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Sample records for tio2 thin films

  1. TiO2 thin films for dyes photodegradation

    International Nuclear Information System (INIS)

    The aim of the present study is to investigate the influence of the TiO2 specific surface (powder, film) on the photocatalytic degradation of methyl orange. Porous TiO2 films were deposited on transparent conducting oxide substrates by spray pyrolysis deposition. The films were characterized by X-ray diffraction (XRD), Scanning Electronic Microscopy, and the UV-Vis spectroscopy. The XRD spectra of nanoporous TiO2 films revealed an anatase, crystalline structure that is known as the most suitable structure in photocatalysis. The average thickness of the films was 260 nm and the measured band gap is 3.44 eV. The influence of the operational parameters (dye concentration, contact time) on the degradation rate of the dye on TiO2 was examined. There were calculated the kinetic parameters and the process efficiency. Using thin films of TiO2 is technologically recommended but raises problems due to lowering the amount of catalyst available for the dye degradation

  2. Superhydrophilicity of TiO2 nano thin films

    International Nuclear Information System (INIS)

    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 superhydrophilic surface rather than glass and polycrystalline Si substrates. Our results are consistent with the idea that UV-induced wetting of TiO2 surface is caused by the removal of hydrophobic layers of hydrocarbons by TiO2-mediated photo-oxidation, which leads to the attractive interaction of water with clean TiO2 surface. (authors)

  3. Electrochemical Behavior of TiO2 Nanoparticle Doped WO3 Thin Films

    OpenAIRE

    Suvarna R. Bathe; Mr. P.S.Patil

    2014-01-01

    Nanoparticle TiO2 doped WO3 thin films by pulsed spray pyrolysis technique have been studied on fluorine tin doped (FTO) and glass substrate. XRD shows amorphous nature for undoped and anatase phase of TiO2 having (101) plane for nanoparticle TiO2 doped WO3 thin film. SEM shows microfibrous reticulated porous network for WO3 with 600 nm fiber diameter and nanocrystalline having size 40 nm for TiO2 nanoparticle doped WO3 thin film. TiO2 nanoparticle doped WO3 thin film shows ~95% reversibility...

  4. Preparation of anatase TiO2 thin films by vacuum arc plasma evaporation

    International Nuclear Information System (INIS)

    Anatase titanium dioxide (TiO2) thin films with high photocatalytic activity have been prepared with deposition rates as high as 16 nm/min by a newly developed vacuum arc plasma evaporation (VAPE) method using sintered TiO2 pellets as the source material. Highly transparent TiO2 thin films prepared at substrate temperatures from room temperature to 400 deg. C exhibited photocatalytic activity, regardless whether oxygen (O2) gas was introduced during the VAPE deposition. The highest photocatalytic activity and photo-induced hydrophilicity were obtained in anatase TiO2 thin films prepared at 300 deg. C, which correlated to the best crystallinity of the films, as evidenced from X-ray diffraction. In addition, a transparent and conductive anatase TiO2 thin film with a resistivity of 2.6 x 10-1 ? cm was prepared at a substrate temperature of 400 deg. C without the introduction of O2 gas

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

    OpenAIRE

    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 ...

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

    International Nuclear Information System (INIS)

    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

  7. Enhanced photoelectrochemical and photocatalytic activity of WO3-surface modified TiO2 thin film

    OpenAIRE

    Qamar, Mohammad; Drmosh, Qasem; Ahmed, Muhammad I; Qamaruddin, Muhammad; Yamani, Zain H.

    2015-01-01

    Development of nanostructured photocatalysts for harnessing solar energy in energy-efficient and environmentally benign way remains an important area of research. Pure and WO3-surface modified thin films of TiO2 were prepared by magnetron sputtering on indium tin oxide glass, and photoelectrochemical and photocatalytic activities of these films were studied. TiO2 particles were

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

    Indian Academy of Sciences (India)

    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.

  9. PHOTOCATALYTIC PROPERTIES OF Cr DOPED TiO2SiO2 NANOSTRUCTURE THIN FILM

    Directory of Open Access Journals (Sweden)

    Akbar Eshaghi

    2012-07-01

    Full Text Available Cr doped TiO2SiO2 nanostructure thin film on glass substrates was prepared by a sol-gel dip coating method. X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS and UV-vis spectrophotometer were used to characterize the structural, chemical and optical properties of the thin film. The XRD showed that thin films contain only anatase phase. FE-SEM images illustrated that anatase average crystallite size in the pure TiO2 and Cr doped TiO2SiO2 thin films are 15 nm and 10 nm, respectively. XPS spectra confirmed the presence of Cr3+ in the thin film. UV-vis absorption spectra indicated that absorption edge in Cr doped TiO2SiO2 thin film shifted to the visible light region. The photocatalytic results pointed that Cr doping in TiO2SiO2 improved decoloring rate of methyl orange in comparison to pure TiO2 thin film.

  10. Biocompatibility and Surface Properties of TiO2 Thin Films Deposited by DC Magnetron Sputtering

    Directory of Open Access Journals (Sweden)

    Francisco López-Huerta

    2014-05-01

    Full Text Available We present the study of the biocompatibility and surface properties of titanium dioxide (TiO2 thin films deposited by direct current magnetron sputtering. These films are deposited on a quartz substrate at room temperature and annealed with different temperatures (100, 300, 500, 800 and 1100 °C. The biocompatibility of the TiO2 thin films is analyzed using primary cultures of dorsal root ganglion (DRG of Wistar rats, whose neurons are incubated on the TiO2 thin films and on a control substrate during 18 to 24 h. These neurons are activated by electrical stimuli and its ionic currents and action potential activity recorded. Through X-ray diffraction (XRD, the surface of TiO2 thin films showed a good quality, homogeneity and roughness. The XRD results showed the anatase to rutile phase transition in TiO2 thin films at temperatures between 500 and 1100 °C. This phase had a grain size from 15 to 38 nm, which allowed a suitable structural and crystal phase stability of the TiO2 thin films for low and high temperature. The biocompatibility experiments of these films indicated that they were appropriated for culture of living neurons which displayed normal electrical behavior.

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

    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

  13. Buckle delamination of textured TiO2 thin films on mica

    International Nuclear Information System (INIS)

    We present the growth of textured TiO2 thin films on muscovite mica using pulsed laser deposition. Atomic force microscopy, scanning electron microscopy, X-ray photoemission spectroscopy, and transmission electron microscopy were used to characterize the TiO2 films. Quasi-periodic wavy and comb-like buckles were observed. Below a critical thickness of about 25 nm, TiO2 films were relatively smooth, and buckles began to form when the nominal thickness of TiO2 films was larger than 25 nm. Co-existence of wavy and comb-like quasi-periodic buckles was observed when the nominal thickness of TiO2 films was larger than 100 nm. The film stress is compressive due to the competition of the tensile stress from the lattice mismatch and the growth stress. The buckle delamination occurred when the compressive stress overcome the adhesion strength of the TiO2 films on mica. A value of adhesion strength around 0.9 MPa for TiO2 on mica is obtained. The symmetric domains of buckles are assigned to the anisotropic lattice mismatch for TiO2 on mica

  14. Temperature dependence of gas sensing behaviour of TiO2 doped PANI composite thin films

    International Nuclear Information System (INIS)

    In the present work we have reported the effect of temperature on the gas sensing properties of TiO2 doped PANI composite thin film based chemiresistor type gas sensors for hydrogen gas sensing application. PANI and TiO2 doped PANI composite were synthesized by in situ chemical oxidative polymerization of aniline at low temperature. The electrical properties of these composite thin films were characterized by I-V measurements as function of temperature. The I-V measurement revealed that conductivity of composite thin films increased as the temperature increased. The changes in resistance of the composite thin film sensor were utilized for detection of hydrogen gas. It was observed that at room temperature TiO2 doped PANI composite sensor shows higher response value and showed unstable behavior as the temperature increased. The surface morphology of these composite thin films has also been characterized by scanning electron microscopy (SEM) measurement

  15. Sub-band-gap photoresponse of TiO2-x thin-film-electrolyte interface

    Science.gov (United States)

    Kim, Wha-Tek; Kim, Chang-Dae; Choi, Q. Won

    1984-10-01

    When a TiO2-x thin-film-electrolyte interface is illuminated by the monochromatic light in the sub-band-gap region, broad photocurrent peaks are observed at 462, 515, 1050, and 1258 nm. The energies of these peaks are in good agreement with the energies of defect levels of the TiO2 single crystal due to oxygen vacancies. From these experimental results, the photoresponse of the TiO2-x thin-film-electrolyte interface in the sub-band-gap region is interpreted as arising from electronic excitations between the trap levels which originate from the defects of the TiO2-x thin film and the conduction band.

  16. Controlling the particle size of nanobrookite TiO2 thin films

    International Nuclear Information System (INIS)

    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).

  17. Magneto-optical Kerr rotation in amorphous TiO2/Co magnetic semiconductor thin films

    International Nuclear Information System (INIS)

    TiO2/Co thin films were prepared on glass substrates under thermal non-equilibrium condition by alternately sputtering very thin TiO2 and Co layers for 60 periods. Microstructure and composition analyses by X-ray diffraction, transmission electron microscopy, X-ray photoemission spectroscopy and electron energy-loss spectroscopy indicated that the Co element was incorporated into TiO2 to form the Ti1-x Co x O2 magnetic semiconductors. The obvious Kerr rotations in the samples were observed, and the relation between the Kerr rotation and Co concentration was discussed

  18. Obtention of TiO2 thin films by laser ablation

    International Nuclear Information System (INIS)

    The thin films of TiO2 have been investigated extensively in the last years, since they have a broad variety of applications, which owing to their less usual chemical, electrical and optical properties. In this work are presented the obtained results to deposit TiO2 thin films over glass substrates utilizing the Laser ablation technique. It has been deposited thin films at different substrate temperatures and different oxygen pressures, with the purpose to study the influence of these deposit parameters in the structural characteristics of the obtained films. The structural characterization was realized through Raman spectroscopy and X-ray diffraction (XRD), the superficial morphology was verified by Scanning Electron Microscopy (SEM). The results show that the obtained films were TiO2 in rutile phase, getting this with the substrates at low temperature, its morphology shows a soft surface with some sprinkling particles and a good adherence. (Author)

  19. Preparation and Photocatalytic Activity of TiO2 Thin Films on Al Alloys

    Directory of Open Access Journals (Sweden)

    CAI Qian, WANG Jin-Shu, LI Hong-Yi, LIU Shao-Lin, LI Yu-Mei

    2012-06-01

    Full Text Available Using anodized 6061 aluminum alloy and pure aluminum as the templates, TiO2 thin films were prepared through a liquid deposition method. The TiO2 thin film fabricated on the 6061 aluminum alloy substrates appears as bamboo―like structures with holes, whereas that prepared on anodized pure aluminum substrate has one―dimensional tubular structures. The main reason is that magnesium in aluminum alloy is oxidized to form magnesium oxide which has a lower volume than that of Al2O3. The photocatalytic ability of the TiO2 films prepared on the aluminum alloy is superior to that of the films fabricated on the pure aluminum. TiO2 prepared on aluminum alloy has higher specific surface area due to its bamboo―like structures with holes, leading to better performance in the degradation of methylene blue. The photocatalytic performance of the TiO2 by the degradation of aqueous methylene blue is in accordance with the first kinetic equation. TiO2 films deposited in 0.1 mol/L (NH4) TiF6 solution obtain the best photocatalytic performance at apparent reaction rate of 0.00444/min.

  20. Deposition of TiO2 thin films using atmospheric dielectric barrier discharge

    International Nuclear Information System (INIS)

    In this paper the influence of precursor (titanium tetraisopropoxide (TTIP)) temperature, precursor and gas flow rates on the surface properties of TiO2 thin films deposited by atmospheric dielectric barrier discharge (ADBD) chemical vapour deposition (CVD) were investigated. Argon was used as working gas. Influence of O2 used as oxidizer was evaluated for determination of hydrophilicity of the films. Surface morphology of the thin TiO2 films deposited on glass substrates was studied by the atomic force microscopy (AFM) and water contact angle (CA) measurement. CA tests proved wettability improvement in experiments with oxygen addition

  1. Structural, optical, photoluminescence and photocatalytic investigations on Fe doped Tio2 thin films

    International Nuclear Information System (INIS)

    Pure and Fe doped TiO2 thin films were deposited onto quartz substrates maintained at room temperature by radio frequency magnetron sputtering. The films were annealed at 873 K in air for 2 h and characterized using X-ray diffraction (XRD), micro Raman spectroscopy, Scanning electron microscopy (SEM), Energy dispersive spectroscopy, ultraviolet-visible and photoluminescence (PL) spectroscopy. Pure TiO2 thin films were XRD-amorphous, but micro Raman spectra revealed the presence of anatase phase. Doping with Fe has influenced the transformation of films to anatase phase. Improved crystallinity was observed in the 0.1 at% Fe doped films, where the lattice constants approached the values for bulk anatase TiO2, and the films showed minimum strain. At higher Fe concentrations, micro Raman spectra revealed the presence of rutile phase also. SEM images revealed crack free surface and surface roughness was found to increase with increase in Fe concentration. Doping with Fe has resulted in a red shift of absorption edge. PL emission intensity was found to increase with Fe concentration, but at higher concentrations quenching of PL emission was observed. Fe doping resulted in enhancement of photocatalytic activity, evaluated by monitoring the degradation of methylene blue solution. 0.8 at% Fe doped TiO2 films exhibited the highest photocatalytic activity. - Highlights: • Use of RF magnetron sputtering for obtaining high quality TiO2 thin films • Extending wavelength sensitizing range of TiO2 thin films by Fe doping • Creation of short range crystalline order in films by optimal Fe doping • Enhanced photocatalytic activity of films possessing short range order

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

    Science.gov (United States)

    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

    International Nuclear Information System (INIS)

    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 of titanium dioxide (Tio2) thin films by sol.gel dip coating method

    International Nuclear Information System (INIS)

    Titanium dioxide (TiO2) thin films have been receiving much attention in the past as their chemical stability, high refractive index, and high dielectric constant [1], allow their use as components in optoelectronic devices, sensors, photo catalysis [2], solar cells [3], and wave guides [4]. Titanium dioxide thin films have been prepared from tetra-butylorthotitanium solution and buthanol as a solvent by sol.gel dip-coating method on an ITO substrate. The samples obtained were characterized by different experimental techniques: X-ray diffraction; Raman spectroscopy; scanning electron microscopy (SEM), optical microscopy, Photoluminescence, infrared and ultraviolet spectroscopy. The X-ray diffraction (XRD) results showed that TiO2 thin film at 300 degree C was amorphous, and transformed into the anatase.brookite at 400 degree C, the crystallite size of TiO2 thin films was increased with increasing temperature gives sizes in the range 5 to 25 nm. The observed by scanning electron microscope (SEM) shows that the coating was transparent and homogeneous without any visual cracking over a wide area, and multiple coating increased thickness, but did not affect the uniformity of the film. The film thickness varies, depending on the number of dipping iterations, between 20 (1 layer) and 153.6 nm (4 layers). The refractive index increases with increasing temperature, and the porosity of TiO2 thin films, however, shows the opposite trend

  5. Photocatalytic activities of Ion doped TiO2 thin films when prepared on different substrates

    International Nuclear Information System (INIS)

    Pure and ion doped TiO2 thin films were prepared by sol-gel dip coating process on metallic and non-metallic substrates. Test metal ion concentration ranged from 0.000002 to 0.4 at.%. The resulting films were annealed in air and characterized by optical spectroscopy and X-ray diffraction. The photodegradation of methyl orange under UV irradiation by pristine and ion-doped TiO2 films was quantified in a photocatalytic reactor developed in this study. In general, both doped and undoped TiO2 crystals appeared in anatase phase and the photocatalytic activities of the TiO2 thin films varied with substrates, calcination temperature, doping ions and their concentrations. The best calcination temperature for different substrates ranged from 450 to 580 oC. Films prepared on the metallic substrates resulted in higher photocatalytic activities, while ion doping lowered their efficiencies. On the contrary, for non-metallic substrates except ceramic the photocatalytic efficiencies of undoped films were much lower (3+ with the tile substrate. Overall, ion doping affected the photocatalytic efficiency of TiO2 films, and an optimal doping concentration of between 0.0002 and 0.002 at.%, close to an estimate by the Debye length equation, resulted in the highest efficiency for most substrates.

  6. Optical spectra of graded nanostructured TiO 2 chiral sculptured thin films

    Science.gov (United States)

    Babaei, F.; Esfandiar, A.; Savaloni, H.

    2010-07-01

    The optical properties of graded chiral sculptured TiO 2 thin films in axial and non-axial excited states are calculated using the rigorous coupled wave analysis method (RCWA) in conjunction with the Bruggeman homogenization formalism. The filtering frequency and polarization selectivity of these graded nanostructured TiO 2 sculptured thin films showed dependence on both structural and deposition parameters. The results achieved are consistent with the experimental data [K. M. Krause and M. J. Bret, Adv. Funct. Mater. 18 (2008) 3111].

  7. Chromium doped TiO2 sputtered thin films synthesis, physical investigations and applications

    CERN Document Server

    Hajjaji, Anouar; Gaidi, Mounir; Bessais, Brahim; El Khakani, My Ali

    2014-01-01

    This book presents co-sputtered processes ways to produce chrome doped TiO2 thin films onto various substrates such as quartz, silicon and porous silicon. Emphasis is given on the link between the experimental preparation and physical characterization in terms of Cr content. Moreover, the structural, optical and optoelectronic investigations are emphasized throughout. The book explores the potencial applications of devices based on Cr doped TiO2 thin films as gas sensors and in photocatalysis and in the photovoltaic industry. Also, this book provides extensive leads into research literature,

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

    Science.gov (United States)

    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

  9. Photocatalytic activity of dc magnetron sputter deposited amorphous TiO2 thin films

    International Nuclear Information System (INIS)

    For photocatalytic thin film applications TiO2 is one of the most important materials. The most studied TiO2 crystal phase is anatase, though also rutile and brookite show good photoactivity. Usually anatase or a mixture of rutile and anatase is applied for powder or thin film catalysts. It has been claimed that amorphous films do not exhibit any or only a very low photocatalytic activity. We have deposited amorphous thin films by dc magnetron sputtering from sub-stoichiometric TiO2-x targets. The coatings are transparent and show a photocatalytic activity half of that of a thin layer of spin-coated reference photocatalyst powder. Annealing the thin films to yield anatase crystallization more than doubles their photocatalytic activity. At the same film thickness these thin films show the same activity as a commercially available photocatalytic coating. The dependence of the photocatalytic activity on deposition parameters like gas pressure and sputter power is discussed. A decrease in film density, as deduced from the refractive index and the microstructure, resulted in an increase in photocatalytic activity. Film thickness has a marked influence on the photocatalytic activity, showing a strong increase up to 300-400 nm, followed by a much shallower slope

  10. Micro-structuring of TiO 2 thin films by laser-assisted diffraction processing

    Science.gov (United States)

    Van Overschelde, O.; Guisbiers, G.; Wautelet, M.

    2007-07-01

    Thin films of TiO 2 are deposited by magnetron sputtering on glass substrate and are irradiated by UV radiation using a KrF excimer laser (248 nm). These thin films are patterned with a razor blade placed on the way of the radiation just in front of the TiO 2 thin film. Just near the edge of the razor blade on the thin film, diffraction lines are observed, resulting in the ablation of the film. These patterns are characterized by optical microscopy, mechanical profilometry. Diffraction up to the 35th order is observed. The results are shown to be compatible with a model in which electronic excitation plays the major role.

  11. Comparison of photovoltaic performance of TiO2 nanoparticles based thin films via different routes

    Science.gov (United States)

    Ji, Yajun

    2015-11-01

    Well crystallized TiO2 nanoparticles were prepared by hydrothermal and sol-gel routes, respectively. The morphologies, structures, crystallinity and optical properties of resulted TiO2 nanoparticles-based thin films via the two methods were examined by field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), X-ray diffractometer (XRD) and reflectance spectra. In addition, comparison of photovoltaic performance of TiO2 nanoparticles-based thin films by the two methods was performed. It is found that the maximum energy conversion efficiency of 4.06% was achieved based on the obtained electrode via hydrothermal, which is much better than that of the sol-gels route. The uniform film structure with improved dye absorption capability, increased diffused reflectance property and relatively low charge recombination rates for injected electrons are believed to be responsible to the superior photoelectrochemical properties of dye-sensitized solar cells (DSSC) via hydrothermal route.

  12. Rutile TiO2 thin films grown by reactive high power impulse magnetron sputtering

    International Nuclear Information System (INIS)

    Thin TiO2 films were grown on Si(001) substrates by reactive dc magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS) at temperatures ranging from 300 to 700 °C. Optical and structural properties of films were compared both before and after post-annealing using scanning electron microscopy, low angle X-ray reflection (XRR), grazing incidence X-ray diffractometry and spectroscopic ellipsometry. Both dcMS- and HiPIMS-grown films reveal polycrystalline rutile TiO2, even prior to post-annealing. The HiPIMS-grown films exhibit significantly larger grains compared to that of dcMC-grown films, approaching 100% of the film thickness for films grown at 700 °C. In addition, the XRR surface roughness of HiPIMS-grown films was significantly lower than that of dcMS-grown films over the whole temperature range 300–700 °C. Dispersion curves could only be obtained for the HiPIMS-grown films, which were shown to have a refractive index in the range of 2.7–2.85 at 500 nm. The results show that thin, rutile TiO2 films, with high refractive index, can be obtained by HiPIMS at relatively low growth temperatures, without post-annealing. Furthermore, these films are smoother and show better optical characteristics than their dcMS-grown counterparts. - Highlights: • We demonstrate growth of rutile TiO2 on Si (111) by high power impulse magnetron sputtering. • The films exhibit significantly larger grains than dc magnetron sputtered films • TiO2 films with high refractive index are obtained without post-growth annealing

  13. Mn-doped TiO2 thin films with significantly improved optical and electrical properties

    Science.gov (United States)

    Lu, Liu; Xia, Xiaohong; Luo, J. K.; Shao, G.

    2012-12-01

    TiO2 thin films with various Mn doping contents were fabricated by reactive magnetron sputtering deposition at 550 °C and their structural, optical and electrical properties were characterized. All films were made of densely packed columnar grains with a fibrous texture along the normal direction of the substrate. The as-deposited structure in the pure TiO2 film consisted of anatase grains with the [1 0 1] texture. Mn incorporation stabilized the rutile phase and induced lattice contraction in the [1 0 0] direction. The texture in the Mn-doped films changed from [1 1 0] to [2 0 0] with increasing Mn content. The incorporation of Mn in the TiO2 lattice introduced intermediate bands into its narrowed forbidden gap, leading to remarkable red-shifts in the optical absorption edges, together with significantly improved electrical conductivity of the thin films. Hall measurement showed that the incorporation of Mn-induced p-type conductivity, with hole mobility in heavily doped TiO2 (˜40% Mn) being about an order higher than electron mobility in single-crystal rutile TiO2. Oxygen vacancies, on the other hand, interacted with substitutional Mn atoms to reduce its effect on optical and electrical properties.

  14. Superhydrophilic TiO2 thin film by nanometer scale surface roughness and dangling bonds

    Science.gov (United States)

    Bharti, Bandna; Kumar, Santosh; Kumar, Rajesh

    2016-02-01

    A remarkable enhancement in the hydrophilic nature of titanium dioxide (TiO2) films is obtained by surface modification in DC-glow discharge plasma. Thin transparent TiO2 films were coated on glass substrate by sol-gel dip coating method, and exposed in DC-glow discharge plasma. The plasma exposed TiO2 film exhibited a significant change in its wetting property contact angle, which is a representative of wetting property, has reduced to considerable limits 3.02° and 1.85° from its initial value 54.40° and 48.82° for deionized water and ethylene glycol, respectively. It is elucidated that the hydrophilic property of plasma exposed TiO2 films dependent mainly upon nanometer scale surface roughness. Variation, from 4.6 nm to 19.8 nm, in the film surface roughness with exposure time was observed by atomic force microscopy (AFM). Analysis of variation in the values of contact angle and surface roughness with increasing plasma exposure time reveal that the surface roughness is the main factor which makes the modified TiO2 film superhydrophilic. However, a contribution of change in the surface states, to the hydrophilic property, is also observed for small values of the plasma exposure time. Based upon nanometer scale surface roughness and dangling bonds, a variation in the surface energy of TiO2 film from 49.38 to 88.92 mJ/m2 is also observed. X-ray photoelectron spectroscopy (XPS) results show change in the surface states of titanium and oxygen. The observed antifogging properties are the direct results of the development of the superhydrophilic wetting characteristics to TiO2 films.

  15. Fabrication of TiO2 nanotubes by anodization of Ti thin films for VOC sensing

    International Nuclear Information System (INIS)

    Ti thin films were anodized in aqueous HF (0.5 wt.%) and in polar organic (0.5 wt.% NH4F + ethylene glycol) electrolytes to form TiO2 nanotube arrays. Ti thin films were deposited on microscope glass substrates and then anodized. Anodization was performed at potentials ranging from 5 V to 20 V for the aqueous HF and from 20 V to 60 V for the polar organic electrolytes over the temperatures range from 0 to 20 °C. The TiO2 nanotubes were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX). It has been observed that anodization of the deposited Ti thin films with aqueous HF solution at 0 °C resulted in nanotube-type structures with diameters in the range of 30–80 nm for an applied voltage of 10 V. In addition, the nanotube-type structure is observed for polar organic electrolyte at room temperature at the anodization voltage higher than 40 V. The volatile organic compound (VOC) sensing properties of TiO2 nanotubes fabricated using different electrolytes were investigated at 200 °C. The maximum sensor response is obtained for carbon tetrachloride. The sensor response is dependent on porosity of TiO2. The highest sensor response is observed for TiO2 nanotubes which are synthesized using aqueous HF electrolyte and have very high porosity.

  16. TiO2 Thin Film via Sol-Gel Method: Investigation on Molarity Effect

    Science.gov (United States)

    Mohamad Saad, Puteri Sarah; Sutan, Hanis Binti; Sobihana Shariffudin, Shafinaz; Hashim, Hashimah; Mohd Noor, Uzer

    2015-11-01

    We have systematically investigated the current-voltage (I-V), absorbance and optical band gap of TiO2 thin film prepared through varying the molarity of the TiO2 precursor by sol-gel spin coating technique. In addition to the electrical and optical characteristics, the surface morphology was examined by using Atomic Force Microscope (AFM). From the image of the AFM, we were able to observe the uniformity of the TiO2 thin film. From the experimental results, we found that the uniformity of the TiO2 thin film is optimized at 0.2M sample. It is also found that, as the molarity increased, there is tendency of the resistivity to decrease. Not only that, the absorbance measurement and optical band gap also gave its best value for 0.2M sample. Therefore, in this work it is concluded that 0.20M of TiO2 gave the best characteristics for all measurements.

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

    DEFF Research Database (Denmark)

    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....

  18. Influence of reactive sputtering process parameters on the structure and properties of TiO 2 thin films

    OpenAIRE

    El-Hamshary, Azza Amin

    2011-01-01

    Recently, titanium dioxide (TiO2) thin films have attracted significant attention and became a major area of research since the discovery of its photocatalytic effect on water. TiO2 is characterized by high chemical stability, mechanical hardness and optical transmittance as well as by a high refractive index. Therefore it is used in a variety of applications including solar energy conversion, optical coatings and protective layers. TiO2 thin films can crystallize in two crystalline structure...

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

    Science.gov (United States)

    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

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

    International Nuclear Information System (INIS)

    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)

  1. Effect of Au Nanoparticles Doping on The Properties of TiO2 Thin Films

    Directory of Open Access Journals (Sweden)

    Aytaç GÜLTEKİN

    2014-02-01

    Full Text Available In this study, pure and gold (Au nanoparticles doped TiO2 thin films (Au/Ti = 10, 20, 30, 40 and 50 at% were prepared by sol-gel method and the impact of Au nanoparticles doping on the optical, structural and morphological properties of these thin films was examined. All thin films were characterized using ultraviolet-visible-near infrared (UV-Vis-NIR spectrophotometry, X-ray diffraction (XRD, transmission electron microscopy (TEM and atomic force microscopy (AFM. The optical band gap of the thin films increases from 3.74 eV to 3.89 eV with the increase of Au nanoparticles concentrations due to the Moss-Burstein effect. XRD results show that all thin films have cubic poly-crystal structure and the intensities of peaks of the crystalline phase increased with the increase of Au nanoparticles concentrations. The AFM results indicate that the TiO2 thin films are formed from the nanoparticles and the grain size of the films is changed with Au doping level. Consequently, it is shown that the structural, morphological and optical properties of the TiO2 thin films could be changed by Au nanoparticles-doping. DOI: http://dx.doi.org/10.5755/j01.ms.20.1.3709

  2. Optical Spectra of Graded Nanostructured TiO2 Chiral Thin Films

    CERN Document Server

    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.

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

    Science.gov (United States)

    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

  4. Magnetic and structural study of Cu-doped TiO2 thin films

    CERN Document Server

    Torres, C E R; Cabrera, A F; Errico, L A; Navarro, A M M; Renter'ia, M; S'anchez, F H; Duhalde, S

    2007-01-01

    Transparent pure and Cu-doped (2.5, 5 and 10 at. %) anatase TiO2 thin films were grown by pulsed laser deposition technique on LaAlO3 substrates. The samples were structurally characterized by X-ray absorption spectroscopy and X-ray diffraction. The magnetic properties were measured using a SQUID. All films have a FM-like behaviour. In the case of the Cu-doped samples, the magnetic cycles are almost independent of the Cu concentration. Cu atoms are forming CuO and/or substituting Ti in TiO2. The thermal treatment in air promotes the CuO segregation. Since CuO is antiferromagnetic, the magnetic signals present in the films could be assigned to this Cu substitutionally replacing cations in TiO2.

  5. Magnetic and structural study of Cu-doped TiO2 thin films

    International Nuclear Information System (INIS)

    Transparent pure and Cu-doped (2.5, 5 and 10 at.%) anatase TiO2 thin films were grown by pulsed laser deposition technique on LaAlO3 substrates. The samples were structurally characterized by X-ray absorption spectroscopy and X-ray diffraction. The magnetic properties were measured using a SQUID. All films have a FM-like behaviour. In the case of the Cu-doped samples, the magnetic cycles are almost independent of the Cu concentration. Cu atoms are forming CuO and/or substituting Ti in TiO2. The thermal treatment in air promotes the CuO segregation. Since CuO is antiferromagnetic, the magnetic signals present in the films could be assigned to Cu substitutionally replacing cations in TiO2

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

    International Nuclear Information System (INIS)

    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.

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

    OpenAIRE

    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 ...

  8. The Photocatalytic and Antibacterial Activity of Cu-Doped TiO2 Thin Films

    Directory of Open Access Journals (Sweden)

    Weerachai SANGCHAY

    2013-02-01

    Full Text Available Thin films of TiO2 and TiO2 doped with Cu were prepared by sol-gel method. The prepared films were calcined at the temperature of 400 C for 2 h with the heating rate of 10 C/min. Physical properties as well as crystal compositions of the fabricated films were characterized by XRD, EDX SEM and AFM techniques. The results show that all samples have thickness range from 0.25 to 1.0 um. The film surfaces are typically uniform and dense with TiO2 nanoparticles. The photocatalytic activities of the thin films were also tested via the degradation of methylene blue (MB solution under UV irradiation. Finally, antibacterial activity efficiency was evaluated by the inactivation of E.coli. It was observed that higher Cu concentration gives better photocatalytic activity. With the highest dopant concentration investigated in this experiment (TiO2-1.0Cu condition the films show photocatalytic of 70 % and antibacterial activity of 100 %.

  9. Reactive direct current magnetron sputtered TiO2 thin films with amorphous to crystalline structures

    International Nuclear Information System (INIS)

    TiO2 thin films were deposited on soda-lime glass substrates by reactive direct current magnetron sputtering in a mixture of pure argon and oxygen. The influence of both the deposition time, td, and the post-annealing treatments on the films morphology, composition and structure was analyzed by scanning electron microscopy, ellipsometry, X-ray photoelectrons spectroscopy, X-ray diffraction (XRD) and Raman spectroscopy. Amorphous TiO2 was obtained for the shortest deposition time, td = 15 min. Increasing td up to 30 min, poorly crystallized anatase and rutile phases were formed together with amorphous TiO2, as was revealed by complementary XRD patterns and Raman spectra. For longer td, the growth of the anatase phase dominates that of the rutile phase. The post-annealing treatment of the films in air at 450 oC. induced the complete crystallization of the films leading to mainly anatase films for all the deposition times. All these results show the feasibility to fabricate stoichiometric TiO2 thin films with amorphous to crystalline structures by means of soft fabrication conditions: low substrate temperature and moderate annealing treatment

  10. Photocatalytic Separate Evolution of Hydrogen and Oxygen over Highly Ordered Nanorods and Bulk TiO2 Thin Films

    OpenAIRE

    Chao-Wei Huang; Chi-Hung Liao; Jeffrey C. S. Wu

    2013-01-01

    Three types of photocatalytic TiO2 thin films with different structures, nanorods (NR-TiO2), mesoporous (MP-TiO2), and bulk structure (BK-TiO2), were prepared by evaporation induced self-assembling process or electron beam induced deposition method. The post-calcination treatment at 400oC was performed for all TiO2 thin films to induce their crystallinity. The TiO2 structure on the film properties were studied by material characterizations. The photoelectrochemical characteristics of the TiO2...

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

    International Nuclear Information System (INIS)

    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.

  12. Photoluminescence study of carbon doped and hydrogen co-doped TiO2 thin films

    International Nuclear Information System (INIS)

    Photoluminescence (PL) spectroscopy was used to study the charge carrier recombination processes in the C-doped and H-co-doped TiO2 thin films produced by magnetron sputtering. The radiative recombinations evident from the PL emission spectra (at about 470 nm, 600 nm and 850 nm) were associated primarily with defects intrinsic to most thin films. Doping with C was found to promote the non-radiative recombination of charge carriers. This was due the filling of the band gap with C-induced energy states, as well as defect-rich microstructure formed also a result of C doping. This effect of C doping is lost upon annealing which eliminates the C dopant from of the thin films. Doping with H on the other hand permanently modifies the band gap structure of rutile by introducing a luminescence centre/s emitting at about 600 nm, while suppressing the less desirable centre in the middle of the rutile band gap responsible for the characteristic PL at 850 nm. - Highlights: • The photoluminescence emissions from C doped TiO2 originate from intrinsic TiO2 defects. • Doping of TiO2 with C promotes the non-radiative recombination of charge carriers. • Doping with H eliminates the undesirable deep energy centre in the rutile band gap

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

    Science.gov (United States)

    Rafieian, Damon; Ogieglo, Wojciech; Savenije, Tom; Lammertink, Rob G. H.

    2015-09-01

    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 (TiOxtransformation. 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.

  14. Structural Analysis of RF Sputtered TiO2 Thin Film on Cu Substrate for Various Annealing Temperatures

    Directory of Open Access Journals (Sweden)

    Shanmugan S

    2014-08-01

    Full Text Available The structural parameters of RF sputtered TiO2 thin film deposited on Cu substrates was tested using XRD spectra. Prepared TiO2 thin film was polycrystalline nature with the mixture of cubic, orthorhombic and tetragonal phases. Orthorhombic phase was preferentially grown on Cu substrate. The crystallite size of the TiO2 thin film was varied depends on the orientations and overall decreased crystallite size was noticed upto 300 °C. The observed residual stress was compressive nature as dominated at all temperature other than 400°C. Crystal defects such as dislocation density was high for cubic phase of TiO2 at higher annealing temperature. Overall, the annealing temperatures influenced the structural parameters with respect to the observed orientations of TiO2 thin film on Cu substrates.

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

    International Nuclear Information System (INIS)

    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. Self-assembly of ordered mesoporous TiO2 thin films as photoanodes for cathodic protection of stainless steel

    International Nuclear Information System (INIS)

    Highlights: ? The ordered mesoporous TiO2 thin films were prepared on FTO substrates. ? The more effective photocathodic protection was observed for mesoporous TiO2 films. ? More negative photopotential was observed for 500 C-calcined mesoporous TiO2 film. ? The larger photocurrent was observed for mesoporous TiO2 film calcined at 500 C. - Abstract: In this paper, the ordered mesoporous TiO2 thin films that served as photoanodes for cathodic protection of SUS304 stainless steel (304SS) were prepared through the solgel and evaporation-induced self-assembly method. The as-prepared TiO2 thin films were calcined at 350 C and 500 C, and then characterized by scanning electron microscopy (SEM), the small-angle X-ray diffraction (SAXD) as well as the wide-angle X-ray powder diffraction (WAXD). Moreover, the photoelectrochemical properties of the mesoporous TiO2 thin films such as the open circuit potential (OCP), the photocurrent spectra as well as the Tafel polarization curves were also measured. The results showed that the more negative photopotential was observed for the mesoporous TiO2 films compared to the TiO2 films without mesoporous structures. Besides, the mesoporous TiO2 films calcined at 500 C exhibited the more negative photopotential and larger photocurrent than that calcined at 350 C. In conclusion, the mesoporous TiO2 films could provide the effective photogenerated cathodic protection for 304SS.

  17. Preparation of the nano structured TiO2 thin film with dip-coating method

    International Nuclear Information System (INIS)

    In this investigation, nano structured TiO2 thin films have been prepared through the Dip-coating method. The deposition solution was obtained through the hydrolysis of titanium iso-propoxide under the different range of ph. The transmission of films as an optical parameter investigated with spectrophotometer. Also the Fourier transform Infrared spectra have been used for determination of the structural phase of sample.

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

    Directory of Open Access Journals (Sweden)

    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.

  19. Synthesis, characterization and photocatalytic behavior of Ag doped TiO2 thin film

    Science.gov (United States)

    Bensouici, F.; Souier, T.; Dakhel, A. A.; Iratni, A.; Tala-Ighil, R.; Bououdina, M.

    2015-09-01

    In this study, structure, microstructure, optical properties and photocatalytic degradation of Rhodamine B (RhB) have been investigated in an aqueous heterogeneous media containing pure and Ag doped TiO2 nanostructures thin films which were prepared by a simple sol-gel route. Thermal analysis demonstrated that Ag content decreased the temperature of anatase-to-rutile phase transformation. X-ray diffraction analysis confirmed that the prepared nanostructures crystallize within anatase-type structure and that the dopant Ag ions were not fully incorporated within TiO2 host lattice, meanwhile both the refractive index and optical band gap were affected by Ag concentration. The photodegradation of Rhodamine B under UV-C radiation by using pure and Ag-doped TiO2 nanostructures showed that Ag played an important role in a significant improvement of the photodegradation efficiency and that the optimum content of Ag ions was found to be 0.5% molar ratio.

  20. Diffraction-aided laser-induced microstructuring of thin TiO2 films on glass

    Science.gov (United States)

    Van Overschelde, O.; Wautelet, M.

    2006-10-01

    Thin films of TiO2 are deposited by magnetron sputtering on glass substrate and are irradiated by ultraviolet radiation using a KrF excimer laser. These thin films are patterned with a razor blade placed in the way of the radiation. When the fluence is in the 1250-1550mJ /cm2 range, a regular structure appears, with controlled ablation of the films. It is shown that above a critical local fluence, the ablated depth varies linearly with the local fluence. The proportionality factor is shown to be equal to two photons per evaporated molecule.

  1. Diffraction-aided laser-induced microstructuring of thin TiO2 films on glass

    International Nuclear Information System (INIS)

    Thin films of TiO2 are deposited by magnetron sputtering on glass substrate and are irradiated by ultraviolet radiation using a KrF excimer laser. These thin films are patterned with a razor blade placed in the way of the radiation. When the fluence is in the 1250-1550 mJ/cm2 range, a regular structure appears, with controlled ablation of the films. It is shown that above a critical local fluence, the ablated depth varies linearly with the local fluence. The proportionality factor is shown to be equal to two photons per evaporated molecule

  2. Effect of crystalline structure of TiO 2 substrates on initial growth of atomic layer deposited Ru thin films

    Science.gov (United States)

    Kim, Seong Keun; Han, Sora; Han, Jeong Hwan; Hwang, Cheol Seong

    2011-02-01

    Ru thin films were grown on polymorphic TiO2 thin film substrates at 230 and 250 C by atomic layer deposition using 2,4-(dimethylpentadienyl)(ethylcyclopentadienyl)Ru and an O2 gas. While the Ru films grown on amorphous and rutile TiO2 substrates showed a relatively long incubation cycle number of approximately 350 and 100 at 230 and 250 C, respectively, the Ru films grown on anatase TiO2 substrates exhibited a significantly shorter incubation delay which was attributed to the catalytic activity of anatase TiO2. This difference in the incubation cycle affected the surface morphology of the Ru films on different TiO2 substrates.

  3. Ferromagnetism in doped TiO2 thin films prepared by PLD

    International Nuclear Information System (INIS)

    Transition-Metal-doped TiO2 thin films, with nominal composition Ti0.9TM0.1O2-δ (TM = Mn, Fe, Co, Ni, Cu), were grown by pulsed laser deposition (PLD), in order to study the role of dopants in the origin and significance of room temperature ferromagnetism in these systems. The crystallographic structures and their magnetic properties were characterized and the experimental results are compared to ab-initio calculations previously reported. The films are ferromagnetic at room temperature in the cases of Fe, Co, Ni and even Cu impurities, but not in the case of Mn doping. Our results support the hypothesis that oxygen vacancies play a key role in the origin of magnetism in doped TiO2 films, and can explain the diversity of magnetic moments observed experimentally for films grown under different conditions

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

    Science.gov (United States)

    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.

  5. TiO2 thin films using organic liquid materials prepared by Hot-Wire CVD method

    International Nuclear Information System (INIS)

    TiO2 thin films prepared by Hot-Wire CVD method have been studied as a protecting material of transparent conducting oxide (TCO) against atomic hydrogen exposures for the fabrications of Si thin film solar cells. It was found that electrical conductivity of the films at room temperature reached a value of 0.4 S/cm. This value is 2-3 orders of magnitude higher than that of TiO2 films prepared by RF magnetron sputtering and electron-beam evaporation methods in our previous works. The conductivity improvement seems to be partly due to the enlargement of TiO2 crystallites

  6. Structure and optical properties of TiO2 thin films prepared by pulsed laser deposition

    Science.gov (United States)

    Białous, Anna; Gazda, Maria; Śliwiński, Gerard

    2013-03-01

    Thin TiO2 films prepared by pulsed laser deposition (PLD) in the O2 gas ambient using the bulk metal Ti or pressed TiO2 powder targets were characterized using spectroscopic methods. Films were deposited on SiO2 (001) and SiO2 glass substrates heated up to 300 °C. The deposition process was investigated at laser fluencies from the range of 1 - 3 J/cm2 and at oxygen pressure of 0.1 - 3.2 Pa. The μ-Raman and X-ray diffraction (XRD) spectra of the TiO2 films revealed consistently both the anatase and rutile crystalline phases and a strong dependence of the phase content ratio on target material and deposition conditions. The range of crystallite size determined from XRD bandwidths was between (2-30) nm and (6-14) nm for anatase and rutile, respectively. The film thickness values between 0.74 and 1.65 μm depending on the deposition time were obtained from the transmittance and ellipsometric measurements. Values of the band gap of 3.5-4.1 eV derived from absorption spectra were higher than that of 3.2 eV corresponding to anatase and this difference was ascribed to the relatively small size of the anatase crystallites and presence of rutile, too. The SEM images of films produced under similar conditions from Ti and TiO2 targets revealed porous structures. The highest anatase content was observed for films deposited by ablation of the TiO2 target at moderate laser fluencies below 2 J/cm2 and at oxygen pressure around 1.9 Pa.

