TiO2-BASED Composite Films for the Photodegradation of Oxytetracycline

Science.gov (United States)

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

2015-02-01

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

Synthesis and characterization of Fe3+ doped TiO2 nanoparticles and films and their performance for photocurrent response under UV illumination

International Nuclear Information System (INIS)

Elghniji, Kais; Atyaoui, Atef; Livraghi, Stefano; Bousselmi, Latifa; Giamello, Elio; Ksibi, Mohamed

2012-01-01

Graphical abstract: Schematic diagram illustrating the charge transfer from excited TiO 2 to the different states of Fe 3+ ions; C B and V B refer to the energy levels of the conduction and valence bands of TiO 2 , respectively. Highlights: ► In this study we examine the Iron as catalyst precursor to synthesize the Fe 3+ doped TiO 2 nanoparticles. ► The Fe 3+ doped TiO 2 catalysts show the presence of a mixed phase of anatase. ► The iron is completely absent in the XRD pattern of the doped iron TiO 2 powder. ► The analysis of EPR result further confirms that Fe 3+ ion are successfully doped in the TiO 2 lattice by substituting Ti 4+ . ► Fe 3+ doping can efficiently separate the photo-generated electrons and holes. - Abstract: Undoped TiO 2 and Fe 3+ doped (0.1, 0.3, 0.6 and 1 wt.%) TiO 2 nanoparticles have been synthesized by the acid-catalyzed sol–gel method. Iron cations are introduced in the initial solution, before gelification, what promotes their lattice localization. The Fe 3+ doped TiO 2 films have been fabricated using a dip-coating technique. The effect of iron content on the crystalline structure, phase transformation and grain growth were determined by X-ray diffraction (XRD), Raman spectroscopy, UV–visible diffused reflectance spectroscopy (DRS) and Electron paramagnetic resonance (EPR) spectroscopy. It has demonstrated that all catalysts are composed of mixed-phase crystals of anatase and brookite with anatase as dominant phase. The crystallinity of the brookite and anatase phases decreased with increasing the iron content. The analysis of EPR result further confirms that Fe 3+ ion are successfully doped in the TiO 2 lattice by substituting Ti 4+ . It was demonstrated that Fe 3+ ion in the TiO 2 films plays a role as the intermediate for the efficient separation of photogenerated hole–electron pairs and increases the photocurrent response of the film under UV light irradiation. The maximum photocurrent is obtained on the Fe 3+ doped TiO

Effect of iron doping on structural and optical properties of TiO2 thin film by sol–gel routed spin coating technique

Directory of Open Access Journals (Sweden)

Stephen Lourduraj

2017-08-01

Full Text Available Thin films of iron (Fe-doped titanium dioxide (Fe:TiO2 were prepared by sol–gel spin coating technique and further calcined at 450∘C. The structural and optical properties of Fe-doped TiO2 thin films were investigated by X-ray diffraction (XRD, scanning electron microscopy (SEM, ultraviolet–visible spectroscopy (UV–vis and atomic force microscopic (AFM techniques. The XRD results confirm the nanostructured TiO2 thin films having crystalline nature with anatase phase. The characterization results show that the calcined thin films having high crystallinity and the effect of iron substitution lead to decreased crystallinity. The SEM investigations of Fe-doped TiO2 films also gave evidence that the films were continuous spherical shaped particles with a nanometric range of grain size and film was porous in nature. AFM analysis establishes that the uniformity of the TiO2 thin film with average roughness values. The optical measurements show that the films having high transparency in the visible region and the optical band gap energy of Fe-doped TiO2 film with iron (Fe decrease with increase in iron content. These important requirements for the Fe:TiO2 films are to be used as window layers in solar cells.

TiO2 and Cu/TiO2 Thin Films Prepared by SPT

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S. S. Roy

2015-12-01

Full Text Available Titanium oxide (TiO2 and copper (Cu doped titanium oxide (Cu/TiO2 thin films have been prepared by spray pyrolysis technique. Titanium chloride (TiCl4 and copper acetate (Cu(CH3COO2.H2O were used as source of Ti and Cu. The doping concentration of Cu was varied from 1-10 wt. %. The X-ray diffraction studies show that TiO2 thin films are tetragonal structure and Cu/TiO2 thin films implies CuO has present with monoclinic structure. The optical properties of the TiO2 thin films have been investigated as a function of Cu-doping level. The optical transmission of the thin films was found to increase from 88 % to 94 % with the addition of Cu up to 8 % and then decreases for higher percentage of Cu doping. The optical band gap (Eg for pure TiO2 thin film is found to be 3.40 eV. Due to Cu doping, the band gap is shifted to lower energies and then increases further with increasing the concentration of Cu. The refractive index of the TiO2 thin films is found to be 2.58 and the variation of refractive index is observed due to Cu doped. The room temperature resistivity of the films decreases with increasing Cu doping and is found to be 27.50 - 23.76 W·cm. It is evident from the present study that the Cu doping promoted the thin film morphology and thereby it is aspect for various applications.

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

International Nuclear Information System (INIS)

Barajas-Ledesma, E.; Garcia-Benjume, M.L.; Espitia-Cabrera, I.; Bravo-Patino, A.; Espinoza-Beltran, F.J.; Mostaghimi, J.; Contreras-Garcia, M.E.

2010-01-01

Al 2 O 3 -doped TiO 2 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 Al 2 O 3 -doped TiO 2 film-coated glass substrates were irradiated with visible light before they were introduced in the inoculum. The SEM and EDS results showed that TiO 2 -Al 2 O 3 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 TiO 2 was demonstrated. Al 2 O 3 -doped TiO 2 thin films were successful at eliminating E. coli.

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, and each chapter contains details which aim to develop awareness of the subject and the methods used. The content presented here will be useful for graduate students as well as researchers in materials science, physics, chemistry and engineering.

Phase transformations in sputter-deposited W-doped TiO2 films during annealing in air

International Nuclear Information System (INIS)

Saladukhin, I. A.; Abadias, G.

2013-01-01

Pure and tungsten-doped TiO 2 films are characterized as amorphous in the as-deposited state by XRD. A crystallization of titanium dioxide occurs during their annealing in air. Depending on the tungsten and nitrogen doping level, anatase or rutile phase formation is observed. Both of these phases are thermally stable in all interval of the temperatures used during annealing. Phase composition and lattice parameter analysis indicates on the formation of substitutional Ti 1 -xW x O 2 films. N-doped Ti 0 .75W 0 .25O 2 film is more resistant against high-temperature oxidation as compared to Ti 0 .74W 0 .26O 2 film and, especially, as compared to Ti 0 .60W 0 .40O 2 film. (authors)

High-Quality Fe-doped TiO2 films with Superior Visible-Light Performance

DEFF Research Database (Denmark)

Su, Ren; Bechstein, Ralf; Kibsgaard, Jakob

2012-01-01

We report on high-quality polycrystalline Fe-doped TiO2 (Fe–TiO2) porous films synthesized via one-step electrochemical oxidation. We demonstrate that delicate properties such as the impurity concentration and the microstructure that strongly influence the performance of the material for photovol...

A Humidity Sensor Based on Nb-doped Nanoporous TiO2 Thin Film

Directory of Open Access Journals (Sweden)

Mansoor Anbia

2011-11-01

Full Text Available The humidity sensing properties of the sensor fabricated from Nb-doped nanoporous TiO2 by screen-printing on the alumina substrate with Ag-Pd interdigital electrodes have been investigated. The nanoporous thin film has been prepared by sol-gel technique. The product has been characterized by X-ray diffraction and scanning electron microscopy to analyze the structure and its morphology. It is found that the impedance of this sensor changes more than four orders of magnitude in the relative humidity (RH range of 11–95 % at 25 °C. The response and recovery time of the sensor are about 19 and 25 s, respectively, during the RH variation from 11 to 95 %. The sensor shows high humidity sensitivity, rapid response and recovery, prominent stability, good repeatability and narrow hysteresis loop. These results indicate that Nb-doped nanoporous TiO2 thin films have a great potential for humidity sensing applications in room temperature operations.

Performance of Erbium-doped TiO2 thin film grown by physical vapor deposition technique

Science.gov (United States)

Lahiri, Rini; Ghosh, Anupam; Dwivedi, Shyam Murli Manohar Dhar; Chakrabartty, Shubhro; Chinnamuthu, P.; Mondal, Aniruddha

2017-09-01

Undoped and Erbium-doped TiO2 thin films (Er:TiO2 TFs) were fabricated on the n-type Si substrate using physical vapour deposition technique. Field emission scanning electron microscope showed the morphological change in the structure of Er:TiO2 TF as compared to undoped sample. Energy dispersive X-ray spectroscopy (EDX) confirmed the Er doping in the TiO2 thin film (TF). The XRD and Raman spectrum showed the presence of anatase phase TiO2 and Er2O3 in the Er:TiO2 TF. The Raman scattering depicted additional number of vibrational modes for Er:TiO2 TF due to the presence of Er as compared to the undoped TiO2 TF. The UV-Vis absorption measurement showed that Er:TiO2 TF had approximately 1.2 times more absorption over the undoped TiO2 TF in the range of 300-400 nm. The main band transition, i.e., the transition between the oxygen (2p) state and the Ti (3d) state was obtained at 3.0 eV for undoped TiO2 and at 3.2 eV for Er:TiO2 TF, respectively. The photo responsivity measurement was done on both the detectors, where Er:TiO2 TF detector showed better detectivity ( D *), noise equivalent power and temporal response as compared to undoped detector under ultra-violet illumination.

Structure and Properties of La2O3-TiO2 Nanocomposite Films for Biomedical Applications

Science.gov (United States)

Zhang, Lin; Sun, Zhi-Hua; Yu, Feng-Mei; Chen, Hong-Bin

2011-01-01

The hemocompatibility of La2O3-doped TiO2 films with different concentration prepared by radio frequency (RF) sputtering was studied. The microstructures and blood compatibility of TiO2 films were investigated by scan electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-visible optical absorption spectroscopy, respectively. With the increasing of the La2O3 concentrations, the TiO2 films become smooth, and the grain size becomes smaller. Meanwhile, the band gap of the samples increases from 2.85 to 3.3 eV with increasing of the La2O3 content in TiO2 films from 0 to 3.64%. La2O3-doped TiO2 films exhibit n-type semiconductor properties due to the existence of Ti2+ and Ti3+. The mechanism of hemocompatibility of TiO2 film doped with La2O3 was analyzed and discussed. PMID:22162671

Properties of Sn-doped TiO2 nanotubes fabricated by anodization of co-sputtered Ti–Sn thin films

International Nuclear Information System (INIS)

Kyeremateng, Nana Amponsah; Hornebecq, Virginie; Knauth, Philippe; Djenizian, Thierry

2012-01-01

Self-organized Sn-doped TiO 2 nanotubes (nts) were fabricated for the first time, by anodization of co-sputtered Ti and Sn thin films. This nanostructured material was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, UV–vis spectroscopy and transmission electron microscopy. Due to their remarkable properties, Sn-doped TiO 2 nts can find potential applications in Li-ion microbatteries, photovoltaics, and catalysis. Particularly, the electrochemical performance as an anode material for Li-ion microbatteries was evaluated in Li test cells. With current density of 70 μA cm −2 (1 C) and cut-off potential of 1 V, Sn-doped TiO 2 nts showed improved performance compared to simple TiO 2 nts, and differential capacity plots revealed that the material undergoes full electrochemical reaction as a Rutile-type TiO 2 .

Development of Dye-Sensitized Solar Cells with Sputtered N-Doped TiO2 Thin Films: From Modeling the Growth Mechanism of the Films to Fabrication of the Solar Cells

Directory of Open Access Journals (Sweden)

D. A. Duarte

2014-01-01

Full Text Available In this paper, nitrogen-doped TiO2 thin films were deposited by DC reactive sputtering at different doping levels for the development of dye-sensitized solar cells. The mechanism of film growth during the sputtering process and the effect of the nitrogen doping on the structural, optical, morphological, chemical, and electronic properties of the TiO2 were investigated by numerical modeling and experimental methods. The influence of the nitrogen doping on the working principle of the prototypes was investigated by current-voltage relations measured under illuminated and dark conditions. The results indicate that, during the film deposition, the control of the oxidation processes of the nitride layers plays a fundamental role for an effective incorporation of substitutional nitrogen in the film structure and cells built with nitrogen-doped TiO2 have higher short-circuit photocurrent in relation to that obtained with conventional DSSCs. On the other hand, DSSCs built with nondoped TiO2 have higher open-circuit voltage. These experimental observations indicate that the incorporation of nitrogen in the TiO2 lattice increases simultaneously the processes of generation and destruction of electric current.

Band-gap narrowing of TiO2 films induced by N-doping

International Nuclear Information System (INIS)

Nakano, Y.; Morikawa, T.; Ohwaki, T.; Taga, Y.

2006-01-01

N-doped TiO 2 films were deposited on n + -GaN/Al 2 O 3 substrates by reactive magnetron sputtering and subsequently crystallized by annealing at 550 o C in flowing N 2 gas. The N-doping concentration was ∼8.8%, as determined from X-ray photoelectron spectroscopy measurements. Deep-level optical spectroscopy measurements revealed two characteristic deep levels located at 1.18 and 2.48 eV below the conduction band. The 1.18 eV level is probably attributable to the O vacancy state and can be active as an efficient generation-recombination center. Additionally, the 2.48 eV band is newly introduced by the N-doping and contributes to band-gap narrowing by mixing with the O 2p valence band

Development of Dye-Sensitized Solar Cells with Sputtered N-Doped TiO2 Thin Films: From Modeling the Growth Mechanism of the Films to Fabrication of the Solar Cells

OpenAIRE

Duarte, D. A.; Massi, M.; da Silva Sobrinho, A. S.

2014-01-01

In this paper, nitrogen-doped TiO2 thin films were deposited by DC reactive sputtering at different doping levels for the development of dye-sensitized solar cells. The mechanism of film growth during the sputtering process and the effect of the nitrogen doping on the structural, optical, morphological, chemical, and electronic properties of the TiO2 were investigated by numerical modeling and experimental methods. The influence of the nitrogen doping on the working principle of the prototype...

Deep-level optical spectroscopy investigation of N-doped TiO2 films

International Nuclear Information System (INIS)

Nakano, Yoshitaka; Morikawa, Takeshi; Ohwaki, Takeshi; Taga, Yasunori

2005-01-01

N-doped TiO 2 films were deposited on n + -GaN/Al 2 O 3 substrates by reactive magnetron sputtering and subsequently crystallized by annealing at 550 deg. C in flowing N 2 gas. The N-doping concentration was ∼8.8%, as determined from x-ray photoelectron spectroscopy measurements. Deep-level optical spectroscopy measurements revealed two characteristic deep levels located at ∼1.18 and ∼2.48 eV below the conduction band. The 1.18 eV level is probably attributable to the O vacancy state and can be active as an efficient generation-recombination center. Additionally, the 2.48 eV band is newly introduced by the N doping and contributes to band-gap narrowing by mixing with the O 2p valence band

Electrochemically synthesized visible light absorbing vertically aligned N-doped TiO2 nanotube array films

International Nuclear Information System (INIS)

Antony, Rajini P.; Mathews, Tom; Ajikumar, P.K.; Krishna, D. Nandagopala; Dash, S.; Tyagi, A.K.

2012-01-01

Graphical abstract: Display Omitted Highlights: ► Single step electrochemical synthesis of N-doped TiO 2 nanotube array films. ► Effective substitutional N-doping achieved. ► Different N-concentrations were achieved by varying the N-precursor concentration in the electrolyte. ► Visible light absorption observed at high N-doping. -- Abstract: Visible light absorbing vertically aligned N-doped anatase nanotube array thin films were synthesized by anodizing Ti foils in ethylene glycol + NH 4 F + water mixture containing urea as nitrogen source. Different nitrogen concentrations were achieved by varying the urea content in the electrolyte. The structure, morphology, composition and optical band gap of the nanotube arrays were determined by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and diffuse reflectance spectroscopy, respectively. The substitution of O 2− ions by N 3− ions in the anion sublattice as well as the formulae of the doped samples was confirmed from the results of XPS. The optical band gap of the nanotube arrays was found to decrease with N-concentration. The sample with the highest concentration corresponding to the formula TiO 1.83 N 0.14 showed two regions in the Tauc's plot indicating the presence of interband states.

Synthesis, characterization and application of Co doped TiO2 multilayer thin films

Science.gov (United States)

Khan, M. I.

2018-06-01

To use the visible portion of solar light, 2% cobalt doped TiO2 (Co: TiO2) multilayer thin films having 1, 2, 3 and 4 stacked layers have been deposited on FTO substrates using spray pyrolysis technique. XRD results show that 1 and 2 layers of films have anatase phase. Brookite phase has been appeared at the 3 and 4 layered films. The average grain size of 1, 2, 3 and 4 layers of films are 14.4, 23.5, 29.7 and 33.6 nm respectively. UV-Vis results show that 4th layer film has high absorption in the visible region. The calculated Eg of 1, 2, 3 and 4 layers is 3.54, 3.42, 3.30 and 3.03 eV respectively. The calculated average sheet resistivity of 1, 2, 3 and 4 layers of films is 7.68 × 104, 4.54 × 104, 8.85 × 103 and 7.95 × 102 (ohm-m) respectively, according to four point probe technique. Solar simulator results show that highest solar conversion efficiency (5.6%) has been obtained by using 3 stacked layers photoanode. This new structure in the form of stack layers provides a way to improve the efficiency of optoelectronic devices.

Undoped TiO2 and nitrogen-doped TiO2 thin films deposited by atomic layer deposition on planar and architectured surfaces for photovoltaic applications

International Nuclear Information System (INIS)

Tian, Liang; Soum-Glaude, Adurey; Volpi, Fabien; Salvo, Luc; Berthomé, Grégory; Coindeau, Stéphane; Mantoux, Arnaud; Boichot, Raphaël; Lay, Sabine; Brizé, Virginie; Blanquet, Elisabeth; Giusti, Gaël; Bellet, Daniel

2015-01-01

Undoped and nitrogen doped TiO 2 thin films were deposited by atomic layer deposition on planar substrates. Deposition on 3D-architecture substrates made of metallic foams was also investigated to propose architectured photovoltaic stack fabrication. All the films were deposited at 265 °C and nitrogen incorporation was achieved by using titanium isopropoxide, NH 3 and/or N 2 O as precursors. The maximum nitrogen incorporation level obtained in this study was 2.9 at. %, resulting in films exhibiting a resistivity of 115 Ω cm (+/−10 Ω cm) combined with an average total transmittance of 60% in the 400–1000 nm wavelength range. Eventually, TiO 2 thin films were deposited on the 3D metallic foam template

Study of Sn and Mg doping effects on TiO2/Ge stack structure by combinatorial synthesis

Science.gov (United States)

Nagata, Takahiro; Suzuki, Yoshihisa; Yamashita, Yoshiyuki; Ogura, Atsushi; Chikyow, Toyohiro

2018-04-01

The effects of Sn and Mg doping of a TiO2 film on a Ge substrate were investigated to improve leakage current properties and Ge diffusion into the TiO2 film. For systematic analysis, dopant-composition-spread TiO2 samples with dopant concentrations of up to 20.0 at. % were fabricated by RF sputtering and a combinatorial method. X-ray photoelectron spectroscopy revealed that the instability of Mg doping of TiO2 at dopant concentrations above 10.5 at. %. Both Sn and Mg dopants reduced Ge diffusion into TiO2. Sn doping enhanced the crystallization of the rutile phase, which is a high-dielectric-constant phase, although the Mg-doped TiO2 film indicated an amorphous structure. Sn-doping indicated systematic leakage current reduction with increasing dopant concentration. Doping at Sn concentrations higher than 16.8 at. % improved the leakage properties (˜10-7 A/cm2 at -3.0 V) and capacitance-voltage properties of metal-insulator-semiconductor (MIS) operation. The Sn doping of TiO2 may be useful for interface control and as a dielectric material for Ge-based MIS capacitors.

Influence of Nd-Doping on Photocatalytic Properties of TiO2 Nanoparticles and Thin Film Coatings

Directory of Open Access Journals (Sweden)

Damian Wojcieszak

2014-01-01

Full Text Available Structural, optical, and photocatalytic properties of TiO2 and TiO2:Nd nanopowders and thin films composed of those materials have been compared. Titania nanoparticles with 1, 3, and 6 at. % of Nd-dopant were synthesized by sol-gel method. Additionally, thin films with the same material composition were prepared with the aid of spin-coating method. The analysis of structural investigations revealed that all as-prepared nanopowders were nanocrystalline and had TiO2-anatase structure. The average size of crystallites was ca. 4-5 nm and the correlation between the amount of neodymium and the size of TiO2 crystallites was observed. It was shown that the dopant content influenced the agglomeration of the nanoparticles. The results of photocatalytic decomposition of MO showed that doping with Nd (especially in the amount of 3 at. % increased self-cleaning activity of the prepared titania nanopowder. Similar effect was received in case of the thin films, but the decomposition rate was lower due to their smaller active surface area. However, the as-prepared TiO2:Nd photocatalyst in the form of thin films or nanopowders seems to be a very attractive material for various applications.

Formation of hydroxyl radicals and kinetic study of 2-chlorophenol photocatalytic oxidation using C-doped TiO2, N-doped TiO2, and C,N Co-doped TiO2 under visible light.

Science.gov (United States)

Ananpattarachai, Jirapat; Seraphin, Supapan; Kajitvichyanukul, Puangrat

2016-02-01

This work reports on synthesis, characterization, adsorption ability, formation rate of hydroxyl radicals (OH(•)), photocatalytic oxidation kinetics, and mineralization ability of C-doped titanium dioxide (TiO2), N-doped TiO2, and C,N co-doped TiO2 prepared by the sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy were used to analyze the titania. The rate of formation of OH(•) for each type of titania was determined, and the OH-index was calculated. The kinetics of as-synthesized TiO2 catalysts in photocatalytic oxidation of 2-chlorophenol (2-CP) under visible light irradiation were evaluated. Results revealed that nitrogen was incorporated into the lattice of titania with the structure of O-Ti-N linkages in N-doped TiO2 and C,N co-doped TiO2. Carbon was joined to the Ti-O-C bond in the C-doped TiO2 and C,N co-doped TiO2. The 2-CP adsorption ability of C,N co-doped TiO2 and C-doped TiO2 originated from a layer composed of a complex carbonaceous mixture at the surface of TiO2. C,N co-doped TiO2 had highest formation rate of OH(•) and photocatalytic activity due to a synergistic effect of carbon and nitrogen co-doping. The order of photocatalytic activity per unit surface area was the same as that of the formation rate of OH(•) unit surface area in the following order: C,N co-doped TiO2 > C-doped TiO2 > N-doped TiO2 > undoped TiO2.

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.

Photocatalytic properties of porous TiO2/Ag thin films

International Nuclear Information System (INIS)

Chang, C.-C.; Chen, J.-Y.; Hsu, T.-L.; Lin, C.-K.; Chan, C.-C.

2008-01-01

In this study, nanocrystalline TiO 2 /Ag composite thin films were prepared by a sol-gel spin-coating technique. By introducing polystyrene (PS) spheres into the precursor solution, porous TiO 2 /Ag thin films were prepared after calcination at a temperature of 500 deg. C for 4 h. Three different sizes (50, 200, and 400 nm) of PS spheres were used to prepare porous TiO 2 films. The as-prepared TiO 2 and TiO 2 /Ag thin films were characterized by X-ray diffractometry (XRD) and by scanning electron microscopy to reveal structural and morphological differences. In addition, the photocatalytic properties of these films were investigated by degrading methylene blue under UV irradiation. When PS spheres of different sizes were introduced after calcination, the as-prepared TiO 2 films exhibited different porous structures. XRD results showed that all TiO 2 /Ag films exhibited a major anatase phase. The photodegradation of porous TiO 2 thin films prepared with 200 nm PS spheres and doped with 1 mol% Ag exhibited the best photocatalytic efficiency where ∼ 100% methylene blue was decomposed within 8 h under UV exposure

Influence of Ni doping on phase transformation and optical properties of TiO2 films deposited on quartz substrates by sol-gel process

International Nuclear Information System (INIS)

Tian Jianjun; Deng Hongmei; Sun Lin; Kong Hui; Yang Pingxiong; Chu Junhao

2012-01-01

The Ni-doped TiO 2 films were synthesized on quartz substrates by the sol-gel method. Results from X-ray diffraction and Raman spectra indicate that Ni doping catalyzes the anatase-to-rutile transformation. When Ni content is up to 10 mol%, the transformation has been finished. The dielectric functions of Ni-doped TiO 2 films were extracted by fitting transmittance spectra according to the Adachi's dielectric function model. The optical band gap decreases from 3.64 eV to 3.51 eV with increasing Ni content. The results suggest that the acceleration of phase change and variation of optical properties may be related to defects due to Ni doping.

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)

Ben Naceur, J.; Mechiakh, R.; Bousbih, F.; Chtourou, R.

2011-01-01

Titanium dioxide (TiO 2 ) thin films doping of various iron ion (Fe 3+ ) 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 TiO 2 thin films comprised only the anatase TiO 2 , but the crystallinity decreased when the Fe 3+ content increased from 0% to 20%. During the Fe 3+ addition to 20%, the phase of TiO 2 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 (E g ) of the films were determined by the spectroscopic ellipsometry analysis. We have found that the optical band gap decreased with an increasing Fe 3+ content.

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

International Nuclear Information System (INIS)

Arpac, E.; Sayilkan, F.; Asiltuerk, M.; Tatar, P.; Kiraz, Nadir; Sayilkan, H.

2007-01-01

Sn-doped and undoped nano-TiO 2 particles have been synthesized by hydrotermal process without solvent at 200 deg. C in 1 h. Nanostructure-TiO 2 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-TiO 2 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 TiO 2 thin film

Anatase phase stability and doping concentration dependent refractivity in codoped transparent conducting TiO2 films

International Nuclear Information System (INIS)

Chen, T L; Furubayashi, Y; Hirose, Y; Hitosugi, T; Shimada, T; Hasegawa, T

2007-01-01

Nb 0.06 Sn x Ti 0.94-x O 2 (x ≤ 0.3) thin films were grown by a pulsed-laser deposition method with varying Sn concentration. Through a combinatorial technique, we find that Sn concentration can reach a maximum of about x = 0.3 while maintaining the stable anatase phase and epitaxy. A doping concentration dependence of the refractivity is revealed, in which refractivity reduction at a wavelength of λ = 500 nm is estimated to be 12.4% for Nb 0.06 Sn 0.3 Ti 0.64 O 2 thin film. Sn doping induced band-gap blue shift can be contributed to the mixing of extended Sn 5s orbitals with the conduction band of TiO 2 . Low resistivity on the order of 10 -4 Ω cm at room temperature and high internal transmittance of more than 95% in the visible light region are exhibited for Nb 0.06 Sn x Ti 0.94-x O 2 thin films (x ≤ 0.2). Optical and transport analyses demonstrate that doping Sn into Nb 0.06 Ti 0.94 O 2 can reduce the refractivity while maintaining low resistivity and high transparency

Photocatalytic properties of nanocrystalline TiO2 thin film with Ag additions

International Nuclear Information System (INIS)

Chang, C.-C.; Lin, C.-K.; Chan, C.-C.; Hsu, C.-S.; Chen, C.-Y.

2006-01-01

In the present study, nanocrystalline TiO 2 /Ag composite thin films were prepared by a sol-gel spin coating technique. While, by introducing polystyrene (PS) microspheres, porous TiO 2 /Ag films were obtained after calcining at a temperature of 500 o C. The as-prepared TiO 2 and TiO 2 /Ag thin 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 methylene blue under UV irradiation. After 500 o C calcination, the microstructure of PS-TiO 2 film without Ag addition exhibited a sponge-like microstructure while significant sintering effect was noticed with Ag additions and the films exhibited a porous microstructure. Meanwhile, coalescence of nanocrystalline anatase-phase TiO 2 can be observed with respect to the sharpening of XRD diffraction peaks. The photodegradation of porous TiO 2 doped with 1 mol% Ag exhibited the best photocatalytic efficiency where 72% methylene blue can be decomposed after UV exposure for 12 h

Characterization and Comparison of Photocatalytic Activity Silver Ion doped on TiO2(TiO2/Ag+) and Silver Ion doped on Black TiO2(Black TiO2/Ag+)

Science.gov (United States)

Kim, Jin Yi; Sim, Ho Hyung; Song, Sinae; Noh, Yeoung Ah; Lee, Hong Woon; Taik Kim, Hee

2018-03-01

Titanium dioxide (TiO2) is one of the representative ceramic materials containing photocatalyst, optic and antibacterial activity. The hydroxyl radical in TiO2 applies to the intensive oxidizing agent, hence TiO2 is suitable to use photocatalytic materials. Black TiO2was prepared through reduction of amorphous TiO2 conducting under H2 which leads to color changes. Its black color is proven that absorbs 100% light across the whole-visible light, drawing enhancement of photocatalytic property. In this study, we aimed to compare the photocatalytic activity of silver ion doped on TiO2(TiO2/Ag+) and silver ion doped on black TiO2(black TiO2/Ag+) under visible light range. TiO2/Ag+ was fabricated following steps. 1) TiO2 was synthesized by a sol-gel method from Titanium tetraisopropoxide (TTIP). 2) Then AgNO3 was added during an aging process step for silver ion doping on the surface of TiO2. Moreover, Black TiO2/Ag+ was obtained same as TiO2/Ag+ except for calcination under H2. The samples were characterized X-ray diffraction (XRD), UV-visible reflectance (UV-vis DRS), and Methylene Blue degradation test. XRD analysis confirmed morphology of TiO2. The band gap of black TiO2/Ag+ was confirmed (2.6 eV) through UV-vis DRS, which was lower than TiO2/Ag+ (2.9 eV). The photocatalytic effect was conducted by methylene blue degradation test. It demonstrated that black TiO2/Ag+ had a photocatalytic effect under UV light also visible light.

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

International Nuclear Information System (INIS)

Sauthier, G.; Ferrer, F.J.; Figueras, A.; Gyoergy, E.

2010-01-01

Nitrogen-doped titanium dioxide (TiO 2 ) thin films were grown on (001) SiO 2 substrates by reactive pulsed laser deposition. A KrF* excimer laser source (λ = 248 nm, τ FWHM ≅ 10 ns, ν = 10 Hz) was used for the irradiations of pressed powder targets composed by both anatase and rutile phase TiO 2 . 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.

Nanoscale Optimization and Statistical Modeling of Photoelectrochemical Water Splitting Efficiency of N-Doped TiO2 Nanotubes

KAUST Repository

Isimjan, Tayirjan T.

2014-12-19

Highly ordered nitrogen-doped titanium dioxide (N-doped TiO2) nanotube array films with enhanced photo-electrochemical water splitting efficiency (PCE) for hydrogen generation were fabricated by electrochemical anodization, followed by annealing in a nitrogen atmosphere. Morphology, structure and composition of the N-doped TiO2 nanotube array films were investigated by FE-SEM, XPS, UV-Vis and XRD. The effect of annealing temperature, heating rate and annealing time on the morphology, structure, and photo-electrochemical property of the N-doped TiO2 nanotube array films were investigated. A design of experiments method was applied in order to minimize the number of experiments and obtain a statistical model for this system. From the modelling results, optimum values for the influential factors were obtained in order to achieve the maximum PCE. The optimized experiment resulted in 7.42 % PCE which was within 95 % confidence interval of the predicted value by the model. © 2014 Springer Science+Business Media.

Preparation of an orthodontic bracket coated with an nitrogen-doped TiO(2-x)N(y) thin film and examination of its antimicrobial performance.

Science.gov (United States)

Cao, Baocheng; Wang, Yuhua; Li, Na; Liu, Bin; Zhang, Yingjie

2013-01-01

A bracket coated with a nitrogen-doped (N-doped) TiO(2-x)N(y) thin film was prepared using the RF magnetron sputtering method. The physicochemical properties of the thin film were measured using X-ray diffraction and energy-dispersive X-ray spectrometry, while the antimicrobial activity of the bracket against common oral pathogenic microbes was assessed on the basis of colony counts. The rate of antimicrobial activity of the bracket coated with nano-TiO(2-x)N(y) thin film against Streptococcus mutans, Lactobacillus acidophilus, Actinomyces viscous, and Candida albicans was 95.19%, 91.00%, 69.44%, and 98.86%, respectively. Scanning electron microscopy showed that fewer microbes adhered to the surface of this newly designed bracket than to the surface of the normal edgewise bracket. The brackets coated with the N-doped TiO(2-x)N(y) thin film showed high antimicrobial and bacterial adhesive properties against normal oral pathogenic bacterial through visible light, which is effective in prevention of enamel demineralization and gingivitis in orthodontic patients.

