanolaminate is composed of bilayers, defined as the sum of (x)Al2O3 and (y)TiO2, where x, and y indicate the number of times a component monolayer is repeated. While the overall thickness of the dielectric was held at ˜ 17-20 nm, the relative ratio of Al2O3 to TiO2 in the bilayer stack was varied to evaluate changes in the material properties and electrical performance of the oxides. C-V and I-V measurements on various [(x)TiO2+(y)Al2O3] MOS capacitors were taken. The high-TiO2-content films show limited evidence of oxide charge trapping and relatively large dielectric constants (κ˜15), whereas the high-Al2O3-content films offer a larger optical bandgap and improved suppression of leakage current. We will discuss the properties of very thin nanolaminates and their possible use as gate oxides. Morphological, electrical, and XPS composition assessments will be presented.

  15. Thin Films

    Šolcová, Olga

    Maribor: Univerza v Mariboru, 2013. [Nanofuture. Maribor (SI), 03.02.2013-07.02.2013] R&D Projects: GA TA ČR TA01020804 Institutional support: RVO:67985858 Keywords : sol-gel methods * thin films * nannomaterials Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  16. Uniform deposition of ternary chalcogenide nanoparticles onto mesoporous TiO2 film using liquid carbon dioxide-based coating

    We report the simultaneous deposition of two different metal precursors dissolved in liquid carbon dioxide (l-CO2), aiming to the synthesis of ternary chalcopyrite (e.g. CuInS2) nanoparticles on a mesoporous TiO2 film. The l-CO2-based deposition of Cu and In precursors and subsequent reaction with a dilute H2S gas resulted in CuxInySz nanoparticles uniformly deposited across the entire thickness of a mesoporous TiO2 film. Further heat treatment (air annealing and sulfurization) led to the formation of more stoichiometric CuInS2 nanoparticles. The formation of CuInS2 on TiO2 was confirmed by scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction, and Raman spectroscopy. The crystal growth of CuInS2 was also found to be controllable by adjusting the number of coating cycles of the l-CO2-based deposition. - Highlights: • Simultaneous deposition of two different metal precursors dissolved in l-CO2. • Uniform deposition of CuInS2 nanoparticles across mesoporous TiO2 film. • Highly crystalline CuInS2 formed on mesoporous TiO2 film. • Nearly stoichiometric ratio of Cu:In:S was obtained

  17. Passivation of pigment-grade TiO2 particles by nanothick atomic layer deposited SiO2 films

    Pigment-grade TiO2 particles were passivated using nanothick insulating films fabricated by atomic layer deposition (ALD). Conformal SiO2 and Al2O3 layers were coated onto anatase and rutile powders in a fluidized bed reactor. SiO2 films were deposited using tris-dimethylaminosilane (TDMAS) and H2O2 at 500 deg. C. Trimethylaluminum and water were used as precursors for Al2O3 ALD at 177 deg. C. The photocatalytic activity of anatase pigment-grade TiO2 was decreased by 98% after the deposition of 2 nm SiO2 films. H2SO4 digest tests were performed to exhibit the pinhole-free nature of the coatings and the TiO2 digest rate was 40 times faster for uncoated TiO2 than SiO2 coated over a 24 h period. Mass spectrometry was used to monitor reaction progress and allowed for dosing time optimization. These results demonstrate that the TDMAS-H2O2 chemistry can deposit high quality, fully dense SiO2 films on high radius of curvature substrates. Particle ALD is a viable passivation method for pigment-grade TiO2 particles

  18. Nitrogen-doped TiO2 nanotube array films with enhanced photocatalytic activity under various light sources

    Highly ordered nitrogen-doped titanium dioxide (N-doped TiO2) nanotube array films with enhanced photocatalytic activity were fabricated by electrochemical anodization, followed by a wet immersion and annealing post-treatment. The morphology, structure and compostition of the N-doped TiO2 nanotube array films were investigated by FESEM, XPS, UV-vis and XRD. The effect of annealing temperature on the morphology, structures, photoelectrochemical property and photo-absorption of the N-doped TiO2 nanotube array films was investigated. Liquid chromatography and mass spectrometry were applied to the analysis of the intermediates coming from the photocatalytic degradation of MO. The experimental results showed that there were four primary intermediates existing in the photocatalytic reaction. Compared with the pure TiO2 nanotube array film, the N-doped TiO2 nanotubes exhibited higher photocatalytic activity in degradating methyl orange into non-toxic inorganic products under both UV and simulated sunlight irradiation.

  19. Enhanced near infrared reflectance of TiO2/SiO2/TiO2 multilayer structure using a base-catalyzed SiO2 film

    Near infrared (NIR) reflective TiO2 (high)/SiO2 (low)/TiO2 (high) multilayer film is fabricated by sol–gel synthesis and spin coating process. This multilayer film is used to reflect the NIR waves which can undesirably increase indoor energy of buildings while the visible waves are being transmitted. It is advantageous for high reflectance with higher value of the refractive index for the high component and lower value of the refractive index for the low component. Acid- or base-catalyzed SiO2 film has a distinctive refractive index due to the different porous structure of the films. The base-catalyzed SiO2 film shows much lower refractive index than the acid-catalyzed SiO2 film, and thus the TiO2/SiO2/TiO2 multilayer structure with the base-catalyzed SiO2 film has higher NIR reflectance than the acid-catalyzed SiO2 case. Experimentally measured reflectance for the multilayer structure is compared with the transfer matrix calculation, and the experimental results show good agreements with the model calculations. Therefore, higher NIR reflectance of TiO2/SiO2/TiO2 multilayer structure can be achieved by incorporating lower refractive index SiO2 film. - Highlights: • TiO2/SiO2/TiO2 multilayer structure fabricated by sol–gel process and spin coating • Formation of the porous structure of the base-catalyzed SiO2 film • Low refractive index value of the SiO2 film using the base-catalyst • Improved NIR reflectance from the multilayer with the base-catalyzed SiO2 film

  20. Memory programming of TiO2−x films by Conductive Atomic Force Microscopy evidencing filamentary resistive switching

    Highlights: • We correlate RRAM performance with C-AFM measurements. • We demonstrate resistive switching through C-AFM process. • We present evidence of filament formation. • We demonstrate resistive switching in nanoscale area. - Abstract: Resistive Random Access Memory (RRAM) with a structure Au/Ti/TiO2−x/Au demonstrated a clear bipolar resistive switching behavior without the necessity of an initial electroforming process. The titanium oxide (TiO2−x) thin film was deposited by reactive RF magnetron sputtering at room temperature in a controlled oxygen/argon ambient. The high density of oxygen vacancies within the film (induced by the low oxygen content) is an essential component for the formation of conducting filaments and demonstration of DC or nanosecond pulsed resistance switching, but also impose limitations for the conduction behavior of the high resistance state. Conductive Atomic Force Microscopy (C-AFM) was then employed in order to investigate the nanoscale electrical properties of our device. In situ current distribution during the SET process disclosed possible formation of conducting filaments while DC sweeping bias voltage revealed an OFF/ON switching ratio of about 200. We have also demonstrated that by using C-AFM both a low resistance state and a high resistance state can be written by bipolar voltage application imaged by corresponding patterns on the TiO2−x current image, suggesting that oxygen ions movement at the Pt-Ir coated tip/TiO2−x interface plays a critical role in the resistive switching phenomenon and thus correlating the macroscopic characteristics of our device with its microscopic origins. Nanoscale resistance switching is also demonstrated by programming distinct patterns on the device's current image

  1. Self-assembly and photoelectric properties of cerium complexes with 3,4,9,10-perylenetetracarboxylic acid on nanocrystalline TiO2 films

    王忠胜; 黄春辉; 李富友; 杨术明; 翁诗甫; 付小艺; 吴念祖; 奎热西; 刘凤琴; 钱海杰

    2001-01-01

    Self-assembled (SA) films (PMP, M = Ce3+ or Ce4+) of 3,4,9,10-perylenetetracarboxylic acid (PTA) on nanocrystalline TiO2 films with Ce3+ or Ce4+ as a bridge were fabricated and characterized with UV-Vis, IR, and XPS synchrotron radiation photoelectron spectroscopy (SRPES) which gave the HOMO energy levels for the SA films. It was shown that thin-layer sandwich-type solar cells based on these SA films possess good properties for photoelectric conversion. While PTA-loaded TiO2 electrode (P) generated 26.9% of incident monochromatic photon-to-electron conversion efficiency (IPCE), PMP-sensitized Ti02 electrodes yielded 55.8% and 39.1% for Ce4+ and Ce3+ respectively. PMP films can be considered as a kind of complexes whose HOMO energy levels were proved to be higher than that of film P, which is one of the major reasons for the increase in IPCE from film P to film PMP.

  2. Fabrication of CoTiO3-TiO2 composite films from a heterobimetallic single source precursor for electrochemical sensing of dopamine.