  7. Crystallization Kinetics of Amorphous Sputtered Nb-Doped TiO2 Thin Films

    Science.gov (United States)

    Huong Hoang, Ngoc Lam; Hirose, Yasushi; Nakao, Shoichiro; Hasegawa, Tetsuya

    2011-10-01

    The crystallization kinetics of amorphous sputtered Nb-doped TiO2 (TNO) thin films during isothermal annealing was examined using in situ X-ray diffraction (XRD) measurements. A Johnson-Mehl-Avrami analysis yielded Avrami exponents in the range of 2.0 to 2.7 for TNO films with various oxygen contents, indicating that the crystallization of amorphous TNO films is essentially two-dimensional. The two-dimensional crystal growth is also confirmed by ex situ polarized-light optical microscopic observations of grains, which have much larger lateral sizes than the film thickness.

  8. Slurry components of TiO2 thin film in chemical mechanical polishing

    International Nuclear Information System (INIS)

    A chemical mechanical polishing (CMP) process was selected to smooth TiO2 thin film surface and improve the removal rate. Meanwhile, the optimal process conditions were used in TiO2 thin film CMP. The effects of silica sols concentration, slurry pH, chelating agent and active agent concentration on surface roughness and material removal rate were investigated. Our experimental results indicated that we got lower surface roughness (1.26 Å, the scanned area was 10 × 10 μm2) and higher polishing rate (65.6 nm/min), the optimal parameters were: silica sols concentration 8.0%, pH value 9.0, active agent concentration 50 mL/L, chelating agent concentration 10 mL/L, respectively. (semiconductor technology)

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

    Czech Academy of Sciences Publication Activity Database

    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

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

    International Nuclear Information System (INIS)

    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

  11. Nanoporous TiO2 thin film based conductometric H2 sensor

    International Nuclear Information System (INIS)

    Nanoporous titanium dioxide (TiO2) based conductometric sensors have been fabricated and their sensitivity to hydrogen (H2) gas has been investigated. A filtered cathodic vacuum arc (FCVA) system was used to deposit ultra-smooth Ti thin films on a transducer having patterned inter-digital gold electrodes (IDTs). Nanoporous TiO2 films were obtained by anodization of the titanium (Ti) thin films using a neutral 0.5% (wt) NH4F in ethylene glycol solution at 5 V for 1 h. After anodization, the films were annealed at 600 oC for 8 h to convert the remaining Ti into TiO2. The scanning electron microscopy (SEM) images revealed that the average diameters of the nanopores are in the range of 20 to 25 nm. The sensor was exposed to different concentrations of H2 in synthetic air at operating temperatures between 100 oC and 300 oC. The sensor responded with a highest sensitivity of 1.24 to 1% of H2 gas at 225 oC.

  12. X-ray absorption and emission spectroscopy of TiO2 thin films with modified anionic sublattice

    International Nuclear Information System (INIS)

    Crystallographic and optical properties as well as electronic structure of titanium dioxide thin films with modified anionic sublattice, i.e., non-stoichiometric, undoped and nitrogen doped thin films of TiO2−x and TiO2−x:N, were studied by means of X-ray diffraction, optical spectrophotometry, X-ray absorption and emission spectroscopy. We demonstrate that TiO2−x films undergo a gradual evolution of the crystallographic structure accompanied by the progressive change in interatomic distances with the preserved local symmetry and nearly unchanged effective 3d charge of Ti ions. At a certain degree of oxygen deficit an abrupt change in all the properties studied can be seen. Amorphisation, possible Ti precipitation and increased optical absorption over the visible range correlates well with a significantly higher 3d band occupancy derived from XES for TiO2−x. Thin films of TiO2−x:N demonstrate gradual evolution of the local structure and charge redistribution upon increased level of nitrogen doping. - Highlights: • Thin films of TiO2−x and TiO2−x:N were deposited by dc-pulsed reactive sputtering. • Studies with: XRD, optical spectrophotometry, XAS and XES measurements have been carried out. • TiO2−x shows preserved local symmetry and nearly unchanged effective 3d charge of Ti ions. • At certain degree of oxygen deficit in TiO2−x an abrupt change in all the properties studied is seen. • TiO2−x:N shows a gradual evolution of the local structure and charge from TiO2 to TiN

  13. Visible photoenhanced current-voltage characteristics of Au : TiO2 nanocomposite thin films as photoanodes

    International Nuclear Information System (INIS)

    In this investigation, the effect of annealing temperature and concentration of gold nanoparticles on the photoelectrochemical properties of sol-gel deposited Au : TiO2 nanocomposite thin films is studied. Various gold concentrations have been added to the TiO2 thin films and their properties are compared. All the deposited samples are annealed at different temperatures. The optical density spectra of the films show the formation of gold nanoparticles in the films. The optical bandgap energy of the Au : TiO2 films decreases with increasing Au concentration. The crystalline structure of the nanocomposite films is studied by x-ray diffractometry indicating the formation of gold nanocrystals in the anatase TiO2 nanocrystalline thin films. X-ray photoelectron spectroscopy reveals that the presence of gold in the metallic state and the formation of TiO2 are stoichiometric. The photoelectrochemical properties of the Au : TiO2 samples are characterized using a compartment cell containing H2SO4 and KOH as cathodic and anodic electrolytes, respectively. It is found that the addition of Au nanoparticles in TiO2 films enhances the photoresponse of the layer and the addition of gold nanocrystals with an optimum value of 5 mol% resulted in the highest photoelectrochemical activity. Moreover, the photoresponse of the samples is also enhanced with an increase in the annealing temperature.

  14. Characterization of TiO2 thin films obtained by metal-organic chemical vapour deposition

    International Nuclear Information System (INIS)

    Titanium dioxide (TiO2) thin films were grown on silicon substrate (100) by MOCVD process (chemical deposition of organometallic vapor phase). The films were grown at 400, 500, 600 and 700 ° C in a conventional horizontal equipment. Titanium tetraisopropoxide was used as source of both oxygen and titanium. Nitrogen was used as carrier and purge gas. X-ray diffraction technique was used for the characterization of the crystalline structure. Scanning electron microscopy with field emission gun was used to evaluate the morphology and thickness of the films. The films grown at 400 and 500°C presented anatase phase. The film grown at 600ºC presented rutile besides anatase phase, while the film grown at 700°C showed, in addition to anatase and rutile, brookite phase. In order to evaluate the electrochemical behavior of the films cyclic voltammetry technique was used. The tests revealed that the TiO2 films formed exclusively by the anatase phase exhibit strong capacitive character. The anodic current peak is directly proportional to the square root of the scanning rate for films grown at 500ºC, suggesting that linear diffusion is the predominant mechanism of cations transport. It was observed that in the film grown during 60 minutes the Na+ ions intercalation and deintercalation easily. The films grown in the other conditions did not present the anodic current peak, although charge was accumulated in the film. (author)

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

    International Nuclear Information System (INIS)

    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

  16. Nanolaminated Al2O3-TiO2 thin films grown by atomic layer deposition

    Science.gov (United States)

    Kim, Yong Shin; Jin Yun, Sun

    2005-02-01

    Alternately stacked Al2O3-TiO2 nanolaminates were grown by atomic layer deposition (ALD) using the precursors of trimethyl aluminum, tetraisopropyl titanium, and water at growth temperature of 250 °C. Laminated configuration and nanostructural features were analyzed by cross-sectional transmission electron microscopy (TEM), depth-profiling Auger electron spectroscopy (AES) and X-ray diffraction (XRD). These material characterizations were well interpreted with layer-by-layer ALD growth mode and material properties of single oxide films, namely conformal growth of amorphous Al2O3 with a growth rate of 1.0 Å/cycle and polycrystalline anatase TiO2 with 0.3 Å/cycle. In addition, the dependences of leakage current density on applied electric field were measured for several nanolaminates with different TiO2 content and bilayer, single Al2O3 and TiO2 layer, thickness. Obtained results exhibit the successful tailoring of leakage current densities and permittivity with adjusting layer thicknesses in the nanolaminates. These properties were discussed in terms of utility as a current-controlling layer in direct current thin-film electroluminescence (TFEL) devices.

  17. Nitridation of nanocrystalline TiO2 thin films by treatment with ammonia

    International Nuclear Information System (INIS)

    Nanocrystalline anatase (TiO2) thin films prepared by a physical vapour deposition method were nitrided by annealing in flowing NH3 at temperatures ranging between 650 oC and 700 oC. It was established that there was a narrow window of temperatures which allowed both incorporation of interstitial nitrogen into the films with retention of the anatase phase without chemical reduction and preservation of the characteristic nanocrystalline morphology. These optimally modified films responded to visible light in photowetting tests and showed the ability to degrade an organic dye under visible light irradiation.

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

    Science.gov (United States)

    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.

  19. Pyrosol deposition of anatase TiO2 thin films starting from Ti(OiPr)4/acetylacetone solutions

    OpenAIRE

    Duminica, Florin-Daniel; Maury, Francis; Abisset, Sidonie

    2007-01-01

    TiO2 thin films were deposited on Si(100) and steel substrates by Pyrosol technique. The layer morphology depends on the concentration of titanium tetra-isopropoxide (TTIP) used as molecular precursor in solutions with acetylacetone (Acac). The concentration and, as a result, the viscosity of these TTIP/Acac starting solutions plays an important role on the efficiency of their nebulization and, consequently, on the microstructure and the growth kinetics of the TiO2 thin films. The correlation...

  20. Water effect on the surface morphology of TiO2 thin film modified by polyethylene glycol

    International Nuclear Information System (INIS)

    Highlights: ? TiO2 porous thin film is fabricated using polyethylene glycol 6000 (PEG-6000) as a template. ? The water molecules provide locations for the aggregation of PEG-6000, and it is demonstrated by the phase diagrams of AFM. ? The water content has an influence on the surface structure and the thin film thickness. ? The TiO2 thin film has the best photocatalytic activity when the ratio of water to Ti precursor is 2. - Abstract: Water effect on the surface morphology of TiO2 thin film was investigated by using PEG-6000 as a template to form the porous structure. The porous TiO2 thin films were characterized by thermo-gravimetric analysis (TGA), X-ray diffraction (XRD), n and k Analyzer, UVvis spectrophotometer, field-emission scanning electron microscopy (FE-SEM), and atomic forced microscopy (AFM) as a function of water content in the preparation of TiO2 thin film. The various water contents result in the TiO2 thin films possessing different surface structures, grain sizes, and thicknesses. The grain sizes were varied with changing the water content, and the thickness increased with increasing water content due to the enhancement of the cross-linking speed. In addition, the cratered surface structure transformed into cracked surface structure upon the water content beyond stoichiometric quantity because the excess water causes the aggregation of polyethylene glycol (PEG-6000). The photocatalysis has been performed by the degradation of methyl blue with corresponding structural characteristics of the TiO2 thin film. The best photocatalytic activity has been obtained when the ratio of water to titanium precursor is equal to 2 referred as TiO2-W2.

  1. Thin Functional Films of TiO2 Nanoparticles

    Czech Academy of Sciences Publication Activity Database

    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

  2. Scattering-controlled femtosecond-laser induced nanostructuring of TiO2 thin films

    Science.gov (United States)

    Das, S. K.; Rosenfeld, A.; Bock, M.; Pfuch, A.; Seeber, W.; Grunwald, R.

    2011-03-01

    The formation of laser induced periodic surface structures (LIPSS) is to a large extent of self-organizing nature and in its early stages essentially influenced by optical scattering. The evolution of related mechanisms, however, has still to be studied in detail and strongly depends on materials and laser parameters. Excitation with highly intense ultrashort pulses leads to the creation of nanoripple structures with periods far below the fundamental wavelength because of opening multiphoton excitation channels. Because of the drastically reduced spatial scale of such laser induced periodic nanostructures (LIPNS), a particular influence of scattering is expected in this special case. Here we report on first investigations of femtosecond-laser induced nanostructuring of sputtered titanium dioxide (TiO2) layers in comparison to bulk material. The crucial role of the optical film quality for the morphology of the resulting LIPNS was worked out. Typical periods of nanoripples were found to be within the range of 80-180 nm for an excitation wavelength of 800 nm. Unlike our previously reported results on bulk TiO2, LIPNS in thin films appeared preferentially at low pulse numbers (N=5-20). This observation was explained by a higher number of scattering centers caused by the thin film structure and interfaces. The basic assumptions are further supported by supplementary experiments with polished and unpolished surfaces of bulk TiO2 single crystals.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    International Nuclear Information System (INIS)

    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

  5. Methylene blue photocatalytic mineralization under visible irradiation on TiO2 thin films doped with chromium

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: We used an easy and inexpensive technique to dope thin films of TiO2. We proved that hydroxyl radicals were generated under visible light irradiation by Cr:TiO2. We used a HaberWeiss reaction through Cr:TiO2 catalyst to improve the photo-mineralization process. - Abstract: We studied changes in structural, optical and photocatalytic properties of TiO2 thin films due to doping process with chromium. Powders of undoped TiO2 and chromium-doped TiO2 (Cr:TiO2) were synthesized by solgel method and, thin films were deposited by doctor blade method. The properties of the thin films were studied by X-ray diffraction (XRD), infrared spectroscopy (IR) and diffuse reflectance. The XRD patterns indicated that doping process changed the crystalline phases radio of TiO2 thin films, furthermore, the optical analysis showed that band gap value of Cr:TiO2 thin films was 31% fewer than undoped TiO2 thin films. Along, LangmuirHinshelwood model was used to obtain kinetic information of the photo-mineralization process; results indicated that photocatalytic activity of Cr:TiO2 thin films were four times better than undoped TiO2 thin films; finally the synergic effect was tested by addition of the H2O2, photocatalytic yield was improved from 26% to 61% when methylene blue photo-mineralization was assisted with slightly amount of H2O2

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

    International Nuclear Information System (INIS)

    Highlights: ? Co or Fe doped TiO2 thin films were prepared by solgel 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 solgel 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.

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

    Science.gov (United States)

    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.

  8. Surface nanostructuring of TiO2 thin films by ion beam irradiation

    International Nuclear Information System (INIS)

    This work reports a procedure to modify the surface nanostructure of TiO2 anatase thin films through ion beam irradiation with energies in the keV range. Irradiation with N+ ions leads to the formation of a layer with voids at a depth similar to the ion-projected range. By setting the ion-projected range a few tens of nanometers below the surface of the film, well-ordered nanorods appear aligned with the angle of incidence of the ion beam. Slightly different results were obtained by using heavier (S+) and lighter (B+) ions under similar conditions

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

    International Nuclear Information System (INIS)

    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)

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

    Science.gov (United States)

    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 films on heat-sensitive substrates such as polymers. PMID:27120131

  11. Gasochromic switching of Ta and Pd-doped nanocrystalline TiO2 thin films.

    Science.gov (United States)

    Domaradzki, J; Wojcieszak, D; Prociow, E; Kaczmarek, D; Winiarski, A; Szade, J

    2011-10-01

    In this work TiO2:(Ta, Pd) thin films with gasochromic properties have been described. Thin films were prepared by reactive magnetron sputtering process using mosaic Ti-Ta-Pd target. The amounts of dopants were 2.54 at.% and 12.36 at.% of Ta and Pd, respectively. The results of optical measurements performed at presence of ethanol and additional heating of the sample up to 350 degrees C have shown an abrupt change of transmission level from 80% down to 10% in VIS and in IR range. The gasochromic change was very fast. Moreover, rapid cooling (down to room temperature) in an air ambient results in stable thin film coloration. The reverse effect (bleaching) was obtained after annealing at 500 degrees C in an ambient air. PMID:22400253

  12. Hydrogen irradiation on TiO2 nano-thin films

    International Nuclear Information System (INIS)

    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. (orig.)

  13. TiO2 thin film growth using the MOCVD method

    Directory of Open Access Journals (Sweden)

    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.

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

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    Boyadjiev, S.; Georgieva, V.; Vergov, L.; Baji, Zs; Gáber, F.; Szilágyi, I. M.

    2014-11-01

    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.

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

    International Nuclear Information System (INIS)

    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

  17. Rutherford backscattering spectrometry analysis of TiO2 thin films

    International Nuclear Information System (INIS)

    TiO2 layers grown by microwave-activated chemical bath deposition (MW) and dip coating (DC), as well as by the combination of both techniques, were studied by Rutherford backscattering spectrometry (RBS), atomic force microscopy (AFM) and scanning electron microscopy (SEM). RBS analysis allows the determination of the stoichiometry and the thickness (in atoms/cm2) of the TiO2 layers. TiO2 layers grown by DC have higher growth rates on a TiO2 film obtained by MW compared to deposition directly onto an indium-tin oxide (ITO) substrate. TiO2 layers grown by MW on a film obtained by DC have higher growth rates when compared to layers deposited onto ITO substrates. In this case, AFM analysis shows that the surface is rough and RBS reveals the presence of holes in TiO2 films

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

    International Nuclear Information System (INIS)

    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.

  19. Photocatalytic decomposition of diclofenac potassium using silver-modified TiO2 thin films

    International Nuclear Information System (INIS)

    The effects of silver insertion on the TiO2 photocatalytic activity for the degradation of diclofenac potassium were reported here. Techniques such as X-ray diffraction, scanning electron microscopy and UV-Vis spectroscopy were used to comprehend the relation between structure and properties of the silver-modified TiO2 thin films obtained by the sol-gel method. The lattice parameters and the crystallinity of TiO2 anatase phase were affected by inserted silver, and the film thickness increased about 4 nm for each 1 wt.% of silver inserted. The degradation of diclofenac potassium and by-products reached an efficiency of 4.6 mgC W-1 when the material was modified with silver. Although the first step of degradation involves only the photochemical process related to the loss of the chlorine and hydrogen atoms. This cyclization reaction leads to the formation of intermediate, which degradation is facilitated by the modified material

  20. Microstructure and elastic properties of atomic layer deposited TiO2 anatase thin films

    International Nuclear Information System (INIS)

    Amorphous TiO2 thin films were deposited by means of atomic layer deposition on Kapton substrates and then crystallized ex situ by annealing at 300 deg. C to obtain the anatase phase. The morphology, structure and microstructure of films treated for 12, 24, 72 and 90 h were investigated. The local Ti coordination changes were studied by X-ray near-edge structure (XANES). On the basis of X-ray diffraction residual stress calculations, the elastic anisotropy of the films is experimentally determined for the first time (Acomp*=0.07, Ashear*=0.03). The film macro-strains increased with the time of treatment, while the micro-strains decreased. This effect may be correlated with the incipient anatase-to-rutile transformation as suggested by the changes observed in the XANES pattern of the film treated for 90 h. However, the contribution of the substrate cannot be excluded.

  1. Photocatalytic antibacterial performance of Sn4+-doped TiO2 thin films on glass substrate

    International Nuclear Information System (INIS)

    Pure anatase, nanosized and Sn4+ ion doped titanium dioxide (TiO2) particulates (TiO2-Sn4+) were synthesized by hydrothermal process. TiO2-Sn4+ was used to coat glass surfaces to investigate the photocatalytic antibacterial effect of Sn4+ doping to TiO2 against gram negative Escherichia coli (E. coli) and gram positive Staphylococcus aureus (S. aureus). Relationship between solid ratio of TiO2-Sn4+ in coatings and antibacterial activity was reported. The particulates and the films were characterized using particle size analyzer, zeta potential analyzer, Brunauer-Emmett-Teller (BET), X-ray diffractometer (XRD), SEM, AAS and UV/VIS/NIR techniques. The results showed that TiO2-Sn4+ is fully anatase crystalline form and easily dispersed in water. Increasing the solid ratio of TiO2-Sn4+ from 10 to 50% in the coating solution increased antibacterial effect

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

    International Nuclear Information System (INIS)

    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

  3. Photocatalytic investigations of TiO2–P25 nanocomposite thin films prepared by peroxotitanic acid modified sol–gel method

    International Nuclear Information System (INIS)

    Highlights: • A modified sol–gel method was applied in order to prepare photocatalytically active TiO2–P25 nanocomposite thin films. • Peroxotitanic acid sol (PTA) was employed to produce TiO2 and TiO2–P25 nanocomposite thin films on borosilicate glasses after three dip coatings. • Band-gap investigations were performed on both TiO2 and TiO2–P25 nanocomposite thin films revealed negligible difference on their optical property. • The photocatalytic activities of TiO2–P25 nanocomposite thin films were quite superior in compared with those in TiO2 thin films. - Abstract: TiO2 thin films and TiO2–P25 nanocomposite thin films were synthesized by sol–gel method utilizing peroxotitanic acid sol (PTA). Films were obtained by three dip coatings of sol on borosilicate glasses. The crystalline size and the variation in phase of thin films were determined through X-ray diffraction. The average crystalline size of the films that was in the range of 42 nm showed a reduction in the value by increasing the rutile content. The surface morphology of the films has been characterized utilizing Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Contact-mode atomic force microscopy (AFM). The results of the morphological investigations were completely coincided with the formation of TiO2–P25 nanocomposite. The optical property of the films has been evaluated by Diffuse Reflection Spectrophotometer (DRS) at the room temperature. The obtained UV–vis spectra for both TiO2 and TiO2–P25 thin films had similar maximum wavelengths. The band gap values for the direct and indirect transitions have been measured for the TiO2 and TiO2–P25 thin films and the results showed negligible variations. The photocatalytical activity of the films was studied by photodegradation of Reactive Red 222 (RR222) under UV irradiation. The results showed that the photocatalytic efficiency of TiO2–P25 nanocomposite thin films had enhanced by the addition of rutile phase which was obviously due to the cooperation of TiO2 and P25 nanoparticles in effective charge transfer process. Additionally, photodegradation rate constant result calculations for the TiO2–P25 nanocomposite thin films can well exhibit the increase in its photocatalytic performance in comparison with TiO2 thin films

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

    KAUST Repository

    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.

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

    Indian Academy of Sciences (India)

    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.

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

    International Nuclear Information System (INIS)

    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 on 400 oC substrates and annealed at 450 oC for 1 h consisted of both anatase and rutile. Thus, although the XRD analyses could not indicate the underlying phase of the amorphous films, it could be determined by the optical analyses.

  7. Sensitizing mechanism and adsorption properties of dye-sensitized TiO2 thin films

    International Nuclear Information System (INIS)

    The dye-sensitized TiO2 complex films were prepared by the dye coat onto TiO2 surfaces, and the sensitizing mechanism and adsorption properties of the dye-sensitized TiO2 complex films were investigated. The influence of the application conditions of dye adsorbed on TiO2 films on the amount of dye adsorption was discussed. Experimental results show that the concentration, the temperature of dye solutions and the dipping time of TiO2 films in the dye solutions have a significant influence on the amount of dye adsorption. Cell test indicates that the conversion efficiency of light to electricity increases with the amount of dye adsorption

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

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

    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.

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

    Science.gov (United States)

    Yeniyol, Sinem; Mutlu, Ilven; He, Zhiming; Yksel, Behiye; Boylan, Robert Joseph; rgen, Mustafa; Karabuda, Zihni Cneyt; Basegmez, Cansu; Ricci, John Lawrence

    2015-01-01

    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 (25?m) and protruding hills (1050?m) 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. PMID:26576430

  12. Dry Etching Properties of TiO2 Thin Film Using Inductively Coupled Plasma for Resistive Random Access Memory Application

    Directory of Open Access Journals (Sweden)

    Young-Hee Joo

    2012-06-01

    Full Text Available In this work, we investigated to the etching characteristics of TiO2 thin film and the selectivity using the inductivelycoupled plasma system. The etch rate and the selectivity were obtained with various gas mixing ratios. The maximumetch rate of TiO2 thin film was 61.6 nm/min. The selectivity of TiO2 to TiN, and TiO2 to SiO2 were obtained as 2.13 and1.39, respectively. The etching process conditions are 400 W for RF power, -150 V for DC-bias voltage, 2 Pa for theprocess pressure, and 40? for substrate temperature. The chemical states of the etched surfaces were investigatedwith X-ray photoelectron spectroscopy (XPS. Its analysis showed that the etching mechanism was based on thephysical and chemical pathways in the ion-assisted physical reaction.

  13. Cathodic cage plasma deposition of TiN and TiO2 thin films on silicon substrates

    International Nuclear Information System (INIS)

    Cathodic cage plasma deposition (CCPD) was used for growing titanium nitride (TiN) and titanium dioxide (TiO2) thin films on silicon substrates. The main advantages of the CCPD technique are the uniformity, tridimensionality, and high rate of the film deposition that occurs at higher pressures, lower temperatures, and lower treatment times than those used in conventional nitriding treatments. In this work, the influence of the temperature and gas atmosphere upon the characteristics of the deposited films was investigated. The TiN and TiO2 thin films were characterized by x-ray diffraction, scanning electron microscopy, and Raman spectroscopy to analyze their chemical, structural, and morphological characteristics, and the combination of these results indicates that the low-cost CCPD technique can be used to produce even and highly crystalline TiN and TiO2 films

  14. Structural study of TiO2 thin films by micro-Raman spectroscopy

    Science.gov (United States)

    Niilisk, Ahti; Moppel, Mart; Pärs, Martti; Sildos, Ilmo; Jantson, Taavi; Avarmaa, Tea; Jaaniso, Raivo; Aarik, Jaan

    2006-03-01

    The Raman spectroscopy method was used for structural characterization of TiO2 thin films prepared by atomic layer deposition (ALD) and pulsed laser deposition (PLD) on fused silica and single-crystal silicon and sapphire substrates. Using ALD, anatase thin films were grown on silica and silicon substrates at temperatures 125-425 °C. At higher deposition temperatures, mixed anatase and rutile phases grew on these substrates. Post-growth annealing resulted in anatase-to-rutile phase transitions at 750 °C in the case of pure anatase films. The films that contained chlorine residues and were amorphous in their as-grown stage transformed into anatase phase at 400 °C and retained this phase even after annealing at 900 °C. On single crystal sapphire substrates, phase-pure rutile films were obtained by ALD at 425 °C and higher temperatures without additional annealing. Thin films that predominantly contained brookite phase were grown by PLD on silica substrates using rutile as a starting material.

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

    OpenAIRE

    Emerson Henrique de Faria; Alex Lemes Marçal; Eduardo José Nassar; Katia Jorge Ciuffi; Paulo Sergio Calefi

    2007-01-01

    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 ch...

  16. Optimization and characterization of transparent photocatalytic TiO2 thin films prepared by ion-assisted deposition

    Science.gov (United States)

    Boughaled, Redouan; Schlichting, Sebastian; Ehlers, Henrik; Ristau, Detlev; Bannat, Inga; Wark, Michael

    2008-09-01

    The term photocatalysis is used to describe a photon-driven catalytic process. Titanium dioxide is a well-known photocatalyst in such fields as self-cleaning material and anti-microbial effects. Besides these photocatalytic applications, TiO2 is a widely-used high index material for optical thin films. In the present investigation, the photocatalytic activity of transparent TiO2 thin films was optimized to achieve multifunctional high precision optical coatings. The films have been deposited by ion assisted deposition (IAD), applying a Leybold APS plasma source as well as a Denton CC-105 ion source. The cause-and-effect chain between the use of different parameters in the IAD process and optical properties of the TiO2 layers as well as their photocatalytic activities are described. As test reaction for the determination of the photocatalytic properties, the degradation of methylene blue (MB) was chosen. The used setup based on a high precision two-path laser measurement system was developed by the LZH in order to determine the kinetic performance of TiO2 catalysts under well-defined UV illumination conditions. Photonic efficiencies of the TiO2 thin films were calculated from the obtained data. Additionally, crystal structure analysis has been investigated for the identification of anatase and rutile modifications. The comparison of the results shows that ion assisted deposition is an appropriate technology for the preparation of photocatalytic active thin films for optical applications.

  17. Power-law photoconductivity time decay in nanocrystalline TiO2 thin films

    International Nuclear Information System (INIS)

    The sub-band-gap excited photoconductivity (PC) time decay and the film structure of rf-sputter deposited nanocrystalline TiO2 thin films have been studied. Atomic force microscopy and x-ray diffraction measurements were used to assess roughness, crystalline structure and mean grain size of the films. Samples fabricated under different deposition conditions exhibit different microstructures and absolute PC, but similar persistent PC behaviour after switching off the light source. The very slow PC decay can be well represented by a function that is nearly constant for short times and decreases as a power law for times longer than about 100 s. This function is shown to be consistent with a rate equation characterized by a relaxation time that increases linearly with time. This behaviour, in turn, agrees with predictions of a previously reported model that assumes electron-hole recombination limited by carrier-density-dependent potential barriers associated with inhomogeneities. These results may have important implications on attempts to determine distributions of trap energies from PC decay curves in TiO2

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

    International Nuclear Information System (INIS)

    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)

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

    Science.gov (United States)

    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.

  20. Influence of Nd dopant amount on microstructure and photoluminescence of TiO2:Nd thin films

    Science.gov (United States)

    Wojcieszak, Damian; Mazur, Michal; Kaczmarek, Danuta; Morgiel, Jerzy; Zatryb, Grzegorz; Domaradzki, Jaroslaw; Misiewicz, Jan

    2015-10-01

    TiO2 and TiO2:Nd thin films were deposited using reactive magnetron sputtering process from mosaic Ti-Nd targets with various Nd concentration. The thin films were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and spectroscopic techniques. Photoluminescence (PL) in the near infrared obtained upon 514.5 nm excitation was also examined. The relationship between the Nd concentration, structural, optical and photoluminescence properties of prepared thin films was investigated and discussed. XRD and TEM measurements showed that an increase in the Nd concentration in the thin films hinders the crystal growth in the deposited coatings. Depending on the Nd amount in the thin films, TiO2 with the rutile, mixed rutile-amorphous or amorphous phase was obtained. Transmittance measurements revealed that addition of Nd dopant to titania matrix did not deteriorate optical transparency of the coatings, however it influenced on the position of the fundamental absorption edge and therefore on the width of optical band gap energy. All TiO2:Nd thin films exhibited PL emission that occurred at ca. 0.91, 1.09 and 1.38 μm. Finally, results obtained for deposited coatings showed that titania with the rutile structure and 1.0 at.% of Nd was the most efficient in VIS to NIR photon conversion.

  1. Synthesis and characterization of TiO2 thin films doped with copper to be used in photocatalysis / Sntesis y caracterizacin de pelculas delgadas de TiO2 dopadas con cobre para ser usadas en fotocatlisis

    Scientific Electronic Library Online (English)

    Carlos Enrique, Daz-Uribe; William Andrs, Vallejo Lozada; Fernando, Martnez Ortega.

    2013-06-01

    Full Text Available In this work we studied the influence of incorporation of copper into TiO2 thin films on structural, optical and surface properties of TiO2 thin films. The as-grown TiO2 was synthesized by sol gel method using titanium isopropoxide, and the TiO2 thin films were deposited by spin coating method. TiO2 [...] copper-doped (Cu:TiO2) was synthesized by impregnation method using Cu(NO3).H2O as source of Cu(II), the Cu:TiO2 thin films were deposited by spin coating method. The properties of the compounds obtained were evaluated by measurements of X-ray diffraction (XRD) and diffuse reflectance. The XRD results showed that Cu doping change the crystalline phase radio of the films, XRD pattern of TiO2 indicated that films grow with anatase structute, while Cu:TiO2 thin films presented a polycrystalline mixture of anatase/rutile. Reflectance analysis indicated that TiO2 presents an energy band gap of 3.25 eV and the Cu:TiO2 presents a shift-red of the band gap to 2,9 eV. The results suggest that doping with copper improved the harvesting of the TiO2 to visible radiation.

  2. Thin Tin and Tio2 Film Deposition in Glass Samples by Cathodic Cage

    Scientific Electronic Library Online (English)

    Rmulo Ribeiro Magalhes de, Sousa; Francisco Odolberto de, Arajo; Thercio Henrique de Carvalho, Costa; Igor Oliveira, Nascimento; Francisco Eroni Paes, Santos; Clodomiro, Alves Jnior; Michelle Cequeira, Feitor.

    2015-04-01

    Full Text Available Thin nitride and titanium dioxide films were produced using an innovative technique called cathodic cage depositon. Uniformity, three-dimensionality and high rate deposition are some of the advantages of this technique. In this study we discuss the influences of temperature, treatment time and gaseo [...] us atmosphere on the characteristics of the deposited films. The TiN (titanium nitride) and TiO2 (titanium dioxide) films were produced using a high deposition rate of 2,5 m/h at a work temperature and pressure of 400C and 150 Pa respectively. EDS technique was used to identify the chemical composition of the thin film deposited, whilst Raman spectroscopy indicated the phases present confirmed by DRX analysis. The thickness of the deposited films was studied using electron microscopy scanning. The results based on the deposition parameters confirm the great efficiency and versatility of this technique, which allows a uniform three-dimensional film deposition on any material without the appearance of stress. Compared to other techniques, cathodic cage deposition enables deposition at lower temperatures and higher pressures.

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

    OpenAIRE

    Hairong Wang; Lei Chen; Jiaxin Wang; Quantao Sun; Yulong Zhao

    2014-01-01

    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. ...

  4. Nanostructured TiO2/carbon nanosheet hybrid electrode for high-rate thin-film lithium-ion batteries

    Science.gov (United States)

    Moitzheim, S.; Nimisha, C. S.; Deng, Shaoren; Cott, Daire J.; Detavernier, C.; Vereecken, P. M.

    2014-12-01

    Heterogeneous nanostructured electrodes using carbon nanosheets (CNS) and TiO2 exhibit high electronic and ionic conductivity. In order to realize the chip level power sources, it is necessary to employ microelectronic compatible techniques for the fabrication and characterization of TiO2-CNS thin-film electrodes. To achieve this, vertically standing CNS grown through a catalytic free approach on a TiN/SiO2/Si substrate by plasma enhanced chemical vapour deposition (PECVD) was used. The substrate-attached CNS is responsible for the sufficient electronic conduction and increased surface-to-volume ratio due to its unique morphology. Atomic layer deposition (ALD) of nanostructured amorphous TiO2 on CNS provides enhanced Li storage capacity, high rate performance and stable cycling. The amount of deposited TiO2 masks the underlying CNS, thereby controlling the accessibility of CNS, which gets reflected in the total electrochemical performance, as revealed by the cyclic voltammetry and charge/discharge measurements. TiO2 thin-films deposited with 300, 400 and 500 ALD cycles on CNS have been studied to understand the kinetics of Li insertion/extraction. A large potential window of operation (3-0.01 V); the excellent cyclic stability, with a capacity retention of 98% of the initial value; and the remarkable rate capability (up to 100 C) are the highlights of TiO2/CNS thin-film anode structures. CNS with an optimum amount of TiO2 coating is proposed as a promising approach for the fabrication of electrodes for chip compatible thin-film Li-ion batteries.

  5. Nb-doped TiO2 thin films as photocatalytic materials

    Indian Academy of Sciences (India)

    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.

  6. TiO 2 thin films doped with Pd and Eu for optically and electrically active TOS-Si heterojunction

    Science.gov (United States)

    Kaczmarek, Danuta; Domaradzki, Jaroslaw; Prociow, Eugeniusz L.; Berlicki, Tadeusz; Prociow, Krystyna

    2009-07-01

    In this work, optical and electrical characterization of transparent Eu and Pd-doped TiO 2 thin films has been presented. Thin films of TiO 2 doped with Eu (0.9 at.%) and Pd (5.8 at.%) were deposited on silicon and glass substrates from Ti-Eu-Pd mosaic target using modified magnetron sputtering method. X-ray diffraction measurements revealed nanocrystalline structure with the only rutile phase of TiO 2 in prepared thin films. Pd-doping, through formation of discontinuous paths for charge carriers brings the enhanced electrical conductivity and makes prepared thin films oxide semiconductors. It has been shown, that Eu dopant acts as an optical activator of light conversion from UV to the red-visible, corresponding to the optical working range of standard silicon devices. From electrical measurements it was found out that Eu-doping of TiO 2 results in the n-type of electrical conduction. From optical transmission spectroscopy measurements position of the fundamental absorption edge and optical band-gap energy have been determined. The current to voltage dependence and photovoltage observations confirmed the formation of heterojunction at thin film-silicon interface.

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

    Indian Academy of Sciences (India)

    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.

  8. Mesoporous TiO2 thin films embedded with Au nanoparticles for the enhancement of the photocatalytic properties

    International Nuclear Information System (INIS)

    Mesoporous TiO2 thin films were prepared by hydrothermal-oxidation of titanium metal thin films, which were obtained by DC magnetron sputtering technique. Gold nanoparticles, which were prepared by reduction of HAuCl4, were embedded into the holes of the mesoporous TiO2 films by capillary method followed by annealing in air up to 400 oC. The size of pore of TiO2 films is about 100 nm and that of Au nanoparticles is about 10 nm in average. The morphology of the films was analyzed by field emission scanning electron microscope (FE-SEM) and scanning probe microscopes (SPMs). Subsequently, the photocatalytic performances of the obtained nanosystems in the decomposition of methylene blue solution are discussed. The obtained results show that the dispersion of Au nanoparticles on the mesoporous TiO2 matrix will help enhancing the photocatalytic activity with respect to pure TiO2 under visible light irradiation.

  9. Contact Angle of TiO2/SnO2 Thin Films Coated on Glass Substrate

    Directory of Open Access Journals (Sweden)

    Weerachai SANGCHAY

    2014-05-01

    Full Text Available The self-cleaning effect in terms of contact angle value and photocatalytic activity of TiO2 and TiO2/SnO2 thin films coated on glass substrate was measured. The thin films were prepared using a sol-gel dip coating technique and calcinated at a temperature of 500 °C for 2 h with a heating rate of 10 °C/min. The microstructures of the fabricated thin films were characterized by SEM and XRD techniques. The photocatalytic properties of the thin films were also tested via the degradation of methylene blue (MB solution under UV irradiation. Finally, the self-cleaning properties of the thin films were evaluated by measuring the contact angle of water droplets on the thin films with and without UV irradiation. It was found that 1 %mol SnO2/TiO2 thin films showed the highest of photocatalytic activity and provided the most self-cleaning properties.doi:10.14456/WJST.2014.21

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

    International Nuclear Information System (INIS)

    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 electron diffraction. A Ru-containing dye was incorporated in some films, and energy-dispersive X-ray microanalysis was then used to assess the distribution of dye in the cross-sections. Cross-section preparation by the more conventional method of ion-beam thinning can produce thinner specimens and allows the interface between the film and substrate to be studied, but the procedure is more time-consuming. However ultramicrotomy can be a useful complementary technique for relatively rapid TEM examination of thin film cross-sections. Copyright (2002) Australian Society for Electron Microscopy Inc

  11. Photodecomposition effects of graphene oxide coated on TiO2 thin film prepared by electron-beam evaporation method

    International Nuclear Information System (INIS)

    Morphological, structural and photocatalytic properties of graphene oxide (GO)/TiO2 thin-film deposited on quartz substrate were investigated. The TiO2 film was prepared by electron-beam evaporation and the GO film by spin coating method. The photocatalytic activities of the GO/TiO2 film were evaluated by photodecomposition of methylene blue. There was synergistic effect between TiO2 and GO which causes a rapid photo-induced charge separation and the reduction of the recombination of electronhole pairs under the UVvisible light irradiation. GO on TiO2 film also promotes the properties of adsorption of the dye, photon scattering probability, and interacting surface area. As a result, it leads to the enhancement of the efficiency of the photodegradation in GO/TiO2 film. - Highlights: ? Graphene oxide (GO)/TiO2 film exhibited improved charge separation and transport. ? GO/TiO2 had higher photon scattering on surface and better adsorption than the TiO2. ? Recombination of electronhole pairs reduced under the UVvisible irradiation. ? Hydroxyl and epoxide groups in GO reduced during the photocatalytic process. ? TiO2 achieved anatase phase by electron-evaporation method.

  12. Hierarchical porous TiO2 thin films by soft and dual templating

    International Nuclear Information System (INIS)

    Hierarchical porous structures, with different pore sizes, including pores larger than 10 nm, constitute an important field of research for many applications such as selective molecule detection, catalysis, dye-sensitized solar cells, nanobiotechnology and nanomedecine. However, increasing the pore size logically results in the decrease of specific surface. There is a need to quantify and predict the resulting porosity and specific surface. We have prepared hierarchical porous TiO2 thin films either by surfactant templating (soft) or dual surfactant/nanospheres templating (soft/hard). They all show narrow, bimodal distribution of pores. Soft templating route uses a modified sol–gel procedure by adding a swelling agent (polypropylene glycol) to a precursor solution containing Ti alkoxide and block-copolymer surfactant. This scheme leads to very thin films showing high specific surface and bimodal porosity with diameters of 10 nm and 54 nm. Dual templating route combines a precursor solution made of Ti alkoxide and block-copolymer surfactant with polystyrene (PS) nanospheres (diam. 250 nm) in a one-pot simple process. This gives thicker films with a bimodal distribution of pores (8 nm and 165-200 nm). The introduction of PS nanospheres in the surfactant–Ti system does not interfere with the soft templating process and results in a macroporosity with a pore diameter 20–30% smaller than the original beads diameter. The dye loading of hierarchical films is compared to pure surfactant-templated TiO2 films and shows a relative decrease of 29% for soft templating and 43% for dual templating. The microstructure of bimodal porous films is characterized by several techniques such as transmission and scanning electron microscopy, X-ray diffraction, profilometry and ellipsometry. Finally, a geometrical model is proposed and validated for each system, based on the agreement between calculated specific surfaces and experimental dye loading with N719 dye. - Highlights: • Hierarchical porous thin films are prepared by soft and dual templating. • A geometrical model predicts the total specific surface of bimodal porous materials. • The model is validated by dye-loading experiments

  13. Resistive switching characteristics of TiO2 thin films with different electrodes

    Science.gov (United States)

    Shim, Jae Hyuk; Hu, Quanli; Park, Mi Ra; Abbas, Yawar; Kang, Chi Jung; Kim, Jaewan; Yoon, Tae-Sik

    2015-09-01

    Resistive switching behaviors in metal oxides have been mentioned for several decades. TiO2 is still a well-known material for resistive switching memory devices. The resistive switching characteristics of TiO2 thin films with different top electrodes were investigated. The devices had typical bipolar resistive switching behaviors. The resistance changed from a high-resistance state (low-resistance state) to a low-resistance state (high-resistance state) under positive (negative) sweeping voltage. The interface between the top electrode and the oxide layer could affect the resistive switching behaviors. The electrical properties of Metal/TiO2/Pt devices with different top electrodes showed different switching characteristics. The conduction mechanism of the devices was also investigated. In the low-resistance state, ohmic conduction was dominant. The conduction mechanism exhibited ohmic conduction at low voltages and space-charge-limited-conduction at high voltages in the devices of Cu/TiO2/Pt, Ni/TiO2/Pt and Al/TiO2/Pt, respectively. For Ta/TiO2/Pt Schottky conduction also played an important role.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    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 dB?cm-1.

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

    International Nuclear Information System (INIS)

    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

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

    Directory of Open Access Journals (Sweden)

    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.