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)

Dhayal, Marshal; Kapoor, Renu; Sistla, Pavana Goury; Pandey, Ravi Ranjan; Kar, Satabisha; Saini, Krishan Kumar; Pande, Gopal

2014-01-01

Metal ion doped titanium oxide (TiO 2 ) 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 TiO 2 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 TiO 2 were less polar, could support better adhesion, spreading and proliferation of cells. - Highlights: • Electrochemical properties of dopants control the nature of TiO 2 thin films. • A model explains the correlation of dopant properties and behaviour of TiO 2 films. • Dopants with less polar interaction with TiO 2 exhibit better biological activity

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

International Nuclear Information System (INIS)

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

2010-01-01

Anatase Nb-doped TiO 2 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 deg. C in vacuum to form single-phase anatase films. Films with a thickness of 170 nm exhibited a resistivity of 8x10 -4 Ω cm with absorptance less than 5% at a wavelength of 460 nm. Furthermore, the refractive index of the Nb-doped TiO 2 was well matched to that of GaN. These findings indicate that Nb-doped TiO 2 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.

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

International Nuclear Information System (INIS)

Nakao, Shoichiro; Hirose, Yasushi; Hasegawa, Tetsuya

2016-01-01

We studied the effects of reductive annealing on insulating polycrystalline thin films of anatase Nb-doped TiO 2 (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 H 2 -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. (paper)

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

Directory of Open Access Journals (Sweden)

F. X. Xie

2008-01-01

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

Enhanced Optical and Electrical Properties of TiO_2 Buffered IGZO/TiO_2 Bi-Layered Films

International Nuclear Information System (INIS)

Moon, Hyun-Joo; Kim, Daeil

2016-01-01

In and Ga doped ZnO (IGZO, 100-nm thick) thin films were deposited by radio frequency magnetron sputtering without intentional substrate heating on a bare glass substrate and a TiO_2-deposited glass substrate to determine the effect of the thickness of a thin TiO_2 buffer layer on the structural, optical, and electrical properties of the films. The thicknesses of the TiO_2 buffer layers were 5, 10 and 15 nm, respectively. As-deposited IGZO films with a 10 nm-thick TiO_2 buffer layer had an average optical transmittance of 85.0% with lower resistivity (1.83×10-2 Ω cm) than that of IGZO single layer films. The figure of merit (FOM) reached a maximum of 1.44×10-4 Ω-1 for IGZO/10 nm-thick TiO_2 bi-layered films, which is higher than the FOM of 6.85×10-5 Ω-1 for IGZO single layer films. Because a higher FOM value indicates better quality transparent conducting oxide (TCO) films, the IGZO/10 nm-thick TiO_2 bi-layered films are likely to perform better in TCO applications than IGZO single layer films.

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)

Sayilkan, F.; Asiltuerk, M.; Tatar, P.; Kiraz, N.; Sener, S.; Arpac, E.; Sayilkan, H.

2008-01-01

Sn-doped and undoped nano-TiO 2 particles have been synthesized by hydrotermal process without acid catalyst at 225 deg. C in 1 h. Nanostructure-TiO 2 based thin films, contain at different solid ratio of TiO 2 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-TiO 2 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 TiO 2 thin film. The results also proved that malachite green is decomposed catalytically due to the pseudo first-order reaction kinetics

Influence of nitrogen dopants on N-doped TiO2 electrodes and their applications in dye-sensitized solar cells

International Nuclear Information System (INIS)

Guo Wei; Shen Yihua; Boschloo, Gerrit; Hagfeldt, Anders; Ma Tingli

2011-01-01

Highlights: → Three different types of nanocrystalline N-doped TiO 2 synthesized by several nitrogen dopants. → N-doped DSCs achieves a high conversion efficiency of 8.32%. → Ammonia acts as good nitrogen dopants. → Enhanced photocurrent of ca. 36% in N-doped DSCs. → Less charge are needed to get a high open-circuit voltage in N-doped films. - Abstract: Three different types of nanocrystalline, N-doped TiO 2 electrodes were synthesized using several nitrogen dopants through wet methods. The obtained nanocrystalline, N-doped TiO 2 electrodes possessed different crystallite sizes, surface areas, and N-doping amounts. Characterizations were performed to reveal the nitrogen-doping processes for the wet methods using ammonia, urea, and triethylamine as the nitrogen dopants. Additionally, a high conversion efficiency of 8.32% was achieved by the dye-sensitized solar cells, based on the N-doped TiO 2 electrodes. For instance, in comparison with the commercial P25 (5.76%) and pure anatase TiO 2 electrodes (7.14%), significant improvements (44% and 17%, respectively) in the efficiencies were obtained. The findings also indicated that the ammonia nitrogen dopant was more efficient than other two nitrogen dopants. The electron transports, electron lifetimes, and charge recombination in the dye-sensitized N-doped TiO 2 solar cells also differed from those in the pure TiO 2 -based dye-sensitized solar cells (DSCs). Specifically, an enhanced photocurrent of ca. 36% in N-doped DSCs resulted from the synergistic effects of the high dye uptake and the efficient electron transport. Moreover, the relationship between charge and voltage revealed that less charge was needed to get a high open-circuit voltage in the N-doping films.

Dye-sensitized solar cells based on Cr-doped TiO2 nanotube photoanodes

Institute of Scientific and Technical Information of China (English)

M.M.Momeni

2017-01-01

The effect of chromium doping on the photovoltaic efficiency of dye-sensitized solar cells (DSSCs) with anodized TiO2 nanotubes followed by an annealing process was investigated.Cr-doped TiO2 nanotubes (CrTNs) with different amounts of chromium were obtained by anodizing of titanium foils in a single-step process using potassium chromate as the chromium source.Film features were investigated by scanning electron microscopy (SEM),X-ray diffraction (XRD),energy-dispersive X-ray spectroscopy (EDX),and ultraviolet-visible (UV-Vis) spectroscopy.It is clearly seen that highly ordered TiO2 nanotubes are formed in an anodizing solution free of potassium chromate,and with a gradual increase in the potassium chromate concentration,these nanotube structures change to nanoporous and compact films without porosity.The photovoltaic efficiencies of fabricated DSSCs were characterized by a solar cell measurement system via the photocurrent-voltage (Ⅰ-Ⅴ) curves.It is found that the photovoltaic efficiency of DSSCs with CrTNsl sample is improved by more than three times compared to that of DSSCs with undoped TNs.The energy conversion efficiency increases from 1.05 ％ to 3.89 ％ by doping of chromium.

Photocatalysis with chromium-doped TiO2: Bulk and surface doping

KAUST Repository

Ould-Chikh, Samy

2014-04-15

The photocatalytic properties of TiO2 modified by chromium are usually found to depend strongly on the preparation method. To clarify this problem, two series of chromium-doped titania with a chromium content of up to 1.56 wt % have been prepared under hydrothermal conditions: the first series (Cr:TiO2) is intended to dope the bulk of TiO2, whereas the second series (Cr/TiO2) is intended to load the surface of TiO2 with Cr. The catalytic properties have been compared in the photocatalytic oxidation of formic acid. Characterization data provides evidence that in the Cr/TiO2 catalysts chromium is located on the surface of TiO2 as amorphous CrOOH clusters. In contrast, in the Cr:TiO 2 series, chromium is mostly dissolved in the titania lattice, although a minor part is still present on the surface. Photocatalytic tests show that both series of chromium-doped titania demonstrate visible-light-driven photo-oxidation activity. Surface-doped Cr/TiO2 solids appear to be more efficient photocatalysts than the bulk-doped Cr:TiO2 counterparts. It\\'s classified! The photocatalytic properties of TiO2 modified by chromium depend strongly on the preparation method. To clarify this problem, two types of modified titania are discussed: one with CrIII doped in the bulk and one with CrOOH clusters on the TiO2 surface (see picture). Both series show visible-light-driven photo-oxidation activity. However, surface modification appears to be a more efficient strategy. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Composition and crystal structure of N doped TiO2 film deposited at different O2 flow rate by direct current sputtering.

Science.gov (United States)

Ding, Wanyu; Ju, Dongying; Chai, Weiping

2011-06-01

N doped Ti02 films were deposited by direct current pulse magnetron sputtering system at room temperature. The influence of 02 flow rate on the crystal structure of deposited films was studied by Stylus profilometer, X-ray photoelectron spectroscopy, and X-ray diffractometer. The results indicate that the 02 flow rate strongly controls the growth behavior and crystal structure of N doped Ti02 film. It is found that N element mainly exists as substitutional doped state and the chemical stiochiometry is near to TiO1.68±0.06N0.11±0.01 for all film samples. N doped Ti02 film deposited with 2 sccm (standard-state cubic centimeter per minute) 02 flow rate is amorphous structure with high growth rate, which contains both anatase phase and rutile phase crystal nucleuses. In this case, the film displays the mix-phase of anatase and rutile after annealing treatment. While N doped Ti02 film deposited with 12 cm(3)/min 02 flow rate displays anatase phase before and after annealing treatment. And it should be noticed that no TiN phase appears for all samples before and after annealing treatment. Copyright © 2011 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Structural study of TiO2-based transparent conducting films

International Nuclear Information System (INIS)

Hitosugi, T.; Yamada, N.; Nakao, S.; Hatabayashi, K.; Shimada, T.; Hasegawa, T.

2008-01-01

We have investigated microscopic structures of sputter and pulsed laser deposited (PLD) anatase Nb-doped TiO 2 transparent conducting films, and discuss what causes the degradation of resistivity in sputter-deposited films. Cross-sectional transmission electron microscope and polarized optical microscope images show inhomogeneous intragrain structures and small grains of ∼10 μm in sputter-deposited films. From comparison with PLD films, these results suggest that homogeneous film growth is the important factor to obtain highly conducting sputter-deposited film

Pt Catalyst Supported within TiO2 Mesoporous Films for Oxygen Reduction Reaction

International Nuclear Information System (INIS)

Huang, Dekang; Zhang, Bingyan; Bai, Jie; Zhang, Yibo; Wittstock, Gunther; Wang, Mingkui; Shen, Yan

2014-01-01

In this study, dispersed Pt nanoparticles into mesoporous TiO 2 thin films are fabricated by a facile electrochemical deposition method as electro-catalysts for oxygen reduction reaction. The mesoporous TiO 2 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/TiO 2 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/TiO 2 electrode. Further study demonstrates the stability of the Pt catalyst supported within TiO 2 mesoporous films for the oxygen reduction reaction

Carbamazepine degradation using a N-doped TiO_2 coated photocatalytic membrane reactor: Influence of physical parameters

International Nuclear Information System (INIS)

Horovitz, Inna; Avisar, Dror; Baker, Mark A.; Grilli, Rossana; Lozzi, Luca; Di Camillo, Daniela; Mamane, Hadas

2016-01-01

Highlights: • UV–vis N-doped TiO_2 was deposited by sol-gel onto Al_2O_3 microfiltration membranes. • Coating decreased permeability by 50 and 12% for 200- and 800-nm Al_2O_3 membranes. • Flow through membrane results in higher reaction rates compared to flow on top. • Higher vis photocatalytic activity for N-doped TiO_2 vs. non-doped TiO_2 membranes. • Mass transfer is a critical parameter for the design of immobilized PMR. - Abstract: Commercial α-Al_2O_3 photocatalytic membranes with a pore size of 200 and 800-nm were coated with N-doped TiO_2 photocatalytic film using a sol-gel technique for concurrent bottom-up filtration and photocatalytic oxidation. X-ray diffraction confirmed that the deposited N-doped TiO_2 films are in the form of anatase with 78–84% coverage of the membrane surface. The concentration of N found by X-ray photoelectron spectroscopy was in the range of 0.3–0.9 atomic percentage. Membrane permeability after coating decreased by 50% and 12% for the 200- and 800-nm membrane substrates, respectively. The impact of operational parameters on the photocatalytic activity (PCA) of the N-doped TiO_2-coated membranes was examined in a laboratory flow cell based on degradation of the model micropollutant carbamazepine, using a solar simulator as the light source. The significant gap in degradation rate between flow through the membrane and flow on the surface of the membrane was attributed both to the hydraulic effect and in-pore PCA. N-doped TiO_2-coated membranes showed enhanced activity for UV wavelengths, in addition to activity under visible light. Experiments of PCA under varying flow rates concluded that the process is in the mass-transfer control regime. Carbamazepine removal rate increased with temperature, despite the decrease in dissolved oxygen concentration.

Enhanced electrochromic properties of TiO2 nanoporous film prepared based on an assistance of polyethylene glycol

Science.gov (United States)

Xu, Shunjian; Luo, Xiaorui; Xiao, Zonghu; Luo, Yongping; Zhong, Wei; Ou, Hui; Li, Yinshuai

2017-01-01

Polyethylene glycol (PEG) was employed as pore-forming agent to prepare TiO2 nanoporous film based on spin-coating a TiO2 nanoparticle mixed paste on fluorine doped tin oxide (FTO) glass. The electrochromic and optical properties of the obtained TiO2 film were investigated by cyclic voltammetry (CV), chronoamperometry (CA) and UV-Vis spectrophotometer. The results show that the PEG in the mixed paste endows the TiO2 film with well-developed porous structure and improves the uniformity of the TiO2 film, which are helpful for the rapid intercalation and extraction of lithium ions within the TiO2 film and the strengthening of the diffuse reflection of visible light in the TiO2 film. As a result, the TiO2 film derived from the mixed paste with PEG displays higher electrochemical activity and more excellent electrochromic performances compared with the TiO2 film derived from the mixed paste without PEG. The switching times of coloration/bleaching are respectively 10.16/5.65 and 12.77/6.13 s for the TiO2 films with PEG and without PEG. The maximum value of the optical contrast of the TiO2 film with PEG is 21.2% while that of the optical contrast of the TiO2 film without PEG is 14.9%. Furthermore, the TiO2 film with PEG has better stability of the colored state than the TiO2 film without PEG.

Nanoscale Optimization and Statistical Modeling of Photoelectrochemical Water Splitting Efficiency of N-Doped TiO2 Nanotubes

KAUST Repository

Isimjan, Tayirjan T.; Trifkovic, Milana; Abdullahi, Inusa; Rohani, Sohrab M F; Ray, Ajay

2014-01-01

Highly ordered nitrogen-doped titanium dioxide (N-doped TiO2) nanotube array films with enhanced photo-electrochemical water splitting efficiency (PCE) for hydrogen generation were fabricated by electrochemical anodization, followed by annealing

Al2O3 doping of TiO2 electrodes and applications in dye-sensitized solar cells

International Nuclear Information System (INIS)

Eom, Tae Sung; Kim, Kyung Hwan; Bark, Chung Wung; Choi, Hyung Wook

2014-01-01

Dye-sensitized solar cells (DSSCs) have been intensively studied since their discovery in 1991. DSSCs have been extensively researched over the past decades as cheaper alternatives to silicon solar cells due to their high energy-conversion efficiency and their low production cost. However, some problems need to be solved in order to enhance the efficiency of DSSCs. In particular, the electron recombination that occurs due to the contact between the transparent conductive oxide (TCO) and a redox electrolyte is one of the main limiting factors of efficiency. In this work, we report for the first time the improvement of the photovoltaic characteristics of DSSCs by doping TiO 2 with Al 2 O 3 . DSSCs were constructed using composite particles of Al 2 O 3 -doped TiO 2 and TiO 2 nanoparticles. The DSSCs using Al 2 O 3 showed the maximum conversion efficiency of 6.29% due to effective electron transport. DSSCs based on Al 2 O 3 -doped TiO 2 films showed better photovoltaic performance than cells fabricated with only TiO 2 nanoparticles. This result is attributed to the prevention of electron recombination between electrons in the TiO 2 conduction band with holes in the dye or the electrolyte. There mechanism is suggested based on impedance results, which indicated improved electron transport at the TiO 2 /dye/electrolyte interface.

Structural, optical and ferromagnetic properties of Cr doped TiO2 nanoparticles

International Nuclear Information System (INIS)

Choudhury, Biswajit; Choudhury, Amarjyoti

2013-01-01

Graphical abstract: Doping of Cr 3+ distorts the lattice of TiO 2 , generate oxygen vacancies and create d-band states in the mid band gap of TiO 2 . Incorporation of Cr 3+ also imparts magnetism in non-magnetic TiO 2 by undergoing coupling with the neighboring oxygen vacancies. -- Highlights: • Incorporation of Cr 3+ increases the concentration of oxygen vacancies in TiO 2 nanoparticles. • Doped TiO 2 nanoparticles contain absorption peaks corresponding to d–d transition of Cr 3+ into TiO 2 . • Pure and doped TiO 2 nanoparticles contain emission peaks related to oxygen vacancies. • Pure TiO 2 shows diamagnetism while Cr doped TiO 2 shows ferromagnetism. • The ferromagnetism is due to the interaction of Cr 3+ ions via oxygen vacancies. -- Abstract: Cr doped TiO 2 nanoparticles are prepared with three different concentrations of chromium, 1.5%, 3.0% and 4.5 mol% respectively. Doping decreases the crystallinity and increases the width of the X-ray diffraction peak. The Raman active E g peak of TiO 2 nanoparticles become asymmetric and shifted to higher energy on doping of 4.5% chromium. Electron paramagnetic resonance spectra reveal the presence of Cr 3+ in the host TiO 2 matrix. The absorption spectra of Cr doped TiO 2 nanoparticles contain absorption peaks corresponding to d–d transition of Cr 3+ in octahedral coordination. Most of the visible emission peaks are due to the electrons trapped in the oxygen vacancy centers. Undoped TiO 2 nanoparticles show diamagnetism at room temperature while all chromium doped samples show ferromagnetism. The magnetization of the doped samples increases at 1.5% and 3.0% and decreases at 4.5%. The ferromagnetism arises owing to the interaction of the neighboring Cr 3+ ions via oxygen vacancies. The decrease of magnetization at the highest doping is possibly due to the antiferromagnetic interactions of Cr 3+ pairs or due to Cr 3+ -O 2− -Cr 3+ superexchange interaction in the lattice

Synthesis of photosensitive nanograined TiO2 thin films by SILAR method

International Nuclear Information System (INIS)

Patil, U.M.; Gurav, K.V.; Joo, Oh-Shim; Lokhande, C.D.

2009-01-01

Nanocrystalline TiO 2 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 TiO 2 thin films. The heat-treated film showed conversion efficiency of 0.047% in photoelectrochemical cell with 1 M NaOH electrolyte.

A fast and effective method for N-doping TiO2 by post treatment with liquid ammonia: visible light photocatalysis

International Nuclear Information System (INIS)

Powell, Michael J.; Palgrave, Robert G.; Dunnill, Charles W.; Parkin, Ivan P.

2014-01-01

TiO 2 thin films prepared by sol–gel synthesis were N-doped by post treating with liquid ammonia and annealing at 500 °C. Characterisation by X-ray diffraction and Raman spectroscopy confirmed that the anatase crystal type was retained and present in all samples. Scanning electron microscopy showed that treatment with liquid ammonia had no significant effect on the film morphology. Functional testing under filtered while light conditions involving water contact angle, and the photo destruction of both Resazurin and Stearic acid showed the ammonia treated samples to be active visible light photocatalysts in contrast to the pure TiO 2 and the blank controls. X-ray Photoelectron Spectroscopy studies indicate the presence of interstitial nitrogen (N 1s = 400 eV) suggesting that the origin of the enhanced photocatalytic activity is most likely due to oxygen vacancies created by the interstitial nitrogen incorporation. This synthesis method utilises a simple, inexpensive and highly effective post treatment route to N-dope TiO 2 and produces visible light photocatalysts with potential applications in self-cleaning and healthcare environments. - Highlights: • Synthesis and characterisation of N-doped TiO 2 thin films • N-doping by a post treatment with liquid ammonia • Enhanced photocatalytic activity • Easy enhancement of current TiO 2 based technologies

In-situ co-doping of sputter-deposited TiO2:WN films for the development of photoanodes intended for visible-light electro-photocatalytic degradation of emerging pollutants

Science.gov (United States)

Delegan, N.; Pandiyan, R.; Komtchou, S.; Dirany, A.; Drogui, P.; El Khakani, M. A.

2018-05-01

We report on the magnetron sputtering deposition of in-situ codoped TiO2:WN films intended for electro-photocatalytic (EPC) applications under solar irradiation. By varying the RF-magnetron sputtering deposition parameters, we were able to tune the in-situ incorporation of both N and W dopants in the TiO2 films over a wide concentration range (i.e., 0-9 at. % for N and 0-3 at. % for W). X-ray photoelectron spectroscopy analysis revealed that both dopants are mostly of a substitutional nature. The analysis of the UV-Vis transmission spectra of the films confirmed that the optical bandgap of both TiO2:N and TiO2:WN films can be significantly narrowed (from 3.2 eV for undoped-TiO2 down to ˜2.3 eV for the doped ones) by tuning their dopant concentrations. We were thus able to pinpoint an optimal window for both dopants (N and W) where the TiO2:WN films exhibit the narrowest bandgap. Moreover, the optimal codoping conditions greatly reduce the recombination defect state density compared to the monodoped TiO2:N films. These electronically passivated TiO2:WN films are shown to be highly effective for the EPC degradation of atrazine (pesticide pollutant) under sunlight irradiation (93% atrazine degraded after only 30 min of EPC treatment). Indeed, the optimally codoped TiO2:WN photoanodes were found to be more efficient than both the undoped-TiO2 and equally photosensitized TiO2:N photoanodes (by ˜70% and ˜25%, respectively) under AM1.5 irradiation.

Nanoimprinted distributed feedback lasers comprising TiO2 thin films

DEFF Research Database (Denmark)

Vannahme, Christoph; Smith, Cameron; Leung, Michael C.

2013-01-01

Design guidelines for optimizing the sensing performance of nanoimprinted second order distributed feedback dye lasers are presented. The guidelines are verified by experiments and simulations. The lasers, fabricated by UV-nanoimprint lithography into Pyrromethene doped Ormocomp thin films on glass......, have their sensor sensitivity enhanced by a factor of up to five via the evaporation of a titanium dioxide (TiO2) waveguiding layer. The influence of the TiO2 layer thickness on the device sensitivity is analyzed with a simple model that accurately predicts experimentally measured wavelength shifts...

Influence of Zr doping on structure and morphology of TiO2 nanorods prepared using hydrothermal method

Science.gov (United States)

Muslimin, Masliana; Jumali, Mohammad Hafizuddin; Tee, Tan Sin; Beng, Lee Hock; Hui, Tan Chun; Chin, Yap Chi

2018-04-01

The aim of this work is to investigate the effect of Zr doping on TiO2 nanostructure. TiO2 nanorods thin films with different Zr-doping concentrations (6 × 10-3 M, 13 × 10-3 M and 25 × 10-3 M) were successfully prepared using a simple hydrothermal method. The structural and morphological properties of the samples were evaluated using XRD and FESEM respectively. The XRD results revealed that the TiO2 in all samples stabilized as rutile phase. The FESEM micrographs confirmed that TiO2 exist as square like nanorods with blunt tips. Although the crystallographic nature remains unchanged, the introduction of Zr has altered the surface density, structure and morphology of TiO2 which subsequently will have significant effect on its properties.

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)

Sayilkan, F.; Asiltuerk, M.; Tatar, P.; Kiraz, N.; Arpac, E.; Sayilkan, H.

2007-01-01

Nanostructure Sn 4+ -doped TiO 2 based mono and double layer thin films, contain 50% solid ratio of TiO 2 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. Sn 4+ -doped nano-TiO 2 particle a doping ratio of about 5[Sn 4+ /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-TiO 2 particles are fully anatase crystalline form and are easily dispersed in water. The results also reveal that the coated surfaces have hydrophilic property

Mild solution-processed metal-doped TiO2 compact layers for hysteresis-less and performance-enhanced perovskite solar cells

Science.gov (United States)

Liang, Chao; Li, Pengwei; Zhang, Yiqiang; Gu, Hao; Cai, Qingbin; Liu, Xiaotao; Wang, Jiefei; Wen, Hua; Shao, Guosheng

2017-12-01

TiO2 is extensively used as electron-transporting material on perovskite solar cells (PSCs). However, traditional TiO2 processing method needs high annealing temperature (>450 °C) and pure TiO2 suffers from low electrical mobility and poor conductivity. In this study, a general one-pot solution-processed method is devised to grow uniform crystallized metal-doped TiO2 thin film as large as 15 × 15 cm2. The doping process can be controlled effectively via a series of doping precursors from niobium (V), tin (IV), tantalum (V) to tungsten (VI) chloride. As far as we know, this is so far the lowest processing temperature for metal-doped TiO2 compact layers, as low as 70 °C. The overall performance of PSCs employing the metal-doped TiO2 layers is significantly improved in term of hysteresis effect, short circuit current, open-circuit voltage, fill factor, power conversion efficiency, and device stability. With the insertion of metal ions into TiO2 lattice, the corresponding CH3NH3PbI3 PSC leads to a ∼25% improved PCE of over 16% under irradiance of 100 mW cm-2 AM1.5G sunlight, compared with control device. The results indicate that this mild solution-processed metal-doped TiO2 is an effective industry-scale way for fabricating hysteresis-less and high-performance PSCs.

TiO2 coated SnO2 nanosheet films for dye-sensitized solar cells

International Nuclear Information System (INIS)

Cai Fengshi; Yuan Zhihao; Duan Yueqing; Bie Lijian

2011-01-01

TiO 2 -coated SnO 2 nanosheet (TiO 2 -SnO 2 NS) films about 300 nm in thickness were fabricated on fluorine-doped tin oxide glass by a two-step process with facile solution-grown approach and subsequent hydrolysis of TiCl 4 aqueous solution. The as-prepared TiO 2 -SnO 2 NSs were characterized by scanning electron microscopy and X-ray diffraction. The performances of the dye-sensitized solar cells (DSCs) with TiO 2 -SnO 2 NSs were analyzed by current-voltage measurements and electrochemical impedance spectroscopy. Experimental results show that the introduction of TiO 2 -SnO 2 NSs can provide an efficient electron transition channel along the SnO 2 nanosheets, increase the short current density, and finally improve the conversion efficiency for the DSCs from 4.52 to 5.71%.

Mn-doped CdS quantum dots sensitized hierarchical TiO2 flower-rod for solar cell application

International Nuclear Information System (INIS)

Yu, Libo; Li, Zhen; Liu, Yingbo; Cheng, Fa; Sun, Shuqing

2014-01-01

A double-layered TiO 2 film which three dimensional (3D) flowers grown on highly ordered self-assembled one dimensional (1D) TiO 2 nanorods was synthesized directly on transparent fluorine-doped tin oxide (FTO) conducting glass substrate by a facile hydrothermal method and was applied as photoanode in Mn-doped CdS quantum dots sensitized solar cells (QDSSCs). The 3D TiO 2 flowers with the increased surface areas can adsorb more QDs, which increased the absorption of light; meanwhile 1D TiO 2 nanorods beneath the flowers offered a direct electrical pathway for photogenerated electrons, accelerating the electron transfer rate. A typical type II band alignment which can effectively separate photogenerated excitons and reduce recombination of electrons and holes was constructed by Mn-doped CdS QDs and TiO 2 flower-rod. The incident photon-to-current conversion efficiency (IPCE) of the Mn-doped CdS/TiO 2 flower-rod solar cell reached to 40% with the polysulfide electrolyte filled in the solar cell. The power conversion efficiency (PCE) of 1.09% was obtained with the Mn-doped CdS/TiO 2 flower-rod solar cell under one sun illumination (AM 1.5G, 100 mW/cm 2 ), which is 105.7% higher than that of the CdS/TiO 2 nanorod solar cell (0.53%).

Synthesis and photocatalytic activity of graphene based doped TiO2 nanocomposites

International Nuclear Information System (INIS)

Gu, Yongji; Xing, Mingyang; Zhang, Jinlong

2014-01-01

Graphical abstract: - Highlights: • Graphene based doped TiO 2 nanocomposites were prepared. • The intimate contact between doped TiO 2 and graphene is achieved simultaneously. • These nanocomposites showed higher photocatalytic activity than TiO 2 and doped TiO 2 . • Photocatalytic mechanism was explained thoroughly. - Abstract: The nanocomposites of reduced graphene oxide based nitrogen doped TiO 2 (N–TiO 2 –RGO) and reduced graphene oxide based nitrogen and vanadium co-doped TiO 2 (N, V–TiO 2 –RGO) were prepared via a facile hydrothermal reaction of graphene oxide and TiO 2 in a water solvent. In this hydrothermal treatment, the reduction of graphene oxide and the intimate contact between nitrogen doped TiO 2 (N–TiO 2 ) or nitrogen and vanadium co-doped TiO 2 (N,V–TiO 2 ) and the RGO sheet is achieved simultaneously. Both N–TiO 2 –RGO and N,V–TiO 2 –RGO nanocomposites exhibit much higher visible light photocatalytic activity than N–TiO 2 and N,V–TiO 2 , and the order of visible light photocatalytic activity is N,V–TiO 2 –RGO > N–TiO 2 –RGO > N,V–TiO 2 > N–TiO 2 > TiO 2 . According to the characterization, the enhanced photocatalytic activity of the nanocomposites is attributed to reasons, such as enhancement of adsorption of pollutants, light absorption intensity, minimizing the recombination of photoinduced electrons and holes and more excited states of these nanocomposites under visible light irradiation. Overall, this work provides a more marked contrast of graphene based semiconductor nanocomposites and a more comprehensive explanation of the mechanism

Thin film nano-photocatalyts with low band gap energy for gas phase degradation of p-xylene: TiO2 doped Cr, UiO66-NH2 and LaBO3 (B  =  Fe, Mn, and Co)

Science.gov (United States)

Loc Luu, Cam; Thuy Van Nguyen, Thi; Nguyen, Tri; Nguyen, Phung Anh; Hoang, Tien Cuong; Ha, Cam Anh

2018-03-01

By dip-coating technique the thin films of nano-photocatalysts TiO2, Cr-doped TiO2, LaBO3 perovskites (B  =  Fe, Mn, and Co) prepared by sol-gel method, and UiO66-NH2 prepared by a solvothermal were obtained and employed for gas phase degradation of p-xylene. Physicochemical characteristics of the catalysts were examined by the methods of BET, SEM, TEM, XRD, FT-IR, TGA, Raman and UV-vis spectroscopies. The thickness of film was determined by a Veeco-American Dektek 6M instrument. The activity of catalysts was evaluated in deep photooxidation of p-xylene in a microflow reactor at room temperature with the radiation sources of a UV (λ  =  365 nm) and LED lamps (λ  =  400-510 nm). The obtained results showed that TiO2 and TiO2 doped Cr thin films was featured by an anatase phase with nanoparticles of 10-100 nm. Doping TiO2 with 0.1%mol Cr2O3 led to reduce band gap energy from 3.01 down to 1.99 eV and extend the spectrum of photon absorption to the visible region (λ  =  622 nm). LaBO3 perovkite thin films were also featured by a crystal phase with average particle nanosize of 8-40 nm, a BET surface area of 17.6-32.7 m2 g-1 and band gap energy of 1.87-2.20 eV. UiO66-NH2 was obtained in the ball shape of 100-200 nm, a BET surface area of 576 m2 g-1 and a band gap energy of 2.83 eV. The low band gap energy nano-photocatalysts based on Cr-doped TiO2 and LaBO3 perovskites exhibited highly stable and active for photo-degradation of p-xylene in the gas phase under radiation of UV-vis light. Perovskite LaFeO3 and Cr-TiO2 thin films were the best photocatalysts with a decomposition yield being reached up to 1.70 g p-xylene/g cat.

Probing Photocatalytic Characteristics of Sb-Doped TiO2 under Visible Light Irradiation

Directory of Open Access Journals (Sweden)

Lingjing Luo

2014-01-01

Full Text Available Sb-doped TiO2 nanoparticle with varied dopant concentrations was synthesized using titanium tetrachloride (TiCl4 and antimony chloride (SbCl3 as the precursors. The properties of Sb-doped TiO2 nanoparticles were characterized by X-ray diffraction (XRD, scanning electron microscope (SEM, fluorescence spectrophotometer, and Uv-vis spectrophotometer. The absorption edge of TiO2 nanoparticles could be extended to visible region after doping with antimony, in contrast to the UV absorption of pure TiO2. The results showed that the photocatalytic activity of Sb-doped TiO2 nanoparticles was much more active than pure TiO2. The 0.1% Sb-doped TiO2 nanoparticles demonstrated the best photocatalytic activity which was better than that of the Degussa P25 under visible light irradiation using terephthalic acid as fluorescent probe. The effects of Sb dopant on the photocatalytic activity and the involved mechanism were extensively investigated in this work as well.

