Structural phase analysis and photoluminescence properties of Mg-doped TiO2 nanoparticles

Science.gov (United States)

Ali, T.; Ashraf, M. Anas; Ali, S. Asad; Ahmed, Ateeq; Tripathi, P.

2018-05-01

In this paper, we report the synthesis, characterization and photoluminescence properties of Mg-doped TiO2 nanoparticles (NPs). The samples were synthesized by sol-gel method and characterized using the standard analytical techniques such as X-ray diffraction (XRD), Transmission electron microscope (TEM), Energy dispersive X-ray spectroscopy (EDX), UV-visible and photoluminescence spectroscopy. The powder XRD spectra revealed that the synthesized samples are pure and crystalline in nature and showing tetragonal anatase phase of TiO2 NPs. UV-visible spectrum illustrates that an absorption edge shifts toward the visible region. This study may provide a new insight for making the nanomaterials which can be used in photocatalytic applications.

Surface plasmon resonance effect of Cu nanoparticles in a dye sensitized solar cell

International Nuclear Information System (INIS)

Dhonde, Mahesh; Sahu, Kirti; Murty, V.V.S.; Nemala, Siva Sankar; Bhargava, Parag

2017-01-01

Highlights: •Pure and Cu-doped TiO 2 Nanoparticles are synthesized and incorporated in DSSCs. •Addition of Cu provided high surface area and reduced charge recombination due to LSPR effect. •The highest photo conversion efficiency achieved is 8.65% with J sc of 18.8 mA cm −2 . •This efficiency is 26% higher than that of pure TiO 2 DSSC. -- Abstract: Pure and copper doped titanium dioxide nanoparticles (TiO 2 NPs) for Dye Sensitized Solar Cell (DSSC) photo anodes with different doping amounts of copper (Cu) 0.1, 0.3 and 0.5 mole% are synthesized using modified sol-gel route. Addition of Cu in TiO 2 matrix can enhance absorption towards visible spectrum and can reduce the charge carrier recombination due to Localized Surface Plasmon Resonance (LSPR). The samples are characterized by X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), UV–vis spectroscopy (UV-VIS), X-ray Photoelectron Spectroscopy (XPS), Electro Chemical Impedance Spectroscopy (EIS). The crystallite size is measured by XRD and surface morphology of the samples is analyzed using SEM. UV–vis measurement shows that the influence of Cu in TiO 2 lattice altered its optical properties and extended absorption in the visible region. The resistances between different junctions of the cell are measured by EIS. The J-V measurement of the cell prepared using pure and Cu-doped TiO 2 NPs is carried out by solar simulator. The optimized Cu doped DSSC with 0.3 mole% Cu in TiO 2 shows the best power conversion efficiency of 8.65% which is approximately 26% greater than the efficiency of undoped DSSC (6.41%).

Thermal analysis and temperature dependent dielectric responses of Co doped anatase TiO2 nanoparticles

International Nuclear Information System (INIS)

Alamgir; Khan, Wasi; Ahammed, Nashiruddin; Naqvi, A. H.; Ahmad, Shabbir

2015-01-01

Nanoparticles (NPs) of pure and 5 mol % cobalt doped TiO 2 synthesized through acid modified sol-gel method were characterized to understand their thermal, structural, morphological, and temperature dependent dielectric properties. Thermogravimetric analysis (TGA) has been used for thermal studies and indicates the weight loss in two steps due to the removal of residual organics. X-ray diffraction study was employed to confirm the formation of single anatase phase with tetragonal symmetry for both pure and 5 mol % Co doped TiO 2 NPs. The average crystallite size of both samples was calculated from the Scherrer’s formula and was found in the range from 9-11 nm. TEM micrographs of these NPs reflect their shape and distribution. The dielectric constant (ε′), dielectric loss (tanδ) and ac conductivity (σ ac ) were also studied as a function of temperature at different frequencies. Electrical responses of the synthesized NPs have been analyzed carefully in the framework of relevant models. It is also noticed that the dielectric constant (ε′) of the samples found to decrease with increasing frequency but increases with increasing temperature up to a particular value and then sharply decreases. Temperature variation of dielectric constant exhibits step like escalation and shows relaxation behavior. Study of dielectric properties shows dominant dependence on the grain size as well as Co ion incorporation in TiO 2

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.

Conductometric sensor for ammonia and ethanol using gold nanoparticle-doped mesoporous TiO2

International Nuclear Information System (INIS)

Xiong, Wei; Liu, Huanhuan; Liu, Shantang

2015-01-01

We describe uniform and high-temperature-stable mesoporous TiO 2 beads functionalized with gold nanoparticles (AuNPs-TiO 2 ) for use in conductometric sensing of gases and organic vapors. The size of the interconnected main mesopores of the TiO 2 beads ranges from 8 to 15 nm, and the AuNPs have diameters between 8 and 10 nm. The mesoporous TiO 2 beads are formed during calcination while the structure-directing template agent is removed. Monodispersed AuNPs are formed by reduction in-situ and are placed inside the mesoporous TiO 2 framework. This prevents aggregation of the AuNPs even at 500 °C. The materials were characterized by UV–vis spectroscopy, scanning and transmission electron microscopy, nitrogen adsorption-desorption, and X-ray diffraction. Comb-type gold electrodes were then fabricated on an alumina substrate and are shown to display excellent properties in terms of sensing ammonia, ethanol, methanol or acetone. The sensitivity (defined as the ratio of resistivities under vapor and air) of a typical AuNPs(0.5 %)-TiO 2 gas sensor for ethanol reached up to 5.65 at above 600 ppm at 75 °C. Response time and recovery times (t 90  ≤ 20 s) are faster than (or comparable to) other metal-doped TiO 2 sensors, and working temperatures are much lower. An interesting observation was made in that the changes in the conductivity of the sensor change with temperature. The sensor prepared with AuNPs(0.5 %)-TiO 2 is of the p-type (in its response to ammonia gas) at 45 °C, but becomes n-type at 20 °C. Obviously, rather slight changes in temperature lead to a complete change in the direction of the conductometric signal change. This may provide a new aspect in terms of selective and highly sensitive detection of ammonia at ambient and slightly elevated temperatures. (author)

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.

New vision to CuO, ZnO, and TiO2 nanoparticles: their outcome and effects

Science.gov (United States)

Chibber, Sandesh; Ansari, Shakeel Ahmed; Satar, Rukhsana

2013-04-01

Nanomaterials and nanotechnology have attracted more and more attention due to their wide ranges of applications in various fields. With a high level of surface energy, high magnetism, high surface area, and low melting point, engineered nanoparticles (ENPs) has been widely used in industry for various applications. Metal nanoparticles, in particular, have been shown to cause significant biological effects. Review discusses cytotoxic to neurotoxic effects of CuO, ZnO, and TiO2 nanoparticles based on the scenario drawn from various in vitro and in vivo studies. ENPs such as TiO2 and ZnO NPs have great practical importance in industrial applications. CuO NPs is also widely used in biomedical applications as catalyst supports, drug carriers, and gene delivery. However, study conducted on TiO2 NPs have forecast that oxidative DNA damage could be attributed due to reduced glutathione levels with concomitant increase in lipid peroxidation and reactive oxygen species generation. Moreover, there are many evidences showing that ZnO NP and CuO NPs generates ROS production and can cause cell death in different types of cultured cell. Nanoparticle toxicity is assessed by set of tests designed to characterize a given risk and also the mechanism for related outcomes. Conclusively, it becomes more and more important for nanotechnologist to understand the potential health effects of ENPs and what new methodology can be applied to reveal problems like gene silencing and inhibition in antioxidant defense mechanism which can be occurred on severe effects to oxidative stress by ENPs.

New vision to CuO, ZnO, and TiO2 nanoparticles: their outcome and effects

International Nuclear Information System (INIS)

Chibber, Sandesh; Ansari, Shakeel Ahmed; Satar, Rukhsana

2013-01-01

Nanomaterials and nanotechnology have attracted more and more attention due to their wide ranges of applications in various fields. With a high level of surface energy, high magnetism, high surface area, and low melting point, engineered nanoparticles (ENPs) has been widely used in industry for various applications. Metal nanoparticles, in particular, have been shown to cause significant biological effects. Review discusses cytotoxic to neurotoxic effects of CuO, ZnO, and TiO 2 nanoparticles based on the scenario drawn from various in vitro and in vivo studies. ENPs such as TiO 2 and ZnO NPs have great practical importance in industrial applications. CuO NPs is also widely used in biomedical applications as catalyst supports, drug carriers, and gene delivery. However, study conducted on TiO 2 NPs have forecast that oxidative DNA damage could be attributed due to reduced glutathione levels with concomitant increase in lipid peroxidation and reactive oxygen species generation. Moreover, there are many evidences showing that ZnO NP and CuO NPs generates ROS production and can cause cell death in different types of cultured cell. Nanoparticle toxicity is assessed by set of tests designed to characterize a given risk and also the mechanism for related outcomes. Conclusively, it becomes more and more important for nanotechnologist to understand the potential health effects of ENPs and what new methodology can be applied to reveal problems like gene silencing and inhibition in antioxidant defense mechanism which can be occurred on severe effects to oxidative stress by ENPs.

Fabrication of folic acid sensor based on the Cu doped SnO2 nanoparticles modified glassy carbon electrode

International Nuclear Information System (INIS)

Lavanya, N; Radhakrishnan, S; Sudhan, N; Sekar, C; Leonardi, S G; Neri, G; Cannilla, C

2014-01-01

A novel folic acid biosensor has been fabricated using Cu doped SnO 2 nanoparticles (NPs) synthesized by a simple microwave irradiation method. Powder XRD and TEM studies confirmed that both the pure and Cu doped SnO 2 (Cu: 0, 10, 20wt%) crystallized in tetragonal rutile-type structure with spherical morphology. The average crystallite size of pure SnO 2 was estimated to be around 16 nm. Upon doping, the crystallite sizes decreased to 9 nm and 5 nm for 10 and 20wt% Cu doped SnO 2 respectively. XPS studies confirmed the electronic state of Sn and Cu to be 4+ and 2+ respectively. Cu (20wt%) doped SnO 2 NPs are proved to be a good sensing element for the determination of folic acid (FA). Cu-SnO 2 NPs (20wt%) modified glassy carbon electrode (GCE) exhibited the lowest detection limit of 0.024 nM over a wide folic acid concentration range of 1.0 × 10 −10 to 6.7 × 10 −5 M at physiological pH of 7.0. The fabricated sensor is highly selective towards the determination of FA even in the presence of a 100 fold excess of common interferent ascorbic acid. The sensor proved to be useful for the estimation of FA content in pharmaceutical sample with satisfactory recovery. (paper)

Effect of titanium dioxide nanoparticles (TiO2 NPs) on the expression of mucin genes in human airway epithelial cells.

Science.gov (United States)

Kim, Gui Ok; Choi, Yoon Seok; Bae, Chang Hoon; Song, Si-Youn; Kim, Yong-Dae

2017-01-01

Titanium dioxide nanoparticles (TiO 2 NPs) are utilized with growing frequency for a wide variety of industrial applications. Recently, acute and chronic exposures to TiO 2 NPs have been found to induce inflammatory response in the human respiratory tract. However, the effect and mechanism underlying the induction of major airway mucins by TiO 2 NPs have not been elucidated. This study was conducted to characterize the effect of TiO 2 NPs, and the mechanism involved, on the expressions of airway mucins in human airway epithelial cells. In NCI-H292 cells and primary cultures of normal nasal epithelial cells, the effects of TiO 2 NPs and signaling pathway for airway mucin genes were investigated by reverse transcriptase-polymerase chain reaction (RT-PCR), real-time PCR, enzyme immunoassays and immunoblot analysis using several specific inhibitors and small interfering RNAs (siRNAs). TiO 2 NPs increased MUC5B expression and activated the phosphorylations of extracellular signal-related kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (MAPK). U0126 (an ERK1/2 MAPK inhibitor) and SB203580 (a p38 MAPK inhibitor) inhibited TiO 2 NPs-induced MUC5B expression. And knockdown of ERK1, ERK2 and p38 MAPK using siRNAs significantly blocked TiO 2 NPs-induced MUC5B mRNA expression. Furthermore, Toll-like receptor 4 (TLR4) mRNA expression was increased by TiO 2 NPs, and knockdown by TLR4 siRNA significantly attenuated TiO 2 NPs-induced MUC5B mRNA expression and the TiO 2 NPs-induced phosphorylations of ERK1/2 and p38 MAPK. These results demonstrate for the first time that TiO 2 NPs induce MUC5B expression via TLR4-dependent ERK1/2 and p38 MAPK signaling pathways in respiratory epithelium.

Nanoparticulate anatase TiO2 (TiO2 NPs) upregulates the expression of silkworm (Bombyx mori) neuropeptide receptor and promotes silkworm feeding, growth, and silking.

Science.gov (United States)

Ni, Min; Zhang, Hua; Li, Fan Chi; Wang, Bin Bin; Xu, Kai Zun; Shen, Wei De; Li, Bing

2015-06-01

Bombyx mori orphan G protein-coupled receptor, BNGR-A4, is the specific receptor of B. mori neuropeptide F (BmNPFR, neuropeptide F designated NPF). BmNPFR binds specifically and efficiently to B. mori neuropeptides BmNPF1a and BmNPF1b, which activates the ERK1/2 signaling pathway to regulate B. mori food intake and growth. Titanium dioxide nanoparticles (TiO2 NPs) can promote B. mori growth. However, whether the mechanisms of TiO2 NPs' effects are correlated with BmNPFR remains unknown. In this study, the effects of TiO2 NPs (5mg/L) feeding and BmNPFR-dsRNA injection on B. mori food intake and growth were investigated; after TiO2 NPs treatments, B. mori food intake, body weight, and cocoon shell weight were 5.82%, 4.64%, and 9.30% higher, respectively, than those of controls. The food intake, body weight, and cocoon shell weight of the BmNPFR-dsRNA injection group were reduced by 8.05%, 6.28%, and 6.98%, respectively, compared to the control. After TiO2 NPs treatment for 72h, the transcriptional levels of BmNPFR, BmNPF1a, and BmNPF1b in the midgut were 1.58, 1.43, and 1.34-folds, respectively, of those of the control, but 1.99, 2.26, and 2.19-folds, respectively, of the BmNPFR-dsRNA injection group; the phosphorylation level of MAPK was 24.03% higher than the control, while the phosphorylation level of BmNPFR-dsRNA injection group was 71.00% of control. The results indicated that TiO2 NPs affect B. mori feeding and growth through increasing the expression of BmNPFR. This study helps clarify the roles of BmNPF/BmNPFR system in TiO2 NPs' effects on B. mori feeding, growth, and development. Copyright © 2015 Elsevier Inc. All rights reserved.

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.