  18. Investigation on surface roughness in chemical mechanical polishing of TiO2 thin film

    International Nuclear Information System (INIS)

    Surface roughness by peaks and depressions on the surface of titanium dioxide (TiO2) thin film, which was widely used for an antireflection coating of optical systems, caused the extinction coefficient increase and affected the properties of optical system. Chemical mechanical polishing (CMP) is a very important method for surface smoothing. In this polishing experiment, we used self-formulated weakly alkaline slurry. Other process parameters were working pressure, slurry flow rate, head speed, and platen speed. In order to get the best surface roughness (1.16 Å, the scanned area was 10 × 10 μm2) and a higher polishing rate (60.8 nm/min), the optimal parameters were: pressure, 1 psi; slurry flow rate, 250 mL/min; polishing head speed, 80 rpm; platen speed, 87 rpm. (semiconductor materials)

  19. Rutherford backscattering analysis of porous thin TiO2 films

    International Nuclear Information System (INIS)

    The additional energy spread due to sample porosity was implemented in the SIMNRA simulation code, version 6.60 and higher. Deviations of the path length and energy loss distributions from the ones expected from a Poisson distribution of the number of traversed pores are taken into account. These deviations are due to the interaction of pores at higher pore concentrations by overlap or blocking. The skewnesses of the energy distributions are approximated by two-piece normal distributions with identical first three moments. Propagation of porosity-induced energy spread in thick layers is taken into account. Calculated results are compared to experimental data obtained with thin TiO2 mesoporous films measured by Rutherford backscattering (RBS),transmission electron microscopy (TEM), and atmospheric poroellipsometry.

  20. Optimization of TiO2 Thin Film Growth at Different Temperatures by Atomic Layer Deposition

    OpenAIRE

    Su, Jie

    2011-01-01

    In this work TiO2 films were grown on silicon substrates by atomic layer deposition (ALD) using TiCl4 and H2O as precursors. The effect of precursor pulse length and reaction temperature on the film growth rate and film uniformity was studied. The film thickness and refractive indices were measured by ellipsometry. The simulation of TiO2 growth with different TiCl4 pulsing lengths was carried out. The results indicated that in an appropriate temperature range the growth rate and the unif...

  1. Improved performance of CdSe quantum dot-sensitized TiO2 thin film by surface treatment with TiCl4

    International Nuclear Information System (INIS)

    A TiO2 nanocrystalline thin film, sensitized by CdSe quantum dots, was further modified by a TiCl4 treatment strategy. The CdSe quantum dots with a cubic zinc blende structure were synthesized in situ on the TiO2 nanocrystalline thin films by chemical bath deposition, after which the sensitized TiO2 film was further modified by a TiCl4 treatment strategy. The modification of the amorphous TiO2 thin layer enhanced the photovoltaic performance of the quantum dot-sensitized thin film. This enhancement was detected by fabricating a solar cell based on the sensitized thin film electrode, a polysulfide electrolyte and a platinized electrode. The modified amorphous TiO2 was partly crystallized by heating the film at 200 C to analyze the effect of crystallization on interfacial recombination and the photovoltaic performance. The enhancement due to the TiCl4 treatment was attributed to the formation of an amorphous TiO2 thin layer, which separated the uncovered surface of TiO2 nanoparticles from the electrolyte, and reduced the surface states of the TiO2 nanocrystals and the quantum dots. The highest conversion efficiency was 2.13%, and it was obtained for the quantum dot-sensitized solar cell after optimizing the CdSe quantum dot deposition and amorphous TiO2 thin layer modification processes.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

  4. Enhanced bolometric properties of TiO2-x thin films by thermal annealing

    Science.gov (United States)

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

    2015-07-01

    The effect of thermal annealing on the bolometric properties of TiO2-x films was investigated. The test-patterned TiO2-x samples were annealed at 300 °C temperature in order to enhance their structural and electrical properties for effective infrared image sensor device applications. The crystallinity was changed from amorphous to rutile/anatase in annealed TiO2-x films. Compared to the as-deposited samples, a decrement of the band gap and a decrease of the electrical resistivity were perceived in annealed samples. We found that the annealed samples show linear current-voltage (I-V) characteristic performance, which implies that ohmic contact was well formed at the interface between the TiO2-x and the Ti electrode. Moreover, the annealed TiO2-x sample had a significantly low 1/f noise parameter (1.21 × 10-13) with a high bolometric parameter (β) value compared to those of the as-deposited samples. As a result, the thermal annealing process can be used to prepare TiO2-x film for a high-performance bolometric device.

  5. The properties of metal contacts on TiO2 thin films produced by reactive magnetron sputtering

    Directory of Open Access Journals (Sweden)

    Brus V. V.

    2010-10-01

    Full Text Available The article deals with research on volt-ampere characteristics of metal contacts (Al, Cr, In, Mo, Ti on titanium dioxide thin films and influence of annealing in vacuum on their electric properties. Volt-ampere characteristics measurements were taken by three-probe method. There was established that indium contact on TiO2 thin films possessed sharply defined ohmic properties.

  6. Substrate-controlled allotropic phases and growth orientation of TiO2 epitaxial thin films

    International Nuclear Information System (INIS)

    TiO2 thin films were grown by pulsed laser deposition on a wide variety of oxide single-crystal substrates and characterized in detail by four-circle X-ray diffraction. Films grown at 873 K on (100)-oriented SrTiO3 and LaAlO3 were (001)-oriented anatase, while on (100) MgO they were (100)-oriented. On (110) SrTiO3 and MgO, (102) anatase was observed. On M-plane and R-plane sapphire, (001)- and (101)-oriented rutile films were obtained, respectively. On C-plane sapphire, the coexistence of (001) anatase, (112) anatase and (100) rutile was found; increasing the deposition temperature tended to increase the rutile proportion. Similarly, films grown at 973 K on (100) and (110) MgO showed the emergence, besides anatase, of (110) rutile. All these films were epitaxically grown, as shown by ? scans and/or pole figures, and the various observed orientations were explained on the basis of misfit considerations and interface arrangement. (orig.)

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

    International Nuclear Information System (INIS)

    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

  8. Biological behaviour of thin films consisting of Au nanoparticles dispersed in a TiO2 dielectric matrix

    OpenAIRE

    Borges, Joel; Costa, D.; Antunes, E; Lopes, Cláudia Jesus Ribeiro; Rodrigues, M. S.; Apreutesei, M.; E. Alves; Barradas, N. P.; P. PEDROSA; Moura, C; Cunha, L., da; Polcar, T.; Vaz, F.; Sampaio, Paulo

    2015-01-01

    In this work it was studied the possible use of thin films, composed of Au nanoparticles (NPs) embedded in a TiO2 matrix, in biological applications, by evaluating their interaction with a well-known protein, Bovine Serum Albumin (BSA), as well as with microbial cells (Candida albicans). The films were produced by one-step reactive DC magnetron sputtering followed by heat-treatment. The samples revealed a composition of 8.3 at.% of Au and a stoichiometric TiO2 matrix. The annealing promoted g...

  9. Photodegradation of reactive red 222 using TiO2 nanostructured thin films prepared by modified sol-gel method

    OpenAIRE

    F. Oshani; Rasouli, S.; R. Marandi; M. Keramati Farhoud

    2014-01-01

    In this paper, a modified sol-gel method using peroxotitanic acid sol (PTA) was applied for the preparation of TiO2 nanostructured thin films on glass plates. The peroxotitanic acid sol was synthesized using titanium isopropoxide, isopropylalchol, H2O and hydrogen peroxide. TiO2 films were then calcined at 500oC and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD results showed that increasing the number of coated layers would lead to the formation of anat...

  10. TiO2 thin film transistor by atomic layer deposition

    Science.gov (United States)

    Okyay, Ali K.; Oruç, Feyza; ćimen, Furkan; Aygün, Levent E.

    2013-03-01

    In this study, TiO2 films were deposited using thermal Atomic Layer Deposition (ALD) system. It is observed that asdeposited ALD TiO2 films are amorphous and not suitable as TFT channel material. In order to use the film as channel material, a post-annealing process is needed. Annealed films transform into a polycrystalline form containing mixed anatase and rutile phases. For this purpose, devices are annealed at 475°C and observed that their threshold voltage value is 6.5V, subthreshold slope is 0.35 V/dec, Ion/Ioff ratios 2.5×106 and mobility value is 0.672 cm2/V.s. Optical response measurements showed that devices exhibits decent performance at ultraviolet region where TiO2 has band to band absorption mechanism.

  11. Formation of TiO2 domains in Poly (9-vinylcarbazole) thin film by hydrolysis-condensation of a metal alkoxide

    International Nuclear Information System (INIS)

    New organic-inorganic hybrid thin films based on Poly (9-vinylcarbazole) (P9VK) and Dioxide titanium (TiO2) bulk-heterojunction were obtained by a hydrolysis-condensation (H-C) process of titanium (IV) isopropoxide in thin film. The TiO2 distribution in the film was investigated by scanning electron microscopy. The results indicated that homogeneous TiO2 particles around 100 nm were formed on the surface of the polymer thin film. Photoluminescence spectroscopy has been used to study the charge transfer efficiency in the photoactive layer and results were compared with a simplest elaboration route, the dispersion of TiO2 anatase in a P9VK solution before spin coating. Results showed that TiO2 elaborated by H-C exhibits a competitive quenching effect with TiO2 anatase

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

    Indian Academy of Sciences (India)

    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.

  13. The role of energetic ion bombardment during growth of TiO2 thin films by reactive sputtering

    OpenAIRE

    A Amin; Köhl, D; Wuttig, M.

    2010-01-01

    Abstract TiO 2 thin films have been deposited by several different sputtering processes: i) dc Magnetron Sputtering (dcMS) employing various geometrical conditions, ii) Ion-Assisted dc Magnetron Sputtering (IAS) where additional ion bombardment of the growing films was performed with an auxiliary ECR ion source and iii) High Power Impulse Magnetron Sputtering (HiPIMS). Films have been investigated mainly by grazing incidence X-ray diffraction and atomic force microscopy. It is shown that t...

  14. Correlation lengths, porosity and water adsorption in $TiO_2$ thin films prepared by glancing angle deposition

    OpenAIRE

    Gonzalez-Garcia, L.; Parra-Barranco, J.; Sanchez-Valencia, J. R.; Barranco, A.; Borras, A.; Gonzalez-Elipe, A. R.; Garcia-Gutierrez, M.-C.; Hernandez, J J.; Rueda, D. R.; Ezquerra, T A

    2012-01-01

    This paper reports a thorough microstructural characterization of glancing angle deposited (GLAD) TiO(2) thin films. Atomic force microscopy (afm), grazing-incidence small-angle x-ray scattering (GISAXS) and water adsorption isotherms have been used to determine the evolution of porosity and the existence of some correlation distances between the nanocolumns constituting the basic elements of the film's nanostructure. It is found that the deposition angle and, to a lesser extent, the film thi...

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

    Directory of Open Access Journals (Sweden)

    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 500C. 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.

  16. Synthesis, phase to phase deposition and characterization of rutile nanocrystalline titanium dioxide (TiO2) thin films

    Science.gov (United States)

    Gupta, Sanjeev K.; Singh, Jitendra; Anbalagan, K.; Kothari, Prateek; Bhatia, Ravi Raj; Mishra, Pratima K.; Manjuladevi, V.; Gupta, Raj K.; Akhtar, J.

    2013-01-01

    In this work the preparation, deposition and structural properties of titanium oxide (TiO2) thin films were investigated. The films were deposited by means of the e-beam physical vapor deposition (EBPVD) method in high vacuum (10-7 Torr). A controlled deposition rate in the range of 0.1-0.3 Å/s was monitored in situ employing quartz crystal. The films were deposited on the oxidized Si (1 0 0) wafer, glass micro slides. These films were analyzed using Grazing Angle X-ray diffraction (GA-XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy (RAMAN), Atomic Force Microscopy (AFM) and UV-visible Spectroscopy (UV-vis). Structural characterization results showed mainly presence of the crystalline rutile phase, however an interfacial SiO2 layer between TiO2 and the substrate and the minor anatase crystalline phase of TiO2 was also identified in FTIR analysis. Grain size was found to be in the range of 100-125 nm while grain boundary was estimated to be 20 nm. Direct and indirect optical band gap was estimated to be 3.64 and 3.04 eV, respectively. A process induced self annealing of deposited film shows a strong effect on the structural, morphological and optical properties. Furthermore, low deposition rate and high vacuum allows rutile to rutile phase transformation from indigenously prepared TiO2 target to thin film.

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

    Science.gov (United States)

    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 365C. At deposition temperatures above 330C, 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 330C, 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 750C. 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.

  18. Synthesis of Ag ion-implanted TiO2 thin films for antibacterial application and photocatalytic performance.

    Science.gov (United States)

    Hou, Xinggang; Ma, Huiyan; Liu, Feng; Deng, Jianhua; Ai, Yukai; Zhao, Xinlei; Mao, Dong; Li, Dejun; Liao, Bin

    2015-12-15

    TiO2 thin films were deposited by spin coating method. Silver ions were implanted into the films using a Metal Vapor Vacuum Arc implanter. The antibacterial ability of implanted films was tested using Escherichia coli removal under fluorescent irradiation and in the dark. The concentration of E. coli was evaluated by plating technique. The photocatalytic efficiency of the implanted films was studied by degradation of methyl orange under fluorescent illumination. The surface free energy of the implanted TiO2 films was calculated by contact angle testing. Vitamin C was used as radical scavengers to explore the antibacterial mechanism of the films. The results supported the model that both generation of reactive oxygen species and release of silver ions played critical roles in the toxic effect of implanted films against E. coli. XPS experimental results demonstrated that a portion of the Ag(Ag(3+)) ions were doped into the crystalline lattice of TiO2. As demonstrated by density functional theory calculations, the impurity energy level of subtitutional Ag was responsible for enhanced absorption of visible light. Ag ion-implanted TiO2 films with excellent antibacterial efficiency against bacteria and decomposed ability against organic pollutants could be potent bactericidal surface in moist environment. PMID:26093355

  19. Visualization of local phase transition behaviors near dislocations in epitaxial VO2/TiO2 thin films

    Science.gov (United States)

    Sohn, Ahrum; Kanki, Teruo; Tanaka, Hidekazu; Kim, Dong-Wook

    2015-10-01

    We investigated local phase transition behaviors in epitaxial VO2/TiO2 thin films using variable-temperature Kelvin probe force microscopy while spanning the metal-insulator transition (MIT). Fully strained thin films were almost free of grain boundaries. In contrast, thicker films had cracks (dislocations) caused by strain relaxation. The surface area fraction of the insulating phase near the dislocations was higher than that in other regions. Thicker films have complicated domain patterns; hence, the three-dimensional percolation model properly described the MIT behaviors. In contrast, the two-dimensional percolation model well explained the transition behaviors of uniformly strained thinner films.

  20. Annealing dependence of residual stress and optical properties of TiO2 thin film deposited by different deposition methods.

    Science.gov (United States)

    Chen, Hsi-Chao; Lee, Kuan-Shiang; Lee, Cheng-Chung

    2008-05-01

    Titanium oxide (TiO(2)) thin films were prepared by different deposition methods. The methods were E-gun evaporation with ion-assisted deposition (IAD), radio-frequency (RF) ion-beam sputtering, and direct current (DC) magnetron sputtering. Residual stress was released after annealing the films deposited by RF ion-beam or DC magnetron sputtering but not evaporation, and the extinction coefficient varied significantly. The surface roughness of the evaporated films exceeded that of both sputtered films. At the annealing temperature of 300 degrees C, anatase crystallization occurred in evaporated film but not in the RF ion-beam or DC magnetron-sputtered films. TiO(2) films deposited by sputtering were generally more stable during annealing than those deposited by evaporation. PMID:18449260

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

    International Nuclear Information System (INIS)

    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. TiO(2)/LiCl-based nanostructured thin film for humidity sensor applications.

    Science.gov (United States)

    Buvailo, Andrii I; Xing, Yangjun; Hines, Jacqueline; Dollahon, Norman; Borguet, Eric

    2011-02-01

    A simple and straightforward method of depositing nanostructured thin films, based on LiCl-doped TiO(2), on glass and LiNbO(3) sensor substrates is demonstrated. A spin-coating technique is employed to transfer a polymer-assisted precursor solution onto substrate surfaces, followed by annealing at 520C to remove organic components and drive nanostructure formation. The sensor material obtained consists of coin-shaped nanoparticles several hundred nanometers in diameter and less than 50 nm thick. The average thickness of the film was estimated by atomic force microscopy (AFM) to be 140 nm. Humidity sensing properties of the nanostructured material and sensor response times were studied using conductometric and surface acoustic wave (SAW) sensor techniques, revealing reversible signals with good reproducibility and fast response times of about 0.75 s. The applicability of this nanostructured film for construction of rapid humidity sensors was demonstrated. Compared with known complex and expensive methods of synthesizing sophisticated nanostructures for sensor applications, such as physical vapor deposition (PVD) and chemical vapor deposition (CVD), this work presents a relatively simple and inexpensive technique to produce SAW humidity sensor devices with competitive performance characteristics. PMID:21284374

  3. Role of oxygen vacancies in anodic TiO2 thin films

    International Nuclear Information System (INIS)

    Defects play an important role in the electronic and optical properties of amorphous solids in general. Here we present both experimental and theoretical investigations on the nature and origin of defect states in anodic rutile TiO2 thin films (of thickness 5nm to 20nm). There is experimental evidence that the observed gap state at 0.7eV below the edge of conduction-band is due to an oxygen vacancy. For this reason, oxygen vacancies are used in our model. A comparison of the calculated bulk-photoconductivity to photospectroscopy experiment reveals that the films have bulk-like transport properties. On the other hand a fit of the surface density of states to the scanning tunneling microscopy (STM) on the (001) surfaces has suggested a surface defect density of 5% of oxygen vacancies. To resolve this discrepancy, we calculated the dc-conductivity where localization effects are included. Our results show an impurity band formation at about pc=9% of oxygen vacancies. We concluded that the gap states seen in STM are localized and the oxygen vacancies are playing the role of trapping centers (deep levels) in the studied films. (author). 15 refs, 5 figs

  4. Structural, morphological and local electric properties of TiO2 thin films grown by pulsed laser deposition

    International Nuclear Information System (INIS)

    Titanium dioxide (TiO2) thin films were synthesized on (1 0 0) Si substrates by reactive pulsed laser deposition (PLD) technique. A frequency quadrupled Nd : YAG (λ = 266 nm, τFWHM ≅ 5 ns, ν = 10 Hz) laser source was used for the irradiations of metallic Ti targets. The experiments were performed in controlled oxygen atmosphere. Crystallinity, surface morphology and local electric properties of the obtained oxide thin films were investigated by x-ray diffractometry, micro-Raman spectroscopy and current sensing atomic force microscopy. An inter-relation was found between the surface morphology, the crystalline structure and the nano-scale electric properties which open the possibility of synthesizing by the PLD technique TiO2 thin films with tunable functional properties for future applications such as photocatalysts, gas sensors or solar energy converters

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

    International Nuclear Information System (INIS)

    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

  6. C ion-implanted TiO2 thin film for photocatalytic applications

    International Nuclear Information System (INIS)

    Third-generation TiO2 photocatalysts were prepared by implantation of C+ ions into 110 nm thick TiO2 films. An accurate structural investigation was performed by Rutherford backscattering spectrometry, secondary ion mass spectrometry, X-ray diffraction, Raman-luminescence spectroscopy, and UV/VIS optical characterization. The C doping locally modified the TiO2 pure films, lowering the band-gap energy from 3.3 eV to a value of 1.8 eV, making the material sensitive to visible light. The synthesized materials are photocatalytically active in the degradation of organic compounds in water under both UV and visible light irradiation, without the help of any additional thermal treatment. These results increase the understanding of the C-doped titanium dioxide, helpful for future environmental applications

  7. Fabrication of thin film TiO2 nanotube arrays on Co-28Cr-6Mo alloy by anodization

    Science.gov (United States)

    Ni, Jiahua; Frandsen, Christine J.; Noh, Kunbae; Johnston, Gary W.; He, Guo; Tang, Tingting; Jin, Sungho

    2014-01-01

    Titanium oxide (TiO2) nanotube arrays were prepared by anodization of Ti/Au/Ti trilayer thin film DC sputtered onto forged and cast Co-28Cr-6Mo alloy substrate at 400 C. Two different types of deposited film structures (Ti/Au/Ti trilayer and Ti monolayer), and two deposition temperatures (room temperature and 400 C) were compared in this work. The concentrations of ammonium fluoride (NH4F) and H2O in glycerol electrolyte were varied to study their effect on the formation of TiO2 nanotube arrays on a forged and cast Co-28Cr-6Mo alloy. The results show that Ti/Au/Ti trilayer thin film and elevated temperature sputtered films are favorable for the formation of well-ordered nanotube arrays. The optimized electrolyte concentration for the growth of TiO2 nanotube arrays on forged and cast Co-28Cr-6Mo alloy was obtained. This work contains meaningful results for the application of a TiO2 nanotube coating to a CoCr alloy implant for potential next-generation orthopedic implant surface coatings with improved osseointegrative capabilities. PMID:23827596

  8. Microbiology cell-staining wastewater treatment using TiO2 thin films / Tratamiento de agua residual de microbiologa usando pelculas delgadas de TiO2

    Scientific Electronic Library Online (English)

    Jorge A., Fernndez; Magda G., Cardozo; Ana K., Carrascal; Juan C., Salcedo; Aura M., Pedroza; Carlos E., Daza.

    2015-06-01

    Full Text Available La fotocatlisis con UV/TiO2 usando pelculas delgadas fue empleada para el tratamiento de agua residual de microbiologa. Se emple un mtodo simple de sedimentacin por gravedad sobre sustrato de vidrio para la preparacin de las pelculas. El uso de Na4P2O7, microondas y ultrasonido fue estudiado [...] para la disminucin de los granos de TiO2 en las pelculas. Se estableci que el mejor mtodo para disminuir los agregados result de una combinacin de Na4P2O7 (0.01M) y radiacin de microondas (700 W, 20 min). Las pelculas fueron caracterizadas por mtodos microscpicos y espectroscpicos. Se obtuvo la fase anatasa (brecha de energa de 3.2 e.V) y tamaos de grano de 83nm. Los ensayos fotocatalticos utilizando las pelculas de TiO2generaron un 99.5% de decoloracin, 79% de remocin de COT y una inactivacin microbiana total luego de 14 h de tratamiento. No se encontr reactivacin microbiana luego de 48 h de finalizado el tratamiento Abstract in english Microbiology cell-staining wastewater was treated by UV/TiO2 thin films photocatalysis. A simple method of applying gravity sedimentation over glass-type substrate was used for the preparation of the films. The use of Na4P2O7, microwaves, and ultrasounds were studied for decreasing the TiO2 grain si [...] zes on the films. It was established that the best method for reducing grain size resulted from a combination of Na4P2O7 (0.01M) and microwave radiation (700 W, 20 min). The Films were characterized by several microscopic and spectroscopic methods. Anatase phase (gap energy of 3.2 eV) and grain sizes averaging 83 nm were achieved. Photocatalysis tests using TiO2-films showed 99.5 % of decolorization, 79 % TOC abatement, and total microbial inactivation after 14 h of treatment. No bacteria re-growth was found 48 h after the treatment was completed

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

    Indian Academy of Sciences (India)

    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.

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

    Science.gov (United States)

    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. Surface preparation influence on the initial stages of MOCVD growth of TiO2 thin films

    International Nuclear Information System (INIS)

    In situ chemical surface analyses using X-ray photoelectron spectroscopy (XPS), completed by ex situ atomic force microscopy (AFM) analyses, were performed in order to compare the initial stages of MOCVD growth of TiO2 thin films on two different surface types. The first type was a silicon native oxide free hydrogen terminated surface and the second one was a silicon dioxide surface corresponding to a thin layer of 3.5 nm thick in situ thermally grown on silicon substrate. Si(100) was used as substrate, and the growths of TiO2 thin films were achieved with titanium tetraisopropoxide (TTIP) as precursor under a temperature of 675 deg. C, a pressure of 0.3 Pa and a deposition time of 1 h. Whatever the surface is, the deposited titanium amount was globally the same in the two cases. On the contrary, the deposit morphology was different: a covering layer composed of a SiO2 and TiO2 phases mixture on the hydrogen terminated surface, and small TiO2 clusters homogeneously spread on the SiO2 surface

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

    International Nuclear Information System (INIS)

    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

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

    Directory of Open Access Journals (Sweden)

    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 0.36 ?m 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 anataserutile 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. Thickness-dependent photocatalytic performance of nanocrystalline TiO2 thin films prepared by sol-gel spin coating

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

    TiO2 nanocrystalline thin films on soda lime glass have been prepared by solgel 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 UVvis spectrophotometry. The films prepared by titanium tetraisopropoxide (TTIP) as the precursor under pH of 3.5 0.5 and with calcination temperature of 450oC 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

    International Nuclear Information System (INIS)

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

    OpenAIRE

    Isrihetty Senain; Nafarizal Nayan; Hashim Saim

    2010-01-01

    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 w...

  18. Hysteretic current-voltage characteristics in RF-sputtered nanocrystalline TiO2 thin films

    International Nuclear Information System (INIS)

    We have measured the current-voltage characteristics at room temperature of a nanocrystalline TiO2 thin film fabricated by reactive RF-sputtering deposition and sandwiched between ITO (indium-tin-oxide)-buffered glass substrate and an indium top electrode. The I-V characteristics are ohmic for low voltages and become non-linear, hysteretic and asymmetric as the voltage is increased. The system is shown to be well represented by two distinct resistance states in the non-ohmic region. Current transient evolutions were also measured for constant voltage excitations. The resistance is stable in time for voltages in the ohmic regime. In contrast, for voltages in the non-ohmic regime, the resistance has a small variation for a short period of time (order of tens seconds) and then increases with time. For those transients, long characteristic times (on the order of tens of minutes up to hours) were found. The behavior of the system is discussed on the basis of experimental results reported in the literature for similar systems and existing models for electric-field induced resistive switching

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

    Indian Academy of Sciences (India)

    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.

  20. Super-hydrophilic property of vanadium doped TiO2–SiO2 sol–gel derived thin film

    International Nuclear Information System (INIS)

    In this work, vanadium doped TiO2–SiO2 thin films were deposited on glass substrates using the sol–gel dip coating method. Fourier transform infrared spectroscopy was used to investigate the film characteristics. Field Emission Scanning Electron Microscopy and UV–vis spectrophotometer were used to evaluate the film thickness and the optical properties of the thin film. In addition, surface morphology and surface roughness of films were measured with atomic force microscopy analysis. The optical results indicated that vanadium dopant in TiO2–SiO2 changed the absorption edge from ultraviolet to visible light. Water contact angle on the film surfaces was measured by a contact angle analyzer under UV and visible light irradiation. The results indicated that vanadium as a dopant ion had a significant effect on the hydrophilicity property of TiO2–SiO2 thin films. - Highlights: ► Vanadium-doped TiO2–SiO2 thin film deposited on glass substrate by a sol gel process ► Vanadium doping decreased the band gaps of the TiO2–SiO2 thin films. ► Vanadium doping improved the hydrophilicity of TiO2–SiO2 thin films

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

    International Nuclear Information System (INIS)

    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

  2. Structural defects and electronic structure of N-ion implanted TiO2: Bulk versus thin film

    Science.gov (United States)

    Zatsepin, D. A.; Boukhvalov, D. W.; Kurmaev, E. Z.; Zhidkov, I. S.; Gavrilov, N. V.; Korotin, M. A.; Kim, S. S.

    2015-11-01

    Systematic investigation of atomic structure of N-ion implanted TiO2 (thin films and bulk ceramics) was performed by XPS measurements (core levels and valence bands) and first-principles density functional theory (DFT) calculations. In bulk samples experiment and theory demonstrate anion N → O substitution. For the thin films case experiments evidence valuable contributions from N2 and NO molecule-like structures and theoretical modeling reveals a possibility of formation of these species as result of the appearance of interstitial nitrogen defects on the various surfaces of TiO2. Energetics of formation of oxygen vacancies and its key role for band gap reduction is also discussed.

  3. Structural defects and electronic structure of N-ion implanted TiO2: bulk versus thin film

    CERN Document Server

    Zatsepin, D A; Kurmaev, E Z; Zhidkov, I S; Gavrilov, N V; Korotin, M A; Kim, S S

    2015-01-01

    Systematic investigation of atomic structure of N-ion implanted TiO2 (thin films and bulk ceramics) was performed by XPS measurements (core levels and valence bands) and first-principles density functional theory (DFT) calculations. In bulk samples experiment and theory demonstrate anion N->O substitution. For the thin films case experiments evidence valuable contributions from N2 and NO molecule-like structures and theoretical modeling reveals a possibility of formation of these species as result of the appearance of interstitial nitrogen defects on the various surfaces of TiO2. Energetics of formation of oxygen vacancies and its key role for band gap reduction is also discussed.

  4. Laser damage properties of TiO2/Al2O3 thin films grown by atomic layer deposition

    Science.gov (United States)

    Wei, Yaowei; Liu, Hao; Sheng, Ouyang; Liu, Zhichao; Chen, Songlin; Yang, Liming

    2011-08-01

    Research on thin film deposited by atomic layer deposition (ALD) for laser damage resistance is rare. In this paper, it has been used to deposit TiO2/Al2O3 films at 110° C and 280° C on fused silica and BK7 substrates. Microstructure of the thin films was investigated by x-ray diffraction. The laser-induced damage threshold (LIDT) of samples was measured by a damage test system. Damage morphology was studied under a Nomarski differential interference contrast microscope and further checked under an atomic force microscope. Multilayers deposited at different temperatures were compared. The results show that the films deposited by ALD had better uniformity and transmission; in this paper, the uniformity is better than 99% over 100mm Φ samples, and the transmission is more than 99.8% at 1064nm. Deposition temperature affects the deposition rate and the thin film microstructure and further influences the LIDT of the thin films. As to the TiO2/Al2O3 films, the LIDTs were 6.73±0.47J/cm2 and 6.5±0.46J/cm2 at 110° C on fused silica and BK7 substrates, respectively. The LIDTs at 110° C are notably better than 280° C.

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

    International Nuclear Information System (INIS)

    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.

  6. Evolution of structural and optical properties of photocatalytic Fe doped TiO2 thin films prepared by RF magnetron sputtering

    International Nuclear Information System (INIS)

    Undoped and Fe doped TiO2 thin films have been prepared by RF magnetron sputtering. Pure TiO2 thin film exhibited an amorphous-like nature. With increase in iron concentration (00.1 at%), the films exhibited better crystallization to anatase phase . Red shift of absorption edge was observed in the UV-vis transmittance spectra . At higher Fe concentration (0.5 at%), onset of phase transformation to rutile is noticed. Photocatalytic properties of pure and 0.1 at% Fe doped TiO2 thin films were investigated by degradation of methylene blue in UV light, visible light and light from Hg vapor lamp. 70% degradation of methylene blue was observed in the presence of Fe doped film in comparison with 3% degradation in presence of pure TiO2 film when irradiated using visible light for 2 h

  7. Co-doped TiO2 thin films studied by magnetic resonance technique

    International Nuclear Information System (INIS)

    TiO2 thin films with different Co nanoparticle content were prepared by reactive co-sputtering onto Si (100) substrates. The films thicknesses were in range of 200 to 330 nm. Electron probe microanalysis showed the Co content (x) of the Ti1-xCoxO2 samples was 2.2, 3.0, 4.4, 6.5, and 8.5 %. X-ray diffraction measurements revealed polycrystalline Rutile structure of the samples. Magnetization measurements showed hysteresis behavior for all samples with the coercive field in range of 55 - 65 Oe. The saturation magnetization at room temperature ranged from 7 emu/cm''3 (2.2 % Co) to 28 emu/cm''3 (8.5 % Co). X-band (9.5 GHz) Electron Spin Resonance measurements were performed as a function of the sample orientation and temperature. Weak ESR signals that depended on Co content were observed at room temperature. Different contributions to the room temperature spectra were attributed to super-paramagnetic cobalt particles, some ferromagnetic phase in the sample, and paramagnetic impurities in silicon substrate. Very strong temperature dependence of ESR spectra has been observed in all samples. The room temperature signals decreased with cooling, and vanished at lowest temperatures. A very broad signal appeared with cooling, dramatically intensified at about 50-80K, and then decreased at lowest temperature (10K). A kind of phase transition in the temperature behavior of the intensity was observed in the temperature range of 50-60K. We attribute this behavior to unconventional spin-glass-like ordering realized in the system. The results received are important for understanding the tunnel magnetoresistance behavior of such systems

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

    Directory of Open Access Journals (Sweden)

    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.

  9. Reactivity Screening of Anatase TiO2 Nanotube Arrays and Anatase Thin Films: A Surface Chemistry Point of View

    Energy Technology Data Exchange (ETDEWEB)

    Funk, S.; Hokkanen, B.; Nurkic, T.; Goering, J.; Kadossov, E.; Burghaus, Uwe; Ghicov, A.; Schmuki, P.; Yu, Zhongqing; Thevuthasan, Suntharampillai; Saraf, Laxmikant V.

    2008-09-19

    As a reactivity screening we collected thermal desorption spectroscopy (TDS) data of iso-butane, O2, CO2, and CO adsorbed on ordered TiO2 nanotube (TiNTs) arrays. As a reference system iso-butane adsorption on an anatase TiO2 thin film has been considered as well. The as-grown TiNTs are vertically aligned and amorphous. Polycrystalline (poly.) anatase or poly. anatase/rutile mixed nanotubes are formed by annealing confirmed by x-ray diffraction (XRD) and scanning electron microscopy (SEM). The anatase thin film was grown on SrTiO3(001) and characterized by XRD and atomic force microscopy (AFM). Surprisingly, oxygen distinctly interacts with the TiNTs whereas this process is not observed on fully oxidized single crystal rutile TiO2(110). Desorption temperatures of 110-150 K and 100-120 K were observed for CO2 and CO, respectively, on the TiNTs. Variations in the binding energies of the alkanes on TiNTs and anatase thin films also were present, i.e., a structure-activity relationship (SAR) is evident.

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

    Directory of Open Access Journals (Sweden)

    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.

  11. Structural evolution of TiO2 nanocrystalline thin films by thermal annealing and swift heavy ion irradiation

    International Nuclear Information System (INIS)

    The present study probes into the transition from anatase to rutile phase of TiO2 in 100 nm thick nanocrystalline thin films under thermal annealing and swift heavy ion (SHI) irradiation. The films were prepared using sol-gel and spin coating techniques on silicon (100) substrates. The as-deposited films are found to be amorphous by glancing angle x-ray diffraction and Raman spectroscopy. Though thermal annealing is known to cause transformation from anatase to rutile phase of TiO2 in a temperature interval of 700-900 deg. C, in nanoparticle thin films, we found that a sizable volume fraction of anatase still remains even after annealing at 1000 deg. C. Irradiations by 200 MeV Ag ions on the other hand suppressed the anatase phase and almost phase pure rutile TiO2 could be obtained at a fluence of 3x1012 ions cm-2. A mechanism based on the competing effect of grain growth and conversion of anatase to rutile at the grain boundary of the anatase on annealing and conversion of anatase to rutile in the grains of the anatase due to SHI induced thermal spike is proposed to explain the observed result

  12. Structural evolution of TiO2 nanocrystalline thin films by thermal annealing and swift heavy ion irradiation

    Science.gov (United States)

    Rath, H.; Dash, P.; Som, T.; Satyam, P. V.; Singh, U. P.; Kulriya, P. K.; Kanjilal, D.; Avasthi, D. K.; Mishra, N. C.

    2009-04-01

    The present study probes into the transition from anatase to rutile phase of TiO2 in 100 nm thick nanocrystalline thin films under thermal annealing and swift heavy ion (SHI) irradiation. The films were prepared using sol-gel and spin coating techniques on silicon (100) substrates. The as-deposited films are found to be amorphous by glancing angle x-ray diffraction and Raman spectroscopy. Though thermal annealing is known to cause transformation from anatase to rutile phase of TiO2 in a temperature interval of 700-900 C, in nanoparticle thin films, we found that a sizable volume fraction of anatase still remains even after annealing at 1000 C. Irradiations by 200 MeV Ag ions on the other hand suppressed the anatase phase and almost phase pure rutile TiO2 could be obtained at a fluence of 31012 ions cm-2. A mechanism based on the competing effect of grain growth and conversion of anatase to rutile at the grain boundary of the anatase on annealing and conversion of anatase to rutile in the grains of the anatase due to SHI induced thermal spike is proposed to explain the observed result.

  13. Photodegradation of reactive red 222 using TiO2 nanostructured thin films prepared by modified sol-gel method

    Directory of Open Access Journals (Sweden)

    F. Oshani

    2014-11-01

    Full Text Available In this paper, a modified sol-gel method using peroxotitanic acid sol (PTA was applied for the preparation of TiO2 nanostructured thin films on glass plates. The peroxotitanic acid sol was synthesized using titanium isopropoxide, isopropylalchol, H2O and hydrogen peroxide. TiO2 films were then calcined at 500oC and characterized by X-ray diffraction (XRD and scanning electron microscopy (SEM. XRD results showed that increasing the number of coated layers would lead to the formation of anatase phase at high level. Addition of Polyethylene Glycol (PEG on the PTA sol could cause uniform coating without any cracks. The photocatalytic performance of the obtained films was investigated by the photodegradation measurements of Reactive Red 222 (RR222 in a batch reactor. For further investigations the effect of some parameters such as initial RR222 concentration, pH value, hydrogen peroxide addition and temperature on the photocatalytic performance of TiO2 thin films was studies as the important factors. Kinetic study results of this reaction represented that it obeys of was pseudo-first-order model. The degradation of RR22 was enhanced by the addition of optimum amount of hydrogen peroxide. This is due to the increasing amount of the radical hydroxyls.

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

    Science.gov (United States)

    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 intermediates is different on pure TiO2 and Nb-doped TiO2, but cannot explain the overall lower total oxidation rate for the Nb-doped films. Instead the inferior photocatalytic activity in Nb-doped TiO2 is attributed to an enhanced electron-hole pair recombination rate due to Nb=O cluster and cation vacancy formation. PMID:16471666

  15. Development of visible light activated TiO2 thin films on stainless steel via sol spraying with emphasis on microstructural evolution and photocatalytic activity

    Science.gov (United States)

    Momeni, Mansour; Golestani-Fard, Farhad; Saghafian, Hasan; Barati, Nastaran; Khanahmadi, Amirhossein

    2015-12-01

    Visible light activated nitrogen doped TiO2 thin films were developed on 304 stainless steel by sol spraying method using a common painting airbrush. Thin films with different thickness were prepared and calcined at various temperatures from 400 to 600 °C. The samples were studied using ellipsometry, XRD, GIXRD, XPS, DRS, SEM and FESEM. Photocatalytic activities of the films were investigated by measuring their ability to degrade methylene blue solution under visible light irradiation. Results revealed that uniform nanostructured films with a thickness range of 29-150 nm were successfully prepared on stainless steel by sol spraying. Doping nitrogen into TiO2 structure restricted the crystallite growth of anatase phase and reduced the band gap energy to 2.85 eV and therefore, activated TiO2 in visible light region. Increasing calcination temperature not only promoted crack formation in thin films, but also encouraged Fe diffusion from substrate into thin films structure. However, the N doped TiO2 film calcined at 500 °C with a thickness of 150 nm indicated a significant photocatalytic activity in visible light with 22% higher efficiency in comparison with undoped TiO2 film. Development of TiO2 based photocatalytic thin films by a simple method of airbrushing, builds up the hope for industrial scale applications in future.

  16. Electrical and optical properties of the hybrid TiO2 nanocrystals - MEH-PPV thin films

    International Nuclear Information System (INIS)

    Recently, the conjugated polymer-inorganic nanocomposites have been increasingly studied because of their enhanced optical and electronic properties as well as their potential application in developing optoelectronic devices. In this study nanocomposite materials thin films based on poly [2-methoxy-5-(2-ethyl-hexyloxy) - 1,4- phenylene vinylene] (MEH-PPV) and nanocrystalline TiO2 (nc-TiO2) have been fabricated. The photoluminescence (PL) spectra of pure MEN-PPV and nanohybrid films have shown that the excitation at a 377 nm wavelength leads to the strongly enhanced performance in photoluminescent intensity due to the compositions of TiO2 component. Current-voltage (I-V) characteristics of multi-layer device Al/ /MEH-PPV; nc-TiO2/ /PEDOT: PSS/ /ITO/ /glass were investigated. the results show that the hybrid MEH-PPV: nc-TiO2 materials with high concentrations of TiO2 (>25 %) can be expected to be a good candidate for photovoltaic solar cell applications whereas hose with lower concentrations of TiO2 are more suitable for organic light-emitting diodes (OLEDs). (author)

  17. Properties of TiO2 thin films and a study of the TiO2-GaAs interface

    Science.gov (United States)

    Chen, C. Y.; Littlejohn, M. A.

    1977-01-01

    Titanium dioxide (TiO2) films prepared by chemical vapor deposition were investigated in this study for the purpose of the application in the GaAs metal-insulator-semiconductor field-effect transistor. The degree of crystallization increases with the deposition temperature. The current-voltage study, utilizing an Al-TiO2-Al MIM structure, reveals that the d-c conduction through the TiO2 film is dominated by the bulk-limited Poole-Frenkel emission mechanism. The dependence of the resistivity of the TiO2 films on the deposition environment is also shown. The results of the capacitance-voltage study indicate that an inversion layer in an n-type substrate can be achieved in the MIS capacitor if the TiO2 films are deposited at a temperature higher than 275 C. A process of low temperature deposition followed by the pattern definition and a higher temperature annealing is suggested for device fabrications. A model, based on the assumption that the surface state densities are continuously distributed in energy within the forbidden band gap, is proposed to interpret the lack of an inversion layer in the Al-TiO2-GaAs MIS structure with the TiO2 films deposited at 200 C.

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

    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

  20. Determination of thermo-optic properties of atomic layer deposited thin TiO2 films for athermal resonant waveguide gratings by spectroscopic ellipsometry

    Science.gov (United States)

    Saleem, Muhammad Rizwan; Ali, Rizwan; Honkanen, Seppo; Turunen, Jari

    2014-05-01

    We report on variation in the refractive index of amorphous and isotropic TiO2 thin films grown by Atomic Layer Deposition (ALD) in nano optical devices. ALD-TiO2 films of thicknesses ALD-TiO2 films with thicknesses > 200 nm show positive TOC due to the predominance of TiO2 thickness over the very thin surface porosity region. The negative TOC of thin TiO2 films was controlled by depositing thin ALD-Al2O3 diffusion barrier films that showed impermeable behavior to block the evaporation of adsorbed water molecules on TiO2 surfaces in thermal environments. This approach turns negative sign of TOC of TiO2 thin films to positive one which is necessary to stabilize the central resonance peak of a guided mode resonance filter (GMRF). The ALD-TiO2 and ALDAl2O3 bi-layer stack was modeled by VASE analysis of spectroscopic ellipsometry using Cauchy Model to extract refractive indices at various temperatures, measured at two different angle of incidence (65° and 75°), covering a wide spectral range 380 TiO2 films were calculated from ellipsometric measured data using Lorentz-Lorenz relation.