    Ehsan, Muhammad Ali; Naeem, Rabia; Khaledi, Hamid; Sohail, Manzar; Hakeem Saeed, Abbas; Mazhar, Muhammad

    2016-06-21

    Cobalt titanate-titania composite oxide films have been grown on FTO-coated glass substrates using a single-source heterometallic complex [Co2Ti4(μ-O)6(TFA)8(THF)6]·THF () which was obtained in quantitative yield from the reaction of diacetatocobalt(ii) tetrahydrate, tetraisopropoxytitanium(iv), and trifluoroacetic acid from a tetrahydrofuran solution. Physicochemical investigations of complex have been carried out by melting point, FT-IR, thermogravimetric and single-crystal X-ray diffraction analyses. CoTiO3-TiO2 films composed of spherical objects of various sizes have been grown from by aerosol-assisted chemical vapor deposition at different temperatures of 500, 550 and 600 °C. Thin films characterized by XRD, Raman and X-ray photoelectron spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis have been explored for electrochemical detection of dopamine (DA). The cyclic voltammetry with the CoTiO3-TiO2 electrode showed a DA oxidation peak at +0.215 V while linear sweep voltammetry displayed a detection limit (LoD) of 0.083 μM and a linear concentration range of 20-300 μM for DA. Thus, the CoTiO3-TiO2 electrode is a potential candidate for the sensitive and selective detection of DA. PMID:27230711

  3. Low Temperature Coating of Anatase Thin Films on Silica Glass Fibers by Liquid Phase Deposition

    LI Shun; LIU Jiachen; FENG Tiecheng

    2007-01-01

    Uniform crystalline TiO2 thin films were coated on silica glass fibers by liquid phase deposition from aqueous solution of ammonium hexafluorotitanate at low temperature. TiO2 thin films and nanopowders were prepared by adding H3BO3 into (NH4)2TiF6 solution supersaturated with anatase nano-crystalline TiO2 at 40 ℃. The effects of the deposition conditions on the surface morphology, section morphology, thickness of the deposited TiO2 thin films were investigated. The results indicate that the growth rate and particle size of the thin films were controlled by both the deposition conditions and the amount of anatase nano-crystalline TiO2.

  4. Relationships among growth mechanism, structure and morphology of PEALD TiO2 films: the influence of O2 plasma power, precursor chemistry and plasma exposure mode.

    Chiappim, W; Testoni, G E; Doria, A C O C; Pessoa, R S; Fraga, M A; Galvão, N K A M; Grigorov, K G; Vieira, L; Maciel, H S

    2016-07-29

    Titanium dioxide (TiO2) thin films have generated considerable interest over recent years, because they are functional materials suitable for a wide range of applications. The efficient use of the outstanding functional properties of these films relies strongly on their basic characteristics, such as structure and morphology, which are affected by deposition parameters. Here, we report on the influence of plasma power and precursor chemistry on the growth kinetics, structure and morphology of TiO2 thin films grown on Si(100) by plasma-enhanced atomic layer deposition (PEALD). For this, remote capacitively coupled 13.56 MHz oxygen plasma was used to act as a co-reactant during the ALD process using two different metal precursors: titanium tetrachloride (TiCl4) and titanium tetraisopropoxide (TTIP). Furthermore, we investigate the effect of direct plasma exposure during the co-reactant pulse on the aforementioned material properties. The extensive characterization of TiO2 films using Rutherford backscattering spectroscopy, ellipsometry, x-ray diffraction (XRD), field-emission scanning electron microscopy, and atomic force microscopy (AFM) have revealed how the investigated process parameters affect their growth per cycle (GPC), crystallization and morphology. The GPC tends to increase with plasma power for both precursors, however, for the TTIP precursor, it starts decreasing when the plasma power is greater than 100 W. From XRD analysis, we found a good correlation between film crystallinity and GPC behavior, mainly for the TTIP process. The AFM images indicated the formation of films with grain size higher than film thickness (grain size/film thickness ratio ≈20) for both precursors, and plasma power analysis allows us to infer that this phenomenon can be directly related to the increase of the flux of energetic oxygen species on the substrate/growing film surface. Finally, the effect of direct plasma exposure on film structure and morphology was evidenced

  5. Relationships among growth mechanism, structure and morphology of PEALD TiO2 films: the influence of O2 plasma power, precursor chemistry and plasma exposure mode

    Chiappim, W.; Testoni, G. E.; Doria, A. C. O. C.; Pessoa, R. S.; Fraga, M. A.; Galvão, N. K. A. M.; Grigorov, K. G.; Vieira, L.; Maciel, H. S.

    2016-07-01

    Titanium dioxide (TiO2) thin films have generated considerable interest over recent years, because they are functional materials suitable for a wide range of applications. The efficient use of the outstanding functional properties of these films relies strongly on their basic characteristics, such as structure and morphology, which are affected by deposition parameters. Here, we report on the influence of plasma power and precursor chemistry on the growth kinetics, structure and morphology of TiO2 thin films grown on Si(100) by plasma-enhanced atomic layer deposition (PEALD). For this, remote capacitively coupled 13.56 MHz oxygen plasma was used to act as a co-reactant during the ALD process using two different metal precursors: titanium tetrachloride (TiCl4) and titanium tetraisopropoxide (TTIP). Furthermore, we investigate the effect of direct plasma exposure during the co-reactant pulse on the aforementioned material properties. The extensive characterization of TiO2 films using Rutherford backscattering spectroscopy, ellipsometry, x-ray diffraction (XRD), field-emission scanning electron microscopy, and atomic force microscopy (AFM) have revealed how the investigated process parameters affect their growth per cycle (GPC), crystallization and morphology. The GPC tends to increase with plasma power for both precursors, however, for the TTIP precursor, it starts decreasing when the plasma power is greater than 100 W. From XRD analysis, we found a good correlation between film crystallinity and GPC behavior, mainly for the TTIP process. The AFM images indicated the formation of films with grain size higher than film thickness (grain size/film thickness ratio ≈20) for both precursors, and plasma power analysis allows us to infer that this phenomenon can be directly related to the increase of the flux of energetic oxygen species on the substrate/growing film surface. Finally, the effect of direct plasma exposure on film structure and morphology was evidenced

  6. High-Quality Fe-doped TiO2 films with Superior Visible-Light Performance

    Su, Ren; Bechstein, Ralf; Kibsgaard, Jakob;

    2012-01-01

    We report on high-quality polycrystalline Fe-doped TiO2 (Fe–TiO2) porous films synthesized via one-step electrochemical oxidation. We demonstrate that delicate properties such as the impurity concentration and the microstructure that strongly influence the performance of the material for photovol......We report on high-quality polycrystalline Fe-doped TiO2 (Fe–TiO2) porous films synthesized via one-step electrochemical oxidation. We demonstrate that delicate properties such as the impurity concentration and the microstructure that strongly influence the performance of the material...

  7. GROWTH, SURFACE CHARACTERIZATION, AND REACTIVITY OF TIO2 ANATASE FILMS-EPSCOR

    Diebold, Ulrike

    2004-12-15

    TiO2 is as promising photocatalyst for environmental degradation of organic compounds and solar energy conversion. Commercial titania is a mixture of rutile and anatase phases, and, for as of yet unknown reasons, anatase is the photocatalytically more active form. In contrast to rutile, atomic-scale information on well-characterized anatase surfaces and their chemical properties was virtually absent at the beginning of this project. We have performed surface science investigations of anatase with the goal to understand, and ultimately control, the surface chemistry underlying its diverse applications. We have of (1) characterized all main crystallographic surface orientations of anatase, namely the (101), (100), (001), and (103) surfaces (2) have investigated the influence of surface imperfections such as defects and steps; (3) have investigated the influence of dopants on epitaxial (001) anatase films; and (3) have investigated the chemical and adsorption and reaction processes of simple molecules (water and methanol) on anatase surfaces. The experiments were performed in collaboration with Pacific Northwest National Laboratory (PNNL) using a variety of complementary surface science techniques. They have lead to a thorough characterization of this model system and have provided a more complete understanding of TiO2, which could possibly lead to improved efficiency in of photocatalytic applications.

  8. Influence of the heating temperature on the properties of nickel doped TiO2 films prepared by sol-gel method

    Formation and properties of nickel doped TiO2 films prepared by sol-gel method were studied using X-ray photoelectron spectroscopy, X-ray diffraction, atomic force microscopy, and energy dispersive X-ray analysis. The results demonstrate that sizes of TiO2 crystallites increase with increasing heating temperature. Also, at temperatures above 800 o C diffusion of nickel onto the surfaces results in increased concentrations of nickel compounds on the surfaces. Similar to pure TiO2 films the light-induced modification of hydrophilicity is observed also in the case of nickel doped TiO2 films.