Photocatalytic properties and selective antimicrobial activity of TiO2(Eu)/CuO nanocomposite

International Nuclear Information System (INIS)

Michal, Robert; Dworniczek, Ewa; Caplovicova, Maria; Monfort, Olivier; Lianos, Panagiotis; Caplovic, Lubomir; Plesch, Gustav

2016-01-01

Highlights: • Nanocomposites composed of Eu-doped anatase grafted with CuO. • Increase in photocatalytic hydrogen production due to CuO acting as electrons sink. • CuO in composites decreasing the photoinduced total mineralization of phenol. • Selective photoinduced antimicrobial activity against Enterococcus species. - Abstract: TiO 2 (Eu)/CuO nanocomposites were prepared by precipitation method. The anatase nanocrystallites with a size of 26 nm exhibited well crystallized and characteristical dipyramidal morphology and {1 0 1} and {0 0 1} faceting. Transmission electron microscopy photographs with atomic resolution showed that the Eu(III) dopants were bounded on surface of titania. In the composites, the CuO nanocrystals exhibiting a monoclinic tenorite structure with a size in the range from 2 to 5 nm were grafted to the surface of titania. The influence of copper(II) oxide led to distinct selectivity in the photocatalytic and antimicrobial properties of the investigated TiO 2 (Eu)/CuO nanocomposites. While the presence of CuO nanocrystals strongly increased the photocatalytic production of hydrogen by ethanol reforming, it decreased the activity in photoinduced total mineralization of phenol comparing with non-modified TiO 2 (Eu). In investigated TiO 2 (Eu)/CuO powders, the photoinduced antimicrobial activity against membranes of Enterococcus species was influenced by the selective binding of CuO to the surface of the microorganism leading to distinct selectivity in their action. The activity against Enterococcus faecalis was higher than against Enterococcus faecium.

Role of dopant concentration, crystal phase and particle size on microbial inactivation of Cu-doped TiO{sub 2} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Sahu, Manoranjan; Wu Bing; Zhu Liying; Jacobson, Craig; Wang Weining; Jones, Kristen; Goyal, Yogesh; Tang, Yinjie J; Biswas, Pratim, E-mail: pbiswas@wustl.edu [Department of Energy, Environmental and Chemical Engineering, Washington University in St Louis, St Louis, MO 63130 (United States)

2011-10-14

The properties of Cu-doped TiO{sub 2} nanoparticles (NPs) were independently controlled in a flame aerosol reactor by varying the molar feed ratios of the precursors, and by optimizing temperature and time history in the flame. The effect of the physico-chemical properties (dopant concentration, crystal phase and particle size) of Cu-doped TiO{sub 2} nanoparticles on inactivation of Mycobacterium smegmatis (a model pathogenic bacterium) was investigated under three light conditions (complete dark, fluorescent light and UV light). The survival rate of M. smegmatis (in a minimal salt medium for 2 h) exposed to the NPs varied depending on the light irradiation conditions as well as the dopant concentrations. In dark conditions, pristine TiO{sub 2} showed insignificant microbial inactivation, but inactivation increased with increasing dopant concentration. Under fluorescent light illumination, no significant effect was observed for TiO{sub 2}. However, when TiO{sub 2} was doped with copper, inactivation increased with dopant concentration, reaching more than 90% (>3 wt% dopant). Enhanced microbial inactivation by TiO{sub 2} NPs was observed only under UV light. When TiO{sub 2} NPs were doped with copper, their inactivation potential was promoted and the UV-resistant cells were reduced by over 99%. In addition, the microbial inactivation potential of NPs was also crystal-phase-and size-dependent under all three light conditions. A lower ratio of anatase phase and smaller sizes of Cu-doped TiO{sub 2} NPs resulted in decreased bacterial survival. The increased inactivation potential of doped TiO{sub 2} NPs is possibly due to both enhanced photocatalytic reactions and leached copper ions.

Heterojunctions of mixed phase TiO2 nanotubes with Cu, CuPt, and Pt nanoparticles: interfacial band alignment and visible light photoelectrochemical activity

Science.gov (United States)

Kar, Piyush; Zhang, Yun; Mahdi, Najia; Thakur, Ujwal K.; Wiltshire, Benjamin D.; Kisslinger, Ryan; Shankar, Karthik

2018-01-01

Anodically formed, vertically oriented, self-organized cylindrical TiO2 nanotube arrays composed of the anatase phase undergo an interesting morphological and phase transition upon flame annealing to square-shaped nanotubes composed of both anatase and rutile phases. This is the first report on heterojunctions consisting of metal nanoparticles (NPs) deposited on square-shaped TiO2 nanotube arrays (STNAs) with mixed rutile and anatase phase content. A simple photochemical deposition process was used to form Cu, CuPt, and Pt NPs on the STNAs, and an enhancement in the visible light photoelectrochemical water splitting performance for the NP-decorated STNAs was observed over the bare STNAs. Under narrow band illumination by visible photons at 410 nm and 505 nm, Cu NP-decorated STNAs performed the best, producing photocurrents 80% higher and 50 times higher than bare STNAs, respectively. Probing the energy level structure at the NP-STNA interface using ultraviolet photoelectron spectroscopy revealed Schottky barrier formation in the NP-decorated STNAs, which assists in separating the photogenerated charge carriers, as also confirmed by longer charge carrier lifetimes in NP-decorated STNAs. While all the NP-decorated STNAs showed enhanced visible light absorption compared to the bare STNAs, only the Cu NPs exhibited a clear plasmonic behavior with an extinction cross section that peaked at 550 nm.

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

Effect of Cu2O morphology on photocatalytic hydrogen generation and chemical stability of TiO2/Cu2O composite.

Science.gov (United States)

Zhu, Lihong; Zhang, Junying; Chen, Ziyu; Liu, Kejia; Gao, Hong

2013-07-01

Improving photocatalytic activity and stability of TiO2/Cu2O composite is a challenge in generating hydrogen from water. In this paper, the TiO2 film/Cu2O microgrid composite was prepared via a microsphere lithography technique, which possesses a remarkable performance of producing H2 under UV-vis light irradiation, in comparison with pure TiO2 film, Cu2O film and TiO2 film/Cu2O film. More interesting is that in TiO2 film/Cu2O microgrid, photo-corrosion of Cu2O can be retarded. After deposition of Pt on its surface, the photocatalytic activity of TiO2/Cu2O microgrid in producing H2 is improved greatly.

Electrochemical Behavior of TiO2 Nanoparticle Doped WO3 Thin Films

Directory of Open Access Journals (Sweden)

Suvarna R. Bathe

2014-01-01

Full Text Available Nanoparticle TiO2 doped WO3 thin films by pulsed spray pyrolysis technique have been studied on fluorine tin doped (FTO and glass substrate. XRD shows amorphous nature for undoped and anatase phase of TiO2 having (101 plane for nanoparticle TiO2 doped WO3 thin film. SEM shows microfibrous reticulated porous network for WO3 with 600 nm fiber diameter and nanocrystalline having size 40 nm for TiO2 nanoparticle doped WO3 thin film. TiO2 nanoparticle doped WO3 thin film shows ~95% reversibility due to may be attributed to nanocrystalline nature of the film, which helpful for charge insertion and deinsertion process. The diffusion coefficient for TiO2 nanoparticle doped WO3 film is less than undoped WO3.

SU-G-TeP3-15: Radiation Dose Enhancement by Anatase TiO2NPs

Energy Technology Data Exchange (ETDEWEB)

Youkhana, E; Geso, M; Feltis, B [RMIT University, Melbourne, VIC (Australia)

2016-06-15

Purpose: This work investigates radiation dose enhancement caused by TiO2 nanoparticles covering entire X-ray energy ranges used in radiation therapy. Methods: Anatase TiO2NPs crystal were synthesised and modified as hydrophilic and hydrophobic to disperse in culture-medium and halocarbons (PRESAGE chemical composition) respectively. TiO2NPs were characterised using TEM, XPS, XRD, TGA and FTIR. Various Concentrations have been utilised for determination of radiation-dose enhancement. This investigation is carried out in two ways; one using PRESAGE dosimeter/phantom and the other is radiobiological and based on in vitro study using two types of cell lines, Human Keratinocyte (HaCaT) and prostate cancer cell lines. The x-ray used are both kilovoltage and megavoltage separately. The prepared PRESAGE dosimeters were scanned using optical CT scanner. Clonogenic and MTS assays were employed for cell cytotoxicity and viability measurements for determination of the levels of dose enhancement. Results: Significant about (50%, 45%) dose enhancement by TiO2-NPs for kV x-rays is measured in both ways (Presage and Cells study). Slightly more is detected with the cells. However, the dose enhancement with megavoltage beams was insignificant using Presage and under same conditions the cells survival curves indicates around 20% which is relatively high. This difference can only be attributed to some biochemical effects. Such as generation of reactive oxygen species (ROS), this can affect the cells while it can’t be detected by Presage. Elevation of hydroxyl radicals (•OH) of many orders is observed with the inclusion of TiO2-NPs in cells-medium. Conclusion: Dose enhancement inflicted by TiO2-NPs is proven to be significant with megavoltage beams and minimal with kV. The high dose enhancements obtained can be attributed to higher levels of ROS generated. Since MV beams are most commonly used, this research proves potential value for more efficient beam delivery. This has

Proteomic response of mussels Mytilus galloprovincialis exposed to CuO NPs and Cu{sup 2+}: An exploratory biomarker discovery

Energy Technology Data Exchange (ETDEWEB)

Gomes, Tânia, E-mail: tania.gomes@niva.no; Chora, Suze; Pereira, Catarina G.; Cardoso, Cátia; Bebianno, Maria João

2014-10-15

Highlights: • Different protein expression patterns, tissue and Cu form dependent. • Different cellular mechanisms involved in CuO NPs and Cu{sup 2+} toxicity. • CuO NPs toxicity mediated by cell signalling cascades that result in apoptosis. • Caspase 3/7–1, catL, Zn-finger, precol-D as new molecular targets for both Cu forms in mussels. - Abstract: CuO NPs are one of the most used metal nanomaterials nowadays with several industrial and other commercial applications. Nevertheless, less is known about the mechanisms by which these NPs inflict toxicity in mussels and to what extent it differs from Cu{sup 2+}. The aim of this study was to investigate changes in protein expression profiles in mussels Mytilus galloprovincialis exposed for 15 days to CuO NPs and Cu{sup 2+} (10 μg L{sup −1}) using a proteomic approach. Results demonstrate that CuO NPs and Cu{sup 2+} induced major changes in protein expression in mussels’ showing several tissue and metal-dependent responses. CuO NPs showed a higher tendency to up-regulate proteins in the gills and down-regulate in the digestive gland, while Cu{sup 2+} showed the opposite tendency. Distinctive sets of differentially expressed proteins were found, either common or specific to each Cu form and tissue, reflecting different mechanisms involved in their toxicity. Fifteen of the differentially expressed proteins from both tissues were identified by MALDI-TOF-TOF. Identified proteins indicate common response mechanisms induced by CuO NPs and Cu{sup 2+}, namely in cytoskeleton and cell structure (actin, α-tubulin, paramyosin), stress response (heat shock cognate 71, putative C1q domain containing protein), transcription regulation (zinc-finger BED domain-containing protein 1, nuclear receptor subfamily 1G) and energy metabolism (ATP synthase F0 subunit 6). CuO NPs alone also had a marked effect on other biological processes, namely oxidative stress (GST), proteolysis (cathepsin L) and apoptosis (caspase 3/7-1). On

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

Enhancement of TiO2 NPs Activity by Fe3O4 Nano-Seeds for Removal of Organic Pollutants in Water

Directory of Open Access Journals (Sweden)

Silvia Villa

2016-09-01

Full Text Available The enhancement of the photocatalytic activity of TiO2 nanoparticles (NPs, synthesized in the presence of a very small amount of magnetite (Fe3O4 nanoparticles, is here presented and discussed. From X-ray diffraction (XRD and differential scanning calorimetry (DSC analyses, the crystallinity of TiO2 nanoparticles (NPs seems to be affected by Fe3O4, acting as nano-seeds to improve the tetragonal TiO2 anatase structure with respect to the amorphous one. Photocatalytic activity data, i.e., the degradation of methylene blue and the Ofloxacin fluoroquinolone emerging pollutant, give evidence that the increased crystalline structure of the NPs, even if correlated to a reduced surface to mass ratio (with respect to commercial TiO2 NPs, enhances the performance of this type of catalyst. The achievement of a relatively well-defined crystal structure at low temperatures (Tmax = 150 °C, preventing the sintering of the TiO2 NPs and, thus, preserving the high density of active sites, seems to be the keystone to understand the obtained results.

Trophic transfer potential of two different crystalline phases of TiO2 NPs from Chlorella sp. to Ceriodaphnia dubia.

Science.gov (United States)

Iswarya, V; Bhuvaneshwari, M; Chandrasekaran, N; Mukherjee, Amitava

2018-04-01

Owing to the increase in the usage of titanium dioxide nanoparticles (TiO 2 NPs), their release into the aquatic environment is inevitable. In the aquatic ecosystem, TiO 2 NPs can bio-magnify at various trophic levels in the food chain through dietary exposure. In the current study, the trophic transfer potential of two crystalline phases of TiO 2, anatase and rutile nanoparticles (individual as well as a binary mixture) has been evaluated in the lake water matrix using algae-daphnia system. Chlorella sp. and Ceriodaphnia dubia were used as test organisms to represent the algae-daphnia food chain of the freshwater ecosystem. Other than crystallinity, the effect of irradiation (visible and UV-A) was also investigated at the test concentrations, 75, 300, and 1200 μM. TiO 2 NPs treated algal diet produced significant mortality only at the test concentrations, 300 and 1200 μM. The type of irradiation and crystallinity doesn't have any impact on the mortality of daphnids through the dietary exposure of TiO 2 NPs. Comparing the mixture with individual NPs, binary mixture induced less mortality on C. dubia which signifies the antagonistic effect of NPs when they coexist. Statistical modeling confirmed the antagonistic effect of the binary mixture on C. dubia. As individual NPs, anatase and rutile forms showed a maximum Ti accumulation under UV-A and visible irradiation, respectively. BMF of TiO 2 NPs has been in validation with the bioaccumulation noted in C. dubia. Individual NPs (75 μM) showed higher BMF value of ∼23 under both UV-A (anatase) and visible (rutile) irradiation. Individual NPs showing higher BMF confirmed their trophic transfer potential in the aquatic food chain, primarily through the diet. In contrast, the binary mixture obtained a higher BMF of 1.9 and 0.79 at 75 and 300 μM under visible and UV-A irradiation, respectively. The plausible reason behind this decrement was the antagonistic effect of the mixture which significantly reduced

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.

Toxicity and trophic transfer of P25 TiO2 NPs from Dunaliella salina to Artemia salina: Effect of dietary and waterborne exposure.