Fabrication of La-doped TiO2 Film Electrode and investigation of its electrocatalytic activity for furfural reduction

International Nuclear Information System (INIS)

Wang, Fengwu; Xu, Mai; Wei, Lin; Wei, Yijun; Hu, Yunhu; Fang, Wenyan; Zhu, Chuan Gao

2015-01-01

Lanthanum trivalent ions (La 3+ ) doped nano-TiO 2 film electrode was prepared by the sol–gel method. The prepared electrode was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV). The electrocatalytic properties of the roughened TiO 2 film electrode towards the electrocatalytic reduction of furfural to furfural alcohol were evaluated by CV and preparative electrolysis experiments. The results of the optimum molar ratio of La: Ti was 0.005:1. Experimental evidence was presented that the La nano-TiO 2 electrode exhibited higher electrocatalytic activity for the reduction of furfural than the undoped nano-TiO 2 electrode in N,N-dimethylformamide medium. Bulk electrolysis studies were also carried out for the reduction of furfural and the product was confirmed by NMR

Optical properties of ZrO2, SiO2 and TiO2-SiO2 xerogels and coatings doped with Eu3+ and Eu2+

Directory of Open Access Journals (Sweden)

Gonçalves Rogéria R.

1999-01-01

Full Text Available Eu3+ doped bulk monoliths and thin films were obtained by sol-gel methods in the ZrO2, SiO2 and SiO2-TiO2 systems. Eu3+ 5D0 ® 7FJ emission and decay time characteristics were measured during the entire experimental preparation route from the initial sol to the final xerogels. The crystalline phases identified were tetragonal ZrO2 and mixtures of rutile and anatase TiO2 at high temperature treatments in bulk samples. Good quality thin films were obtained for all systems by dip-coating optical glasses (Schott BK270. The same spectroscopic features were observed either for the bulk monoliths or the films. By appropriate heat treatments under H2 atmosphere Eu2+ containing samples could be obtained in the SiO2-TiO2 system.

Tailoring luminescence properties of TiO2 nanoparticles by Mn doping

International Nuclear Information System (INIS)

Choudhury, B.; Choudhury, A.

2013-01-01

TiO 2 nanoparticles are doped with three different concentrations of Mn, 2%, 4% and 6% respectively. Absorption edge of TiO 2 is shifted from UV to visible region on amplification of Mn content. Room temperature photoluminescence spectra, excited at 320 nm, exhibit band edge and visible emission peaks associated with self trapped excitons, oxygen defects, etc. Doping of Mn increases the width and decreases the intensity of the UV emission peak. Potential fluctuations of impurities increase the width and auger type non-radiative recombination decreases the intensity of the UV emission peak. The intensity ratio of the UV to defect emission band decreases on doping, indicating degradation of structural quality. Excitation of pure and doped nanoparticles at 390 nm results in Mn 2+ emission peaks at 525 nm and 585 nm respectively. Photoluminescence excitation spectra also indicate the presence of Mn 2+ in the crystalline environment of TiO 2 . The oxygen defects and Mn related impurities act as efficient trap centers and increases the lifetime of the charge carriers. -- Highlights: ► Doping of Mn increases the d-spacing of TiO 2 nanoparticles. ► Characteristic d–d electronic transition of Mn 2+ is observed in the absorption spectra. ► Doping of Mn quenches the UV and visible emission peaks of TiO 2 . ► Photoexcitation at 390 nm generates emission peaks of Mn 2+

Nb and Ta Co-Doped TiO2 Transparent Conductive Thin Films by Magnetron Sputtering: Fabrication, Structure, and Characteristics

Science.gov (United States)

Liu, Yang; Peng, Qian; Qiao, Yadong; Yang, Guang

2018-06-01

Nb and Ta co-doped anatase titanium dioxide (NTTO) nanocrystalline thin films were deposited on quartz and Si (100) substrates by RF magnetron sputtering. The influence of RF power on the growth, structure, morphology, and properties of the samples are discussed in detail. X-ray diffraction measurements show that the films are polycrystalline with anatase tetragonal structure, which is further confirmed by Raman spectroscopy analysis. Meanwhile, Raman spectroscopy results indicate that the peak width of E g(1) mode, which is directly correlated to the carrier density, changes obviously with RF power. It is found that the substitution of Nb5+ and Ta5+ at Ti site is significantly improved with the increase of RF power from 150 W to 210 W. For the sample deposited at 210 W, the optical transmittance is above 82% in the visible range and the electrical resistivity is as low as 1.3 × 10-3 Ω cm with carrier density of 1.1 × 1021 cm-3 and Hall mobility of 4.5 cm2 V-1 s-1. The optical and electrical properties of NTTO thin films can be compared to those of Nb or Ta doped anatase TiO2. However, co-doping with Nb and Ta gives a possible platform to complement the limitations of each individual dopant.

Remarkable optical red shift and extremely high optical absorption coefficient of V-Ga co-doped TiO2

Science.gov (United States)

Deng, Quanrong; Han, Xiaoping; Gao, Yun; Shao, Guosheng

2012-07-01

A first attempt has been made to study the effect of codoping of transition metal and sp metal on the electronic structure and associated optical properties of TiO2, through V-Ga codoped thin films. V-Ga codoped rutile TiO2 films were fabricated on fused quartz substrates using pulsed laser ablation, followed by heat treatment at high temperatures. Gigantic redshift in the optical absorption edge was observed in V-Ga co-doped TiO2 materials, from UV to infrared region with high absorption coefficient. Through combined structural characterization and theoretical modeling, this is attributed to the p-d hybridization between the two metals. This leads to additional energy bands to overlap with the minimum of the conduction band, leading to remarkably narrowed band gap free of mid-gap states. The direct-gap of the co-doped phase is key to the remarkably high optical absorption coefficient of the coped titania.

Microwave-assisted synthesis of C-doped TiO2 and ZnO hybrid nanostructured materials as quantum-dots sensitized solar cells

Science.gov (United States)

Rangel-Mendez, Jose R.; Matos, Juan; Cházaro-Ruiz, Luis F.; González-Castillo, Ana C.; Barrios-Yáñez, Guillermo

2018-03-01

The microwave-assisted solvothermal synthesis of C-doped TiO2 and ZnO hybrid materials was performed. Saccharose, titanium isopropoxide and zinc acetate were used as organic and inorganic sources for the synthesis. The influence of temperature and reaction time on the textural and optoelectronic properties of the hybrid materials was verified. Carbon quantum-dots of TiO2 and ZnO nanostructured spheres were obtained in a second pot by controlled calcination steps of the precursor hybrid materials. A carefully characterization by adsorption-desorption N2 isotherms, XRD, XPS, SEM, UV-vis/DR and electro- and photo-electrochemistry properties of the carbon quantum-dots TiO2 and ZnO spheres was performed. The photoelectrochemical activity of TiO2-C and ZnO-C films proved to be dependent on the conditions of synthesis. It was found a red-shift in the energy band gap of the semiconductors with values of 3.02 eV and 3.13 eV for the TiO2-C and ZnO-C, respectively, clearly lower than those on bare semiconductors, which is associated with the C-doping effect. From the photo-electrochemistry characterization of C-doped TiO2 and ZnO films can be concluded that the present materials have potential applications as photoelectrodes for quantum-dots sensitized solar cells.

W-doped TiO2 photoanode for high performance perovskite solar cell

International Nuclear Information System (INIS)

Liu, Jinwang; Zhang, Jing; Yue, Guoqiang; Lu, Xingwei; Hu, Ziyang; Zhu, Yuejin

2016-01-01

Titanium dioxide (TiO 2 ) with dispersed W-doping shows its capability for efficient electron collection from perovskite to TiO 2 in perovskite solar cell. The conduction band (CB) of TiO 2 moves downward (positive shift) with increasing the tungsten (W) content, which enlarges the energy gap between the CB of TiO 2 and the perovskite. Thus, the efficiency of electron injection from perovskite to TiO 2 is increased. Due to the increased electron injection, W-doped TiO 2 (≤0.2% W content) enhances the short-circuit photocurrent (J sc ) of perovskite solar cell and improves the performance of perovskite solar cell. Perovskite solar cell with 0.1% W-doped photoanode obtains the highest power conversion efficiency (η = 10.6%), which shows enhancement by 13% in J sc and by 17% in η, as compared with the undoped TiO 2 perovskite solar cell.

Unconventional cells of TiO2 doped with erbium

International Nuclear Information System (INIS)

Ribeiro, P.C.; Campos, R.D.; Oliveira, A.S.; Wellen, R.; Diniz, V.C.S.; Costa, A.C.F.M. da

2016-01-01

The technology used in TiO_2 solar cells is in constant improvement, new configurations have been developed, aiming practicality and leading to efficiency increase of photovoltaic devices. This paper proposes a new technology for the production of solar cells in order to investigate a better utilization of solar spectrum of TiO2 doped with erbium (Er"3"+), proven by energetic conversion. The Ti_0_,_9Er_0_,_1O2 system was obtained by Pechini method. Nanoparticles have a crystallite size 65.30 nm and surface area 118.48 m"2/g. These characteristics are essential for the formation of the film to be deposited on the conductive glass substrate constituting the cell's photoelectrode. The other side of the cell is the platinum counter electrode. The cell will have the faces sealed by a thermoplastic and, finally the electrolyte will be inserted, then they will be electrically evaluated through energy efficiency and confronted with the literature data base. (author)

One-step preparation and photocatalytic performance of vanadium doped TiO2 coatings

International Nuclear Information System (INIS)

Vasilić, R.; Stojadinović, S.; Radić, N.; Stefanov, P.; Dohčević-Mitrović, Z.; Grbić, B.

2015-01-01

In this paper, we have investigated one-step preparation of vanadium doped TiO 2 coatings formed by plasma electrolytic oxidation (PEO) of titanium in electrolyte containing 10 g/L Na 3 PO 4 ·12H 2 O + 0.5 g/L NH 4 VO 3 . The morphology, phase structure, and elemental composition of the formed coatings were characterized by atomic force microscopy (AFM), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS) techniques. Ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS) was employed to evaluate the band gap energy of obtained coatings. Vanadium doped TiO 2 coatings are partly crystallized and mainly composed of anatase phase TiO 2 , with up to about 2 wt% of vanadium present in the surface layer of the oxide. The valence band photoelectron spectra and UV–Vis DRS showed that vanadium doped TiO 2 coatings exhibit notable red shift with respect to the pure TiO 2 coatings. The photocatalytic activity was evaluated by monitoring the degradation of methyl orange under simulated sunlight conditions. Photocatalytic activity of vanadium doped TiO 2 coatings increases with PEO time. Prolonged PEO times result in higher roughness of obtained coatings, thus increasing surface area available for methyl orange degradation. Vanadium doped TiO 2 coatings obtained after 180 s of PEO time exhibit the best photocatalytic activity and about 67% of methyl orange is degraded after 12 h of irradiation under simulated sunlight. - Highlights: • One-step preparation of V-doped TiO 2 coatings in 10 g/L Na 3 PO 4 ·12H 2 O + 0.5 g/L NH 4 VO 3 . • Properties of obtained coatings strongly depend on microdischarge characteristics. • Band gap of V-doped TiO 2 coatings is shifted towards red side of the spectrum. • V-doped TiO 2 coatings have better photocatalytic activity than pure TiO 2 . • After 12 h of simulated sunlight irradiation, 67% of methyl orange was decomposed

Synthesis and Photocatalytic Activity of Mo-Doped TiO2 Nanoparticles

Directory of Open Access Journals (Sweden)

Ji-guo Huang

2015-01-01

Full Text Available The undoped and Mo-doped TiO2 nanoparticles were synthesized by sol-gel method. The as-prepared samples were characterized by X-ray diffraction (XRD, diffuse reflectance UV-visible absorption spectra (UV-vis DRS, X-ray photoelectron spectra (XPS, and transmission electron microscopy (TEM. The photocatalytic activity was evaluated by photocatalytic degradation of methylene blue under irradiation of a 500 W xenon lamp and natural solar light outdoor. Effects of calcination temperatures and Mo doping amounts on crystal phase, crystallite size, lattice distortion, and optical properties were investigated. The results showed that most of Mo6+ took the place of Ti4+ in the crystal lattice of TiO2, which inhibited the growth of crystallite size, suppressed the transformation from anatase to rutile, and led to lattice distortion of TiO2. Mo doping narrowed the band gap (from 3.05 eV of TiO2 to 2.73 eV of TiMo0.02O and efficiently increased the optical absorption in visible region. Mo doping was shown to be an efficient method for degradation of methylene blue under visible light, especially under solar light. When the calcination temperature was 550°C and the Mo doping amount was 2.0%, the Mo-doped TiO2 sample exhibited the highest photocatalytic activity.

The Photocatalytic Activity and Compact Layer Characteristics of TiO2 Films Prepared Using Radio Frequency Magnetron Sputtering

Directory of Open Access Journals (Sweden)

H. C. Chang

2014-01-01

Full Text Available TiO2 compact layers are used in dye-sensitized solar cells (DSSCs to prevent charge recombination between the electrolyte and the transparent conductive substrate (indium tin oxide, ITO; fluorine-doped tin oxide, FTO. Thin TiO2 compact layers are deposited onto ITO/glass by means of radio frequency (rf magnetron sputtering, using deposition parameters that ensure greater photocatalytic activity and increased DSSC conversion efficiency. The photoinduced decomposition of methylene blue (MB and the photoinduced hydrophilicity of the TiO2 thin films are also investigated. The photocatalytic performance characteristics for the deposition of TiO2 films are improved by using the Grey-Taguchi method. The average transmittance in the visible region exceeds 85% for all samples. The XRD patterns of the TiO2 films, for sol-gel with spin coating of porous TiO2/TiO2 compact/ITO/glass, show a good crystalline structure. In contrast, without the TiO2 compact layer (only porous TiO2, the peak intensity of the anatase (101 plane in the XRD patterns for the TiO2 film has a lower value, which demonstrates inferior crystalline quality. With a TiO2 compact layer to prevent charge recombination, a higher short-circuit current density is obtained. The DSSC with the FTO/glass and Pt counter electrode demonstrates the energy conversion efficiency increased.

Photoelectrolchemical performance of PbS/CdS quantum dots co-sensitized TiO2 nanosheets array film photoelectrodes

International Nuclear Information System (INIS)

Yao, Huizhen; Li, Xue; Liu, Li; Niu, Jiasheng; Ding, Dong; Mu, Yannan; Su, Pengyu; Wang, Guangxia; Fu, Wuyou; Yang, Haibin

2015-01-01

Herein, PbS/CdS quantum dots (QDs) co-sensitized titanium dioxide nanosheets array (TiO 2 NSs) films were reported for the first time. The TiO 2 NSs films exposed {001} facets were vertically grown on transparent conductive fluorine-doped tin oxide (FTO) glass substrates by a facile hydrothermal method. The PbS/CdS QDs were assembled on TiO 2 NSs photoelectrode by successive ionic layer adsorption and reaction (SILAR). The X-ray diffraction pattern (XRD) and transmission electron microscopy (TEM) verified that QDs with a diameter less than 20 nm were uniformly anchored on the surface of the TiO 2 NSs films. The QDs co-sensitization can significantly extend the absorption range and increase the absorption property of the photoelectrode by UV–vis absorption spectra. The optimal photoelectrolchemical (PEC) performance of PbS/CdS QDs co-sensitization TiO 2 NSs was with photocurrent density of 6.12 mA cm −2 under an illumination of AM 1.5 G, indicating the TiO 2 NSs films co-sensitized by PbS/CdS QDs have potential applications in solar cells. - Highlights: • TiO 2 nanosheets films were fabricated by a simple hydrothermal. • TiO 2 nanosheets film exposed high energy facets was with gaps. • PbS/CdS co-sensitized TiO 2 nanosheets film was obtained for the first time. • Photocurrent intensity of the novel photoelectrode increased to 6.12 mA cm −2

Nanocrystalline Pt-doped TiO2 thin films prepared by spray pyrolysis ...

Indian Academy of Sciences (India)

Administrator

Spray pyrolysis techniques; TiO2 thin films; hydrogen gas response. 1. Introduction ... tion is necessary during the production, storage and use of hydrogen. It is also ..... ient, and 'green': it may be used to large scale industrial application for ...

Effect of substrate roughness and working pressure on photocatalyst of N-doped TiOx films prepared by reactive sputtering with air

International Nuclear Information System (INIS)

Lee, Seon-Hong; Yamasue, Eiji; Okumura, Hideyuki; Ishihara, Keiichi N.

2015-01-01

Highlights: • Effect of substrate roughness and working pressure on the physical properties and the photocatalytic properties of the N-doped TiO x films are investigated. • Surface roughness of glass substrate has little influence on the film properties, but significant influence on the photocatalytic ability. • Working pressure has little influence on the produced phases and the atomic bonding configurations, but significant influence on the atomic concentration of the N-doped TiO x film. • High photocatalysis of N-doped TiO x film requires the permissible range of the N doping concentration which shows the interstitial complex N doping states in TiO 2 . - Abstract: N-doped TiO x films on the glass substrate were prepared by radio-frequency (RF) magnetron reactive sputtering of Ti target in a mixed gas of argon and dry air. The effect of substrate roughness and working pressure on the physical properties and the photocatalytic properties of the N-doped TiO x films was investigated. The surface roughness of glass substrate has little influence on the film properties such as produced phases, lattice parameters, introduced nitrogen contents, and atomic bonding configurations, but significant influence on the surface roughness of film resulting in the variation of the photocatalytic ability. The working pressure has little influence on the produced phases and the atomic bonding configurations, but significant influence on the atomic concentration of the N-doped TiO x film, resulting in the large variation of optical, structural, and photocatalytic properties. It is suggested that the high photocatalysis of N-doped TiO x film requires a certain range of the N doping concentration which shows the interstitial complex N doping states in TiO 2

Optical spectroscopy of rare earth ion-doped TiO2 nanophosphors.

Science.gov (United States)

Chen, Xueyuan; Luo, Wenqin

2010-03-01

Trivalent rare-earth (RE3+) ion-doped TiO2 nanophosphors belong to one kind of novel optical materials and have attracted increasing attention. The luminescence properties of different RE3+ ions in various TiO2 nanomaterials have been reviewed. Much attention is paid to our recent progresses on the luminescence properties of RE3+ (RE = Eu, Er, Sm, Nd) ions in anatase TiO2 nanoparticles prepared by a sol-gel-solvothermal method. Using Eu3+ as a sensitive optical probe, three significantly different luminescence centers of Eu3+ in TiO2 nanoparticles were detected by means of site-selective spectroscopy at 10 K. Based on the crystal-field (CF) splitting of Eu3+ at each site, C2v and D2 symmetries were proposed for Eu3+ incorporated at two lattice sites. A structural model for the formation of multiple sites was proposed based on the optical behaviors of Eu3+ at different sites. Similar multi-site luminescence was observed in Sm(3+)- or Nd(3+)-doped TiO2 nanoparticles. In Eu(3+)-doped TiO2 nanoparticles, only weak energy transfer from the TiO2 host to the Eu3+ ions was observed at 10 K due to the mismatch of energy between the TiO2 band-gap and the Eu3+ excited states. On the contrary, efficient host-sensitized luminescences were realized in Sm(3+)- or Nd(3+)-doped anatase TiO2 nanoparticles due to the match of energy between TiO2 band-gap and the Sm3+ and Nd3+ excited states. The excitation spectra of both Sm(3+)- and Nd(3+)-doped samples exhibit a dominant broad peak centered at approximately 340 nm, which is associated with the band-gap of TiO2, indicating that sensitized emission is much more efficient than direct excitation of the Sm3+ and Nd3+ ions. Single lattice site emission of Er3+ in TiO2 nanocrystals can be achieved by modifying the experimental conditions. Upon excitation by a Ti: sapphire laser at 978 nm, intense green upconverted luminescence was observed. The characteristic emission of Er3+ ions was obtained both in the ultraviolet-visible (UV-vis) and

Photocatalytic and microwave absorbing properties of polypyrrole/Fe-doped TiO2 composite by in situ polymerization method

International Nuclear Information System (INIS)

Li Qiaoling; Zhang Cunrui; Li Jianqiang

2011-01-01

Research highlights: → Polypyrrole/Fe-doped TiO 2 composite is prepared by in situ polymerization of pyrrole on the Fe-doped TiO 2 template. → The Fe-doped TiO 2 microbelts are prepared by sol-gel method using the absorbent cotton template for the first time. → Then the Fe-doped TiO 2 microbelts are used as template for the preparation of polypyrrole/Fe-doped TiO 2 composites. → The structure, morphology and properties of the composites are characterized with scanning electron microscope (SEM), IR, Net-work Analyzer. → A possible formation mechanism of Fe-doped TiO 2 microbelts and polypyrrole/Fe-doped TiO 2 composites has been proposed. → The effect of the mol ratio of pyrrole/Fe-doped TiO 2 on the photocatalysis properties and microwave loss properties of the composites is investigated. - Abstract: The Fe-doped TiO 2 microbelts were prepared by sol-gel method using the absorbent cotton template for the first time. Then the Fe-doped TiO 2 microbelts were used as templates for the preparation of polypyrrole/Fe-doped TiO 2 composites. Polypyrrole/Fe-doped TiO 2 composites were prepared by in situ polymerization of pyrrole on the Fe-doped TiO 2 template. The structure, morphology and properties of the composites were characterized with scanning electron microscope (SEM), FTIR, Net-work Analyzer. The possible formation mechanisms of Fe-doped TiO 2 microbelts and polypyrrole/Fe-doped TiO 2 composites have been proposed. The effect of the molar ratio of pyrrole/Fe-doped TiO 2 on the photocatalytic properties and microwave loss properties of the composites was investigated.

Copper doping enhanced the oxidative stress-mediated cytotoxicity of TiO2 nanoparticles in A549 cells.

Science.gov (United States)

Ahmad, J; Siddiqui, M A; Akhtar, M J; Alhadlaq, H A; Alshamsan, A; Khan, S T; Wahab, R; Al-Khedhairy, A A; Al-Salim, A; Musarrat, J; Saquib, Q; Fareed, M; Ahamed, M

2018-05-01

Physicochemical properties of titanium dioxide nanoparticles (TiO 2 NPs) can be tuned by doping with metals or nonmetals. Copper (Cu) doping improved the photocatalytic behavior of TiO 2 NPs that can be applied in various fields such as environmental remediation and nanomedicine. However, interaction of Cu-doped TiO 2 NPs with human cells is scarce. This study was designed to explore the role of Cu doping in cytotoxic response of TiO 2 NPs in human lung epithelial (A549) cells. Characterization data demonstrated the presence of both TiO 2 and Cu in Cu-doped TiO 2 NPs with high-quality lattice fringes without any distortion. The size of Cu-doped TiO 2 NPs (24 nm) was lower than pure TiO 2 NPs (30 nm). Biological results showed that both pure and Cu-doped TiO 2 NPs induced cytotoxicity and oxidative stress in a dose-dependent manner. Low mitochondrial membrane potential and higher caspase-3 enzyme (apoptotic markers) activity were also observed in A549 cells exposed to pure and Cu-doped TiO 2 NPs. We further observed that cytotoxicity caused by Cu-doped TiO 2 NPs was higher than pure TiO 2 NPs. Moreover, antioxidant N-acetyl cysteine effectively prevented the reactive oxygen species generation, glutathione depletion, and cell viability reduction caused by Cu-doped TiO 2 NPs. This is the first report showing that Cu-doped TiO 2 NPs induced cytotoxicity and oxidative stress in A549 cells. This study warranted further research to explore the role of Cu doping in toxicity mechanisms of TiO 2 NPs.

Hydrothermal synthesis of Fe-doped TiO2 nanostructure photocatalyst

International Nuclear Information System (INIS)

Nguyen, Van Nghia; Nguyen, Ngoc Khoa Truong; Nguyen, Phi Hung

2011-01-01

Fe-doped TiO 2 catalyst was prepared by the hydrothermal method. The resulting nanopowders were characterized by x-ray diffraction, transmission electron microscopy and Raman and UV-visible spectroscopies. The photocatalytic activity of the Fe-doped TiO 2 was tested by decomposition of methylene orange with a concentration of 10 mg l −1 in aqueous solution. The obtained results showed that methylene orange was significantly degraded after irradiation for 90 min under a halogen lamp and sunlight. The doping effect on the photocatalytic activity of the iron-doped catalyst samples are discussed

Tuning the morphology, stability and photocatalytic activity of TiO2 nanocrystal colloids by tungsten doping

International Nuclear Information System (INIS)

Xu, Haiping; Liao, Jianhua; Yuan, Shuai; Zhao, Yin; Zhang, Meihong; Wang, Zhuyi; Shi, Liyi

2014-01-01

Graphical abstract: - Highlights: • W 6+ -doped TiO 2 nanocrystal colloids were prepared by hydrothermal methods. • The properties of TiO 2 nanocrystal colloids can be tuned by tungsten doping. • W 6+ -doped TiO 2 nanocrystal colloids show higher stability and dispersity. • W 6+ -doped TiO 2 nanocrystal colloids show higher photocatalytic activity. - Abstract: The effects of tungsten doping on the morphology, stability and photocatalytic activity of TiO 2 nanocrystal colloids were investigated. The nanostructure, chemical state of Ti, W, O, and the properties of tungsten doped TiO 2 samples were investigated carefully by TEM, XRD, XPS, UV–vis, PL and photocatalytic degradation experiments. And the structure–activity relationship was discussed according to the analysis and measurement results. The analysis results reveal that the morphology, zeta potential and photocatalytic activity of TiO 2 nanocrystals can be easily tuned by changing the tungsten doping concentration. The tungsten doped TiO 2 colloid combines the characters of high dispersity and high photocatalytic activity

Synthesis and characterization of erbium-doped SiO2-TiO2 thin films prepared by sol-gel and dip-coating techniques onto commercial glass substrates as a route for obtaining active GRadient-INdex materials

International Nuclear Information System (INIS)

Gómez-Varela, Ana I.; Castro, Yolanda; Durán, Alicia; De Beule, Pieter A.A.; Flores-Arias, María T.; Bao-Varela, Carmen

2015-01-01

In this work, SiO 2 -TiO 2 films doped with erbium were prepared by dip-coating sol-gel process onto commercial glass substrates. The surface morphology of the films was characterized using atomic force microscopy, while thickness, refractive index, extinction coefficient and porosity of the films were determined by ellipsometric measurements in a wavelength region of 400-1000 nm. Optical constants and porosity were found to vary with erbium concentration. The proof of principle presented in this paper is applicable to systems of different nature by tailoring the sol-gel precursors in such a way that active GRadient-INdex media described by a complex, parabolic-like refractive index distribution for beam shaping purposes is obtained. - Highlights: • Sol-gel route for preparation of active GRadient-INdex materials is proposed. • SiO 2 -TiO 2 films doped with erbium were prepared by dipping onto commercial glasses. • Morphological and optical characterization of the samples was performed. • Optical constants and porosity were found to vary with erbium concentration. • Refractive index diminishes with dopant content; the contrary occurs for porosity

Transparent TiO2 nanowire networks via wet corrosion of Ti thin films for dye-sensitized solar cells

Science.gov (United States)

Shin, Eunhye; Jin, Saera; Hong, Jongin

2017-09-01

Transparent TiO2 nanowire networks were prepared by corrosion of Ti thin films on F-doped SnO2 glass substrates in an alkaline (potassium hydroxide: KOH) solution. The formation of the porous TiO2 nanostructures from the Ti thin films was thoroughly investigated. Dye-sensitized solar cells with a photoanode of 1.2-μm-thick nanowire networks exhibit an average optical transmittance of 40% in the visible light region and a power conversion efficiency of 1.0% under one sun illumination.

Enhancement of tributyltin degradation under natural light by N-doped TiO2 photocatalyst

International Nuclear Information System (INIS)

Bangkedphol, S.; Keenan, H.E.; Davidson, C.M.; Sakultantimetha, A.; Sirisaksoontorn, W.; Songsasen, A.

2010-01-01

Photo-degradation of tributyltin (TBT) has been enhanced by TiO 2 nanoparticles doped with nitrogen (N-doped TiO 2 ). The N-doped catalyst was prepared by a sol-gel reaction of titanium (IV) tetraisopropoxide with 25% ammonia solution and calcined at various temperatures from 300 to 600 deg. C. X-ray diffraction results showed that N-doped TiO 2 remained amorphous at 300 deg. C. At 400 deg. C the anatase phase occurred then transformed to the rutile phase at 600 deg. C. The crystallite size calculated from Scherrer's equation was in the range of 16-51 nm which depended on the calcination temperature. N-doped TiO 2 calcined at 400 deg. C which contained 0.054% nitrogen, demonstrated the highest photocatalytic degradation of TBT at 28% in 3 h under natural light when compared with undoped TiO 2 and commercial photocatalyst, P25-TiO 2 which gave 14.8 and 18% conversion, respectively.

Effect of zinc doping on the bandgap and photoluminescence of Zn2+-doped TiO2 nanowires

Science.gov (United States)

Loan, Trinh Thi; Huong, Vu Hoang; Tham, Vu Thi; Long, Nguyen Ngoc

2018-03-01

This study was focused on the effect of Zn2+ dopant concentration on the absorption edge and photoluminescence of anatase TiO2 nanowires synthesized by hydrothermal technique. For the undoped anatase TiO2 nanowires, the indirect band gap of 3.26 eV and the direct band gap of 3.58 eV are assigned to the indirect Γ3 → X1b and direct X2b → X1b transitions, respectively. The Zn2+-doping makes the absorption edge of TiO2:Zn2+ nanowires shift towards the lower energy side (red shift). On the other hand, the replacing Ti4+ ions with Zn2+ ions creates oxygen vacancies (VO) and shallow defects associated with VO. Just these defects are responsible for the enhanced luminescence of Zn2+-doped TiO2 nanowires.

Hydrogen incorporation by plasma treatment gives mesoporous black TiO ₂ thin films with visible photoelectrochemical water oxidation activity

Energy Technology Data Exchange (ETDEWEB)

Islam, Syed Z.; Reed, Allen; Nagpure, Suraj; Wanninayake, Namal; Browning, James F.; Strzalka, Joseph; Kim, Doo Young; Rankin, Stephen E.

2018-05-01

In this work, we use neutron reflectometry (NR) to investigate the roles of hydrogen in plasma treated hydrogen doped mesoporous black titania thin films in their visible light absorption and enhanced photoactivity for water oxidation. The cubic ordered mesoporous TiO2 thin films are prepared by a surfactant-templated sol-gel method and are treated with hydrogen plasma, an approach hypothesized to capitalize on the high degree of disorder in the material and the high energy of the plasma species to achieve efficient hydrogen doping. UV-vis absorbance spectra indicate that H2 plasma treatment makes TiO2 films black, with broad-spectrum enhancement of visible light absorption, and XPS analysis shows peak for Ti3+ state in treated films. The presence of hydrogen in black mesoporous titania (H-TiO2) films is confirmed by the scattering length density (SLD) profiles obtained from neutron reflectometry measurements. The H-TiO2 shows ca. 28 times and 8 times higher photocurrent for photoelectrochemical water oxidation compared to undoped TiO2 films under UV (365 nm) and blue (455 nm) LED irradiation, respectively. These findings provide the first direct evidence that the dramatic change in visible light absorbance of H-treated black TiO2 is accompanied by significant hydrogen uptake and not just Ti3+ generation or surface disordering.

Photocatalytic activity of TiO2 doped with boron and vanadium

International Nuclear Information System (INIS)

Bettinelli, M.; Dallacasa, V.; Falcomer, D.; Fornasiero, P.; Gombac, V.; Montini, T.; Romano, L.; Speghini, A.

2007-01-01

Boron (B)- and vanadium (V)-doped TiO 2 photocatalysts were synthesized using modified sol-gel reaction processes and characterized by X-ray diffraction (XRD), Raman spectroscopy and N 2 physisorption (BET). The photocatalytic activities were evaluated by monitoring the degradation of methylene blue (MB). The results showed that the materials possess high surface area. The addition of B favored the transformation of anatase to rutile, while in the presence of V, anatase was the only phase detected. The MB degradation on V-doped TiO 2 was significantly affected by the preparation method. In fact while the presence of V in the bulk did not influence strongly the photoreactivity under visible irradiation, an increase of surface V doping lead to improved photodegradation of MB. The degradation of MB dye indicated that the photocatalytic activities of TiO 2 increased as the boron doping increased, with high conversion efficiency for 9 mol% B doping

Polythiophene thin films electrochemically deposited on sol-gel based TiO2 for photovoltaic applications

International Nuclear Information System (INIS)

Valaski, R.; Yamamoto, N.A.D.; Canestraro, C.D.; Micaroni, L.; Mello, R.M.Q.; Quirino, W.G.; Legani, C.; Achete, C.A.; Roman, L.S.; Cremona, M.