  9. Bolometric properties of reactively sputtered TiO2−x films for thermal infrared image sensors

    A heat-sensitive layer (TiO2−x) was successfully deposited by RF reactive magnetron sputtering for infrared (IR) image sensors at different relative mass flow of oxygen gas (R O2) levels. The deposition rate was decreased with an increase in the percentage of R O2 from 3.4% to 3.7%. TiO2−x samples deposited at room temperature exhibited amorphous characteristics. Oxygen deficiency causes a change in the oxidation state and is assumed to decrease the Ti4+ component on the surfaces of TiO2−x films. The oxygen stoichiometry (x) in TiO2−x films decreased from 0.35 to 0.05 with increasing the R O2 level from 3.4% to 3.7%, respectively. In TiO2−x−test-patterned samples, the resistivity decreased with the temperature, confirming the typical semiconducting property. The bolometric properties of the resistivity, temperature coefficient of resistance (TCR), and the flicker (1/ f) noise parameter were determined at different x values in TiO2−x samples. The rate of TCR dependency with regard to the 1/ f noise parameter is a universal bolometric parameter (β), acting as the dynamic element in a bolometer. It is high when a sample has a relatively low resistivity (0.82 Ω·cm) and a lower 1/ f noise parameter (3.16   ×   10−12). The results of this study indicate that reactively sputtered TiO2−x is a viable bolometric material for uncooled IR image sensor devices. (paper)

  10. Deposition of TiN, TiC, and TiO2 films by filtered arc evaporation

    A filtered arc deposition process was used in the reactive deposition of macroparticle-free TiO2, TiN, and TiC films. The TiO2 films were reactively deposited by arc evaporation of titanium in an oxygen atmosphere. The films deposited onto glass substrates heated to 350degC had a rutile structure and a refractive index n633 of 2.735 and extinction coefficient k633 of 0.07. Films of TiN and TiC were prepared by reactive evaporation in nitrogen and methane respectively. The lattice parameters and preferred orientations of the deposited films were measured as a function of negative substrate bias. The films were characterized by microhardness measurements, X-ray photoelectron spectroscopy and X-ray diffraction. (orig.)

  11. Enhanced electron transport in mesoporous TiO2 films modified by sol-gel necking for dye-sensitized solar cells.

    An, Sang-Yeop; Park, Jeong-Hyun; Kim, Jae-Hong; Choi, Chel-Jong; Kim, Hyunsoo; Ahn, Kwang-Soon

    2012-04-01

    Mesoporous TiO2 films modified via sol-gel necking were fabricated by dispersing Ti tetra-isopropoxide (TTIP; 8 to 16 wt% over TiO2) with TiO2 nanoparticles in isopropyl alcohol. The dye-sensitized solar cells (DSSCs) with 13 wt% TTIP-modified TiO2 film exhibited significantly improved overall energy conversion efficiency, despite having less adsorbed dye when compared with DSSCs with untreated and TiCl4 post-treated TiO2 films. The improvement can be attributed to the sol-gel necking (or interconnection) between the nanoparticles which leads to a much faster electron transport and a suppression of the recombination (or back electron transfer) between the TiO2 and electrolyte. PMID:22849132

  12. Band-gap narrowing of TiO2 films induced by N-doping

    N-doped TiO2 films were deposited on n + -GaN/Al2O3 substrates by reactive magnetron sputtering and subsequently crystallized by annealing at 550 oC in flowing N2 gas. The N-doping concentration was ∼8.8%, as determined from X-ray photoelectron spectroscopy measurements. Deep-level optical spectroscopy measurements revealed two characteristic deep levels located at 1.18 and 2.48 eV below the conduction band. The 1.18 eV level is probably attributable to the O vacancy state and can be active as an efficient generation-recombination center. Additionally, the 2.48 eV band is newly introduced by the N-doping and contributes to band-gap narrowing by mixing with the O 2p valence band

  13. Growth and structure of MBE grown TiO2 anatase films with rutile nano-crystallites

    Shao, Rui; Wang, Chong M.; McCready, David E.; Droubay, Timothy C.; Chambers, Scott A.

    2007-03-15

    We have grown TiO2 anatase films with rutile nanocrystalline inclusions using molecular beam epitaxy under different growth conditions. This model system is important for investigating the role of rutile/anatase interfaces in heterogeneous photocatalysis. To control the film structure, we grew a pure anatase (001) layer at a slow rate and then increased the growth rate to drive the nucleation of rutile particles. Structure analysis indicates that the rutile phase has four preferred orientations in the anatase film.

  14. Photocatalytic Activity of Sol-Gel TiO2 Thin Films Deposited on Soda Lime Glass and Soda Lime Glass Precoated with a SiO2 Layer

    Novotná, P.; Krýsa, J.; Maixner, J.; Klusoň, Petr; Novák, P.

    2010-01-01

    Roč. 201, 16-17 (2010), s. 2570-2575. ISSN 0257-8972 R&D Projects: GA AV ČR KAN400720701 Institutional research plan: CEZ:AV0Z40720504 Keywords : sol-gel * thin layers * titanium dioxide Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.135, year: 2010

  15. Enhanced photocatalytic activity of TiO2 films by modification with polyethylene glycol

    Álvaro A. Ramírez-Santos; Próspero Acevedo-Peña; Elcy M. Córdoba

    2012-01-01

    Titanium dioxide porous thin films on the Anatase phase were deposited onto glass slides by the sol-gel method assisted with polyethylene glycol (PEG). The dip-coated films were characterized using scanning electron microscopy (SEM), thermogravimetric analysis (TGA and DTG), UV-visible spectroscopy and X-ray diffraction (XRD). The photocatalytic activity of the films was determined by means of methyl-orange oxidation tests. The resultant PEG-modified films were crack-free and developed a poro...

  16. UV-Vis and Photoluminescent Spectra of TiO2 Films

    ZHAO Qing-nan; LI Chun-ling; LIU Bao-shun; ZHAO Xiu-jian

    2003-01-01

    TiO2 films have been deposited on glass substrates using DC reactive magnetron sputtering at different oxygen partial pressures from 0.10Pa to 0.65Pa.The transmittance (UV-vis) and photoluminescence (PL) spectra of the films were recorded.The results of the UV-vis spectra show that the deposition rate of the films decreased at oxygen partial pressure P(O2)≥0.15Pa,the band gap increased from 3.48eV to 3.68eV for direct transition and from 3.27eV to 3.34eV for indirect transition with increasing the oxygen partial pressure.The PL spectra show convincingly that the transtion for films was indirect,and there were some oxygen defect energy levels at the band gap of the films.With increasing the O2 partial pressure,the defect energy levels decreased.For the films sputtered at 0.35 and 0.65Pa there were two defect energy levels at 2.63eV and 2.41eV,corresponding to 0.72eV and 0.94eV below the conduction band for a band gap of 3.35eV,respectively.For the films sputtered at 0.10Pa and 0.15Pa,there was an energy band formed between 3.12eV and 2.06eV,corresponding to 0.23eV and 1.29eV below the conduction band.

  17. Tuning the optical bandgap of TiO2-TiN composite films as photocatalyst in the visible light

    Zheng Xie

    2013-06-01

    Full Text Available TiO2-TiN composite catalysts were prepared by oxidizing the TiN films in air at 350 °C. By adjusting the oxidation time to control the oxidation stage of TiN films, the optical band gap of the TiO2-TiN composites can be varied in a wide range from 1.68 eV to 3.23 eV. These composite films all showed red shift in photo-response towards the visible region, and depending on the optical band gap, some composite films exhibited good catalytic activity in the visible light region. This study provides a simple but effective method to prepare film photocatalyst working in visible light.

  18. TiO2 nanotube formation by Ti film anodization and their transport properties for dye-sensitized solar cells

    Iraj, M.; Kolahdouz, M.; Asl-Soleimani, E.; Esmaeili, E.; Kolahdouz Esfahani, Z.

    2016-01-01

    In this paper, we present the synthesis of TiO2 nanotube (NT) arrays formed by anodization of Ti film deposited on a fluorine-doped tin oxide-coated glass substrate by direct current magnetron sputtering. NH4F/ethylene glycol electrolyte was used to demonstrate the growth of stable nanotubes at room

  19. Photocatalytic and photoelectrochemical properties of sol–gel TiO2 films of controlled thickness and porosity

    Krýsa, J.; Baudyš, M.; Zlámal, M.; Krýsová, Hana; Morozová, Magdalena; Klusoň, Petr

    2014-01-01

    Roč. 230, JUL 2014 (2014), s. 2-7. ISSN 0920-5861 Institutional support: RVO:61388955 ; RVO:67985858 Keywords : TiO2 film * Sol-gel * Thickness Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.893, year: 2014

  20. Electrochemically synthesized visible light absorbing vertically aligned N-doped TiO2 nanotube array films

    Graphical abstract: Display Omitted Highlights: ► Single step electrochemical synthesis of N-doped TiO2 nanotube array films. ► Effective substitutional N-doping achieved. ► Different N-concentrations were achieved by varying the N-precursor concentration in the electrolyte. ► Visible light absorption observed at high N-doping. -- Abstract: Visible light absorbing vertically aligned N-doped anatase nanotube array thin films were synthesized by anodizing Ti foils in ethylene glycol + NH4F + water mixture containing urea as nitrogen source. Different nitrogen concentrations were achieved by varying the urea content in the electrolyte. The structure, morphology, composition and optical band gap of the nanotube arrays were determined by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and diffuse reflectance spectroscopy, respectively. The substitution of O2− ions by N3− ions in the anion sublattice as well as the formulae of the doped samples was confirmed from the results of XPS. The optical band gap of the nanotube arrays was found to decrease with N-concentration. The sample with the highest concentration corresponding to the formula TiO1.83N0.14 showed two regions in the Tauc's plot indicating the presence of interband states.