Science.gov (United States)

Bhuvaneshwari, M; Thiagarajan, Vignesh; Nemade, Prateek; Chandrasekaran, N; Mukherjee, Amitava

2018-01-01

The recent increase in nanoparticle (P25 TiO 2 NPs) usage has led to concerns regarding their potential implications on environment and human health. The food chain is the central pathway for nanoparticle transfer from lower to high trophic level organisms. The current study relies on the investigation of toxicity and trophic transfer potential of TiO 2 NPs from marine algae Dunaliella salina to marine crustacean Artemia salina. Toxicity was measured in two different modes of exposure such as waterborne (exposure of TiO 2 NPs to Artemia) and dietary exposure (NP-accumulated algal cells are used to feed the Artemia). The toxicity and accumulation of TiO 2 NPs in marine algae D. salina were also studied. Artemia was found to be more sensitive to TiO 2 NPs (48h LC 50 of 4.21mgL -1 ) as compared to marine algae, D. salina (48h LC 50 of 11.35mgL -1 ). The toxicity, uptake, and accumulation of TiO 2 NPs were observed to be more in waterborne exposure as compared to dietary exposure. Waterborne exposure seemed to cause higher ROS production and antioxidant enzyme (SOD and CAT) activity as compared to dietary exposure of TiO 2 NPs in Artemia. There were no observed biomagnification (BMF) and trophic transfer from algae to Artemia through dietary exposure. Histopathological studies confirmed the morphological and internal damages in Artemia. This study reiterates the possible effects of the different modes of exposure on trophic transfer potential of TiO 2 NPs and eventually the consequences on aquatic environment. Copyright © 2017 Elsevier Inc. All rights reserved.

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+

Effect of heat treatment on the physical properties of bimetallic doped catalyst, Cu-Ni/TiO2

International Nuclear Information System (INIS)

Bashiri, Robabeh; Sufian, Suriati; Mohamed, Norani Muti; Kait, Chong Fai

2015-01-01

Post heat treatment is critical for the doped semiconductor oxide in order to improve its photocatalytic performance. Thus work had been carried out to understand the effect of different calcination temperature (400, 450 and 500°C) on the physical properties of nanosized Cu-Ni/TiO 2 Cu-Ni doped TiO 2 nanoparticles prepared using a combined method of sol-gel and hydrothermal. The treated samples were characterized using Raman spectroscopy, Brunauer–Emmett–teller (BET) measurement, high resolution transmission electron microscopy (HRTEM), field-emission scanning electron microscopy (FESEM), and diffuse reflectance UV-Vis spectroscopy (DR-UV-Vis). Raman analysis showed that all samples displayed anatase (101) phase of TiO 2 , which is in good agreement with the TEM results. BET data showed that all prepared Cu-Ni/TiO 2 with different calcination temperature are mesoporous. SEM images displayed spherical particles with typical size of about 15 to 20 nm. UV-Vis spectra illustrated that the absorbance edge of all prepared Cu-Ni/TiO 2 have extended to the visible region with bandgap energies (2-2.1 eV) less than the pure anatase TiO 2 (3.2 eV). Calcination temperature of 450°C is considered to be the optimum as it converts the synthesized Cu-Ni/TiO 2 sample to have smaller average particle size with higher surface area that lead to more absorbance in the visible region and lower bandgap energy

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.

Deep-level transient spectroscopy of TiO2/CuInS2 heterojunctions

NARCIS (Netherlands)

Nanu, M.; Boulch, F.; Schoonman, J.; Goossens, A.

2005-01-01

Deep-level transient spectroscopy (DLTS) has been used to measure the concentration and energy position of deep electronic states in CuInS2. Flat TiO2?CuInS2 heterojunctions as well as TiO2-CuInS2 nanocomposites have been investigated. Subband-gap electronic states in CuInS2 films are mostly due to

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.

Structural and vibrational investigations of Nb-doped TiO2 thin films

International Nuclear Information System (INIS)

Uyanga, E.; Gibaud, A.; Daniel, P.; Sangaa, D.; Sevjidsuren, G.; Altantsog, P.; Beuvier, T.; Lee, Chih Hao; Balagurov, A.M.

2014-01-01

Highlights: • We studied the evolutions of structure for TiO 2 thin film as changes with Nb doping and temperatures. • Up to 800 °C, the grain size of Nb 0.1 Ti 0.9 O 2 is smaller than for pure TiO 2 because doped Nb hinders the growth of the TiO 2 grains. • There was no formation of the rutile phase at high temperature. • Nb doped TiO 2 films have high electron densities at 400–700 °C. • Nb dope extends the absorbance spectra of TiO 2 which leads to the band gap reduce. - Abstract: Acid-catalyzed sol–gel and spin-coating methods were used to prepare Nb-doped TiO 2 thin film. In this work, we studied the effect of niobium doping on the structure, surface, and absorption properties of TiO 2 by energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray reflectometry (XRR), X-ray photoelectron spectroscopy (XPS), Raman, and UV–vis absorption spectroscopy at various annealing temperatures. EDX spectra show that the Nb:Ti atomic ratios of the niobium-doped titania films are in good agreement with the nominal values (5 and 10%). XPS results suggest that charge compensation is achieved by the formation of Ti vacancies. Specific niobium phases are not observed, thus confirming that niobium is well incorporated into the titania crystal lattice. Thin films are amorphous at room temperature and the formation of anatase phase appeared at an annealing temperature close to 400 °C. The rutile phase was not observed even at 900 °C (XRD and Raman spectroscopy). Grain sizes and electron densities increased when the temperature was raised. Nb-doped films have higher electron densities and lower grain sizes due to niobium doping. Grain size inhibition can be explained by lattice stress induced by the incorporation of larger Nb 5+ ions into the lattice. The band gap energy of indirect transition of the TiO 2 thin films was calculated to be about 3.03 eV. After niobium doping, it decreased to 2.40 eV

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.

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 of TiO2-doped SiO2 composite films and its applications

Indian Academy of Sciences (India)

Wintec

structure of the titanium oxide species in the TiO2-doped SiO2 composite films and the photocatalytic reactiv- ity in order to ... gaku D-max γA diffractometer with graphite mono- chromized ... FT–IR absorption spectra of TiO2-doped SiO2 com-.

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.

Origin of visible-light sensitivity in N-doped TiO2 films

International Nuclear Information System (INIS)

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

2007-01-01

We report on visible-light sensitivity in N-doped TiO 2 (TiO 2 :N) films that 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 by X-ray photoelectron spectroscopy measurements. From transmission electron microscopic observations and optical absorption measurements, yellow-colored TiO 2 :N samples showed an enhanced granular structure and strong absorption in the visible-light region. Photoelectron spectroscopy in air measurements showed a noticeable decrease in ionization energy of TiO 2 by the N doping. 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. The pronounced 2.48 eV band is newly introduced by the N doping and contributes to band-gap narrowing of TiO 2 by mixing with the O 2p valence band. Therefore, this localized intraband is probably one origin of visible-light sensitivity in TiO 2 :N

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

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%.

TiO2/Cu2O composite based on TiO2 NTPC photoanode for photoelectrochemical (PEC) water splitting under visible light

KAUST Repository

Shi, Le

2015-05-01

Water splitting through photoelectrochemical reaction is widely regarded as a major method to generate H2 , a promising source of renewable energy to deal with the energy crisis faced up to human being. Efficient exploitation of visible light in practice of water splitting with pure TiO2 material, one of the most popular semiconductor material used for photoelectrochemical water splitting, is still challenging. One dimensional TiO2 nanotubes is highly desired with its less recombination with the short distance for charge carrier diffusion and light-scattering properties. This work is based on TiO2 NTPC electrode by the optimized two-step anodization method from our group. A highly crystalized p-type Cu2O layer was deposited by optimized pulse potentiostatic electrochemical deposition onto TiO2 nanotubes to enhance the visible light absorption of a pure p-type TiO2 substrate and to build a p-n junction at the interface to improve the PEC performance. However, because of the real photocurrent of Cu2O is far away from its theoretical limit and also poor stability in the aqueous environment, a design of rGO medium layer was added between TiO2 nanotube and Cu2O layer to enhance the photogenerated electrons and holes separation, extend charge carrier diffusion length (in comparison with those of conventional pure TiO2 or Cu2O materials) which could significantly increase photocurrent to 0.65 mA/cm2 under visible light illumination (>420 nm) and also largely improve the stability of Cu2O layer, finally lead to an enhancement of water splitting performance.

Integrated photooxidative extractive deep desulfurization using metal doped TiO2 and eutectic based ionic liquid

Science.gov (United States)

Zaid, Hayyiratul Fatimah Mohd; Kait, Chong Fai; Mutalib, Mohamed Ibrahim Abdul

2016-11-01

A series of metal doped TiO2 namely Fe/TiO2, Cu/TiO2 and Cu-Fe/TiO2 were synthesized and characterized, to be used as a photocatalyst in the integrated photooxidative extractive deep desulfurization for model oil (dodecane) and diesel fuel. The order of the photocatalytic activity was Cu-Fe/TiO2 followed by Cu/TiO2 and then Fe/TiO2. Cu-Fe/TiO2 was an effective photocatalyst for sulfur conversion at ambient atmospheric pressure. Hydrogen peroxide was used as the source of oxidant and eutectic-based ionic liquid as the extractant. Sulfur conversion in model oil reached 100%. Removal of sulfur from model oil was done by two times extraction with a removal of 97.06% in the first run and 2.94% in the second run.

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%).

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

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

Transmission electron microscopy of carbon-coated and iron-doped titania nanoparticles

KAUST Repository

Anjum, Dalaver H.

2016-08-02

We present a study on the properties of iron (Fe)-doped and carbon (C)-coated titania (TiO2) nanoparticles (NPs) which has been compiled by using x-ray diffraction (XRD), transmission electron microscopy (TEM), and x-ray photoelectron spectroscopy (XPS). These TiO2 NPs were prepared by using the flame synthesis method. This method allows the simultaneous C coating and Fe doping of TiO2 NPs. XRD investigations revealed that the phase of the prepared NPs was anatase TiO2. Conventional TEM analysis showed that the average size of the TiO2 NPs was about 65 nm and that the NPs were uniformly coated with the element C. Furthermore, from the x-ray energy dispersive spectrometry analysis, it was found that about 8 at.% Fe was present in the synthesized samples. High-resolution TEM (HRTEM) revealed the graphitized carbon structure of the layer surrounding the prepared TiO2 NPs. HRTEM analysis further revealed that the NPs possessed the crystalline structure of anatase titania. Energy-filtered TEM (EFTEM) analysis showed the C coating and Fe doping of the NPs. The ratio of L3 and L2 peaks for the Ti-L23 and Fe-L23 edges present in the core loss electron energy loss spectroscopy (EELS) revealed a +4 oxidation state for the Ti and a +3 oxidation state for the Fe. These EELS results were further confirmed with XPS analysis. The electronic properties of the samples were investigated by applying Kramers-Kronig analysis to the low-loss EELS spectra acquired from the prepared NPs. The presented results showed that the band gap energy of the TiO2 NPs decreased from an original value of 3.2 eV to about 2.2 eV, which is quite close to the ideal band gap energy of 1.65 eV for photocatalysis semiconductors. The observed decrease in band gap energy of the TiO2 NPs was attributed to the presence of Fe atoms at the lattice sites of the anatase TiO2 lattice. In short, C-coated and Fe-doped TiO2 NPs were synthesized with a rather cost-effective and comparatively easily scalable method. The

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.

Facile fabrication of p-n heterojunctions for Cu2O submicroparticles deposited on anatase TiO2 nanobelts

International Nuclear Information System (INIS)

Li, Li; Lei, Jingguo; Ji, Tianhao

2011-01-01

Graphical abstract: Cu 2 O particle-deposited TiO 2 nanobelts with p-n semiconductor heterojunction structure were successfully prepared via two-step preparation process, and their visible-light photodegradation activities of Rhodamine B were investigated in detail. Highlights: → Cu 2 O particle-deposited TiO 2 nanobelts mainly with diameters in a range of 200-400 nm were successfully prepared. → The amount of Cu 2 O particles deposited on TiO 2 nanobelts can be tuned. → The composite structure with Cu 2 O particles and TiO 2 nanobelts exhibits p-n semiconductor heterojunction performance. → Photocatalytic properties of such composites. -- Abstract: In this paper, Cu 2 O particle-deposited TiO 2 nanobelts with p-n semiconductor heterojunction structure were successfully prepared via a two-step preparation process to investigate electron-transfer performance between p-type Cu 2 O and n-type TiO 2 . Various measurement results confirm that the amount of pure Cu 2 O submicroparticles, with diameters within the range of 200-400 nm and deposited on the surface of TiO 2 nanobelts, can be controlled, and that the purity of Cu 2 O is heavily affected by reaction time. Visible-light photodegradation activities of Rhodamine B show that photocatalysts have little or no photocatalytic activities mainly due to their p-n heterojunction structure, indicating that there hardly appears any electron-transfer from Cu 2 O to TiO 2 .

Effects of highly ordered TiO2 nanotube substrates on the nucleation of Cu electrodeposits.

Science.gov (United States)

Ryu, Won Hee; Park, Chan Jin; Kwon, Hyuk Sang

2010-05-01

We investigated the effects of TiO2 nanotube substrates on the nucleation density of Cu during electrodeposition in a solution of CuSO4 and H2SO4 at 50 degrees C compared with those of pure Ti and micro-porous TiO2 substrates. During electrodeposition, the density of Cu nuclei on the TiO2 nanotube substrate increased and the average size of Cu nuclei decreased with increasing anodizing voltage and time for the synthesis of the substrate. In addition, the nucleation density of Cu electrodeposits on the highly ordered TiO2 nanotube substrate was much higher than that on pure Ti and micro-porous TiO2 substrates.

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.

Transparent nanostructured Fe-doped TiO2 thin films prepared by ultrasonic assisted spray pyrolysis technique

Science.gov (United States)

Rasoulnezhad, Hossein; Hosseinzadeh, Ghader; Ghasemian, Naser; Hosseinzadeh, Reza; Homayoun Keihan, Amir

2018-05-01

Nanostructured TiO2 and Fe-doped TiO2 thin films with high transparency were deposited on glass substrate through ultrasonic-assisted spray pyrolysis technique and were used in the visible light photocatalytic degradation of MB dye. The resulting thin films were characterized by scanning electron microscopy (SEM), Raman spectroscopy, photoluminescence spectroscopy, x-ray diffraction (XRD), and UV-visible absorption spectroscopy techniques. Based on Raman spectroscopy results, both of the TiO2 and Fe-doped TiO2 films have anatase crystal structure, however, because of the insertion of Fe in the structure of TiO2 some point defects and oxygen vacancies are formed in the Fe-doped TiO2 thin film. Presence of Fe in the structure of TiO2 decreases the band gap energy of TiO2 and also reduces the electron–hole recombination rate. Decreasing of the electron–hole recombination rate and band gap energy result in the enhancement of the visible light photocatalytic activity of the Fe-doped TiO2 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.