2010-01-01

In this work, the influence of titanium dioxide (TiO 2 ) thin films on the efficiency of organic photovoltaic devices based on electrochemically synthesized polythiophene (PT) was investigated. TiO 2 films were produced by sol-gel methods with controlled thickness. The best TiO 2 annealing condition was determined through the investigation of the temperature influence on the electron charge mobility and resistivity in a range between 723 K and 923 K. The PT films were produced by chronoamperometric method in a 3-electrode cell under a controlled atmosphere. High quality PT films were produced onto 40 nm thick TiO 2 layer previously deposited onto fluorine doped tin oxide (FTO) substrate. The morphology of PT films grown on both substrates and its strong influence on the device performance and PT minimum thickness were also investigated. The maximum external quantum efficiency (IPCE) reached was 9% under monochromatic irradiation (λ = 610 nm; 1 W/m 2 ) that is three orders of magnitude higher than that presented by PT-homolayer devices with similar PT thickness. In addition, the open-circuit voltage (V oc ) was about 700 mV and the short-circuit current density (J sc ) was 0.03 A/m 2 (λ = 610 nm; 7 W/m 2 ). However, as for the PT-homolayer also the TiO 2 /PT based devices are characterized by antibatic response when illuminated through FTO. Finally, the Fill Factor (FF) of these devices is low (25%), indicating that the series resistance (R s ), which is strongly dependent of the PT thickness, is too large. This large R s value is compensated by TiO 2 /PT interface morphology and by FTO/TiO 2 and TiO 2 /PT interface phenomena producing preferential paths in which the internal electrical field is higher, improving the device efficiency.

Revelation of rutile phase by Raman scattering for enhanced photoelectrochemical performance of hydrothermally-grown anatase TiO2 film

Science.gov (United States)

Cho, Hsun-Wei; Liao, Kuo-Lun; Yang, Jih-Sheng; Wu, Jih-Jen

2018-05-01

Photoelectrochemical (PEC) performances of the anatase TiO2 films hydrothermally grown on the seeded fluorine-doped tin oxide (FTO) substrates are examined in this work. Structural characterizations of the TiO2 films were conducted using Raman scattering spectroscopy. Although there is no obvious rutile peak appearing, an asymmetrical peak centered at ∼399 cm-1 was observed in the Raman spectra of the TiO2 films deposited either on the low-temperature-formed seed layers or with low concentrations of Ti precursor. The asymmetrical Raman shift can be deconvoluted into the B1g mode of anatase and Eg mode of rutile TiO2 peaks centered at ∼399 cm-1 and ∼447 cm-1, respectively. Therefore, a minute quantity of rutile phase was inspected in the anatase film using Raman scattering spectroscopy. With the same light harvesting ability, we found that the PEC performance of the anatase TiO2 film was significantly enhanced as the minute quantity of rutile phase existing in the film. It is ascribed to the formation of the anatase/rutile heterojunction which is beneficial to the charge separation in the photoanode.

Y-doping TiO2 nanorod arrays for efficient perovskite solar cells

Science.gov (United States)

Deng, Xinlian; Wang, Yanqing; Cui, Zhendong; Li, Long; Shi, Chengwu

2018-05-01

To improve the electron transportation in TiO2 nanorod arrays and charge separation in the interface of TiO2/perovskite, Y-doping TiO2 nanorod arrays with the length of 200 nm, diameter of 11 nm and areal density of 1050 μm-2 were successfully prepared by the hydrothermal method and the influence of Y/Ti molar ratios of 0%, 3%, 5% in the hydrothermal grown solutions on the growth of TiO2 nanorod arrays was investigated. The results revealed that the appropriate Y/Ti molar ratios can increase the areal density of the corresponding TiO2 nanorod arrays and improve the charge separation in the interface of the TiO2/perovskite. The Y-doping TiO2 nanorod array perovskite solar cells with the Y/Ti molar ratio of 3% exhibited a photoelectric conversion efficiency (PCE) of 18.11% along with an open-circuit voltage (Voc) of 1.06 V, short-circuit photocurrent density (Jsc) of 22.50 mA cm-2 and fill factor (FF) of 76.16%, while the un-doping TiO2 nanorod array perovskite solar cells gave a PCE of 16.42% along with Voc of 1.04 V, Jsc of 21.66 mA cm-2 and FF of 72.97%.

Photo-induced hydrophilicity of TiO2-xNx thin films on PET plates

International Nuclear Information System (INIS)

Chou, H.-Y.; Lee, E.-K.; You, J.-W.; Yu, S.-S.

2007-01-01

TiO 2-x N x thin films were deposited on PET (polyethylene terephthalate) plates by sputtering a TiN target in a N 2 /O 2 plasma and without heating. X-ray photoemission spectroscopy (XPS) was used to investigate the N 1s, Ti 2p core levels and the nitrogen composition in the TiO 2-x N x films. The results indicate that Ti-O-N bonds are formed in the thin films. Two nitrogen states, substitution and interstitial nitrogen atoms, were attributed to peaks at 396 and 399 eV, respectively. It was observed that the nitrogen atoms occupy both the substitutive and interstitial sites in respective of the nitrogen content in the thin films. UV-VIS absorption spectroscopy of PET coated thin films shows a significant shift of the absorption edge to lower energy in the visible-light region. UV and visible-light irradiation are used to activate PET coated thin films for the development of hydrophilicity. The photo-induced surface wettability conversion reaction of the thin films has been investigated by means of water contact angle measurement. PET plates coated with TiO 2-x N x thin films are found to exhibit lower water contact angle than non-coated plates when the surface is illuminated with UV and visible light. The effects of nitrogen doping on photo-generated hydrophilicity of the thin films are investigated in this work

Improved visible-light photocatalytic activity of TiO2 co-doped with copper and iodine

Science.gov (United States)

Dorraj, Masoumeh; Goh, Boon Tong; Sairi, Nor Asrina; Woi, Pei Meng; Basirun, Wan Jefrey

2018-05-01

Cu-I-co-doped TiO2 photocatalysts active to visible light absorption were prepared by hydrothermal method and calcined at various temperatures (350 °C, 450 °C, and 550 °C). The co-doped powders at 350 °C displayed the highest experimental Brunauer-Emmett-Teller surface area and lowest photoluminescence intensity, which demonstrated that a decrease in electron-hole recombination process. The synthesis of co-doped TiO2 was performed at this optimized temperature. In the co-doped sample, the Cu2+ doped TiO2 lattice created a major "red-shift" in the absorption edge due to the presence of the 3d Cu states, whereas the amount of red-shift from the I5+ doping in the TiO2 lattice was minor. Interestingly, the presence of Cu2+ species also boosted the reduction of I5+ ions to the lower multi-valance state I- in the TiO2 lattice by trapping the photogenerated electrons, which resulted in effective separation of the photogenerated charges. The Cu-I-co-doped TiO2 was able to degrade methyl orange dye under visible-light irradiation with improved photocatalytic activity compared with the single metal-doped TiO2 and pure TiO2 because of the strong visible light absorption and effective separation of photogenerated charges caused by the synergistic effects of Cu and I co-dopants.

Ce-doping effects on electronic structures of Ba0.5Sr0.5TiO3 thin film

International Nuclear Information System (INIS)

Wang, S Y; Cheng, B L; Wang, Can; Button, T W; Dai, S Y; Jin, K J; Lu, H B; Zhou, Y L; Chen, Z H; Yang, G Z

2006-01-01

In order to clarify the basic reason why Ce doping can dramatically decrease the leakage current in Ba 0.5 Sr 0.5 TiO 3 (BST) as reported in our previous work (Wang et al 2005 J. Phys. D: Appl. Phys. 38 2253), we have employed x-ray photoelectron spectroscopy (XPS) and the optical transmittance technique to study the electronic structure of undoped and 1.0 at% Ce-doped BST (CeBST) films fabricated by pulsed laser deposition. XPS results show that Ce doping has a strong influence on the valence band and core levels of BST films, and that the Fermi level is lowered by about 0.35 eV by Ce doping. Optical transmittance measurements demonstrate that the energy gap is expanded with Ce doping. These Ce-doping effects can induce an increase in the barrier height for the thermionic emission and eventually reduce leakage current in CeBST thin films

Influence of the Porosity of the TiO2 Film on the Performance of the Perovskite Solar Cell

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Xiaodan Sun

2017-01-01

Full Text Available The structure of mesoporous TiO2 (mp-TiO2 films is crucial to the performance of mesoporous perovskite solar cells (PSCs. In this study, we fabricated highly porous mp-TiO2 films by doping polystyrene (PS spheres in TiO2 paste. The composition of the perovskite films was effectively improved by modifying the mass fraction of the PS spheres in the TiO2 paste. Due to the high porosity of the mp-TiO2 film, PbI2 and CH3NH3I could sufficiently infiltrate into the network of the mp-TiO2 film, which ensured a more complete transformation to CH3NH3PbI3. The surface morphology of the mp-TiO2 film and the photoelectric performance of the perovskite solar cells were investigated. The results showed that an increase in the porosity of the mp-TiO2 film resulted in an improvement in the performance of the PSCs. The best device with the optimized mass fraction of 1.0 wt% PS in TiO2 paste exhibited an efficiency of 12.69%, which is 25% higher than the efficiency of the PSCs without PS spheres.

TiO2 Nanotubes on Transparent Substrates: Control of Film Microstructure and Photoelectrochemical Water Splitting Performance

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Matus Zelny

2018-01-01

Full Text Available Transfer of semiconductor thin films on transparent and or flexible substrates is a highly desirable process to enable photonic, catalytic, and sensing technologies. A promising approach to fabricate nanostructured TiO2 films on transparent substrates is self-ordering by anodizing of thin metal films on fluorine-doped tin oxide (FTO. Here, we report pulsed direct current (DC magnetron sputtering for the deposition of titanium thin films on conductive glass substrates at temperatures ranging from room temperature to 450 °C. We describe in detail the influence that deposition temperature has on mechanical, adhesion and microstructural properties of titanium film, as well as on the corresponding TiO2 nanotube array obtained after anodization and annealing. Finally, we measure the photoelectrochemical water splitting activity of different TiO2 nanotube samples showing that the film deposited at 150 °C has much higher activity correlating well with the lower crystallite size and the higher degree of self-organization observed in comparison with the nanotubes obtained at different temperatures. Importantly, the film showing higher water splitting activity does not have the best adhesion on glass substrate, highlighting an important trade-off for future optimization.

Effect of Graphite Doped TiO_2 Nanoparticles on Smoke Degradation

International Nuclear Information System (INIS)

Roshasnorlyza Hazan; Mohamad Shahrizal Md Zain; Natrah Syafiqah Rosli

2016-01-01

Secondhand smoke affects in the same way as regular smoker. The best solution is to purify the air efficiently and effectively. In this study, we were successfully doped TiO_2 nanoparticle with graphite to accelerate the degradation of cigarette smoke. The graphite doped and undoped TiO_2 nanoparticles were prepared from synthetic rutile using alkaline fusion method and their photo catalytic activity were investigated under visible light irradiation. The photo catalytic activity of the TiO_2 nanoparticles was analyzed in terms of their particle size analysis, crystallization and optical band gap. TiO_2 nanoparticle act as photo catalyzer by utilization of light energy to excite electron-hole pairs in smoke degradation processes. With the aided from graphite in TiO_2 nanoparticles, the smoke degradation was accelerate up to 44.4 %. In this case, graphite helps to reduce optical band gap of TiO_2 nanoparticle, thus increasing excitation of electron from valence band to conduction band. (author)

Effects of donor doping and acceptor doping on rutile TiO2 particles for photocatalytic O2 evolution by water oxidation

Science.gov (United States)

Amano, Fumiaki; Tosaki, Ryosuke; Sato, Kyosuke; Higuchi, Yamato

2018-02-01

Crystalline defects of photocatalyst particles may be considered to be the recombination center of photoexcited electrons and holes. In this study, we investigated the photocatalytic activity of cation-doped rutile TiO2 photocatalysts for O2 evolution from an aqueous silver nitrate solution under ultraviolet light irradiation. The photocatalytic activity of rutile TiO2 was enhanced by donor doping of Ta5+ and Nb5+ with a valence higher than that of Ti4+, regardless of increased density of electrons and Ti3+ species (an electron trapped in Ti4+ sites). Conversely, acceptor doping of lower valence cations such as In3+ and Ga3+ decreased photocatalytic activity for O2 evolution by water oxidation. The doping of equal valence cations such as Sn4+ and Ge4+ hardly changed the activity of non-doped TiO2. This study demonstrates that Ti3+ species, which is a crystalline defect, enhanced the photocatalytic activity of semiconductor oxides, for example rutile TiO2 with large crystalline size.

Synthesis of Nd3+doped TiO2 nanoparticles and Its Optical Behaviour

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Ezhil Arasi S.

2017-04-01

Full Text Available Pure and Rare earth ion doped TiO2 nanoparticles were synthesized by Sol-gel method. The synthesized TiO2 nanoparticles were characterized by X-ray diffraction, Raman spectroscopy, UV–Vis spectroscopy and photoluminescence emission spectra. From the UV-visible measurement, the absorption edge of Nd3+-TiO2 was shifted to a higher wavelength side with decreasing band gap. Photoluminescence emission studies reveal the energy transfer mechanism of Nd3+ doped TiO2 nanoparticles explain.

Photocatalytic degradation of Rhodamine B dye using Fe doped TiO2 nanocomposites

Science.gov (United States)

Barkhade, Tejal; Banerjee, Indrani

2018-05-01

The unique properties of titanium dioxide (TiO2) such as high photo catalytic activity, high chemical stability and low toxicity have made it a suitable photocatalyst in recent decades. The effect of modification of TiO2 with doping of iron on its characteristics and photo catalytic efficiency was studied. The change in band gap energy of TiO2 nanoparticles after doping with Fe has been studied. Significant enhancement in photo catalytic property of TiO2 after Fe doping under light exposure conditions has been investigated. Acute exposure to non-biodegradable Rhodamine B resulted in many health problems like burning of eyes, skin irritation, nasal burning, and chest pain etc. Therefore, degradation of this dye is needed to save environment and animals. Considering the similar radius of Fe3+ and Ti4+ ions (respectively 0.64 Å and 0.68 Å), titanium position in the lattice of TiO2 can be replaced by iron cations easily. The undoped and Fe doped TiO2 nano composites were synthesized by sol-gel method, in which 1.0M% of Fe was doped with TiO2 and then the samples were characterized by using FE-SEM, UV-Visible diffuse spectroscopy, Raman Spectroscopy, and FTIR. Photo catalytic degradation of Rhodamine B dye experiment was carried out in visible light range. After 90 min time duration pink colour of dye turned colourless, indicating significant degradation rate with time.

Influence of VB group doped TiO2 on photovoltaic performance of dye-sensitized solar cells

International Nuclear Information System (INIS)

Liu, Jia; Duan, Yandong; Zhou, Xiaowen; Lin, Yuan

2013-01-01

Dye-sensitized solar cell with V B group (vanadium (V), niobium (Nb) and tantalum (Ta)) doped TiO 2 prepared by hydrothermal method shows a higher photovoltaic efficiency compared with the undoped TiO 2 . All the V B doping shift the flat band potential positively and increase the doping density which is investigated by Mott–Schottky plot. The positive shift of flat band potential improves the driving force of injecting electron from the LUMO of dye to the conduction band of TiO 2 and the photocurrent. On the other hand, the increase of doping density accelerates transfer rate of electrons in TiO 2 than the un-doped, which is confirmed by intensity-modulated photocurrent. V-, Nb-, Ta-doped TiO 2 exhibited photovoltaic performance with 7.80%, 8.33%, 8.18%, respectively, compared with that of the cells based on pure TiO 2 (7.42%).

Room temperature one-step synthesis of microarrays of N-doped flower-like anatase TiO2 composed of well-defined multilayer nanoflakes by Ti anodization

Science.gov (United States)

Wang, Chenglin; Wang, Mengye; Xie, Kunpeng; Wu, Qi; Sun, Lan; Lin, Zhiqun; Lin, Changjian

2011-07-01

Microarrays of N-doped flower-like TiO2 composed of well-defined multilayer nanoflakes were synthesized at room temperature by electrochemical anodization of Ti in NH4F aqueous solution. The TiO2 flowers were of good anatase crystallinity. The effects of anodizing time, applied voltage and NH4F concentration on the flower-like morphology were systematically examined. It was found that the morphologies of the anodized Ti were related to the anodizing time and NH4F concentration. The size and density of the TiO2 flowers could be tuned by changing the applied voltage. The obtained N-doped flower-like TiO2 microarrays exhibited intense absorption in wavelengths ranging from 320 to 800 nm. Under both UV and visible light irradiation, the photocatalytic activity of the N-doped flower-like TiO2 microarrays in the oxidation of methyl orange showed a significant increase compared with that of commercial P25 TiO2 film.

XRD analysis of undoped and Fe doped TiO2 nanoparticles by Williamson Hall method

International Nuclear Information System (INIS)

Bharti, Bandna; Barman, P. B.; Kumar, Rajesh

2015-01-01

Undoped and Fe doped titanium dioxide (TiO 2 ) nanoparticles were synthesized by sol-gel method at room temperature. The synthesized samples were annealed at 500°C. For structural analysis, the prepared samples were characterized by X-ray diffraction (XRD). The crystallite size of TiO 2 and Fe doped TiO 2 nanoparticles were calculated by Scherer’s formula, and was found to be 15 nm and 11 nm, respectively. Reduction in crystallite size of TiO 2 with Fe doping was observed. The anatase phase of Fe-doped TiO 2 nanoparticles was also confirmed by X-ray diffraction. By using Williamson-Hall method, lattice strain and crystallite size were also calculated. Williamson–Hall plot indicates the presence of compressive strain for TiO 2 and tensile strain for Fe-TiO 2 nanoparticles annealed at 500°C

Dielectric properties of BaMg1/3Nb2/3O3 doped Ba0.45Sr0.55Tio3 thin films for tunable microwave applications

Science.gov (United States)

Alema, Fikadu; Pokhodnya, Konstantin

2015-11-01

Ba(Mg1/3Nb2/3)O3 (BMN) doped and undoped Ba0.45Sr0.55TiO3 (BST) thin films were deposited via radio frequency magnetron sputtering on Pt/TiO2/SiO2/Al2O3 substrates. The surface morphology and chemical state analyses of the films have shown that the BMN doped BST film has a smoother surface with reduced oxygen vacancy, resulting in an improved insulating properties of the BST film. Dielectric tunability, loss, and leakage current (LC) of the undoped and BMN doped BST thin films were studied. The BMN dopant has remarkably reduced the dielectric loss (˜38%) with no significant effect on the tunability of the BST film, leading to an increase in figure of merit (FOM). This is attributed to the opposing behavior of large Mg2+ whose detrimental effect on tunability is partially compensated by small Nb5+ as the two substitute Ti4+ in the BST. The coupling between MgTi″ and VO•• charged defects suppresses the dielectric loss in the film by cutting electrons from hopping between Ti ions. The LC of the films was investigated in the temperature range of 300-450K. A reduced LC measured for the BMN doped BST film was correlated to the formation of defect dipoles from MgTi″, VO•• and NbTi• charged defects. The carrier transport properties of the films were analyzed in light of Schottky thermionic emission (SE) and Poole-Frenkel (PF) emission mechanisms. The result indicated that while the carrier transport mechanism in the undoped film is interface limited (SE), the conduction in the BMN doped film was dominated by bulk processes (PF). The change of the conduction mechanism from SE to PF as a result of BMN doping is attributed to the presence of uncoupled NbTi• sitting as a positive trap center at the shallow donor level of the BST.

Photocatalytic degradation of methyl orange with W-doped TiO2 synthesized by a hydrothermal method

International Nuclear Information System (INIS)

Tian Hua; Ma Junfeng; Li Kang; Li Jinjun

2008-01-01

Nanosized W-doped TiO 2 photocatalysts were synthesized by a simple hydrothermal method, and characterized by energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and BET surface area analyzer. The photocatalytic activity of undoped TiO 2 and W-doped TiO 2 photocatalysts was evaluated by the photocatalytic oxidation degradation of methyl orange in aqueous solution. The results show that the photocatalytic activity of the W-doped TiO 2 photocatalyst is much higher than that of undoped TiO 2 , and the optimum percentage of W doped is 2.0 mol%. The enhanced photocatalytic activity of the doped photocatalyst may be attributed to the increase in the charge separation efficiency and the presence of surface acidity

Photocatalytic Hydrogen or Oxygen Evolution from Water over S- or N-Doped TiO2 under Visible Light

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Kazumoto Nishijima

2008-01-01

Full Text Available S- or N-doping of TiO2 powder having an anatase or rutile phase extended the photocatalytic activity for water oxidation and reduction under UV light and visible light irradiation. For the reduction of water, anatase-doped TiO2 showed higher level of activity than that of doped TiO2 having a rutile phase using ethanol as an electron donor. Furthermore, the activity level of S-doped TiO2 for hydrogen evolution was higher than that of N-doped TiO2 photocatalysts under visible light. Photocatalytic oxidation of water on doped TiO2 having a rutile phase proceeded with fairly high efficiency when Fe3+ ions were used as electron acceptors compared to that on doped TiO2 having an anatase phase. In addition, water splitting under visible light irradiation was achieved by construction of a Z-scheme photocatalysis system employing the doped TiO2 having anatase and rutile phases for H2 and O2 evolution and the I−/IO3− redox couple as an electron relay.

Application of nitrogen-doped TiO2 nano-tubes in dye-sensitized solar cells

DEFF Research Database (Denmark)

Tran, Vy Anh; Thinh Troung, Trieu; Pham Phan, Thu Anh

2017-01-01

Our research aimed to improve the overall energy conversion efficiency of DSCs by applying nitrogen-doped TiO2 nano-tubes (N-TNT) for the preparation of DSCs photo-anodes. The none-doped TiO2 nano-tubes (TNTs) were synthesized by alkaline hydrothermal treatment of Degussa P25 TiO2 particles in 10...

Enhanced Photocatalytic Properties of Ag-Loaded N-Doped Tio2 Nanotube Arrays

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Gao Dawei

2018-03-01

Full Text Available Highly ordered TiO2 nanotube (TiO2 NT arrays were prepared by anodic oxidizing method on the surface of the Ti substrate. Nitrogen-doped TiO2 nanotube (N-TiO2 NT arrays were carried out by ammonia solution immersion, and Ag nanoparticles loaded N-doped TiO2 nanotube (Ag/N-TiO2 NT arrays were obtained by successive ionic layer adsorption and reaction (SILAR technique. The samples were characterized by the X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, field emission scanning electron microscopy (FESEM, high-resolution transmission electron microscopy (HRTEM, photoluminescence (PL emission spectra, ultraviolet–visible (UV–vis diffuse reflectance spectroscopy (DRS. The result indicated that the diameter and wall thickness of the TiO2 NT are 100–120 and 20–30 nm, respectively. Moreover, the morphology and structure of the highly ordered TiO2 NTs were not affected by N-doping. Furthermore, Ag nanoparticles were evenly deposited on the surface of TiO2 NTs in the form of elemental silver. Finally, the photocatalytic activity of Ag/N-TiO2 NTs was evaluated by degradation of methyl orange (MO under visible-light irradiation. The Ag/N-TiO2 NTs exhibited enhanced photocatalytic properties, which could reach 95% after 90-min irradiation.

Effect of concurrent Mg/Nb-doping on dielectric properties of Ba0.45Sr0.55TiO3 thin films

Science.gov (United States)

Alema, Fikadu; Reich, Michael; Reinholz, Aaron; Pokhodnya, Konstantin

2013-08-01

Composition, microstructure, and dielectric properties of undoped and Ba(Mg1/3Nb2/3)O3 (BMN) doped Ba0.45Sr0.55TiO3 (BST) thin films deposited via rf. magnetron sputtering on platinized alumina substrates have been investigated. The analysis of microstructure has shown that despite the sizable effect of doping on the residual stress, the latter is partially compensated by the thermal expansion coefficient mismatch, and its influence on the BST film crystal structure is insignificant. It was revealed that BMN doped film demonstrated an average (over 2000 devices) of 52.5% tunability at 640 kV/cm, which is ˜8% lower than the value for the undoped film. This drop is associated with the presence of Mg ions in BMN; however, the effect of Mg doping is partially compensated by that of Nb ions. The decrease in grain size upon doping may also contribute to the tunability drop. Doping with BMN allows achievement of a compensation concentration yielding no free carriers and resulting in significant leakage current reduction when compared with the undoped film. In addition, the presence of large amounts of empty shallow traps related to NbTi• allows localizing free carriers injected from the contacts thus extending the device control voltage substantially above 10 V.

Microwave-assisted self-doping of TiO2 photonic crystals for efficient photoelectrochemical water splitting

KAUST Repository

Zhang, Zhonghai

2014-01-08

In this article, we report that the combination of microwave heating and ethylene glycol, a mild reducing agent, can induce Ti3+ self-doping in TiO2. A hierarchical TiO2 nanotube array with the top layer serving as TiO2 photonic crystals (TiO2 NTPCs) was selected as the base photoelectrode. The self-doped TiO2 NTPCs demonstrated a 10-fold increase in visible-light photocurrent density compared to the nondoped one, and the optimized saturation photocurrent density under simulated AM 1.5G illumination was identified to be 2.5 mA cm-2 at 1.23 V versus reversible hydrogen electrode, which is comparable to the highest values ever reported for TiO2-based photoelectrodes. The significant enhancement of photoelectrochemical performance can be ascribed to the rational coupling of morphological and electronic features of the self-doped TiO 2 NTPCs: (1) the periodically morphological structure of the photonic crystal layer traps broadband visible light, (2) the electronic interband state induced from self-doping of Ti3+ can be excited in the visible-light region, and (3) the captured light by the photonic crystal layer is absorbed by the self-doped interbands. © 2013 American Chemical Society.

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

International Nuclear Information System (INIS)

Ali, Riyaz Ahmad Mohamed; Nayan, Nafarizal

2011-01-01

The conductivity of Titanium Dioxide (TiO 2 ) 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. TiO 2 was deposited using Ti target in Ar+O 2 (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 -6 Ω.m, Si substrate range is between 3.52x10 -6 to 1.76x10 -5 Ω.m and M substrate range is between 99 to 332 Ω.m. The value of resistivity increases with the thickness of the thin film.

Preparation and photoelectrocatalytic performance of N-doped TiO2/NaY zeolite membrane composite electrode material.

Science.gov (United States)

Cheng, Zhi-Lin; Han, Shuai

2016-01-01

A novel composite electrode material based on a N-doped TiO2-loaded NaY zeolite membrane (N-doped TiO2/NaY zeolite membrane) for photoelectrocatalysis was presented. X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible (UV-vis) and X-ray photoelectron spectroscopy (XPS) characterization techniques were used to analyze the structure of the N-doped TiO2/NaY zeolite membrane. The XRD and SEM results verified that the N-doped TiO2 nanoparticles with the size of ca. 20 nm have been successfully loaded on the porous stainless steel-supported NaY zeolite membrane. The UV-vis result showed that the N-doped TiO2/NaY zeolite membrane exhibited a more obvious red-shift than that of N-TiO2 nanoparticles. The XPS characterization revealed that the doping of N element into TiO2 was successfully achieved. The photoelectrocatalysis performance of the N-doped TiO2/NaY zeolite membrane composite electrode material was evaluated by phenol removal and also the effects of reaction conditions on the catalytic performance were investigated. Owing to exhibiting an excellent catalytic activity and good recycling stability, the N-doped TiO2/NaY zeolite membrane composite electrode material was of promising application for photoelectrocatalysis in wastewater treatment.

Effect of the RE (RE = Eu, Er) doping on the structural and textural properties of mesoporous TiO2 thin films obtained by evaporation induced self-assembly method

International Nuclear Information System (INIS)

Borlaf, Mario; Caes, Sebastien; Dewalque, Jennifer; Colomer, María Teresa; Moreno, Rodrigo; Cloots, Rudi; Boschini, Frederic

2014-01-01

Polymeric sol–gel route has been used for the preparation of TiO 2 and RE 2 O 3– TiO 2 (RE = Eu, Er) mesoporous thin films by evaporation induced self-assembly method using Si (100) as a substrate. The influence of the relative humidity (RH) on the preparation of the film has been studied being necessary to work under 40% RH in order to obtain homogeneous and transparent thin films. The films were annealed at different temperatures until 900 °C/1 h and the anatase crystallization and its crystal size evolution were followed by low angle X-ray diffraction. Neither the anatase–rutile transition nor the formation of other compounds was observed in the studied temperature range. Ellipsoporosimetry studies demonstrated that the thickness of the thin films did not change after calcination at 500 °C, the porosity was constant until 700 °C, the pore size increased and the specific surface area decreased with temperature. Moreover, the effect of the doping with Er 3+ and Eu 3+ was studied and a clear inhibition of the crystal growth and the sintering process was detected (by transmission electron and atomic force microscopy) when the doped films are compared with the undoped ones. Finally, Eu 3+ and Er 3+ f–f transitions were detected by PL measurements. - Highlights: • Eu and Er–TiO 2 mesoporous films were prepared by evaporation induced self-assembly. • Influence of humidity on porosity and photoluminescent properties has been tested. • Influence of calcination on structural and textural properties has been also studied. • f–f transitions indicate that the thin films are active photoluminescent materials

Visible-light photocatalytic activity of nitrided TiO2 thin films

International Nuclear Information System (INIS)

Camps, Enrique; Escobar-Alarcon, L.; Camacho-Lopez, Marco Antonio; Casados, Dora A. Solis

2010-01-01

TiO 2 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 TiO 2 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 TiO 2 and nitrided TiO 2 films. The irradiation of films was carried out with a lamp with emission in the visible (without UV). The results showed that the nitrided TiO 2 films had photocatalytic activity, while the unnitrided films did not.

Structural, optical, and magnetic properties of polycrystalline Co-doped TiO2 synthesized by solid-state method

International Nuclear Information System (INIS)

Bouaine, Abdelhamid; Schmerber, G.; Ihiawakrim, D.; Derory, A.

2012-01-01

Highlights: ► Influence of Co doping on the TiO 2 tetragonal structure. ► Decrease of the energy band gap after doping with Co atoms. ► Appearance of ferromagnetism in Co-doped TiO 2 diluted magnetic semiconductors. - Abstract: We have used a solid-state method to synthesize polycrystalline Co-doped TiO 2 diluted magnetic semiconductors (DMSs) with Co concentrations of 0, and 0.5 at.%. X-ray diffraction patterns reveal that Co doped TiO 2 crystallizes in the rutile tetragonal structure with no additional peaks. Transmission electron microscopy (TEM) did not indicate the presence of magnetic parasitic phases and confirmed that Co ions are uniformly distributed inside the samples. Optical absorbance measurements showed an energy band gap which decreases after doping with the Co atoms into the TiO 2 matrix. Magnetization measurements revealed a paramagnetic behavior for the as-prepared Co-doped TiO 2 and a ferromagnetic behavior for the same samples after annealed under a mixture of H 2 /N 2 atmosphere.

Preparation and spectroscopic characterization of visible light sensitized N doped TiO2 (rutile)

International Nuclear Information System (INIS)

Livraghi, S.; Czoska, A.M.; Paganini, M.C.; Giamello, E.

2009-01-01

Nitrogen doped TiO 2 represents one of the most promising material for photocatalitic degradation of environmental pollutants with visible light. However, at present, a great deal of activity is devoted to the anatase polymorph while few data about rutile are available. In the present paper we report an experimental characterization of N doped polycrystalline rutile TiO 2 prepared via sol-gel synthesis. Nitrogen doping does not affect the valence band to conduction band separation but, generates intra band gap localized states which are responsible of the on set of visible light absorption. The intra band gap states correspond to a nitrogen containing defect similar but not coincident with that recently reported for N doped anatase. - Graphical abstract: Nitrogen doped TiO 2 represents one of the most promising material for photocatalitic degradation of environmental pollutants with visible light. However, at present, a great deal of activity is devoted to the anatase polymorph while few data about rutile are available. In the present paper we report an experimental characterization of N doped polycrystalline rutile TiO 2 prepared via sol-gel synthesis

Synthesis, Structural and Optical Properties of Co Doped TiO2 Nanocrystals by Sol-Gel Method

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D.V. Sridevi

2017-06-01

Full Text Available A TiO2 nanoparticle doped with cobalt was synthesized by sol-gel technique employed at room temperature with appropriate reactants. In the present case, we used titanium tetra isoprotoxide (TTIP and 2–propanol as a common starting material and the obtained products were calcined at 450˚ C. From the Powder XRD data the particle size was calculated by Scherrer method. The FE-SEM analysis shows the morphology of cobalt doped TiO2 nanoparticles. The various functional groups of the samples were identified by Fourier transform spectroscopy (FT-IR. The UV-Vis-NIR spectra of cobalt doped TiO2 material shows two absorption peaks in the visible region related to d-d transitions of Co2+ in TiO2 lattice. Compared to un-doped TiO2 nanoparticles, the cobalt doped material show a red shift in the band gap.