  1. The directed preparation of TiO2 nanotubes film on FTO substrate via hydrothermal method for gas sensing application

    Pham Van Viet

    2016-04-01

    Full Text Available In this research, we directly synthesized TiO2 nanotubes film on Fluorine doped Tin oxide (FTO substrate via hydrothermal method from commercial TiO2 in NaOH solution at 135 ℃ for 24 hours. The samples were characterized by X-ray diffraction (XRD pattern, field emission scanning electron microscopy (FESEM and transmitting electron microscopy (TEM. The average diameter of TiO2 nanotubes (TNTs is about 10–12 nm and their length is about a few hundred nanometers. The sensitivity ability of TNTs increases as the gas concentration increases and developing to the highest sensitivity of TNTs is 2.4 at 700 ppm of the ethanol concentration. The same as the gas concentration, the sensitivity of TNTs increases when the temperature increases. Besides, the sensitivity of samples at 250 ℃ is doubled compared to samples determined at 100 ℃.

  2. Self-Cleaning Effect of Solid Immersion Lens Using Photocatalyst TiO2 Film for Near-Field Recording

    Hong, Hyun-Guk; Kim, Young-Joo

    2008-07-01

    A novel approach using the self-cleaning effect of photocatalyst TiO2 film was proposed and studied experimentally to solve the critical contamination issues in solid immersion lens (SIL) based near-field recording (NFR). To evaluate the feasibility of the self-cleaning approach, the surface of a hemispherical (half-ball) SIL and a glass disk were coated with TiO2 film which constituted the final layer of an antireflection (AR) coating for better optical transmittance. The hydrophilic property of the TiO2-coated SIL and disk was confirmed by the contact angle measurement with deionized water after thermal treatment to form an anatase structure and by the irradiation of UV light. To determine the effectiveness of the self-cleaning effect, a removal test was conducted with different contaminants such as a fingerprint and laser toner particles. The effects of the wavelength and intensity of UV light were tested over a range of irradiation times. The air flow during the rotation of the disk was also helpful for removing the contaminants. From the experimental results, it was confirmed that the self-cleaning effect of photocatalyst TiO2 film is very effective for removing organic contaminants from the surfaces of an SIL and disk, which means that this approach can be applied to SIL-based NFR systems.

  3. Effect of Aging Time and Film Thickness on the Photoelectrochemical Properties of TiO2 Sol-Gel Photoanodes

    D. Regonini

    2014-01-01

    Full Text Available This work has focused on the investigation of a non-aqueous based sol-gel process to produce TiO2 based photoelectrodes for solar water splitting. In particular, the effect of the aging time of the sol and TiO2 film thickness on the photoelectrochemical properties of the photoanodes has been investigated. In order to achieve optimal performances (i.e., photocurrent density up to 570 µA/cm2 and IPCE of 26% at 300 nm, the sol needs to be aged for 3 to 6 h, before being dip-coated to produce the photoanodes. The importance of the aging time can also be appreciated from the optical properties of the TiO2 films; the absorbance threshold of the sol-gel aged for 3–6 h is slightly shifted towards longer wavelenghts in comparison to 0 h aging. Aging is necessary to build up a well-interconnected sol-gel network which finally leads to a photoelectrode with optimized light absorption and electron collection properties. This is also confirmed by the higher IPCE signal of aged photoelectrodes, especially below 340 nm. Among thicknesses considered, there is no apparent significant difference in the photoresponse (photocurrent density and IPCE of the TiO2 sol-gel films.

  4. Optical absorption and ultrafast carrier dynamics characterization of CdSe quantum dots deposited on different morphologies of nanostructured TiO2 films

    In this study, CdSe QDs were chemically adsorbed onto the inverse opal TiO2 film as well as the common nanocrystalline TiO2 film. The optical absorption studied by using photoacoustic (PA) spectroscopy implies the growing and larger amount of CdSe QDs onto inverse opal TiO2 by increasing deposition time. For the same deposition time, the growth of CdSe QD size are independent on TiO2 matrixes, but largely deposited on the common nanocrystalline TiO2 film than the inverse opal TiO2. Ultrafast carrier dynamics shows a fast (hole) decay process and a slow (electron) decay process with lifetimes of a few ps and a few tens to hundreds ps, respectively. With increasing deposition time, regarding larger size and amount of CdSe QDs, the time constant of these two processes become longer for CdSe deposited inverse opal TiO2 samples. However, for the same deposition time, CdSe deposited inverse opal TiO2 have the shorter lifetime of both hole and electron decay processes compared to one on nanocrystalline TiO2, showing that the amount of CdSe QDs, the interfaces between CdSe QDs, play important role in carrier relaxation

  5. CdSxSe1−x alloyed quantum dots-sensitized solar cells based on different architectures of anodic oxidation TiO2 film

    Nanostructured TiO2 translucent films with different architectures including TiO2 nanotube (NT), TiO2 nanowire (NW), and TiO2 nanowire/nanotube (NW/NT) have been produced by second electrochemical oxidization of TiO2 NT with diameter around 90–110 nm via modulation of applied voltage. These TiO2 architectures are sensitized with CdSxSe1−x alloyed quantum dots (QDs) in sizes of around 3–5 nm aiming to tune the response of the photoelectrochemical properties in the visible region. One-step hydrothermal method facilitates the deposition of CdSxSe1−x QDs onto TiO2 films. These CdSxSe1−x QDs exhibit a tunable range of light absorption with changing the feed molar ratio of S:Se in precursor solution, and inject electrons into TiO2 films upon excitation with visible light, enabling their application as photosensitizers in sensitized solar cells. Power conversion efficiency (PCE) of 2.00, 1.72, and 1.06 % are achieved with CdSxSe1−x (obtained with S:Se = 0:4) alloyed QDs sensitized solar cells based on TiO2 NW/NT, TiO2 NW, and TiO2 NT architectures, respectively. The significant enhancement of power conversion efficiency obtained with the CdSxSe1−x/TiO2 NW/NT solar cell can be attributed to the extended absorption of light region tuned by CdSxSe1−x alloyed QDs and enlarged deposition of QDs and efficient electrons transport provided by TiO2 NW/NT architecture

  6. Synergistic reinforcing effect of TiO2 and montmorillonite on potato starch nanocomposite films: Thermal, mechanical and barrier properties.

    Oleyaei, Seyed Amir; Almasi, Hadi; Ghanbarzadeh, Babak; Moayedi, Ali Akbar

    2016-11-01

    In this study, ternary potato starch (PS) bionanocomposite films containing two types of nanoparticles, sodium montmorillonite (MMT), one-dimensional (1D) clay platelets, (3 and 5wt%) and TiO2, three-dimensional (3D) nanospheres, (0.5, 1 and 2wt%), are prepared using solvent casting method. X-ray diffraction (XRD) test confirms the completely exfoliated structure formed in the PS-MMT nanocomposites containing 3 and 5% MMT. The success of the formation of new hydrogen bonds between the hydroxyl groups of starch and nanofillers is confirmed by Fourier transform infrared (FTIR) spectroscopy. Tensile strength (TS), elongation at break (EB), glass transition temperature (Tg), and melting point (Tm) of the films are also enhanced after MMT and TiO2 incorporation. The water vapor permeability (WVP) and the visible, UVA, UVB and UVC lights transmittance decreases upon TiO2 and MMT content increasing. Generally, a synergistic effect is observed between MMT and TiO2 at lower concentrations of MMT. PMID:27516271

  7. Synthesis and characterization of erbium-doped SiO2-TiO2 thin films prepared by sol-gel and dip-coating techniques onto commercial glass substrates as a route for obtaining active GRadient-INdex materials

    In this work, SiO2-TiO2 films doped with erbium were prepared by dip-coating sol-gel process onto commercial glass substrates. The surface morphology of the films was characterized using atomic force microscopy, while thickness, refractive index, extinction coefficient and porosity of the films were determined by ellipsometric measurements in a wavelength region of 400-1000 nm. Optical constants and porosity were found to vary with erbium concentration. The proof of principle presented in this paper is applicable to systems of different nature by tailoring the sol-gel precursors in such a way that active GRadient-INdex media described by a complex, parabolic-like refractive index distribution for beam shaping purposes is obtained. - Highlights: • Sol-gel route for preparation of active GRadient-INdex materials is proposed. • SiO2-TiO2 films doped with erbium were prepared by dipping onto commercial glasses. • Morphological and optical characterization of the samples was performed. • Optical constants and porosity were found to vary with erbium concentration. • Refractive index diminishes with dopant content; the contrary occurs for porosity

  8. Transparent conductive Nb-doped TiO2 films deposited by RF magnetron co-sputtering

    Wan, Guangmiao; Wang, Shenwei; Zhang, Xinwu; Huang, Miaoling; Zhang, Yanwei; Duan, Wubiao; Yi, Lixin

    2015-12-01

    In this work, Nb-doped TiO2 films were deposited on glass substrates utilizing RF magnetron co-sputtering with a TiO2 target and a Nb target. In order to study the effect of Nb concentration, four groups of films with different Nb concentration were prepared and annealed in N2 at 500 °C. Crystal structure, surface morphology, electrical and optical property of the films were characterized. The lowest resistivity was measured to be 1.2 × 10-3 Ω cm at the Nb concentration of 7.0 at.%. Meanwhile, Hall mobility and carrier density were 2.0 cm2/Vs and 2.6 × 1021 cm-3, respectively.