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.

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

STRUKTUR MORFOLOGI, KOMPOSISI KIMIA DAN RESISTANSI LAPISAN TIO2-CU SEBAGAI LAPISAN AKTIF PADA SEL SURYA FOTOELEKTROKIMIA

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Rita Prasetyowati

2013-11-01

Full Text Available Peningkatan efisiensi sel surya titania terus dikembangkan. Salah satunya adalah memodifikasi titania yang berfungsi sebagai lapisan aktif. Lapisan titania dapat disisipi dengan logam Cu. Penyisipan logam Cu pada TiO2 dilakukan melalui pembuatan nanokomposit TiO2-Cu dengan metode sol-gel. Lapisan TiO2-Cu yang terbentuk dikarakterisasi dengan SEM (Scanning Electron Microscopy untuk mengetahui struktur morfologi permukaan, EDX (Energy dispersive X-ray spectroscopy untuk mengetahui komposisi bahan. Sedangkan resistansi lapisan diukur menggunakan Jembatan Wheatstone. Berdasarkan hasil SEM dapat ditunjukkan bahwa struktur morfologi permukaan lapisan TiO2-Cu tidak berbeda secara signifikan dengan lapisan TiO2, yaitu cukup homogen dan memiliki ukuran butir (grain yang hampir sama. Tetapi dari hasil EDX diperoleh bahwa lapisan TiO2-Cu yaitu lapisan TiO2 yang disisipi logam tembaga mengandung  unsur Ti sebanyak 59,8%, unsur O sebanyak 40,02% dan unsur Cu sebanyak 0,19%. Sedangkan lapisan TiO2 saja mengandung unsur Ti sebanyak 54,25% dan unsur O sebanyak 45,75%. Penyisipan logam tembaga pada lapisan titania dapat menurunkan resistansi listrik lapisan. Nilai resistansi lapisan TiO2 adalah 7,714 kilo ohm. Sedangkan nilai resistansi lapisan TiO2-Cu adalah 6,624 kilo ohm.

Fabrication of doped TiO2 nanotube array films with enhanced photo-catalytic activity

Science.gov (United States)

Peighambardoust, Naeimeh-Sadat; Khameneh-asl, Shahin; Khademi, Adib

2018-01-01

In the present work, we investigate the N and Fe-doped TiO2 nanotube array film prepared by treating TiO2 nanotube array film with ammonia solution and anodizing in Fe(NO3)3 solution respectively. This method avoided the use of hazardous ammonia gas, or laborious ion implantation process. N and Fe-doped TiO2 nanotube arrays (TiO2 NTs) were prepared by electrochemical anodization process in 0.5 wt % HF aqueous solution. The anodization was performed at the conditions of 20 V and 20 min, Followed by a wet immersion in NH3.H2O (1M) for N-doping for 2 hr and annealing post-treatment at 450 °C. The morphology and structure of the nanotube films were characterized by field emission scanning electron microscope (FESEM) and EDX. UV-vis. illumination test were done to observe photo-enhanced catalysis. The effect of different annealing temperature on the structure and photo-absorption property of the TiO2-TNTs was investigated. The results showed that N-TNTs nanotubes exhibited higher photocatalytic activity compared whit the Fe-doped and pure TNTs, because doping N promoted the separation of the photogenerated electrons and holes.

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.

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

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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.

Non-noble metal Cu-loaded TiO2 for enhanced photocatalytic H2 production.

Science.gov (United States)

Foo, Wei Jian; Zhang, Chun; Ho, Ghim Wei

2013-01-21

Here we have demonstrated the preparation of high-quality, monodispersed and tunable phases of Cu nanoparticles. Structural and chemical composition studies depict the evolution of Cu-Cu(2)O-CuO nanoparticles at various process stages. The loading of Cu and Cu oxide nanoparticles on TiO(2) catalyst has enhanced the photocatalytic H(2) production. Comparatively, H(2) treatment produces well-dispersed Cu nanoparticles with thin oxide shells that show the highest H(2) production amongst the samples. The relatively higher photocatalytic performance is deemed to result from reduced structural defects, higher surface area and dispersivity as well as favorable charge transfer, which inhibits recombination. The Cu nanoparticles are shown to be a promising alternative to noble metal-loaded TiO(2) catalyst systems due to their low cost and high performance in photocatalytic applications.

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

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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.

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.

Potential thermoelectric performance of hole-doped Cu2O

International Nuclear Information System (INIS)

Chen, Xin; Parker, David; Du, Mao-Hua; Singh, David J

2013-01-01

High thermoelectric performance in oxides requires stable conductive materials that have suitable band structures. Here we show, based on an analysis of the thermopower and related properties using first-principles calculations and Boltzmann transport theory in the relaxation time approximation, that hole-doped Cu 2 O may be such a material. We find that hole-doped Cu 2 O has a high thermopower of above 200 μV K −1 even with doping levels as high as 5.2 × 10 20 cm −3 at 500 K, mainly attributed to the heavy valence bands of Cu 2 O. This is reminiscent of the cobaltate family of high-performance oxide thermoelectrics and implies that hole-doped Cu 2 O could be an excellent thermoelectric material if suitably doped. (paper)

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

Fate of pristine TiO2 nanoparticles and aged paint-containing TiO2 nanoparticles in lettuce crop after foliar exposure.

Science.gov (United States)

Larue, Camille; Castillo-Michel, Hiram; Sobanska, Sophie; Trcera, Nicolas; Sorieul, Stéphanie; Cécillon, Lauric; Ouerdane, Laurent; Legros, Samuel; Sarret, Géraldine

2014-05-30

Engineered TiO2 nanoparticles (TiO2-NPs) are present in a large variety of consumer products, and are produced in largest amount. The building industry is a major sector using TiO2-NPs, especially in paints. The fate of NPs after their release in the environment is still largely unknown, and their possible transfer in plants and subsequent impacts have not been studied in detail. The foliar transfer pathway is even less understood than the root pathway. In this study, lettuces were exposed to pristine TiO2-NPs and aged paint leachate containing TiO2-NPs and microparticles (TiO2-MPs). Internalization and in situ speciation of Ti were investigated by a combination of microscopic and spectroscopic techniques. Not only TiO2-NPs pristine and from aged paints, but also TiO2-MPs were internalized in lettuce leaves, and observed in all types of tissues. No change in speciation was noticed, but an organic coating of TiO2-NPs is likely. Phytotoxicity markers were tested for plants exposed to pristine TiO2-NPs. No acute phytotoxicity was observed; variations were only observed in glutathione and phytochelatin levels but remained low as compared to typical values. These results obtained on the foliar uptake mechanisms of nano- and microparticles are important in the perspective of risk assessment of atmospheric contaminations. Copyright © 2014 Elsevier B.V. All rights reserved.

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.

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.

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.

Inverted organic solar cells with solvothermal synthesized vanadium-doped TiO2 thin films as efficient electron transport layer

Institute of Scientific and Technical Information of China (English)

Mehdi Ahmadi; Sajjad Rashidi Dafeh; Samaneh Ghazanfarpour; Mohammad Khanzadeh

2017-01-01

We investigated the effects of using different thicknesses of pure and vanadium-doped thin films of TiO2 as the electron transport layer in the inverted configuration of organic photovoltaic cells based on poly (3-hexylthiophene) P3HT:[6-6] phenyl-(6) butyric acid methyl ester (PCBM).1％ vanadium-doped TiO2 nanoparticles were synthesized via the solvothermal method.Crystalline structure,morphology,and optical properties of pure and vanadium-doped TiO2 thin films were studied by different techniques such as x-ray diffraction,scanning electron microscopy,transmittance electron microscopy,and UV-visible transmission spectrum.The doctor blade method which is compatible with roll-2-roll printing was used for deposition of pure and vanadium-doped TiO2 thin films with thicknesses of 30 nm and 60 nm.The final results revealed that the best thickness of TiO2 thin films for our fabricated cells was 30 nm.The cell with vanadium-doped TiO2 thin film showed slightly higher power conversion efficiency and great Jsc of 10.7 mA/cm2 compared with its pure counterpart.In the cells using 60 nm pure and vanadium-doped TiO2 layers,the cell using the doped layer showed much higher efficiency.It is remarkable that the extemal quantum efficiency of vanadium-doped TiO2 thin film was better in all wavelengths.

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.

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

Nitrogen and europium doped TiO2 anodized films with applications in photocatalysis

International Nuclear Information System (INIS)

Chi, Choong-Soo; Choi, Jinwook; Jeong, Yongsoo; Lee, Oh Yeon; Oh, Han-Jun

2011-01-01

Micro-arc oxidation method is a useful process for mesoporous titanium dioxide films. In order to improve the photocatalytic activity of the TiO 2 film, N-Eu co-doped titania catalyst was synthesized by micro-arc oxidation in the H 2 SO 4 /Eu(NO 3 ) 3 mixture solution. The specific surface area and the roughness of the anodic titania film fabricated in the H 2 SO 4 /Eu(NO 3 ) 3 electrolyte, were increased compared to that of the anodic TiO 2 film prepared in H 2 SO 4 solution. The absorbance response of N-Eu titania film shows a higher adsorption onset toward visible light region, and the incorporated N and Eu ions during anodization as a dopant in the anodic TiO 2 film significantly enhanced the photocatalytic activity for dye degradation. After dye decomposition test for 3 h, dye removal rates for the anodic TiO 2 film were 60.7% and 90.1% for the N-Eu doped titania film. The improvement of the photocatalytic activity was ascribed to the synergistic effects of the surface enlargement and the new electronic state of the TiO 2 band gap by N and Eu co-doping.

Toxicity of nanoparticles of CuO, ZnO and TiO2 to microalgae Pseudokirchneriella subcapitata.

Science.gov (United States)

Aruoja, Villem; Dubourguier, Henri-Charles; Kasemets, Kaja; Kahru, Anne

2009-02-01

Toxicities of ZnO, TiO2 and CuO nanoparticles to Pseudokirchneriella subcapitata were determined using OECD 201 algal growth inhibition test taking in account potential shading of light. The results showed that the shading effect by nanoparticles was negligible. ZnO nanoparticles were most toxic followed by nano CuO and nano TiO2. The toxicities of bulk and nano ZnO particles were both similar to that of ZnSO4 (72 h EC50 approximately 0.04 mg Zn/l). Thus, in this low concentration range the toxicity was attributed solely to solubilized Zn2+ ions. Bulk TiO2 (EC50=35.9 mg Ti/l) and bulk CuO (EC50=11.55 mg Cu/l) were less toxic than their nano formulations (EC50=5.83 mg Ti/l and 0.71 mg Cu/l). NOEC (no-observed-effect-concentrations) that may be used for risk assessment purposes for bulk and nano ZnO did not differ (approximately 0.02 mg Zn/l). NOEC for nano CuO was 0.42 mg Cu/l and for bulk CuO 8.03 mg Cu/l. For nano TiO2 the NOEC was 0.98 mg Ti/l and for bulk TiO2 10.1 mg Ti/l. Nano TiO2 formed characteristic aggregates entrapping algal cells that may contribute to the toxic effect of nano TiO2 to algae. At 72 h EC50 values of nano CuO and CuO, 25% of copper from nano CuO was bioavailable and only 0.18% of copper from bulk CuO. Thus, according to recombinant bacterial and yeast Cu-sensors, copper from nano CuO was 141-fold more bioavailable than from bulk CuO. Also, toxic effects of Cu oxides to algae were due to bioavailable copper ions. To our knowledge, this is one of the first systematic studies on effects of metal oxide nanoparticles on algal growth and the first describing toxic effects of nano CuO towards algae.

Low-temperature preparation of rutile-type TiO2 thin films for optical coatings by aluminum doping

Science.gov (United States)

Ishii, Akihiro; Kobayashi, Kosei; Oikawa, Itaru; Kamegawa, Atsunori; Imura, Masaaki; Kanai, Toshimasa; Takamura, Hitoshi

2017-08-01

A rutile-type TiO2 thin film with a high refractive index (n), a low extinction coefficient (k) and small surface roughness (Ra) is required for use in a variety of optical coatings to improve the controllability of the reflection spectrum. In this study, Al-doped TiO2 thin films were prepared by pulsed laser deposition, and the effects of Al doping on their phases, optical properties, surface roughness and nanoscale microstructure, including Al distribution, were investigated. By doping 5 and 10 mol%Al, rutile-type TiO2 was successfully prepared under a PO2 of 0.5 Pa at 350-600 °C. The nanoscale phase separation in the Al-doped TiO2 thin films plays an important role in the formation of the rutile phase. The 10 mol%Al-doped rutile-type TiO2 thin film deposited at 350 °C showed excellent optical properties of n ≈ 3.05, k ≈ 0.01 (at λ = 400 nm) and negligible surface roughness, at Ra ≈ 0.8 nm. The advantages of the superior optical properties and small surface roughness of the 10 mol%Al-doped TiO2 thin film were confirmed by fabricating a ten-layered dielectric mirror.

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 .

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.

Versatile preparation method for mesoporous TiO2 electrodes ...

Indian Academy of Sciences (India)

Unknown

cyanate into CuI layer further enhanced the efficiency up to 2⋅75% under the irradiance .... an extremely easy way to dope films with virtually any .... to see the effect of ionic liquid on CuI, 1-ethyl-3-methyl- ... This analysis showed that TiO2 electrodes were polycrys- .... thin insulating layer of Al2O3 by using dip-coating meth-.

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

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

Photocatalytic properties and selective antimicrobial activity of TiO2(Eu)/CuO nanocomposite

Science.gov (United States)

Michal, Robert; Dworniczek, Ewa; Caplovicova, Maria; Monfort, Olivier; Lianos, Panagiotis; Caplovic, Lubomir; Plesch, Gustav

2016-05-01

TiO2(Eu)/CuO nanocomposites were prepared by precipitation method. The anatase nanocrystallites with a size of 26 nm exhibited well crystallized and characteristical dipyramidal morphology and {1 0 1} and {0 0 1} faceting. Transmission electron microscopy photographs with atomic resolution showed that the Eu(III) dopants were bounded on surface of titania. In the composites, the CuO nanocrystals exhibiting a monoclinic tenorite structure with a size in the range from 2 to 5 nm were grafted to the surface of titania. The influence of copper(II) oxide led to distinct selectivity in the photocatalytic and antimicrobial properties of the investigated TiO2(Eu)/CuO nanocomposites. While the presence of CuO nanocrystals strongly increased the photocatalytic production of hydrogen by ethanol reforming, it decreased the activity in photoinduced total mineralization of phenol comparing with non-modified TiO2(Eu). In investigated TiO2(Eu)/CuO powders, the photoinduced antimicrobial activity against membranes of Enterococcus species was influenced by the selective binding of CuO to the surface of the microorganism leading to distinct selectivity in their action. The activity against Enterococcus faecalis was higher than against Enterococcus faecium.