  1. Chemical vapor deposition and characterization of nitrogen doped TiO2 thin films on glass substrates

    International Nuclear Information System (INIS)

    Photocatalytically active, N-doped TiO2 thin films were prepared by low pressure metalorganic chemical vapor deposition (MOCVD) using titanium tetra-iso-propoxide (TTIP) as a precursor and NH3 as a reactive doping gas. We present the influence of the growth parameters (temperature, reactive gas phase composition) on the microstructural and physico-chemical characteristics of the films, as deduced from X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS) and ultra-violet and visible (UV/Vis) spectroscopy analysis. The N-doping level was controlled by the partial pressure ratio R = [NH3]/[TTIP] at the entrance of the reactor and by the substrate temperature. For R = 2200, the N-doped TiO2 layers are transparent and exhibit significant visible light photocatalytic activity (PA) in a narrow growth temperature range (375-400 oC). The optimum N-doping level is approximately 0.8 at.%. However, the PA activity of these N-doped films, under UV light radiation, is lower than that of undoped TiO2 films of comparable thickness.

  2. Effect of electrode type in the resistive switching behaviour of TiO2 thin films

    International Nuclear Information System (INIS)

    The influence of the electrode/active layer on the electric-field-induced resistance-switching phenomena of TiO2-based metal-oxide-metal devices (MOM) is studied. TiO2 active layers were fabricated by the reactive rf-sputtering technique and devices were made by sandwiching between several metal electrodes. Three different MOM devices were made, according with the junction type formed between the electrode and the TiO2 active layer, those where Ohmic-Ohmic, Ohmic-Schottky and Schottky-Schottky. The junction type was tested by electrical I-V measurements. It was found that MOM devices made with the Ohmic-Ohmic combination did not show any resistive switching behaviour in contrast with devices made with Ohmic-Schottky and Schottky-Schottky combinations. From a detailed analysis of the I-V curves it was found that transport characteristics are Ohmic for the low-resistance state for all the contacts combinations of the MOM devices, whereas in the high-resistance state it depends on contact combinations and can be identified as Ohmic, Schottky and Poole-Frenkel type. These conduction mechanisms in the low- and high-resistance states suggest that formation and rupture of conducting filaments through the film oxide is the mechanism responsible for the resistance switching.

  3. Effect of electrode type in the resistive switching behaviour of TiO2 thin films

    Science.gov (United States)

    Hernández-Rodríguez, E.; Márquez-Herrera, A.; Zaleta-Alejandre, E.; Meléndez-Lira, M.; de la Cruz, W.; Zapata-Torres, M.

    2013-01-01

    The influence of the electrode/active layer on the electric-field-induced resistance-switching phenomena of TiO2-based metal-oxide-metal devices (MOM) is studied. TiO2 active layers were fabricated by the reactive rf-sputtering technique and devices were made by sandwiching between several metal electrodes. Three different MOM devices were made, according with the junction type formed between the electrode and the TiO2 active layer, those where Ohmic-Ohmic, Ohmic-Schottky and Schottky-Schottky. The junction type was tested by electrical I-V measurements. It was found that MOM devices made with the Ohmic-Ohmic combination did not show any resistive switching behaviour in contrast with devices made with Ohmic-Schottky and Schottky-Schottky combinations. From a detailed analysis of the I-V curves it was found that transport characteristics are Ohmic for the low-resistance state for all the contacts combinations of the MOM devices, whereas in the high-resistance state it depends on contact combinations and can be identified as Ohmic, Schottky and Poole-Frenkel type. These conduction mechanisms in the low- and high-resistance states suggest that formation and rupture of conducting filaments through the film oxide is the mechanism responsible for the resistance switching.

  4. Angle dependence of the O K edge absorption spectra of TiO2 thin films with preferential texture

    International Nuclear Information System (INIS)

    O K and Ti L2,3 edge X-ray absorption spectra have been recorded for TiO2 thin films (∼100 nm thickness) prepared by ion beam induced CVD at room temperature. The as prepared films were amorphous but they crystallize into the anatase structure of TiO2 after annealing at T>650 K. In the amorphous films, the magnitude of the crystal field, determined from the evaluation of the spectra, was smaller than in the well crystallized anatase samples. In these latter samples the O K edge spectra show a strong dependence on the angle of incidence of the radiation with respect to the sample surface. This dependence rises some concerns about the use of the O K edge spectra of oxide materials for a universal 'fingerprint' characterization of thin films. A preliminary theoretical evaluation of the evolution of the t2g/eg intensity ratio with the relative orientation of the electric field of the radiation and the surface normal of the samples is carried out. For this evaluation, the texture of the thin film (i.e. the preferential growth of certain crystallographic planes parallel to the surface) and the existence of surface modifications of the environment around the Ti are taken into account

  5. Growth of TiO2 thin films by AP-MOCVD on stainless steel substrates for photocatalytic applications

    OpenAIRE

    Duminica, Florin-Daniel; Maury, Francis; Hausbrand, R.

    2007-01-01

    TiO2 thin films were deposited under atmospheric pressure by MOCVD in the temperature range 400-600 C on stainless steel and Si(100) substrates. Titanium tetraisopropoxide (TTIP) was used as Ti and O source. Single-phased anatase and bi-phased (anatase/rutile) coatings with controlled composition have been deposited depending on the temperature and the TTIP mole fraction. The films grown on stainless steel at low temperature (b420 C) and low TTIP mole fraction (b10?4) are constituted of pur...

  6. Effects of TiO2 Interlayers on the Optical Switching of VO2 Thin Films Grown by Sol-Gel Process

    Directory of Open Access Journals (Sweden)

    ZHANG Yu-Bo, HUANG Wan-Xia, SONG Lin-Wei, YAN Jia-Zhen, SHI Qi-Wu, ZHANG Yang

    2013-02-01

    Full Text Available Thermochromic VO2 and VxW1-xO2 films were deposited on TiO2/mica substrates. The TiO2/mica substrates were fabricated via Sol-Gel process, and the hydrophilicity of the TiO2/mica substrate was improved under UV light irradiated. The V2O5 sol was deposited on the TiO2/mica substrate by the spin coating method, and then it was annealed. SEM and XRD analysis were applied to analyze the morphology, phases and microstructure of the films. FTIR was used to study the thermochromic properties. The results suggest that VO2/TiO2 grow preferentially along single orientation. VxW1-xO2/TiO2 composite film is impossible to fabricate single orientation films. TiO2 interlayers are favorable to compact the VO2 thin films and reduce the transition temperature. It will make the hysteresis width of VxW1-xO2/TiO2 composite film reduce to about 4¡䟰articularly.

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

    International Nuclear Information System (INIS)

    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

  8. Solution processed thin films of Nb-doped TiO2 nanoparticles as hole blocking layer for organic solar cells

    International Nuclear Information System (INIS)

    In this study, Nb-doped TiO2 nanoparticles were synthesized by sol–gel method with controlled doping ratios up to 6 mol%. Catalyzed by p-toluene sulfonic acid, alkoxide precursors of Ti and Ni were stabilized by acetylacetone ligand, and converted to the organically modified nanoparticles which were well dispersible in alcohols. Transmission electron microscopy and X-ray diffraction measurements revealed that TiO2 nanoparticle possesses anatase morphologies, and the doping ratios were confirmed by X-ray photoelectron spectroscopy. Uniform thin films of Nb-doped TiO2 were obtained by spin coating dilute alcohol dispersions of Nb-doped nanoparticles. Ellipsometric characterizations were carried out for the as-coated film and the sintered film as well to characterize the indices of refraction, and atomic force microscopy showed subnanometer-scale roughness of Nb-doped films. Owing to the improved roughness via doping, Nb-doped TiO2 thin films exhibited enhanced solar cell efficiencies when used as hole-blocking layer of organic hetero-junction solar cell. - Highlights: • We synthesize Nb-doped TiO2 nanoparticles by sol–gel method with up to 6 mol% doping. • We disperse nanoparticles in alcohols without aggregation. • Particle size decreases by high Nb doping. • Uniform thin films of Nb-doped TiO2 are obtained by spin coating. • Thin films used as hole blocking layer in organic solar cell enhance cell efficiency

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

    International Nuclear Information System (INIS)

    This paper reports a systematic analysis of the mechanical properties of nanocolumnar TiO2 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

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

    Science.gov (United States)

    Nurfani, Eka; Sutjahja, Inge M.; Winata, Toto; Rusydi, Andrivo; Darma, Yudi

    2015-09-01

    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. Due to a processing error by AIP Publishing, an incorrect version of the above article was published on 30 September 2015 that omitted the name of author Toto Winata. AIP Publishing apologizes for this error. All online versions of the article were corrected on 7 October 2015. The author names and affiliations appear correctly above.

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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.

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

    Science.gov (United States)

    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.

  14. Gamma Radiation Monitoring Through Thin Film of ClAlPc Doped With TiO2

    International Nuclear Information System (INIS)

    Chloroaluminum phthalocyanine (ClAlPc) synthesized by adopting focused microwave synthesis approach was doped with nanocrystalline TiO2 (5% by weight) and developed into the thin film sandwiched device having ITO/ClAlPc:TiO2/Ag Schottky configuration by spin coating technique covering 1 cm2 as an active area. The so fabricated device having initial dark current of the order of 0.2 5 m A was exposed to variable dose of gamma radiation ranging from lcGy to 10 Gy at a dose rate of 1 Gy/hour. The experimental observation reveals the generation of localized traps leading to structural disorder within the solid material. Doping with TiO2 enhances the surface area of the film which in tern improves sensitivity of device to wider dose rage. Exposure of the device to variable dose of gamma radiation imparts decrease in forward bias current and capacitance characteristics with increase in radiation dose. Also, absorbance characteristics of the Al Pc: TiO2 was analyzed before and after exposure to radiation which reveals that absorbance decreases with radiation dose leading to decrease in optical band gap

  15. Gamma Radiation Monitoring Through Thin Film of ClAlPc Doped With TiO2

    Science.gov (United States)

    Roy, M. S.; Gautam, A. K.; Kumar, M.; Prasad, N.; Janu, Y.; Deol, Y. S.; Mishra, R. K.; Choudhary, G. R.; Sadh, A. K.

    2008-04-01

    Chloroaluminum phthalocyanine (ClAlPc) synthesized by adopting focused microwave synthesis approach was doped with nanocrystalline TiO2 (5% by weight) and developed into the thin film sandwiched device having ITO/ClAlPc:TiO2/Ag Schottky configuration by spin coating technique covering 1 cm2 as an active area. The so fabricated device having initial dark current of the order of 0.2 5 m A was exposed to variable dose of gamma radiation ranging from lcGy to 10 Gy at a dose rate of 1 Gy/hour. The experimental observation reveals the generation of localized traps leading to structural disorder within the solid material. Doping with TiO2 enhances the surface area of the film which in tern improves sensitivity of device to wider dose rage. Exposure of the device to variable dose of gamma radiation imparts decrease in forward bias current and capacitance characteristics with increase in radiation dose. Also, absorbance characteristics of the Al Pc: TiO2 was analyzed before & after exposure to radiation which reveals that absorbance decreases with radiation dose leading to decrease in optical band gap.

  16. TiO2 anatase thin films deposited by spray pyrolysis of an aerosol of titanium diisopropoxide

    International Nuclear Information System (INIS)

    Titanium dioxide thin films were deposited on crystalline silicon (100) and fused quartz substrates by spray pyrolysis (SP) of an aerosol, generated ultrasonically, of titanium diisopropoxide. The evolution of the crystallization, studied by X-ray diffraction (XRD), atomic force (AFM) and scanning electron microscopy (SEM), reflection and transmission spectroscopies, shows that the deposition process is nearly close to the classical chemical vapor deposition (CVD) technique, producing films with smooth surface and good crystalline properties. At deposition temperatures below 400 deg. C, the films grow in amorphous phase with a flat surface (roughness∼0.5 nm); while for equal or higher values to this temperature, the films develop a crystalline phase corresponding to the TiO2 anatase phase and the surface roughness is increased. After annealing at 750 deg. C, the samples deposited on Si show a transition to the rutile phase oriented in (111) direction, while for those films deposited on fused quartz no phase transition is observed

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

    Science.gov (United States)

    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.

  18. Nanostructured nitrogen and carbon codoped TiO2 thin films: Synthesis, structural characterization and optoelectronic properties

    Science.gov (United States)

    Ruzybayev, Inci

    TiO2 is widely used in applications like photocatalysis, sensors, solar cells, and memory devices because it is inexpensive, abundant, nontoxic and stable in aqueous solution. Another exciting application where TiO 2 has the potential to be a very useful catalyst is the clean hydrogen generation using solar radiation. Energy consumption is increasing every year and, as a result, renewable and sustainable alternative energy sources are becoming increasingly important. Therefore, clean hydrogen generation research is becoming more and more important. This study aims at the preparation and characterization of nitrogen and carbon (N-C) codoped TiO2 photoanode material that could potentially be used in photoelectrochemical cells for hydrogen generation. The solar spectrum peaks around 500 nm (2.48 eV) which is in the visible part of the spectrum. The photoanode material to be used for solar hydrogen generation should absorb visible light photons to yield high efficiency. The challenge with TiO2 is that the wide band gap (3.00--3.20 eV) absorbs only ultra-violet (UV) photons and only a small percentage of the solar spectrum is in the UV range. There are various ways to overcome the challenge of sensitizing the material to visible light absorption and this study focuses on one of the most promising ways: band modification of TiO2 by N-C codoping. The role of pure oxygen pressure on pulsed laser deposited N-C codoped TiO2 films were investigated. At low pressures rutile phase of TiO2 was dominant and a microstructure with densely packed grains was obtained. However, at high pressures anatase phase became dominant and columnar structure was favored. Therefore, the anatase-rutile phase ratio as well as the microstructure of the films can be controlled by adjusting oxygen pressure and introducing N and C into the TiO2 matrix. Optimized oxygen pressure and higher doping concentrations yielded films with more effective absorption in the visible region. The preparation and characterization of pulsed laser deposited N-C codoped TiO2 thin films were investigated for dopant incorporation using N2 and CH4 gases. Polycrystalline anatase structured films were obtained. A 2 theta shift of the anatase (101) X-ray diffraction main peak towards lower values indicated carbon incorporation into the lattice. N incorporation was confirmed with observed Ti-N bonds using X-ray photoelectron spectroscopy. Optical data showed significant reduction, approximately 1.00 eV, of the band gap. The reduction of the band gap allowed the photons in the visible part of the solar spectrum to be absorbed. Through a collaborative work with scientists at Brookhaven National Laboratory and Yonsei University, precise modeling of the electronic structure of N-C codoped TiO2 films were carried out to reveal the underlying physics of band gap reduction. Experimental results were compared with first-principle density functional theory calculations. Hard X-ray photoelectron spectroscopy showed that O, N and C 2p states overlapped effectively and shifts in the valence band maximum towards the Fermi level were observed. Optical band gap results showed that N-C codoping is an effective route for band gap reduction in TiO2. Comparison of the measured valence band structure with theoretical photoemission density of states further revealed C substitution on the Ti site and N substitution on the O site. Finally, films grown using radio frequency (rf) magnetron sputtering were compared with the pulsed laser deposited films. Sputtered N-C codoped TiO2 films showed phase transformation from anatase to rutile at constant argon pressure with increasing doping concentration. Moreover, with slow-rate N-C codoping of TiO2, a texturing effect was observed in X-ray diffraction scans such that anatase (004) Bragg reflection plane became more favored over anatase (101). Optical band gap was reduced but the reduction was not as significant as in the films prepared with the pulsed laser deposition method. Electrochemical methods were applied in the photoelectrochemical cell and the sample prep

  19. Highly efficient photoelectrochemical performance of SrTiO3/TiO2 heterojunction nanotube array thin film

    International Nuclear Information System (INIS)

    SrTiO3TiO2 heterojunction thin-film nanotube arrays (SNTs, the average inner diameter is about 50 nm) was fabricated via electrochemical anodization followed by a hydrothermal treatment. The photo-to-current conversion properties and the photoelectrochemical performance for cathodic protection of carbon steel in 0.5 M of sodium chloride solution under white light illumination were investigated. The results showed that the highly ordered nanotube arrays could provide very excellent cathodic protection for carbon steel under white light irradiation.

  20. Degradation of gas-phase trichloroethylene over thin-film TiO2 photocatalyst in multi-modules reactor

    International Nuclear Information System (INIS)

    The present paper examined the photocatalytic degradation (PCD) of gas-phase trichloroethylene (TCE) over thin-film TiO2. A large-scale treatment of TCE was carried out using scale-up continuous flow photo-reactor in which nine reactors were arranged in parallel and series. The parallel or serial arrangement is a significant factor to determine the special arrangement of whole reactor module as well as to compact the multi-modules in a continuous flow reactor. The conversion of TCE according to the space time was nearly same for parallel and serial connection of the reactors.

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

    Czech Academy of Sciences Publication Activity Database

    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

  2. Characterization of n-type and p-type semiconductor gas sensors based on NiOx doped TiO2 thin films

    International Nuclear Information System (INIS)

    This work presents the development of n-type and p-type gas-sensitive materials from NiOx doped TiO2 thin films prepared by ion-assisted electron-beam evaporation. TiO2 gas-sensing layers have been deposited over a wide range of NiOx content (0-10 wt.%). The material analysis by atomic force microscopy, X-ray photoemission spectroscopy, and X-ray diffraction suggests that NiOx doping does not significantly affect surface morphology and Ni element may be a substitutional dopant of the TiO2 host material. Electrical characterization shows that NiOx content as high as 10% wt. is needed to invert the n-type conductivity of TiO2 into p-type conductivity. There are notable gas-sensing response differences between n-type and p-type NiOx doped TiO2 thin film. The responses toward all tested reducing gases tend to increase with operating temperature for the n-type TiO2 films while the response decreases with temperature for p-type TiO2 film. In addition, the p-type NiOx doping results in the significant response enhancement toward tested reducing gases such as acetone and ethanol at low operating temperature of 300 deg. C

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

    International Nuclear Information System (INIS)

    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.

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

    International Nuclear Information System (INIS)

    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.

  5. Photocatalytically active TiO2 thin films produced by surfactant-assisted sol-gel processing

    International Nuclear Information System (INIS)

    Thin TiO2 films were prepared from a titanium isopropoxide precursor by sol-gel processing with or without various nonionic surfactant molecules (Brij 56, Triton X-100 or Pluronic F-127). The photocatalytic efficiency of the transparent films obtained by a dip-coating technique was found to depend strongly on the use of and type of surfactant added. Titania/Pluronic sols resulted in homogeneous and crack-free TiO2 anatase films with a thickness as much as 300 nm after one dipping and heat-treatment (500 deg. C) cycle. Optical properties of the films were characterized by UV-Vis spectroscopy and crystalline structures by X-ray diffraction. A surfactant-assisted sol-gel process retarded crystallization of the anatase titania films, which resulted in smaller grain sizes (down to 10 nm) and presumably a larger active surface area. The morphology of the film surfaces as obtained by SEM techniques could be also correlated with the results of our photodegradation studies. The photocatalytic activity of the films was enhanced by first coating the glass substrate with a SiO2 protective layer prior to the deposition of the titania film. For our in situ studies of photodegradation we chose the monoazo dye Plasmocorinth B as a model compound as it is stable under environmental conditions and its degradation products are not coloured. The highest photobleaching rate was found for films deposited from the sol with addition of the Pluronic surfactant and it was almost twice as high as that for films deposited from sols without the surfactant

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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

  8. Photoluminescence and surface photovoltage studies of defects at nanoscale surfaces and interfaces in thin films of ZnO, TiO2 and diamond

    Science.gov (United States)

    Nemashkalo, Anastasiia

    The electronic properties of nanomaterials are greatly affected by their surfaces, which often contain significant numbers of defects that induce localized bandgap states. These localized states may have a significant impact on a material's optical absorption spectrum, conductivity, and charge dynamics --- characteristics that are important in applications. The focus of the present work was on the surface defect properties of thin films of titanium dioxide, zinc oxide and diamond. Experimental methods sensitive to the spectral signatures of surface and bulk defects (photoluminescence and surface photovoltage spectroscopy were used to estimate the electronic structure of each of these materials. Band diagrams of TiO2, TiO2/Au, TiO 2/Ag, and TiO2/ZrO2 thin films have been obtained. The results suggest that all TiO2-based films contain a significant number of native defect-related gap states. In addition, a new energy level at ~ 1.8 eV was detected in TiO2/Ag and specifically attributed to the added Ag. The electronic structure of TiO2/Au did not differ significantly from that of TiO2. After the addition of zirconium, the number of native defect-related states increased. The TiO2-based samples were also subjected to low energy Ti+-irradiation followed by similar gap structure studies. The results are discussed relative to photocatalytic applications of the studied materials. The optoelectronic properties of homoepitaxial ZnO thin films synthesized by the atomic layer deposition method were also studied. The films were grown at different temperatures in order to study the effects of growth conditions on the defect concentration. Surface photovoltage and temperature-dependent photoluminescence studies showed that our ZnO thin films have low concentrations of defects and excellent crystallinity. The growth temperature, however, has only a slight effect on the overall quality of the films. Lastly, diamond thin films grown by the chemical vapor deposition method were studied. The films were doped with different amounts of boron and some were gamma irradiated. The mechanism for conductivity in diamond thin films with different boron concentrations was also studied. The impact of gamma irradiation on the films' conductive properties was investigated.

  9. In-situ and ex-situ characterization of TiO2 and Au nanoparticle incorporated TiO2 thin films for optical gas sensing at extreme temperatures

    Science.gov (United States)

    Ohodnicki, Paul R.; Wang, Congjun; Natesakhawat, Sittichai; Baltrus, John P.; Brown, Thomas D.

    2012-03-01

    Sensor technologies that can operate under extreme conditions including high temperatures, high pressures, highly reducing and oxidizing environments, and corrosive gases are needed for process monitoring and control in advanced fossil energy applications. Sensor technologies based on optical waveguide-based techniques are highly attractive for passive, embedded, and remote sensing. A critical enabling technology for optical waveguide sensors is the development of advanced optical thin film coatings which have a desired set of optical properties that change in a rapid, selective, and sensitive manner to a particular quantity of interest. TiO2 and Au nanoparticle incorporated TiO2 nanocomposite thin films were prepared through sol-gel deposition techniques and their respective optical responses to a 4% H2/N2 mixture were investigated in the visible / near-IR range of 400-1000 nm. A tendency for Au nanoparticles to occupy special sites on the TiO2 microstructure, such as grain boundaries, twin boundaries, and triple points is rationalized in terms of basic surface energy arguments. The Au / TiO2 nanocomposite films showed a useful optical response due to a reversible, rapid, and repeatable shift in the localized surface plasma resonance peak of Au nanoparticles at a temperature of 650 C and 850 C. In contrast, high temperature exposure of TiO2 films to reducing gases at 850 C resulted in the growth of abnormally large grains or "hillocks" that protruded from the sample surface and resulted in light scattering and an irreversible decrease in transmission at short wavelengths. The origin of the observed optical response of Au / TiO2 nanocomposite films is discussed in the context of work by prior investigators in the Au / yttria-stabilized Zirconia (YSZ) system and needs for future research in this area is highlighted.

  10. Structural and electrical characteristics of ZrO2-TiO2 thin films by sol-gel method

    International Nuclear Information System (INIS)

    In this paper, we investigated electrical properties and microstructures of ZrTiO4 (ZrO2-TiO2) thin films prepared by the sol-gel method on ITO substrates at different annealing temperatures. All films exhibited ZrTiO4 (1 1 1) and (1 0 1) orientations perpendicular to the substrate surface, and the grain size increased with increase in the annealing temperature. A low leakage current density of 2.06 x 10-6 A/cm2 was obtained for the prepared films. Considering the primary memory switching behavior of ZrTiO4, ReRAM based on ZrTiO4 shows promise for future nonvolatile memory applications.

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

    Directory of Open Access Journals (Sweden)

    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.

  12. Ab-initio calculations of the Optical band-gap of TiO2 thin films

    CERN Document Server

    Wunderlich, W; Tanemura, M; Tanemura, S; Jin, P; Kaneko, K; Terai, A; Nabatova-Gabin, N; Belkada, R; Wunderlich, Wilfried; Miao, Lei; Tanemura, Masaki; Tanemura, Sakae; Jin, Ping; Kaneko, Kenji; Terai, Asuka; Nabatova-Gabin, Nataliya; Belkada, Rachid

    2004-01-01

    Titanium dioxide has been extensively studied in recent decades for its important photocatalytic application in environmental purification. The search for a method to narrow the optical band-gap of TiO2 plays a key role for enhancing its photocatalytic application. The optical band gap of epitaxial rutile and anatase TiO2 thin films deposited by helicon magnetron sputtering on sapphire and on SrTiO3 substrates was correlated to the lattice constants estimated from HRTEM images and SAED. The optical band-gap of 3.03 eV for bulk-rutile increased for the thin films to 3.37 on sapphire. The band gap of 3.20 eV for bulk-anatase increases to 3.51 on SrTiO3. In order to interpret the optical band gap expansion for both phases, ab-initio calculations were performed using the Vienna ab-initio software. The calculations for rutile as well anatase show an almost linear increase of the band gap width with decreasing volume or increasing lattice constant a. The calculated band gap fits well with the experimental values. T...

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

    International Nuclear Information System (INIS)

    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.

  14. A micro oxygen sensor based on a nano sol-gel TiO2 thin film.

    Science.gov (United States)

    Wang, Hairong; Chen, Lei; Wang, Jiaxin; Sun, Quantao; Zhao, Yulong

    2014-01-01

    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 ?m 350 ?m 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. PMID:25192312

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    Aytug, Tolga; Bogorin, Daniela F.; Paranthaman, Parans M.; Mathis, John E.; Simpson, John T.; Christen, David K.

    2014-06-01

    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.

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

    Science.gov (United States)

    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

  18. Synthesis and characterization of beta barium borate thin films obtained from the BaO-B2O3-TiO2 ternary system

    International Nuclear Information System (INIS)

    This work reports on the synthesis and the structural and optical characterization of beta barium borate (?-BBO) thin films containing 4, 8 and 16 mol% of titanium oxide (TiO2) deposited on fused silica and silicon (0 0 1) substrates using the polymeric precursor method. The thin films were characterized by X-ray diffraction, Raman spectroscopy, atomic force microscopy and scanning electron microscopy techniques. The optical transmission spectra of the thin films were measured over a wavelength range of 800-200 nm. A decrease was observed in the band gap energy as the TiO2 content was raised to 16 mol%. Only the ?-BBO phase with a preferential orientation in the (0 0 l) direction was obtained in the sample containing 4 mol% of TiO2 and crystallized at 650 deg. C for 2 h

  19. High tunability (Ba,Sr)TiO3 thin films grown on atomic layer deposited TiO2 and Ta2O5 buffer layers

    Science.gov (United States)

    Kim, Il-Doo; Tuller, Harry L.; Kim, Hyun-Suk; Park, Jin-Seong

    2004-11-01

    In this letter, we report on increased tunability of Ba0.6Sr0.4TiO3 (BST) thin films by use of Ta2O5 and TiO2 films as buffer layers between BST and Si substrates. Ta2O5 and TiO2 buffer layers were grown by atomic layer deposition (ALD) onto Si substrates followed by pulsed laser deposition of Ba0.6Sr0.4TiO3 thin films onto the buffer layers. The randomly oriented BST films deposited on TiO2/Si substrates exhibited a broader grain size distribution than the (110) textured BST films grown on Ta2O5/Si substrates. At an applied voltage of 10 V, the BST films grown on Ta2O5/Si and TiO2/Si substrates showed much enhanced tunability values of 53.1% and 72.9%, respectively, as compared to the 20.7% value obtained with BST films grown on MgO single crystal substrates. Successful integration of BST low voltage microwave tunable devices onto Si substrates thus appears possible with the aid of ALD grown Ta2O5 or TiO2 buffer layers.

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

    International Nuclear Information System (INIS)

    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.

  1. Photocatalytic thin films containing TiO2:N nanopowders obtained by the layer-by-layer self-assembling method

    International Nuclear Information System (INIS)

    In this work, TiO2-N powders were synthesized by high-energy ball milling, using commercial titanium dioxide (TiO2) in the anatase phase and urea to introduce nitrogen into TiO2 in order to enhance their photocatalytic properties in the visible spectral region. Several samples were prepared by milling a mixture of TiO2-urea during 2, 4, 8, 12 and 24 h and characterized by spectroscopic and analytical techniques. X-ray diffraction (XRD) results showed the coexistence of anatase and high-pressure srilankite TiO2 crystalline phases in the samples. Scanning electron microscopy (SEM) revealed that the grain size of the powder samples decreases to 200 nm at 24 h milling time. UV-Vis diffuse reflectance spectroscopic data showed a clear red-shift in the onset of light absorption from 387 to 469 nm as consequence of nitrogen doping in the samples. The photocatalytic activity of the TiO2-N samples was evaluated by methylene blue degradation under visible light irradiation. It was found that TiO2-N samples had higher photocatalytic activity than undoped TiO2 samples, which could be assigned to the effect of introducing N atoms and XPS results confirm it. Using polyethylenimine (PEI), transparent thin films of TiO2-N nanoparticles were prepared by layer-by-layer self assembly method. UV-visible spectrophotometry was employed in a quantitative manner to monitor the adsorbed mass of TiO2 and PEI after each dip cycle. The adsorption of both TiO2 and PEI showed a saturation dip time of 15 min.

  2. Correlation between microstructure and optical properties of nano-crystalline TiO2 thin films prepared by sol-gel dip coating

    International Nuclear Information System (INIS)

    Titanium dioxide thin films have been prepared from tetrabutyl-orthotitanate solution and methanol as a solvent by sol-gel dip coating technique. TiO2 thin films prepared using a sol-gel process have been analyzed for different annealing temperatures. Structural properties in terms of crystal structure were investigated by Raman spectroscopy. The surface morphology and composition of the films were investigated by atomic force microscopy (AFM). The optical transmittance and reflectance spectra of TiO2 thin films deposited on silicon substrate were also determined. Spectroscopic ellipsometry study was used to determine the annealing temperature effect on the optical properties and the optical gap of the TiO2 thin films. The results show that the TiO2 thin films crystallize in anatase phase between 400 and 800 deg. C, and into the anatase-rutile phase at 1000 deg. C, and further into the rutile phase at 1200 deg. C. We have found that the films consist of titanium dioxide nano-crystals. The AFM surface morphology results indicate that the particle size increases from 5 to 41 nm by increasing the annealing temperature. The TiO2 thin films have high transparency in the visible range. For annealing temperatures between 1000 and 1400 deg. C, the transmittance of the films was reduced significantly in the wavelength range of 300-800 nm due to the change of crystallite phase and composition in the films. We have demonstrated as well the decrease of the optical band gap with the increase of the annealing temperature.

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

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    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.

  5. The Effects of Cu-doped TiO2 Thin Films on Hyperplasia, Inflammation and Bacteria Infection

    Directory of Open Access Journals (Sweden)

    Linhua Li

    2015-11-01

    Full Text Available In the present work, different concentrations of Cu ion (1, 2, 5 and 10 wt % were doped in the TiO2 film by a sol-gel method and dip coating process. The morphology of the Cu-doped TiO2 films were characterized by scanning electron microscopy (SEM and the results showed that the doped Cu made no change to the TiO2 films. The nitric oxide (NO release experiment showed that these Cu-doped surfaces showed the ability of catalytic decomposition of exogenous donor S-nitroso-N-acetyl-penicillamine (SNAP to generate (NO. Based on fluorescence analysis and CCK-8 quantitative results, such films had the ability to inhibit smooth muscle cells adhesion, proliferation and migration with SNAP in vitro. The macrophage adhesion assay and anti-bacterial test proved that such Cu-doped TiO2 films also possessed anti-inflammatory and anti-bacterial abilities. All the abilities above showed positive correlation with the amounts of the doped Cu. This study suggested that the Cu-doped TiO2 films were capable of generating physiological levels of NO in the presence of endogenous donor S-nitrosothiols (RSNO, endowing the TiO2 films with anti-hyperplasia, anti-inflammatory and anti-bacterial abilities.

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

    International Nuclear Information System (INIS)

    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

  7. Photocatalytic Properties of TiO2 Thin Films Modified with Ag and Pt Nanoparticles Deposited by Gas Flow Sputtering.

    Science.gov (United States)

    Maicu, M; Glöss, D; Frach, Peter; Hecker, D; Gerlach, G; Córdoba, José M

    2015-09-01

    In this work, a gas flow sputtering (GFS) process which allows the production and deposition of metal nanoparticles (NPs) in a vacuum environment is described. Aim of the study is to prove the potential of this technology for the fabrication of new TiO2 films with enhanced photocatalytic properties. For this purpose, Ag and Pt NPs have been produced and deposited on photocatalytic float glass coated with TiO2 thin films by magnetron sputtering. The influence of the process parameters and of the metal amount on the final properties of the particles (quantity, size, size distribution, oxidation state etc.,) was widely investigated. Moreover, the effect of the NPs on the photocatalytic activity of the resulting materials was evaluated for the case of the decomposition of stearic acid (SA) during UV-A irradiation. The reduction of the water contact angle (WCA) during the irradiation period was measured in order to test the photo-induced super-hydrophilicity (PSH). PMID:26716202

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  9. Hydrophilicity and formation mechanism of large-pore mesoporous TiO2 thin films with tunable pore diameters

    International Nuclear Information System (INIS)

    Using n-butanol released in situ as the cosurfactant, transparent large-pore mesoporous nanocrystalline anatase (meso-nc-TiO2) thin films with narrow pore size distribution have been successfully synthesized in a Ti(OBun)4-P123-EtOH-HCl system. Furthermore, the mesopore size can be easily controlled in the range of 8.3-14.0 nm through adjusting the quantities of Ti(OBun)4, corresponding to the amount of n-butanol released in situ. X-ray diffraction, atomic force microscopy, scanning electron microscopy, transmission electron microscopy, and nitrogen sorption were used to investigate the relationship between the amount of Ti(OBun)4 and the structural parameters of the obtained meso-nc-TiO2 thin films. A reasonable mechanism is also proposed here to explain the formation of large-pore mesoporous TiO2 with tunable pore diameters. The hydrophilicity of our obtained films was evaluated by water contact angle measurement in air. It was found that, in the absence of ultraviolet (UV) illumination, the presented transparent large-pore meso-nc-TiO2 thin films exhibit high hydrophilicity

  10. Control of the optical and crystalline properties of TiO2 in visible-light active TiO2/TiN bi-layer thin-film stacks

    International Nuclear Information System (INIS)

    Multi-layered thin films of TiO2 and TiN were created by rf reactive magnetron sputtering, and their crystalline, optical, and photoelectrochemical properties were measured. The overall composition of the films (TiO2-to-TiN ratio) was kept constant with the height of each film. The number of layers and thickness of each layer was controlled to create bi-layer thin films that were composed of: 9 bi-layers, 18 bi-layers, 27 bi-layers, 36 bi-layers, and 45 bi-layers. XRD patterns were observed for each film after annealing to measure the grain size and composition of anatase and rutile as a function of temperature. It was found that the phase-transition temperature is able to be substantially controlled (between 550 deg. C and 850 deg. C) for the anatase to rutile transition by varying the number of layers/thickness of each layer. In addition, bi-layer stacking significantly affected the film's optical properties by lowering the bandgap into the visible-light region, and also showed up to three times the improvement in photoelectrochemical performance under uv and visible irradiation. Overall, bi-layer stacking of TiO2/TiN films has shown a unique and highly desirable control over several important physical characteristics that can be beneficial for many applications, such as high-temperature sensors and optoelectronic devices.

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

    Science.gov (United States)

    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.

  12. Photoactivity and hydrophilic property of SiO2 and SnO2 co-doped TiO2 nano-composite thin films

    Directory of Open Access Journals (Sweden)

    Lek Sikong

    2010-08-01

    Full Text Available SiO2 and SnO2 co-doped TiO2 nano-composite thin films were prepared by sol-gel method. The effects of film thicknessand amount of SiO2 and SnO2 co-doping into TiO2 nano-composite films on phase presence, crystallite size, photocatalyticreaction and hydrophilicity were investigated. Thickness of 3-coating layers (238 nm seems to provide the highest photocatalyticactivity. The crystallinity of anatase phases, crystallite sizes and photocatalytic reactions of SiO2 and SnO2 co-dopedTiO2 films decrease with an increase in SiO2 content. It was found that more amount of SiO2 addition seems to inhibit graingrowth and the formation of anatase phase; especially when it was synthesized at temperature less than 600C. The photocatalyticreaction seems to decrease with an increase in SiO2 doping when the concentrations of SnO2 in the composite films are fixed. It was apparent that 1SiO2/1SnO2/TiO2 composite film exhibits the highest photoactivity. Suitable amounts of SiO2and SnO2 doping into the TiO2 composite films tend to enhance the hydrophilic property of the films. It was also apparentthat the 3SiO2/3SnO2/TiO2, 5SiO2/5SnO2/TiO2 and 10SiO2/3SnO2/TiO2 composite films exhibit super hydrophilic characteristicsunder UV irradiation for 30 min.

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

    Indian Academy of Sciences (India)

    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.

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

    International Nuclear Information System (INIS)

    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.

  15. Structural and electrical studies on sol-gel derived spun TiO2 thin films

    International Nuclear Information System (INIS)

    Titanium dioxide thin films were prepared by spin coating of sol precursor onto microscopic glass slides, silicon and indium tin oxide (ITO) coated glass substrates. Spin speed was varied between 1000 and 6000 rpm. From the morphological analysis, it is found that thin films spun with speed ??4000 rpm assume higher ordered structure than those spun at a speed higher than 4000 rpm. Conduction at low voltages is believed to be variable range hopping at temperatures Ta = 0.46 eV below the conduction band edge becomes dominant at temperatures higher than 220 K. At high field charge transport is due to trap-controlled space charge limited mechanism. Traps with a density Nt?1x1022 m-3 are thought to be situated at energy level Et 0.3 eV below the conduction band and are associated with film nonstoichiometry and interface states

  16. Preillumination of TiO2 and Ta2O5 photoactive thin films as a tool to tailor the synthesis of composite materials.

    Science.gov (United States)

    Sánchez-Valencia, Juan R; Borrás, Ana; Barranco, Angel; Rico, Victor J; Espinós, Juan P; González-Elipe, Agustín R

    2008-09-01

    Illumination of TiO 2 thin films with UV light is known to induce the transformation of the surface of this material from partially hydrophobic into fully hydrophilic. The present work shows that this transformation is accompanied by other effects that may be used to control the synthesis of composite materials. For this purpose, TiO 2 and Ta 2O 5 transparent thin films with a columnar structure and open pores were prepared by electron evaporation at glancing angles. Transparent TiO 2 thin films with micropores (i.e., pores smaller than 2 nm) prepared by plasma enhanced chemical vapor deposition (PECVD) were also used. All these films became hydrophilic upon UV illumination. Rhodamine 6G and Rhodamine 800 dyes were irreversibly adsorbed within the columns of the TiO 2 and Ta 2O 5 thin films by immersion into a water solution of these molecules. Isolated and aggregated molecules of these two dyes were detected by visible absorption spectroscopy. The infiltration adsorption efficiency was directly correlated with the acidity of the medium, increasing at basic pHs as expected from simple considerations based on the concepts of the point of zero charge (PZC) in colloidal oxides. The infiltration experiments were repeated with columnar TiO 2 and Ta 2O 5 thin films that were subjected to preillumination with UV light. It was found that this treatment produced a modification in the type (isolated or aggregated) and amount of dye molecules incorporated into the pores. Moreover, the selective adsorption of a given dye in preilluminated areas of the films permitted the lithographic coloring of the films. Preillumination also controls the UV induced deposition of silver on the surface of the microporous TiO 2 thin films. It was found that the size distribution of the formed silver nanoparticles was dependent on the preillumination treatment and that a well-resolved surface plasmon resonance at around 500 nm was only monitored in the preilluminated films. A model is proposed to account for the effects induced by UV preillumination on the TiO 2 and Ta 2O 5 oxide surfaces. The possibilities of this type of light treatment for the tailored synthesis of nanocomposite thin films (i.e., dye-oxide, metal nanoparticles-oxide) are highlighted. PMID:18642860

  17. Sol-gel synthesis, characterization and optical properties of mercury-doped TiO2 thin films deposited on ITO glass substrates

    International Nuclear Information System (INIS)

    The Hg-doped and undoped nano-crystalline TiO2 films on ITO glass substrates surface and polycrystalline powders were prepared by sol-gel dip coating technique. The crystal structure and surface morphology of TiO2 were characterized by means of X-ray diffractometer (XRD), atomic force microscope (AFM), spectrophotometer, Fourier-transform infrared (FTIR), and spectroscopic ellipsometry (SE). The results indicated that the powder of TiO2, doped with 5% Hg in room temperature was only composed of the anatase phase whereas in the undoped powder exhibits an amorphous phase were present. After heat treatments of thin films, titanium oxide starts to crystallize at the annealing temperature 400 oC. The average crystallite size of the undoped TiO2 films was about 8.17 nm and was increased with Hg-doping in the TiO2 films. Moreover, the grains distributed more uniform and the surface roughness was greater in the Hg-doped TiO2 films than in the undoped one. Refractive index and porosity were calculated from the measured transmittance spectrum. The values of the index of refraction are in the range (1.95-2.49) and the porosity is in the range (47-2.8). The coefficient of transmission varies from 60 to 90%. SE study was used to determine the annealing temperature effect on the optical properties in the wavelength range from 0.25 to 2 ?m and the optical gap of the Hg-doped TiO2 thin films.

  18. TiO2:polymer bulk-heterojunction thin films made from a miscible new carbazole based TiO2 precursor with poly(N-vinylcarbazole) for enhanced charge transfer properties

    International Nuclear Information System (INIS)

    TiO2:polymer bulk-heterojunctions (BHJ) have been elaborated from hydrolysis-condensation reactions of a TiO2 precursor in contact to the surrounding air humidity in a polymer thin film. A new precursor: tetrakis(9H-carbazole-9-yl-ethyl-oxy) titanium [Ti(OeCarb)4], has been synthesized as a TiO2 precursor to form a blend with Poly(N-vinylcarbazole) (PVK) which is the archetype of non-conjugated photoconducting polymer with strong electron-donor properties. This new precursor is expected to enhance the materials miscibility because of the chemical structure of the ligand close to the PVK repetitive unit and to inhibit premature hydrolysis by a strong steric hindrance. Commercial titanium isopropoxide [Ti(iOPr)4] was used as a reference to study the influence of the chemical structure of the precursor on BHJ properties. Photoluminescence studies have shown charge transfer enhancement when Ti(OeCarb)4 is used. In order to understand this ligand effect, photoluminescence (PL) responses were correlated with surface chemical composition (XPS) and topography (AFM) of thin films. Results have shown that Ti(OeCarb)4 allows a better miscibility between TiO2 and PVK. The lower reactivity of Ti(OeCarb)4 to hydrolysis and its chemical structure close to the repetitive unit structure of the polymer are believed to play a main role in the BHJ property improvement

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

    Science.gov (United States)

    Brevet, A.; Peterl, 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.