  9. Dye-sensitized solar cells based on nanocrystalline TiO2 films surface treated with Al3+ ions: photovoltage and electron transport studies

    Nanocrystalline TiO2 films, surface modified with Al3+, were manufactured by depositing a TiO2 suspension containing small amounts of aluminum nitrate or aluminum chloride onto conducting glass substrates, followed by drying, compression, and finally heating to 530 oC. Electrodes prepared with TiO2 nanoparticles coated with less than 0.3 wt % aluminum oxide with respect to TiO2 improved the efficiency of the dye sensitized solar cell. This amount corresponds to less than a monolayer of aluminum oxide. Thus, the Al ions terminate the TiO2 surface rather than form a distinct aluminum oxide layer. The aluminum ion surface treatment affects the solar cell in different ways: the potential of the conduction band is shifted, the electron lifetime is increased, and the electron transport is slower when aluminum ions are present between interconnected TiO2 particles. (author)

  10. Preparation and Characterization of the Thin Nanocrystalline TiO2 Layers

    Šolcová, Olga; Matějová, Lenka; Klusoň, Petr; Matěj, Z.; Strýhal, Z.; Pavlík, J.; Cajthaml, Tomáš

    Dordrecht: Springer, 2008 - (Innocenzi, P.; Zub, Y.; Kessler, V.), s. 441-446 ISBN 978-1-4020-8521-5. ISSN 1871-4668. [NATO Advanced Research Workshop n Sol-Gel Approaches to Materials for Pollution Control, Water Purification and Soil Remediation. Kyiv (UA), 25.10.2007-27.10.2007] Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z50200510 Keywords : sol-gel method * thin films * texture Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  11. Characterization of N,C-codoped TiO2 films prepared by reactive DC magnetron sputtering

    Titanium dioxide (TiO2) films are deposited by codoping nitrogen and carbon on indium tin oxide-coated substrates as visible light (Vis)-enabled catalysts. The X-ray diffraction peak intensity of the preferential orientation in (2 1 1) plane declines when the topmost 1.0 μm layer of the film is ground off. The decrease in the crystallite size and the crystallinity of anatase TiO2 film is also evidenced by a shift towards the high wave number and broadening of the Raman spectra. Low doping concentrations of N (1.3%) and C (1.8%) are estimated by X-ray photoelectron spectroscopy (XPS) which displays an N 1s peak at 396.8 eV and a C 1s peak at 282.1 eV, respectively. This is attributed to the substitution of the oxygen sites with nitrogen and carbon, which is believed to be responsible for the Vis photocatalytic activity into a wavelength of >500 nm. The cross-sectional transmission electron microscopy images show larger pores at the grain boundaries and in larger columnar crystals than in the undoped TiO2 film. All of these results indicate that porosity, crystallinity and shift in the preferential orientation are more pronounced close to the surface than close to the bottom of the sample. Wettability upon measurement of the water contact angle, methylene blue degradation and radical formation tests under both ultraviolet and Vis irradiation demonstrate that the topmost surface renders not only a larger reactive surface area but also a better carrier transport route than the rest of the film, improving its photocatalytic activity. These results show that surface porosity of the film is dominant than the tailoring of the photocatalytic activities of N,C-codoped TiO2 catalysts.

  12. Characterization of TiO2/Ta2O5 Films Synthesized by Ion Beam on NiTi Alloy for Biomedical Applications

    Jingxiao LIU; Jihua CHEN; Dazhi YANG; Weiqiang WANG; Yinong WANG; Yingji CAI

    2001-01-01

    The biocompatibility of implants is determined by their corrosion resistance and surface characteristics. in this study, the surface composition, morphology and microstructure of TiO2/Ta2O5 films synthesized by ion beam enhanced deposition on NiTi alloy were studied. The scratch test results indicate that the interface adhesive strength of TiO2/Ta2O5 film increases with the increasing Ta content. The electrochemical corrosion measurement shows that the TiO2-36%Ta2O5 film is optimal for improving corrosion resistance of NiTi alloy.

  13. Electronic properties of atomic layer deposition films, anatase and rutile TiO2 studied by resonant photoemission spectroscopy

    Das, C.; Richter, M.; Tallarida, M.; Schmeisser, D.

    2016-07-01

    The TiO2 films are prepared by atomic layer deposition (ALD) method using titanium isopropoxide precursors at 250 °C and analyzed using resonant photoemission spectroscopy (resPES). We report on the Ti2p and O1s core levels, on the valence band (VB) spectra and x-ray absorption spectroscopy (XAS) data, and on the resonant photoelectron spectroscopy (resPES) profiles at the O1s and the Ti3p absorption edges. We determine the elemental abundance, the position of the VB maxima, the partial density of states (PDOS) in the VB and in the conduction band (CB) and collect these data in a band scheme. In addition, we analyze the band-gap states as well as the intrinsic states due to polarons and charge-transfer excitations. These states are found to cause multiple Auger decay processes upon resonant excitation. We identify several of these processes and determine their relative contribution to the Auger signal quantitatively. As our resPES data allow a quantitative analysis of these defect states, we determine the relative abundance of the PDOS in the VB and in CB and also the charge neutrality level. The anatase and rutile polymorphs of TiO2 are analyzed in the same way as the TiO2 ALD layer. The electronic properties of the TiO2 ALD layer are compared with the anatase and rutile polymorphs of TiO2. In our comparative study, we find that ALD has its own characteristic electronic structure that is distinct from that of anatase and rutile. However, many details of the electronic structure are comparable and we benefit from our spectroscopic data and our careful analysis to find these differences. These can be attributed to a stronger hybridization of the O2p and Ti3d4s states for the ALD films when compared to the anatase and rutile polymorphs.

  14. Photoelectrochemical characterization and photocatalytic properties of mesoporous TiO2/ZrO2 films

    Natalie Smirnova; Yuriy Gnatyuk; Anna Eremenko; Gennadiy Kolbasov; Vera Vorobetz; Irina Kolbasova; Olga Linyucheva

    2006-01-01

    Optically transparent, crack-free mesoporous titania and zirconia-doped titania thin film photocatalysts were fabricated by sol-gel technique, using nonionic amphiphilic block copolymer Pluronic P123 as template. The structural and optical properties of these films were characterized using SEM, low-angle XRD, and UV/Vis spectroscopy, hexane adsorption investigation. Band gap energy and the position of flatband potentials were estimated by photoelectrochemical measurements...

  15. Effects of SiO_2 and TiO_2 on resistance stabilities of flexible indium-tin-oxide films prepared by ion assisted deposition

    LI Yuqiong; YU Zhinong; WANG Wuyu; FAN Yuejiang; DING Zhao; XUE Wei

    2009-01-01

    Inorganic buffer layers such as SiO_2 or TiO_2 and transparent conductive indium-tin-oxide (ITO) films were prepared on polyethylene terephthalate (PET) substrates by ion assisted deposition (LAD) at room temperature, and the effects of SiO_2 and TiO_2 on the bending resis-tance performance of flexible ITO films were investigated. The results show that ITO films with SiO_2 or TiO_2 buffer layer have better resis-tance stabihties compared to ones without the buffer layer when the ITO films are inwards bent at a bending radius more than 1.2 cm and when the ITO films are outwards bent at a bending radius from 0.8 cm to 1.2 cm. ITO films with SiO_2 buffer layer have better resistance sta-bilities compared to ones with TiO_2 buffer layer after the ITO Films are bent several hundreds of cycles at the same bending radius, for the adhesion of SiO_2 is stronger than that of TiO_2. The compressive stress resulted from inward bending leads to the formation of more defects in the ITO films compared with the tensile stress arising from outward bending. SiO_2 and TiO_2 buffer layers can effectively improve the crystal-linity of ITO films in (400), (440) directions.

  16. Reduced electrical resistivity in TiO2:Nb/ZnO:Ga film by thermal annealing

    Yamada, Yasuji; Funaki, Shuhei; Ichiyanagi, Seiji; Kikuchi, Hiroki; Inoue, Sota

    2014-01-01

    Layered films consisting of transparent conducting oxides, Ga-doped ZnO (GZO) and Nb-doped TiO2 (TNO), were fabricated on glass substrates and their electrical properties were investigated. As-deposited TNO/GZO films showed the mean resistivity of TNO and GZO films. Thermal annealing reduced the resistivity of these films; however, TNO/GZO films exhibited the lowest value among them. The carrier concentration and Hall mobility of TNO/GZO films increased with the reduction in electrical resistivity. The thickness dependence, annealing temperature dependence, and crystalline orientation of the TNO and GZO layers in TNO/GZO films indicated that the improvement of the electrical properties of the GZO underlayer contributed to the resistivity reduction behavior of TNO/GZO films induced by thermal annealing.