Enhancing the photocatalytic activity of nanocrystalline TiO2 by co-doping with fluorine and yttrium

International Nuclear Information System (INIS)

Zhang, Huarong; Miao, Guashuai; Ma, Xingping; Wang, Bei; Zheng, Haiwu

2014-01-01

Highlights: • (F, Y)-codoped TiO 2 nanoparticles were prepared by a simple sol–gel method. • The highest photocatalytic activity (15 times of that over the pure TiO 2 ) was exhibited in the codoped TiO 2 with 0.05% Y doping level. • The Y doping induced oxygen vancancies played a duel role on the photocatalyic activity of the codoped TiO 2 . • The photocatalytic reactive oxygen species are critical to the photocatalytic degradation processes. - Abstract: Fluorine and yttrium codoped TiO 2 nanoparticles were prepared using a simple sol–gel method. The products were characterized with various spectroscopic and analytical techniques to determine their structural, morphological, optical absorption and photocatalytic properties. The results reveal that neither F nor Y doping causes obvious absorption edge shift in TiO 2 . Photoluminescence (PL) emission spectra present that the PL signal is enhanced, suggesting a decrease of photo-generated charge carrier separation efficiency, after the F or Y doping. The synergistic action by the F and Y doping leads to the highest photocatalytic activity for the degradation of methylene blue solution in the 0.05% (F, Y)-codoped sample (15 times of that over the pure TiO 2 ). With the increase of Y doping level, the photocatalytic performance in the codoped samples increases firstly and then decreases. The photocatalytic activity variations after the F and Y doping were interpreted by the formation of photocatalytic reactive oxygen species induced by the dopings

Annealing temperature effect on the properties of mercury-doped TiO2 films prepared by sol-gel dip-coating technique

International Nuclear Information System (INIS)

Mechiakh, R.; Ben Sedrine, N.; Karyaoui, M.; Chtourou, R.

2011-01-01

This work presents the annealing temperature effect on the properties of mercury (Hg)-doped titanium dioxide (TiO 2 ). Thin films and polycrystalline powders have been prepared by sol-gel process. The structure, surface morphology and optical properties, as a function of the annealing temperature, have been studied by atomic force microscopy (AFM), Raman, reflectance and ellipsometric spectroscopies. In order to determine the transformation points, we have analyzed the xerogel-obtained powder by differential scanning calorimetry (DSC). Raman spectroscopy shows the crystalline anatase and rutile phases for the films annealed at 400 deg. C and 1000 deg. C respectively. The AFM surface morphology results indicate that the particle size increases from 14 to 57 nm by increasing the annealing temperature. The complex index and the optical band gap (E g ) of the films were determined by the spectroscopic ellipsometry analysis. We have found that the optical band gap decreases by increasing the annealing temperature.

Carbon nanotube TiO2 hybrid films for detecting traces of O2

Science.gov (United States)

Llobet, E.; Espinosa, E. H.; Sotter, E.; Ionescu, R.; Vilanova, X.; Torres, J.; Felten, A.; Pireaux, J. J.; Ke, X.; Van Tendeloo, G.; Renaux, F.; Paint, Y.; Hecq, M.; Bittencourt, C.

2008-09-01

Hybrid titania films have been prepared using an adapted sol-gel method for obtaining well-dispersed hydrogen plasma-treated multiwall carbon nanotubes in either pure titania or Nb-doped titania. The drop-coating method has been used to fabricate resistive oxygen sensors based on titania or on titania and carbon nanotube hybrids. Morphology and composition studies have revealed that the dispersion of low amounts of carbon nanotubes within the titania matrix does not significantly alter its crystallization behaviour. The gas sensitivity studies performed on the different samples have shown that the hybrid layers based on titania and carbon nanotubes possess an unprecedented responsiveness towards oxygen (i.e. more than four times higher than that shown by optimized Nb-doped TiO2 films). Furthermore, hybrid sensors containing carbon nanotubes respond at significantly lower operating temperatures than their non-hybrid counterparts. These new hybrid sensors show a strong potential for monitoring traces of oxygen (i.e. beverage industry.

Electrical Transport Ability of Nanostructured Potassium-Doped Titanium Oxide Film

Science.gov (United States)

Lee, So-Yoon; Matsuno, Ryosuke; Ishihara, Kazuhiko; Takai, Madoka

2011-02-01

Potassium-doped nanostructured titanium oxide films were fabricated using a wet corrosion process with various KOH solutions. The doped condition of potassium in TiO2 was confirmed by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Nanotubular were synthesized at a dopant concentration of 0.27%, these structures disappeared. To investigate the electrical properties of K-doped TiO2, pseudo metal-oxide-semiconductor field-effect transistor (MOSFET) samples were fabricated. The samples exhibited a distinct electrical behavior and p-type characteristics. The electrical behavior was governed by the volume of the dopant when the dopant concentration was 0.18%.

Superhydrophilicity of TiO2 nano thin films

International Nuclear Information System (INIS)

Mohammadizadeh, M.R.; Ashkarran, A.A.

2007-01-01

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 TiO 2 thin films has been accepted although, the origin of hydrophilicity property has not been recognized completely yet. TiO 2 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/cm 2 UV irradiation. TiO 2 thin film on Si(111), Si(100), and quartz substrates needs less time to be converted to

Preparation and Photocatalytic Activity of Nitrogen-doped Nano TiO2/Tourmaline Composites

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LIU Xin-wei

2016-06-01

Full Text Available Using Ti(OC4H94 as precursor, CO(NH22 as nitrogen source, tourmaline as support, the nitrogen-doped nano TiO2/tourmaline composites were synthesized by sol-gel method with ultrasound assisted.The structure and performance of composites were characterized by XRD, FT-IR, UV-Vis DRS, SEM, EDS.The effects of calcining temperature, nitrogen-doped content, tourmaline amount, catalyst system on the photocatalytic activity of nitrogen-doped nano TiO2/tourmaline composites were studied.The results show that the photocatalytic activity of nitrogen-doped nano TiO2/tourmaline composites calcined under 500℃, the nitrogen doped amount of 5% (mole fraction, tourmaline added in an amount of 10% (mass fraction, catalyst dosage of 3g/L, under 500W UV light irradiation conditions, the photocatalytic degradation effect of TNT(10mg/L is the best, and has a good recycling performance.

N-doped TiO2 photo-catalyst for the degradation of 1,2-dichloroethane under fluorescent light

International Nuclear Information System (INIS)

Lin, Yi-Hsing; Chiu, Tang-Chun; Hsueh, Hsin-Ta; Chu, Hsin

2011-01-01

The photo-catalytic degradation of 1,2-dichloroethane (1, 2-DCE) using nitrogen-doped TiO 2 photo-catalysts under fluorescent light irradiation was investigated. Highly pure TiO 2 and nitrogen-doped TiO 2 were prepared by a sol-gel method and characterized by thermo-gravimetric/differential-thermal analysis (TG/DTA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy. The results indicate that the photo-catalysts were mainly nano-size with an anatase-phase structure. The degradation reaction of 1,2-DCE was operated under visible-light irradiation, and the photo-catalytic oxidation was conducted in a batch photo-reactor with various nitrogen doping ratios (N/Ti = 0-25 mol%). The relative humidity (RH) was controlled at 0-20% and the oxygen concentration was controlled at 0-21%. The photo-degradation with nitrogen-doped TiO 2 showed superior photo-catalytic activity compared to that for pure TiO 2 . TiO 2 doped with 15 mol% nitrogen exhibited the best photo-catalytic efficiency under the tested conditions. The products from the 1,2-DCE photo-catalytic oxidation were CO 2 and water; the by-products included dichloromethane, methyl chloride, ethyl chloride, carbon monoxide, and hydrogen chloride. The reaction pathway of 1,2-DCE indicates that oxygen molecules are the major factor that causes the degradation of 1,2-DCE in the gas phase.

Low-temperature sputtering of crystalline TiO2 films

International Nuclear Information System (INIS)

Musil, J.; Herman, D.; Sicha, J.

2006-01-01

This article reports on the investigation of reactive magnetron sputtering of transparent, crystalline titanium dioxide films. The aim of this investigation is to determine a minimum substrate surface temperature T surf necessary to form crystalline TiO 2 films with anatase structure. Films were prepared by dc pulsed reactive magnetron sputtering using a dual magnetron operating in bipolar mode and equipped with Ti(99.5) and ceramic Ti 5 O 9 targets. The films were deposited on unheated glass substrates and their structure was characterized by x-ray diffraction and surface morphology by atomic force microscopy. Special attention is devoted to the measurement of T surf using thermostrips pasted to the glass substrate. It was found that (1) T surf is considerably higher (approximately by 100 deg. C or more) than the substrate temperature T s measured by the thermocouple incorporated into the substrate holder and (2) T surf strongly depends on the substrate-to-target distance d s-t , the magnetron target power loading, and the thermal conductivity of the target and its cooling. The main result of this study is the finding that (1) the crystallization of sputtered TiO 2 films depends not only on T surf but also on the total pressure p T of sputtering gas (Ar+O 2 ), partial pressure of oxygen p O 2 , the film deposition rate a D , and the film thickness h (2) crystalline TiO 2 films with well developed anatase structure can be formed at T surf =160 deg. C and low values of a D ≅5 nm/min (3) the crystalline structure of TiO 2 film gradually changes from (i) anatase through (ii) anatase+rutile mixture, and (iii) pure rutile to x-ray amorphous structure at T surf =160 deg. C and p T =0.75 Pa when p O 2 decreases and a D increases above 5 nm/min, and (4) crystallinity of the TiO 2 films decreases with decreasing h and T surf . Interrelationships between the structure of TiO 2 film, its roughness, T surf , and a D are discussed in detail. Trends of next development are

Dielectric response and room temperature ferromagnetism in Cr doped anatase TiO2 nanoparticles

Science.gov (United States)

Naseem, Swaleha; Khan, Wasi; Khan, Shakeel; Husain, Shahid; Ahmad, Abid

2018-02-01

In the present work, nanocrystalline samples of Ti1-xCrxO2 (x = 0, 0.02, 0.04, 0.06 and 0.08) were synthesized in anatase phase through simple and cost effective acid modified sol gel method. The influence of Cr doping on thermal, microstructural, electrical and magnetic properties was investigated in TiO2 host matrix. The surface morphology has revealed less agglomeration and considerable reduction in particle size in case of Cr doped TiO2 as compared to undoped TiO2 nanoparticles (NPs). Energy dispersive x-ray spectroscopy (EDS), Raman and X-ray photoelectron spectroscopy (XPS) established high purity, appropriate stoichiometry and oxidation states of the compositions. The dielectric properties of the nanoparticles were altered by the doping concentration, applied frequency as well as temperature variation. The variation in dielectric constant (ε‧), dielectric loss (δ) and ac conductivity as a function of frequency and temperature at different doping concentration of Cr were interpreted in the light of Maxwell Wagner theory, space charge polarization mechanism and drift mobility of charge carriers. Both undoped and Cr doped TiO2 samples exhibit room temperature ferromagnetism (RTFM) that remarkably influenced by means of the Cr content. The significant enhancement in the magnetization was observed at 4% Cr doping. However, decrease in magnetization for higher doping signify antiferromagnetic interactions between Cr ions or superexchange mechanism. These results reveal that the oxygen vacancies play a crucial role to initiate the RTFM. Therefore, the present investigation suggests the potential applications of Cr doped TiO2 nanoparticles for spintronics application.

Characterization and improved solar light activity of vanadium doped TiO2/diatomite hybrid catalysts

International Nuclear Information System (INIS)

Wang, Bin; Zhang, Guangxin; Leng, Xue; Sun, Zhiming; Zheng, Shuilin

2015-01-01

Highlights: • V-doped TiO 2 /diatomite composite photocatalyst was synthesized. • The physiochemical property and solar light photoactivity were characterized. • The presence and influence of V ions in TiO 2 matrix was systematically analyzed. • The photocatalysis for Rhodamine B were studied under solar light illumination. - Abstract: V-doped TiO 2 /diatomite composite photocatalysts with different vanadium concentrations were synthesized by a modified sol–gel method. The diatomite was responsible for the well dispersion of TiO 2 nanoparticles on the matrix and consequently inhibited the agglomeration. V-TiO 2 /diatomite hybrids showed red shift in TiO 2 absorption edge with enhanced absorption intensity. Most importantly, the dopant energy levels were formed in the TiO 2 bandgap due to V 4+ ions substituted to Ti 4+ sites. The 0.5% V-TiO 2 /diatomite photocatalyst displayed narrower bandgap (2.95 eV) compared to undoped sample (3.13 eV) and other doped samples (3.05 eV) with higher doping concentration. The photocatalytic activities of V doped TiO 2 /diatomite samples for the degradation of Rhodamine B under stimulated solar light illumination were significantly improved compared with the undoped sample. In our case, V 4+ ions incorporated in TiO 2 lattice were responsible for increased visible-light absorption and electron transfer to oxygen molecules adsorbed on the surface of TiO 2 to produce superoxide radicals ·O 2 – , while V 5+ species presented on the surface of TiO 2 particles in the form of V 2 O 5 contributed to e – –h + separation. In addition, due to the combination of diatomite as support, this hybrid photocatalyst could be separated from solution quickly by natural settlement and exhibited good reusability

Photocatalysis with chromium-doped TiO2: Bulk and surface doping

KAUST Repository

Ould-Chikh, Samy; Proux, Olivier; Afanasiev, Pavel V.; Khrouz, Lhoussain; Hedhili, Mohamed N.; Anjum, Dalaver H.; Harb, Moussab; Geantet, Christophe; Basset, Jean-Marie; Puzenat, Eric

2014-01-01

The photocatalytic properties of TiO2 modified by chromium are usually found to depend strongly on the preparation method. To clarify this problem, two series of chromium-doped titania with a chromium content of up to 1.56 wt % have been prepared

Effect of V-Nd co-doping on phase transformation and grain growth process of TiO2

Science.gov (United States)

Khatun, Nasima; Amin, Ruhul; Anita, Sen, Somaditya

2018-05-01

The pure and V-Nd co-doped TiO2 samples are prepared by the modified sol-gel process. The phase formation is confirmed by XRD spectrum. Phase transformation is delayed in V-Nd co-doped TiO2 (TVN) samples compared to pure TiO2. The particle size is comparatively small in TVN samples at both the temperature 450 °C and 900 °C. Hence the effect of Nd doping is dominated over V doping in both phase transformation and grain growth process of TiO2.

Phosphorus doped TiO2 as oxygen sensor with low operating temperature and sensing mechanism

International Nuclear Information System (INIS)

Han, Zhizhong; Wang, Jiejie; Liao, Lan; Pan, Haibo; Shen, Shuifa; Chen, Jianzhong

2013-01-01

Nano-scale TiO 2 powders doped with phosphorus were prepared by sol–gel method. The characterization of the materials was performed by XRD, BET, FT-IR spectroscopy, Zeta potential measurement and XPS analysis. The results indicate that the phosphorus suppresses the crystal growth and phase transformation and, at the same time, increases the surface area and enhances the sensitivity and selectivity for the P-doped TiO 2 oxygen sensors. In this system, the operating temperature is low, only 116 °C, and the response time is short. The spectra of FT-IR and XPS show that the phosphorus dopant presents as the pentavalent-oxidation state in TiO 2 , further phosphorus can connect with Ti 4+ through the bond of Ti-O-P. The positive shifts of XPS peaks indicate that electron depleted layer of P-doped TiO 2 is narrowed compared with that of pure TiO 2 , and the results of Zeta potential illuminate that the density of surface charge carrier is intensified. The adsorptive active site and Lewis acid characteristics of the surface are reinforced by phosphorus doping, where phosphorus ions act as a new active site. Thus, the sensitivity of P-doped TiO 2 is improved, and the 5 mol% P-doped sample has the optimal oxygen sensing properties.

Preparation of Fluorine-Doped TiO2 Photocatalysts with Controlled Crystalline Structure

Directory of Open Access Journals (Sweden)

N. Todorova

2008-01-01

Full Text Available Nanocrystalline F-doped TiO2 powders were prepared by sol-gel route. The thermal behavior of the powders was recorded by DTA/TG technique. The crystalline phase of the fluorinated TiO2 powders was determined by X-ray diffraction technique. It was demonstrated that F-doping using CF3COOH favors the formation of rutile along with anatase phase even at low temperature. Moreover, the rutile's phase content increases with the increase of the quantity of the fluorine precursor in the starting solution. The surface area of the powders and the pore size distribution were studied by N2 adsorption-desorption using BET and BJH methods. X-ray photoelectron spectroscopy (XPS revealed that the fluorine is presented in the TiO2 powders mainly as metal fluoride in quantities ∼16 at %. The F-doped TiO2 showed a red-shift absorption in UV-vis region which was attributed to the increased content of rutile phase in the powders. The powders exhibited enhanced photocatalytic activity in decomposition of acetone.

A comparative study of two techniques for determining photocatalytic activity of nitrogen doped TiO2 nanotubes under visible light irradiation: Photocatalytic reduction of dye and photocatalytic oxidation of organic molecules

DEFF Research Database (Denmark)

In, Su-Il; Vesborg, Peter Christian Kjærgaard; Abrams, Billie

2011-01-01

Nitrogen-doping (N-doping) is a popular strategy for promoting the absorption of visible light in TiO2 and other photocatalysts. We have grown TiO2 nanotubes onto non-conducting Pyrex in a one step process via single layer titanium films. In an attempt to improve the self-cleaning ability of vert...

TiO2 and SiC nanostructured films, organized CNT structures

Indian Academy of Sciences (India)

sized nanostructured TiO2 films through hydrolysis of titanium tetra-isopropoxide. (TTIP) [9 ... structured TiO2 as a photocatalyst is as follows [15]:. TiO2(ns) ... The deposited films were easily detached from the silica tube and subjected to. SEM.

Visible Light Photoelectrochemical Properties of N-Doped TiO2 Nanorod Arrays from TiN

Directory of Open Access Journals (Sweden)

Zheng Xie

2013-01-01

Full Text Available N-doped TiO2 nanorod arrays (NRAs were prepared by annealing the TiN nanorod arrays (NRAs which were deposited by using oblique angle deposition (OAD technique. The TiN NRAs were annealed at 330°C for different times (5, 15, 30, 60, and 120 min. The band gaps of annealed TiN NRAs (i.e., N-doped TiO2 NRAs show a significant variance with annealing time, and can be controlled readily by varying annealing time. All of the N-doped TiO2 NRAs exhibit an enhancement in photocurrent intensity in visible light compared with that of pure TiO2 and TiN, and the one annealed for 15 min shows the maximum photocurrent intensity owning to the optimal N dopant concentration. The results show that the N-doped TiO2 NRAs, of which the band gap can be tuned easily, are a very promising material for application in photocatalysis.

Facile synthesis and characterization of N-doped TiO2/C nanocomposites with enhanced visible-light photocatalytic performance

Science.gov (United States)

Jia, Tiekun; Fu, Fang; Yu, Dongsheng; Cao, Jianliang; Sun, Guang

2018-02-01

Ultrafine anatase N-doped TiO2 nanocrystals modified with carbon (denoted as N-doped TiO2/C) were successfully prepared via a facile and low-cost approach, using titanium tetrachloride, aqueous ammonia and urea as starting materials. The phase composition, surface chemical composition, morphological structure, electronic and optical properties of the as-prepared photocatalysts were well characterized and analyzed. On the basis of Raman spectral characterization combining with the results of X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM), it could be concluded that N dopant ions were successfully introduced into TiO2 crystal lattice and carbon species were modified on the surface or between the nanoparticles to form N-doped TiO2/C nanocomposites. Compared with that of bare TiO2, the adsorption band edge of N-doped TiO2/C nanocomposites were found to have an evident red-shift toward visible light region, implying that the bandgap of N-doped TiO2/C nanocomposites is narrowed and the visible light absorption capacity is significantly enhanced due to N doping and carbon modification. The photoactivity of the as-prepared photocatalytsts was tested by the degradation of Rhodamine B (RhB) under visible light (λ > 420 nm), and the results showed that the N-doped TiO2/C nanocomposites exhibited much higher photodegradation rate than pure TiO2 and N-doped TiO2, which was mainly attributed to the synergistic effect of the enhanced light harvesting, augmented catalytic active sites and efficient separation of photogenerated electron-hole pairs.

The Effects of Doping Copper and Mesoporous Structure on Photocatalytic Properties of TiO2

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Yang Wang

2014-01-01

Full Text Available This paper describes a system for the synthesis of Cu-doped mesoporous TiO2 nanoparticles by a hydrothermal method at relatively low temperatures. The technique used is to dope the as-prepared mesoporous TiO2 system with copper. In this method, the copper species with the form of Cu1+, which was attributed to the reduction effect of dehydroxylation and evidenced by X-ray photoelectron spectroscopy (XPS and X-ray diffraction (XRD, was well dispersed in the optimal concentration 1 wt.% Cu-doped mesoporous TiO2. In this as-prepared mesoporous TiO2 system, original particles with a size of approximately 20 nm are aggregated together to shapes of approximately 1100 nm, which resulted in the porous aggregate structure. More importantly, the enhancement of the photocatalytic activity was discussed as effects due to the formation of stable Cu(I and the mesoporous structure in the Cu-doped mesoporous TiO2. Among them, Cu-doped mesoporous TiO2 shows the highest degradation rate of methyl orange (MO. In addition, the effects of initial solution pH on degradation of MO had also been investigated. As a result, the optimum values of initial solution pH were found to be 3.

Photoelectrochemical oxidation of ibuprofen via Cu_2O-doped TiO_2 nanotube arrays

International Nuclear Information System (INIS)

Sun, Qiannan; Peng, Yen-Ping; Chen, Hanlin; Chang, Ken-Lin; Qiu, Yang-Neng; Lai, Shiau-Wu

2016-01-01

Highlights: • A p–n junction material was synthesized to enhance photocatalytic ability. • Cu_2O-doped TiO_2 nanotube arrays works as a photoanode in a PEC system. • Recombination of photo-generated holes and electrons were greatly reduced. • Synergetic effect was quantified in PEC degradation. • Recombination of photogenerated holes and electrons was greatly enhanced. - Abstract: A p–n junction based Cu_2O-doped TiO_2 nanotube arrays (Cu_2O-TNAs) were synthesized and used as a working anode in a photoelectrochemical (PEC) system. The results revealed that the Cu_2O-TNAs were dominated by the anatase phase and responded significantly to visible light. XPS analyses indicated that with an amount of 24.79% Cu doping into the structure, the band gap of Cu_2O-TNAs was greatly reduced. SEM images revealed that the supported TiO_2 nanotubes had diameters of approximately 80 nm and lengths of about 2.63 μm. Upon doping with Cu_2O, the TiO_2 nanotubes maintained their structural integrity, exhibiting no significant morphological change, favoring PEC applications. Under illumination, the photocurrent from Cu_2O/TNAs was 2.4 times larger than that from TNAs, implying that doping with Cu_2O significantly improved electron mobility by reducing the rate of recombination of electron-hole pairs. The EIS and Bode plot revealed that the estimated electron lifetimes, τ_e_l, of TNAs and Cu_2O/TNAs were 6.91 and 26.26 ms, respectively. The efficiencies of degradation of Ibuprofen by photoelectrochemical, photocatalytic (PC), electrochemical (EC) and photolytic (P) methods were measured.

Photocatalytic degradation of methylene blue on Fe3+-doped TiO2 nanoparticles under visible light irradiation

Institute of Scientific and Technical Information of China (English)

SU Bitao; WANG Ke; BAI Jie; MU Hongmei; TONG Yongchun; MIN Shixiong; SHE Shixiong; LEI Ziqiang

2007-01-01

Fe3+-doped TiO2 composite nanoparticles with different doping amounts were successfully synthesized using sol-gel method and characterized by X-ray diffraction (XRD),transmission electron microscopy (TEM) and ultraviolet-visible spectroscopy (UV-Vis) diffuse reflectance spectra (DRS). The photocatalytic degradation of methylene blue was used as a model reaction to evaluate the photocatalytic activity of Fe3+/TiO2 nanoparticles under visible light irradia-tion. The influence of doping amount of Fe3+ (ω: 0.00%-3.00%) on photocatalytic activities of TiO2 was investigated.Results show that the size of Fe3+/TiO2 particles decreases with the increase of the amount of Fe3+ and their absorptionspectra are broaden and absorption intensities are also increased. Doping Fe3+ can control the conversion of TiO2 from anatase to rutile. The doping amount of Fe3+ remarkably affects the activity of the catalyst, and the optimum efficiency occurs at about the doping amount of 0.3%. The appropriate doping of Fe3+ can markedly increase the catalytic activity of TiO2 under visible light irradiation.

Influence of surfactant and annealing temperature on optical properties of sol-gel derived nano-crystalline TiO2 thin films.

Science.gov (United States)

Vishwas, M; Sharma, Sudhir Kumar; Rao, K Narasimha; Mohan, S; Gowda, K V Arjuna; Chakradhar, R P S

2010-03-01

Titanium dioxide thin films have been synthesized by sol-gel spin coating technique on glass and silicon substrates with and without surfactant polyethylene glycol (PEG). XRD and SEM results confirm the presence of nano-crystalline (anatase) phase at an annealing temperature of 300 degrees C. The influence of surfactant and annealing temperature on optical properties of TiO(2) thin films has been studied. Optical constants and film thickness were estimated by Swanepoel's (envelope) method and by ellipsometric measurements in the visible spectral range. The optical transmittance and reflectance were found to decrease with an increase in PEG percentage. Refractive index of the films decreased and film thickness increased with the increase in percentage of surfactant. The refractive index of the un-doped TiO(2) films was estimated at different annealing temperatures and it has increased with the increasing annealing temperature. The optical band gap of pure TiO(2) films was estimated by Tauc's method at different annealing temperature. Copyright 2010 Elsevier B.V. All rights reserved.

Enhanced photovoltaic performance of inverted hybrid bulk-heterojunction solar cells using TiO2/reduced graphene oxide films as electron transport layers

Science.gov (United States)

Morais, Andreia; Alves, João Paulo C.; Lima, Francisco Anderson S.; Lira-Cantu, Monica; Nogueira, Ana Flavia

2015-01-01

In this study, we investigated inverted hybrid bulk-heterojunction solar cells with the following configuration: fluorine-doped tin oxide (FTO) |TiO2/RGO|P3HT:PC61BM|V2O5 or PEDOT:PSS|Ag. The TiO2/GO dispersions were prepared by sol-gel method, employing titanium isopropoxide and graphene oxide (GO) as starting materials. The GO concentration was varied from 0.1 to 4.0 wt%. The corresponding dispersions were spin-coated onto FTO substrates and a thermal treatment was performed to remove organic materials and to reduce GO to reduced graphene oxide (RGO). The TiO2/RGO films were characterized by x-ray diffraction, Raman spectroscopy, and microscopy techniques. Atomic force microscopy (AFM) images showed that the addition of RGO significantly changes the morphology of the TiO2 films, with loss of uniformity and increase in surface roughness. Independent of the use of V2O5 or PEDOT: PSS films as the hole transport layer, the incorporation of 2.0 wt% of RGO into TiO2 films was the optimal concentration for the best organic photovoltaic performance. The solar cells based on TiO2/RGO (2.0 wt%) electrode exhibited a ˜22.3% and ˜28.9% short circuit current density (Jsc) and a power conversion efficiency enhancement, respectively, if compared with the devices based on pure TiO2 films. Kelvin probe force microscopy images suggest that the incorporation of RGO into TiO2 films can promote the appearance of regions with different charge dissipation capacities.

Eco-friendly synthesis of TiO2, Au and Pt doped TiO2 nanoparticles for dye sensitized solar cell applications and evaluation of toxicity

Science.gov (United States)

Gopinath, K.; Kumaraguru, S.; Bhakyaraj, K.; Thirumal, S.; Arumugam, A.

2016-04-01

Driven by the demand of pure TiO2, Au and Pt doped TiO2 NPs were successfully synthesized using Terminalia arjuna bark extract. The eco-friendly synthesized NPs were characterized by UV-Vis-DRS, ATR-FT-IR, PL, XRD, Raman, SEM with EDX and TEM analysis. The synthesized NPs were investigation for dye sensitized solar cell applications. UV-Vis-Diffused Reflectance Spectra clearly showed that the expected TiO2 inter band absorption below 306 nm, incorporation of gold shows surface plasma resonant (SPR) near 555 nm and platinum incorporated TiO2 NPs shows absorbance at 460 nm. The energy conversion efficiency for Au doped TiO2 NPs when compared to pure and Pt doped TiO2 NPs. In addition to that, Au noble metal present TiO2 matrix and an improve open-circuit voltage (Voc) of DSSC. Synthesized NPs was evaluated into antibacterial and antifungal activities by disk diffusion method. It is observed that NPs have not shown any activities in all tested bacterial and fungal strains. In this eco-friendly synthesis method to provide non toxic and environmental friendly nanomaterials can be used for solar energy device application.

Formation of Sol Gel Dried Droplets of Carbon Doped Titanium Dioxide (TiO2) at Low Temperature via Electrospraying

Science.gov (United States)

Halimi, S. U.; Hashib, S. Abd; Abu Bakar, N. F.; Ismail, S. N.; Nazli Naim, M.; Rahman, N. Abd; Krishnan, J.

2018-05-01

The high band gap energy of TiO2 and inconsistency in particles size has imposed a significant drawback on TiO2 applications. Dried droplets of carbon-doped TiO2 fine particles were produced by using electrospraying technique. The C-doped TiO2 particles were prepared by hydrolysis of titanium isopropoxide with the addition of carbon precursor followed by electrospraying the suspension in stable Taylor cone-jet mode. Coulomb fission of charged droplets from the electrospraying technique successfully transformed dispersed liquid C-doped TiO2 particles into solid. The deposited C-doped TiO2 droplets were collected on aluminium substrates placed at working distances of 10 to 20 cm from the tip of the electrospray needle. The collected C-doped TiO2 droplets were characterized by using FESEM, UV-Vis, FTIR and XRD. By increasing the working distance, the average droplets size of the deposited C-doped TiO2 was reduced from ±163.2 nm to ±147.56 nm. UV-Vis analysis showed a strong absorption in the visible-light region and about 93 nm red shift of the onset spectrum for C-doped TiO2. The red shift indicates an increase in photocatalytic efficiency by reducing the TiO2 band gap energy from 3.0 eV to 2.46 eV and shifting its activity to the visible-light region. FTIR analysis indicated the presence of Ti-C and C-O chemical bonding in the C-doped TiO2.

Sulphur doped nanoparticles of TiO2

Czech Academy of Sciences Publication Activity Database

Szatmáry, Lórant; Bakardjieva, Snejana; Šubrt, Jan; Bezdička, Petr; Jirkovský, Jaromír; Bastl, Zdeněk; Brezová, V.; Korenko, M.

2011-01-01

Roč. 161, č. 1 (2011), s. 23-28 ISSN 0920-5861 R&D Projects: GA MŠk 1M0577 Institutional research plan: CEZ:AV0Z40400503; CEZ:AV0Z40320502 Keywords : photocatalyst * S-doped TiO2 * Thiourea Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.407, year: 2011

Influence of Pore Size on the Optical and Electrical Properties of Screen Printed TiO2 Thin Films

Directory of Open Access Journals (Sweden)

Dinfa Luka Domtau

2016-01-01

Full Text Available Influence of pore size on the optical and electrical properties of TiO2 thin films was studied. TiO2 thin films with different weight percentages (wt% of carbon black were deposited by screen printing method on fluorine doped tin oxide (FTO coated on glass substrate. Carbon black decomposed on annealing and artificial pores were created in the films. All the films were 3.2 µm thick as measured by a surface profiler. UV-VIS-NIR spectrophotometer was used to study transmittance and reflectance spectra of the films in the photon wavelength of 300–900 nm while absorbance was studied in the range of 350–900 nm. Band gaps and refractive index of the films were studied using the spectra. Reflectance, absorbance, and refractive index were found to increase with concentrations of carbon black. There was no significant variation in band gaps of films with change in carbon black concentrations. Transmittance reduced as the concentration of carbon black in TiO2 increased (i.e., increase in pore size. Currents and voltages (I-V characteristics of the films were measured by a 4-point probe. Resistivity (ρ and conductivity (σ of the films were computed from the I-V values. It was observed that resistivity increased with carbon black concentrations while conductivity decreased as the pore size of the films increased.