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).

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

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

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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 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

Enhanced Charge Extraction of Li-Doped TiO2 for Efficient Thermal-Evaporated Sb2S3 Thin Film Solar Cells

Science.gov (United States)

Lan, Chunfeng; Luo, Jingting; Lan, Huabin; Fan, Bo; Peng, Huanxin; Zhao, Jun; Sun, Huibin; Zheng, Zhuanghao; Liang, Guangxing; Fan, Ping

2018-01-01

We provided a new method to improve the efficiency of Sb2S3 thin film solar cells. The TiO2 electron transport layers were doped by lithium to improve their charge extraction properties for the thermal-evaporated Sb2S3 solar cells. The Mott-Schottky curves suggested a change of energy band and faster charge transport in the Li-doped TiO2 films. Compared with the undoped TiO2, Li-doped mesoporous TiO2 dramatically improved the photo-voltaic performance of the thermal-evaporated Sb2S3 thin film solar cells, with the average power conversion efficiency (PCE) increasing from 1.79% to 4.03%, as well as the improved open-voltage (Voc), short-circuit current (Jsc) and fill factors. The best device based on Li-doped TiO2 achieved a power conversion efficiency up to 4.42% as well as a Voc of 0.645 V, which are the highest values among the reported thermal-evaporated Sb2S3 solar cells. This study showed that Li-doping on TiO2 can effectively enhance the charge extraction properties of electron transport layers, offering a new strategy to improve the efficiency of Sb2S3-based solar cells. PMID:29495612

Enhanced Charge Extraction of Li-Doped TiO2 for Efficient Thermal-Evaporated Sb2S3 Thin Film Solar Cells

Directory of Open Access Journals (Sweden)

Chunfeng Lan

2018-02-01

Full Text Available We provided a new method to improve the efficiency of Sb2S3 thin film solar cells. The TiO2 electron transport layers were doped by lithium to improve their charge extraction properties for the thermal-evaporated Sb2S3 solar cells. The Mott-Schottky curves suggested a change of energy band and faster charge transport in the Li-doped TiO2 films. Compared with the undoped TiO2, Li-doped mesoporous TiO2 dramatically improved the photo-voltaic performance of the thermal-evaporated Sb2S3 thin film solar cells, with the average power conversion efficiency (PCE increasing from 1.79% to 4.03%, as well as the improved open-voltage (Voc, short-circuit current (Jsc and fill factors. The best device based on Li-doped TiO2 achieved a power conversion efficiency up to 4.42% as well as a Voc of 0.645 V, which are the highest values among the reported thermal-evaporated Sb2S3 solar cells. This study showed that Li-doping on TiO2 can effectively enhance the charge extraction properties of electron transport layers, offering a new strategy to improve the efficiency of Sb2S3-based solar cells.

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)

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.

Antimicrobial activity and biocompatibility of Ag+- and Cu2+-doped biphasic hydroxyapatite/α-tricalcium phosphate obtained from hydrothermally synthesized Ag+- and Cu2+-doped hydroxyapatite

International Nuclear Information System (INIS)

Radovanović, Željko; Jokić, Bojan; Veljović, Djordje; Dimitrijević, Suzana; Kojić, Vesna; Petrović, Rada; Janaćković, Djordje

2014-01-01

Hydroxyapatite (HAp) powders doped with Ag + or Cu 2+ were synthesized by a hydrothermal method in order to obtain biomaterial with an antimicrobial effect. The synthesis was performed with two contents of dopant (Ag + or Cu 2+ ) by considering both the antimicrobial activities and biocompatibility of the powders. The doped HAp was annealed at 1200 °C for 2 h with the intention of investigating the influence of doping with Ag + and Cu 2+ on the creation of the biphasic HAp/α-tricalcium phosphate (HAp/α-TCP) and determining the antimicrobial activity and biocompatibility of the obtained biphasic powders. Analyses of all powders, undoped and doped HAp and HAp/α-TCP, were performed by Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), atomic absorption spectroscopy (AAS) and energy-dispersive X-ray spectroscopy (EDS). The in vitro antibacterial activities of the powders were evaluated against: Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. All powders showed good antimicrobial activity but generally the powders of doped HAp/α-TCP had more uniform results against all pathogenic microorganisms than the powders of doped HAp. In vitro biocompatibility tests, MTT and DET, were used to evaluate the biocompatibility of Ag + - and Cu 2+ -doped HAp/α-TCP with MRC-5 human fibroblast cells. These tests confirmed that powders do not have a cytotoxic effect. The HAp/α-TCP powders doped with the lower content of Ag + and Cu 2+ showed especially good biocompatibility. Antimicrobial and biocompatibility tests recommend the Ag + - and Cu 2+ -doped HAp/α-TCP as promising material for use in reconstructive surgery of bone.

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

Science.gov (United States)

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.

Ultrasound assisted synthesis of iron doped TiO2 catalyst.

Science.gov (United States)

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.

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.

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

International Nuclear Information System (INIS)

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)

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

Directory of Open Access Journals (Sweden)

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.

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).

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

International Nuclear Information System (INIS)

Tatlıdil, İlknur; Bacaksız, Emin; Buruk, Celal Kurtuluş; Breen, Chris; Sökmen, Münevver

2012-01-01

Highlights: ► Co or Fe doped TiO 2 thin films were prepared by sol–gel method. ► We obtained lower E g values for Fe-doped and Co-TiO 2 thin films. ► Doping greatly affected the size and shape of the TiO 2 nanoparticles. ► Photocatalytic killing effect of the doped TiO 2 thin films on C. albicans and A. niger was significantly higher than undoped TiO 2 thin film for short exposure periods. - Abstract: In this study, a short recent literature survey which concentrated on the usage of Fe 3+ or Co 2+ ion doped TiO 2 thin films and suspensions were summarized. Additionally, a sol–gel method was used for preparation of the 2% Co or Fe doped TiO 2 thin films. The surface of the prepared materials was characterised using scanning-electron microscopy (SEM) combined with energy dispersive X-ray (EDX) analysis and band gap of the films were calculated from the transmission measurements that were taken over the range of 190 and 1100 nm. The E g value was 3.40 eV for the pure TiO 2 , 3.00 eV for the Fe-doped TiO 2 film and 3.25 eV for Co-TiO 2 thin film. Iron or cobalt doping at lower concentration produce more uniformed particles and doping greatly affected the size and shape of the TiO 2 nanoparticles. Photocatalytic killing effect of the 2% Co doped TiO 2 thin film on Candida albicans was significantly higher than Fe doped TiO 2 thin film for short and long exposure periods. Doped thin films were more effective on Aspergillus niger for short exposure periods.

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

Science.gov (United States)

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

Parameters determining efficiency and degradation of TiO2 vertical bar dye vertical bar CuI solar cells

International Nuclear Information System (INIS)

Sirimanne, P.M.; Tributsch, Helmut

2004-01-01

The influence of the micro-morphological structure of the TiO 2 film, the distribution of CuI in TiO 2 pores and the concentration of added surfactant in the CuI coating solution on the photocurrent of solid-state TiO 2 vertical bar dye vertical bar CuI solar cells was examined by space resolved photocurrent imaging technique. Iodine is found to be competing with the oxidized dye molecules in accepting electrons from CuI and decreases the efficiency of the cell. TiO 2 vertical bar dye vertical bar CuI cell degrade two hundred times faster than wet sensitization cells. This instability is considered to be due to the decomposition of the electron transfer-bridge between the sensitizer and CuI

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.

Influence of substrate temperature and silver-doping on the structural and optical properties of TiO_2 films

International Nuclear Information System (INIS)

Fischer, Dieter

2016-01-01

Evaporation of titanium together with activated oxygen is used to grow TiO_2 films and simultaneously with silver to grow Ag–TiO_2 films (5 at.% Ag) onto sapphire substrates at three different substrate temperatures: − 190, 30, and 200 °C. The obtained films were characterized by X-ray powder diffraction, Raman, X-ray photoelectron, ultraviolet–visible spectroscopy, and transmission electron microscope investigations. The properties of TiO_2 films varied with the substrate temperature. Amorphous, transparent TiO_2 films were grown at − 190 °C and opaque, polycrystalline films at 200 °C, respectively. Surprisingly, at room temperature black, amorphous TiO_2 films are obtained which transform at 350 °C into a mixture of the anatase and brookite polymorph. In the amorphous state of the TiO_2 films a predefined rutile arrangement is suggested by Raman investigations, and the contraction of the lattice constant c of anatase phases (tetragonal, space group I 4_1/amd) depending on the substrate temperature is experimentally observed. The silver-doped TiO_2 films deposited at − 190 and 30 °C contain Ag-particles with 2 nm in size inside the TiO_2 matrix, which after annealing segregate under increasing particle sizes. The silver-doping stabilizes the anatase polymorph and yields to reduced titanium species in the films especially during deposition at 30 °C. The Ag–TiO_2 films deposited at − 190 °C are transparent up to 350 °C. In the undoped as well as silver-doped TiO_2 films the rutile polymorph is directly formed at 200 °C as main phase. - Highlights: • At room temperature black, amorphous TiO_2 films are obtained. • A predefined rutile arrangement is suggested in amorphous TiO_2 films. • Annealed TiO_2 films crystallize to a mixture of the anatase and brookite polymorph. • In TiO_2 and Ag-doped TiO_2 films the rutile polymorph is directly formed at 200 °C. • Ag-doped TiO_2 films stabilize the anatase polymorph and reduced titanium

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

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.

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

Science.gov (United States)

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.

Local Electrical Response in Alkaline-Doped Electrodeposited CuInSe2/Cu Films

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Javier A. Barón-Miranda

2016-12-01

Full Text Available The local electrical response in alkaline-doped CuInSe2 films prepared by single-step electrodeposition onto Cu substrates was studied by current-sensing atomic force microscopy. The CuInSe2 (CIS films were prepared from single baths containing the dopant ions (Li, Na, K or Cs and were studied by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and photocurrent response. Increased crystallinity and surface texturing as the ion size increased were observed, as well as an enhanced photocurrent response in Cs-doped CIS. Li- and Na-doped films had larger conductivity than the undoped film while the K- and Cs-doped samples displayed shorter currents and the current images indicated strong charge accumulation in the K- and Cs-doped films, forming surface capacitors. Corrected current-sensing AFM IV curves were adjusted with the Shockley equation.

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%).

Optical and structural properties of Cu-doped β-Ga2O3 films

International Nuclear Information System (INIS)

Zhang Yijun; Yan Jinliang; Li Qingshan; Qu Chong; Zhang Liying; Xie Wanfeng

2011-01-01

Graphical abstract: Highlights: → We prepare polycrystalline Cu-doped β-Ga2O3 films. → Cu dopants cause poor crystal quality and shrinkage of the optical band gap. → Cu-doping enhances the UV and blue emission. → A new blue emission peak centre at 475 nm appears by Cu-doping. → Cu dopants decrease the optical transmittance. - Abstract: The intrinsic and Cu-doped β-Ga 2 O 3 films were grown on Si and quartz substrates by RF magnetron sputtering in an argon and oxygen mixture ambient. The effects of the Cu doping and the post thermal annealing on the optical and structural properties of the β-Ga 2 O 3 films were studied. The surface morphology, microstructure, optical transmittance, optical absorption, optical energy gap and photoluminescence of the β-Ga 2 O 3 films were significantly changed after Cu-doping. After post thermal annealing, Polycrystalline β-Ga 2 O 3 films were obtained, the transmittance decreased. After Cu-doping, the grain size decreased, the crystal quality deteriorated and the optical band gap shrunk. The UV, blue and green emission bands were observed and discussed. The UV and blue emission were enhanced and a new blue emission peak centred at 475 nm appeared by Cu-doping.

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 .

Enhancement of photocatalytic degradation of polyethylene plastic with CuPc modified TiO2 photocatalyst under solar light irradiation

International Nuclear Information System (INIS)

Zhao Xu; Li Zongwei; Chen Yi; Shi Liyi; Zhu Yongfa

2008-01-01

Solid-phase photocatalytic degradation of polyethylene (PE) plastic, one of the most common commercial plastic, over copper phthalocyanine (CuPc) modified TiO 2 (TiO 2 /CuPc) photocatalyst was investigated in the ambient air under solar light irradiation. Higher PE weight loss rate, greater texture change; more amount of generated CO 2 , which is the main product of the photocatalytic degradation of the composite PEC plastic can be achieved in the system of PE-(TiO 2 /CuPc) in comparison with PE-TiO 2 system. The CuPc promoted charge separation of TiO 2 and enhanced the photocatalytic degradation of PE based on the analysis of surface photovoltage spectroscopy (SPS). During the photodegradation of PE plastic, the reactive oxygen species generated on TiO 2 or TiO 2 /CuPc particle surfaces play important roles. The present study demonstrates that the combination of polymer plastic with TiO 2 /CuPc composite photocatalyst in the form of thin film is a practical and useful way to photodegrade plastic contaminants under solar light irradiation

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

Science.gov (United States)

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.

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

Enhanced photoelectrocatalytic performance for degradation of diclofenac and mechanism with TiO2 nano-particles decorated TiO2 nano-tubes arrays photoelectrode

International Nuclear Information System (INIS)

Cheng, Xiuwen; Liu, Huiling; Chen, Qinghua; Li, Junjing; Wang, Pu

2013-01-01

In this study, TiO 2 nano-particles decorated TiO 2 nano-tubes arrays (TiO 2 NPs/TiO 2 NTAs) photoelectrodes have been successfully prepared through anodization, combined with ultrasonic strategy, followed by annealing post-treatment. The morphology and structure of the as-prepared TiO 2 NPs/TiO 2 NTAs photoelectrodes were characterized by scanning electrons microscopy (SEM), N 2 adsorption/desorption isotherms, X-ray diffraction (XRD) and UV–visible light diffuse reflection spectroscopy (DRS). In addition, the generation of hydroxyl radicals (·OH) was detected by a photoluminescence (PL) spectra using terephthalic acid (TA) as a probe molecule. Furthermore, the photoelectrochemical (PECH) properties of TiO 2 NPs/TiO 2 NTAs photoanode were investigated through transient open circuit potential (OCP), photocurrent response (PCR) and electrochemical impedance spectroscopy (EIS). It was found that TiO 2 NPs/TiO 2 NTAs photoelectrode exhibited a distinct decrease of OCP of −0.219 mV cm −2 and PCR of 0.049 mA cm −2 , while a significantly enhanced photoelectrocatalytic (PEC) efficiency of 63.6% (0.4 V vs. SCE) for the degradation of diclofenac. Moreover, the enhanced PEC mechanism of TiO 2 NPs/TiO 2 NTAs photoanode was proposed. The high PEC performance could be attributed to the decoration of TiO 2 NPs, which could improve the mobility and separation efficiency of photoinduced charge carriers under external potential

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.