  20. Influences of the iron ion (Fe3+)-doping on structural and optical properties of nanocrystalline TiO2 thin films prepared by sol-gel spin coating

    International Nuclear Information System (INIS)

    Titanium dioxide (TiO2) thin films doping of various iron ion (Fe3+) concentrations were deposited on silicon (Si) (100) and quartz substrates by sol-gel Spin Coating technique followed by a thermal treatment at 600 deg. C. The structure, surface morphology and optical properties, as a function of the doping, have been studied by X-ray diffractometer (XRD), Raman, ultraviolet-visible (UV-vis) and Spectroscopic Ellipsometry (SE). XRD and Raman analyzes of our thin films show that the crystalline phase of TiO2 thin films comprised only the anatase TiO2, but the crystallinity decreased when the Fe3+ content increased from 0% to 20%. During the Fe3+ addition to 20%, the phase of TiO2 thin film still maintained the amorphous state. The grain size calculated from XRD patterns varies from 29.3 to 22.6 nm. The complex index and the optical band gap (Eg) of the films were determined by the spectroscopic ellipsometry analysis. We have found that the optical band gap decreased with an increasing Fe3+ content.

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

    International Nuclear Information System (INIS)

    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)

  2. Study of the photocatalytic activity of nanocrystalline S, N-codoped TiO2 thin films and powders under visible and sun light irradiation

    International Nuclear Information System (INIS)

    Homogeneous and transparent sulfur and nitrogen (S, N)-codoped TiO2 nanocrystalline thin films were deposited on glass substrates by sol gel dip coating method using thiourea (Tu) as a source of sulfur and nitrogen. The surface structure of the films was modified by addition of different concentrations of polyethylene glycol (PEG) into the TiO2 sol. The equal powders of pure and modified TiO2 were also prepared to compare of their photocatalytic activity with films. The films and powders were characterized by different techniques like diffuse reflectance UV-Vis spectroscopy (DRS), X-ray diffraction (XRD) and scanning electron microscopy equipped with energy dispersive X-ray microanalysis (SEM-EDX). DRS exhibited a shift in optical absorption wavelength to visible region and XRD analysis showed that only the anatase TiO2 formed in both of film and powder. The photocatalytic activity was evaluated by the degradation of methyl orange (MO) as a model. The modified TiO2 films and powders showed excellent visible-light photocatalytic ability for the degradation of MO under both irradiation of visible and sun light. So that, up to 96% MO can be decomposed in sun light only within 3 h in the presence of a modified TiO2 film consist of Tu/TiO2 molar ratio of 0.45 and 0.9 g PEG. On the other hand, MO solution was discolored completely under sun light in 75 min in the presence of the modified TiO2 powder.

  3. Study of the photocatalytic activity of nanocrystalline S, N-codoped TiO2 thin films and powders under visible and sun light irradiation

    Science.gov (United States)

    Behpour, Mohsen; Atouf, Vajiheh

    2012-06-01

    Homogeneous and transparent sulfur and nitrogen (S, N)-codoped TiO2 nanocrystalline thin films were deposited on glass substrates by sol gel dip coating method using thiourea (Tu) as a source of sulfur and nitrogen. The surface structure of the films was modified by addition of different concentrations of polyethylene glycol (PEG) into the TiO2 sol. The equal powders of pure and modified TiO2 were also prepared to compare of their photocatalytic activity with films. The films and powders were characterized by different techniques like diffuse reflectance UV-Vis spectroscopy (DRS), X-ray diffraction (XRD) and scanning electron microscopy equipped with energy dispersive X-ray microanalysis (SEM-EDX). DRS exhibited a shift in optical absorption wavelength to visible region and XRD analysis showed that only the anatase TiO2 formed in both of film and powder. The photocatalytic activity was evaluated by the degradation of methyl orange (MO) as a model. The modified TiO2 films and powders showed excellent visible-light photocatalytic ability for the degradation of MO under both irradiation of visible and sun light. So that, up to 96% MO can be decomposed in sun light only within 3 h in the presence of a modified TiO2 film consist of Tu/TiO2 molar ratio of 0.45 and 0.9 g PEG. On the other hand, MO solution was discolored completely under sun light in 75 min in the presence of the modified TiO2 powder.

  4. Chemical vapor infiltration of photocatalytically active TiO2 thin films on glass microfibers

    OpenAIRE

    Sarantopoulos, Christos; Gleizes, Alain; Maury, Francis

    2007-01-01

    Due to the high diffusivity of the chemical species, chemical vapor infiltration (CVI) is a suitable process for the conformal coverage of objects with large dimensions and complex shape geometry. Its large scale capacity and high reproducibility have made the technique favorable for the deposition of non-oxide ceramics. There are few works on other materials and metal-organic compounds are rarely used as molecular precursors. In this study we focus on the deposition of anatase thin films on ...

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

    Science.gov (United States)

    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.

  6. Correlation between structure and semiconductor-to-metal transition characteristics of VO2/TiO2/sapphire thin film heterostructures

    International Nuclear Information System (INIS)

    This study focuses on the role of strain and thin film epitaxy on the semiconductor-to-metal transition (SMT) characteristics of single crystalline VO2 thin films. The VO2/TiO2 heterostructures of controlled orientations were epitaxially grown on m-cut, r-cut and c-cut sapphire substrates. Detailed structural investigations were performed using high-resolution X-ray diffraction (2?? and ? scans) and high-resolution transmission electron microscopy techniques to correlate SMT properties with microstructural characteristics. Monoclinic (M1) VO2 thin films with (1 0 0), (0 0 1) and (201) out-of-plane orientations were grown on TiO2(1 0 1)/r-sapphire, TiO2(1 0 0)/c-sapphire and TiO2(0 0 1)/m-sapphire platforms, respectively. The in-plane alignments across the interfaces were established to be [0 1 0](1 0 0)VO2||[0 1 0](1 0 1)TiO2, [1 0 0](0 0 1)VO2||[0 0 1](1 0 0)TiO2 and [010](201)VO2?[010](001)TiO2 for r-sapphire, c-sapphire and m-sapphire substrates, respectively. We were able to tune the SMT temperature of VO2 epilayers from ?313 K to 354 K (bulk Tc ? 340 K). The SMT characteristics were interpreted based upon the residual strain in the VO2 lattice, particularly along the c-axis of tetragonal VO2. This research introduces the VO2-based single crystalline heterostructures as a potential candidate for a wide range of applications where different transition temperatures are required

  7. The photocatalytic application and regeneration of anatase thin films with embedded commercial TiO2 particles deposited on glass microrods

    International Nuclear Information System (INIS)

    Anatase thin films (2 were prepared by sol-gel method. TiO2-anatase thin films were deposited on a fiberglass substrate and then ground to obtain glass microrods containing the composite films. The film structure was characterized using Raman spectroscopy, atomic absorption and UV-vis spectrophotometry, and atomic force microscopy. The photocatalytic activity of the composite films, calcined at 450 deg. C, and the regeneration of the activity under the same experimental conditions, were assessed using gas chromatography to study the photodegradation of phenol, an industrial pollutant, in water under 365 nm irradiation. The film with 15.0 wt.% of P25 TiO2 was found to be more photoactive (54 ppm of degraded phenol at 6 h of illumination) than the other ones

  8. Thermo-Optical Properties of Thin-Film TiO2–Al2O3 Bilayers Fabricated by Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Rizwan Ali

    2015-05-01

    Full Text Available We investigate the optical and thermo-optical properties of amorphous TiO\\(_2\\–Al\\(_2\\O\\(_3\\ thin-film bilayers fabricated by atomic layer deposition (ALD. Seven samples of TiO\\(_2\\–Al\\(_2\\O\\(_3\\ bilayers are fabricated by growing Al\\(_2\\O\\(_3\\ films of different thicknesses on the surface of TiO\\(_2\\ films of constant thickness (100 nm. Temperature-induced changes in the optical refractive indices of these thin-film bilayers are measured by a variable angle spectroscopic ellipsometer VASE\\textsuperscript{\\textregistered}. The optical data and the thermo-optic coefficients of the films are retrieved and calculated by applying the Cauchy model and the linear fitting regression algorithm, in order to evaluate the surface porosity model of TiO\\(_2\\ films. The effects of TiO\\(_2\\ surface defects on the films' thermo-optic properties are reduced and modified by depositing ultra-thin ALD-Al\\(_2\\O\\(_3\\ diffusion barrier layers. Increasing the ALD-Al\\(_2\\O\\(_3\\ thickness from 20 nm to 30 nm results in a sign change of the thermo-optic coefficient of the ALD-TiO\\(_2\\. The thermo-optic coefficients of the 100 nm-thick ALD-TiO\\(_2\\ film and 30 nm-thick ALD-Al\\(_2\\O\\(_3\\ film in a bilayer are (0.048 \\(\\pm\\ 0.134 \\(\\times 10 ^{-4} {^\\circ}\\mathrm {C}^{-1}\\ and (0.680 \\(\\pm\\ 0.313 \\(\\times 10^{-4} {^\\circ} \\mathrm {C}^{-1}\\, respectively, at a temperature \\(T = 62 ^\\circ \\mathrm{C}\\.

  9. Contribution of thickness dependent void fraction and TiSixOy interlayer to the optical properties of amorphous TiO2 thin films

    International Nuclear Information System (INIS)

    The optical properties of TiO2 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 TiO2 are essentially constant and approach to those of bulk TiO2 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 TiO2 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

  10. Studies of LPCVD and anodised TiO2 thin films and their photoelectrocatalytic photochemical properties for destruction of organic effluents

    International Nuclear Information System (INIS)

    TiO2 thin films prepared by CVD and anodisation methods and their applications for the photoelectrocatalytic and photocatalytic destruction of organic effluents are described in this thesis. The theoretical background of CVD, photoelectrocatalysis (PEC) and photocatalysis (PC) is introduced in Chapter 1. This chapter also contains an intensive literature review about TiO2 thin film preparation, mainly by CVD, and about PEC and PC destruction of organic effluents by TiO2 thin films. The experimental methods, which include CVD reactors, PEC cells and film characterisation and chemical analysis, are described in Chapter 2. The results for TiO2 films deposited by LPCVD on SnO2 coated glass using either TTIP or TTB precursors in the presence of O2, with or without water as a reagent, are discussed in Chapter 3 for a small CVD reactor and Chapter 4 for a large reactor. The effects of precursor, water and annealing on the crystal structure of the films have been investigated and compared. It was found that phase transition temperatures for changes from amorphous to anatase and anatase to rutile with TTIP were higher than those obtained with TTB. Water also had an effect by decreasing the temperature for depositing crystalline films. The other kind of TiO2 films prepared by anodisation of titanium mesh was studied and the results are presented in Chapter 5. PEC or PC destruction of MPA, RDX and 4-CP have been studied using TiO2 thin film anodes in small and large PEC reactors which are described in Chapter 6 and Chapter 7, respectively. PC destruction rates of organics are found to be improved significantly with an applied potential; i.e. by a PEC process. The effects of film properties, such as film crystallinity, thickness and film type on the PEC and PC efficiencies have been investigated. It was found that the different behaviour of films in PEC processes probably was due to surface effects rather than internal electric field differences. The extent of PEC and PC destruction of organics for CVD films was higher than for anodised films. The thesis concludes with an overall summary of the results and some suggestions for future work (Chapter 8). (author)

  11. Reliability of ultra-thin titanium dioxide (TiO2) films on strained-Si

    International Nuclear Information System (INIS)

    Ultra-thin high-k titanium oxide (equivalent oxide thickness ∼ 2.2 nm) films have been deposited on strained-Si/relaxed-Si0.8Ge0.2 heterolayers using titanium tetrakis iso-propoxides (TTIP) as an organometallic source at low temperature (2 gate dielectric during constant current (CCS) and voltage stressing (CVS) has been investigated. Normalized trapping centroid and trapped charge density variation with injected fluences have been investigated and also empirically modeled. Oxide lifetime is predicted using empirical reliability model developed. Dielectric breakdown and reliability of the dielectric films have been studied using constant voltage stressing. A high time-dependent dielectric breakdown (TDDB, tbd > 1000 s) is observed under high constant voltage stress

  12. Thin Film Nanocrystalline TiO2 Electrodes: Dependence of Flat Band Potential on pH and Anion Adsorption.

    Science.gov (United States)

    Minella, M; Maurino, V; Minero, C; Pelizzetti, E

    2015-05-01

    Thin nanocrystalline TiO2 films were produced on ITO conductive glass by dip-coating of a sol-gel TiO2 precursor. The transparent films were characterized from the optical and structural point of view with UV-Vis, Spectroscopic Ellipsometry, Raman and X-ray photoelectron spectroscopies, the roughness of the coating by AFM. The changes in the electrochemical properties features of ITO/TiO2 electrodes were evaluated in the presence of different electrolytes (KCI, Na2SO4 and phosphate buffer) with the aim to clarify the role of the ion adsorption on the structure of the electrical double layer. Electrochemical tests (Cyclic Voltammetry, CV, and Impedance Electrochemical Spectroscopy, EIS) showed a strong influence of the electrolyte properties on the semiconductor band edge position in the electrochemical scale and on band bending. The CV profiles recorded can be explained by considering that the interface capacity is due to the charging of surface states (e.g., Ti(IV) surface sites coordinated by oxygen atoms, ≡Ti-OH or Ti-O-Ti). The surface charge is strongly affected also by the density and nature of adsorbed ions and by dissociation of surficial OH. Of interest the fact that for the produced nanocrystalline electrodes the flat band potential, measured from the Mott-Schottky analysis of the space charge layer capacity obtained with EIS, showed a non Nernstian behavior with the pH probably caused by a change in the surface acidity as a consequence of specific anion adsorption. The modulation of flat band potential with adsorbed ions is of interest for many applications, in particular for photocatalysis (change in the redox potential of photogenerated carriers) and for photovoltaic applications like DSSC (change in the photopotentials). PMID:26504951

  13. Properties of TiO2-based transparent conducting oxide thin films on GaN(0001) surfaces

    Science.gov (United States)

    Kasai, J.; Hitosugi, T.; Moriyama, M.; Goshonoo, K.; Hoang, N. L. H.; Nakao, S.; Yamada, N.; Hasegawa, T.

    2010-03-01

    Anatase Nb-doped TiO2 transparent conducting oxide has been formed on GaN(0001) surfaces using a sputtering method. Amorphous films deposited at room temperature were annealed at a substrate temperature of 500 °C in vacuum to form single-phase anatase films. Films with a thickness of 170 nm exhibited a resistivity of 8×10-4 Ω cm with absorptance less than 5% at a wavelength of 460 nm. Furthermore, the refractive index of the Nb-doped TiO2 was well matched to that of GaN. These findings indicate that Nb-doped TiO2 is a promising material for use as transparent electrodes in GaN-based light emitting diodes (LEDs), particularly since reflection at the electrode/GaN boundary can be suppressed, enhancing the external quantum efficiency of blue LEDs.

  14. Investigation of structural, optical and photocatalytic properties of mesoporous TiO 2 thin film synthesized by sol-gel templating technique

    Science.gov (United States)

    Janitabar-Darzi, S.; Mahjoub, A. R.; Nilchi, A.

    2009-12-01

    TiO 2 surfactant-templated nanostructured thin film was fabricated by supramolecular templating technique using TiCl 4 and P-123 as raw material and surfactant, respectively. The film was produced by Sol-gel dip coating procedure due to its simple technique as well as relatively low cost. Characterization of the product was carried out by means of Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) specific surface areas, thermogravimetry-differential scanning calorimetry (TG-DSC) and UV-vis absorption spectroscopy. The as-prepared TiO 2 film showed a quasi hexagonal mesostructure, and a further increase in the meso-scale order was observed after calcination. The prepared TiO 2 film had a high surface area of 124 m 2 g -1. The film was 2-μm thick and had a closely packed of anatase particles. The direct and indirect band gap of the film was estimated from UV-vis spectroscopy data to be 4.16 and 3.69 ev, respectively. The photocatalytic activity of the prepared TiO 2 film was evaluated by Congo Red degradation. The film had excellent photocatalytic efficiencies and more than 80% Congo Red was decolorized in 60 min.

  15. Effect of annealing treatment on the photocatalytic activity of TiO2 thin films deposited by dc reactive magnetron sputtering

    Science.gov (United States)

    Arias, L. M. Franco; Arias Duran, A.; Cardona, D.; Camps, E.; Gmez, M. E.; Zambrano, G.

    2015-07-01

    Titanium dioxide (TiO2) thin films have been deposited by DC reactive magnetron sputtering on silicon and quartz substrates with different Ar/O2 ratios in the gas mixture. Substrate temperature was kept constant at 400 C during the deposition process, and the TiO2 thin films were later annealed at 700 C for 3 h. The effect of the Ar/O2 ratio in the gas flow and the annealing treatment on the phase composition, deposition rate, crystallinity, surface morphology and the resulting photocatalytic properties were investigated. For photocatalytic measurements, the variation of the concentration of the methylene blue (MB) dye under UV irradiation was followed by a change in the intensity of the characteristic MB band in the UV- Vis transmittance spectra. We report here that the as-grown TiO2 films showed only the anatase phase, whereas after annealing, the samples exhibited both the anatase and rutile phases in proportions that varied with the Ar/O2 ratio in the mixture of gases used during growth. In particular, the annealed TiO2 thin film deposited at a 50/50 ratio of Ar/O2, composed of both anatase (80%) and rutile phases (20%), exhibited the highest photocatalytic activity (30% of MB degradation) compared with the samples without annealing and composed of only the anatase phase.

  16. Sol-gel preparation of TiO2-ZrO2 thin films supported on glass rings: Influence of phase composition on photocatalytic activity

    International Nuclear Information System (INIS)

    In order to optimize the characteristics of TiO2-ZrO2 thin films supported on glass for the photocatalytic removal of VOCs, acidic sols of different composition (ZrO2, TiO2 and Ti-Zr mixed oxides) have been prepared using metal alkoxides as starting materials. The photoactive oxides were deposited on 'Raschig rings' of borosilicate glass using a dip-coating technique. The phase composition of the thin films was controlled during the sol preparation stage to produce either (1) Ti0.9Zr0.1O2 solid solutions, or (2) ZrO2/TiO2 binary metal oxides (10% and 20% molar content of Zr). The particle size of the different sols was measured by photon correlation spectroscopy, and the xerogels were characterized by XRD, N2 adsorption isotherms, and TG-DTA, so as to monitor the modifications induced by the thermal treatments. Raman spectroscopy was used to determine the crystalline structure of the supported TiO2-ZrO2 oxides, which in all cases corresponded to the anatase phase. The band gap of the thin films was estimated from the UV-vis spectra, and none of them differed significantly from that of unmodified TiO2. The photoactivity of the coated glass 'Raschig rings' was measured for the oxidation of acetone and methylcyclohexane vapors using, respectively, total recycle and single pass plug flow photoreactors. The results obtained indicate that, for the same Zr content, the photoactivity of the films containing binary metal oxides is slightly higher than that of the solid solution. In contrast, specific surface area seems to have little influence on the performance of the thin films

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

    Science.gov (United States)

    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

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

    International Nuclear Information System (INIS)

    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)

  19. Quantum-dot light-emitting diodes utilizing CdSe/ZnS nanocrystals embedded in TiO2 thin film

    International Nuclear Information System (INIS)

    Quantum-dot (QD) light-emitting diodes (LEDs) are demonstrated on Si wafers by embedding core-shell CdSe/ZnS nanocrystals in TiO2 thin films via plasma-enhanced metallorganic chemical vapor deposition. The n-TiO2/QDs/p-Si LED devices show typical p-n diode current-voltage and efficient electroluminescence characteristics, which are critically affected by the removal of QD surface ligands. The TiO2/QDs/Si system we presented can offer promising Si-based optoelectronic and electronic device applications utilizing numerous nanocrystals synthesized by colloidal solution chemistry

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

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

  3. Light-emitting diode applications of colloidal CdSe/ZnS quantum dots embedded in TiO2-δ thin film

    International Nuclear Information System (INIS)

    We report the light-emitting diode (LED) characteristics of colloidal core-shell CdSe/ZnS nanocrystal quantum dots (QDs) embedded in TiO2-δ thin films on Si substrate. High-quality CdSe/ZnS QDs were synthesized via a pyrolysis in the range of 220-280 C. The QDs were embedded in TiO2-δ thin film at 200 C by plasma-enhanced metallorganic chemical vapor deposition. The diode structure of n-TiO2-δ/QDs/p-Si showed electroluminescence characteristics, indicating the possibility of LED applications of colloidal CdSe/ZnS nanocrystal QDs embedded in oxide films on large-area Si wafer. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Optimizing preparation of the TiO2 thin film reactor using the Taguchi method

    International Nuclear Information System (INIS)

    In this study, titanium dioxide thin film was prepared using the modified chemical vapor deposition. The parameters employed to control the preparation of the catalyst include the temperature of water bath, the Ti(OC3H7)4/H2O ratio, the flow rate of carrier gas, the oxidation temperature, the oxidation time, the calcination temperature, the rotating speed of furnace, and the speed of geared motor. The orthogonal arrays in the design of experimental method proposed by Taguchi were adopted to conduct the multiple-factor experiment. The conversion rate of salicylic acid in the aqueous or heterogeneous phase photocatalysis experiment was employed to identify the optimal conditions for assembly. The results indicated that a higher conversion ratio of the organic substance could be achieved under catalytic oxidation temperature of 400 oC, calcination temperature of 550 oC, and spraying speed of 30 rpm and the optimal experimental conditions obtained in this study were irradiation with intensity of 2.9 mW cm-2 on salicylic acid at concentration of 250 mg L-1 by both agitation and aeration processes (dissolved oxygen level = 8.2 mg O2 L-1) at pH 5, which could achieve optimal hydroxyl radical yield of 5.1 x 10-17 M.

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

    International Nuclear Information System (INIS)

    Graphical abstract: Display Omitted Highlights: ► Material self-assembly in phase-separated oxides is exploited. ► Three-dimensionally nanostructured epitaxial films are grown using sputtering. ► Films are composed of well-ordered oriented nanopillars of n-type TiO2 and p-type Cu2O. ► Observed interfaces at adjacent TiO2–Cu2O columns are nearly atomically distinct. ► Absorption profile of the composite film captures a wide range of the solar spectrum. -- Abstract: Significant efforts are being devoted to the development of multifunctional thin-film heterostructures and nanostructured material architectures for components with novel applications of superconductivity, multiferroicity, solar photocatalysis and energy conversion. In particular, nanostructured assemblies with well-defined geometrical shapes have emerged as possible high efficiency and economically viable alternatives to planar photovoltaic thin-film architectures. By exploiting phase-separated self-assembly, here we present advances in a vertically oriented two-component system that offers potential for future development of nanostructured thin film solar cells. Through a single-step deposition by magnetron sputtering, we demonstrate growth of an epitaxial, composite film matrix formed as self-assembled, well ordered, phase segregated, and oriented nanopillars of n-type TiO2 and p-type Cu2O. 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 TiO2–Cu2O interfaces (i.e., needed for possible active p–n junctions), and an absorption profile that captures a wide range of the solar spectrum extending from ultraviolet to visible wavelengths. This high-quality materials system could lead to photovoltaic devices that can be optimized for both incident light absorption and carrier collection.

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

    Science.gov (United States)

    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.

  7. Effects of dip-coating speed and annealing temperature on structural, morphological and optical properties of sol-gel nano-structured TiO2 thin films

    Science.gov (United States)

    Touam, Tahar; Atoui, Mohamed; Hadjoub, Ilhem; Chelouche, Azeddine; Boudine, Boubekeur; Fischer, Alexis; Boudrioua, Azzedine; Doghmane, Abdellaziz

    2014-09-01

    We reported material characterization of the nano-structured TiO2 thin films prepared by the sol-gel dip-coating process on glass substrates. The dependence of the structural, morphological and optical properties of the synthesized films on the fabrication parameters such as withdrawal velocity and annealing temperature were investigated by the techniques of X-ray diffraction (XRD), Raman spectroscopy (RS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and UV-visible spectrophotometry. The results indicate that for the TiO2 films annealed at 500 °C there exhibits (1 0 1) XRD peak corresponding to the anatase phase of TiO2. The latter is consistent with the recorded Raman signal observed at 142 cm-1 (Eg mode) and 391 cm-1 (B1g mode), respectively. From the analyses made on the SEM micrographs and AFM images, it was revealed that the morphology and surface roughness of the thin films would depend on the withdrawal speed and the heat treatment temperature. The UV-visible spectroscopy analyses show that all the films were transparent in the visible region with an average transmittance of more than 70%. With an increase on the dip-coating speed from 1 cm/min to 3 cm/min, we observed a spectral red shift of the absorption edge from 3.76 eV to 3.71 eV, indicating a decrease in the bandgap energy (Eg) of the films.

  8. Synthesis of TiO2 nanotube array thin films and determination of the optical constants using transmittance data

    Science.gov (United States)

    Ahmadi, K.; Abdolahzadeh Ziabari, Ali; Mirabbaszadeh, K.; Ahmadi, S.

    2015-01-01

    TiO2 nanotube arrays were grown on glass substrate by ZnO nanorod sol-gel template process. XRD analysis and FESEM microscopy were employed to characterize the structural and morphological properties of the prepared nanotube. EDX and UV-Vis spectroscopy were used to assess the chemical composition and study the optical properties of the film. An optical model has been performed to simulate the optical constants and thicknesses of the films from transmittance data using the Levenberg-Marquardt algorithm via Drude model. The simulated transmittance is in good agreement with the measured spectrum in the whole measurement wavelength range. The refractive index and extinction coefficient, thickness and dielectric function of TiO2 nanotube films were calculated by Drude model. Also, the related absorption coefficient, optical bandgap and porosity were determined.

  9. KARAKTERISTIK FILM TIPIS TiO2 DOPING NIOBIUM

    Directory of Open Access Journals (Sweden)

    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%.

  10. Excellent resistive switching property and physical mechanism of amorphous TiO2 thin films fabricated by a low-temperature photochemical solution deposition method

    Science.gov (United States)

    Zou, Lilan; Hu, Wei; Xie, Wei; Chen, Ruqi; Qin, Ni; Li, Baojun; Bao, Dinghua

    2014-08-01

    High-performance resistive switching Pt/TiO2/Pt memory cells were fabricated. The amorphous TiO2 active layer was prepared by using a low-temperature photochemical solution deposition method-a simple preparation process combining first chemical solution deposition of the TiO2 film layer and subsequent ultraviolet (UV) irradiation treatment. The obtained Pt/TiO2/Pt memory cells exhibited excellent resistive switching parameters, such as centralized distribution of set and reset voltages, stable current values at high and low resistance states, and long retention time. The conductive mechanisms of high resistance state and low resistance state were Schottky emission and Ohmic conduction, respectively. The X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and scanning electron microscopy characterization of the TiO2 thin films indicated that the UV irradiation treatment can lead to decomposition of the residual organics and the formation of enhanced metal-oxide bonds in the thin films. On the basis of the analysis of current-voltage characteristics and the temperature dependence of resistance, we explained the resistive switching phenomenon for Pt/TiO2/Pt devices by using the model of formation/rupture of conductive filaments. Our study also suggested that the simple photochemical solution deposition method can be used for preparing some other oxide thin films with good resistive switching properties at low processing temperature which is promising to be extended to flexible resistive switching devices.

  11. Corrosion behavior of TiO2–NiO nanocomposite thin films on AISI 316L stainless steel prepared by sol–gel method

    International Nuclear Information System (INIS)

    TiO2–NiO nanocomposite thin films were deposited on the 316L stainless steel using sol–gel method by a dip coating technique. Different techniques such as differential thermal analysis, thermogravimetric analysis, X-ray diffraction, Fourier transform infrared spectrometry, scanning electron microscopy and scanning probe microscopy were carried out in order to characterize the structure of the coatings. The corrosion resistance of the coatings was evaluated by using Tafel polarization and electrochemical impedance spectroscopy tests of uncoated and coated specimens in a 3.5% NaCl solution at room temperature. It was found that to obtain desirable structure in coatings, the coatings should be calcined at 600 °C for one and half hour. NiTiO3, anatase and rutile were the phases obtained in different calcination conditions in air atmosphere. The results of corrosion tests indicated that with increasing the dipping times from 2 to 4, the corrosion current density first decreases but when increasing the dipping times to 6, it increases. Also the corrosion current density decreased from 186.7 nA.cm−2 (uncoated steel) to 34.21 nA.cm−2 (80%TiO2–20%NiO) and corrosion potential increased from − 150.2 mV (uncoated steel) to − 107.3 mV (67%TiO2–33%NiO). - Highlights: ► TiO2–NiO thin films were deposited on the 316L stainless steel using sol–gel method. ► Different compositions, annealing times and temperatures resulted in various phases. ► Films having different compositions showed various surface morphologies. ► Films having a composition of 80%TiO2–20%NiO showed a good corrosion protection.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  15. Preparation and optical properties of mesoporous TiO2 thin films by a two-step sol-gel technique

    International Nuclear Information System (INIS)

    This paper concerns the preparation of mesoporous titania nanopowders and thin films for use in next generation photoelectrochemical solar cells. We have recently developed a novel method for preparing mesoporous TiO2 powders using a Two-Step Sol-gel method (TSS). These materials have crystalline domains characteristic of anatase. The first step of the process involves the hydrolysis of titanium isopropoxide in a basic aqueous solution mediated by neutral surfactant. The solid product resulting from Step-1 is then treated in acidified ethanol solution containing a titanium precursor to yield anatase TiO2. The resultant powder exhibits a high surface area and large pore volume with uniform mesopores. Slurries made from the resultant powder of Steps 1 and 2 have been used to produce thin titania films on glass slides. The optical and structural properties of these films have been compared to the films made of a commercial titania (Degussa P25, BASF). We will discuss these properties with respect to the possible use of such mesoporous titania films as the wide band gap semiconductor in dye-sensitized nanocrystalline TiO2 solar cells

  16. Preparation of anatase TiO2 thin films for dye-sensitized solar cells by DC reactive magnetron sputtering technique

    International Nuclear Information System (INIS)

    Anatase titanium dioxide (TiO2) thin films are prepared by DC reactive magnetron sputtering using Ti target as the source material. In this work argon and oxygen are used as sputtering and reactive gas respectively. DC power is used at 100 W per 1 h. The distance between the target and substrate is fixed at 4 cm. The glass substrate temperature value varies from room temperature to 400 oC. The crystalline structure of the films is determined by X-ray diffraction analysis. All the films deposited at temperatures lower than 300 oC were amorphous, whereas films obtained at higher temperature grew in crystalline anatase phase. Phase transition from amorphous to anatase is observed at 400 oC annealing temperature. Transmittances of the TiO2 thin films were measured using UV-visible NIR spectrophotometer. The direct and indirect optical band gap for room temperature and substrate temperature at 400 oC is found to be 3.50, 3.41 eV and 3.50, 3.54 eV respectively. The transmittance of TiO2 thin films is noted higher than 75%. A comparison among all the films obtained at room temperature showed a transmittance value higher for films obtained at substrate temperature of 400 oC. The morphology of the films and the identification of the surface chemical stoichiometry of the deposited film at 400 oC were studied respectively, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The surface roughness and the grain size are measured using AFM.

  17. Site-specific and patterned growth of TiO2 nanotube arrays from e-beam evaporated thin titanium film on Si wafer

    International Nuclear Information System (INIS)

    Growth of TiO2 nanotubes on thin Ti film deposited on Si wafers with site-specific and patterned growth using a photolithography technique is demonstrated for the first time. Ti films were deposited via e-beam evaporation to a thickness of 350–1000 nm. The use of a fluorinated organic electrolyte at room temperature produced the growth of nanotubes with varying applied voltages of 10–60 V (DC) which remained stable after annealing at 500 °C. It was found that variation of the thickness of the deposited Ti film could be used to control the length of the nanotubes regardless of longer anodization time/voltage. Growth of the nanotubes on a SiO2 barrier layer over a Si wafer, along with site-specific and patterned growth, enables potential application of TiO2 nanotubes in NEMS/MEMS-type devices. (paper)

  18. Study on the electrical conduction mechanism of bipolar resistive switching TiO2 thin films using impedance spectroscopy

    Science.gov (United States)

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

    2010-04-01

    The electrical conduction mechanism within a resistive switching TiO2 film in its bipolar high resistance state was examined by ac impedance spectroscopy and dc current-voltage measurements. Bipolar switching, which can be initiated from a unipolar high resistance state, was attributed to both modulation of the Schottky barrier height at the film-electrode interface and the electronic energy state in the film. Numerical fittings of the impedance data revealed two distinct RC domains in series, which were attributed to an interfacial barrier (activation energy 0.1 eV) and a nonconducting layer (activation energy 0.5 eV), respectively.

  19. Incorporation of N-doped TiO2 nanorods in regenerated cellulose thin films fabricated from recycled newspaper as a green portable photocatalyst.

    Science.gov (United States)

    Mohamed, Mohamad Azuwa; Salleh, W N W; Jaafar, Juhana; Ismail, A F; Abd Mutalib, Muhazri; Jamil, Siti Munira

    2015-11-20

    In this work, an environmental friendly RC/N-TiO2 nanocomposite thin film was designed as a green portable photocatalyst by utilizing recycled newspaper as sustainable cellulose resource. Investigations on the influence of N-doped TiO2 nanorods incorporation on the structural and morphological properties of RC/N-TiO2 nanocomposite thin film are presented. The resulting nanocomposite thin film was characterized by FESEM, AFM, FTIR, UV-vis-NIR spectroscopy, and XPS analysis. The results suggested that there was a remarkable compatibility between cellulose and N-doped TiO2 nanorods anchored onto the surface of the RC/N-TiO2 nanocomposite thin film. Under UV and visible irradiation, the RC/N-TiO2 nanocomposite thin film showed remarkable photocatalytic activity for the degradation of methylene blue solution with degradation percentage of 96% and 78.8%, respectively. It is crucial to note that the resulting portable photocatalyst produced via an environmental and green technique in its fabrication process has good potential in the field of water and wastewater treatment application. PMID:26344299

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  2. Excellent resistive switching property and physical mechanism of amorphous TiO2 thin films fabricated by a low-temperature photochemical solution deposition method

    International Nuclear Information System (INIS)

    Highlights: • High-performance resistive switching Pt/TiO2/Pt memory cells were obtained. • Amorphous TiO2 layer was prepared by low-temperature photochemical deposition. • Pt/TiO2/Pt memory cells exhibited excellent resistive switching parameters. • UV irradiation led to the formation of enhanced metal-oxide bonds. • Resistive switching corresponded to the formation/rupture of conductive filaments. - Abstract: High-performance resistive switching Pt/TiO2/Pt memory cells were fabricated. The amorphous TiO2 active layer was prepared by using a low-temperature photochemical solution deposition method—a simple preparation process combining first chemical solution deposition of the TiO2 film layer and subsequent ultraviolet (UV) irradiation treatment. The obtained Pt/TiO2/Pt memory cells exhibited excellent resistive switching parameters, such as centralized distribution of set and reset voltages, stable current values at high and low resistance states, and long retention time. The conductive mechanisms of high resistance state and low resistance state were Schottky emission and Ohmic conduction, respectively. The X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and scanning electron microscopy characterization of the TiO2 thin films indicated that the UV irradiation treatment can lead to decomposition of the residual organics and the formation of enhanced metal-oxide bonds in the thin films. On the basis of the analysis of current–voltage characteristics and the temperature dependence of resistance, we explained the resistive switching phenomenon for Pt/TiO2/Pt devices by using the model of formation/rupture of conductive filaments. Our study also suggested that the simple photochemical solution deposition method can be used for preparing some other oxide thin films with good resistive switching properties at low processing temperature which is promising to be extended to flexible resistive switching devices

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

    Science.gov (United States)

    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.

  4. TiO2 and Al2O3 ultra thin nanolaminates growth by ALD; instrument automation and films characterization

    Directory of Open Access Journals (Sweden)

    H. Tiznado

    2012-01-01

    Full Text Available We report on the development of a fully operational atomic layer deposition (ALD system. This system is computer controlled and can deposit multilayered systems without user intervention. We describe the design of manifold, reaction chamber and exhaust. Additionally we give some features of the automatization software and electronics. To evaluate the ALD performance we used as precursor trymethyl aluminum (TMA and tetrakis (dimethylamino titanium (TDMAT to deposit Al2O3 and TiO2, respectively, in nanolaminated film structures. The thicknesses and composition of the films are precisely controlled, as determined by spectroscopic ellipsometry, and the nanolaminates have a sharp interface as indicated by Auger depth profile.

  5. Synthesis and characterization of C-doped TiO2 thin films for visible-light-induced photocatalytic degradation of methyl orange

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • C-TiO2 thin films were successfully synthesized by modified sol–gel method based on the self-assembly technique. • Tween 80, one kind of hydrocarbon surfactants, was used as template and carbon precursor. • A thorough material characterization was performed to determine the effect of calcination time on the structural and optical properties of the synthesized catalyst films. - Abstract: C-TiO2 thin films were synthesized by a modified sol–gel route based on the self-assembly technique exploiting Tween80 (T80) as a pore directing agent and carbon source. The effect of calcination time on the photocatalytic activity of C-doped TiO2 catalyst was studied. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transforms infrared (FTIR), UV–vis diffuse reflectance spectroscopy, and photoluminescence spectra (PL). The XRD results showed that C-TiO2 sample calcined at 400 °C for various times exhibited anatase phase and no other crystal phase was identified. C-TiO2 exhibited a shift in an absorption edge of samples in the visible region than that of conventional or reference TiO2. The XPS results showed an existence of C in the TiO2 catalysts and C might be existed as C-O-Ti group. Moreover, the C-TiO2 thin film calcined at 400 °C for 30 min showed the lowest PL intensity due to a decrease in the recombination rate of photogenerated electrons and holes under UV light irradiation. Also the photocatalytic activity of synthesized catalyst was evaluated by decomposition of methyl orange (MO) under visible light irradiation. The results showed that the optimum preparations of C-TiO2 thin films were found to be under calcination temperature of 400, calcination time of 30 min, and with preparation 9 layers film

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

    OpenAIRE

    You, Shu-Hai; Guo, Ming-Hua

    2013-01-01

    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 ...

  7. Optical Properties of Ultrathin Copper Thin Films Sandwiched between Nb-Doped TiO2 Films Studied with Spectroscopic Ellipsometry

    Science.gov (United States)

    Lee, Hosuk; Lee, Hosun; Park, Jun-Hyuk; Kim, Han-Ki; Kong, Bo Hyun; Koun Cho, Hyung

    2011-05-01

    Cu thin films sandwiched between Nb-doped TiO2 (NTO) thin films were grown on glass substrates using tilted-dual target DC magnetron sputtering deposition. The thicknesses of the top and bottom NTOs were nominally 30 nm, and the thicknesses of the Cu films (t) varied between 1.5 nm and 50 nm. We measured the ellipsometric angles (Ψ,Δ) of the NTO/Cu/NTO/glass by using spectroscopic ellipsometry and estimated the thicknesses and dielectric functions of the Cu films by using a multi-layer model analysis. Transmission electron microscopy measurements showed that the Cu layers evolved from aggregates of Cu nanoparticles to coalesced Cu thin films as the Cu film thickness increased. Sheet resistance data also showed that the t = 8 nm film was near the percolation threshold, suggesting that films thinner than 8 nm were aggregations of Cu nanoparticles that were not well-connected. The films thicker than 8 nm were above the percolation threshold. From the Drude model, we estimated the plasmon frequency (ωp) and the electron relaxation time (τ), which were found to increase with increasing film thickness. By applying standard critical point analysis to the second derivatives of the dielectric function spectra, we found several peaks near 1.5, 2.1, 2.5, 3.5, and 4.3 eV, and attributed to interband transitions. The peak energies (except 1.5 eV) matched to the band structure calculations of bulk Cu found in the literature.

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

    International Nuclear Information System (INIS)

    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

  9. On the optical, structural, and morphological properties of ZrO2 and TiO2 dip-coated thin films supported on glass substrates

    International Nuclear Information System (INIS)

    This article reports the optical and morphological properties of dip-coated TiO2 and ZrO2 thin films on soda-lime glass substrates by metal-organic decomposition (MOD) of titaniumIV and zirconiumIV acetylacetonates respectively. Thermogravimetric and differential thermal analysis (DTA-TG) were performed on the precursor powders, indicating pure TiO2 anatase and tetragonal ZrO2 phase formation. Phase crystallization processes took place in the range of 300-500 deg. C for anatase and of 410-500 deg. C for ZrO2. Fourier Transform Infrared Spectroscopy (FT-IR) was used to confirm precursor bidentate ligand formation with keno-enolic equilibrium character. Deposited films were heated at different temperatures, and their structural, optical and morphological properties were studied by grazing-incidence X-ray Diffraction (GIXRD) and X-Ray Photoelectron Spectroscopy (XPS), Ultraviolet Visible Spectroscopy (UV-Vis), and Atomic Force Microscopy (AFM) respectively. Film thinning and crystalline phase formation were enhanced with increasing temperature upon chelate decomposition. The optimum annealing temperature for both pure anatase TiO2 and tetragonal ZrO2 thin films was found to be 500 deg. C since solid volume fraction increased with temperature and film refractive index values approached those of pure anatase and tetragonal zirconia. Conditions for clean stoichiometric film formation with an average roughness value of 2 nm are discussed in terms of material binding energies indicated by XPS analyses, refractive index and solid volume fraction obtained indirectly by UV-Vis spectra, and crystalline peak identification provided by GIXRD

  10. Annealing time dependence of the physical, electrical and pH response characteristics of spin coated TiO2 thin films

    Science.gov (United States)

    Zulkefle, M. A.; Rahman, R. A.; Yusoff, K. A.; Abdullah, W. F. H.; Rusop, M.; Herman, S. H.

    2015-11-01

    Titanium dioxide (TiO2) thin film was deposited on indium tin oxide (ITO) substrate and used as sensing membrane of EGFET pH sensor. The thin film was fabricated using sol- gel spin coating method. All samples were annealed at 400 C but the annealing time was varied. This is done to study the effects of annealing time on physical and electrical properties of titanium dioxide thin film. The sensitivity of each sample towards H+ ion was measured and result shows that sample annealed for 45 minutes has the highest sensitivity (52.6 mV/pH). It is found that increasing annealing duration will increase the pH sensitivity but a limit will be reached at certain point. Longer annealing processes done beyond this point will results in lower pH sensitivity.