  17. Effect of Isopropanol on Microstructure and Activity of TiO2 Films with Dominant {001} Facets for Photocatalytic Degradation of Bezafibrate

    Murtaza Sayed

    2014-01-01

    Full Text Available Titanium dioxide (TiO2 films with dominant {001} facets coated on a titanium sheet (Ti were synthesized with the simple hydrothermal method by using Ti as the precursor and substrate. The effect of addition of isopropanol into the hydrothermal solution on the structure, photocatalytic activity, and stability of as-synthesized TiO2 films was investigated. The presence of isopropanol obviously influenced the microstructure of as-synthesized TiO2 films, which was converted from microspheres into irregular close stack of truncated tetrahedrons. And the percentage of exposed {001} facets calculated from the Raman spectra increased from 48.2% to 57%. Accordingly, the TiO2 films prepared with addition of isopropanol showed high and stable photocatalytic activity, which is nearly 2.6 times as that of the conventional P25 TiO2 coated on Ti-substrate. In addition, the photocatalytic activity of as-synthesized TiO2 films was greatly enhanced after calcination treatment at 600°C, which can be attributed to removal of fluoride ions and organic residuals adsorbed on the surface of the catalyst. Photoluminescence (PL technique was used for the detection of produced hydroxyl radicals (•OH on the surface of UV-illuminated TiO2 using terephthalic acid as probe molecule. The photocatalytic degradation intermediates of bezafibrate were analyzed by an ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS, and accordingly the degradation pathways were proposed.

  18. Influences of alcoholic solvents on spray pyrolysis deposition of TiO2 blocking layer films for solid-state dye-sensitized solar cells

    Influences of alcoholic solvents for titanium diisopropoxide bis(acetylacetonate) (TPA) precursor solutions on the spray pyrolysis deposited TiO2 films and the photovoltaic performance of the solid-state dye-sensitized solar cells (SDSCs) using these TiO2 films as the blocking layers were investigated. Smooth TiO2 films were obtained by spray pyrolysis deposition of a TPA solution in isopropanol (IPA) at a relatively low temperature of 260 °C. On the other hand, when ethanol was used as solvent, the TiO2 films fabricated at the same temperature showed much rougher surfaces with many pinholes. Our results showed that ethanol reacts with TPA to form titanium diethoxide bis(acetylacetonate) (TEA), which requires a higher thermal decomposition temperature than that of TPA. SDSCs with TiO2 blocking layer films fabricated using a TPA solution in IPA showed higher power conversion efficiencies with smaller variations. - Graphical abstract: Alcoholic solvents used for the TiO2 precursor play a critical role in determining the surface morphology of blocking layers and thus the photovoltaic performance of the SDSCs. Highlights: ► Solvent influences morphology of spray pyrolysis deposited TiO2 blocking layer. ► Ethanol reacts with TPA, resulting poor quality of blocking layer. ► Isopropanol is better than ethanol for obtaining smooth blocking layer. ► SDSC with blocking layer made with isopropanol showed better performance.

  19. Thin Films

    M. Benmouss

    2003-01-01

    the optical absorption are consistent with the film color changes. Finally, the optical and electrochromic properties of the films prepared by this method are compared with those of our sputtered films already studied and with other works.

  20. A vapor phase hydrothermal modification method converting a honeycomb structured hybrid film into photoactive TiO2 film.

    Zhao, Huijun; Shen, Yanming; Zhang, Shanqing; Zhang, Haimin

    2009-09-15

    Transforming an organic/inorganic hybrid material into a pure inorganic material without losing its original structure is of interest for a range of applications. In this work, a simple and effective vapor phase hydrothermal method was developed to transform a 3D honeycomb structured PS/TTIP hybrid film into a photoactive TiO2 film without dismantling the originally templated 3D structure. The method utilizes the vapor phase hydrothermal process to create titania network/clusters with sufficient mechanical strength via the formation of Ti-oxo bridges. The organic components of the sample can be removed by means of pyrolysis while perfectly maintaining the original 3D honeycomb structure. The resultant film can be directly used for photocatalysis applications and could be further modified for other applications. In principle, this method can be used to preserve 3D structures of other organic/inorganic hybrid films during their conversion to pure inorganic films via a pyrolysis process, if mechanically strong networks can be formed as a result of hydrolysis reactions. The ability to preserve the preferred 3D structure during the subsequent conversion processes enables realization of the full benefit of unique architectures created by a templating method. PMID:19496571

  1. Rewriting of low electrical resistance lines on TiO2 film by writing and erasing with femtosecond and CW fiber lasers

    Highlights: • A rewriting process on TiO2 film was developed with femtosecond and CW fiber lasers. • Low electrical resistance lines are written on TiO2 film with a femtosecond laser. • Low electrical resistance lines are erased on TiO2 film with a CW fiber laser. • Low electrical resistance lines can be rewritten with a femtosecond laser. - Abstract: A rewriting process was developed for reduced electrical resistance lines on a titanium dioxide (TiO2) film with femtosecond and CW fiber lasers. In this process, lines are written on TiO2 film by femtosecond laser irradiation, where the lines have a lower electrical resistance than the surrounding film. By heating with a CW fiber laser in air, the low electrical resistance lines are erased and their electrical resistances increase. When the erased areas on the TiO2 film are irradiated with the femtosecond laser, the lower electrical resistance lines can be rewritten on the film surface

  2. Enhanced photocatalytic activity of TiO2 films by modification with polyethylene glycol

    Álvaro A. Ramírez-Santos

    2012-01-01

    Full Text Available Titanium dioxide porous thin films on the Anatase phase were deposited onto glass slides by the sol-gel method assisted with polyethylene glycol (PEG. The dip-coated films were characterized using scanning electron microscopy (SEM, thermogravimetric analysis (TGA and DTG, UV-visible spectroscopy and X-ray diffraction (XRD. The photocatalytic activity of the films was determined by means of methyl-orange oxidation tests. The resultant PEG-modified films were crack-free and developed a porous structure after calcination at 500 °C. Photo-oxidation tests showed the dependency of catalytic activity of the films on the number of layers (thickness and porosity, i.e. of the interfacial area.

  3. Nanoscale TiO2 films and their application in remediation of organic pollutants

    Photocatalysis is an advanced process for treatment of air, wastewater, and drinking water, the primary advantage being its ability to mineralize many pollutants. Among several nanoscale arrangements of photocatalysts, there has been a strong push to develop them as thin films be...

  4. Mechanism and behaviors of Cr3+-doped TiO2

    CHEN Jian-hua; WANG Xiao-lin; GONG Zhu-qing

    2005-01-01

    TiO2 powder and TiO2 thin film on the surface of glazed ceramic tile were prepared by sol-gel method.The influences of different doping Cr3+ concentration on the photocatalytic activity of TiO2 were discussed, UV-visible and X-ray diffraction analysis were used to test the performance of TiO2 powder and film. The results indicate that photocatalytic activity of doping Cr3+-TiO2 thin film is higher than that of powder, and the interaction between Cr3+-doped and substrate can greatly enhance the photocatalytic activity. The results of X-ray diffraction and photoabsorption show that the Cr3+ -doped energy level in TiO2 is 0. 62 eV high from the top of valence band, which belongs to the type of deep energy level doping. On the basis of the semiconductor energy level theory and Cr3+ dopant energy level, the semiconductor energy level model of Cr3+ in TiO2 powder and thin film were established, and the doping mechanisms of Cr3+-doped in TiO2 powder and thin film were analyzed.

  5. Structural and electrical properties of Nb-doped TiO2 films sputtered with plasma emission control

    A technique to deposit Nb-doped films of TiO2 by radio-frequency magnetron sputtering was investigated. Nb wires are put onto the sputter track of a metallic titanium target and the oxidation state of the target is controlled by the intensity of a Ti line from the plasma emission. The sputtered films are analyzed with X-ray diffraction, RBS (Rutherford back scattering), energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and SEM (scanning electron microscopy). After post-heating at 400 °C, all films exhibit the anatase structure. The films are polycrystalline with a Nb/[Nb + Ti] content from 2 to 17 at.%. RBS and SEM indicate that the films consist of two sub-layers with the surface layer containing more Nb and exhibiting a clearer columnar structure. There is an optimum oxidation state of the target in the transition region between metallic and oxidic modes where the lowest resistivity of 7 × 10−4 Ωcm is achieved. Nb is incorporated as Nb5+ into the anatase lattice, but in suboptimal films, Ti vacancies (acceptors) may compensate the donor effect of Nb. The oxygen content in the films is higher than for stoichiometric TiO2. O interstitials may increase the mass density of the films. The lattice parameter a and the unit cell volume increase with the Nb content in a similar manner as observed for single crystals of TiO2:Nb. - Highlights: • Nb-doped TiO2 (pure anatase) films are grown by radio-frequency magnetron sputtering. • The content Nb/(Ti + Nb) ranges from 2 to 17 at.% for films post-heated at 400 °C. • Unit cell volume and conductivity increase with the Nb content in the films. • The oxidation state of the metallic target is controlled using plasma emission. • Best electrical properties (ρ = 7 × 10−4 Ωcm) are obtained for a 68%-oxidized target

  6. Tuning the Optical Properties of Mesoporous TiO2 Films by Nanoscale Engineering

    Schwenzer, Birgit; Wang, Liang; Swensen, James S.; Padmaperuma, Asanga B.; Silverman, Gary; Korotkov, Roman; Gaspar, Daniel J.