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

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Fatma Pınar Gökdemir

2014-01-01

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

The Photovoltaic Performance of Doped-CuI Hole Conductors for Solid State Dye-Sensitized Solar Cells

International Nuclear Information System (INIS)

Amalina, M N; Najwa, A A E; Abdullah, M H; Musa, M Z; Rusop, M

2013-01-01

The iodine doped copper (I) iodide (I 2 : CuI) at different weight of iodine dopant have been prepared to investigate its thin films properties and photovoltaic performance. A novel method of mist atomization technique has been used for the deposition of CuI materials. The structural and electrical properties of CuI thin films deposited on the glass substrates were studied. The thin films morphology examined by FESEM shows a variation of crystal size and structure. Brick-like structure with smooth faces and sharp edges were seen for the doped thin films. The CuI thin films at 30 mg of iodine doping shows the highest resistivity of 4.56 × 101 Ω cm which caused by the surface traps create by iodine doping. The photovoltaic performance of ss-DSSC on the effect of variation iodine doping was investigated. The ss-DSSC fabricated with undoped CuI materials shows the highest efficiency of 1.05% while the 40 mg I 2 content shows the lowest conversion efficiency of 0.45%. The crystals size of CuI and its degree of crystallization are greatly contributed to the high filling fraction of the porous TiO 2 layer and hence the cells performance.

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.

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

TiO2 film/Cu2O microgrid heterojunction with photocatalytic activity under solar light irradiation.

Science.gov (United States)

Zhang, Junying; Zhu, Hailing; Zheng, Shukai; Pan, Feng; Wang, Tianmin

2009-10-01

Coupling a narrow-band-gap semiconductor with TiO(2) is an effective method to produce photocatalysts that work under UV-vis light irradiation. Usually photocatalytic coupled-semiconductors exist mainly as powders, and photocatalytic activity is only favored when a small loading amount of narrow-band-gap semiconductor is used. Here we propose a heavy-loading photocatalyst configuration in which 51% of the surface of the TiO(2) film is covered by a Cu(2)O microgrid. The coupled system shows higher photocatalytic activity under solar light irradiation than TiO(2) and Cu(2)O films. This improved performance is due to the efficient charge transfer between the two phases and the similar opportunity each has to be exposed to irradiation and adsorbates.

Distinct toxic interactions of TiO2 nanoparticles with four coexisting organochlorine contaminants on algae.

Science.gov (United States)

Zhang, Shuai; Deng, Rui; Lin, Daohui; Wu, Fengchang

Engineered nanoparticles are increasingly discharged into the environment. After discharge, these nanoparticles can interact with co-existing organic contaminants, resulting in a phenomena referred to as 'joint toxicity'. This study evaluated joint toxicities of TiO 2 nanoparticles (TiO 2 NPs) with four different (atrazine, hexachlorobenzene, pentachlorobenzene, and 3,3',4,4'-tetrachlorobiphenyl) organochlorine contaminants (OCs) toward algae (Chlorella pyrenoidosa). The potential mechanisms underlying the joint toxicity were discussed, including TiO 2 NPs-OC interactions, effects of TiO 2 NPs and OCs on biophysicochemical properties of algae and effects of TiO 2 NPs and OCs on each other's bioaccumulation in algae. The results indicate that coexposure led to a synergistic effect on the joint toxicity for TiO 2 NPs-atrazine, antagonistic effect for TiO 2 NPs-hexachlorobenzene and TiO 2 NPs-3,3',4,4'-tetrachlorobiphenyl, and an additive effect for TiO 2 NPs-pentachlorobenzene. There was nearly no adsorption of OCs by TiO 2 NPs, and the physicochemical properties of TiO 2 NPs were largely unaltered by the presence of OCs. However, both OCs and NPs affected the biophysicochemical properties of algal cells and thereby influenced the cell surface binding and/or internalization. TiO 2 NPs significantly increased the bioaccumulation of each OC. However, with the exception of atrazine, the bioaccumulation of TiO 2 NPs decreased when used with each OC. The distinct joint toxicity outcomes were a result of the balance between the increased toxicities of OCs (increased bioaccumulations) and the altered toxicity of TiO 2 NPs (bioaccumulation can either increase or decrease). These results can significantly improve our understanding of the potential environmental risks associated with NPs.

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

Science.gov (United States)

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.

Science.gov (United States)

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.

Origin of the Enhanced Visible-Light Absorption in N-Doped Bulk Anatase TiO 2 from First-Principles Calculations

KAUST Repository

Harb, Moussab

2011-10-06

Extension of the absorption properties of TiO2 photocatalytic materials to the visible part of the solar spectrum is of major importance for energy and cleaning up applications. We carry out a systematic study of the N-doped anatase TiO2 material using spin-polarized density functional theory (DFT) and the range-separated hybrid HSE06 functional. The thermodynamic stability of competitive N-doped TiO2 structural configurations is studied as a function of the oxygen chemical potential and of various chemical doping agents: N2, (N2 + H2), NH3, N2H4. We show that the diamagnetic TiO (2-3x)N2x system corresponding to a separated substitutional N species (with 2-4% N impurities) and formation of one-half concentration of O vacancies (1-2 atom %) is an optimal configuration thermodynamically favored by NH3, N2H4, and (N2 + H2) chemical doping agents presenting a dual nitrating-reducing character. The simulated UV-vis absorption spectra using the perturbation theory (DFPT) approach demonstrates unambiguously that the diamagnetic TiO(2-3x)N2x system exhibits the enhanced optical absorption in N-doped TiO2 under visible-light irradiation. Electronic analysis further reveals a band gap narrowing of 0.6 eV induced by delocalized impurity states located at the top of the valence band of TiO 2. A fruitful comparison with experimental data is furnished. © 2011 American Chemical Society.

The Synthesis of Eu3+ Doped with TiO2 Nano-Powder and Application as a Pesticide Sensor

International Nuclear Information System (INIS)

Yao, Fei; Sun, Yang; Tan, Chunlei; Wei, Song; Zhang, Xiaojuan; Hu, Xiaoyun; Fan, Jun

2011-01-01

Using tetrabutyl titanate as precursor, Eu 3+ doped TiO 2 nano-powder was prepared by sol-gel method, the nature of luminescence of nano-powder was studied. The interaction of chlorpyrifos with Eu 3+ doped TiO 2 was studied by absorption and fluorescence spectroscopy. The results indicated the fluorescence intensity of Eu 3+ doped TiO 2 was quenched by chlorpyrifos and the quenching rate constant (kq) was 1.24Χ10 11 L/mol·s according to the Stern-Volmer equation. The dynamics of photoinduced electron transfer from chlorpyrifos to conduction band of TiO 2 nanoparticle was observed and the mechanism of electron transfer had been confirmed by the calculation of free energy change (ΔG et ) by applying Rehm-Weller equation as well as energy level diagram. A new rapid method for detection of chlorpyrifos was established according to the fluorescence intensity of Eu 3+ doped TiO 2 was proportional to chlorpyrifos concentration. The range of detection was 5.0Χ10 -10 -2.5Χ10 -7 mol/L and the detection limit (3σ) was 3.2Χ10 -11 mol/L

Characterization and mechanism analysis of N doped TiO2 with visible light response and its enhanced visible activity

International Nuclear Information System (INIS)

Cheng Xiuwen; Yu Xiujuan; Xing Zipeng

2012-01-01

Nitrogen doped TiO 2 nanoparticles were synthesized through a hydrolysis-precipitation process using ammonia water as the doping species. The resulting materials were characterized by XRD, DRS, SPS, XPS and FT-IR. Further, the activity enhanced-mechanism was discussed in detail. XRD results showed that doping with nitrogen could effectively retard the phase transformation of TiO 2 from anatase to rutile and increase the anatase crystallinity. DRS and SPS results indicated that the light absorbance edge of nitrogen doped TiO 2 nanoparticle was obviously red-shifted to visible light region and the separation rates of photogenerated charge carriers were greatly improved, respectively. XPS and FT-IR analysis implied that the contents of surface hydroxyl groups were improved significantly and the VBM (valance bond maximum) of O2p was 2.3 eV. Under the visible light irradiation with 120 min, a 65.3% degradation rate of phenol could be achieved. The photocatalytic activity of nitrogen doped TiO 2 was 2.08 and 1.97 times than that of pure TiO 2 and P25 TiO 2 , respectively. The enhanced visible light activity was attributed to the well anatase crystallinity, small crystallite size, intense light absorbance edge in visible region, more content of surface hydroxyl groups and high separation efficiency of photogenerated charge carriers.

Preparation and Characterization of Cu loaded TiO2 Nano tube Arrays and their Photo catalytic Activity

International Nuclear Information System (INIS)

Syazwani Mohd Zaki; Sreekantan, Srimala

2011-01-01

This paper described the preparation of Cu loaded TiO 2 nano tube arrays. Firstly, TiO 2 nano tube arrays were formed by anodization. Afterwards, the formed nano tube arrays were incorporated with Cu by wet impregnation method. The soaking time and concentration were varied to obtain an optimum set of parameter for Cu incorporation in TiO 2 nano tubes. After anodization, all samples were annealed at 400 degree Celsius for 4 hours to obtain anatase phase. The nano tube arrays were characterized by field emission scanning electron microscopy (FESEM), x-ray diffraction (XRD) and x-ray photoelectron spectra (XPS). An average diameter 63.02 nm and length 12.15 μm were obtained for TiO 2 nano tubes. The photo catalytic activity of these nano tubes were investigated with methyl orange (MO) and the TiO 2 nano tube prepared in 0.01 M of Cu (NO 3 ) 2 solution within 3 hours demonstrates the highest photo catalytic activity with 83.6 % degradation of methyl orange. (author)

Structural and electronic properties of Mg and Mg-Nb co-doped TiO2 (101) anatase surface

International Nuclear Information System (INIS)

Sasani, Alireza; Baktash, Ardeshir; Mirabbaszadeh, Kavoos; Khoshnevisan, Bahram

2016-01-01

Highlights: • Formation energy of Mg and Mg-Nb co-doped TiO_2 anatase surface (101) is studied. • Effect of Mg defect to the TiO_2 anatase (101) surface and bond length distribution of the surface is studied and it is shown that Mg defects tend to stay far from each other. • Effect of Mg and Nb to the bond length distribution of the surface studied and it is shown that these defects tend to stay close to each other. • Effects of Mg and Mg-Nb defects on DSSCs using TiO_2 anatase hosting these defects are studied. - Abstract: In this paper, by using density functional theory, Mg and Nb-Mg co-doping of TiO_2 anatase (101) surfaces are studied. By studying the formation energy of the defects and the bond length distribution of the surface, it is shown that Mg defects tend to stay as far as possible to induce least possible lattice distortion while Nb and Mg defects stay close to each other to cause less stress to the surface. By investigating band structure of the surface and changes stemmed from the defects, potential effects of Mg and Mg-Nb co-doping of TiO_2 surface on dye-sensitized solar cells are investigated. In this study, it is shown that the Nb-Mg co-doping could increase J_S_C of the surface while slightly decreasing V_O_C compared to Mg doped surface, which might result in an increase in efficiency of the DSSCs compared to Nb or Mg doped surfaces.

Linear and nonlinear optical studies of bare and copper doped TiO2 nanoparticles via sol gel technique

Science.gov (United States)

Rajamannan, B.; Mugundan, S.; Viruthagiri, G.; Praveen, P.; Shanmugam, N.

2014-01-01

In general, the nanoparticles of TiO2 may exist in the phases of anatase, rutile and brookite. In the present work, we used titanium terta iso propoxide and 2-propanol as a common starting material to prepare the precursors of bare and copper doped nanosized TiO2. Then the synthesized products were calcinated at 500 °C and after calcination the pure TiO2 nanoparticles in anatase phase were harvested. The crystallite sizes of bare and copper doped TiO2 nanoparticles were calculated from X-ray diffraction analysis. The existence of functional groups of the samples was identified by Fourier transform infrared spectroscopy. The optical properties of bare and doped samples were carried out using UV-DRS and photoluminescence measurements. The surface morphology and the element constitution of the copper doped TiO2 nanoparticles were studied by scanning electron microscope fitted with energy dispersive X-ray spectrometer arrangement. The nonlinear optical properties of the products were confirmed by Kurtz second harmonic generation (SHG) test and the output power generated by the nanoparticle was compared with that of potassium di hydrogen phosphate (KDP).

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

Science.gov (United States)

Srivastava, Subodh; Sharma, S. S.; Sharma, Preetam; Sharma, Vinay; Rajura, Rajveer Singh; Singh, M.; Vijay, Y. K.

2014-04-01

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

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.

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.

Safe-by-Design CuO Nanoparticles via Fe-Doping, Cu-O Bond Length Variation, and Biological Assessment in Cells and Zebrafish Embryos.

Science.gov (United States)

Naatz, Hendrik; Lin, Sijie; Li, Ruibin; Jiang, Wen; Ji, Zhaoxia; Chang, Chong Hyun; Köser, Jan; Thöming, Jorg; Xia, Tian; Nel, Andre E; Mädler, Lutz; Pokhrel, Suman

2017-01-24

The safe implementation of nanotechnology requires nanomaterial hazard assessment in accordance with the material physicochemical properties that trigger the injury response at the nano/bio interface. Since CuO nanoparticles (NPs) are widely used industrially and their dissolution properties play a major role in hazard potential, we hypothesized that tighter bonding of Cu to Fe by particle doping could constitute a safer-by-design approach through decreased dissolution. Accordingly, we designed a combinatorial library in which CuO was doped with 1-10% Fe in a flame spray pyrolysis reactor. The morphology and structural properties were determined by XRD, BET, Raman spectroscopy, HRTEM, EFTEM, and EELS, which demonstrated a significant reduction in the apical Cu-O bond length while simultaneously increasing the planar bond length (Jahn-Teller distortion). Hazard screening was performed in tissue culture cell lines and zebrafish embryos to discern the change in the hazardous effects of doped vs nondoped particles. This demonstrated that with increased levels of doping there was a progressive decrease in cytotoxicity in BEAS-2B and THP-1 cells, as well as an incremental decrease in the rate of hatching interference in zebrafish embryos. The dissolution profiles were determined and the surface reactions taking place in Holtfreter's solution were validated using cyclic voltammetry measurements to demonstrate that the Cu + /Cu 2+ and Fe 2+ /Fe 3+ redox species play a major role in the dissolution process of pure and Fe-doped CuO. Altogether, a safe-by-design strategy was implemented for the toxic CuO particles via Fe doping and has been demonstrated for their safe use in the environment.