  11. Exploring a new phenomenon in the bactericidal response of TiO2 thin films by Fe doping: Exerting the antimicrobial activity even after stoppage of illumination

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Highly uniform Fe–TiO2 thin films were deposited on glass using sol–gel hot-dipping technique. • The photocatalytic properties were studied upon UV and visible irradiation. • By Fe doping into TiO2 structure, its microbial performance was prolonged even after stopping the illumination. • Due to Fe doping, the significant improvement in bactericidal coating was evident. - Abstract: Antibacterial properties of Fe-doped TiO2 thin films prepared on glass by the sol–gel hot-dipping technique were studied. The films were characterized by X-ray diffraction, field emission scanning electron microscopy, scanning probe microscopy and X-ray photoelectron spectroscopy. The photocatalytic activities were evaluated by measuring the decomposition rate of methylene blue under ultra violet and visible light. The antibacterial properties of the coatings were investigated against Escherichia coli, Staphylococcus aureus, Saccharomyces cerevisia and Aspergillus niger. The principle of incubation methods was also discussed. The results indicated that Fe doping of thin films eventuated in high antibacterial properties under visible light and this performance remained even after stoppage of illumination. This article tries to provide some explanation for this fact

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

    International Nuclear Information System (INIS)

    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

  13. Effect of interfacial coupling on photocatalytic performance of large scale MoS2/TiO2 hetero-thin films

    International Nuclear Information System (INIS)

    Interface electronic behavior of two-dimensional large scale MoS2/TiO2 hetero-thin films has been studied using photoemission spectroscopy. We show a clear experimental evidence for type II band alignment and upward band bending (∼0.55 eV) at the interface of this system. The valence band offset at monolayer MoS2/TiO2 interface was measured to be 2.15 eV, while the conduction band offset was 1.00 eV. The unique interface band positions introduce a strong build-in electric field for efficient electron-hole separation. In addition, thermal treatment results in better interfacial coupling and charge separation efficiency thus enhanced visible light photoactivity. Our results explicate the mechanism and emphasize its huge potential in visible light photocatalysis

  14. Schottky junction/ohmic contact behavior of a nanoporous TiO2 thin film photoanode in contact with redox electrolyte solutions

    Directory of Open Access Journals (Sweden)

    Masao Kaneko

    2011-02-01

    Full Text Available The nature and photoelectrochemical reactivity of nanoporous semiconductor electrodes have attracted a great deal of attention. Nanostructured materials have promising capabilities applicable for the construction of various photonic and electronic devices. In this paper, a mesoporous TiO2 thin film photoanode was soaked in an aqueous methanol solution using an O2-reducing Pt-based cathode in contact with atmospheric air on the back side. It was shown from distinct photocurrents in the cyclic voltammogram (CV that the nanosurface of the mesoporous n-TiO2 film forms a Schottky junction with water containing a strong electron donor such as methanol. Formation of a Schottky junction (liquid junction was also proved by MottSchottky plots at the mesoporous TiO2 thin film photoanode, and the thickness of the space charge layer was estimated to be very thin, i.e., only 3.1 nm at ?0.1 V vs Ag/AgCl. On the other hand, the presence of [Fe(CN6]4? and the absence of methanol brought about ohmic contact behavior on the TiO2 film and exhibited reversible redox waves in the dark due to the [Fe(CN6]4?/3? couple. Further studies showed that multiple Schottky junctions/ohmic contact behavior inducing simultaneously both photocurrent and overlapped reversible redox waves was found in the CV of a nanoporous TiO2 photoanode soaked in an aqueous redox electrolyte solution containing methanol and [Fe(CN6]4?. That is, the TiO2 nanosurface responds to [Fe(CN6]4? to give ohmic redox waves overlapped simultaneously with photocurrents due to the Schottky junction. Additionally, a second step photocurrent generation was observed in the presence of both MeOH and [Fe(CN6]4? around the redox potential of the iron complex. It was suggested that the iron complex forms a second Schottky junction for which the flat band potential (Efb lies near the redox potential of the iron complex.

  15. Synthesis and characterization of C-doped TiO2 thin films for visible-light-induced photocatalytic degradation of methyl orange

    Science.gov (United States)

    Hassan, Mohamed Elfatih; Cong, Longchao; Liu, Guanglong; Zhu, Duanwei; Cai, Jianbo

    2014-03-01

    C-TiO2 thin films were synthesized by a modified sol-gel route based on the self-assembly technique exploiting Tween80 (T80) as a pore directing agent and carbon source. The effect of calcination time on the photocatalytic activity of C-doped TiO2 catalyst was studied. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transforms infrared (FTIR), UV-vis diffuse reflectance spectroscopy, and photoluminescence spectra (PL). The XRD results showed that C-TiO2 sample calcined at 400 C for various times exhibited anatase phase and no other crystal phase was identified. C-TiO2 exhibited a shift in an absorption edge of samples in the visible region than that of conventional or reference TiO2. The XPS results showed an existence of C in the TiO2 catalysts and C might be existed as COTi group. Moreover, the C-TiO2 thin film calcined at 400 C for 30 min showed the lowest PL intensity due to a decrease in the recombination rate of photogenerated electrons and holes under UV light irradiation. Also the photocatalytic activity of synthesized catalyst was evaluated by decomposition of methyl orange (MO) under visible light irradiation. The results showed that the optimum preparations of C-TiO2 thin films were found to be under calcination temperature of 400, calcination time of 30 min, and with preparation 9 layers film.

  16. Microstructure and optical dispersion characterization of nanocomposite sol-gel TiO2-SiO2 thin films with different compositions

    Science.gov (United States)

    Kermadi, S.; Agoudjil, N.; Sali, S.; Zougar, L.; Boumaour, M.; Broch, L.; En Naciri, A.; Placido, F.

    2015-06-01

    Nanocomposite TiO2-SiO2 thin films with different compositions (from 0 to 100 mol% TiO2) were deposited by sol-gel dip-coating method on silicon substrate. Crystal structure, chemical bonding configuration, composition and morphology evolutions with composition were followed by Raman scattering, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy and scanning electron microscopy respectively. The refractive index and the extinction coefficient were derived in a broad band wavelength (250-900 nm) from spectroscopic ellipsometry data with high accuracy and correlated with composition and microstructure. Results showed an anatase structure for 100% TiO2 with a grain size in 6-10 nm range. Whereas, the inclusion of SiO2 enlarges the optical band gap and suppresses the grain growth up to 4 nm in size. High TiO2 dispersion in SiO2 matrix was observed for all mixed materials. The refractive index (at λ = 600 nm) increases linearly with composition from 1.48 (in 100% SiO2) to 2.22 (in 100% TiO2) leading to lower dense material, its dispersion being discussed in terms of the Wemple-DiDomenico single oscillator model. Hence, the optical parameters, such optical dispersion energies E0 and Ed, the average oscillators, strength S0 and wavelength λ0 and the ratio of the carrier concentration to the effective mass N/m∗ have been derived. The analysis revealed a strong dependence on composition and structure. The optical response was also investigated in term of complex optical conductivity (σ) and both volume and surface energy loss functions (VELF and SELF).

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

    Indian Academy of Sciences (India)

    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.

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

    Science.gov (United States)

    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.

  19. Initial growth mechanisms of ZrO2 and TiO2 thin films using cycloheptatrienyl-cyclopentadienyl heteroleptic precursors: A comparative study by density functional theory

    Science.gov (United States)

    Zhou, Guangfen; Ren, Jie; Zhang, Shaowen

    2013-10-01

    The initial growth mechanisms of atomic layer deposition (ALD) of ZrO2 and TiO2 thin films using cycloheptatrienyl (CHT)-cyclopentadienyl (Cp) precursors on Sisbnd OH surface have been investigated theoretically. The reactions of CpMeZr(CHT) and CpTi(CHT) with Sisbnd OH surface proceed through similar reaction pathways. The reaction of CpTi(CHT) requires much more energies than that of CpMeZr(CHT). Chemisorption of the CHT-Cp precursors on Sisbnd OH surface could not be found. The most stable adsorption states of both CpMeZr(CHT) and CpTi(CHT) are formed via CHT rings. The previous experiments have shown that an ALD-window has been established when depositing ZrO2 thin films, but has not been established when depositing TiO2 thin films. Our calculation results show that the adsorption of CpMeZr(CHT) is energetically favorable, but the adsorption of CpTi(CHT) is thermodynamic unfavorable. One theoretical explanation is given for this observed difference from the viewpoint of precursor adsorption.

  20. Structural evolution and hydrogen sulfide sensing properties of NiTiO3-TiO2 sol-gel thin films containing Au nanoparticles

    International Nuclear Information System (INIS)

    Thin films composed of a matrix of titanium and nickel oxides, doped with gold nanoparticles have been prepared with the sol-gel method and annealed at different time/temperature combinations. Structural characterizations demonstrate the crystallization of nickel titanate and of TiO2-rutile due to nickel capability to promote rutile crystallization over anatase. Optical characterizations show a tunable refractive index of the samples according to the Ti/Ni ratio, and a high amount of residual porosity even after high temperature annealing. Sensor functionality measurements were performed with H2, CO and H2S: high sensitivity for hydrogen sulfide detection has been proved, and the cross sensitivity to the other two gases can be tuned by controlling the nickel amount. For high Ni concentrations, the matrix is composed of NiTiO3 and TiO2-rutile, and no cross sensitivity is experienced. For lower Ni amounts, TiO2-anatase starts to crystallize and the films become sensitive to H2 and CO.

  1. Studies on the room temperature growth of nanoanatase phase TiO2 thin films by pulsed dc magnetron with oxygen as sputter gas

    International Nuclear Information System (INIS)

    The anatase phase titanium dioxide (TiO2) thin films were deposited at room temperature by pulsed dc magnetron sputtering using pure oxygen as sputter gas. The structural, optical, electrical, and electrochromic properties of the films have been studied as a function of oxygen pressure in the chamber. The x-ray diffraction results indicate that the films grown above 4.5x10-2 mbar are nanocrystalline (grain size of 28-43 nm) with anatase phase. The films deposited at the chamber pressure of 7.2x10-2 mbar are found to be highly crystalline with a direct optical band gap of 3.40 eV, refractive index of 2.54 (at λ=400 nm), and work function of 4.77 eV (determined by the Kelvin probe measurements). From the optical emission spectra of the plasma and transport of ions in matter calculations, we find that the crystallization of TiO2 at room temperature is due to the impingement of electrons and ions on the growing films. Particularly, the negative oxygen ions reflected from the target by 'negative ion effects' and the enhanced density of TiO, TiO+, TiO2+, and O2+ particles in the plasma are found to improve the crystallization even at a relatively low temperature. From an application point of view, the film grown at 7.2x10-2 mbar was studied for its electrochromic properties by protonic intercalation. It showed good electrochromic behavior with an optical modulation of ∼45%, coloration efficiency of 14.7 cm2 C-1, and switching time (tc) of 50 s for a 2x2 cm2 device at λ=633 nm

  2. Studies on the room temperature growth of nanoanatase phase TiO2 thin films by pulsed dc magnetron with oxygen as sputter gas

    Science.gov (United States)

    Karuppasamy, A.; Subrahmanyam, A.

    2007-03-01

    The anatase phase titanium dioxide (TiO2) thin films were deposited at room temperature by pulsed dc magnetron sputtering using pure oxygen as sputter gas. The structural, optical, electrical, and electrochromic properties of the films have been studied as a function of oxygen pressure in the chamber. The x-ray diffraction results indicate that the films grown above 4.510-2mbar are nanocrystalline (grain size of 28-43nm) with anatase phase. The films deposited at the chamber pressure of 7.210-2mbar are found to be highly crystalline with a direct optical band gap of 3.40eV, refractive index of 2.54 (at ? =400nm), and work function of 4.77eV (determined by the Kelvin probe measurements). From the optical emission spectra of the plasma and transport of ions in matter calculations, we find that the crystallization of TiO2 at room temperature is due to the impingement of electrons and ions on the growing films. Particularly, the negative oxygen ions reflected from the target by "negative ion effects" and the enhanced density of TiO, TiO +, TiO2+, and O2+ particles in the plasma are found to improve the crystallization even at a relatively low temperature. From an application point of view, the film grown at 7.210-2mbar was studied for its electrochromic properties by protonic intercalation. It showed good electrochromic behavior with an optical modulation of 45%, coloration efficiency of 14.7 cm2C-1, and switching time (tc) of 50s for a 22 cm2 device at ? =633nm.

  3. The cooperation effect of mixed PEGs with different molecular weights on the morphology of TiO2 porous thin films

    International Nuclear Information System (INIS)

    We synthesized TiO2 porous thin films with well-shaped pores and uniform pore size by utilizing the cooperation effect of mixed PEGs with different molecular weights. The pore sizes were about 190 nm and 220 nm for single PEG and double PEGs, respectively, while in the case of triple PEGs, the pore size ranged from about 190 nm to 500 nm. The wall thickness was affected by the difference in chain length of mixed PEGs and a thicker wall produced thermally stable pores. The optimal size distribution and shape of pores could be obtained by using two proper PEGs.

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

    Indian Academy of Sciences (India)

    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.

  5. Synthesis of uniformly dispersed anatase nanoparticles inside mesoporous silica thin films via controlled breakup and crystallization of amorphous TiO2 deposited using atomic layer deposition

    Science.gov (United States)

    Sree, Sreeprasanth Pulinthanathu; Dendooven, Jolien; Masschaele, Kasper; Hamed, Heidari M.; Deng, Shaoren; Bals, Sara; Detavernier, Christophe; Martens, Johan A.

    2013-05-01

    Amorphous titanium dioxide was introduced into the pores of mesoporous silica thin films with 75% porosity and 12 nm average pore diameter via Atomic Layer Deposition (ALD) using alternating pulses of tetrakis(dimethylamino)titanium and water. Calcination provoked fragmentation of the deposited amorphous TiO2 phase and its crystallization into anatase nanoparticles inside the nanoporous film. The narrow particle size distribution of 4 +/- 2 nm and the uniform dispersion of the particles over the mesoporous silica support were uniquely revealed using electron tomography. These anatase nanoparticle bearing films showed photocatalytic activity in methylene blue degradation. This new synthesis procedure of the anatase nanophase in mesoporous silica films using ALD is a convenient fabrication method of photocatalytic coatings amenable to application on very small as well as very large surfaces.

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

    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

  8. Electronic structure of TiO2 thin films and LaAlO3-SrTiO3 heterostructures: the role of titanium 3d1 states in magnetic and transport properties

    OpenAIRE

    Drera, Giovanni

    2012-01-01

    In this Thesis, a study of the electronic structure of two Ti-based oxide systems, TiO2 thin films and the ultra-thin LaAlO3-SrTiO3 (LAO-STO) heterojunctions, is given. A weak room-temperature ferromagnetism (FM) has been detected in slightly reduced TiO2 thin film and in other oxides; as these materials are insulating closed-shell systems, this phenomenon has been classified as "d0 magnetism". Since this magnetism could be related to the growth process and to the presence of defects (oxygen ...

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

    International Nuclear Information System (INIS)

    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

  10. Derivation and Optical Properties of Co, Mn, Nd Doped SiOand SiO2-TiO2 Thin Films

    International Nuclear Information System (INIS)

    In this research, SiO2-TiO2 and Co, Mn, Nd doped SiO2 thin films were prepared by the sol-gel-dip coating method on glass substrates using Si(OC2H5)4 (TEOS, tetraethylorthosilicate) and Ti(OBu)4 (tetrabutylorthotitanate) as starting materials. Precursor solutions were prepared by dissolving Si(OC2H5)4 and Ti(OBu)4 in ethanol. Various layers of coatings were obtained at room temperature by sol-gel dip-coating process at a withdrawal speed of 10 mm/sec. The coated substrates were exposed to heat treatment at 650 degree. The effect of chemistry of the precursor solution on the microstructure and optical properties of the films were examined by UV-VIS, AFM (Atomic Force Microscopy) and SE (Spectroscopic Ellypsometry). Band gaps of the films were determined by using absoption spectrum

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

    International Nuclear Information System (INIS)

    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

  12. Improvement in performance of Si-based thin film solar cells with a nanocrystalline SiO2TiO2 layer

    International Nuclear Information System (INIS)

    In this paper, titanium dioxide (TiO2) solution with grain sizes of 15 nm is prepared by microwave hydrothermal synthesis, and then mixed with silicon dioxide (SiO2) solution to yield different SiO2/TiO2 ratios. The mixed solution is then solgel spin-coated on glass as an anti-reflecting and self-cleaning bi-functional layer. The experimental results show that the transmittance is optimized not only by minimizing the reflectance by reflective index matching at the glass/air interface, but also by improving the film/glass interface adhesion. Adding SiO2 into TiO2 in a weight ratio of 5 leads to the highest average transmittance of 93.6% which is 3% higher than that of glass. All of the SiO2TiO2 films exhibit a remarkable inherent hydrophilicity even when not illuminated by ultra-violet light. Using the optimized SiO2TiO2 film in a hydrogenated amorphous silicon/microcrystalline silicon tandem, solar cell increases its conversion efficiency by 5.2%. Two months of outdoor testing revealed that cells with the SiO2TiO2 film avoid 1.7% of the degradation loss that is caused by dust and dirt in the environment. - Highlights: High-transmittance and self-cleaning nano-sized SiO2TiO2 films are prepared. Using SiO2TiO2 film can increase average transmittance from 90.5% (glass) to 93.6%. The SiO2TiO2 films have naturally hydrophilicity with water contact angles < 13. Cells with the film have a 4.9% higher photocurrent than cells without the film

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

    International Nuclear Information System (INIS)

    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)

  14. Preparation and Electrical Properties of TiO2/SnO2 Nanocrystalline Films

    Directory of Open Access Journals (Sweden)

    CUI Xu-Mei, ZUO Cheng-Yang, LAN De-Jun, WANG Jun

    2013-11-01

    Full Text Available The effect of SnO2 nanocrystalline coatings on the performance of dye-sensitized solar cells (DSSC based on TiO2-nanoparticle photoanode was studied. The TiO2-nanoparticle photoanode was prepared by screen-printing technique, and the SnO2 nanocrystalline films were coated on TiO2 nanoparticles by soaking TiO2 photoanodes in SnO2 solution with different concentrations or different time. SEM images indicate SnO2 nanocrystalline films have smaller surface grains than the TiO2 nanocrystalline films. The electrical properties of the films indicate that SnO2 thin films growing on the TiO2 films by soaking TiO2 films in 0.4 mol /L SnO2 solution for 50 min play a positive role on the structure and performance of the TiO2 films, and the conversion efficiency of the solar cell with TiO2/SnO2 photoanode is about 7% higher than that of TiO2 films.

  15. Li–N doped and codoped TiO2 thin films deposited by dip-coating: Characterization and photocatalytic activity under halogen lamp

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Li and N have a synergetic effect on photocatalytic efficiency of codoped TiO2 under halogen lamp. • (Li, N) dopants decrease the recombination rate of photogenerated e–h. • (Li, N) dopants induce an increase of the energy gap, Eg. • A decrease of crystallinity of the thin films seems to occur for high loadings of co-doping. - Abstract: Li-, N-doped and codoped TiO2 powders and thin films, deposited on glass substrate using dip-coating method and Ti(OBu)4 as precursor, were prepared and their structural properties were investigated using grazing angle X-ray diffraction (GXRD), Raman spectroscopy, time resolved luminescence, X-ray photoelectron spectroscopy (XPS), ground state diffuse reflectance absorption and scanning electron microscopy (SEM). Unlike the powder samples, thin films with the same composition and calcination temperature exhibited lower crystallinity degree along with the prevalence of the anatase phase. Ground state diffuse reflectance absorption studies carried on the nanopowders have shown that both the Li and N dopants led to an increase of the band gap. XPS studies revealed differences in the binding energy of N in the presence and in the absence of Li, which was explained in terms of a modification in the chemical environment of N when Li is introduced. The photocatalytic activity of the ensuing film toward the degradation of aromatic amine pollutant revealed a huge enhancement upon doping with N or codoping with N and Li. This behavior is probably provide by a charge-transfer-complex mechanism in which neither the photocatalyst nor the organic compounds absorbs visible light by itself. The improvement in the photocatalytic properties occurred simultaneously with the increase of the lifetime of the charge carriers whenever N and Li were introduced at a level 2%

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

    International Nuclear Information System (INIS)

    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.

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

    Science.gov (United States)

    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.

  18. Optical and structural properties of nanocrystalline anatase (TiO2) thin films prepared by non-aqueous sol-gel dip-coating

    International Nuclear Information System (INIS)

    Anatase (TiO2) thin films were grown by non-aqueous sol-gel dip-coating using titanium (IV) n-butoxide as precursor and 1-butanol as solvent. High withdrawal speed of 4.7 mm/s in dip-coating resulted in defect free films of 100 nm average film thickness after subsequent heat treatments. According to scanning electron microscope and X-ray diffraction measurements, the films consisted of nanocrystalline anatase with 30 nm mean crystallite size. Refractive index n(λ) and extinction coefficient k(λ) were determined over the wavelength range from 200 to 1650 nm. The optical band gap of the film material was approximately 3.2 eV. The results showed very similar optical characteristics to those that are accomplished with chemically more reactive aqueous sol-gel processes. Furthermore, it was found that in addition to porosity, coordination number of Ti atoms to nearest oxygen neighbors is likely to have a significant role in explaining differences of optical properties between bulk anatase and thin film materials of the present work.

  19. Equilibrium and Kinetic Aspects in the Sensitization of Monolayer Transparent TiO2 Thin Films with Porphyrin Dyes for DSSC Applications

    OpenAIRE

    Rita Giovannetti; Marco Zannotti; Leila Alibabaei; Stefano Ferraro

    2014-01-01

    Free base, Cu(II) and Zn(II) complexes of the 2,7,12,17-tetrapropionic acid of 3,8,13,18-tetramethyl-21H,23H porphyrin (CPI) in solution and bounded to transparent monolayer TiO2 nanoparticle films were studied to determine their adsorption on TiO2 surface, to measure the adsorption kinetics and isotherms, and to use the results obtained to optimize the preparation of DSSC photovoltaic cells. Adsorption studies were carried out on monolayer transparent TiO2 films of a known thickness. Langmui...

  20. Effects of Co doping on structure and optical properties of TiO2 thin films prepared by sol–gel method

    International Nuclear Information System (INIS)

    Co-doped TiO2 thin films were synthesized on quartz substrates by sol–gel method. Atomic force microscopy results indicate that the surfaces of the Ti1−xCoxO2 (0 ≤ x ≤ 0.10) films become smooth and compact with increasing Co content. X-ray diffraction results show that all the films are rutile phase structure and Co doping leads to lattice contraction. X-ray photoelectron spectroscopy results reveal that the predominant oxidation state of Co is divalent. Peak positions of Raman-active modes (B2g, A1g and Eg) shift to lower frequency with increasing Co content. The refractive index n at 670 nm from transmittance spectra increases with increasing Co content. The OBG varies between 3.10 and 3.26 eV. Note that optical band gap (OBG) first increases and then decreases with increasing Co content, reaching its maximum value when x is 0.03. These results suggest that the increasing mechanism of OBG is related to the decrease of grain size, compressive stress, and reduction of rutile TiO2, and the decreasing mechanism of OBG is involved with defect and impurity. The competition of the two mechanisms leads to the strange change of OBG. - Highlights: ► Ti1−xCoxO2 thin films (0 ≤ x ≤ 0.1) were fabricated by the sol–gel method. ► Increase in Co contents results in Raman shifts to lower frequencies. ► The packing density increases with increasing Co doping. ► The optical band gap increases and then decreases with the increasing Co content. ► The optical band gap varies between 3.1 and 3.26 eV.

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

    International Nuclear Information System (INIS)

    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

  2. Visible light induced cell damage of Gram positive bacteria by N-doped TiO2 mesoporous thin films

    International Nuclear Information System (INIS)

    Highly ordered N-doped titania mesoporous inorganic–organic hybrid thin films were prepared according to a refined recipe by an evaporative induced self-assembly route using Pluronic P123 as the template. Films were characterized by a grazing incident small angle X-ray scattering, atomic force microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and X-ray diffraction. Visible light induced bactericidal activity was performed on Gram-positive bacteria (Bacillus amyloliquifacience (NCIM 2829)). Bacterial cell death was confirmed by cell viability assay and inhibition of bacterial growth against reactive oxygen species induction is reported. - Highlights: ► N-doped mesoporous titania thin films were prepared by using sol–gel process. ► The titania thin films have highly ordered Im3m cubic crystalline arrangement. ► Due to N-doping the band gap of the titania thin films was reduced. ► The bactericidal activity under visible light irradiation was tested

  3. Change of resistive-switching in TiO2 films with additional HfO2 thin layer

    International Nuclear Information System (INIS)

    We have fabricated TiN/(HfO2)/TiO2/Pt/Ti stacks on SiO2/Si substrates and investigated the characteristics of the bipolar resistive switching of those stacks. Compared to the single TiO2 structure, more stable bipolar switching in the current-voltage curve was accomplished in the HfO2 /TiO2 structure. We obtained a smaller range of SET variation, a larger sensing margin, and higher resistance values of the high-resistance state with an additional HfO2 layer. Especially, in the case of the HfO2/TiO2 structure, the set voltage was decreased after O2 annealing. The heat treatment in an ambient of O2 and an additional HfO2 layer can improve the bipolar resistive switching behavior for resistive random access memory applications.

  4. Two-step nitridation of photocatalytic TiO2 films by low energy ion irradiation

    International Nuclear Information System (INIS)

    Nitridation of TiO2 films is performed by the simultaneous irradiation of low-energy N2+ and H2+ ions under substrate-heating condition. Spectroscopic observations of the resultant films clarify the formation of nitrogen-substituted TiO2 (TiO2-xNx) with large N fractions and the agglomeration of undesirable oxynitride species attributed to the deep states in the band gap. We find that the addition of a thin TiO2 cap layer on the ion-irradiated films improves the nitrogen bonding structure and distribution near the surfaces, leading to a good photocatalytic performance even in the visible region

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

    OpenAIRE

    Shah Athar Ali; Umar Akrajas Ali; Salleh Muhamad Mat

    2016-01-01

    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 ...

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

    Science.gov (United States)

    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.

  7. Spectroscopic ellipsometry characterization of amorphous and crystalline TiO2 thin films grown by atomic layer deposition at different temperatures

    Science.gov (United States)

    Saha, D.; Ajimsha, R. S.; Rajiv, K.; Mukherjee, C.; Gupta, M.; Misra, P.; Kukreja, L. M.

    2014-10-01

    TiO2 thin films of widely different structural and morphological characteristics were grown on Si (1 0 0) substrates using Atomic Layer Deposition (ALD) by varying the substrate temperature (Ts) in a wide range (50 °C ≤ Ts ≤ 400 °C). Spectroscopic ellipsometry (SE) measurements were carried out to investigate the effect of growth temperature on the optical properties of the films. Measured SE data were analyzed by considering double layer optical model for the sample together with the single oscillator Tauc-Lorentz dispersion relation. Surface roughness was taken into consideration due to the columnar growths of grains in crystalline films. The refractive index was found to be increased from amorphous (Ts ≤ 150 °C) to the nanocrystalline films (2500 film obtained at the amorphous to crystalline phase transformation temperature of 200 °C, impeded SE measurement. The dispersions of refractive indices below the interband absorption edge were found to be strongly correlated with the single oscillator Wemple-DiDomenico (WD) model. The increase in dispersion energy parameter in WD model from disordered amorphous to the more ordered nanocrystalline films was found to be associated with the increase in the film density and coordination number.

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

    International Nuclear Information System (INIS)

    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.

  9. Tuning the Photocatalytic Activity of Anatase TiO2 Thin Films by Modifying the Preferred <001> Grain Orientation with Reactive DC Magnetron Sputtering

    Directory of Open Access Journals (Sweden)

    B. Stefanov

    2014-08-01

    Full Text Available Anatase TiO2 thin films were deposited by DC reactive magnetron sputtering on glass substrates at 20 mTorr pressure in a flow of an Ar and O2 gas mixture. The O2 partial pressure (PO2 was varied from 0.65 mTorr to 1.3 mTorr to obtain two sets of films with different stoichiometry. The structure and morphology of the films were characterized by secondary electron microscopy, atomic force microscopy, and grazing-angle X-ray diffraction complemented by Rietveld refinement. The as-deposited films were amorphous. Post-annealing in air for 1 h at 500 C resulted in polycrystalline anatase film structures with mean grain size of 24.2 nm (PO2 = 0.65 mTorr and 22.1 nm (PO2 = 1.3 mTorr, respectively. The films sputtered at higher O2 pressure showed a preferential orientation in the <001> direction, which was associated with particle surfaces exposing highly reactive {001} facets. Films sputtered at lower O2 pressure exhibited no, or very little, preferential grain orientation, and were associated with random distribution of particles exposing mainly the thermodynamically favorable {101} surfaces. Photocatalytic degradation measurements using methylene blue dye showed that <001> oriented films exhibited approximately 30% higher reactivity. The measured intensity dependence of the degradation rate revealed that the UV-independent rate constant was 64% higher for the <001> oriented film compared to randomly oriented films. The reaction order was also found to be higher for <001> films compared to randomly oriented films, suggesting that the <001> oriented film exposes more reactive surface sites.

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

    International Nuclear Information System (INIS)

    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

  11. Impact of water quality on removal of carbamazepine in natural waters by N-doped TiO2 photo-catalytic thin film surfaces

    International Nuclear Information System (INIS)

    Highlights: ► N-doped TiO2 thin films have been deposited by sol–gel dip-coating. ► CBZ removal improved with increasing medium pH in the range of 5–9. ► DOC at a concentration of 5 mg/L resulted in an ∼20% reduction in CBZ removal. ► Alkalinity values of 100 mg/L as CaCO3 resulted in a 40% decrease in CBZ removal. ► Complete suppression of the photocatalytic process in wastewater effluent. -- Abstract: Photocatalytic experiments on the pharmaceutical pollutant carbamazepine (CBZ) were conducted using sol–gel nitrogen-doped TiO2-coated glass slides under a solar simulator. CBZ was stable to photodegradation under direct solar irradiation. No CBZ sorption to the catalyst surface was observed, as further confirmed by surface characterization using X-ray photoelectron spectroscopic analysis of N-doped TiO2 surfaces. When exposing the catalyst surface to natural organic matter (NOM), an excess amount of carbon was detected relative to controls, which is consistent with NOM remaining on the catalyst surface. The catalyst surface charge was negative at pH values from 4 to 10 and decreased with increasing pH, correlated with enhanced CBZ removal with increasing medium pH in the range of 5–9. A dissolved organic carbon concentration of 5 mg/L resulted in ∼20% reduction in CBZ removal, probably due to competitive inhibition of the photocatalytic degradation of CBZ. At alkalinity values corresponding to CaCO3 addition at 100 mg/L, an over 40% decrease in CBZ removal was observed. A 35% reduction in CBZ occurred in the presence of surface water compared to complete suppression of the photocatalytic process in wastewater effluent

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  13. Effect of dehydration rate on non-hydrolytic TiO2 thin film processing: Structure, optical and photocatalytic performance studies

    International Nuclear Information System (INIS)

    Highlights: → Clear transparent TiO2 thin film prepared using non aqua sol-gel processing. → The complexing agents plays significant role in the rate of dehydration due to hydrolysis. → Faster dehydration significantly affects visible light transmittance and other properties. → Diethanoalamine plays significant role in the crystallization and phase transformation. - Abstract: The influence of complexing agent diethanolamine (DEA) on the rate of dehydration due to hydrolysis in titania thin films prepared by non-aqua sol-gel process was investigated. The formation of complex with titanium precursor controls the rate of hydrolysis over wide range of temperature. The rate of hydrolysis with respect to complex formation and firing temperate was studied by using thermogravimetry and differential thermal analysis (TG-DTA). The role of complexing agent in the crystallization of anatase and phase transformation to rutile was studied by X-ray diffraction (XRD). Effect of complexing agent on the optical transmittance in the visible range was monitored by ultraviolet-visible absorption spectroscopy. Photocatalytic performance of the titania films was measured using methylene blue (MB) as the model contaminant. Mechanical characteristics such as hardness and adhesion of the film were rated by using scratch tests as per ASTM standards.

  14. Influence of TiO2 nanoparticles on the optical and structural properties of PPV thin films converted at low temperatures

    Directory of Open Access Journals (Sweden)

    B. Rostirolla

    2013-08-01

    Full Text Available In this work we studied the optical properties of poly(p-phenylene vinylene (PPV produced by the thermal conversion of a precursor polymer blended with a synthetic dye (Reactive Black 5. The production of PPV by this method decreases the overall time and cost of the process. We observed that the introduction of the dye resulted in an additional absorbance band near 550–700 nm, which can be beneficial to the photon harvesting capacity of the polymer if it is used as the donor material in a photovoltaic device. We studied how the optical and structures properties of this blend change when different quantities of TiO2 nanoparticles are introduced. For that, thin films were produced by the cast deposition of pre-PPV:dye:TiO2. The scanning electronic microscopic images showed that the inorganic semiconductor form large agglomerates of approximately 200 nm, indicating a very rough surface where the dye can be adsorbed. The analysis of photoluminescence and Raman peaks indicated a reduction of the mean conjugation length of the polymer chains in the presence of TiO2 nanoparticles.

  15. Low temperature deposition of TiO2 thin films on polyvinyl alcohol fibers with photocatalytical and antibacterial activities

    International Nuclear Information System (INIS)

    Fine particles of photoactive anatase-type TiO2 coated polyvinyl alcohol (PVA) fibers (TiO2/PVA) were prepared successfully via a simple dip-coating method. Tetrabutyl orthotitanate (TBOT) was hydrolyzed in presence of hydrolysis control agent tetrabutylammonium hydroxide (TBA)OH and the TiO2 fine particles were crystallized under microwave (MW) irradiation. The X-ray diffraction (XRD) and selected-area electron diffraction (SAED) analyses indicated that the fine particles obtained with MW irradiation have much higher crystallinity with a single phase anatase compared with the non-MW-treated solution. The continuous layers of titania were found on PVA fibers by the scanning electron microscopy (SEM) analysis. The fibers with anatase coatings showed high photocatalytic property on the photodegradation of methylene blue (MB) and high antibacterial activity

  16. Spectroscopic ellipsometry characterization of amorphous and crystalline TiO2 thin films grown by atomic layer deposition at different temperatures

    International Nuclear Information System (INIS)

    Highlights: • Refractive index was found to be increased from amorphous to the nanocrystalline films. • Refractive index was found to be inversely proportional with growth per cycle. • Large-grained anatase films showed lower refractive indices than the amorphous films. • Roughness was taken into consideration due to the columnar growths of crystalline films. - Abstract: TiO2 thin films of widely different structural and morphological characteristics were grown on Si (1 0 0) substrates using Atomic Layer Deposition (ALD) by varying the substrate temperature (Ts) in a wide range (50 °C ≤ Ts ≤ 400 °C). Spectroscopic ellipsometry (SE) measurements were carried out to investigate the effect of growth temperature on the optical properties of the films. Measured SE data were analyzed by considering double layer optical model for the sample together with the single oscillator Tauc-Lorentz dispersion relation. Surface roughness was taken into consideration due to the columnar growths of grains in crystalline films. The refractive index was found to be increased from amorphous (Ts ≤ 150 °C) to the nanocrystalline films (2500 < Ts ≤ 400 °C). The pronounced surface roughening for the large-grained anatase film obtained at the amorphous to crystalline phase transformation temperature of 200 °C, impeded SE measurement. The dispersions of refractive indices below the interband absorption edge were found to be strongly correlated with the single oscillator Wemple–DiDomenico (WD) model. The increase in dispersion energy parameter in WD model from disordered amorphous to the more ordered nanocrystalline films was found to be associated with the increase in the film density and coordination number

  17. Li-N doped and codoped TiO2 thin films deposited by dip-coating: Characterization and photocatalytic activity under halogen lamp

    Science.gov (United States)

    Hamden, Z.; Boufi, S.; Conceição, D. S.; Ferraria, A. M.; do Rego, A. M. Botelho; Ferreira, D. P.; Ferreira, L. F. Vieira; Bouattour, S.

    2014-09-01

    Li-, N-doped and codoped TiO2 powders and thin films, deposited on glass substrate using dip-coating method and Ti(OBu)4 as precursor, were prepared and their structural properties were investigated using grazing angle X-ray diffraction (GXRD), Raman spectroscopy, time resolved luminescence, X-ray photoelectron spectroscopy (XPS), ground state diffuse reflectance absorption and scanning electron microscopy (SEM). Unlike the powder samples, thin films with the same composition and calcination temperature exhibited lower crystallinity degree along with the prevalence of the anatase phase. Ground state diffuse reflectance absorption studies carried on the nanopowders have shown that both the Li and N dopants led to an increase of the band gap. XPS studies revealed differences in the binding energy of N in the presence and in the absence of Li, which was explained in terms of a modification in the chemical environment of N when Li is introduced. The photocatalytic activity of the ensuing film toward the degradation of aromatic amine pollutant revealed a huge enhancement upon doping with N or codoping with N and Li. This behavior is probably provide by a charge-transfer-complex mechanism in which neither the photocatalyst nor the organic compounds absorbs visible light by itself. The improvement in the photocatalytic properties occurred simultaneously with the increase of the lifetime of the charge carriers whenever N and Li were introduced at a level 2%.

  18. High-tunability and low-microwave-loss Ba0.6Sr0.4TiO3 thin films grown on high-resistivity Si substrates using TiO2 buffer layers

    Science.gov (United States)

    Kim, Hyun-Suk; Kim, Ho-Gi; Kim, Il-Doo; Kim, Ki-Byoung; Lee, Jong-Chul

    2005-11-01

    In this Letter, we report on high-tunability and low-microwave-loss properties of Ba0.6Sr0.4TiO3 (BST) thin films by use of atomic-layer-deposited TiO2 films as the microwave buffer layer between BST and high-resistivity Si substrate. The interdigital capacitor fabricated on BST films grown on TiO2/high resistivity Si (2kΩcm) substrates showed the much enhanced tunability value of 33.2% while retaining an appropriate Q factor, as compared to the tunability values of BST (21%) films grown on MgO single-crystal substrates and BST (8.2%) films grown on TiO2/normal Si (10Ωcm) substrates. The coplanar waveguide BST phase shifter fabricated on TiO2/high resistivity Si exhibited a phase shift of 95° and insertion loss of 3.09 dB at 15 GHz and an applied voltage of 50 V. ALD-grown TiO2 buffer layers enable the successful integration of BST-based microwave tunable devices onto high-resistivity Si wafers.

  19. 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

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    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 the activity under UV irradiation. Using the response surface methodology, RSM, based on a design of experiment, DOE, we are able to achieve a good understanding of the complex processes involved in the deposition of the thin films and their effect on the photocatalytic activity.

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

    OpenAIRE

    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...

  3. X-ray Spectroscopy of Ultra-thin Oxide/oxide Heteroepitaxial Films: A Case Study of Single-nanometer VO2/TiO2

    Energy Technology Data Exchange (ETDEWEB)

    Quackenbush, Nicholas F. [Binghamton Univ., NY (United States); Paik, Hanjong [Cornell Univ., Ithaca, NY (United States); Woicik, Joseph C. [National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Arena, Dario A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Schlom, Darrell G. [Cornell Univ. and Kavli Inst. at Cornell for Nanoscale Science, Ithaca, NY (United States); Piper, Louis F. J. [Binghamton Univ., NY (United States)

    2015-08-21

    Epitaxial ultra-thin oxide films can support large percent level strains well beyond their bulk counterparts, thereby enabling strain-engineering in oxides that can tailor various phenomena. At these reduced dimensions (typically < 10 nm), contributions from the substrate can dwarf the signal from the epilayer, making it difficult to distinguish the properties of the epilayer from the bulk. This is especially true for oxide on oxide systems. Here, we have employed a combination of hard X-ray photoelectron spectroscopy (HAXPES) and angular soft X-ray absorption spectroscopy (XAS) to study epitaxial VO2/TiO2 (100) films ranging from 7.5 to 1 nm. We observe a low-temperature (300 K) insulating phase with evidence of vanadium-vanadium (V-V) dimers and a high-temperature (400 K) metallic phase absent of V-V dimers irrespective of film thickness. Results confirm that the metal insulator transition can exist at atomic dimensions and that biaxial strain can still be used to control the temperature of its transition when the interfaces are atomically sharp. Generally, our case study highlights the benefits of using non-destructive XAS and HAXPES to extract out information regarding the interfacial quality of the epilayers and spectroscopic signatures associated with exotic phenomena at these dimensions.

  4. A simple spectrophotometric method for determination of the optical constants and band gap energy of multiple layer TiO2 thin films

    International Nuclear Information System (INIS)

    Using sol-gel processing, TiO2 films have been prepared on microscopic glass slides by dip-coating technique. From X-ray diffractometric (XRD) and X-ray photoelectron spectroscopic (XPS) measurements, it has been confirmed that the deposited films are an anatase form of stoichiometric TiO2. Using either normal incidence transmittance or normal incidence reflectance data, a simple method for determining both film refractive index, n(λ), and film thickness, d, has been proposed for a transparent film on a non-absorbing flat substrate. At same wavelength within visible region, a correlation between TS and TB has been established and verified. TS and TB represent the transmittances of single side and both sides coated films of same thickness, respectively, prepared at identical conditions. Average film thickness per coating at various withdrawal speeds (58-146 mm min-1) has been estimated. An empirical dispersion equation that describes the variation of n(λ) of TiO2 films in the wavelength (λ) range of ∼390-800 nm has been deduced. Band gap energy (Eg) has also been estimated for these films. It has been observed that Eg changes from ∼3.35 to 3.16 eV as the film thickness varies from ∼100 to 300 nm and it does not depend significantly upon film withdrawal speeds in the range 58-146 mm min-1

  5. 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

    Science.gov (United States)

    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.

  6. Methylene blue photoelectrodegradation under UV irradiation on Au/Pd-modified TiO2 films

    International Nuclear Information System (INIS)

    In this work TiO2 thin films were modified with gold/palladium (Au/Pd) bimetallic paticles by sputtering method. TiO2 films were deposited on ITO (SnO2:In) by Doctor Blade method and post-anneling. The properties of the films were studied through measurements of XRD (X-ray diffraction) and AFM (atomic force microscopy). The degradation of methylene blue was studied by UV-irradiated pure TiO2 and Au/Pd-modified TiO2 in aqueous solution. Langmuir-Hinshelwood model was used to obtain kinetic information. Photocatalytic study indicated that Au/Pd-modified TiO2 photocatalytic activity was better than TiO2 pure; the best half-life time for Au/Pd-modified TiO2 in photodegradation was 2.8 times smaller than TiO2 pure; finally the efficiency in methylene blue photodegradation was improved from 23% to 43% when Au/Pd-modified TiO2 films were used.

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

    International Nuclear Information System (INIS)

    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

  8. Optimization of Al2O3/TiO2 nanolaminate thin films prepared with different oxide ratios, for use in organic light-emitting diode encapsulation, via plasma-enhanced atomic layer deposition.

    Science.gov (United States)

    Kim, Lae Ho; Jeong, Yong Jin; An, Tae Kyu; Park, Seonuk; Jang, Jin Hyuk; Nam, Sooji; Jang, Jaeyoung; Kim, Se Hyun; Park, Chan Eon

    2015-12-23

    Encapsulation is essential for protecting the air-sensitive components of organic light-emitting diodes (OLEDs), such as the active layers and cathode electrodes. Thin film encapsulation approaches based on an oxide layer are suitable for flexible electronics, including OLEDs, because they provide mechanical flexibility, the layers are thin, and they are easy to prepare. This study examined the effects of the oxide ratio on the water permeation barrier properties of Al2O3/TiO2 nanolaminate films prepared by plasma-enhanced atomic layer deposition. We found that the Al2O3/TiO2 nanolaminate film exhibited optimal properties for a 1?:?1 atomic ratio of Al2O3/TiO2 with the lowest water vapor transmission rate of 9.16 10(-5) g m(-2) day(-1) at 60 C and 90% RH. OLED devices that incorporated Al2O3/TiO2 nanolaminate films prepared with a 1?:?1 atomic ratio showed the longest shelf-life, in excess of 2000 hours under 60 C and 90% RH conditions, without forming dark spots or displaying edge shrinkage. PMID:26661064

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

    Directory of Open Access Journals (Sweden)

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

    Science.gov (United States)

    Shah, Athar Ali; Umar, Akrajas Ali; Mat Salleh, Muhamad

    2016-01-01

    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.