Nb-doped TiO2 thin films as photocatalytic materials

Indian Academy of Sciences (India)

Administrator

that hydrophilicity is ruled by a different mechanism than photocatalysis. Keywords. Nb-doped ... studied for a large area of applications: solar cells,1–3 hydrogen ... our previous work.12,13 Results show that all the films are amorphous and ...

Heterogeneous photocatalytic degradation of toluene in static environment employing thin films of nitrogen-doped nano-titanium dioxide

Science.gov (United States)

Kannangara, Yasun Y.; Wijesena, Ruchira; Rajapakse, R. M. G.; de Silva, K. M. Nalin

2018-04-01

Photocatalytic semiconductor thin films have the ability to degrade volatile organic compounds (VOCs) causing numerous health problems. The group of VOCs called "BTEX" is abundant in houses and indoor of automobiles. Anatase phase of TiO2 has a band gap of 3.2 eV and UV radiation is required for photogeneration of electrons and holes in TiO2 particles. This band gap can be decreased significantly when TiO2 is doped with nitrogen (N-TiO2). Dopants like Pd, Cd, and Ag are hazardous to human health but N-doped TiO2 can be used in indoor pollutant remediation. In this research, N-doped TiO2 nano-powder was prepared and characterized using various analytical techniques. N-TiO2 was made in sol-gel method and triethylamine (N(CH2CH3)3) was used as the N-precursor. Modified quartz cell was used to measure the photocatalytic degradation of toluene. N-doped TiO2 nano-powder was illuminated with visible light (xenon lamp 200 W, λ = 330-800 nm, intensity = 1 Sun) to cause the degradation of VOCs present in static air. Photocatalyst was coated on a thin glass plate, using the doctor-blade method, was inserted into a quartz cell containing 2.00 µL of toluene and 35 min was allowed for evaporation/condensation equilibrium and then illuminated for 2 h. Remarkably, the highest value of efficiency 85% was observed in the 1 μm thick N-TiO2 thin film. The kinetics of photocatalytic degradation of toluene by N-TiO2 and P25-TiO2 has been compared. Surface topology was studied by varying the thickness of the N-TiO2 thin films. The surface nanostructures were analysed and studied with atomic force microscopy with various thin film thicknesses.

Mo-doped Gray Anatase TiO2: Lattice Expansion for Enhanced Sodium Storage

International Nuclear Information System (INIS)

Liao, Hanxiao; Xie, Lingling; Zhang, Yan; Qiu, Xiaoqing; Li, Simin; Huang, Zhaodong; Hou, Hongshuai; Ji, Xiaobo

2016-01-01

Gray-colored Mo 6+ -doped anatase TiO 2 is prepared uniformly with particle size of 10–20 nm, and is firstly employed as anode material in sodium-ion batteries (SIBs), presenting excellent electrochemical performances. It delivered reversible specific capacities of 231.8 mAh g −1 at 0.1 C (33.5 mA g −1 ) after 100 cycles and 108.3 mAh g −1 at 5 C (1.68 A g −1 ), comparing to 170.5 mAh g −1 at 0.1 C and only 41.7 mAh g −1 at 5C for the bare TiO 2 . The improved electrochemical performances might be beneficial from the doping of Mo 6+ , which can effectively enhance the conductivity of TiO 2 resulting from induced conduction band electrons, interstitial oxygen defects and vacancies. In addition, the doping can also lead to the lattice expansion, which can facilitate the diffusion of Na + . In combination with natural abundance and environmental benignity, Mo 6+ -doped TiO 2 can be expected to be utilized as an anode material for enhanced sodium storage.

Vacancy identification in Co+ doped rutile TiO2 crystal with positron annihilation spectroscopy

Science.gov (United States)

Qin, X. B.; Zhang, P.; Liang, L. H.; Zhao, B. Z.; Yu, R. S.; Wang, B. Y.; Wu, W. M.

2011-01-01

Co-doped rutile TiO2 films were synthesized by ion implantation. Variable energy positron annihilation Doppler broadening spectroscopy and coincidence Doppler broadening measurements were performed for identification of the vacancies. A newly formed type of vacancy can be concluded by the S-W plot and the CDB results indicated that the oxygen vacancy (VO) complex Ti-Co-VO and/or Ti-VO are formed with Co ions implantation and the vacancy concentration is increased with increase of dopant dose.

Improved conversion efficiency of dye sensitized solar cell using Zn doped TiO_2-ZrO_2 nanocomposite

International Nuclear Information System (INIS)

Tomar, Laxmi J.; Bhatt, Piyush J.; Desai, Rahul K.; Chakrabarty, B. S.; Panchal, C. J.

2016-01-01

TiO_2-ZrO_2 and Zn doped TiO_2-ZrO_2 nanocomposites were prepared by hydrothermal method for dye sensitized solar cell (DSSC) application. The structural and optical properties were investigated by X –ray diffraction (XRD) and UV-Visible spectroscopy respectively. XRD results revealed the formation of material in nano size. The average crystallite size is 22.32 nm, 17.41 nm and 6.31 nm for TiO_2, TiO_2-ZrO_2 and Zn doped TiO_2-ZrO_2 nanocomposites respectively. The optical bandgap varies from 2.04 eV to 3.75 eV. Dye sensitized solar cells were fabricated using the prepared material. Pomegranate juice was used as a sensitizer and graphite coated conducting glass plate was used as counter electrode. The I – V characteristics were recorded to measure photo response of DSSC. Photovoltaic parameter like open circuit voltage, power conversion efficiency, and fill factor were evaluated for fabricated solar cell. The power conversion efficiency of DSSC fabricated with TiO_2, TiO_2-ZrO_2 and Zn doped TiO_2-ZrO_2 nanocomposites were found 0.71%, 1.97% and 4.58% respectively.

Improved conversion efficiency of dye sensitized solar cell using Zn doped TiO2-ZrO2 nanocomposite

Science.gov (United States)

Tomar, Laxmi J.; Bhatt, Piyush J.; Desai, Rahul K.; Chakrabarty, B. S.; Panchal, C. J.

2016-05-01

TiO2-ZrO2 and Zn doped TiO2-ZrO2 nanocomposites were prepared by hydrothermal method for dye sensitized solar cell (DSSC) application. The structural and optical properties were investigated by X -ray diffraction (XRD) and UV-Visible spectroscopy respectively. XRD results revealed the formation of material in nano size. The average crystallite size is 22.32 nm, 17.41 nm and 6.31 nm for TiO2, TiO2-ZrO2 and Zn doped TiO2-ZrO2 nanocomposites respectively. The optical bandgap varies from 2.04 eV to 3.75 eV. Dye sensitized solar cells were fabricated using the prepared material. Pomegranate juice was used as a sensitizer and graphite coated conducting glass plate was used as counter electrode. The I - V characteristics were recorded to measure photo response of DSSC. Photovoltaic parameter like open circuit voltage, power conversion efficiency, and fill factor were evaluated for fabricated solar cell. The power conversion efficiency of DSSC fabricated with TiO2, TiO2-ZrO2 and Zn doped TiO2-ZrO2 nanocomposites were found 0.71%, 1.97% and 4.58% respectively.

Hydrogenated TiO2 Thin Film for Accelerating Electron Transport in Highly Efficient Planar Perovskite Solar Cells.

Science.gov (United States)

Yao, Xin; Liang, Junhui; Li, Yuelong; Luo, Jingshan; Shi, Biao; Wei, Changchun; Zhang, Dekun; Li, Baozhang; Ding, Yi; Zhao, Ying; Zhang, Xiaodan

2017-10-01

Intensive studies on low-temperature deposited electron transport materials have been performed to improve the efficiency of n-i-p type planar perovskite solar cells to extend their application on plastic and multijunction device architectures. Here, a TiO 2 film with enhanced conductivity and tailored band edge is prepared by magnetron sputtering at room temperature by hydrogen doping (HTO), which accelerates the electron extraction from perovskite photoabsorber and reduces charge transfer resistance, resulting in an improved short circuit current density and fill factor. The HTO film with upward shifted Fermi level guarantees a smaller loss on V OC and facilitates the growth of high-quality absorber with much larger grains and more uniform size, leading to devices with negligible hysteresis. In comparison with the pristine TiO 2 prepared without hydrogen doping, the HTO-based device exhibits a substantial performance enhancement leading to an efficiency of 19.30% and more stabilized photovoltaic performance maintaining 93% of its initial value after 300 min continuous illumination in the glove box. These properties permit the room-temperature magnetron sputtered HTO film as a promising electron transport material for flexible and tandem perovskite solar cell in the future.

Influences of Mg Doping on the Electrochemical Performance of TiO2 Nanodots Based Biosensor Electrodes

Directory of Open Access Journals (Sweden)

M. S. H. Al-Furjan

2014-01-01

Full Text Available Electrochemical biosensors are essential for health monitors to help in diagnosis and detection of diseases. Enzyme adsorptions on biosensor electrodes and direct electron transfer between them have been recognized as key factors to affect biosensor performance. TiO2 has a good protein adsorption ability and facilitates having more enzyme adsorption and better electron transfer. In this work, Mg ions are introduced into TiO2 nanodots in order to further improve electrode performance because Mg ions are considered to have good affinity with proteins or enzymes. Mg doped TiO2 nanodots on Ti substrates were prepared by spin-coating and calcining. The effects of Mg doping on the nanodots morphology and performance of the electrodes were investigated. The density and size of TiO2 nanodots were obviously changed with Mg doping. The sensitivity of 2% Mg doped TiO2 nanodots based biosensor electrode increased to 1377.64 from 897.8 µA mM−1 cm−2 and its KMapp decreases to 0.83 from 1.27 mM, implying that the enzyme achieves higher catalytic efficiency due to better affinity of the enzyme with the Mg doped TiO2. The present work could provide an alternative to improve biosensor performances.

Production and Characterization of (004) Oriented Single Anatase TiO2 Films

Science.gov (United States)

Atay, Ferhunde; Akyuz, Idris; Cergel, Muge Soyleyici; Erdogan, Banu

2018-02-01

Highly (004) oriented anatase TiO2 films have been successfully obtained by an inexpensive ultrasonic spray pyrolysis technique at low substrate temperatures and without additional annealing. X-ray diffraction analysis, ultraviolet-visible spectroscopy and field emission scanning electron microscopy were used to analyze the structural, optical and surface properties of the films. By using the less reported TiCl4 solution, the optical band gap values falling into the visible region (between 2.70 eV and 2.92 eV) have been obtained for all films. Spectroscopic ellipsometry technique has been used to determine the dispersive refractive index and extinction coefficient of TiO2 films. Possible electrical conduction mechanisms in TiO2 films have been examined using temperature dependent conductivity measurements in the temperature range of 78-300 K. At room temperature, electrical resistivity values of TiO2 films change between 1.68 × 104 Ω cm and 5.88 × 104 Ω cm. Considering the analyzed parameters with respect to substrate temperature, this work refers to the properties of anatase TiO2 films that are strongly correlated to the growth direction, namely (004). As a result, (004) oriented anatase TiO2 films with appropriate optical band gap values are promising materials for technological applications, especially for photocatalysts.

Characterization and improved solar light activity of vanadium doped TiO2/diatomite hybrid catalysts.

Science.gov (United States)

Wang, Bin; Zhang, Guangxin; Leng, Xue; Sun, Zhiming; Zheng, Shuilin

2015-03-21

V-doped TiO2/diatomite composite photocatalysts with different vanadium concentrations were synthesized by a modified sol-gel method. The diatomite was responsible for the well dispersion of TiO2 nanoparticles on the matrix and consequently inhibited the agglomeration. V-TiO2/diatomite hybrids showed red shift in TiO2 absorption edge with enhanced absorption intensity. Most importantly, the dopant energy levels were formed in the TiO2 bandgap due to V(4+) ions substituted to Ti(4+) sites. The 0.5% V-TiO2/diatomite photocatalyst displayed narrower bandgap (2.95 eV) compared to undoped sample (3.13 eV) and other doped samples (3.05 eV) with higher doping concentration. The photocatalytic activities of V doped TiO2/diatomite samples for the degradation of Rhodamine B under stimulated solar light illumination were significantly improved compared with the undoped sample. In our case, V(4+) ions incorporated in TiO2 lattice were responsible for increased visible-light absorption and electron transfer to oxygen molecules adsorbed on the surface of TiO2 to produce superoxide radicals ˙O2(-), while V(5+) species presented on the surface of TiO2 particles in the form of V2O5 contributed to e(-)-h(+) separation. In addition, due to the combination of diatomite as support, this hybrid photocatalyst could be separated from solution quickly by natural settlement and exhibited good reusability. Copyright © 2014 Elsevier B.V. All rights reserved.

Unusual photoelectric behaviors of Mo-doped TiO2 multilayer thin films prepared by RF magnetron co-sputtering: effect of barrier tunneling on internal charge transfer

Science.gov (United States)

Yan, B. X.; Luo, S. Y.; Mao, X. G.; Shen, J.; Zhou, Q. F.

2013-01-01

Mo-doped TiO2 multilayer thin films were prepared by RF magnetron co-sputtering. Microstructures, crystallite parameters and the absorption band were investigated with atomic force microscopy, X-ray diffraction and ultraviolet-visible spectroscopy. Internal carrier transport characteristics and the photoelectric property of different layer-assemble modes were examined on an electrochemical workstation under visible light. The result indicates that the double-layer structure with an undoped surface layer demonstrated a red-shifted absorption edge and a much stronger photocurrent compared to the uniformly doped sample, signifying that the electric field implanted at the interface between particles in different layers accelerated internal charge transfer effectively. However, a heavily doped layer implanted at the bottom of the three-layer film merely brought about negative effects on the photoelectric property, mainly because of the Schottky junction existing above the substrate. Nevertheless, this obstacle was successfully eliminated by raising the Mo concentration to 1020 cm-3, where the thickness of the depletion layer fell into the order of angstroms and the tunneling coefficient manifested a dramatic increase. Under this circumstance, the Schottky junction disappeared and the strongest photocurrent was observed in the three-layer film.

A novel single-step synthesis of N-doped TiO2 via a sonochemical method

International Nuclear Information System (INIS)

Wang, Xi-Kui; Wang, Chen; Guo, Wei-Lin; Wang, Jin-Gang

2011-01-01

Graphical abstract: The N-doped anatase TiO 2 nanoparticles were synthesized by sonochemical method. The as-prepared sample is characterized by XRD, TEM, XPS and UV-Vis DRS. The photocatalytic activity of the photocatalyst was evaluated by the photodegradation of an azo dye direct sky blue 5B. Highlights: → A novel singal-step sonochemical synthesis method for the preparation of anatase N-doped TiO 2 nanocrystalline at low temperature has been devoleped. → The as-prepared sample is characterized by XRD, TEM, XPS and UV-Vis DRS. → The photodegradation of azo dye direct sky blue 5 showed that the N-doped TiO 2 catalyst is of high visible-light photocatalytic activity. -- Abstract: A novel single-step synthetic method for the preparation of anatase N-doped TiO 2 nanocrystalline at low temperature has been devoleped. The N-doped anatase TiO 2 nanoparticles were synthesized by sonication of the solution of tetraisopropyl titanium and urea in water and isopropyl alcohol at 80 o C for 150 min. The as-prepared sample was characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and UV-vis absorption spectrum. The product structure depends on the reaction temperature and reaction time. The photocatalytic activity of the as-prepared photocatalyst was evaluated via the photodegradation of an azo dye direct sky blue 5B. The results show that the N-doped TiO 2 nanocrystalline prepared via sonication exhibit an excellent photocatalytic activity under UV light and simulated sunlight.

Preparation and characterization of doped TiO2 nanofibers by coaxial electrospining combined with sol–gel process

International Nuclear Information System (INIS)

Tong, Haixia; Tao, Xican; Wu, Daoxin; Zhang, Xiongfei; Li, Dan; Zhang, Ling

2014-01-01

Graphical abstract: The surface of the precursor of Fe/TiO 2 nanofibers are smoother than that of Fe /TiO 2 nanofibers. After calcined at 500 °C, the tubers on the surface of the nanofibers become more obvious, and which also provides a direct proof for the dopant of Fe element. -- Highlights: • N, Fe, and W doped TiO 2 nanofibers have been fabricated by coaxial electrospining. • The dopant has obvious influences on the surface topographies and crystal structures. • Fe doping can make remarkable topography changes and easy formation of rutile TiO 2 . • The maximum doping amount of W in TiO 2 nanofibers is less than 10% under 500 °C. -- Abstract: N, Fe, and W doped TiO 2 nanofibers were fabricated by coaxial electrospining and directly annealing polyvinylpyrrolidone (PVP)/Tetrabutyl titanate (TBT) composite nanofibers. The crystal structure, morphology, and surface composition of the doped TiO 2 nanofibers were investigated by the X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) respectively. The results show that the dopants have different influence on the surface topographies, the crystal structures and the transformation of anatase to rutile of TiO 2 nanofibers. Fe dopant promotes bigger influence on topographies, phase transformation and crystallite growth of TiO 2 nanofibers than that of either N or W dopant

Electrochemical reduction induced self-doping of Ti3+ for efficient water splitting performance on TiO2 based photoelectrodes

KAUST Repository

Zhang, Zhonghai

2013-01-01

Hetero-element doping (e.g., N, F, C) of TiO2 is inevitably accompanied by significantly increased structural defects due to the dopants\\' nature being foreign impurities. Very recently, in situ self-doping with homo-species (e.g., Ti3+) has been emerging as a rational solution to enhance TiO2 photoactivity within both UV and visible light regions. Herein we demonstrate that conventional electrochemical reduction is indeed a facile and effective strategy to induce in situ self-doping of Ti3+ into TiO2 and the self-doped TiO2 photoelectrodes showed remarkably improved and very stable water splitting performance. In this study, hierarchical TiO2 nanotube arrays (TiO2 NTs) were chosen as TiO2 substrates and then electrochemically reduced under varying conditions to produce Ti3+ self-doped TiO2 NTs (ECR-TiO2 NTs). The optimized saturation photocurrent density and photoconversion efficiency on the ECR-TiO2 NTs under simulated AM 1.5G illumination were identified to be 2.8 mA cm-2 at 1.23 V vs. RHE and 1.27% respectively, which are the highest values ever reported for TiO 2 based photoelectrodes. The electrochemical impedance spectra measurement confirms that the electrochemical induced Ti3+ self-doping improved the electrical conductivity of the ECR-TiO2 NTs. The versatility and effectiveness of the electrochemical reduction method for Ti3+ self-doping in P25 based TiO2 was also examined and confirmed. This journal is © 2013 the Owner Societies.

Enhancement of Perovskite Solar Cells Efficiency using N-Doped TiO2 Nanorod Arrays as Electron Transfer Layer.

Science.gov (United States)

Zhang, Zhen-Long; Li, Jun-Feng; Wang, Xiao-Li; Qin, Jian-Qiang; Shi, Wen-Jia; Liu, Yue-Feng; Gao, Hui-Ping; Mao, Yan-Li

2017-12-01

In this paper, N-doped TiO 2 (N-TiO 2 ) nanorod arrays were synthesized with hydrothermal method, and perovskite solar cells were fabricated using them as electron transfer layer. The solar cell performance was optimized by changing the N doping contents. The power conversion efficiency of solar cells based on N-TiO 2 with the N doping content of 1% (N/Ti, atomic ratio) has been achieved 11.1%, which was 14.7% higher than that of solar cells based on un-doped TiO 2 . To get an insight into the improvement, some investigations were performed. The structure was examined with X-ray powder diffraction (XRD), and morphology was examined by scanning electron microscopy (SEM). Energy dispersive spectrometer (EDS) and Tauc plot spectra indicated the incorporation of N in TiO 2 nanorods. Absorption spectra showed higher absorption of visible light for N-TiO 2 than un-doped TiO 2 . The N doping reduced the energy band gap from 3.03 to 2.74 eV. The photoluminescence (PL) and time-resolved photoluminescence (TRPL) spectra displayed the faster electron transfer from perovskite layer to N-TiO 2 than to un-doped TiO 2 . Electrochemical impedance spectroscopy (EIS) showed the smaller resistance of device based on N-TiO 2 than that on un-doped TiO 2 .

Intrinsic Photocatalytic Assessment of Reactively Sputtered TiO2 Films

NARCIS (Netherlands)

Rafieian Boroujeni, Damon; Driessen, Rick Theodorus; Driessen, Rick T.; Ogieglo, Wojciech; Lammertink, Rob G.H.

2015-01-01

Thin TiO2 films were prepared by DC magnetron reactive sputtering at different oxygen partial pressures. Depending on the oxygen partial pressure during sputtering, a transition from metallic Ti to TiO2 was identified by spectroscopic ellipsometry. The crystalline nature of the film developed during

Performance enhancement of perovskite solar cells with Mg-doped TiO2 compact film as the hole-blocking layer

International Nuclear Information System (INIS)

Wang, Jing; Qin, Minchao; Tao, Hong; Ke, Weijun; Chen, Zhao; Wan, Jiawei; Qin, Pingli; Lei, Hongwei; Fang, Guojia; Xiong, Liangbin; Yu, Huaqing

2015-01-01

In this letter, we report perovskite solar cells with thin dense Mg-doped TiO 2 as hole-blocking layers (HBLs), which outperform cells using TiO 2 HBLs in several ways: higher open-circuit voltage (V oc ) (1.08 V), power conversion efficiency (12.28%), short-circuit current, and fill factor. These properties improvements are attributed to the better properties of Mg-modulated TiO 2 as compared to TiO 2 such as better optical transmission properties, upshifted conduction band minimum (CBM) and downshifted valence band maximum (VBM), better hole-blocking effect, and higher electron life time. The higher-lying CBM due to the modulation with wider band gap MgO and the formation of magnesium oxide and magnesium hydroxides together resulted in an increment of V oc . In addition, the Mg-modulated TiO 2 with lower VBM played a better role in the hole-blocking. The HBL with modulated band position provided better electron transport and hole blocking effects within the device

Preparation and characterization of nanocrystalline porous TiO2/WO3 composite thin films

International Nuclear Information System (INIS)

Hsu, C.-S.; Lin, C.-K.; Chan, C.-C.; Chang, C.-C.; Tsay, C.-Y.

2006-01-01

TiO 2 materials possessing not only photocatalytic but also electrochromic properties have attracted many research and development interests. Though WO 3 exhibits excellent electrochromic properties, the much higher cost and water-sensitivity of WO 3 as compared with the TiO 2 may restrict the practical application of WO 3 materials. In the present study, the feasibility of preparing nanocrystalline porous TiO 2 /WO 3 composite thin films was investigated. Precursors of sols TiO 2 and/or WO 3 and polystyrene microspheres were used to prepare nanocrystalline pure TiO 2 , WO 3 , and composite TiO 2 /WO 3 thin films by spin coating. The spin-coated thin films were amorphous and, after heat treating at a temperature of 500 o C, nanocrystalline TiO 2 , TiO 2 /WO 3 , and WO 3 thin films with or without pores were prepared successfully. The heat-treated thin films were colorless and coloration-bleaching phenomena can be observed during cyclic voltammetry tests. The heat-treated thin films exhibited good reversible electrochromic behavior while the porous TiO 2 /WO 3 composite film exhibited improved electrochromic properties

Synthesis and characterization of TiO2 photocatalyst doped by transition metal ions (Fe3+, Cr3+ and V5+)

International Nuclear Information System (INIS)

Tuan Vu, Anh; Linh Bui, Thi Hai; Cuong Tran, Manh; Phuong Dang, Tuyet; Hoa Tran, Thi Kim; Tuan Nguyen, Quoc

2010-01-01

Nano TiO 2 was synthesized by the hydrothermal method. The sample was doped with transition metal ions (V, Cr and Fe) and non-metal (N). Doped TiO 2 samples were characterized by x-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and UV-Vis diffuse reflectance spectroscopy (UV-Vis). Photocatalytic activity in the mineralization of xylene (vapor phase), methylene blue and active dyer PR (liquid phase) was tested. In comparison with non-doped TiO 2 , V-, Cr-, Fe-doped TiO 2 and N-doped TiO 2 samples exhibited much higher photocatalytic activity using visible light instead of UV

An efficient visible and UV-light-activated B–N-codoped TiO2 photocatalytic film for solar depollution prepared via a green method

International Nuclear Information System (INIS)

Xu Qingchi; Zhang Yan; He Ziming; Loo, Say Chye Joachim; Tan, Timothy Thatt Yang

2012-01-01

This work reports an efficient visible and UV-light-activated boron and nitrogen codoped TiO 2 porous film prepared via a “green” and direct coating approach. Such photocatalyst is highly promising for solar depollution application due to its efficient photocatalytic activities in both visible and UV spectrum. The preparation method avoids the use of organic solvents, which are usually more expensive and hazardous compared with water. Using stearic acid as the model organic pollutant, the visible-light photocatalytic activity of optimized porous B–N-codoped TiO 2 film (p-3B–N–TiO 2 ) is 3 times higher than that of porous N-doped TiO 2 (p-N–TiO 2 ) film, while its UV photocatalytic activity is almost double that of p-N–TiO 2 film and comparable to that of porous TiO 2 . The enhancement in photocatalytic activity is attributed to higher surface area due to the porous structure, improved visible-light absorption attributed to interstitially substituted boron atoms, and coexistence of boron and nitrogen dopants which may reduce Ti 3+ recombination centers.

Synthesis of nanocrystalline TiO2 thin films by liquid phase ...

Indian Academy of Sciences (India)

WINTEC

goes degradation efficiently in presence of TiO2 thin films by exposing its aqueous solution to .... Figure 6. Photodegradation of IGOR organic dye by a. bare TiO2 thin film and b. ... Meng L-J and Dos Santos M P 1993 Thin Solid Films 226 22.

Enhanced photocatalytic activity for H2 evolution under irradiation of UV-vis light by Au-modified nitrogen-doped TiO2.

Science.gov (United States)

Zhao, Weirong; Ai, Zhuyu; Dai, Jiusong; Zhang, Meng

2014-01-01

Photocatalytic water splitting for hydrogen evolution is a potential way to solve many energy and environmental issues. Developing visible-light-active photocatalysts to efficiently utilize sunlight and finding proper ways to improve photocatalytic activity for H2 evolution have always been hot topics for research. This study attempts to expand the use of sunlight and to enhance the photocatalytic activity of TiO2 by N doping and Au loading. Au/N-doped TiO2 photocatalysts were synthesized and successfully used for photocatalytic water splitting for H2 evolution under irradiation of UV and UV-vis light, respectively. The samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), and photoelectrochemical characterizations. DRS displayed an extension of light absorption into the visible region by doping of N and depositing with Au, respectively. PL analysis indicated electron-hole recombination due to N doping and an efficient inhibition of electron-hole recombination due to the loaded Au particles. Under the irradiation of UV light, the photocatalytic hydrogen production rate of the as-synthesized samples followed the order Au/TiO2 > Au/N-doped TiO2 > TiO2 > N-doped TiO2. While under irradiation of UV-vis light, the N-TiO2 and Au/N-TiO2 samples show higher H2 evolution than their corresponding nitrogen-free samples (TiO2 and Au/TiO2). This inconsistent result could be attributed to the doping of N and the surface plasmonic resonance (SPR) effect of Au particles extending the visible light absorption. The photoelectrochemical characterizations further indicated the enhancement of the visible light response of Au/N-doped TiO2. Comparative studies have shown that a combination of nitrogen doping and Au loading enhanced the visible light response of TiO2 and increased the utilization of solar energy, greatly

Enhanced photocatalytic activity for H2 evolution under irradiation of UV-vis light by Au-modified nitrogen-doped TiO2.

Directory of Open Access Journals (Sweden)

Weirong Zhao

Full Text Available BACKGROUND PURPOSE: Photocatalytic water splitting for hydrogen evolution is a potential way to solve many energy and environmental issues. Developing visible-light-active photocatalysts to efficiently utilize sunlight and finding proper ways to improve photocatalytic activity for H2 evolution have always been hot topics for research. This study attempts to expand the use of sunlight and to enhance the photocatalytic activity of TiO2 by N doping and Au loading. METHODS: Au/N-doped TiO2 photocatalysts were synthesized and successfully used for photocatalytic water splitting for H2 evolution under irradiation of UV and UV-vis light, respectively. The samples were characterized using X-ray diffraction (XRD, transmission electron microscopy (TEM, X-ray photoelectron spectroscopy (XPS, UV-vis diffuse reflectance spectroscopy (DRS, photoluminescence spectroscopy (PL, and photoelectrochemical characterizations. RESULTS: DRS displayed an extension of light absorption into the visible region by doping of N and depositing with Au, respectively. PL analysis indicated electron-hole recombination due to N doping and an efficient inhibition of electron-hole recombination due to the loaded Au particles. Under the irradiation of UV light, the photocatalytic hydrogen production rate of the as-synthesized samples followed the order Au/TiO2 > Au/N-doped TiO2 > TiO2 > N-doped TiO2. While under irradiation of UV-vis light, the N-TiO2 and Au/N-TiO2 samples show higher H2 evolution than their corresponding nitrogen-free samples (TiO2 and Au/TiO2. This inconsistent result could be attributed to the doping of N and the surface plasmonic resonance (SPR effect of Au particles extending the visible light absorption. The photoelectrochemical characterizations further indicated the enhancement of the visible light response of Au/N-doped TiO2. CONCLUSION: Comparative studies have shown that a combination of nitrogen doping and Au loading enhanced the visible light response of

Synthesis, characterization, and analysis of enhanced photocatalytic activity of Zr-doped TiO2 nanostructured powders under UV light

Science.gov (United States)

Sekhar, M. Chandra; Purusottam Reddy, B.; Mallikarjuna, K.; Shanmugam, Gnanendra; Ahn, Chang-Hoi; Park, Si-Hyun

2018-01-01

Zr-doped and pure TiO2 nanoparticles (NPs) were synthesized using a simple inexpensive sol-gel method. X-ray powder diffractometry and Fourier transform infrared spectrometry revealed the presence of anatase-phase TiO2 NPs. Scanning electron microscopy and transmission electron microscopy revealed that the average nanocrystalline size of approximately 15 nm. The photocatalytic activities of these materials were evaluated using Rhodamine B (Rh B) as an organic contaminant. The photocatalytic activity of pure and Zr-doped TiO2 NPs (with at% 4, 8, 12 and 16) was measured in terms of the degradation of Rh B under UV light. The antibacterial activities of pure and Zr-doped (with 8 at%) TiO2 NPs were evaluated against Bacillus subtillis, Escherichia coli, and Pseudomonas aeruginosa. A maximum inhibition zone (19 mm) was observed for pure TiO2 NPs, against Bacillus subtillis and Pseudomonas aeruginosa, while Zr-doped TiO2 (8 at%) exhibited a lesser inhibition zone (18 mm) against the same Bacillus subtillis and Pseudomonas aeruginosa (18 mm). However, Zr-doped TiO2 (8 at%) NPs exhibited a greater inhibition zone against Escherichia coli (17 mm), while the activity of pure TiO2 NPs against Escherichia coli (15 mm) was retarded. Thus, pure TiO2 NPs and Zr-doped TiO2 (8 at%) NPs have competent activities and can be used as antibacterial agents against different bacteria.

Enhanced visible light photocatalytic properties of Fe-doped TiO2 nanorod clusters and monodispersed nanoparticles

International Nuclear Information System (INIS)

Liu, Y.; Wei, J.H.; Xiong, R.; Pan, C.X.; Shi, J.

2011-01-01

In order to get photocatalysts with desired morphologies and enhanced visible light responses, the Fe-doped TiO 2 nanorod clusters and monodispersed nanoparticles were prepared by modified hydrothermal and solvothermal method, respectively. The microstructures and morphologies of TiO 2 crystals can be controlled by restraining the hydrolytic reaction rates. The Fe-doped photocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis absorption spectroscopy (UV-vis), N 2 adsorption-desorption measurement (BET), and photoluminescence spectroscopy (PL). The refinements of the microstructures and morphologies result in the enhancement of the specific surface areas. The Fe 3+ -dopants in TiO 2 lattices not only lead to the significantly extending of the optical responses from UV to visible region but also diminish the recombination rates of the electrons and holes. The photocatalytic activities were evaluated by photocatalytic decomposition of formaldehyde in air under visible light illumination. Compared with P25 (TiO 2 ) and N-doped TiO 2 nanoparticles, the Fe-doped photocatalysts show high photocatalytic activities under visible light.

The investigation of photo-induced chemiluminescence on Co2+-doped TiO2 nanoparticles and its analytical application.