Facile fabrication of Si-doped TiO2 nanotubes photoanode for enhanced photoelectrochemical hydrogen generation

Science.gov (United States)

Dong, Zhenbiao; Ding, Dongyan; Li, Ting; Ning, Congqin

2018-04-01

Photoelectrochemical (PEC) water splitting based doping modified one dimensional (1D) titanium dioxide (TiO2) nanostructures provide an efficient method for hydrogen generation. Here we first successfully fabricated 1D Si-doped TiO2 (Ti-Si-O) nanotube arrays through anodizing Ti-Si alloys with different Si amount, and reported the PEC properties for water splitting. The Ti-Si-O nanotube arrays fabricated on Ti-5 wt.% Si alloy and annealed at 600 °C possess higher PEC activity, yielding a higher photocurrent density of 0.83 mA/cm2 at 0 V vs. Ag/AgCl. The maximum photoconversion efficiency was 0.54%, which was 2.7 times the photoconversion efficiency of undoped TiO2.

Al2O3 doped TiO2 ceramic waste forms

International Nuclear Information System (INIS)

Uno, Masayoshi; Kinoshita, Hajime; Sakai, Etsuro; Ikeda, Akira; Matsumoto, Y.; Yamanaka, Shinsuke

1999-01-01

Melting of the mixture of Nd 2 O 3 , CeO 2 , SrO, TiO 2 and Al 2 O 3 at 1673 K for 1 hour produced one RE 2 Ti 3 O 9 phase compound. Differential Scanning Calorimetry (DSC) measurement showed that the melting temperature of this compound was 1646 K. Density of the alumina doped oxide was higher than that of the oxide obtained by the pressing and sintering without alumina. Vickers hardness of the oxide obtained by the pressing and sintering was 5.3 GPa and nearly same as that of glass waste. That of the alumina doped oxide was around 7 GPa. 7 days Soxhlet leach test (MCC-5) followed by Inductively Coupled Plasma Spectrometry (ICP) showed that normalized leaching rate of Ti for the oxide obtained by the pressing and sintering was 5.54 x 10 -3 kg/m 2 and that for the alumina doped oxide was 2.24 x 10 -3 kg/m 2 . The value of Sr for the pressed and sintered sample was 0.034 x 10 -3 kg/m 2 but that for alumina doped sample was below the detection limit (0.01 x 10 -3 kg/m 2 ). Al was not detected from the leachate of the alumina doped sample. (author)

Eu"2"+ doped TiO_2 nano structures synthesized by HYSYCVD for thermoluminescence dosimetry

International Nuclear Information System (INIS)

Perez A, J. A.; Leal C, A. L.; Melendrez A, R.; Barboza F, M.

2016-10-01

Titania (TiO_2) has attracted interest owing his potential applications as dosimetry material given his excellent optical, electrical and thermal properties and the ability to shape his structure make TiO_2 suitable for research and dosimetry applications. In this work, a systematic study to know the magnitude of processing parameters influence on thermoluminescent properties of undoped (TiO_2) and doped (TiO_2:Eu"2"+) nano materials obtained by hybrid precursor systems chemical vapor deposition (HYSYCVD) technique is presented. Synthesis of one dimension nano structures of TiO_2:Eu"2"+ was carried out using K_2TiF_6 and EuCl_2 as dopant at 0.5, 1, 2.5 and 5 wt %. The nano structures samples were irradiated with β-ray in a doses range of 0.083-3000 Gy. All thermoluminescence (Tl) glow curves showed 3 broad Tl peaks around 373, 473 and 573 K, and a dosimetric linear behavior from 0.083 to 300 Gy. The Tl has a good reproducibility, with deviations of around 5%, making these TiO_2:Eu"2"+ nano materials suitable for dosimetric applications. (Author)

High-performance and renewable supercapacitors based on TiO2 nanotube array electrodes treated by an electrochemical doping approach

International Nuclear Information System (INIS)

Wu, Hui; Li, Dongdong; Zhu, Xufei; Yang, Chunyan; Liu, Dongfang; Chen, Xiaoyuan; Song, Ye; Lu, Linfeng

2014-01-01

Although one-dimensional anodic TiO 2 nanotube arrays have shown promise as supercapacitor electrode materials, their poor electronic conductivity embarrasses the practical applications. Here, we develop a simple electrochemical doping method to significantly improve the electronic conductivity and the electrochemical performances of TiO 2 nanotube electrodes. These TiO 2 nanotube electrodes treated by the electrochemical hydrogenation doping (TiO 2 -H) exhibit a very high average specific capacitance of 20.08 mF cm −2 at a current density of 0.05 mA cm −2 , ∼20 times more than the pristine TiO 2 nanotube electrodes. The improved electrochemical performances can be attributed to ultrahigh conductivity of TiO 2 -H due to the introduction of interstitial hydrogen ions and oxygen vacancies by the doping. The supercapacitor device assembled by the doped electrodes delivers a specific capacitance of 5.42 mF cm −2 and power density of 27.66 mW cm −2 , on average, at the current density of 0.05 mA cm −2 . The device also shows an outstanding rate capability with 60% specific capacitance retained when the current density increases from 0.05 to 4.00 mA cm −2 . More interestingly, the electrochemical performances of the supercapacitor after cycling can be recovered by the same doping process. This strategy boosts the performances of the supercapacitor, especially cycling stability

Au Nanoparticles Decorated TiO2 Nanotube Arrays as a Recyclable Sensor for Photoenhanced Electrochemical Detection of Bisphenol A.

Science.gov (United States)

Hu, Liangsheng; Fong, Chi-Chun; Zhang, Xuming; Chan, Leo Lai; Lam, Paul K S; Chu, Paul K; Wong, Kwok-Yin; Yang, Mengsu

2016-04-19

A photorefreshable and photoenhanced electrochemical sensing platform for bisphenol A (BPA) detection based on Au nanoparticles (NPs) decorated carbon doped TiO2 nanotube arrays (TiO2/Au NTAs) is described. The TiO2/Au NTAs were prepared by quick annealing of anodized nanotubes in argon, followed by controllable electrodeposition of Au NPs. The decoration of Au NPs not only improved photoelectrochemical behavior but also enhanced electrocatalytic activities of the resulted hybrid NTAs. Meanwhile, the high photocatalytic activity of the NTAs allowed the electrode to be readily renewed without damaging the microstructures and surface states after a short UV treatment. The electrochemical detection of BPA on TiO2/Au NTAs electrode was significantly improved under UV irradiation as the electrode could provide fresh reaction surface continuously and the further increased photocurrent resulting from the improved separation efficiency of the photogenerated electron-hole pairs derived from the consumption of holes by BPA. The results showed that the refreshable TiO2/Au NTAs electrode is a promising sensor for long-term BPA monitoring with the detection limit (S/N = 3) of 6.2 nM and the sensitivity of 2.8 μA·μM(-1)·cm(-2).

The synergistic effect of nitrogen-doped titanium dioxide/mercaptobenzoic acid/silver nanocomplexes for surface-enhanced Raman scattering

Science.gov (United States)

Feng, Jun; Bao, Wenyuan; Li, Lijun; Cheng, Hao; Huang, Wenyi; Kong, Hongxing; Li, Yanqing

2018-03-01

We synthesized titanium dioxide (TiO2) and nitrogen-doped TiO2 nanoparticles (N-TiO2 NPs) via a sol-hydrothermal method using ammonium chloride (NH4Cl) as the nitrogen (N) source. Furthermore, an N-TiO2/4-mercaptobenzoic acid (4-MBA)/silver (Ag) nanocomplex served as an active substrate for surface-enhanced Raman scattering (SERS) and was prepared by self-assembly. During SERS, the Raman signals of 4-MBA of the N-TiO2/MBA/Ag nanocomplexes exhibited higher intensity and sensitivity than pure TiO2/MBA/Ag, with 1% N doping in N-TiO2, producing the strongest Raman signals. We characterized the N-TiO2 hybrid materials by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and ultraviolet-visible diffuse reflectance spectra. N doping did not influence the phase of the TiO2 crystal. The doped N entered into the crystal lattice of the TiO2, replacing some oxygen (O) to form Ti-O-N or Ti-N-O linkage. The results indicated that an appropriate amount of N doping could enhance the SERS performance of the TiO2 SERS substrate via N substitution doping. These doping forms were beneficial to the molecular charge transfer (CT), and this resulted in improved SERS performance for N-doped TiO2 NPs. We attributed this improvement to the formation of N-doping energy levels that were beneficial to the process of TiO2 to MBA molecule CT. This work not only enriched the nonmetal-doped CT mechanism in SERS but also provided several reference values for practical applications. [Figure not available: see fulltext.

Phosphorous-doped TiO2 nanoparticles: synthesis, characterization, and visible photocatalytic evaluation on sulfamethazine degradation.

Science.gov (United States)

Mendiola-Alvarez, Sandra Yadira; Hernández-Ramírez, Ma Aracely; Guzmán-Mar, Jorge Luis; Garza-Tovar, Lorena Leticia; Hinojosa-Reyes, Laura

2018-05-24

Mesoporous phosphorous-doped TiO 2 (TP) with different wt% of P (0.5, 1.0, and 1.5) was synthetized by microwave-assisted sol-gel method. The obtained materials were characterized by XRD with cell parameters refinement approach, Raman, BET-specific surface area analysis, SEM, ICP-OES, UV-Vis with diffuse reflectance, photoluminescence, FTIR, and XPS. The photocatalytic activity under visible light was evaluated on the degradation of sulfamethazine (SMTZ) at pH 8. The characterization of the phosphorous materials (TP) showed that incorporation of P in the lattice of TiO 2 stabilizes the anatase crystalline phase, even increasing the annealing temperature. The mesoporous P-doped materials showed higher surface area and lower average crystallite size, band gap, and particle size; besides, more intense bands attributed to O-H bond were observed by FTIR analysis compared with bare TiO 2 . The P was substitutionally incorporated in the TiO 2 lattice network as P 5+ replacing Ti 4+ to form Ti-O-P bonds and additionally present as PO 4 3-  on the TiO 2 surface. All these characteristics explain the observed superior photocatalytic activity on degradation (100%) and mineralization (32%) of SMTZ under visible radiation by TP catalysts, especially for P-doped TiO 2 1.0 wt% calcined at 450 °C (TP1.0-450). Ammonium, nitrate, and sulfate ions released during the photocatalytic degradation were quantified by ion chromatography; the nitrogen and sulfur mass balance evidenced the partial mineralization of this recalcitrant molecule.

Optical excitations in CuO2-sheets doped and undoped with electrons

International Nuclear Information System (INIS)

Tokura, Y.; Arima, T.; Koshihara, S.; Takagi, H.; Ido, T.; Ishibashi, S.; Uchida, S.

1989-01-01

This paper reports optical reflectance spectra measured on single crystals of parent families of high T c copper oxide compounds with single-layered CuO 2 -sheets, which clearly show the strong transitons across the charge-transfer (CT) gaps at 1.5-2.0 eV in various types of CuO 2 -sheets. The carrier-doping effects on the CT excitations have been investigated on the Sr-doped La 2 CuO 4 and Ce-doped Nd 2 O 4 crystals

Enhanced Visible Light Photocatalytic Activity of V2O5 Cluster Modified N-Doped TiO2 for Degradation of Toluene in Air

Directory of Open Access Journals (Sweden)

Fan Dong

2012-01-01

Full Text Available V2O5 cluster-modified N-doped TiO2 (N-TiO2/V2O5 nanocomposites photocatalyst was prepared by a facile impregnation-calcination method. The effects of V2O5 cluster loading content on visible light photocatalytic activity of the as-prepared samples were investigated for degradation of toluene in air. The results showed that the visible light activity of N-doped TiO2 was significantly enhanced by loading V2O5 clusters. The optimal V2O5 loading content was found to be 0.5 wt.%, reaching a removal ratio of 52.4% and a rate constant of 0.027 min−1, far exceeding that of unmodified N-doped TiO2. The enhanced activity is due to the deposition of V2O5 clusters on the surface of N-doped TiO2. The conduction band (CB potential of V2O5 (0.48 eV is lower than the CB level of N-doped TiO2 (−0.19 V, which favors the photogenerated electron transfer from CB of N-doped TiO2 to V2O5 clusters. This function of V2O5 clusters helps promote the transfer and separation of photogenerated electrons and holes. The present work not only displays a feasible route for the utilization of low cost V2O5 clusters as a substitute for noble metals in enhancing the photocatalysis but also demonstrates a facile method for preparation of highly active composite photocatalyst for large-scale applications.

Defects controlling electrical and optical properties of electrodeposited Bi doped Cu2O

Science.gov (United States)

Brandt, Iuri S.; Tumelero, Milton A.; Martins, Cesar A.; Plá Cid, Cristiani C.; Faccio, Ricardo; Pasa, André A.

2018-04-01

Doping leading to low electrical resistivity in electrodeposited thin films of Cu2O is a straightforward requirement for the construction of efficient electronic and energy devices. Here, Bi (7 at. %) doped Cu2O layers were deposited electrochemically onto Si(100) single-crystal substrates from aqueous solutions containing bismuth nitrate and cupric sulfate. X-ray photoelectron spectroscopy shows that Bi ions in a Cu2O lattice have an oxidation valence of 3+ and glancing angle X-ray diffraction measurements indicated no presence of secondary phases. The reduction in the electrical resistivity from undoped to Bi-doped Cu2O is of 4 and 2 orders of magnitude for electrical measurements at 230 and 300 K, respectively. From variations in the lattice parameter and the refractive index, the electrical resistivity decrease is addressed to an increase in the density of Cu vacancies. Density functional theory (DFT) calculations supported the experimental findings. The DFT results showed that in a 6% Bi doped Cu2O cell, the formation of Cu vacancies is more favorable than in an undoped Cu2O one. Moreover, from DFT data was observed that there is an increase (decrease) of the Cu2O band gap (activation energy) for 6% Bi doping, which is consistent with the experimental results.