    2012-07-03

    Introducing mesoscale pores into spincoated titanium dioxide films, prepared by spincoating different sol-gel precursor solutions on silicon substrates and subsequent annealing at 350 C, 400 C or 450 C, respectively, affects several optical properties of the material. The change in refractive index observed for different mesoporous anatase films directly correlates with changes in pore size, but is also in a more complex manner influenced by the film thickness and the density of pores within the films. Additionally, the band gap of the films is blueshifted by the stress the introduction of pores exerts on the inorganic matrix. The differently sized pores were templated by Pluronic{reg_sign} block copolymers in the solgel solutions and tuned by employing different annealing temperatures for the film preparation. This study focused on elucidating the effect different templating materials (F127 and P123) have on the pore size of the final mesoporous titania film, and on understanding the relation of varying polymer concentration (taking P123 as an example) in the sol-gel solution to the pore concentration and size in the resultant titania film. Titania thin film samples or corresponding titanium dioxide powders were characterized by X-ray diffraction, nitrogen adsorption, ellipsometery, UV/Vis spectrometry and other techniques to understand the interplay between mesoporosity and optical properties.

  7. Integrated TiO2 resonators for visible photonics

    Choy, Jennifer T; Deotare, Parag B; Burgess, Ian B; Evans, Christopher C; Mazur, Eric; Loncar, Marko

    2011-01-01

    We demonstrate waveguide-coupled titanium dioxide (TiO2) racetrack resonators with loaded quality factors of 2x10^4 for the visible wavelengths. The structures were fabricated in sputtered TiO2 thin films on oxidized silicon substrates using standard top-down nanofabrication techniques, and passively probed in transmission measurements using a tunable red laser. Devices based on this material could serve as integrated optical elements as well as passive platforms for coupling to visible quantum emitters.

  8. CdS/CdSe Co-sensitized Solar Cells Based on Hierarchically Structured SnO2/TiO2 Hybrid Films.

    Chen, Zeng; Wei, Chaochao; Li, Shengjun; Diao, Chunli; Li, Wei; Kong, Wenping; Zhang, Zhenlong; Zhang, Weifeng

    2016-12-01

    SnO2 nanosheet-structured films were prepared on a fluorine-doped tin oxide (FTO) substrate using ZnO nanosheet as template. The as-prepared SnO2 nanosheets contained plenty of nano-voids and were generally vertical to the substrate. TiO2 nanoparticles were homogeneously deposited into the intervals between the SnO2 nanosheets to prepare a hierarchically structured SnO2/TiO2 hybrid film. The hybrid films were co-sensitized with CdS and CdSe quantum dots. The sensitized solar cells assembled with the SnO2/TiO2 hybrid film showed much higher photoelectricity conversion efficiency than the cells assembled with pure TiO2 films. The lifetime of photoinduced electron was also investigated through electrochemical impedance spectroscopy, which showed that the SnO2/TiO2 hybrid film electrode is as long as the TiO2 film electrode. PMID:27299650

  9. CdS/CdSe Co-sensitized Solar Cells Based on Hierarchically Structured SnO2/TiO2 Hybrid Films

    Chen, Zeng; Wei, Chaochao; Li, Shengjun; Diao, Chunli; Li, Wei; Kong, Wenping; Zhang, Zhenlong; Zhang, Weifeng

    2016-06-01

    SnO2 nanosheet-structured films were prepared on a fluorine-doped tin oxide (FTO) substrate using ZnO nanosheet as template. The as-prepared SnO2 nanosheets contained plenty of nano-voids and were generally vertical to the substrate. TiO2 nanoparticles were homogeneously deposited into the intervals between the SnO2 nanosheets to prepare a hierarchically structured SnO2/TiO2 hybrid film. The hybrid films were co-sensitized with CdS and CdSe quantum dots. The sensitized solar cells assembled with the SnO2/TiO2 hybrid film showed much higher photoelectricity conversion efficiency than the cells assembled with pure TiO2 films. The lifetime of photoinduced electron was also investigated through electrochemical impedance spectroscopy, which showed that the SnO2/TiO2 hybrid film electrode is as long as the TiO2 film electrode.

  10. Enhanced photocurrent production by bio-dyes of photosynthetic macromolecules on designed TiO2 film.

    Yu, Daoyong; Wang, Mengfei; Zhu, Guoliang; Ge, Baosheng; Liu, Shuang; Huang, Fang

    2015-01-01

    The macromolecular pigment-protein complex has the merit of high efficiency for light-energy capture and transfer after long-term photosynthetic evolution. Here bio-dyes of A. platensis photosystem I (PSI) and spinach light-harvesting complex II (LHCII) are spontaneously sensitized on three types of designed TiO2 films, to assess the effects of pigment-protein complex on the performance of bio-dye sensitized solar cells (SSC). Adsorption models of bio-dyes are proposed based on the 3D structures of PSI and LHCII, and the size of particles and inner pores in the TiO2 film. PSI shows its merit of high efficiency for captured energy transfer, charge separation and transfer in the electron transfer chain (ETC), and electron injection from FB to the TiO2 conducting band. After optimization, the best short current (JSC) and photoelectric conversion efficiency (η) of PSI-SSC and LHCII-SSC are 1.31 mA cm(-2) and 0.47%, and 1.51 mA cm(-2) and 0.52%, respectively. The potential for further improvement of this PSI based SSC is significant and could lead to better utilization of solar energy. PMID:25790735

  11. Preparation and characterization of oxide films containing crystalline TiO2 on magnesium alloy by plasma electrolytic oxidation

    Oxide films have been produced on AM60B magnesium alloy using plasma electrolytic oxidation process in an alkaline phosphate electrolyte with and without addition of titania sol. The microstructure and composition of the oxide films were analyzed by Scanning Electron Microscope (SEM), X-ray Photoelectron Spectroscope (XPS) and X-ray Diffraction (XRD). The corrosion resistances of the oxide films were evaluated using potentiodynamic polarization measurements in 3.5 wt% NaCl solution. It is found that the oxide film containing crystalline rutile and anatase TiO2 compounds are produced in an alkaline phosphate electrolyte with addition of titania sol. The oxide film formed in electrolyte with addition of titania sol has more uniform morphology with less structural imperfections than that formed in electrolyte without addition of titania sol. The results of potentiodynamic polarization analysis show that the oxide film formed in the present modified electrolyte is successful in providing superior corrosion resistance for magnesium alloy

  12. Substrate Fermi level effects in photocatalysis on oxides: Properties of ultrathin TiO2/Si films

    Kazazis, D.; Guha, S.; Bojarczuk, N. A.; Zaslavsky, A.; Kim, H.-C.

    2009-08-01

    Photocatalysis has widespread applications from solar cells to photolithography. We studied the photocatalytic properties of TiO2 films of thicknesses down to 2 nm, grown on n-type and p-type silicon wafers, using the oxidation of isopropanol as a model system. Direct in vacuo mass spectrometry measurements were performed under irradiation above the TiO2 bandgap. We present a model consistent with our experimental results, which indicate that only near-surface electron-hole pair generation is relevant and that the reaction rate can be controlled by varying the substrate Fermi level in going from n-type to p-type silicon, by approximately a factor of 2.

  13. Synthesis of mesoporous TiO2/SiO2 hybrid films as an efficient photocatalyst by polymeric micelle assembly.

    Li, Yunqi; Bastakoti, Bishnu Prasad; Imura, Masataka; Hwang, Soo Min; Sun, Ziqi; Kim, Jung Ho; Dou, Shi Xue; Yamauchi, Yusuke

    2014-05-12

    Thermally stable mesoporous TiO2/SiO2 hybrid films with pore size of 50 nm have been synthesized by adopting the polymeric micelle-assembly method. A triblock copolymer, poly(styrene-b-2-vinyl pyridine-b-ethylene oxide), which serves as a template for the mesopores, was utilized to form polymeric micelles. The effective interaction of titanium tetraisopropoxide (TTIP) and tetraethyl orthosilicate (TEOS) with the polymeric micelles enabled us to fabricate stable mesoporous films. By changing the molar ratio of TEOS and TTIP, several mesoporous TiO2/SiO2 hybrid films with different compositions can be synthesized. The presence of amorphous SiO2 phase effectively retards the growth of anatase TiO2 crystal in the pore walls and retains the original mesoporous structure, even at higher temperature (650 °C). These TiO2/SiO2 hybrid films are of very high quality, without any cracks or voids. The addition of SiO2 phase to mesoporous TiO2 films not only adsorbs more organic dyes, but also significantly enhances the photocatalytic activity compared to mesoporous pure TiO2 film without SiO2 phase. PMID:24710980

  14. Electrochemical behavior and corrosion protection performance of bis-[triethoxysilylpropyl] tetrasulfide silane films modified with TiO2 sol on 304 stainless steel

    Highlights: • The TiO2 sol/BTESPT composite films were prepared on 304 SS surface. • TiO2 sol/BTESPT composite films exhibit strong adhesion force and good compactness. • TiO2 sol/BTESPT composite films provided superior corrosion resistance ability. - Abstract: The corrosion protection ability of bis-[triethoxysilylpropyl]tetrasulfide/TiO2 composite films was evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy in this paper. The electrochemical results show that the composite films modified with TiO2 sol exhibited superior corrosion protection performance compared to single bis-[triethoxysilylpropyl]tetrasulfide (BTESPT) silane films. The durability and reaction mechanism of BTESPT films and BTESPT/TiO2 composite films were further studied by electrochemical impedance spectroscopy, scanning electron microscopy, reflection absorption Fourier infrared spectroscopy and X-ray photoelectron spectroscopy, the experimental results revealed the loading of TiO2 sol into the porous part of the silane network, which not only increases the compactness and durability of silane films but also improves the interfacial bonding force due to formation of Si−O−Ti bonds. After 15 days immersion in 3.5 wt.% NaCl solution, the BTESPT/TiO2 composite films still had good corrosion resistance ability

  15. Research on Hydrothermal Decoration of TiO2 Nanotube Films with Nanoplatelet MoS2 Species

    Kovger, Jelena; Naujokaitis, Arnas; Niaura, Gediminas; Juodkazyte, Jurga; Valušis, Gintaras; Jagminas, Arūnas

    2016-01-01

    In this study, novel electrodes were prepared via decoration of nanotubed TiO2 (TiNT) films with crystalline two- dimensional (2D) MoS2 species by a one-step hydrothermal synthesis approach. Obtained products were characterized in detail by scanning electron microscopy, Raman spectro‐ scopy, U-I measurements and X-ray diffraction techniques. The influence of hydrothermal synthesis conditions on the composition and morphology of the products formed in the solution and within the TiNT film are ...