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

    International Nuclear Information System (INIS)

    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

  12. Al2O3/TiO2 multilayer thin films grown by plasma enhanced atomic layer deposition for organic light-emitting diode passivation

    International Nuclear Information System (INIS)

    Aluminum oxide (Al2O3) and titanium dioxide (TiO2) films deposited on flexible polyethersulfone substrates by plasma-enhanced atomic layer deposition have been investigated for transparent barrier applications. The effects of the induced plasma power on the passivation properties were investigated as function of film thickness and substrate temperature. The optimum plasma power and substrate temperature were investigated through measurements of the refractive index and packing density of the Al2O3 and TiO2 films. In this research, three different barrier structures were investigated for the purpose of improving water vapor barrier characteristics. A low water vapor transmission rate of approximately 5 × 10−3 g/m2·day or below was achieved with two pairs of Al2O3/TiO2 stacks with a total stack thickness of 40 nm deposited at 80 °C. The passivation performance of the multilayer film was investigated using an organic light-emitting diode. The coated device lifetime was 267 h, which was 41 times longer than that of an uncoated sample. - Highlights: • Al2O3/TiO2 films deposited on polymer substrates by atomic layer deposition • The films were studied for transparent barrier applications. • 5 × 10−3 g/m2·day H2O transmission rate with two pairs of Al2O3/TiO2 stacks at 80 °C • Coated diode lifetime was 267 h, 41 times longer than that of an uncoated sample

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

    Science.gov (United States)

    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.

  14. Poly(vinyl chloride)-g-poly(2-(dimethylamino)ethyl methacrylate) graft copolymers templated synthesis of mesoporous TiO2 thin films for dye-sensitized solar cells

    International Nuclear Information System (INIS)

    A poly(vinyl chloride) (PVC) main chain was grafted with poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) containing a quaternary amine group using atom transfer radical polymerization. The successful synthesis of a PVC-g-PDMAEMA graft copolymer was confirmed by Fourier transform infrared, nuclear magnetic resonance, thermogravimetric analysis, and transmission electron microscopy. The PVC-g-PDMAEMA graft copolymer was used as a structure-directing agent (SDA) for the fabrication of a mesoporous thin film containing a titanium dioxide (TiO2) layer. To control the porosity of the resultant inorganic layer, the ratio of SDA to TTIP as well as the concentration of the solgel was varied. The structure and porosity of the mesoporous film were characterized by XRD and SEM analysis. The mesoporous TiO2 film fabricated on the FTO surface was used as a photoanode for the dye-sensitized solar cell (DSSC). DSSC performance was the greatest when using TiO2 film with a higher porosity and lower interfacial resistance. The highest energy conversion efficiency reached 3.2 % at 100 mW/cm2, which was one of the highest reported values for a quasi-solid-state DSSC with 600-nm-thick TiO2 film.

  15. Investigation on the structural, morphological and photochemical properties of spin-coated TiO2 and ZnO thin films prepared by sol-gel method

    Directory of Open Access Journals (Sweden)

    N. Mastali

    2013-03-01

    Full Text Available In this study, TiO2 and ZnO nanofilms were prepared by sol-gel spin-coating method. Nanofilms were characterized by X-ray Diffraction (XRD, Energy Dispersive Analysis of X-ray (EDX, Scanning Electron Microscopy (SEM and Field Emission Scanning Electron Microscopy (FE-ESM. Structural and morphological properties of nanofilms were investigated. The average crystalline size of TiO2 and ZnO nanoparticles which were obtained from the ignition of sols were obtained 80 and 50 nm, respectively. The morphological properties of nanofilms showed that the TiO2/ZnO nanocomposite film was strongly related to the steps of coating. Also, photocatalytic degradation of methylene blue on the surface of these nanofilms under UV light irradiation was studied and results were compared to each other.

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

    International Nuclear Information System (INIS)

    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

  17. Preparation of regularly structured nanotubular TiO2 thin films on ITO and their modification with thin ALD-grown layers

    Science.gov (United States)

    Tupala, Jere; Kemell, Marianna; Härkönen, Emma; Ritala, Mikko; Leskelä, Markku

    2012-03-01

    Nanotubular titanium dioxide thin films were prepared by anodization of titanium metal films evaporated on indium tin oxide (ITO) coated glass. A facile method to enhance the adhesion of the titanium film to the ITO glass was developed. An optimum thickness of 550 nm for the evaporated titanium was found to keep the film adhered to ITO during the anodization. The films were further modified by growing amorphous titania, alumina and tantala thin films conformally in the nanotubes by atomic layer deposition (ALD). The optical, electrical and physical properties of the different structures were compared. It was shown that even 5 nm thin layers can modify the properties of the nanotubular titanium dioxide films.

  18. Effect of total gas pressure and O2/N2 flow rate on the nanostructure of N-doped TiO2 thin films deposited by reactive sputtering

    International Nuclear Information System (INIS)

    N-doped TiO2 thin films have been deposited by reactive RF magnetron sputtering at different total gas pressures and varying O2/N2 gas flow rates at 300 °C. The thin film nanostructure has been studied by scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy (XPS). Increasing the deposition pressure leads to reduced crystallinity of the thin films and a higher N2 flow rate was required to incorporate N into the growing film. This is attributed to the lower energy ion bombardment of the surface and N adatom chemical reactivity being reduced at higher total gas pressures. Ar+ ion sputtering of the deposited N-doped TiO2 thin films has enabled a detailed XPS investigation of the surface and bulk N species to be performed. Adsorbed N species have been identified on all the deposited thin film surfaces, with the most prevalent adsorbed N species occurring at a binding energy of approximately 400 eV, shown to originate from atmospheric contamination, most probably N containing organic species. The bulk N content varies between 0.6 and 6.0 at.% and N is located predominantly at substitutional sites in the TiO2. The presence of interstitial N, in the form of NO species, has been identified by XPS in some thin films deposited at higher deposition pressures. Hence, varying the total gas pressure may provide a route for tailoring the location of N in the bulk structure. At higher N contents (> 3 at.%), TiN is found as a secondary phase within the bulk structure and the presence of TiN leads to a sharp reduction in the band gap. Post-deposition annealing of low N containing films results in an N-doped TiO2 single phase anatase structure. - Highlights: • N-doped TiO2 films were deposited by RF magnetron sputtering with different N%. • Incorporated N is mainly substitutional, interstitial is detected in some films. • TiN is formed at high deposition pressures. • N organic species (contamination) are adsorbed on the surfaces

  19. Optical properties of rare earth-doped TiO2 anatase and rutile thin films grown by pulsed-laser deposition

    International Nuclear Information System (INIS)

    Ln3+ (Ln = Tm, Eu and Yb) doped titanium dioxide anatase and rutile films have been grown by pulsed-laser deposition at 700 C under 0.1 mbar O2. By using c-cut (0001) Al2O3 sapphire or (100) LaAlO3 single crystal substrates, TiO2 films doped with Ln3+ are constituted with either highly oriented (200) rutile or (004) anatase, respectively. Energy transfer from TiO2 to Ln3+ is studied by photoluminescence spectroscopy with UV excitation (364 nm) under band gap excitation of the oxide matrix. It is demonstrated that Tm3+ dopant is not efficient as sensitizers. On the contrary, energy transfer from TiO2 to Eu3+ and Yb3+ occurs in both matrixes, which make this material suitable for down-shifting purpose. Results obtained for Yb3+ compared with our previous study on Nd3+ show that Nd3+ doped-rutile and Yb3+ doped-anatase are the more efficient combinations to convert UV to NIR photon. Finally, a cooperative conversion mechanism is suggested to explain the higher integrated photoluminescence intensity found in anatase Yb3+ rather than in rutile. - Highlights: Oriented anatase or rutile TiO2 films doped with 1%at. Tm, Eu, Yb or Nd are grown. The rare-earth-doped TiO2 films are transparent in the visible range. Anatase doped with Yb3+ and rutile doped with Nd3+, are promising for UV to NIR conversion

  20. Effect of ion bombardment on the structural and optical properties of TiO2 thin films deposited from oxygen/titanium tetraisopropoxide inductively coupled plasma

    International Nuclear Information System (INIS)

    Titanium dioxide films were deposited on silicon substrates from oxygen/titanium tetraisopropoxide inductively coupled radiofrequency plasmas in a helicon reactor operated at low temperature (< 150 °C) and low pressure (0.4 Pa). The effect of the ion energy (Ei), varied in the 15–175 eV range, on the morphology, microstructure and optical properties of the films is investigated. Scanning electron microscopy (SEM) shows that at low energy (Ei = 15 eV), the film exhibits a columnar morphology consisting of a bottom dense layer, an intermediate gradient layer and a top roughness layer. Increasing the ion energy results in more homogeneous films along the growth direction as confirmed by the in-situ kinetic ellipsometry measurements and post deposition spectroscopic ellipsometry data analysis. In addition, the atomic force microscopy (AFM) measurements reveal that the film top surface becomes smoother as Ei is increased. X-ray diffraction (XRD) diagrams show that only anatase is identified in the film deposited at 15 eV, whereas the complete phase transformation from anatase to rutile occurs at Ei = 75 eV. These results are in good agreement with the Fourier transform infrared spectroscopy (FTIR) spectra which also show that the hydroxyl groups absorbed in the films deposited at 15 eV, are greatly decreased for Ei ≥ 45 eV. Suitable structural models combined with the Tauc–Lorentz dispersion law have been found to accurately fit the spectroscopic ellipsometry experimental data. The results in good agreement with SEM and AFM measurements are also consistent with the structural properties evidenced by XRD and FTIR. The refractive index (n) can be increased significantly by increasing the ion energy from 15 eV to 75 eV, reaching a value of 2.49 at 1.96 eV. Upon increasing the ion energy above 75 eV n is shown to decrease due to micropores which are formed in the films. - Highlights: • TiO2 thin films deposited in inductively coupled plasma. • Low temperature anatase to rutile transition by ion energy control. • Appearance of micropores at high ion energies. • In situ ellipsometry performed both in kinetic and spectroscopic modes. • Structural and optical results are evidenced by ellipsometry analysis

  1. Synthesis and Annealing of Nanostructured TiO2 Films by Radio-Frequency Magnetron Sputtering

    Directory of Open Access Journals (Sweden)

    M.M. Hasan

    2009-01-01

    Full Text Available In this investigation, anatase TiO2 thin films were deposited on glass substrates at room temperature by RF magnetron sputtering at an elevated sputtering pressure of 3 Pa. The TiO2 films deposited at room temperature were annealed at different temperatures up to 873°K for 1 h. The TiO2 films were characterized by X-Ray Diffraction (XRD, Field-Emission Scanning Electron Microscopy (FESEM, Atomic Force Microscopy (AFM and UV-visible-NIR spectrophotometry. The XRD results reveal that the as-deposited film possess the anatase structure. Annealed TiO2 films show an insignificant change in crystallinity except of the fact that there is a slight increase for the film annealed at 600°C. The crystallite size increases from 44.5 to 48 nm with the increase of the annealing temperature. As-grown TiO2 film exhibits high visible transmittance with enhanced refractive index of 2.31 at a wavelength of 550 nm. The indirect optical band gaps of the as-deposited and annealed films have been estimated to be in the range of 3.39-3.42 eV. AFM observations reveal the compact and dense morphology of the as-deposited and annealed TiO2 thin films.

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

    International Nuclear Information System (INIS)

    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 PVTEG 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 photovoltaicthermoelectric generator (PVTEG) 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 PVTEG system using this thin-film filter is proposed and the benefits of the filter for hybrid solar power systems are demonstrated.

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

    Science.gov (United States)

    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.

  4. Rapid erasing of wettability patterns based on TiO2-PDMS composite films

    International Nuclear Information System (INIS)

    Research highlights: ? TiO2-PDMS composite films are prepared using the sol-gel method. ? The films show wettability conversion by irradiation with oxygen plasma. ? Hydrophobic-superhydrophilic patterns based on the TiO2-PDMS films are fabricated. ? The wettability patterns are rapidly erasable upon plasma irradiation for 1 s. - Abstract: TiO2-polydimethylsiloxane (TiO2-PDMS) composite films are prepared using the sol-gel method from a Ti(OBu)4-benzoylacetone solution containing PDMS. The prepared films are cured by irradiation with ultraviolet (UV) light. Structural changes in the films after UV irradiation are confirmed by UV-vis absorption experiments, which show that an absorption band characteristic of the benzoylacetonate chelate rings disappears. This finding is ascribed to structural changes associated with the dissociation of the chelate rings. The IR spectra of the thin films exhibit a broad absorption band after UV irradiation, indicating that a Ti-O-Ti network forms in the thin film. Contact angles are measured for the TiO2-PDMS thin films, showing wettability conversion from hydrophobic to superhydrophilic states by irradiation with oxygen plasma for 1 s. This phenomenon is explained by XPS experiments which reveal that the number of carbon atoms decreases, whereas the number of oxygen atoms increases on the surface of the TiO2-PDMS composite films. Finally, hydrophobic-superhydrophilic patterns are fabricated based on a patterned TiO2-PDMS composite film. The film displays a rapid change to superhydrophilicity over the whole film surface upon plasma irradiation for 1 s, which means that the wettability patterns are rapidly erasable.

  5. Pulsed Direct liquid Injection ALD of TiO2 Films Using Titanium Tetraisopropoxide Precursor

    Science.gov (United States)

    Avril, L.; Decams, J. M.; Imhoff, L.

    TiO2 thin films are grown by pulsed direct liquid injection atomic layer deposition with rapid thermal heating using titanium tetraisopropoxide and water vapor as precursors. The ALD growth rate is constant in the saturation zone range 35-47 ms at the temperature deposition of 280 °C. The TiO2 growth rate of 0.018 nm/cycle was achieved in a self-limited ALD mode. SEM and AFM analysis showed the as-deposited films have a smooth surface with a low roughness. XPS analysis exhibited the stoichiometry of TiO2 in the homogenous depth composition.

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

    International Nuclear Information System (INIS)

    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.

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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.

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

    International Nuclear Information System (INIS)

    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

  10. TiO2 and Fe-Doped TiO2 Thin Layers

    Czech Academy of Sciences Publication Activity Database

    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

  11. Pure and silver (2.5-40 vol%) modified TiO2 thin films deposited by radio frequency magnetron sputtering at room temperature: Surface topography, energy gap and photo-induced hydrophilicity

    International Nuclear Information System (INIS)

    Ag-TiO2 nanostructured thin films with silver volume fraction of 0-40% were deposited on silicon and quartz substrates by radio frequency (RF) magnetron sputtering. The phase structure, surface composition, surface topography, optical properties, and hydrophilicity of the films were characterized by X-ray diffractometer, X-ray photoelectron energy spectrometer, atomic force microscope, ultraviolet-visible spectrophotometer, and water contact angle apparatus. The relation of hydrophilic property and silver content was studied in detail. It was found that silver content influences microstructure of TiO2 thin films, and silver in the films is metallic Ag (Ag0). Hydrophilic behavior of the films increases with the increase of silver content up to 5 vol% Ag and then decreases. A suitable amount (around 5 vol% Ag) of silver addition can significantly enhance the hydrophilicity of TiO2 films. The hydrophilic behavior of the films is discussed in terms of the synergic effects of defective site, energy gap, surface roughness, and grain size.

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

    Science.gov (United States)

    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. free method for producing robust mesoporous films of nanocrystalline anatase TiO2 at temperatures of/or below 80 °C. The individual assembly of the mesoscopic particles forming ever-demonstrated high optical quality beads of TiO2 affords, with this simple methodology, efficient light capture and confinement into the photo-anode, which in flexible dye-sensitized solar cell technology translates into a remarkable power conversion efficiency of 7.2% under A.M.1.5G conditions.

  13. Pt Catalyst Supported within TiO2 Mesoporous Films for Oxygen Reduction Reaction

    International Nuclear Information System (INIS)

    In this study, dispersed Pt nanoparticles into mesoporous TiO2 thin films are fabricated by a facile electrochemical deposition method as electro-catalysts for oxygen reduction reaction. The mesoporous TiO2 thin films coated on the fluorine-doped tin oxide glass by screen printing allow a facile transport of reactants and products. The structural properties of the resulted Pt/TiO2 electrode are evaluated by field emission scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction, and X-ray photoelectron spectroscopy. Cyclic voltammetry measurements are performed to study the electrochemical properties of the Pt/TiO2 electrode. Further study demonstrates the stability of the Pt catalyst supported within TiO2 mesoporous films for the oxygen reduction reaction

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

    Science.gov (United States)

    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...

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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 m(2) g(-1)) than that of Co0.85Se nanofilms (55.17 m(2) g(-1)) and TiO2 nanoparticles (19.49 m(2) 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. PMID:26903086

  17. Silver Doped TiO2 Nanostructure Composite Photocatalyst Film Synthesized by Sol-Gel Spin and Dip Coating Technique on Glass

    OpenAIRE

    Mohammad Hossein Habibi; Mojtaba Nasr-Esfahani

    2008-01-01

    New composite films (P25SGF-MC-Ag, MPC500SGF-MC-Ag, and ANPSGF-MC-Ag) have been synthesized by a modified sol-gel method using different particle sizes of TiO2 powder and silver addition. Nanostructure TiO2/Ag composite thin films were prepared by a sol-gel spin and dip coating technique. while, by introducing methyl cellulose (MC) porous, TiO2/Ag films were obtained after calcining at a temperature of 500Co. The as-prepared TiO2 and TiO2/Ag films were characterized by X-ray diffractometr...

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

    International Nuclear Information System (INIS)

    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. TiO2 and Fe2O3 Films for Photoelectrochemical Water Splitting

    Directory of Open Access Journals (Sweden)

    Josef Krysa

    2015-01-01

    Full Text Available Titanium oxide (TiO2 and iron oxide (α-Fe2O3 hematite films have potential applications as photoanodes in electrochemical water splitting. In the present work TiO2 and α-Fe2O3 thin films were prepared by two methods, e.g., sol-gel and High Power Impulse Magnetron Sputtering (HiPIMS and judged on the basis of physical properties such as crystalline structure and surface topography and functional properties such as simulated photoelectrochemical (PEC water splitting conditions. It was revealed that the HiPIMS method already provides crystalline structures of anatase TiO2 and hematite Fe2O3 during the deposition, whereas to finalize the sol-gel route the as-deposited films must always be annealed to obtain the crystalline phase. Regarding the PEC activity, both TiO2 films show similar photocurrent density, but only when illuminated by UV light. A different situation was observed for hematite films where plasmatic films showed a tenfold enhancement of the stable photocurrent density over the sol-gel hematite films for both UV and visible irradiation. The superior properties of plasmatic films could be explained by ability to address some of the hematite drawbacks by the deposition of very thin films (25 nm consisting of small densely packed particles and by doping with Sn.

  20. TiO2 and Fe2O3 films for photoelectrochemical water splitting.

    Science.gov (United States)

    Krysa, Josef; Zlamal, Martin; Kment, Stepan; Brunclikova, Michaela; Hubicka, Zdenek

    2015-01-01

    Titanium oxide (TiO2) and iron oxide (α-Fe2O3) hematite films have potential applications as photoanodes in electrochemical water splitting. In the present work TiO2 and α-Fe2O3 thin films were prepared by two methods, e.g., sol-gel and High Power Impulse Magnetron Sputtering (HiPIMS) and judged on the basis of physical properties such as crystalline structure and surface topography and functional properties such as simulated photoelectrochemical (PEC) water splitting conditions. It was revealed that the HiPIMS method already provides crystalline structures of anatase TiO2 and hematite Fe2O3 during the deposition, whereas to finalize the sol-gel route the as-deposited films must always be annealed to obtain the crystalline phase. Regarding the PEC activity, both TiO2 films show similar photocurrent density, but only when illuminated by UV light. A different situation was observed for hematite films where plasmatic films showed a tenfold enhancement of the stable photocurrent density over the sol-gel hematite films for both UV and visible irradiation. The superior properties of plasmatic film could be explained by ability to address some of the hematite drawbacks by deposition of very thin films (25 nm) consisting of small densely packed particles and by doping with Sn. PMID:25584834

  1. Growth of TiO2 nanosheet-array thin films by quick chemical bath deposition for dye-sensitized solar cells

    Science.gov (United States)

    Zhu, Hu; Yang, Junyou; Feng, Shuanglong; Liu, Ming; Zhang, Jiansheng; Li, Gen

    2011-11-01

    Rutile TiO2 nanofilms, which were composed of many nanosheet-array domains with different orientations, were synthesized directly on fluorine-doped SnO2 conductive glass (FTO) substrates by a chemical deposition method in a short time in this paper. The average thickness of the nanosheets is about 10 nm; the nanosheets in each domain were parallel to each other and perpendicular to the substrate. The size and profile of the domains have a good correspondence to those of the FTO grains of the substrate, indicating a coherent nucleating and epitaxial growing nature of the films. The nanosheets split gradually and finally developed into nanofibers on prolonging the growing time to 20 h. Dye-sensitized solar cells, which were fabricated with the films, present an open-circuit voltage of 0.63 V and a short-circuit current of 7.02 mA/cm2, respectively.

  2. Microwave irradiation as an alternative source for conventional annealing: a study of pure TiO2, NiTiO3, CdTiO3 thin films by a sol gel process for electronic applications

    Science.gov (United States)

    Phani, A. R.; Santucci, S.

    2006-08-01

    The lower temperature and shorter timescale for microwave irradiation may be ascribed to the activating and facilitating effect of microwaves on solid-phase diffusion. Using the microwave-heating process, it is possible to achieve enhanced mechanical properties such as greater hardness, improved scratch resistance, and structure texturing. In the present investigation, thin films of pure TiO2 and their respective perovskite-structured thin films, namely NiTiO3 and CdTiO3, have been prepared by simple and cost-effective sol-gel processing on Si(100) substrates and subjected to irradiation with different microwave powers for 10 min. X-ray diffraction (XRD), scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS) techniques have been employed to characterize the structural, morphological and elemental composition of the films. It is evident that there is a dramatic change in the structural and morphological properties of the films irradiated in microwaves compared to conventional annealing at high temperature. A plausible mechanism for the formation of the anatase phase of TiO2 and perovskite structures with a rhombohedral phase formation at low microwave powers has also been discussed. This new innovative microwave heating could open a door for advanced technologies to cut process costs in the post-treatment of materials.

  3. Photoelectrochemical characterization and photocatalytic properties of mesoporous TiO2/ZrO2 films

    Directory of Open Access Journals (Sweden)

    Olga Linyucheva

    2006-02-01

    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 TiO2 originates from an anodic shift of the valence band edge potential. Catalytic activity of mesoporous TiO2 and TiO2/ZrO2 (5–50% of ZrO2 films in the processes of CrVI to CrIII photoreduction and 2,4-dinitroaniline photooxidation correlates with crystalline size and growth with increasing of specific surface area of the samples.

  4. Fabrication of TiO2 Thick Film for Photocatalyst from Commercial TiO2 Powder

    International Nuclear Information System (INIS)

    Photocatalytic activity of TiO2 thick film ceramics made of commercial TiO2 powder has been studied. The TiO2 powder was nano sized one that was derived from dried TiO2 suspension. The TiO2 suspension was made by pouring some blended commercial TiO2 powder into some amount of water. The paste of TiO2 was made by mixing the nano sized TiO2 powder with organic vehicle and glass frit. The paste was spread on a glass substrate. The paste was dried at 100 deg. C and heated at different temperatures (400 deg. C and 500 deg. C) for 60 minutes to produce thick film ceramics. The photocatalytic activity of these films was evaluated by measuring the concentration of a solution of methylene blue where the thick films were inside after being illuminated by UV light at various periods of times. The initial concentration of the methylene blue solution was 5 ppm. Structural analyses were carried out by X-ray diffraction (XRD). The XRD analyses showed that the produced thick film ceramic had mainly crystal structure of anatase. According to the photocatalytical data, it was known that the produced thick film ceramics were photocatalyst which were capable of decomposing an organic compound such as the methylene blue

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

    OpenAIRE

    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...

  6. Effect of Process Temperature and Reaction Cycle Number on Atomic Layer Deposition of TiO2 Thin Films Using TiCl4 and H2O Precursors: Correlation Between Material Properties and Process Environment

    Science.gov (United States)

    Chiappim, W.; Testoni, G. E.; de Lima, J. S. B.; Medeiros, H. S.; Pessoa, Rodrigo Sávio; Grigorov, K. G.; Vieira, L.; Maciel, H. S.

    2016-02-01

    The effect of process temperature and reaction cycle number on atomic layer-deposited TiO2 thin films onto Si(100) using TiCl4 and H2O precursors was investigated in order to discuss the correlation between the growth per cycle (GPC), film structure (crystallinity), and surface roughness as well as the dependence of some of these properties with gas phase environment such as HCl by-product. In this work, these correlations were studied for two conditions: (i) process temperatures in the range of 100-500 °C during 1000 reaction cycles and (ii) number of cycles in the range of 100-2000 for a fixed temperature of 250 °C. To investigate the material properties, Rutherford backscattering spectrometry (RBS), grazing incidence X-ray diffraction (GIXRD), and atomic force microscopy (AFM) techniques were used. Mass spectrometry technique was used to investigate the time evolution of gas phase species HCl and H2O during ALD process. Results indicate that the GPC does not correlate well with film crystallinity and surface roughness for the evaluated process parameters. Basically, the film crystallinity relies solely on grain growth kinetics of the material. This occurs due to higher HCl by-product content during each purge step. Furthermore, for films deposited at variable cycle number, the evolution of film thickness and elemental composition is altered from an initial amorphous structure to a near stoichiometric TiO2-x and, subsequently, becomes fully stoichiometric TiO2 at 400 cycles or above. At this cycle value, the GIXRD spectrum indicates the formation of (101) anatase orientation.

  7. TiO2 and Fe2O3 Films for Photoelectrochemical Water Splitting

    OpenAIRE

    Josef Krysa; Martin Zlamal; Stepan Kment; Michaela Brunclikova; Zdenek Hubicka

    2015-01-01

    Titanium oxide (TiO2) and iron oxide (α-Fe2O3) hematite films have potential applications as photoanodes in electrochemical water splitting. In the present work TiO2 and α-Fe2O3 thin films were prepared by two methods, e.g., sol-gel and High Power Impulse Magnetron Sputtering (HiPIMS) and judged on the basis of physical properties such as crystalline structure and surface topography and functional properties such as simulated photoelectrochemical (PEC) water splitting conditions. It was revea...

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

    Indian Academy of Sciences (India)

    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.

  9. 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

    International Nuclear Information System (INIS)

    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.

  10. Thermal properties of TiO2 films grown by atomic layer deposition

    International Nuclear Information System (INIS)

    We study the thermal properties of amorphous TiO2 thin films of various thicknesses t, grown by atomic layer deposition. The thermo-optic coefficient dn/dT and the temperature coefficient dρ/dT of film density ρ are determined from ellipsometric data in wavelength range 380 −5 °C−1 and dρ/dT = − 4.8 × 10−5g cm−3° C−1. - Highlights: ► We study thermal properties of TiO2 films grown by atomic layer deposition (ALD). ► dn/dT is negative for thin films and takes positive values for relatively thicker ones. ► Films are denser than ones grown by other techniques such as evaporation.

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

    Science.gov (United States)

    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

  12. Resistive Switching in ALD ZnO and TiO2 Films

    Science.gov (United States)

    Waggoner, Todd; Co, John

    2010-03-01

    Resistive switching in metal oxide thin films has recently become a major scientific interest due to the possibility of producing low power, non-volatile resistive random access memory (ReRAM). Theories proposed for the switching mechanism typically involve the migration of oxygen vacancies under an applied electric field. Resulting from local increases in vacancy concentration, conducting filaments can form between device electrodes. The process is reversible by either applying a stronger voltage bias across the device to burn out the filaments or by reversing the applied field. This allows for the design of devices with unipolar or bipolar operation. A material comparison of ZnO and TiO2 thin films grown by atomic layer deposition (ALD) demonstrate different switching behavior in our devices. ALD TiO2 films have been prepared in the past but results typically show a wide variance. Here ZnO and TiO2 are directly compared utilizing Al electrodes. So far most work has been done using Pt electrodes on TiO2 thin films. Investigations show that device yield, performance, cycle endurance, and stability appear to differ significantly as a result of the chosen dielectric.

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

    International Nuclear Information System (INIS)

    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.

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

    International Nuclear Information System (INIS)

    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

  15. Surface plasmon resonance caused by gold nanoparticles formed on sprayed TiO2 films

    International Nuclear Information System (INIS)

    Titania films covered by gold nanoparticles are prepared by combination of spray pyrolysis and spin-coating methods. Proposed combination of techniques is prospective for photovoltaic coatings with plasmonic properties. The prepared TiO2 films with Au nanoparticles demonstrate variation in size of the gold nanocrystallites from 36 to 56 nm depending on the concentration of the HAuCl4∙ 3H2O solution and plasmonic light extinction in the spectral range of 600–650 nm. It is shown that gold nanocrystallites enhance Raman scattering from the underlying thin TiO2 film. - Highlights: • TiO2 thin films with Au-nanoparticles were produced by chemical solution methods. • The size and shape of Au-nanoparticles are controlled by the [HAuCl4∙ 3H2O]. • Plasmon light extinction was tuned from 600 to 650 nm by changing [HAuCl4∙ 3H2O]. • Raman scattering intensity of TiO2 films is enhanced by the Au-nanoparticles

  16. The influence of TiO2 powder and film on the photodegradation of methyl orange

    International Nuclear Information System (INIS)

    Recent investigation has showed that the semiconductor nano-powder or thin film, such as titanium dioxide suspended in water, can utilize ultraviolet light for photocatalytic oxidation of organic pollutants, such as dyes. The photocatalytic activity of TiO2 (powder or thin film) was tested in the reaction of photodegradation of methyl orange (MO). The effect of the initial concentration of dye, the pH, the amount and the type of TiO2 have been investigated. The films were prepared by doctor blade technique, and were annealed in air at various temperatures ranging from 300 to 500 deg. C. The thermal treatment increases the surface roughness of thin films. The best film (without fissures), with higher pores and small grains (150 nm) was the annealed one at 500 deg. C. The correlation between the measured contact angle and the films roughness estimated from atomic force microscopy (AFM) shows that a low contact angle (wetting behavior) corresponds to a higher porosity (a fractured structure, rich in edges and corners), and consequently to high surface energy. Kinetic analyses indicate that the photodegradation rates of dyes can usually be approximated as first-order kinetics for degradation mechanisms. Adsorption is a prerequisite for the TiO2-assisted photodegradation, and the extent of degradation has been discussed in terms of the Langmuir-Hinshelwood model. Thin-film coating of photocatalyst may solve the problems of leaching and separation. At a low concentration of MO (0.0125 mM) the efficiency of MO photodegradation is comparable in the case of thin film and powder of TiO2

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

    DEFF Research Database (Denmark)

    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...

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

    International Nuclear Information System (INIS)

    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

  19. Wet Etching of TiO2-Based Precursor Amorphous Films for Transparent Electrodes

    Science.gov (United States)

    Ohkubo, Junpei; Hirose, Yasushi; Sakai, Enju; Nakao, Shoichiro; Hitosugi, Taro; Hasegawa, Tetsuya

    2011-01-01

    We investigated wet etching of Nb-doped anatase TiO2 (TNO) transparent conducting thin films and their precursors in an amorphous phase deposited by rf sputtering on glass substrates. The polycrystalline TNO films showed a very low etching rate of less than 0.06 nm/min in concentrated sulfuric acid (H2SO4) even at elevated temperatures up to 95 °C. In contrast, H2SO4 etched the precursor films at a rate of 1.4 nm/min at 95 °C. The etching rate of the amorphous films followed the Arrhenius equation, leading us to conjecture that a much higher etching rate of ˜230 nm/min can be achieved at 170 °C. These results indicate that wet-etching of precursor amorphous films prior to crystallization represents a practical and low-cost lithographic technique for patterning TiO2-based transparent electrodes.

  20. Improvement of (004) texturing by slow growth of Nd doped TiO2 films

    International Nuclear Information System (INIS)

    In this work, we present preferred (004) texturing of sputter deposited titanium dioxide (TiO2) films on glass substrates as a consequence of Nd doping at very slow growth rate. Nd concentration was varied from 0.0 to 2.0 atomic percent (at. %) in TiO2 thin films deposited under identical growth conditions, i.e., the growth rate of 0.6 Å/s and at 500 °C. At 2 at. % Nd, complete texturing along (004) plane was observed, as indicated by the X-ray diffraction analyses. Morphology of the deposited TiO2 films from pure to 2 at. % Nd doped TiO2 films showed faceted to planar growth. Visualization of electrical and structural analysis (VESTA) software revealed that the change in the morphology was due to preferential growth in (004) orientation. Raman spectroscopy highlighted the phonon confinement in the Eg mode, and a red shift was observed due to an increase in the anti-symmetry in bonding with increased Nd concentration. XPS results confirmed the variation in oxygen vacancy concentration along with the reduction of Ti and Nd valance states with the change in the dopant concentration. Our experiments confirmed that the substitution of Nd at Ti sites was responsible for texturing in (004) orientation and this was possible by growing films at a very slow rate.

  1. Double layer films based on TiO2 and NiOx for gas detection

    International Nuclear Information System (INIS)

    Highlights: • Double layer films based on TiO2 and NiOx for gas detection were studied. • Structural, compositional and morphological properties were investigated. • XPS spectra of TiO2 and NiOx were identified. • P- and n-type of response to hydrogen were presented. • Inversion of conductivity response type was confirmed. - Abstract: Double layer films based on TiO2 and NiOx for gas detection were studied. Two layouts with opposite position of functional films were deposited via DC magnetron sputtering method and annealed at 600 °C. The compositional, structural, morphological, electrical and gas sensing parameters were investigated. The depth profiles and the chemical state of the thin films elements were explored by X-ray photoelectron spectroscopy (XPS). Differences between the surface and subsurface NiOx were confirmed. In this way the formation of surface oxides and subsurface metallic Ni were observed. The structural changes and polycrystalline character were noticed by X-ray diffraction (XRD). The atomic force microscopy (AFM) revealed nanocrystalline character of the examined surfaces (both layouts). Different position of TiO2 and NiOx functional films brought difference in the type of response to reducing gas. Moreover, inversion of response type due to different H2 concentrations was confirmed

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

    Science.gov (United States)

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

    2016-01-01

    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. forming ever-demonstrated high optical quality beads of TiO2 affords, with this simple methodology, efficient light capture and confinement into the photo-anode, which in flexible dye-sensitized solar cell technology translates into a remarkable power conversion efficiency of 7.2% under A.M.1.5G conditions. PMID:26911529

  3. Up-conversion luminescence application in Er3+: TiO2 thin film prepared by dip coating sol-gel route

    International Nuclear Information System (INIS)

    Sol-gel derived nano-crystalline titanium dioxide films doped with 1 up to 5% Er3+ ions were prepared by dip coating sol-gel method. The coating sol was obtained by hydrolysis of Ti(OC4H9)4 in ethanol/HCI solution. The FT-Raman and the X-ray diffraction (XRD) were carried out to determine the crystal structure of the prepared samples. The morphology SEM and the cross-sectional of the film were used to characterize the microstructure and the thickness of the prepared film. It is shown that relative homogeneous, crack-free and transparent film was achieved via dipping process at 500 deg C. After the excitation with laser diode at wavelength 808 nm, visible (Vis) and infrared (IR) up-conversion emissions were evidenced in the thin film samples under investigation. The up-conversion was found to depend strongly on the Er3+ ion concentrations. The visible emission was found to be at 540, 560, 590 and 640 nm for thin film. They are attributed to intra-4f transition of Er3+ ions and assigned to the (2H11/2 + 4S3/2) and 4F9/2, which are populated through excited state absorption (ESA) for 808 nm excitation. (author)

  4. Influence of Ti top electrode thickness on the resistive switching properties of forming free and self-rectified TiO2−x thin films

    International Nuclear Information System (INIS)

    The memory performance of titanium oxide (TiO2−x)-based resistive memories containing an ultra thin reactive Ti top electrode can be greatly enhanced. Very good switching memory characteristics were demonstrated for an Au/Ti/TiO2−x/Au/SiO2/Si structure with the insertion of a Ti nanolayer at the Au/TiO2−x interface. Due to the superb ability of Ti to absorb oxygen atoms from the dielectric matrix, a large amount of oxygen vacancies is created, which are crucial for the stable function of the memory devices. As the Ti thickness increases, a thick interfacial layer is created, which degrades the resistive switching behavior. The induced interface thickness is found also to affect the fluctuation of the ON/OFF processes. The very good switching characteristics which were recorded for the devices containing Ti as top electrode, denote the direct impact that Ti has on the oxygen vacancy density. Oxygen vacancy distribution is also found to be directly associated with the filaments' diameter. Thus, the resistive switching mechanism is proposed to be associated with the formation/rupture of oxygen vacancy-based conducting filaments at the Ti/TiO2−x interface. Self-rectifying characteristics were also recorded for all samples in the low resistance states. Conduction mechanism analysis revealed that trap-assisted-tunneling is the dominant conduction mechanism, which also strongly affects the distribution of the current during SET process. - Highlights: • Direct impact of Ti top electrode (TE) thickness on the switching effect • Best switching results with 4 nm Ti TE • The crucial role of oxygen vacancies in the switching performance is highlighted. • Promising multilevel, forming-free and self-rectified switching performance

  5. 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

    International Nuclear Information System (INIS)

    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

  6. Caracterizacin de pelculas serigrficas de TiO2/alginato / Characterization of TiO2/alginate screenprinting films

    Scientific Electronic Library Online (English)

    M.A., Soto-Borbn; V.M., Snchez-Corrales; M.E., Trujillo-Camacho.

    Full Text Available En este trabajo se presentan los resultados de la caracterizacin de pelculas serigrficas formadas por TiO2 y alginato soportadas sobre sustratos de vidrio, aprovechando las propiedades adherentes/adsorbentes del biopolmero, con la finalidad de aplicarlas en la degradacin fotocataltica de conta [...] minantes. El anlisis de este material se realiz mediante la caracterizacin estructural, qumica y ptica de pelculas de compositos de TiO2/alginato elaboradas en una proporcin 90/10 en peso, mediante el empleo de las tcnicas de perfilometra, DRX, SEM, EDS, FT-IR y UV-Vis. Se lograron pelculas homogneas con un espesor controlado por el grosor de la malla serigrfica, con excelente adherencia a sustratos de vidrio y una mejor dispersin de las partculas de TiO2. Al aplicarse en la remocin de los tintes Methyl violeta 2B y Safranina O el desempeo de la pelcula de TiO2/alginato puede ser similar al del TiO2 solo. Abstract in english In this paper we report the characterization of screen printing films formed by TiO2 and a natural polymer (alginate) supported on glass substrates; in order to take advantage of the adhesive/adsorbents biopolymer properties, achieve a better semiconductor dispersion and a better adhesion to the sub [...] strate. The analysis of this material was accomplished by structural characterization of chemical and optical films of TiO2/alginato composites prepared in a ratio 90/10 by weight, by employing techniques such as profilometry, XRD, SEM, EDS, FT-IR and UV-Vis. When applied to the removal of Methyl Violet 2B (MV-2B) and Safranin O dyes, these films exhibited the same performance as TiO2 alone.

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

    Science.gov (United States)

    Rizwan Saleem, Muhammad; Honkanen, Seppo; Turunen, Jari

    2014-06-01

    Thin, amorphous, high index, dense, low scattering & 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.

  8. TiO2 films prepared by micro-plasma oxidation method for dye-sensitized solar cell

    International Nuclear Information System (INIS)

    Nanocrystalline TiO2 films are widely investigated as the electrodes of dye-sensitized solar cell(s) with different preparation methods. In this paper, thin titanium dioxide films have been prepared on titanium plates by the micro-plasma oxidation method in the sulfuric acid solution. The thin TiO2 films were sensitized with a cis-RuL2(SCN)2.2H2O (L = cis-2,2'-bipyridine-4,4'-dicarboxylic acid) ruthenium complex and implemented into a dye-sensitized solar cell configuration. The influence of reaction current density (10, 15, 20, 25 and 30 A dm-2) on the structural and the surface morphology of the films was investigated by X-ray diffraction, scanning electron microscopy, atom force microscopy and X-ray photoelectricity spectroscopy. Impedance analysis for dye-sensitized solar cells was carried out by electrochemical impedance spectroscopy. The results show that the rise of current density leads to the increase in the amount of rutile and the thickness of the TiO2 film, which makes the TiO2 films have different photovoltages and photocurrents. The relatively higher photoelectricity properties were obtained in the TiO2 films prepared at a current density of 20 A dm-2. The open-circuit voltage and the short-circuit current are 605 mV and 165 μA cm-2, respectively

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

    Science.gov (United States)

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

    2016-01-01

    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. < 100 °C) renders up-to-date deposition processes unsuited to flexible plastic supports or to smart textile fibres, thus limiting these wearable and easy-to-integrate emerging technologies. Here, we present a very versatile template-free method for producing robust mesoporous films of nanocrystalline anatase TiO2 at temperatures of/or below 80 °C. The individual assembly of the mesoscopic particles forming ever-demonstrated high optical quality beads of TiO2 affords, with this simple methodology, efficient light capture and confinement into the photo-anode, which in flexible dye-sensitized solar cell technology translates into a remarkable power conversion efficiency of 7.2% under A.M.1.5G conditions. PMID:26911529

  10. Real-time investigation on photocatalytic oxidation of gaseous methanol with nanocrystalline WO3TiO2 composite films

    International Nuclear Information System (INIS)

    Here we report on our investigation on photocatalytic oxidation (PCO) of gaseous methanol with WO3TiO2 composite films. WO3 and WO3TiO2 composite thin films were prepared by drop casting method. PCO of gaseous methanol and hydrogen generation process on platinum loaded WO3TiO2 composite thin films in high vacuum were investigated using a home-made reactor with a six-channel quadrupole mass spectrometer at real-time scale under UVA (300400 nm) light illumination. In the case of Pt loaded WO3 thin films, PCO of gaseous methanol proceeds through intermediates viz. formaldehyde, CO and finally to CO2 and H2. PCO of gaseous methanol occurs via direct hole transfer over Pt loaded WO3 thin films. On the other hand, PCO of gaseous methanol over Pt loaded WO3TiO2 composite thin films proceeds with competitive direct and indirect hole transfer reactions. Our real-time analysis of gas phase photocatalysis realized the identification of direct and indirect hole transfer processes and the reaction intermediates thereof.

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

    International Nuclear Information System (INIS)

    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

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

    Directory of Open Access Journals (Sweden)

    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.

  13. Study of structure of the TiO2MoO3 bilayer films by Raman spectroscopy

    International Nuclear Information System (INIS)

    Highlights: TiO2MoO3 bilayer thin films were easily prepared by dip-coating technique. Ti and Mo metallo-organic compounds were used as source of its respective oxide. TiO2 in anatase phase and orthorhombic phase of ?-MoO3 were identified. The bilayer structure was investigated by Raman spectroscopy. - Abstract: In this work, TiO2MoO3 films were easily prepared by dip-coating technique and metallo-organic decomposition process (MOD). Raman analyses indicate the formation of TiO2 in anatase phase and orthorhombic phase of ?-MoO3. It was observed that the Raman bands intensities attributed to TiO2 and MoO3 oxides were dependent on the number of decompositiondeposition cycles (DDC). The different number of DDC generates films with different thicknesses and the Raman signal was sensitive to this variation. Raman analyses provided qualitative information about the bilayer structure of the bi-component TiO2MoO3 films, which was confirmed by scanning electron microscopy. In this direction, the dip-coating technique and MOD process can be an efficient strategy to facile preparation of many samples to be used in applications

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

    Indian Academy of Sciences (India)

    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.