Science.gov (United States)

Li, Guixin; Nan, Hongyan; Zheng, Xingwang

2009-07-01

A novel space- and time-resolved photo-induced chemiluminescence (PICL) analytical method was developed based on the photocatalysis of the Co2+-doped TiO2 nanoparticles. The PICL reaction procedure under the photocatalysis of Co2+-doped TiO2 nanoparticles was investigated using cyclic voltammetry and potentiometry. Meanwhile, the effect of the electrical double layer outside the Co2+-doped TiO2 nanoparticles on the PICL was investigated by contrasting with the Co2+-doped TiO2-SiO2 core-shell nanoparticles. Significantly, the CL intensity increased apparently and the time of the CL was prolonged in the presence of procaterol hydrochloride because the mechanism of the enhanced PICL reaction may be modified. The route of the PICL was changed due to the participation of the procaterol hydrochloride enriched at the surface of the Co2+-doped TiO2-SiO2 in the PICL reaction, which prolonged the time of the CL reaction and resulted in the long-term PICL. The analytical characteristics of the proposed in-situ PICL method were investigated using the procaterol hydrochloride as the model analyte. The investigation results showed that this new PICL analytical method offered higher sensitivity to the analysis of the procaterol hydrochloride and the PICL intensity was linear with the concentration of the procaterol hydrochloride in the range from ca. 2.0 x 10(-10) to 1.0 x 10(-8) g mL(-1).

Tailoring optical properties of TiO2-Cr co-sputtered films using swift heavy ions

Science.gov (United States)

Gupta, Ratnesh; Sen, Sagar; Phase, D. M.; Avasthi, D. K.; Gupta, Ajay

2018-05-01

Effect of 100 MeV Au7+ ion irradiation on structure and optical properties of Cr-doped TiO2 films has been studied using X-ray photoelectron spectroscopy, soft X-ray absorption spectroscopy, UV-Visible spectroscopy, X-ray reflectivity, and atomic force microscopy. X-ray reflectivity measurement implied that film thickness reduces as a function of ion fluence while surface roughness increases. The variation in surface roughness is well correlated with AFM results. Ion irradiation decreases the band gap energy of the film. Swift heavy ion irradiation enhances the oxygen vacancies in the film, and the extra electrons in the vacancies act as donor-like states. In valence band spectrum, there is a shift in the Ti3d peak towards lower energies and the shift is equivalent to the band gap energy obtained from UV spectrum. Evidence for band bending is also provided by the corresponding Ti XPS peak which exhibits a shift towards lower energy due to the downward band bending. X-ray absorption studies on O Kand Cr L3,2 edges clearly indicate that swift heavy ion irradiation induces formation of Cr-clusters in TiO2 matrix.

Microwave-assisted self-doping of TiO2 photonic crystals for efficient photoelectrochemical water splitting

KAUST Repository

Zhang, Zhonghai; Yang, Xiulin; Hedhili, Mohamed N.; Ahmed, Elaf S.; Shi, Le; Wang, Peng

2014-01-01

In this article, we report that the combination of microwave heating and ethylene glycol, a mild reducing agent, can induce Ti3+ self-doping in TiO2. A hierarchical TiO2 nanotube array with the top layer serving as TiO2 photonic crystals (TiO2 NTPCs

TiO2 nanotube formation by Ti film anodization and their transport properties for dye-sensitized solar cells

NARCIS (Netherlands)

Iraj, M.; Kolahdouz, M.; Asl-Soleimani, E.; Esmaeili, E.; Kolahdouz Esfahani, Z.

2016-01-01

In this paper, we present the synthesis of TiO2 nanotube (NT) arrays formed by anodization of Ti film deposited on a fluorine-doped tin oxide-coated glass substrate by direct current magnetron sputtering. NH4F/ethylene glycol electrolyte was used to demonstrate the growth of stable nanotubes at room

Effect of Sr doping on LaTiO3 thin films

International Nuclear Information System (INIS)

Vilquin, B.; Kanki, T.; Yanagida, T.; Tanaka, H.; Kawai, T.

2005-01-01

We report on the electric properties of La 1-x Sr x TiO 3 (0 ≤ x ≤ 0.5) thin films fabricated by pulsed laser deposition method. Crystallographic measurement of the thin films showed the epitaxial c-axis perovskite structure. The electric property of LaTiO 3 thin film, which is a typical Mott insulative material in bulk, showed insulative behaviour, while the Sr-doped films showed metallic conduction suffering electron-electron scattering. Below x = 0.1, the major carrier type was identified to be hole, and switched to electron with further increasing Sr-doping above x = 0.15. In fact, the switching from p-type to n-type for La 1-x Sr x TiO 3 thin films is first demonstrated in this study. The transition suggests that effective Coulomb gap vanishes due to over-additional Sr doping

Corrosion protection of AISI 1018 steel using Co-doped TiO_2/polypyrrole nanocomposites in 3.5% NaCl solution

International Nuclear Information System (INIS)

Ladan, Magaji; Basirun, Wan Jeffrey; Kazi, Salim Newaz; Rahman, Fariza Abdul

2017-01-01

A polypyrrole nanocomposites (PPy NTCs) have been effectively synthesized in the presence of TiO_2 and Co-doped TiO_2 nanoparticles (NPs) by an in situ chemical oxidative polymerization. Field Emission Scanning Electron Microscopy and Transmission Electron Microscopy revealed a tube shape structure of the PPy. The TEM results confirmed that the nanocomposite size of Co-doped TiO_2/PPy NTCs was smaller than TiO_2/PPy NTCs thereby increasing the interaction between the PPy nanotube and the AISI steel surface. The corrosion performance of the coatings was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements in 3.5% NaCl solution. The EIS results show that the log |Z| of AISI 1018 coated with Co-doped TiO_2/PPy NTCs and TiO_2/PPy NTCs reached about 8.2 and 6.0 respectively after 30 days of exposure in 3.5% NaCl solution. This is likely due to the increased surface area of the PPy synthesized in the presence of Co-doped TiO_2 NPs. The EIS results are confirmed by the potentiodynamic polarization and open circuit potential values of the Co-doped TiO_2/PPy which indicated little changes between 1 and 30 days of exposure which confirms the protection ability of this coating. . It is evident that the presence of Co-doped TiO_2 NPs can enhance the resistance against corrosion at the steel/electrolyte interface. - Highlights: • Polymerization of pyrrole monomer in the presence of Co-doped TiO_2 decreases the size of the polypyrrole nanotube (PPy NT). • The corrosion protection increases with the increase in PPy NT dispersion. • The corrosion resistance of steel coated with Co-doped TiO_2/PPy NTCs is considerably higher. • TiO_2/PPy with Co doping reduces the charge transfer across the electrolyte/AISI 1018 steel interface.

TiO2 thin-films on polymer substrates and their photocatalytic activity

International Nuclear Information System (INIS)

Yang, Jae-Hun; Han, Yang-Su; Choy, Jin-Ho

2006-01-01

We have developed dip-coating process for TiO 2 -thin film on polymer substrates (acrylonitrile-butadiene-styrene polymer: ABS, polystyrene: PS). At first, a monodispersed and transparent TiO 2 nano-sol solution was prepared by the controlled hydrolysis of titanium iso-propoxide in the presence of acetylacetone and nitric acid catalyst at 80 deg. C. Powder X-ray diffraction patterns of the dried particles are indicative of crystalline TiO 2 with anatase-type structure. According to the XRD and transmission electron microscopy (TEM) studies, the mean particle size was estimated to be ca. 5 nm. The transparent thin films on ABS and PS substrates were fabricated by dip-coating process by changing the processing variables, such as the number of dip-coating and TiO 2 concentration in nano-sol solution. Scanning electron microscopic (SEM) analysis for the thin film samples reveals that the acetylacetone-modified TiO 2 nano-sol particles are effective for enhancing the interfacial adherence between films and polymeric substrates compared to the unmodified one. Photocatalytic degradation of methylene blue (MB) on the TiO 2 thin-films has also been systematically investigated

Synergistic Effect of Fluorinated and N Doped TiO2 Nanoparticles Leading to Different Microstructure and Enhanced Photocatalytic Bacterial Inactivation

Directory of Open Access Journals (Sweden)

Irena Milosevic

2017-11-01

Full Text Available This work focuses on the development of a facile and scalable wet milling method followed by heat treatment to prepare fluorinated and/or N-doped TiO2 nanopowders with improved photocatalytic properties under visible light. The structural and electronic properties of doped particles were investigated by various techniques. The successful doping of TiO2 was confirmed by X-ray photoelectron spectroscopy (XPS, and the atoms appeared to be mainly located in interstitial positions for N whereas the fluorination is located at the TiO2 surface. The formation of intragap states was found to be responsible for the band gap narrowing leading to the faster bacterial inactivation dynamics observed for the fluorinated and N doped TiO2 particles compared to N-doped TiO2. This was attributed to a synergistic effect. The results presented in this study confirmed the suitability of the preparation approach for the large-scale production of cost-efficient doped TiO2 for effective bacterial inactivation.

Synthesis of two-dimensional nanowall of Cu-Doped TiO2 and its application as photoanode in DSSCs

Science.gov (United States)

Dahlan, Dahyunir; Md Saad, Siti Khatijah; Berli, Ade Usra; Bajili, Abdil; Umar, Akrajas Ali

2017-07-01

Two-dimensional nanowall of Cu-doped TiO2 (CuTNW) has been prepared in this work to study the role of Cu doping on its photoactivity properties and its photovoltaic performance as photoanode in a dye-sensitized solar cell (DSSC). TiO2 nanowall with five Cu ion doping, i.e. 6.25, 12.5, 25.0, 50.0 and 100.0 mM, were prepared via a liquid-phase deposition method using ammoniumhexafluorotitanate and hexamethylenetetramine as the reagents with a growth temperature of 90 °C. The X-Ray Diffraction (XRD), X-ray energy dispersion (EDX) and diffuse optical reflectance spectroscopy analysis results confirmed the successfulness of the Cu doping process in the TiO2 nanowall and effective modification on the photoactivity of the TiO2 nanowall. We found that the power conversion efficiency of the DSSC utilizing TiO2 nanowall as photoanode can be enhanced up to 2 times, i.e. from 0.2% to 0.44%, when the TiO2 nanowall doped with Cu ion. The nanostructure preparation, device fabrication and the mechanism for the device performance enhancement will be discussed.

A comparative study of the magnetization in transition metal ion doped CeO2, TiO2 and SnO2 nanoparticles

Science.gov (United States)

Apostolov, A. T.; Apostolova, I. N.; Wesselinowa, J. M.

2018-05-01

Using the microscopic s-d model taking into account anharmonic spin-phonon interactions we have studied the magnetic properties of Co and Cu ion doped CeO2 and TiO2 nanoparticles and compared them with those of SnO2. By Co-doping there is a maximum in the magnetization M(x) curve for all nanoparticles observed in the most transition metal doped ones. The s-d interaction plays an important role by the decrease of M at higher dopant concentration. We have discussed the magnetization in dependence of different model parameters. By small Cu-ion doping there are some differences. In CeO2M decreases with the Cu-concentration, whereas in TiO2 and SnO2M increases. For higher Cu dopant concentrations M(X) decreases in TiO2 nanoparticles. We obtain room temperature ferromagnetism also in Zn doped CeO2, TiO2 and SnO2 nanoparticles, i.e. in non-transition metal ion doped ones. The different behavior of M in Co and Cu doped nanoparticles is due to a combination effect of multivalent metal ions, oxygen vacancies, different radius of cation dopants, connection between lattice and magnetism, as well as competition between the s-d and d-d ferromagnetic or antiferromagnetic interactions.

Synthesis and characterization of Fe-doped TiO2 photocatalyst by the sol–gel method

International Nuclear Information System (INIS)

Luu, Cam Loc; Ho, Si Thoang; Nguyen, Quoc Tuan

2010-01-01

Thin layers of pure TiO 2 and TiO 2 doped by different amounts of Fe 2 O 3 have been prepared by the sol–gel method with tetraisopropyl orthotitanate and Fe(NO 3 ) 3 . Physico-chemical properties of catalysts were characterized by BET Adsorption, x-ray Diffraction (XRD), FE-SEM, as well as Raman and UV-Vis spectroscopy. The photocatalytic activity of the obtained materials was investigated in the reaction of complete oxidation of p-xylene in gas phase under the radiation of UV (λ=365 nm) and LED (λ=470 nm) lamps. It has been found that the particle size of all samples was distributed in the range 20–30 nm. The content of the rutile phase in Fe-doped TiO 2 samples varied in the range 6.8 to 41.8% depending on the Fe content. Iron oxide doped into TiO 2 enables the photon absorbing zone of TiO 2 to extend from UV towards visible waves as well as to reduce its band gap energy from 3.2 to 2.67 eV. Photocatalytic activities of the TiO 2 samples modified by Fe 3+ have been found to be higher than those of pure TiO 2 by about 2.5 times

Photocatalytic activity of Sulfer-doped TiO2 fiber under visible light illumination (Joint research)

International Nuclear Information System (INIS)

Takeyama, Akinori; Yamamoto, Shunya; Yoshikawa, Masahito; Hasegawa, Yoshio; Awatsu, Satoshi

2007-03-01

The Sol-Gel derived precursor fiber was annealed under hydrogen disulfeid (H 2 S) following oxygen atmosphere, Sulfur-doped TiO 2 fiber was obtained. Crystal structure of the fiber was identified as anatase phase of TiO 2 . The energy band gap of the fiber was narrower by about 0.06 eV than that of anatase, which showed that it could absorb visible light. The fiber contains about 0.58 atomic % of Sulfur, and they located at the oxygen lattice site of TiO 2 . Under visible light illumination, the fiber degraded Trichloroethylen (TCE) and produced carbon dioxide (CO 2 ). This shows Sulfur-doped TiO 2 fiber has the photocatalytic activity under visible light illumination. (author)

Anomalous behavior of B1g mode in highly transparent anatase nano-crystalline Nb-doped Titanium Dioxide (NTO thin films

Directory of Open Access Journals (Sweden)

Subodh K. Gautam

2015-12-01

Full Text Available The effect of Niobium doping and size of crystallites on highly transparent nano-crystalline Niobium doped Titanium Dioxide (NTO thin films with stable anatase phase are reported. The Nb doping concentration is varied within the solubility limit in TiO2 lattice. Films were annealed in controlled environment for improving the crystallinity and size of crystallites. Elemental and thickness analysis were carried out using Rutherford backscattering spectrometry and cross sectional field emission scanning electron microscopy. Structural characteristics reveal a substitutional incorporation of Nb+5 in the TiO2 lattice which inhibits the anatase crystallites growth with increasing the doping percentage. The micro-Raman (MR spectra of films with small size crystallites shows stiffening of about 4 cm−1 for the Eg(1 mode and is ascribed to phonon confinement and non-stoichiometry. In contrast, B1g mode exhibits a large anomalous softening of 20 cm−1 with asymmetrical broadening; which was not reported for the case of pure TiO2 crystallites. This anomalous behaviour is explained by contraction of the apical Ti-O bonds at the surface upon substitutional Nb5+ doping induced reduction of Ti4+ ions also known as hetero-coordination effect. The proposed hypotheses is manifested through studying the electronic structure and phonon dynamics by performing the near edge x-ray absorption fine structure (NEXAFS and temperature dependent MR down to liquid nitrogen temperature on pure and 2.5 at.% doped NTO films, respectively.

PAMAM templated N,Pt co-doped TiO2 for visible light photodegradation of brilliant black.

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Nzaba, Sarre Kadia Myra; Ntsendwana, Bulelwa; Mamba, Bhekie Brilliance; Kuvarega, Alex Tawanda

2018-05-01

This study examined the photocatalytic degradation of an azo dye brilliant black (BB) using non-metal/metal co-doped TiO 2 . N,Pt co-doped TiO 2 photocatalysts were prepared by a modified sol-gel method using amine-terminated polyamidoamine dendrimer generation 0 (PG0) as a template and source of nitrogen. Structural, morphological, and textural properties were evaluated using scanning electron microscopy coupled to energy-dispersive X-ray spectroscopy (SEM/EDX), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), thermal gravimetric analysis (TGA), Fourier transform infrared (FTIR), Raman spectroscopy (RS), photoluminescence (PL) and ultra-violet/visible spectroscopy (UV-Vis). The synthesized photocatalysts exhibited lower band gap energies as compared to the Degussa P-25, revealing a red shift in band gap towards the visible light absorption region. Photocatalytic activity of N,Pt co-doped TiO 2 was measured by the reaction of photocatalytic degradation of BB dye. Enhanced photodegradation efficiency of BB was achieved after 180-min reaction time with an initial concentration of 50 ppm. This was attributed to the rod-like shape of the materials, larger surface area, and enhanced absorption of visible light induced by N,Pt co-doping. The N,Pt co-doped TiO 2 also exhibited pseudo-first-order kinetic behavior with half-life and rate constant of 0.37 and 0.01984 min -1 , respectively. The mechanism of the photodegradation of BB under the visible light irradiation was proposed. The obtained results prove that co-doping of TiO 2 with N and Pt contributed to the enhanced photocatalytic performances of TiO 2 for visible light-induced photodegradation of organic contaminants for environmental remediation. Therefore, this work provides a new approach to the synthesis of PAMAM templated N,Pt co-doped TiO 2 for visible light photodegradation of brilliant black.

The properties of transparent TiO2 films for Schottky photodetector

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Sung-Ho Park

2017-08-01

Full Text Available In this data, the properties of transparent TiO2 film for Schottky photodetector are presented for the research article, entitled as “High-performing transparent photodetectors based on Schottky contacts” (Patel et al., 2017 [1]. The transparent photoelectric device was demonstrated by using various Schottky metals, such as Cu, Mo and Ni. This article mainly shows the optical transmittance of the Ni-transparent Schottky photodetector, analyzed by the energy dispersive spectroscopy and interfacial TEM images for transparency to observe the interface between NiO and TiO2 film. The observation and analyses clearly show that no pinhole formation in the TiO2 film by Ni diffusion. The rapid thermal process is an effective way to form the quality TiO2 film formation without degradation, such as pinholes (Qiu et al., 2015 [2]. This thermal process may apply to form functional metal oxide layers for solar cells and photodetectors.

Ultrasound assisted synthesis of iron doped TiO2 catalyst.

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Ambati, Rohini; Gogate, Parag R

2018-01-01

The present work deals with synthesis of Fe (III) doped TiO 2 catalyst using the ultrasound assisted approach and conventional sol-gel approach with an objective of establishing the process intensification benefits. Effect of operating parameters such as Fe doping, type of solvent, solvent to precursor ratio and initial temperature has been investigated to get the best catalyst with minimum particle size. Comparison of the catalysts obtained using the conventional and ultrasound assisted approach under the optimized conditions has been performed using the characterization techniques like DLS, XRD, BET, SEM, EDS, TEM, FTIR and UV-Vis band gap analysis. It was established that catalyst synthesized by ultrasound assisted approach under optimized conditions of 0.4mol% doping, irradiation time of 60min, propan-2-ol as the solvent with the solvent to precursor ratio as 10 and initial temperature of 30°C was the best one with minimum particle size as 99nm and surface area as 49.41m 2 /g. SEM analysis, XRD analysis as well as the TEM analysis also confirmed the superiority of the catalyst obtained using ultrasound assisted approach as compared to the conventional approach. EDS analysis also confirmed the presence of 4.05mol% of Fe element in the sample of 0.4mol% iron doped TiO 2 . UV-Vis band gap results showed the reduction in band gap from 3.2eV to 2.9eV. Photocatalytic experiments performed to check the activity also confirmed that ultrasonically synthesized Fe doped TiO 2 catalyst resulted in a higher degradation of Acid Blue 80 as 38% while the conventionally synthesized catalyst resulted in a degradation of 31.1%. Overall, the work has clearly established importance of ultrasound in giving better catalyst characteristics as well as activity for degradation of the Acid Blue 80 dye. Copyright © 2017 Elsevier B.V. All rights reserved.

The effects of antimony doping on the surface structure of rutile TiO2(110)

International Nuclear Information System (INIS)

Bechstein, Ralf; Schuette, Jens; Kuehnle, Angelika; Kitta, Mitsunori; Onishi, Hiroshi

2009-01-01

Titanium dioxide represents a very important wide bandgap photocatalyst that is known to be sensitized to visible light by transition metal doping. Antimony doping has been demonstrated to provide photocatalytic activity when codoped with chromium at an optimum dopant ratio [Sb]/[Cr] of about 1.5. Here, the role of antimony doping on the surface structure of rutile TiO 2 (110) is studied using non-contact atomic force microscopy (NC-AFM) under ultra-high vacuum conditions. At first glance, the surface structure of antimony-doped TiO 2 (110) resembles the structure of pristine TiO 2 (110). However, in contrast to what is found in pristine TiO 2 (110), a dense layer of protruding features is observed upon antimony doping, which is tentatively ascribed to antimony-rich clusters. Moreover, homogeneously distributed holes are found on the surface, which differ in depth and shape depending on the preparation conditions. Holes with depths ranging from a few up to more than a hundred monatomic steps are observed. These holes are explained by surface segregation of antimony during annealing, as the ionic radius of Sb 3+ is considerably larger than the ionic radius of Ti 4+ . Our finding provides an indication of why an antimony concentration larger than the optimum ratio results in decreased photocatalytic activity. Moreover, controlling annealing temperature seems to constitute a promising strategy for creating nanosized holes on TiO 2 surfaces.

Photo catalytic degradation of nitrobenzene using nanocrystalline TiO2 photo catalyst doped with Zn ions

International Nuclear Information System (INIS)

Reynoso S, E. A.; Perez S, S.; Reyes C, A. P.; Castro R, C. L.; Felix N, R. M.; Lin H, S. W.; Paraguay D, F.; Alonso N, G.

2013-01-01

Photo catalysis is a method widely used in the degradation of organic pollutants of the environment. The development of new materials is very important to improve the photo catalytic properties and to find new applications for TiO 2 as a photo catalyst. In this article we reported the synthesis of a photo catalyst based on TiO 2 doped with Zn 2+ ions highly efficient in the degradation of nitrobenzene. The results of photo catalytic activity experiments showed that the Zn 2+ doped TiO 2 is more active that un-doped TiO 2 catalyst with an efficiency of 99% for the nitrobenzene degradation at 120 min with an apparent rate constant of 35 x 10 -3 min -1 . For the characterization of photo catalyst X-ray diffraction, transmission electron microscopy and Raman spectroscopy were used. (Author)

Simple method of preparing nitrogen - doped nanosized TiO2 powders of high photocatalytic activity under visible light

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Nguyen Van Hung; Dang Thi Thanh Le

2014-01-01

Nitrogen-doped nanosized TiO 2 powders were prepared by a simple thermal treatment method of the mixture of titanium dioxide and urea. The prepared products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectra (UV-Vis-DRS) and Fourier transform infrared (FT-IR) spectroscopy. The results showed that the crystal structure of N-TiO 2 was a mixture of anatase and rutile phases, and the average particle size was 31 nm calculated from XRD results. The UV-vis spectra indicate an increase in absorption of visible light when compared to undoped TiO 2 . The photocatalytic activity of nitrogen-doped TiO 2 powder was evaluated by the decomposition of methylene blue under visible light irradiation. And it was found that nitrogen-doped TiO 2 powders exhibited much higher photocatalytic activity than undoped TiO 2 . Moreover, the study also showed that, the doping N atoms improve the growth of the TiO 2 crystal and phase transformation. (author)

Preparation of anatase TiO2 thin films by vacuum arc plasma evaporation

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Miyata, Toshihiro; Tsukada, Satoshi; Minami, Tadatsugu

2006-01-01

Anatase titanium dioxide (TiO 2 ) 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 TiO 2 pellets as the source material. Highly transparent TiO 2 thin films prepared at substrate temperatures from room temperature to 400 deg. C exhibited photocatalytic activity, regardless whether oxygen (O 2 ) gas was introduced during the VAPE deposition. The highest photocatalytic activity and photo-induced hydrophilicity were obtained in anatase TiO 2 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 TiO 2 thin film with a resistivity of 2.6 x 10 -1 Ω cm was prepared at a substrate temperature of 400 deg. C without the introduction of O 2 gas

Comparative assessment of the efficiency of Fe-doped TiO2 prepared by two doping methods and photocatalytic degradation of phenol in domestic water suspensions

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Mst. Shamsun Nahar, Kiyoshi Hasegawa, Shigehiro Kagaya and Shigeyasu Kuroda

2007-01-01

Full Text Available Fe-doped TiO2 particles responding to visible light were synthesized by impregnation and calcination method using TiO2 particle and Ti element, respectively. The optical and the chemical properties were characterized by measuring the X-ray diffraction (XRD and UV–visible spectroscopy. The onset of absorption shifted to longer wavelengths on doping TiO2 by the calcination process, which showed a better response as compared to the impregnation method. The photocatalytic reactivity was evaluated by the degradation of phenol with impregnated Fe-doped (0.5% w/w in Fe and calcined Fe-doped (FexTi1−xO2, x=0.005 (Fe/Ti molar ratio TiO2 separately in distilled and tap water. The characterization results have confirmed the advanced possibility of correlation between photoactivity and the special property of sulfur-containing calcined Fe-doped TiO2. In case of the coagulation of the undoped A-I and the Fe-doped B-I, the photoactivity showed a decrease due to the presence of natural electrolytes and due to the high pH of tap water, whereas in the case of the coagulation of calcined Fe-doped TiO2 prepared from sulfides (FexTiS2, the photoactivity showed an increase. In this study, highest catalytic activity was found to be strongly dependent both on catalyst structure and on the type of water used.

Titanium dioxide-coated fluorine-doped tin oxide thin films for improving overall photoelectric property

International Nuclear Information System (INIS)

Li, Bao-jia; Huang, Li-jing; Ren, Nai-fei; Zhou, Ming

2014-01-01

Titanium (Ti) layers were deposited by direct current (DC) magnetron sputtering on commercial fluorine-doped tin oxide (FTO) glasses, followed by simultaneous oxidation and annealing treatment in a tubular furnace to prepare titanium dioxide (TiO 2 )/FTO bilayer films. Large and densely arranged grains were observed on all TiO 2 /FTO bilayer films. The presence of TiO 2 tetragonal rutile phase in the TiO 2 /FTO bilayer films was confirmed by X-ray diffraction (XRD) analysis. The results of parameter optimization indicated that the TiO 2 /FTO bilayer film, which was formed by adopting a temperature of 400 °C and an oxygen flow rate of 15 sccm, had the optimal overall photoelectric property with a figure of merit of 2.30 × 10 −2 Ω −1 , higher than 1.78 × 10 −2 Ω −1 for the FTO single-layer film. After coating a 500 nm-thick AZO layer by DC magnetron sputtering on this TiO 2 /FTO bilayer film, the figure of merit of the trilayer film achieved to a higher figure of merit of 3.12 × 10 −2 Ω −1 , indicating further improvement of the overall photoelectric property. This work may provide a scientific basis and reference for improving overall photoelectric property of transparent conducting oxide (TCO) films.

Structural, Optical, Morphological and Elemental Analysis on Sol-gel Synthesis of Ni Doped TiO2 Nanocrystallites

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T. Sakthivel

2017-06-01

Full Text Available Pure and Ni doped titanium dioxide nanoparticles were successfully synthesized by sol-gel method and characterized usingXRD, UV-Visible, FTIR, FESEM and EDS techniques. XRD pattern confirms the formation of tetragonal TiO2. The absorbance spectra of pure and Ni doped TiO2 showed absorption spectrum at ultra-violet region due to electronic transition between bonding and anti-bonding orbital (π-π•. Bandgap energy of Ni doped TiO2 decreased to 2.5 eV when compared to pure TiO2 (3.39 eV. FESEM study reveals agglomerated spherical shaped morphology. The functional groups of the prepared samples were identified using FTIR spectroscopy and the elemental analysis was further supported with EDS analysis.

Visible Light Irradiation-Mediated Drug Elution Activity of Nitrogen-Doped TiO2 Nano tubes

International Nuclear Information System (INIS)

Oh, S.; Moon, K.S.; Bae, J.M.; Moon, J.H.; Jin, S.

2013-01-01

We have developed nitrogen-doped TiO 2 nano tubes showing photo catalytic activity in the visible light region and have investigated the triggered release of antibiotics from these nano tubes in response to remote visible light irradiation. Scanning electron microscopy (SEM) observations indicated that the structure of TiO 2 nano tubes was not destroyed on the conditions of 0.05 and 0.1 M diethanolamine treatment. The results of X-ray photoelectron spectroscopy (XPS) confirmed that nitrogen, in the forms of nitrite (TiO 2 ) and nitrogen monoxide (NO), had been incorporated into the TiO 2 nano tube surface. A drug-release test revealed that the antibiotic-loaded TiO 2 nano tubes showed sustained and prolonged drug elution with the help of polylactic acid. Visible light irradiation tests showed that the antibiotic release from nitrogen-doped nano tubes was significantly higher than that from pure TiO 2 nano tubes (ρ ≨ 0.05).

Fe-N co-doped SiO2@TiO2 yolk-shell hollow nanospheres with enhanced visible light photocatalytic degradation

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Wan, Hengcheng; Yao, Weitang; Zhu, Wenkun; Tang, Yi; Ge, Huilin; Shi, Xiaozhong; Duan, Tao

2018-06-01

SiO2@TiO2 yolk@shell hollow nanospheres (STNSs) is considered as an outstanding photocatalyst due to its tunable structure and composition. Based on this point, we present an unprecedentedly excellent photocatalytic property of STNSs toward tannic acid via a Fe-N co-doped strategy. Their morphologies, compositions, structure and properties are characterized. The Fe-N co-doped STNSs formed good hollow yolk@shell structure. The results show that the energy gap of the composites can be downgraded to 2.82 eV (pure TiO2 = 3.2 eV). Photocatalytic degradation of tannic acid (TA, 30 mg L-1) under visible light (380 nm TiO2 nanospheres, non-doped STNSs and N-doped STNSs, the Fe-N co-doped STNSs exhibits the highest activity, which can degrade 99.5% TA into CO2 and H2O in 80 min. The probable degradation mechanism of the composites is simultaneously proposed, the band gap of STNSs becomes narrow by co-doping Fe-N, so that the TiO2 shell can stimulate electrons under visible light exposure, generate the ions of radOH and radO2- with a strong oxidizing property. Therefore this approach works is much desired for radioactive organic wastewater photocatalytic degradation.

Comparing Cr, and N only doping with (Cr,N)-codoping for enhancing visible light reactivity of TiO2

International Nuclear Information System (INIS)

Li, Yuan; Wang, Wei; Qiu, Xiaofeng; Meyer, Harry M. III; Paranthaman, Mariappan Parans; Eres, Gyula; Zhang, Zhenyu; Gu, Baohua

2011-01-01

The photoreactivity of titania (TiO2) nanoclusters with varying levels of N or Cr-doping, or (Cr,N)-codoping, was systematically investigated using photodegradation of methyl orange in aqueous suspensions. The shifting of the TiO2 absorption edge into the visible spectral region that is primarily attributable to band gap narrowing was found to be a reliable metric for estimating the photoreactivity of the doped nanoclusters. Compared to the weak response with undoped and N-doped TiO2, Cr-doping and (Cr, N)-codoping were found to significantly enhance photodegradation of methyl orange under visible light. The initial reaction rates increase from about 0 to above 1.6 10-2 min-1 when the doping concentration of Cr in TiO2 increases from 0 to 5%. In stark contrast, under UV irradiation, doping is not only ineffective but detrimental to the photoreactivity, and all doping including N or Cr only and (Cr, N)-codoping were found to reduce photoreactivity.

Highly Efficient Low-Temperature N-Doped TiO2 Catalysts for Visible Light Photocatalytic Applications

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Mahy, Julien G.; Cerfontaine, Vincent; Devred, François; Gaigneaux, Eric M.; Heinrichs, Benoît; Lambert, Stéphanie D.