  16. One-Step Formation of WO3-Loaded TiO2 Nanotubes Composite Film for High Photocatalytic Performance

    Wai Hong Lee

    2015-04-01

    Full Text Available High aspect ratio of WO3-loaded TiO2 nanotube arrays have been successfully synthesized using the electrochemical anodization method in an ethylene glycol electrolyte containing 0.5 wt% ammonium fluoride in a range of applied voltage of 10–40 V for 30 min. The novelty of this research works in the one-step formation of WO3-loaded TiO2 nanotube arrays composite film by using tungsten as the cathode material instead of the conventionally used platinum electrode. As compared with platinum, tungsten metal has lower stability, forming dissolved ions (W6+ in the electrolyte. The W6+ ions then move towards the titanium foil and form a coherent deposit on titanium foil. By controlling the oxidation rate and chemical dissolution rate of TiO2 during the electrochemical anodization, the nanotubular structure of TiO2 film could be achieved. In the present study, nanotube arrays were characterized using FESEM, EDAX, XRD, as well as Raman spectroscopy. Based on the results obtained, nanotube arrays with average pore diameter of up to 74 nm and length of 1.6 µm were produced. EDAX confirmed the presence of tungsten element within the nanotube arrays which varied in content from 1.06 at% to 3.29 at%. The photocatalytic activity of the nanotube arrays was then investigated using methyl orange degradation under TUV 96W UV-B Germicidal light irradiation. The nanotube with the highest aspect ratio, geometric surface area factor and at% of tungsten exhibited the highest photocatalytic activity due to more photo-induced electron-hole pairs generated by the larger surface area and because WO3 improves charge separation, reduces charge carrier recombination and increases charge carrier lifetime via accumulation of electrons and holes in the two different metal oxide semiconductor components.

  17. A facile strategy to fabricate plasmonic Cu modified TiO2 nano-flower films for photocatalytic reduction of CO2 to methanol

    Graphical abstract: Photoreduction of CO2 to CH3OH over plasmonic Cu/TiO2 film. - Highlights: • Cu nanoparticles modified TiO2 nano-flower film was prepared by a facile strategy. • Cu nanoparticles can enhance the light absorption and the Raman scattering of TiO2. • Cu nanoparticles can effectively restrain the recombination of the charge carriers. • A synergistic mechanism is proposed for photocatalytic reduction of CO2 on Cu/TiO2 film. - Abstract: Cu nanoparticles (NPs) deposited TiO2 nano-flower films were fabricated using a combination of a hydrothermal method and a microwave-assisted reduction process. The investigations indicated that Cu NPs and TiO2 film both exhibit visible light harvesting properties based on localized surface plasmon resonance (LSPR) of Cu NPs and unique nanostructures of TiO2 film. Fluorescence quenching was observed because the recombination of charge carriers was effectively suppressed by Cu NPs deposition. The experimental results indicate that Cu/TiO2 films exhibit better activity for the photocatalytic reduction of CO2 due to the charge transfer property and LSPR effect of Cu NPs. The CH3OH production rate reached 1.8 μmol cm−2 h−1 (energy efficiency was 0.8%) over 0.5 Cu/TiO2 film under UV and visible light irradiation, which was 6.0 times higher than that observed over pure TiO2 film. In addition, a tentative photocatalytic mechanism is proposed to understand the experimental results over the Cu modified TiO2 nano-flower films

  18. Modifying TiO2 surface architecture by oxygen plasma to increase dye sensitized solar cell efficiency

    Oxygen plasma treatment of TiO2 films has been used to improve the efficiency of dye sensitized solar cells. Both a commercial TiO2 sample and a TiO2 thin film synthesized by a sol-gel technique were treated using a custom built inductively coupled plasma apparatus. X-ray photoelectron spectroscopy revealed that oxygen-plasma treatment increased the number of oxygen functional groups (hydroxyl groups) and introduced some Ti3+ species on the surface of TiO2. A sample solar cell with plasma treated TiO2 showed an overall solar-to-electricity conversion efficiency of 4.3%, about a 13% increase over untreated TiO2. The photon conversion efficiency for the plasma treated TiO2 was 34% higher than untreated TiO2. This enhanced cell-performance is partly due to increased dye adsorption from an increase in surface oxygen functional groups and also may be partly due to Ti3+ states on the surface of TiO2. - Highlights: • Oxygen plasma is used to generate hydroxyl groups on the surface of TiO2 • Parallel study was conducted using a spin coated TiO2 and a Commercial TiO2 film. • The plasma functionalization caused increased dye uptake. • Some species in Ti3+ state are also generated after oxygen plasma. • Dye sensitised solar cell with functionalised electrode showed improved efficiency

  19. Reduced interfacial recombination in dye-sensitized solar cells assisted with NiO:Eu(3+),Tb(3+) coated TiO2 film.

    Yao, Nannan; Huang, Jinzhao; Fu, Ke; Deng, Xiaolong; Ding, Meng; Zhang, Shouwei; Xu, Xijin; Li, Lin

    2016-01-01

    Eu(3+),Tb(3+) doped and undoped NiO films were deposited on TiO2 by a sol-gel spin-coating method as the photoanodes of dye sensitized solar cells (DSSCs). A comparative study with different structures including TiO2, TiO2/NiO and TiO2/NiO:Eu(3+),Tb(3+) as the photoanodes was carried out to illustrate the photovoltaic performance of solar cells. NiO could enhance the performance of DSSCs ascribed to acting as a barrier for the charge recombination from the fluorine doped tin oxide (FTO) to electrolyte and forming a p-n junction (NiO/TiO2). Moreover, Eu(3+), Tb(3+) co-doped NiO could accelerate the electron transfer at TiO2/dye/electrolyte interface, which further benefited the performance of solar cells. The solar cells assembled with the photoelectrodes consisting of NiO:Eu(3+),Tb(3+) and TiO2 exhibited short-circuit current density (JSC) of 17.4 mA cm(-2), open-circuit voltage (VOC) of 780 mV and conversion efficiency of 8.8%, which were higher than that with TiO2/NiO and pure TiO2. The mechanisms of the influence of NiO and NiO:Eu(3+),Tb(3+) on the photovoltaic performance of DSSCs were discussed. PMID:27506930

  20. Investigation into real-time pressure sensing properties of SnO2, TiO2, and TiO2/ZnO thick films with interdigitated electrodes

    Highlights: → The pressure sensing properties of metal oxides thick film capacitors are reported. → At the applied load of 5 kPa, the response times of 2.5 s, 5.6 s and 4 s were recorded for SnO2, TiO2, and TiO2/ZnO sensors, respectively. → These pressure sensors have long-term stability and low hysteresis. → They are reusable, as their electrical properties were restored by annealing. - Abstract: The pressure sensing properties of nanocomposite SnO2, TiO2, and TiO2/ZnO thick film capacitors with interdigitated electrodes are investigated. To form the dielectric layers, the metal oxides powders were respectively mixed with isopropanol, wet ball milled for 24 h, then the mixtures were dried at 120 deg. C and further the powders were placed under 2 tonnes of pressure to form pellets, which were fired at 1250 deg. C (rate of 5 deg. C/min) in a vacuum of 6 x 10-3 mbar for 5 h, followed by cooling (rate of 3 deg. C/min). After firing, the resultant nanopowders were mixed with 7 wt.% of polyvinyl butyral (binder) and suitable amount of ethylenglycolmonobutylether (solvent) to form the pastes. These were screen-printed over the Ag electrodes on alumina substrates to form SnO2, TiO2, and TiO2/ZnO capacitor pressure sensors accordingly. The evaluation of pressure sensing properties of these sensors was performed using a HP 4192A Impedance Analyser, which recorded the changes in the values of the capacitances under different mechanical stresses. At the applied load of 5 kPa, the response times of 2.5 s, 5.6 s and 4 s were recorded for SnO2, TiO2, and TiO2/ZnO sensors, respectively. In addition to instant response times, these pressure sensors have the advantage of being reusable, as their electrical properties were restored to the original value after annealing for 2 h at 80 deg. C. Moreover, one year later after the initial testing, the sensors were still operational and produced similar time responses to pressure.