  15. Influence of operating parameters on surface properties of RF glow discharge oxygen plasma treated TiO2/PET film for biomedical application

    International Nuclear Information System (INIS)

    In this paper, a thin transparent titania (TiO2) film was coated on the surface of flexible poly(ethylene terephthalate) (PET) film using the sol–gel method. The surface properties of the obtained TiO2/PET film were further improved by RF glow discharge oxygen plasma as a function of exposure time and discharge power. The changes in hydrophilicity of TiO2/PET films were analyzed by contact angle measurements and surface energy. The influence of plasma on the surface of the TiO2/PET films was analyzed by atomic force microscopy (AFM) as well as the change in chemical state and composition that were investigated by X-ray photo electron spectroscopy (XPS). The cytotoxicity of the TiO2/PET films was analyzed using human osteoblast cells and the bacterial eradication behaviors of TiO2/PET films were also evaluated against Staphylococcus bacteria. It was found that the surface roughness and incorporation of oxygen containing polar functional groups of the plasma treated TiO2/PET films increased substantially as compared to the untreated one. Moreover the increased concentration of Ti3+ on the surface of plasma treated TiO2/PET films was due to the transformation of chemical states (Ti4+ → Ti3+). These morphological and chemical changes are responsible for enhanced hydrophilicity of the TiO2/PET films. Furthermore, the plasma treated TiO2/PET film exhibited no citotoxicity against osteoblast cells and antibacterial activity against Staphylococcus bacteria which can find application in manufacturing of biomedical devices. - Graphical abstract: Mechanism of plasma treatment on the surface of TiO2/PET films. - Highlights: • Investigated the surface properties of TiO2/PET films modified by O2 plasma • Studied the effect of operating parameters on surface properties of TiO2/PET films • Mechanism of the plasma treatment on TiO2/PET was clearly investigated. • Utilized various characterization techniques for analyzing the O2 plasma treated films • Examined antibacterial activity and cytotoxicity of the TiO2/PET films

  16. Optical, electrical and dielectric properties of TiO 2-SiO 2 films prepared by a cost effective sol-gel process

    Science.gov (United States)

    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.

  17. Microstructure of Nitrogen and Sulfur Co-doped Mesoporous TiO2 Film and its Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    LI Hui,WANG Jin-Shu,LI Hong-Yi,YIN Shu,SATO Tsugio

    2009-09-01

    Full Text Available Using Ti(OBun4 as the inorganic precursor, Pluronic F127 as the templating agent, and thiourea as the additive, mesoporous anatase TiO2 thin films were prepared through sol-gel method coupled with evaporationª²induced self-assembly (EISA process. Scanning electron microscope, X-ray photoelectron spectra, N2 adsorption-desorption, X-ray diffraction, and UV-Vis spectra were used to characterize the as-synthesized mesoporous TiO2 materials. It is found that, apart from doping N, S elements into the TiO2 lattice, the mesostructure of the TiO2 thin films is changed by adding thiourea into the reactive solution. When the mole ratio of thiourea to Ti(OBun4 is 2.5%, the pore size of the synthesized mesostructured TiO2 reaches 12.4nm, and the mesoporous TiO2 sample shows the best UV photocatalytic activity in the degradation of the methyl organge (MO. When the mole ratio of thiourea to Ti(OBun4 is 5%, the absorption edge of the as-synthesized sample can be extended from 380nm to 520nm, and the sample exhibits the best visible photo catalytic activity in decomposing the Rhodamine B (RhB.

  18. Photocatalytic Activity of Hierarchically Structured TiO2 Films Synthesized by Chemical Vapor Deposition

    OpenAIRE

    Heon Lee; Sung Hoon Park; Young-Kwon Park; Sun-Jae Kim; Byung-Hoon Kim; Jaehong Lee; Sang-Chul Jung

    2014-01-01

    Hierarchically structured TiO2 photocatalyst films were synthesized using low-pressure metal-organic chemical vapor deposition (LPMOCVD) method to examine their photocatalytic activity. The thickness of the TiO2 films increased proportionally with increasing deposition time. The TiO2 film synthesized at 773?K showed a hierarchical structure composed of vertically grown laminar (112)-oriented anatase crystals. With increasing deposition time, the grain became larger and the morphology became s...

  19. Antibacterial effect of silver modified TiO2/PECVD films

    Science.gov (United States)

    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.

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

    OpenAIRE

    Othman, Siti Hajar; Abd Salam, Nurul Raudhah; Zainal, Norhazlizam; Kadir Basha, Roseliza; Rosnita A. Talib

    2014-01-01

    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 ...

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

    International Nuclear Information System (INIS)

    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

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

    OpenAIRE

    Pulgarin, C.; 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...

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

    International Nuclear Information System (INIS)

    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 studies revealed that the fabricated thin films could be repeatedly used for up to ten times without affecting the photocatalytic activity of the films. The findings of the present study are very useful for the treatment of wastewaters contaminated with pesticides.

  4. Influence of porous morphology on optical dispersion properties of template free mesoporous titanium dioxide (TiO2) films

    International Nuclear Information System (INIS)

    This paper focuses the influence of porous morphology on the microstructure and optical properties of TiO2 films prepared by different sol concentration and calcination temperatures. Mesoporous TiO2 thin films were prepared on the glass substrates by sol-gel dip coating technique using titanium (IV) isopropoxide. Porous morphology of the films can be regulated by chemical kinetics and is studied by scanning electron microscopy. The optical dispersion parameters such as refractive index (n), oscillator energy (Ed), and particle co-ordination number (Nc) of the mesoporous TiO2 films were studied using Swanepoel and Wemple-DiDomenico single oscillator models. The higher precursor concentration (0.06 M), films exhibit high porosity and refractive index, which are modified under calcination treatment. Calcinated films of low metal precursor concentration (0.03 M) possess higher particle co-ordination number (Nc = 5.05) than that of 0.06 M films (Nc = 4.90) due to calcination at 400 deg. C. The lattice dielectric constant (E∞) of mesoporous TiO2 films was determined by using Spintzer model. Urbach energy of the mesoporous films has been estimated for both concentration and the analysis revealed the strong dependence of Urbach energy on porous morphology. The influence of porous morphology on the optical dispersion properties also has been explained briefly in this paper

  5. Structural and magnetic properties of Mn-doped anatase TiO2 films synthesized by atomic layer deposition

    Science.gov (United States)

    Sellers, Meredith C. K.; Seebauer, Edmund G.

    2011-08-01

    Mn-doped anatase TiO2 (Mn: 1.2, 2.4 at%) thin films were grown on Si(100) via atomic layer deposition (ALD). The synthesis utilized Ti(OCH(CH3)2)4 and H2O as ALD precursors and Mn(DPM)3 as a dopant source. X-ray photoelectron spectroscopy measurements indicate that Mn is successfully doped in the TiO2 matrix and reveal information about film composition and elemental chemical states. Microstructure, crystallinity, and density were investigated with scanning electron microscopy, X-ray diffraction, and X-ray reflectivity. All ALD-synthesized films exhibited room-temperature ferromagnetism; the microstructure, density, and magnetic field-dependent magnetization of the TiO2 varied with the concentration of Mn. ALD permits precise composition and thickness control, and much higher process throughput compared to alternative techniques.

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

    International Nuclear Information System (INIS)

    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

  7. Investigation into the photo-induced change in wettability of hydrophobized TiO 2 films

    Science.gov (United States)

    Risse, Gunter; Matys, Sabine; Böttcher, Horst

    2008-07-01

    The photo-induced change in wettability of hydrophobized TiO 2 films has been investigated for steel coated with acidic TiO 2 nanosols containing varying concentrations of dispersed nanocrystalline titania, such as Degussa P25. The photo-induced change in wettability was evaluated by measuring the time-dependent drop of water contact angle (WCA) after samples had been soaked in either n-octyltriethoxysilane (OTS) or decanoic acid (DA). TiO 2 films treated in this way exhibit superhydrophobic behaviour, with WCA greater than 160°. After radiation with UV (black light), the superhydrophobic properties are transformed into superhydrophilic properties, with WCA of almost 0°. As P25 content and layer thickness increase, high rates of photo-induced change are found, but a moderate calcination regime is required. On the other hand, hardness and E modulus pass through a maximum at 25 wt% P25, so that a P25 content between 25 and 50 wt% is the optimum for practical uses. With such stable coatings, wettability can be controlled over a wide range, and the switch between hydrophobic and hydrophilic states can be carried out repeatedly when DA is used as the hydrophobizing agent. Use of a low calcination temperature (450 °C) for the intermediate annealing of the single layers in multilayer coatings and a short final sintering step at a relatively high temperature (e.g. 630 °C for 10 min) allow the preparation of relatively thin TiO 2 films on steel with a high photoactivity.

  8. Investigation into the photo-induced change in wettability of hydrophobized TiO2 films

    International Nuclear Information System (INIS)

    The photo-induced change in wettability of hydrophobized TiO2 films has been investigated for steel coated with acidic TiO2 nanosols containing varying concentrations of dispersed nanocrystalline titania, such as Degussa P25. The photo-induced change in wettability was evaluated by measuring the time-dependent drop of water contact angle (WCA) after samples had been soaked in either n-octyltriethoxysilane (OTS) or decanoic acid (DA). TiO2 films treated in this way exhibit superhydrophobic behaviour, with WCA greater than 160 deg. After radiation with UV (black light), the superhydrophobic properties are transformed into superhydrophilic properties, with WCA of almost 0 deg. As P25 content and layer thickness increase, high rates of photo-induced change are found, but a moderate calcination regime is required. On the other hand, hardness and E modulus pass through a maximum at 25 wt% P25, so that a P25 content between 25 and 50 wt% is the optimum for practical uses. With such stable coatings, wettability can be controlled over a wide range, and the switch between hydrophobic and hydrophilic states can be carried out repeatedly when DA is used as the hydrophobizing agent. Use of a low calcination temperature (450 deg. C) for the intermediate annealing of the single layers in multilayer coatings and a short final sintering step at a relatively high temperature (e.g. 630 deg. C for 10 min) allow the preparation of relatively thin TiO2 films on steel with a high photoactivity

  9. Magnetic nanocomposite thin films of BaFe12O19 and TiO2 prepared by sol-gel method

    International Nuclear Information System (INIS)

    The composite films with different weight ratio of barium ferrite to titanium dioxide are successfully prepared using sol-gel method for the first time. The morphology, crystal structure and magnetic properties of composite films are investigated with atomic force microscopy, X-ray diffraction and vibrating sample magnetometry. The results show that the composite films are uniform with no microcracks. The grain diameters are less than 100 nm. With the increase of barium ferrite, the grain diameter decreases. The composite films are composed of M-type hexagonal barium ferrite and rutile titanium dioxide. The composite films possess the excellent magnetic properties. The specific saturation magnetization and coercivity reach 18.3 emu/g and 3350 Oe, respectively. The application of composite films in magnetic recording and electromagnetic absorption fields is promising

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

    International Nuclear Information System (INIS)

    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

  11. Silver Doped TiO2 Nanostructure Composite Photocatalyst Film Synthesized by Sol-Gel Spin and Dip Coating Technique on Glass

    Directory of Open Access Journals (Sweden)

    Mohammad Hossein Habibi

    2008-04-01

    Full Text Available New composite films (P25SGF-MC-Ag, MPC500SGF-MC-Ag, and ANPSGF-MC-Ag have been synthesized by a modified sol-gel method using different particle sizes of TiO2 powder and silver addition. Nanostructure TiO2/Ag composite thin films were prepared by a sol-gel spin and dip coating technique. while, by introducing methyl cellulose (MC porous, TiO2/Ag films were obtained after calcining at a temperature of 500Co. The as-prepared TiO2 and TiO2/Ag films were characterized by X-ray diffractometry, and scanning electron microscopy to reveal the structural and morphological differences. In addition, the photocatalytic properties of these films were investigated by degrading methyl orange (MO under UV irradiation. After 500Co calcination, the microstructure of MC-TiO2 film without Ag addition exhibited a microstructure, while significant sintering effect was noticed with Ag additions and the films exhibited a porous microstructure. Nanostructure anatase-phase TiO2 can be observed with respect to the sharpening of XRD diffraction peaks. The photodegradation of porous TiO2 deposited with 5×10−4 mol Ag exhibited the best photocatalytic efficiency, where 69% methyl orange can be decomposed after UV exposure for 1 hour.

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

    International Nuclear Information System (INIS)

    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)

  13. Influence of high-energy electron beam on photo catalytic activity of TiO2 films on carbon-fiber deposited by atomic layer deposition

    International Nuclear Information System (INIS)

    High energy electron-beam with energy of 1 MeV was used for modifying surface structure of TiO2 thin films on carbon fiber prepared by using atomic layer deposition under atmospheric pressure. TiO2 nanoparticles on carbon fiber underwent structural modification of the surface upon electron-beam treatment, resulting in enhanced photo catalytic activity. In contrast, a thicker film of TiO2 did not show such changes in surface structure and photo catalytic activity by electron-beam treatment. We demonstrate that electron-beam can be used for modifying surface structure of photo catalysts consisting of nanoparticles for improvement of their activity

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

    Science.gov (United States)

    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

  15. PHOTOCATALYTIC TIO2 FILMS AND MEMBRANES FOR THE DEVELOPMENT OF EFFICIENT WASTEWATER TREATMENT AND REUSE SYSTEMS

    Science.gov (United States)

    In order to develop efficient photocatalytic TiO2 films and membranes for application in water and wastewater treatment and reuse systems, there is a great need to tailor-design the structural properties of TiO2 material and enhance its photocatalytic activity. Through...

  16. Antibacterial activity of DLC films containing TiO2 nanoparticles.

    Science.gov (United States)

    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

  17. Effect of chemisorbed surface species on the photocatalytic activity of TiO2 nanoparticulate films

    International Nuclear Information System (INIS)

    TiO2 sols prepared in acidic and basic medium were deposited into films by a spin coating method. Photodegradation experiments showed that photocatalytic activity of the films prepared from acidic sol was much higher than that from basic sol. It is identified that there are more chemisorbed species of CO2 on the surface of the TiO2 films from the basic sol than on the surface of the TiO2 films from the acidic sol. The chemisorbed species of CO2 reduce the concentration of active species such as hydroxyl group and bridging oxygen on surface of the TiO2 film and contribute to the formation of surface electron traps in the band gap which are detrimental to charge separation, thus lowering the photocatalytic activity

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

    International Nuclear Information System (INIS)

    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.

  19. Photocatalytic Water Treatment on TiO2 Thin Layers.

    Czech Academy of Sciences Publication Activity Database

    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

  20. Preparation and characterization of polyvinyl alcohol films containing TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Polyvinyl alcohol films (PVA) doped with nanoparticles of TiO2 were prepared and characterized. These materials were obtained from a suspension of nanoparticles of TiO2 and PVA in 10% aqueous solution, and stabilized by ultrasound. The films of PVA-TiO2 (10, 100 and 1000 ppm of TiO2), of approximately 100μm of thickness, were prepared by pouring the mixture on glass plates and drying at room temperature by 48 h. These films were characterized by infrared spectroscopy (FT-IR) and UV-visible. No evidence of interaction between the chains of PVA and TiO2 was found. The dispersion of the TiO2 in the polymeric matrix was evaluated using the scanning electron microscopy (SEM). In spite of the treatment by ultrasound, the films show TiO2 agglomerates of different sizes. These films have better mechanical properties. It was observed an increase of the Young modulus as a function of the TiO2 concentration. Simultaneously the elongation of breakage diminishes. Nevertheless, significant changes in the tensile strength were not observed. (author)

  1. TiO2 anatase films obtained by direct liquid injection atomic layer deposition at low temperature

    Science.gov (United States)

    Avril, L.; Reymond-Laruinaz, S.; Decams, J. M.; Bruyère, S.; Potin, V.; de Lucas, M. C. Marco; Imhoff, L.

    2014-01-01

    TiO2 thin films were grown by direct liquid injection atomic layer deposition (DLI-ALD) with infrared rapid thermal heating using titanium tetraisopropoxide and water as precursors. This titanium tetraisopropoxide/water process exhibited a growth rate of 0.018 nm/cycle in a self-limited ALD growth mode at 280 °C. Scanning electron microscopy and atomic force microscopy analyses have shown a smooth surface with a low roughness. XPS results demonstrated that the films were pure and close to the TiO2 stoichiometric composition in depth. Raman spectroscopy revealed that the films were crystallized to the anatase structure in the as-deposited state at low temperature without necessity of high temperature annealing. Results obtained demonstrate that the liquid injection ALD is an efficient method of elaborating titanium oxide films using titanium tetraisopropoxide as precursor.

  2. Impact of Thickness of Columnar Crystal TiO2 Film on Photocatalytic Activity of FTO/TiO2 Coated Glass

    Directory of Open Access Journals (Sweden)

    TENG Fan, LIU Yong, GE Yan-Kai, ZHANG Rui-Shuo, SONG Chen-Lu, HAN Gao-Rong

    2012-06-01

    Full Text Available Columnar crystal structured TiO2 thin films were prepared on the FTO (SnO2: F) low―emissivity coated glass substrates, obtaining double―layer structure FTO/TiO2 coated glass samples. The effect of TiO2 film thickness on the photocatalytic activity, the low―emissivity performance and light transmission properties of the FTO/TiO2 coated glass samples was investigated. The results showed that the photocatalytic activity of the samples increased firstly and then decrease with the increase of the film thickness. The best catalytic activity was observed for the sample coated with 300 nm TiO2 film. The low―emissivity properties of the samples declined as the TiO2 film thickness increased. The sample still have some low―emissivity performance when the TiO2 film thickness is 300 nm, while the light transmittance of the samples have little relations with the TiO2 films thickness. The visible light transmittances of the samples remain at about 72% with a smooth surface. The average surface roughness of the sample is about 1 nm. The FTO/TiO2 coated glass has photocatalytic self―cleaning properties with excellent low emissive performance and light transmittance property, thus guaranteeing good application prospects.

  3. Low crystallinity TiO2 film with inherent low oxygen vacancy for sensitized solar cells

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: The low crystallinity TiO2 film is with inherent low content of oxygen vacancies. The low crystallinity TiO2 possesses Deff and ?eff one time higher than nanocrystalline TiO2 does. The extraordinary high open photovoltage of 860 mV is achieved. Internal electron loss of the cell based on the low crystallinity TiO2 film is quite low. - Abstract: Instead of perfect crystallization or surface defect-removing treatments, this study suggests an alternative route of oxygen vacancy reduction, i.e. amorphization, to improve the electron transport properties of TiO2 mesoporous films. In this paper, a low crystallinity TiO2 mesoporous film with inherent low content of oxygen vacancies is used as the photoanode of dye-sensitized solar cells (DSCs). Electrochemical impedance spectroscopy (EIS) analysis indicates the high electron diffusion coefficient and long electron life time of the low crystallinity TiO2 photoanode. An extraordinary high open photovoltage of 860 mV is achieved owing to the low oxygen vacancy. And also the charge recombination of the internal cell significantly decreases, thus enhances the utilization efficiency of dye, which has been characterized with the high ratio of short circuit photocurrent to dye-loading

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Indian Academy of Sciences (India)

    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.

  6. Effects of Morphology of Anatase TiO2 Nanotube Films on Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    CUI Qiang, FENG Bo, CHEN Wei, WANG Jian-Xin, LU Xiong, WENG Jie

    2010-09-01

    Full Text Available Five groups of TiO2 nanotube array films with different inner diameters and five groups with different tube lengths were fabricated on titanium by anodization. Morphology was analyzed by scanning electron microscope. The photocatalytic activity of the TiO2 nanotube films crystallized into anatase, was evaluated by the decolorization of methyl orange in aqueous solution under UV light irradiation. The effects of the nanotube diameter and length on the photocatalytic activity were investigated. The reusability of photocatalyst was evaluated through repeated photocatalytic reaction experiment. Results suggest that the TiO2 nanotube films with the diameter of 100nm exhibit the best photocatalytic activity to the degradation of methyl orange, and the length of nanotube has little effect on the photocatalytic activity. Repeated photocatalytic reaction experiment shows that the TiO2 nanotube films have excellent resuability as photocatalyst.

  7. Optical properties of sputter deposited transparent and conducting TiO2:Nb films

    International Nuclear Information System (INIS)

    Transparent and conducting thin films of TiO2:Nb were prepared on glass by reactive dc magnetron sputtering in Ar + O2. Post-deposition annealing in vacuum at 450 oC led to good electrical conductivity and optical transparency. The optical properties in the sub-bandgap region were in good agreement with Drude free electron theory, which accounts for intraband absorption. The band gap of the films was found to be in the range of 3.3 to 3.5 eV and signifies the onset of interband absorption. Electrical conductivities in the 10-3 Ω cm range were obtained both from dc electrical measurements and from analysis of the optical measurements.

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

    International Nuclear Information System (INIS)

    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

  9. Investigations on TIO2 and AG based single and multilayer films for window glazings

    OpenAIRE

    M.M.Hasan; A. B. M. Malek; A.S.M.A. Haseeb; H.H. Masjuki

    2010-01-01

    In this investigation, TiO2 and Ag based single and multilayer-films were deposited on microscope glass slides with varying individual layer thicknesses by radio-frequency reactive magnetron sputtering. Prior to multilayer development, single layers of Ag and TiO2 were deposited and characterized. All the films were prepared at an elevated pressure of 3 Pa at room temperature. It was found that single layer of TiO2 showed anatase polycrystalline structure. It also exhibited high visible trans...

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

    International Nuclear Information System (INIS)

    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)

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

    International Nuclear Information System (INIS)

    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

  12. TiO2 nanofiber solid-state dye sensitized solar cells with thin TiO2 hole blocking layer prepared by atomic layer deposition

    International Nuclear Information System (INIS)

    We incorporated a thin but structurally dense TiO2 layer prepared by atomic layer deposition (ALD) as an efficient hole blocking layer in the TiO2 nanofiber based solid-state dye sensitized solar cell (ss-DSSC). The nanofiber ss-DSSCs having ALD TiO2 layers displayed increased open circuit voltage, short circuit current density, and power conversion efficiency compared to control devices with blocking layers prepared by spin-coating liquid TiO2 precursor. We attribute the improved photovoltaic device performance to the structural integrity of ALD-coated TiO2 layer and consequently enhanced hole blocking effect that results in reduced dark leakage current and increased charge carrier lifetime. - Highlights: • TiO2 blocking locking layer prepared by atomic layer deposition (ALD) method. • ALD-coated TiO2 layer enhanced hole blocking effect. • ALD blocking layer improved the voltage, current and efficiency. • ALD blocking layer reduced dark leakage current and increased electron lifetime

  13. Enhanced photoelectrocatalytic degradation of phenols with bifunctionalized dye-sensitized TiO2 film

    International Nuclear Information System (INIS)

    Highlights: ► Bifunctionalized TiO2 film with a dye-sensitized region and a degradation region. ► Electrons and positive charges induced by visible light participate in degradation. ► The degradation efficiency is enhanced remarkably by external potential. ► 99% removal of 4-chlorophenol was achieved by this device after 2 h. - Abstract: A degradation device containing a bifunctionalized TiO2 film electrode and an anode electrode was described. The bifunctionalized TiO2 film electrode is composite of an area of dye-sensitized TiO2 film, electrolyte and counter electrode, which is similar to the structure of dye-sensitized solar cells (DSSCs). Electrons and positive charges induced by visible light absorption of dyes could arrive at the degradation region of the bifunctionalized TiO2 film electrode and the anode electrode, respectively. Both could produce hydroxyl radicals (·OH) to participate in the degradation reaction. The degradation efficiency was enhanced remarkably by an external potential. Meanwhile, the effects of dye-sensitized TiO2 film area and pH value on the degradation of 4-chlorophenol (4-CP) were tested. An insight into degradation pathway, plausible mechanism for 4-CP and degradation of other phenols were also discussed here.

  14. Photo-oxidative degradation of TiO2/polypropylene films

    International Nuclear Information System (INIS)

    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)

  15. Effect of compressive stress inducing a band gap narrowing on the photoinduced activities of solgel TiO2 films

    International Nuclear Information System (INIS)

    TiO2 thin films grown on different kinds of substrates were obtained by solgel 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). UVVis absorbance spectra exhibited a red-shift of the absorbance edge of the TiO2 films suggesting a lowering of the band gap, which is a direct consequence of the increase of the compressive stress. X-ray photoelectron spectroscopy revealed that the surface composition of titania films was similar except for sodium-ion concentration. The rate observed during the photo-oxydation of the stearic acid on TiO2/QS was twice as high as that of TiO2/BSG and about 1000 times superior to that of TiO2/SLG. The photoinduced wettability shows an identical dependence of the compressive stress. According to these results, the compressive stress could be used to tune the band gap of the titanium oxide in order to enhance the photoinduced properties.

  16. Passivation of TiO2 by ultra-thin Al-oxide

    International Nuclear Information System (INIS)

    The passivation of sol-gel TiO2 by ultra-thin layers of Al-oxide has been investigated using transient and spectral photovoltage (PV) techniques. The ultra-thin layers of Al-oxide were prepared by the ion-layer gas reaction (ILGAR) technique and modified by thermal treatments in air, vacuum or Ar/H2S atmosphere. The samples where characterized by elastic recoil detection analysis (ERDA), X-ray photoelectron spectroscopy (XPS), and contact potential difference (CPD) technique. Without an Al-oxide surface layer, electronic states in the forbidden gap of TiO2 are formed during thermal treatments in vacuum and Ar/H2S. The trap density is strongly reduced at the TiO2/Al-oxide interface. The formation of electronic defects is prevented by a closed ultra-thin layer of Al-oxide

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

    Directory of Open Access Journals (Sweden)

    2009-03-01

    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.

  18. Anatase TiO2 Films Crystallized by RF Plasma Treatment

    International Nuclear Information System (INIS)

    Anatase-phase TiO2 films were prepared from amorphous TiO2 films with using a novel crystallization technology in which 13.56 MHz rf (radio frequency) plasma is applied to the film samples for few minutes without heating. The obtained anatase TiO2 films have almost the same photocatalytic degradation activity as that of the thermally-crystallized anatase TiO2 films. Although the key parameter of this plasma crystallization process is the plasma gas pressure, the best plasma gas pressure depends on the plasma gas species and applied rf power and is independent to film materials nor substrate materials. Experimental results strongly suggest that the plasma crystallization is realized by the application of alternating rf electric field into the film materials. Easiness of plasma crystallization of TiO2 films is found to depend on the film preparation conditions and this relation between crystallization easiness and preparation condition is different from the relation in the heat crystallization.

  19. Graphene incorporated nanocrystalline TiO2 films for the photocathodic protection of 304 stainless steel

    International Nuclear Information System (INIS)

    Composite films of TiO2 and graphene (GR) were prepared on 304 stainless steel (304SS) by the solgel method and heat treatment. The morphology, crystalline phase, and composition of the GR/TiO2 films were characterized systematically by X-ray diffraction, Raman spectroscopy and scanning electron microscopy, respectively. The photocathodic protection performances of the composite film under illumination and dark conditions in 3.0% NaCl solution were evaluated through the electrochemical measurements. It is indicated that the incorporation of GR in TiO2 film can improve effectively the photocathodic protection effect for 304SS under the UV illumination. Compared to 350 mV of pure TiO2 film, the electrode potentials can be negatively shifted to about ?600 mV under UV light irradiation by incorporating GR into TiO2 films. At the same time, a 14-fold photocurrent density can be obtained for the GR/TiO2 film. This indicates that GR can play an excellent enhancing effect on the photogenerated cathodic protection of TiO2 films.

  20. Fabrication of Nb-Doped TiO2 Transparent Conducting Films by Postdeposition Annealing under Nitrogen Atmosphere

    Science.gov (United States)

    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.

  1. Optimization of the structure nanoporous TiO2 film in a dye- sensitized solar cell

    International Nuclear Information System (INIS)

    The numerical model of dye-sensitized solar cell based on TiO2 presented here allow to construct the theoretical I-V characteristics, determine the photovoltaic parameters and obtain important information about the main factors that influence DSSC performance. For modeling of solar cell was considered system of one-dimensional differential continuity equations, describing the charge transfer in its structure. The simulated results allow to determine the optimal TiO2 particle diameter (radius), thickness, porosity and topological dimensions TiO2 film

  2. Synthesis of polycarbonate-r-polyethylene glycol copolymer for templated synthesis of mesoporous TiO2 films.

    Science.gov (United States)

    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

  3. Electrochromic multilayer films with enhanced stability based on polyoxometalate and TiO2

    International Nuclear Information System (INIS)

    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.

  4. Interface feature characterization and Schottky interfacial layer confirmation of TiO2 nanotube array film

    Science.gov (United States)

    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.

  5. Optical Study of Ultrathin TiO2 Films for Photovoltaic and Gas Sensing Applications

    Directory of Open Access Journals (Sweden)

    Arturas SUCHODOLSKIS

    2014-06-01

    Full Text Available TiO2 ultrathin films of thickness below 20 nm were deposited by reactive RF magnetron sputtering. The optical properties of TiO2 films were investigated by various optical techniques including UV-VIS-NIR spectroscopic ellipsometry. The Scanning Probe Microscopy (SPM was used to determine thickness and surface roughness of the deposited films. The correlation between preparation conditions of ultrathin TiO2 films and their physical properties has been studied. The analysis of optical data revealed the parameters of deposited films and intrinsic properties of TiO2 material before and after annealing. We found that deposited layers were predominantly amorphous with high porosity at the top sample, and absence of porosity at the bottom of TiO2 layer. Annealing considerably improves structural order of the studied samples and the film transforms to the polycrystalline anatase phase. Also we evaluated the energy bandgap (about 3.1 eV – 3.2 eV which increases after annealing (above 3.3 eV and it is  close to the bandgap of anatase. DOI: http://dx.doi.org/10.5755/j01.ms.20.2.6328

  6. Optical properties of TiO2 film after annealing in nitrogen

    International Nuclear Information System (INIS)

    In order to prepare nitrogen-doped TiO2 film in the surface of SiO2 glass, Ti ion implantation was performed at room temperature in fused silica and then the as-implanted samples were annealed in nitrogen ambient up to 900 degree C. SRIM code and Rutherford backscattering spectrometry(RBS) showed a Gauss distribution of Ti ions in the surface of as-implanted samples. The experimental profile of Ti ions is consistent with the simulated one. X-ray photoelectron spectroscopy(XPS) indicated that metallic Ti and TiO2 coexisted in the as-implanted samples. After annealing at 900 degree C, metallic Ti was oxidized into TiO2, and a new compound of O-Ti-N formed because a small amount of oxygen atoms were substituted by nitrogen atoms in the lattice of TiO2. UV-Vis spectra indicated that the optical absorption edge of TiO2 appeared after annealing at 500 degree C. After annealing at 900 degree C, red shift of the optical absorption edge of TiO2 was observed from 3.98 eV (500 degree C) to 3.30 eV due to the formation of O-Ti-N compound. The tail of the absorption edge extended to the visible waveband and the absorbance of TiO2 increased in the visible waveband. (authors)

  7. Effect of H2 Exposure on TiO2-based Ceramic Thick Films

    Directory of Open Access Journals (Sweden)

    Frade, J. R.

    1999-12-01

    Full Text Available Thick-film sensors based on TiO2 (anatase and rutile and composites of TiO2-Al2O3 and TiO2-Y2O3 have been tested for their electrical response on exposure to H2. Film d.c. resistance was measured in the temperature range 500-650C as a function of time and gas-phase composition (air, N2 and 10% H2 in an N2-based stream; the equilibrium gas-phase Po2 was simultaneously monitored with a ZrO2-based oxygen sensor. The detection mechanism of TiO2 to H2 involves the formation of fully ionised oxygen vacancies for both anatase and rutile. The addition of Al2O3 and Y2O3 did little to affect film sensitivity at the tested H2 concentration levels.Los sensores de lmina gruesa basados en TIO2 (Anatasa y rutilo y materiales compuestos de TiO2-Al203 y TiO2-Y2O3 han sido evaluados en funcin de su respuesta elctrica a la exposicin de H2. La resistencia d.c. de las lminas fue medida en el rango de temperaturas de 500-560C en funcin del tiempo y la composicin de la fase gaseosa (aire, N2 y 10% H2 en un vapor basado en N2; el equilibrio de P02 de la fase gaseosa fue simultneamente monitorizado con un sensor de oxgeno basado en ZrO2. El mecanismo de deteccin del H2 por el TiO2 incluye la formacin de vacantes de oxgeno totalmente ionizadas por la anatasa y el rutilo. La adicin de Al2O3 y Y2O3 apenas afecta la sensibilidad de la lmina en los niveles de H2 evaluados.

  8. Phase-controlled preparation of TiO2 films and micro(nano)spheres by low-temperature chemical bath deposition

    International Nuclear Information System (INIS)

    Highlights: •Simultaneously preparation of TiO2 films and sphere-like precipitates by low-temperature chemical bath deposition. •The same building blocks observed in the films and precipitates. •Cluster-by-cluster attachment is succeeded by the ion-by-ion growth. •Phase-controlled growth of TiO2 by the effects of solvent or fluorine ion. -- Abstract: TiO2 films and micro(nano)spheres have been simultaneously prepared by means of low-temperature chemical bath deposition (CBD). The films and precipitates are found to be constructed of the same building blocks regardless of the bath conditions. Thin nanosheets of ca. 20 nm in thickness serve as the building blocks of rutile TiO2 grown in an acidic bath. They aggregate to form spheres to reduce the surface energy of the precipitates, while in the films they grow into discrete crystallites on the seeded substrate. Fine control over the crystalline phase of TiO2 is achieved by replacing some water with ethanol or the addition of NH4F. A gradual transition from rutile to anatase is observed as the ethanol and NH4F contents are increased. Moreover, the crystallite size of TiO2 is significantly reduced and there exists monodisperse nanoparticles and aggregate microspheres in the products modified with ethanol and NH4F, respectively. This size-dependent phase transition is consistent with previous theoretical and thermodynamic studies. The facile tune of the TiO2 phase by low-temperature CBD method may be useful to improve the performance of TiO2 for its various applications

  9. Polyvinyl pyrrolidone aided preparation of TiO2 films used in flexible dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Highlights: · Polyvinyl pyrrolidone (PVP) is used to low temperature prepare TiO2 film in flexible DSSC. · PVP improves TiO2 dispersion, adherence to flexible substrate and dye adsorption. · Ultraviolet light irradiation improve the surface state of TiO2 film. · Resultant flexible DSSC achieves a light-to-electric conversion efficiency of 3.02%. - Abstract: Polyvinyl pyrrolidone (PVP) is introduced to low temperature preparation of a good quality TiO2 film used in flexible dye-sensitized solar cells (DSSCs). The samples are characterized by scanning electron microscopy and UV-vis absorption spectra, the photovoltaic performance of the DSSC is measured. It is found that PVP can improve the dispersion of TiO2 particles and the adherence of TiO2 particles to flexible substrate, as well as the adsorption of sensitized dye to TiO2 film. Additionally, ultraviolet light irradiation can eliminate organics remained on the surface the TiO2 film and improve the surface state of TiO2 film. Under an optimal condition, a flexible DSSC using TiO2 film doped PVP and UV irradiation treated achieves a light-to-electric energy conversion efficiency of 3.02% under irradiation with a simulate solar light intensity of 100 mW cm-2.

  10. Dye-Sensitized Nanostructured TiO2 Film Based Photoconductor

    CERN Document Server

    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.

  11. TiO2 Sub-microsphere Film as Scaffold Layer for Efficient Perovskite Solar Cells.

    Science.gov (United States)

    Huang, Yang; Zhu, Jun; Ding, Yong; Chen, Shuanghong; Zhang, Changneng; Dai, Songyuan

    2016-03-30

    TiO2 sub-microspheres composed of anatase granular-like nanocrystallines with an average diameter ∼250 nm are synthesized using sol-gel method and employed as the scaffold layer for efficient mesocopic perovskite solar cells. Compared with mesoporous TiO2 films composed of ∼18 nm nanoparticles, the sub-microsphere films show superior light-trapping characteristics and significantly improve the light-harvesting capability of the solar cells. In addition, the charge-transport performance is also dramatically improved according to the transient photocurrent decay despite there being no significant difference in the perovskite layer surface morphology. As a result, an average power conversion efficiency of 15% with a highly uniform distribution is achieved for the solar cells with TiO2 sub-microsphere films, 12% higher than those with TiO2 nanoparticle films. The combination of light-harvesting capability and fast charge transfer make the TiO2 sub-microsphere film a good candidate as the scaffold layer for efficient perovskite solar cells. PMID:26953635

  12. Low-temperature atomic layer deposition of TiO2 thin layers for the processing of memristive devices

    International Nuclear Information System (INIS)

    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

  13. Preparation and surface wettability of TiO2 nanorod films modified with triethoxyoctylsilane

    International Nuclear Information System (INIS)

    Nanostructured TiO2 arrays were prepared through a facile and environmentally friendly hydrothermal method on fluorine-doped tin oxide coated glass substrates with tunable surface morphologies without using any catalysts, seeds or templates. Their crystal structure, surface morphology, compositions and wettability were investigated by X-ray diffraction, field emission scanning electron microscope, X-ray photoelectron spectroscope and contact angle measurements, respectively. It is found that the concentration of hydrochloric acid has a great influence on the morphology and wettability of TiO2 nanorod films. Typically, the film prepared with 7.0 M HCl exhibits a high water contact angle of 157.3 ± 1.5° with an advancing contact angle of 154.2 ± 1.3° and a receding contact angle of 161.2 ± 1.3° and a small sliding angle of 7° after hydrophobic treatment. The Cassie theory was used to analyze the hydrophobic phenomenon of the as-prepared film, and it reveals that only about 9% of the water surface is contacted with the TiO2 film and the remaining 91% is contacted with the air cushion, which is reasonable for the hydrophobicity of a TiO2 nanorod film. - Highlights: ► Well-aligned TiO2 nanorod films were prepared. ► The effect of HCl concentration on the wettability of TiO2 films was analyzed. ► Superhydrophobic surface was achieved by modifying films with triethoxyoctylsilane. ► The water contact angle of 157.3 ± 1.5° has been achieved

  14. The influence of metal interlayers on the structural and optical properties of nano-crystalline TiO 2 films

    KAUST Repository

    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.

  15. Inkjet printed highly porous TiO2 films for improved electrical properties of photoanode.

    Science.gov (United States)

    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

  16. Synthesis of TiO2-doped SiO2 composite films and its applications

    Indian Academy of Sciences (India)

    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.

  17. Sol-gel TiO2 films as NO2 gas sensors

    International Nuclear Information System (INIS)

    TiO2 films were prepared by a sol-gel technique with commercial TiO2 powder as a source material (P25 Degussa AG). After a special treatment, printing paste was prepared. The TiO2 layers were formed by means of drop-coating on Si-control wafers and on the Au-electrodes of quartz resonators. The surface morphology of the films was examined by scanning electron microscopy (SEM). Their structure was studied by Raman spectroscopy and the surface composition was determined by X-ray photoelectron spectroscopy (XPS). The layers had a grain-like surface morphology and consisted mainly of anatase TiO2 phase. The sensitivity of the TiO2 films to NO2 was assessed by the quartz crystal microbalance (QCM) technique. To this end, the films were deposited on both sides of a 16-MHz QCM. The sensing characteristic of the TiO2-QCM structure was investigated by measuring the resonant frequency shift (ΔF) of the QCM due to the mass loading caused by NO2 adsorption. The Sauerbrey equation was applied to establish the correlation between the QCM frequency changes measured after exposure to different NO2 concentrations and the mass-loading of the QCM. The experiments were carried out in a dynamic mode on a special laboratory setup with complete control of the process parameters. The TiO2 films were tested in the NO2 concentration interval from 10 ppm to 5000 ppm. It was found that a TiO2 loading of the QCM by 5.76 kHz corresponded to a system sensitive to NO2 concentrations above 250 ppm. On the basis of the frequency-time characteristics (FTCs) measured, AF at different NO2 concentrations was defined, the adsorption/desorption cycles were studied and the response and recovery times were estimated. The results obtained show that the process is reversible in the NO2 interval investigated. The results further suggested that TiO2 films prepared by a sol-gel method on a QCM can be used as a sensor element for NO2 detection.

  18. Effect of substrate type, dopant and thermal treatment on physicochemical properties of TiO2–SnO2 sol–gel films

    Indian Academy of Sciences (India)

    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).

  19. Preparation of TiO2/boron-doped diamond/Ta multilayer films and use as electrode materials for supercapacitors

    Science.gov (United States)

    Shi, Chao; Li, Hongji; Li, Cuiping; Li, Mingji; Qu, Changqing; Yang, Baohe

    2015-12-01

    We report nanostructured TiO2/boron-doped diamond (BDD)/Ta multilayer films and their electrochemical performances as supercapacitor electrodes. The BDD films were grown on Ta substrates using electron-assisted hot filament chemical vapor deposition. Ti metal layers were deposited on the BDD surfaces by radio frequency magnetron sputtering, and nanostructured TiO2/BDD/Ta thin films were prepared by electrochemical etching and thermal annealing. The successful formation of TiO2 and Ta layered nanostructures was demonstrated using scanning electron and transmission electron microscopies. The electrochemical responses of these electrodes were evaluated by examining their use as electrical double-layer capacitors, using cyclic voltammetry, and galvanostatic charge/discharge and impedance measurements. When the TiO2/BDD/Ta film was used as the working electrode with 0.1 M Na2SO4 as the electrolyte, the capacitor had a specific capacitance of 5.23 mF cm-2 at a scan rate of 5 mV s-1 for a B/C ratio of 0.1% w/w. Furthermore, the TiO2/BDD/Ta film had improved electrochemical stability, with a retention of 89.3% after 500 cycles. This electrochemical behavior is attributed to the quality of the BDD, the surface roughness and electrocatalytic activities of the TiO2 layer and Ta nanoporous structures, and the synergies between them. These results show that TiO2/BDD/Ta films are promising as capacitor electrodes for special applications.

  20. Incorporation of N in TiO2 films grown by DC-reactive magnetron sputtering

    International Nuclear Information System (INIS)

    Photocatalytic properties of TiO2 are expected to play an important role on emerging technologies based on OH radicals to destroy harmful nonbiodegradable organic and inorganic contaminants in water. The drawback is the wide band gap of TiO2 (3.2 eV) limiting its use to the UV part of electromagnetic spectrum under sunlight. Therefore, modifications of TiO2 are needed to tune the gap in order to allow an efficient use of the entire solar spectrum. One possibility is N-doping of TiO2 to make the photocatalytic activity possible under visible light and more suitable for water treatment. In our study nitrogen-doped TiO2 (TiO2−xNx) films were deposited by DC-reactive magnetron sputtering using a dual-magnetron co-deposition apparatus on unheated glass and silicon substrates using a pure titanium target. The depth profile of nitrogen was measured with heavy ion elastic recoil detection analysis combined with Rutherford backscattering spectrometry (RBS) and correlated with the optical and structural properties obtained by UV–VIS spectroscopy and X-ray diffraction (XRD).