2018-01-01

In this paper, TiO2 prepared with an aqueous sol-gel synthesis by peptization process is doped with nitrogen precursor to extend its activity towards the visible region. Three N-precursors are used: urea, ethylenediamine and triethylamine. Different molar N/Ti ratios are tested and the synthesis is adapted for each dopant. For urea- and trimethylamine-doped samples, anatase-brookite TiO2 nanoparticles of 6–8 nm are formed, with a specific surface area between 200 and 275 m2·g−1. In ethylenediamine-doped samples, the formation of rutile phase is observed, and TiO2 nanoparticles of 6–8 nm with a specific surface area between 185 and 240 m2·g−1 are obtained. X-ray photoelectron spectroscopy (XPS) and diffuse reflectance measurements show the incorporation of nitrogen in TiO2 materials through Ti–O–N bonds allowing light absorption in the visible region. Photocatalytic tests on the remediation of water polluted with p-nitrophenol show a marked improvement for all doped catalysts under visible light. The optimum doping, taking into account cost, activity and ease of synthesis, is up-scaled to a volume of 5 L and compared to commercial Degussa P25 material. This up-scaled sample shows similar properties compared to the lab-scale sample, i.e., a photoactivity 4 times higher than commercial P25. PMID:29642626

Evolution of structural and magnetic properties of Co-doped TiO2 thin films irradiated with 100 MeV Ag7+ ions

International Nuclear Information System (INIS)

Mohanty, P; Singh, V P; Rath, Chandana; Mishra, N C; Ojha, S; Kanjilal, D

2014-01-01

In continuation to our earlier studies where we have shown room temperature ferromagnetism observed in TiO 2 and Co-doped TiO 2 (CTO) thin films independent of their phase (Mohanty et al 2012 J. Phys. D: Appl. Phys. 45 325301), here the modifications in structure and magnetic properties in CTO thin films using 100 MeV Ag 7+ ion irradiation are reported. Owing to the important role of defects in tailoring the magnetic properties of the material, we vary the ion fluence from 5 × 10 11 to 1 × 10 12  ions cm −2 to create post-deposition defects. While the film deposited under 0.1 mTorr oxygen partial pressure retains its crystallinity showing radiation-resistant behaviour even at a fluence of 1 × 10 12  ions cm −2 , films deposited under 1 to 300 mTorr oxygen partial pressure becomes almost amorphous at the same fluence. Using Poisson's law, the diameter of the amorphized region surrounding the ion path is calculated to be ∼4.2 nm from the x-ray diffraction peak intensity ((1 1 0) for rutile phase) as a function of ion fluence. The saturation magnetization (M s ) decreases exponentially similar to the decrease in x-ray peak intensity with fluence, indicating magnetic disordered region surrounding the ion path. The diameter of the magnetic disordered region is found to be ∼6.6 nm which is larger than the diameter of the amorphized latent track. Therefore, it is confirmed that swift heavy ion irradiation induces a more significant magnetic disorder than the structural disorder. (paper)

Low temperature fabrication of V-doped TiO2 nanoparticles, structure and photocatalytic studies

International Nuclear Information System (INIS)

Liu Baoshun; Wang Xuelai; Cai Guofa; Wen Liping; Song Yanbao; Zhao Xiujian

2009-01-01

V-doped TiO 2 nanoparticles were synthesized at low temperature and characterized by X-ray diffraction (XRD), Raman spectroscopy (RS), transmission electron microscopy (TEM), Brunauer-Emmet-Teller (BET), X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy, and photoluminescence (PL) spectroscopy, respectively. It is found the nanoparticle shape changed from needle, to short stick and then to cubic with the increase of doped V concentration, which was also accompanied by the improvement of crystallinity. The specific surface area (S BET ) decreased with increasing V content. It is confirmed that V ions can be doped in TiO 2 by substituting Ti 4+ ions, which suppressed the CB → VB and surface recombination of photoinduced electrons and holes, and a relation was found between the PL spectra and the UV photocatalytic activity. There was an optimum V content for the V-doped TiO 2 to present the best UV-light induced photoactivity, but they were visible-inactive. At last, the effect of the doping V as trapping centers on photocatalysis was investigated in detail, and used to explain the difference between the photocatalysis under the illumination of UV light and visible light.

Highly Al-doped TiO2 nanoparticles produced by Ball Mill Method: structural and electronic characterization

International Nuclear Information System (INIS)

Santos, Desireé M. de los; Navas, Javier; Sánchez-Coronilla, Antonio; Alcántara, Rodrigo; Fernández-Lorenzo, Concha; Martín-Calleja, Joaquín

2015-01-01

Highlights: • Highly Al-doped TiO 2 nanoparticles were synthesized using a Ball Mill Method. • Al doping delayed anatase to rutile phase transformation. • Al doping allow controlling the structural and electronic properties of nanoparticles. - Abstract: This study presents an easy method for synthesizing highly doped TiO 2 nanoparticles. The Ball Mill method was used to synthesize pure and Al-doped titanium dioxide, with an atomic percentage up to 15.7 at.% Al/(Al + Ti). The samples were annealed at 773 K, 973 K and 1173 K, and characterized using ICP-AES, XRD, Raman spectroscopy, FT-IR, TG, STEM, XPS, and UV–vis spectroscopy. The effect of doping and the calcination temperature on the structure and properties of the nanoparticles were studied. The results show high levels of internal doping due to the substitution of Ti 4+ ions by Al 3+ in the TiO 2 lattice. Furthermore, anatase to rutile transformation occurs at higher temperatures when the percentage of doping increases. Therefore, Al doping allows us to control the structural and electronic properties of the nanoparticle synthesized. So, it is possible to obtain nanoparticles with anatase as predominant phase in a higher range of temperature

Multiwalled carbon nanotubes decorated with nitrogen, palladium co-doped TiO2 (MWCNT/N, Pd co-doped TiO2) for visible light photocatalytic degradation of Eosin Yellow in water

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Kuvarega, Alex T.; Krause, Rui W. M.; Mamba, Bhekie B.

2012-03-01

Multiwalled carbon nanotube (MWCNT/N), Pd co-doped TiO2 nanocomposites were prepared by calcining the hydrolysis products of the reaction of titanium isopropoxide, Ti(OC3H7)4 containing multiwalled carbon nanotubes with aqueous ammonia. The prepared samples were characterised by Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis, diffuse reflectance UV-Vis spectrophotometry (DRUV-Vis), XRD, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). DRUV-Vis analysis confirmed the red shift in the absorption edge at lower MWCNT percentages. SEM and TEM images showed the complete coverage of the MWCNTs with clusters of anatase TiO2 at low MWCNT percentages. Higher MWCNT levels led to their aggregation and consequently poor coverage by N, Pd co-doped TiO2. The photocatalytic activities of the nanocomposites were monitored by photodegradation of Eosin Yellow under simulated solar and visible light irradiation (λ > 450 nm). Irradiation with simulated solar radiation gave higher dye-degradation rates compared to visible radiation. The optimum MWCNT weight percentage in the composites was found to be 0.5. High degradation-rate constants of 3.42 × 10-2 and 5.18 × 10-3 min-1 were realised for the 0.5% MWCNT/N, Pd co-doped TiO2 composite, using simulated solar light and visible light, respectively.

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

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Siti Hajar Othman

2014-01-01

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

Role of Zn doping in oxidative stress mediated cytotoxicity of TiO2 nanoparticles in human breast cancer MCF-7 cells

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Ahamed, Maqusood; Khan, M. A. Majeed; Akhtar, Mohd Javed; Alhadlaq, Hisham A.; Alshamsan, Aws

2016-07-01

We investigated the effect of Zn-doping on structural and optical properties as well as cellular response of TiO2 nanoparticles (NPs) in human breast cancer MCF-7 cells. A library of Zn-doped (1-10 at wt%) TiO2 NPs was prepared. Characterization data indicated that dopant Zn was incorporated into the lattice of host TiO2. The average particle size of TiO2 NPs was decreases (38 to 28 nm) while the band gap energy was increases (3.35 eV-3.85 eV) with increasing the amount of Zn-doping. Cellular data demonstrated that Zn-doped TiO2 NPs induced cytotoxicity (cell viability reduction, membrane damage and cell cycle arrest) and oxidative stress (reactive oxygen species generation & glutathione depletion) in MCF-7 cells and toxic intensity was increases with increasing the concentration of Zn-doping. Molecular data revealed that Zn-doped TiO2 NPs induced the down-regulation of super oxide dismutase gene while the up-regulation of heme oxygenase-1 gene in MCF-7 cells. Cytotoxicity induced by Zn-doped TiO2 NPs was efficiently prevented by N-acetyl-cysteine suggesting that oxidative stress might be the primarily cause of toxicity. In conclusion, our data indicated that Zn-doping decreases the particle size and increases the band gap energy as well the oxidative stress-mediated toxicity of TiO2 NPs in MCF-7 cells.

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

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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.

Single-Nanoparticle Photoelectrochemistry at a Nanoparticulate TiO2 -Filmed Ultramicroelectrode.

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Peng, Yue-Yi; Ma, Hui; Ma, Wei; Long, Yi-Tao; Tian, He

2018-03-26

An ultrasensitive photoelectrochemical method for achieving real-time detection of single nanoparticle collision events is presented. Using a micrometer-thick nanoparticulate TiO 2 -filmed Au ultra-microelectrode (TiO 2 @Au UME), a sub-millisecond photocurrent transient was observed for an individual N719-tagged TiO 2 (N719@TiO 2 ) nanoparticle and is due to the instantaneous collision process. Owing to a trap-limited electron diffusion process as the rate-limiting step, a random three-dimensional diffusion model was developed to simulate electron transport dynamics in TiO 2 film. The combination of theoretical simulation and high-resolution photocurrent measurement allow electron-transfer information of a single N719@TiO 2 nanoparticle to be quantified at single-molecule accuracy and the electron diffusivity and the electron-collection efficiency of TiO 2 @Au UME to be estimated. This method provides a test for studies of photoinduced electron transfer at the single-nanoparticle level. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Annealing of TiO2 Films Deposited on Si by Irradiating Nitrogen Ion Beams

International Nuclear Information System (INIS)

Yokota, Katsuhiro; Yano, Yoshinori; Miyashita, Fumiyoshi

2006-01-01

Thin TiO2 films were deposited on Si at a temperature of 600 deg. C by an ion beam assisted deposition (IBAD) method. The TiO2 films were annealed for 30 min in Ar at temperatures below 700 deg. C. The as-deposited TiO2 films had high permittivities such 200 εo and consisted of crystallites that were not preferentially oriented to the c-axis but had an expanded c-axis. On the annealed TiO2 films, permittivities became lower with increasing annealing temperature, and crystallites were oriented preferentially to the (110) plane

Facile synthesis of the Ti3+ self-doped TiO2-graphene nanosheet composites with enhanced photocatalysis.

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Qiu, Bocheng; Zhou, Yi; Ma, Yunfei; Yang, Xiaolong; Sheng, Weiqin; Xing, Mingyang; Zhang, Jinlong

2015-02-26

This study developed a facile approach for preparing Ti(3+) self-doped TiO2-graphene photocatalyst by a one-step vacuum activation technology involved a relative lower temperature, which could be activated by the visible light owing to the synergistic effect among Ti(3+) doping, some new intersurface bonds generation and graphene oxide reduction. Compared with the traditional methods, the vacuum activation involves a low temperature and low-costing, which can achieve the reduction of GO, the self doping of Ti(3+) in TiO2 and the loading of TiO2 nanoparticles on GR surface at the same time. These resulting TiO2-graphene composites show the high photodegradation rate of MO, high hydrogen evolution activity and excellent IPCE in the visible light irradiation. The facile vacuum activation method can provide an effective and practical approach to improve the performance of TiO2-graphene and other metal oxides-graphene towards their practical photocatalytic applications.

Visible-Light-Active Titania Photocatalysts: The Case of N-Doped TiO2s—Properties and Some Fundamental Issues

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Alexei V. Emeline

2008-01-01

Full Text Available This article briefly reviews some factors that have impacted heterogeneous photocatalysis with next generation TiO2 photocatalysts, along with some issues of current debate in the fundamental understanding of the science that underpins the field. Preparative methods and some characteristics features of N-doped TiO2 are presented and described briefly. At variance are experimental results and interpretations of X-ray photoelectron spectra (XPS with regard to assignments of N 1s binding energies in N-doped TiO2 systems. Relative to pristine nominally clean TiO2 with absorption edges at 3.2 eV (anatase and 3.0 eV (rutile, N-doped TiO2s display red-shifted absorption edges into the visible spectral region. Several workers have surmised that the (intrinsic band gap of TiO2 is narrowed by coupling dopant energy states with valence band (VB states, an inference based on DFT computations. With similar DFT computations, others concluded that red-shifted absorption edges originate from the presence of localized intragap dopant states above the upper level of the VB band. Recent analyses of absorption spectral features in the visible region for a large number of doped TiO2 specimens, however, have suggested a common origin owing to the strong similarities of the absorption features, and this regardless of the preparative methods and the nature of the dopants. The next generation of (doped TiO2 photocatalysts should enhance overall process photoefficiencies (in some cases, since doped TiO2s absorb a greater quantity of solar radiation. The fundamental science that underpins heterogeneous photocatalysis with the next generation of photocatalysts is a rich playing field ripe for further exploration.

Fabrication of highly conductive Ta-doped SnO2 polycrystalline films on glass using seed-layer technique by pulse laser deposition

International Nuclear Information System (INIS)

Nakao, Shoichiro; Yamada, Naoomi; Hitosugi, Taro; Hirose, Yasushi; Shimada, Toshihiro; Hasegawa, Tetsuya

2010-01-01

We discuss the fabrication of highly conductive Ta-doped SnO 2 (Sn 1-x Ta x O 2 ; TTO) thin films on glass by pulse laser deposition. On the basis of the comparison of X-ray diffraction patterns and resistivity (ρ) values between epitaxial films and polycrystalline films deposited on bare glass, we proposed the use of seed-layers for improving the conductivity of the TTO polycrystalline films. We investigated the use of rutile TiO 2 and NbO 2 as seed-layers; these are isostructural materials of SnO 2, which are expected to promote epitaxial-like growth of the TTO films. The films prepared on the 10-nm-thick seed-layers exhibited preferential growth of the TTO (110) plane. The TTO film with x = 0.05 on rutile TiO 2 exhibited ρ = 3.5 x 10 -4 Ω cm, which is similar to those of the epitaxial films grown on Al 2 O 3 (0001).

Modeling and calculation of RKKY exchange coupling to explain Ti-vacancy-induced ferromagnetism in Ta-doped TiO2

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Majidi, Muhammad Aziz; Bupu, Annamaria; Fauzi, Angga Dito

2017-12-01

We present a theoretical study on Ti-vacancy-induced ferromagnetism in anatase TiO2. A recent experimental study has revealed room temperature ferromagnetism in Ta-doped anatase TiO2thin films (Rusydi et al., 2012) [7]. Ta doping assists the formation of Ti vacancies which then induce the formation of localized magnetic moments around the Ti vacancies. As neighboring Ti vacancies are a few unit cells apart, the ferromagnetic order is suspected to be mediated by itinerant electrons. We propose that such an electron-mediated ferromagnetism is driven by Ruderman-Kittel-Kasuya-Yosida (RKKY) exchange interaction. To examine our hypothesis, we construct a tight-binding based model Hamiltonian for the anatase TiO2 system. We calculate the RKKY exchange coupling constant of TiO2 as a function of distance between local magnetic moments at various temperatures. We model the system by taking only the layer containing a unit of TiO2, at which the Ti vacancy is believed to form, as our effective two-dimensional unit cell. Our model incorporates the Hubbard repulsive interactions between electrons occupying Ti d orbitals treated within mean-field approximation. The density of states profile resulting from the model captures the relevant electronic properties of TiO2, such as the energy gap of 3.4 eV and the n-type character, which may be a measure of the adequacy of the model. The calculated RKKY coupling constant shows that the ferromagnetic coupling extends up to 3-4 unit cells and enhances slightly as temperature is increased from 0 to 400 K. These results support our hypothesis that the ferromagnetism of this system is driven by RKKY mechanism.

Amorphous TiO2 doped with carbon for visible light photodegradation of rhodamine B and 4-chlorophenol

International Nuclear Information System (INIS)

Shao, Penghui; Tian, Jiayu; Zhao, Zhiwei; Shi, Wenxin; Gao, Shanshan; Cui, Fuyi

2015-01-01

Graphical abstract: - Highlights: • Amorphous TiO 2 doped with carbon is prepared as a visible photocatalyst. • RhB and 4-chlorophenol are decomposed effectively by carbon-doped amorphous TiO 2 . • The mechanism for visible light photocatalysis is discussed detailedly. - Abstract: Visible light photocatalytic activity of amorphous TiO 2 doped with carbon is prepared by a facile sol-gel route for the first time. The most active sample with mesostructure of amorphous phase, high surface area (273 m 2 g −1 ) and large pore volume (0.33 cm 3 g −1 ) is identified by X-ray diffractometer, Raman spectrometer, transmission electron microscope and N 2 adsorption–desorption isotherms. In addition, the most active sample is characterized by Fourier transform-infrared spectrometer, X-ray photoelectron spectrometer, UV–vis diffuse reflectance spectrometer and luminescence spectrometer. The results show that the most active sample with oxygenic groups has a narrower bandgap and lower recombination of electron–hole, due to the carbon doping and phase of amorphous. Effective photodegradation capability and stability of rhodamine B and colorless 4-chlorophenol are verified by photocatalytic tests under visible light irradiation. A possible mechanism of amorphous TiO 2 doped with carbon for visible light photocatalysis is proposed. The findings of this paper will provide new insights to design visible light-induced photocatalyst based on amorphous TiO 2 for organic removal

Multi-Layered TiO2 Films towards Enhancement of Escherichia coli Inactivation

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Sorachon Yoriya

2016-09-01

Full Text Available Crystalline TiO2 has shown its great photocatalytic properties in bacterial inactivation. This work presents a design fabrication of low-cost, layered TiO2 films assembled reactors and a study of their performance for a better understanding to elucidate the photocatalytic effect on inactivation of E. coli in water. The ability to reduce the number of bacteria in water samples for the layered TiO2 composing reactors has been investigated as a function of time, while varying the parameters of light sources, initial concentration of bacteria, and ratios of TiO2 film area and volume of water. Herein, the layered TiO2 films have been fabricated on the glass plates by thermal spray coating prior to screen printing, allowing a good adhesion of the films. Surface topology and crystallographic phase of TiO2 for the screen-printed active layer have been characterized, resulting in the ratio of anatase:rutile being 80:20. Under exposure to sunlight and a given condition employed in this study, the optimized film area:water volume of 1:2.62 has shown a significant ability to reduce the E. coli cells in water samples. The ratio of surface area of photocatalytic active base to volume of water medium is believed to play a predominant role facilitating the cells inactivation. The kinetic rate of inactivation and its behavior are also described in terms of adsorption of reaction species at different contact times.

Electrospinning processed nanofibrous TiO2 membranes for photovoltaic applications

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Onozuka, Katsuhiro; Ding, Bin; Tsuge, Yosuke; Naka, Takayuki; Yamazaki, Michiyo; Sugi, Shinichiro; Ohno, Shingo; Yoshikawa, Masato; Shiratori, Seimei

2006-02-01

We have recently fabricated dye-sensitized solar cells (DSSCs) comprising nanofibrous TiO2 membranes as electrode materials. A thin TiO2 film was pre-deposited on fluorine doped tin oxide (FTO) coated conducting glass substrate by immersion in TiF4 aqueous solution to reduce the electron back-transfer from FTO to the electrolyte. The composite polyvinyl acetate (PVac)/titania nanofibrous membranes can be deposited on the pre-deposited thin TiO2 film coated FTO by electrospinning of a mixture of PVac and titanium isopropoxide in N,N-dimethylformamide (DMF). The nanofibrous TiO2 membranes were obtained by calcining the electrospun composite nanofibres of PVac/titania as the precursor. Spectral sensitization of the nanofibrous TiO2 membranes was carried out with a ruthenium (II) complex, cis-dithiocyanate-N,N'-bis(2,2'-bipyridyl-4,4'-dicarboxylic acid) ruthenium (II) dihydrate. The results indicated that the photocurrent and conversion efficiency of electrodes can be increased with the addition of the pre-deposited TiO2 film and the adhesion treatment using DMF. Additionally, the dye loading, photocurrent, and efficiency of the electrodes were gradually increased by increasing the average thickness of the nanofibrous TiO2 membranes. The efficiency of the fibrous TiO2 photoelectrode with the average membrane thickness of 3.9 µm has a maximum value of 4.14%.

Blue to Yellow Photoluminescence Emission and Photocatalytic Activity of Nitrogen Doping in TiO2 Powders

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Gabriela Byzynski

2015-01-01

Full Text Available The defects caused by doping are important for understanding the increased photocatalytic activities of TiO2:N in organic reactions and in the evaluation of OH radical production after doping. TiO2:N was therefore synthesized using a modified polymeric method and N doping was performed by calcination with urea. The resulting powders were characterized using field emission scanning electron microscopy, X-ray diffraction, diffuse reflectance spectroscopy, Raman spectroscopy, Fourier transformation infrared spectroscopy, and photoluminescence emission spectroscopy (PL. N doping did not alter the morphology of the nanoparticles, and the anatase phase predominated, with the retention of the rutile phase. The band gap values, superficial areas, and crystallite sizes of the powders decreased after doping. The PL results showed an additional energy level in the TiO2:N band gap structure as a result of TiO2 lattice defects caused by doping. At low N contents, the powders showed continuous emissions from the blue region to the yellow region and a high N content shifted the PL emissions to the red region. These results suggest that the use of these powders could increase the efficiencies of solar cells and water-splitting processes. The photocatalytic activity of the powders under UVC illumination was confirmed for different organic dye molecules. The OH radical production did not change extensively after doping, as shown by experiments with terephthalic acid, and higher photocatalytic efficiencies in Rhodamine-B degradation under UVC illumination were achieved using the doped samples.

The Synergistic Effect of Nitrogen Dopant and Calcination Temperature on the Visible-Light-Induced Photoactivity of N-Doped TiO2

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Yao-Tung Lin

2013-01-01

Full Text Available The synergistic effect of nitrogen content and calcinations temperature on the N-doped TiO2 catalysts prepared by sol-gel method was investigated. The phase and structure, chemical state, optical properties, and surface area/pore distribution of N-doped TiO2 were characterized using X-ray diffraction spectrometer, high-resolution transmission electron microscope, X-ray photoelectron spectroscopy, UV-vis diffusion reflectance spectroscopy, and Brunauer-Emmett-Teller specific surface area. Finding showed that the photocatalytic activity of N-doped TiO2 was greatly enhanced compared to pure TiO2 under visible irradiation. N dopants could retard the transformation from anatase to rutile phase. Namely, N-doping effect is attributed to the anatase phase stabilization. The results showed nitrogen atoms were incorporated into the interstitial positions of the TiO2 lattice. Ethylene was used to evaluate the photocatalytic activity of samples under visible-light illumination. The results suggested good anatase crystallization, smaller particle size, and larger surface are beneficial for photocatalytic activity of N-doped TiO2. The N-doped TiO2 catalyst prepared with ammonia to titanium isopropoxide molar ratio of 2.0 and calcinated at 400°C showed the best photocatalytic ability.

Optical Properties and Surface Morphology of Nano-composite PMMA: TiO2 Thin Films

International Nuclear Information System (INIS)

Lyly Nyl Ismail; Ahmad Fairoz Aziz; Habibah Zulkefle

2011-01-01

There are two nano-composite PMMA: TiO 2 solutions were prepared in this research. First solution is nano-composite PMMA commercially available TiO 2 nanopowder and the second solution is nano-composite PMMA with self-prepared TiO 2 powder. The self-prepared TiO 2 powder is obtained by preparing the TiO 2 sol-gel. Solvo thermal method were used to dry the TiO 2 sol-gel and obtained TiO 2 crystal. Ball millers were used to grind the TiO 2 crystal in order to obtained nano sized powder. Triton-X was used as surfactant to stabilizer the composite between PMMA: TiO 2 . Besides comparing the nano-composite solution, we also studied the effect of the thin films thickness on the optical properties and surface morphology of the thin films. The thin films were deposited by sol-gel spin coating method on glass substrates. The optical properties and surface characterization were measured with UV-VIS spectrometer equipment and atomic force microscopy (AFM). The result showed that nano-composite PMMA with self prepared TiO 2 give high optical transparency than nano-composite PMMA with commercially available TiO 2 nano powder. The results also indicate as the thickness is increased the optical transparency are decreased. Both AFM images showed that the agglomerations of TiO 2 particles are occurred on the thin films and the surface roughness is increased when the thickness is increased. High agglomeration particles exist in the AFM images for nano-composite PMMA: TiO 2 with TiO 2 nano powder compare to the other nano-composite solution. (author)

Microporous TiO2-WO3/TiO2 films with visible-light photocatalytic activity synthesized by micro arc oxidation and DC magnetron sputtering

International Nuclear Information System (INIS)

Wu, Kee-Rong; Hung, Chung-Hsuang; Yeh, Chung-Wei; Wu, Jiing-Kae

2012-01-01

Highlights: ► A simple MAO is used to prepare porous WO 3 /TiO 2 layer on Ti sheet as a visible-light enabled catalyst. ► The photocatalytic activity of the WO 3 /TiO 2 is enhanced by sputtering over an N,C-TiO 2 layer. ► This is ascribed to the synergetic effect of hybrid sample prepared by two-step method. - Abstract: This study reports the preparation of microporous TiO 2 -WO 3 /TiO 2 films with a high surface area using a two-step approach. A porous WO 3 /TiO 2 template was synthesized by oxidizing a titanium sheet using a micro arc oxidation (MAO) process. This sheet was subsequently overlaid with a visible light (Vis)-enabled TiO 2 (N,C-TiO 2 ) film, which was deposited by codoping nitrogen (N) and carbon (C) ions into a TiO 2 lattice using direct current magnetron sputtering. The resulting microporous TiO 2 -WO 3 /TiO 2 film with a 0.38-μm-thick N,C-TiO 2 top-layer exhibited high photocatalytic activity in methylene blue (MB) degradation among samples under ultraviolet (UV) and Vis irradiation. This is attributable to the synergetic effect of two-step preparation method, which provides a highly porous microstructure and the well-crystallized N,C-TiO 2 top-layer. This is because a higher surface area with high crystallinity favors the adsorption of more MB molecules and more photocatalytic active areas. Thus, the microporous TiO 2 -WO 3 /TiO 2 film has promising applications in the photocatalytic degradation of dye solution under UV and Vis irradiation. These results imply that the microporous WO 3 /TiO 2 can be used as a template of hybrid electrode because it enables rapid fabrication.

Multifunctionality in coating films including Nb-doped TiO2 and Cs x WO3: near infrared shielding and photocatalytic properties

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Asakura, Yusuke; Anada, Yuto; Hamanaka, Ryo; Sato, Tsugio; Katsumata, Ken-ichi; Wu, Xiaoyong; Yin, Shu

2018-06-01

Various types of coating films were obtained from hydrothermally synthesized Nb-doped TiO2 (NTO) and Cs x WO3 (CWO) nanoparticles. The coating films possessed multifunctionality including near infrared (NIR) absorption and photocatalysis abilities. The NTO and CWO nanoparticles were synthesized by a unique solvothermal reaction in which water induced by an esterification reaction between alcohol and carboxylic acid can act as a hydrolyzing agent for metal precursors. NTO was synthesized by the unique solvothermal reaction for the first time. The reaction accompanied by the reduction of Ti4+ to Ti3+ led to the formation of nanoparticles with both NIR absorption and photocatalytic properties. The effect of the ethanol–acetic acid ratio on the morphology of the obtained NTO was investigated, and the larger amount of acetic acid led to a larger nanoparticle size, indicating the size controllability. The two types of coating film, including CWO and NTO nanoparticles, were obtained for comparison: (1) coexistent coating film: one side of the quartz glass was coated with a dispersion, including both CWO and NTO nanoparticles, and (2) double-sided coating film: a quartz glass coated with a CWO dispersion on one side and an NTO dispersion on the other side. The double-sided coating led to higher multifunctionality. Furthermore, the optimized condition for the double-sided coating was investigated by using various NTO particles obtained using different ethanol–acetic acid ratios.

Photoluminescence studies on Eu doped TiO2 nanoparticles

International Nuclear Information System (INIS)

Ningthoujam, R.S.; Sudarsan, V.; Vatsa, R.K.; Kadam, R.M.; Jagannath; Gupta, A.

2009-01-01

Eu 3+ doped TiO 2 nanoparticles were prepared by urea hydrolysis in ethylene glycol medium at low temperature of 150 deg. C. X-ray diffraction study showed that anatase phase of tetragonal structure was formed below 500 deg. C; and above this temperature, additional peaks due to rutile phase were also observed. From luminescence study, it was found that as prepared nanoparticles showed the enhanced luminescence intensity due to energy transfer from host to europium ions. However, photoluminescence from these nanoparticles was found to disappear when the samples were heated above 900 deg. C. We established the origin of the reduction in the luminescence intensity from Eu 3+ when doped in TiO 2 and heated at 900 deg. C. Based on detailed studies at different heat-treatment temperatures using techniques such as X-ray diffraction, X-ray photoelectron spectroscopy, electron paramagnetic resonance, Raman spectroscopy, and Moessbauer spectroscopy, it has been established that formation of Eu 2 Ti 2 O 7 phase, wherein Eu 3+ ions occupy high symmetric environment (D 3d ) and also reduced distance between Eu 3+ and Eu 3+ ions is responsible for the decrease/loss in the luminescence intensity.

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

International Nuclear Information System (INIS)

Naseri, N; Amiri, M; Moshfegh, A Z

2010-01-01

In this investigation, the effect of annealing temperature and concentration of gold nanoparticles on the photoelectrochemical properties of sol-gel deposited Au : TiO 2 nanocomposite thin films is studied. Various gold concentrations have been added to the TiO 2 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 : TiO 2 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 TiO 2 nanocrystalline thin films. X-ray photoelectron spectroscopy reveals that the presence of gold in the metallic state and the formation of TiO 2 are stoichiometric. The photoelectrochemical properties of the Au : TiO 2 samples are characterized using a compartment cell containing H 2 SO 4 and KOH as cathodic and anodic electrolytes, respectively. It is found that the addition of Au nanoparticles in TiO 2 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.

Effects of photocatalytic activity of metal and non-metal doped Tio2 for Hydrogen production enhancement - A Review

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Nur Aqilah Sulaiman, Siti; Zaky Noh, Mohamad; Nadia Adnan, Nurul; Bidin, Noriah; Razak, Siti Noraiza Ab

2018-05-01

Titanium dioxide TiO2 is well-known materials that has become an efficient photocatalyst for environmental sustainability. Known as solar driven catalysis, TiO2 is considered as the most promising way to alleviate environmental issues caused by the combustion of fossil fuels and to meet worldwide demands for energy. Much effort has been concerned on TiO2 band gap modification to become a visible-light-activated photocatalysts of TiO2 because it can only be excited by UV light irradiation due to its large band gap. Modifications like metals and nonmetals doping has been proposed in the past decades. This reviews survey recent advanced preparation methods of doped-TiO2 including various types of doping methods for various types of dopants and provides general review on further modifications. The characterizations techniques used in order to determine the structural, morphological and optical properties of modified TiO2 is also discussed. Further, a new method of TiO2 modification is proposed in this mini review paper.

Characterization and photocatalytic performance evaluation of various metal ion-doped microstructured TiO2 under UV and visible light.

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Sahoo, Chittaranjan; Gupta, Ashok K

2015-01-01

Commercially available microcrystalline TiO2 was doped with silver, ferrous and ferric ion (1.0 mol %) using silver nitrate, ferrous sulfate and ferric nitrate solutions following the liquid impregnation technology. The catalysts prepared were characterised by FESEM, XRD, FTIR, DRS, particle size and micropore analysis. The photocatalytic activity of the prepared catalysts was tested on the degradation of two model dyes, methylene blue (3,7-bis (Dimethylamino)-phenothiazin-5-ium chloride, a cationic thiazine dye) and methyl blue (disodium;4-[4-[[4-(4-sulfonatoanilino)phenyl]-[4-(4-sulfonatophenyl)azaniumylidenecyclohexa-2,5-dien-1-ylidene]methyl]anilino]benzene sulfonate, an anionic triphenyl methane dye) under irradiation by UV and visible light in a batch reactor. The efficiency of the photocatalysts under UV and visible light was compared to ascertain the light range for effective utilization. The catalysts were found to have the anatase crystalline structure and their particle size is in a range of 140-250 nm. In the case of Fe(2+) doped TiO2 and Fe(3+) doped TiO2, there was a greater shift in the optical absorption towards the visible range. Under UV light, Ag(+) doped TiO2 was the most efficient catalyst and the corresponding decolorization was more than 99% for both the dyes. Under visible light, Fe(3+) doped TiO2 was the most efficient photocatalyst with more than 96% and 90% decolorization for methylene blue and methyl blue, respectively. The kinetics of the reaction under both UV and visible light was investigated using the Langmuir-Hinshelwood pseudo-first-order kinetic model. Kinetic measurements confirmed that, Ag(+) doped TiO2 was most efficient in the UV range, while Fe(3+) doped TiO2 was most efficient in the visible range.

The TiO2 Refraction Film for CsI Scintillator

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