Antimicrobial activity and biocompatibility of Ag{sup +}- and Cu{sup 2+}-doped biphasic hydroxyapatite/α-tricalcium phosphate obtained from hydrothermally synthesized Ag{sup +}- and Cu{sup 2+}-doped hydroxyapatite

Energy Technology Data Exchange (ETDEWEB)

Radovanović, Željko, E-mail: zradovanovic@tmf.bg.ac.rs [Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade (Serbia); Jokić, Bojan; Veljović, Djordje; Dimitrijević, Suzana [Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade (Serbia); Kojić, Vesna [Oncology Institute of Vojvodina, Institutski put 4, 21204 Sremska Kamenica (Serbia); Petrović, Rada; Janaćković, Djordje [Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade (Serbia)

2014-07-01

Hydroxyapatite (HAp) powders doped with Ag{sup +} or Cu{sup 2+} were synthesized by a hydrothermal method in order to obtain biomaterial with an antimicrobial effect. The synthesis was performed with two contents of dopant (Ag{sup +} or Cu{sup 2+}) by considering both the antimicrobial activities and biocompatibility of the powders. The doped HAp was annealed at 1200 °C for 2 h with the intention of investigating the influence of doping with Ag{sup +} and Cu{sup 2+} on the creation of the biphasic HAp/α-tricalcium phosphate (HAp/α-TCP) and determining the antimicrobial activity and biocompatibility of the obtained biphasic powders. Analyses of all powders, undoped and doped HAp and HAp/α-TCP, were performed by Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), atomic absorption spectroscopy (AAS) and energy-dispersive X-ray spectroscopy (EDS). The in vitro antibacterial activities of the powders were evaluated against: Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. All powders showed good antimicrobial activity but generally the powders of doped HAp/α-TCP had more uniform results against all pathogenic microorganisms than the powders of doped HAp. In vitro biocompatibility tests, MTT and DET, were used to evaluate the biocompatibility of Ag{sup +}- and Cu{sup 2+}-doped HAp/α-TCP with MRC-5 human fibroblast cells. These tests confirmed that powders do not have a cytotoxic effect. The HAp/α-TCP powders doped with the lower content of Ag{sup +} and Cu{sup 2+} showed especially good biocompatibility. Antimicrobial and biocompatibility tests recommend the Ag{sup +}- and Cu{sup 2+}-doped HAp/α-TCP as promising material for use in reconstructive surgery of bone.

The influence of alizarin and fluorescein on the photoactivity of Ni, Pt and Ru-doped TiO2 layers

International Nuclear Information System (INIS)

Rosu, Marcela-Corina; Suciu, Ramona-Crina; Lazar, Mihaela D.; Bratu, I.

2013-01-01

Highlights: ► The Ni, Pt, Ru-doped TiO 2 materials and sensitized with alizarin and fluorescein dyes were prepared by wet chemical route. ► The samples were characterized by: UV–vis spectroscopy, spectrofluorimetry, FT/IR spectroscopy and microscopy, X-ray diffraction and N 2 physisorption measurements. ► A combined influence of the dopants and dyes was observed, leading to a beneficial effect to TiO 2 photoactivity. -- Abstract: The doping with different metal ions and sensitization with organic compounds are two well known methods used to improve the photoactivity of TiO 2 . In this respect, the metallic ions-doped TiO 2 samples were prepared by embedding Ni, Pt and Ru ions into TiO 2 crystalline network and then, each sample was sensitized with alizarin and fluorescein dyes. The qualitative evaluation of prepared TiO 2 -based materials was made by: UV–vis spectroscopy, spectrofluorimetry, FT/IR spectroscopy and microscopy, X-ray diffraction and N 2 physisorption measurements. The optoelectronic properties investigated by UV–vis spectroscopy show that the optical response of Ni-doped TiO 2 layer shifts to visible. The X-ray spectra do not show peaks of nickel, platinum and ruthenium oxide crystals or pure metals. The FT/IR spectra proved the presence of dye molecules adsorbed on titania nanoparticles surface. These results demonstrated that the studied dopants and dyes have potential to promote modified TiO 2 -based materials as good candidates to be used in photolectrocatalytic processes

Preparation And Characterization of Cu-Fe/ TiO2 Photocatalyst for Visible Light Deep Desulfurization

International Nuclear Information System (INIS)

Hayyiratul Fatimah Mohd Zaid; Kait, C.F.; Mohamed Ibrahim Abdul Mutalib

2016-01-01

A photooxidative system for deep desulfurization of model diesel fuel was explored. Nanoparticles of anatase titania (TiO 2 ) were synthesized via sol-gel hydrothermal method. The TiO 2 was further modified with bimetallic Cu-Fe using wet-impregnation method followed by calcination process in order to extend the activity region of the photocatalyst to visible-light. A series of bimetallic 2.2 wt % Cu-Fe/ TiO 2 photocatalysts with different Cu:Fe mass compositions were characterized for their physical, chemical and optical properties using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), diffuse reflectance UV-visible spectroscopy (DR-UV-Vis), Fourier Transform Infrared Spectroscopy (FTIR) and Brunauer-Emmet-Teller (BET) surface area analysis. The performance of the photocatalysts was evaluated for photooxidation of dibenzothiophene (DBT) as the sulfur species from model oil in the presence of hydrogen peroxide, H 2 O 2 under 500 W visible light illumination. The highest sulfur conversion of 82.36 % was observed for photocatalyst with 10:1Cu:Fe mass composition. (author)

Investigations of spherical Cu NPs in sodium lauryl sulphate with Tb"3"+ ions dispersed in PVA films

International Nuclear Information System (INIS)

Kumar, Brijesh; Kaur, Gagandeep; Rai, S.B.

2016-01-01

Highlights: • Cu NPs were prepared in SDS using 1064 nm laser radiation at fluence 37, 64 and 88 J/cm"2. • Spherical Cu NPs with average diameter varying between 10 and 50 nm atdifferent fluence. • PL of Tb3+ ions in PVA polymer film is maximum with Cu NPS at fluence 37 J/cm"2. • PVA films of Cu NPs displayed a highly temperature-dependent electrical conductivity. • These copper NPs embedded PVA films can be used as novel, low-cost sensor materials. - Abstract: Cu nanoparticles (NPs) have been prepared in SDS solution using 1064 nm laser radiation at different fluence 37 J/cm"2, 64 J/cm"2 and 88 J/cm"2 and structurally characterized. The TEM measurements reveal the presence of nanoparticles of spherical shape with different size. The size of the nanoparticles and their concentration increases with the increase of fluence.The effect of these Cu nanoparticles on the emissive properties of Tb"3"+ ion in polymer films has been studied. It is found that emission intensity of Tb"3"+ first increases and then deceases both with concentration of Cu NPs as well as with sizes. The PL intensity of Tb"3"+ ions is minimum for Cu NPs prepared with highest fluence. It has been explained in term of local field effect. This was also verified by life time measurements. These thin PVA films of copper nanoparticles displayed a highly temperature-dependent electrical conductivity with sensitivity at least comparable to commercial materials which suggest the use of these copper NPs embedded PVA films as novel, low-cost sensor materials.

Facile synthesis and enhanced visible light photocatalytic activity of N and Zr co-doped TiO2 nanostructures from nanotubular titanic acid precursors

Science.gov (United States)

Zhang, Min; Yu, Xinluan; Lu, Dandan; Yang, Jianjun

2013-12-01

Zr/N co-doped TiO2 nanostructures were successfully synthesized using nanotubular titanic acid (NTA) as precursors by a facile wet chemical route and subsequent calcination. These Zr/N-doped TiO2 nanostructures made by NTA precursors show significantly enhanced visible light absorption and much higher photocatalytic performance than the Zr/N-doped P25 TiO2 nanoparticles. Impacts of Zr/N co-doping on the morphologies, optical properties, and photocatalytic activities of the NTA precursor-based TiO2 were thoroughly investigated. The origin of the enhanced visible light photocatalytic activity is discussed in detail.

Degradation of selected industrial dyes using Mg-doped TiO2 polyscales under natural sun light as an alternative driving energy

Science.gov (United States)

Shivaraju, H. P.; Midhun, G.; Anil Kumar, K. M.; Pallavi, S.; Pallavi, N.; Behzad, Shahmoradi

2017-11-01

Designing photocatalytic materials with modified functionalities for the utilization of renewable energy sources as an alternative driving energy has attracted much attention in the area of sustainable wastewater treatment applications. Catalyst-assisted advanced oxidation process is an emerging treatment technology for organic pollutants and toxicants in industrial wastewater. Preparation of visible-light-responsive photocatalyst such as Mg-doped TiO2 polyscales was carried out under mild sol-gel technique. Mg-doped TiO2 polyscales were characterized by powder XRD, SEM, FTIR, and optical and photocatalytic activity techniques. The Mg-doped TiO2 showed a mixed phase of anatase and rutile with an excellent crystallinity, structural elucidations, polyscales morphology, consequent shifting of bandgap energy and adequate photocatalytic activities under visible range of light. Mg-doped TiO2 polyscales were investigated for their efficiencies in the degradation of most commonly used industrial dyes in the real-time textile wastewater. Mg-doped TiO2 polyscales showed excellent photocatalytic degradation efficiency in both model industrial dyes (65-95%) and textile wastewater (92%) under natural sunlight as an alternative and renewable driving energy.

Microglial cells (BV-2) internalize titanium dioxide (TiO2) nanoparticles: toxicity and cellular responses.

Science.gov (United States)

Rihane, Naima; Nury, Thomas; M'rad, Imen; El Mir, Lassaad; Sakly, Mohsen; Amara, Salem; Lizard, Gérard

2016-05-01

Because of their whitening and photocatalytic effects, titanium dioxide nanoparticles (TiO2-NPs) are widely used in daily life. These NPs can be found in paints, plastics, papers, sunscreens, foods, medicines (pills), toothpastes, and cosmetics. However, the biological effect of TiO2-NPs on the human body, especially on the central nervous system, is still unclear. Many studies have demonstrated that the brain is one of the target organs in acute or chronic TiO2-NPs toxicity. The present study aimed to investigate the effect of TiO2-NPs at different concentrations (0.1 to 200 μg/mL) on murine microglial cells (BV-2) to assess their activity on cell growth and viability, as well as their neurotoxicity. Different parameters were measured: cell viability, cell proliferation and DNA content (SubG1 peak), mitochondrial depolarization, overproduction of reactive oxygen species (especially superoxide anions), and ultrastructural changes. Results showed that TiO2-NPs induced some cytotoxic effects with a slight inhibition of cell growth. Thus, at high concentrations, TiO2-NPs were not only able to inhibit cell adhesion but also enhanced cytoplasmic membrane permeability to propidium iodide associated with a loss of mitochondrial transmembrane potential and an overproduction of superoxide anions. No induction of apoptosis based on the presence of a SubG1 peak was detected. The microscopic observations also indicated that small groups of nanosized particles and micron-sized aggregates were engulfed by the BV-2 cells and sequestered as intracytoplasmic aggregates after 24-h exposure to TiO2-NPs. Altogether, our data show that the accumulation TiO2-NPs in microglial BV-2 cells favors mitochondrial dysfunctions and oxidative stress.

Visible light induced electron transfer process over nitrogen doped TiO2 nanocrystals prepared by oxidation of titanium nitride

International Nuclear Information System (INIS)

Wu Zhongbiao; Dong Fan; Zhao Weirong; Guo Sen

2008-01-01

Nitrogen doped TiO 2 nanocrystals with anatase and rutile mixed phases were prepared by incomplete oxidation of titanium nitride at different temperatures. The as-prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), core level X-ray photoelectron spectroscopy (CL XPS), valence band X-ray photoelectron spectroscopy (VB XPS), UV-vis diffuse reflectance spectra (UV-vis DRS), and visible light excited photoluminescence (PL). The photocatalytic activity was evaluated for photocatalytic degradation of toluene in gas phase under visible light irradiation. The visible light absorption and photoactivities of these nitrogen doped TiO 2 nanocrystals can be clearly attributed to the change of the additional electronic (N - ) states above the valence band of TiO 2 modified by N dopant as revealed by the VB XPS and visible light induced PL. A band gap structure model was established to explain the electron transfer process over nitrogen doped TiO 2 nanocrystals under visible light irradiation, which was consistent with the previous theoretical and experimental results. This model can also be applied to understand visible light induced photocatalysis over other nonmetal doped TiO 2

Doping mechanism in pure CuInSe{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Werner, F.; Colombara, D.; Melchiorre, M.; Spindler, C.; Siebentritt, S. [Physics and Materials Science Research Unit, University of Luxembourg, Rue du Brill 41, L-4422 Belvaux (Luxembourg); Valle, N.; El Adib, B. [Materials Research and Technology Department, Luxembourg Institute of Science and Technology, Rue du Brill 41, L-4422 Belvaux (Luxembourg)

2016-05-07

We investigate the dopant concentration and majority carrier mobility in epitaxial CuInSe{sub 2} thin films for different copper-to-indium ratios and selenium excess during growth. We find that all copper-poor samples are n-type, and that hopping conduction in a shallow donor state plays a significant role for carrier transport. Annealing in sodium ambient enhances gallium in-diffusion from the substrate wafer and changes the net doping of the previously n-type samples to p-type. We suggest that sodium incorporation from the glass might be responsible for the observed p-type doping in polycrystalline Cu-poor CuInSe{sub 2} solar cell absorbers.

Solution-processed all-oxide bulk heterojunction solar cells based on CuO nanaorod array and TiO2 nanocrystals

Science.gov (United States)

Wu, Fan; Qiao, Qiquan; Bahrami, Behzad; Chen, Ke; Pathak, Rajesh; Tong, Yanhua; Li, Xiaoyi; Zhang, Tiansheng; Jian, Ronghua

2018-05-01

We present a method to synthesize CuO nanorod array/TiO2 nanocrystals bulk heterojunction (BHJ) on fluorine-tin-oxide (FTO) glass, in which single-crystalline p-type semiconductor of the CuO nanorod array is grown on the FTO glass by hydrothermal reaction and the n-type semiconductor of the TiO2 precursor is filled into the CuO nanorods to form well-organized nano-interpenetrating BHJ after air annealing. The interface charge transfer in CuO nanorod array/TiO2 heterojunction is studied by Kelvin probe force microscopy (KPFM). KPFM results demonstrate that the CuO nanorod array/TiO2 heterojunction can realize the transfer of photo-generated electrons from the CuO nanorod array to TiO2. In this work, a solar cell with the structure FTO/CuO nanoarray/TiO2/Al is successfully fabricated, which exhibits an open-circuit voltage (V oc) of 0.20 V and short-circuit current density (J sc) of 0.026 mA cm‑2 under AM 1.5 illumination. KPFM studies indicate that the very low performance is caused by an undesirable interface charge transfer. The interfacial surface potential (SP) shows that the electron concentration in the CuO nanorod array changes considerably after illumination due to increased photo-generated electrons, but the change in the electron concentration in TiO2 is much less than in CuO, which indicates that the injection efficiency of the photo-generated electrons from CuO to TiO2 is not satisfactory, resulting in an undesirable J sc in the solar cell. The interface photovoltage from the KPFM measurement shows that the low V oc results from the small interfacial SP difference between CuO and TiO2 because the low injected electron concentration cannot raise the Fermi level significantly in TiO2. This conclusion agrees with the measured work function results under illumination. Hence, improvement of the interfacial electron injection is primary for the CuO nanorod array/TiO2 heterojunction solar cells.

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.

Recyclable UV and visible light photocatalytically active amorphous TiO2 doped with M (III) ions (M = Cr and Fe)

International Nuclear Information System (INIS)

Buddee, Supat; Wongnawa, Sumpun; Sirimahachai, Uraiwan; Puetpaibool, Walailak

2011-01-01

Research highlights: → The low photocatalytic activity of amorphous TiO2 was enhanced by doping with Cr(III) or Fe(III) ions. → The doped catalysts performed close to P25 under UV light and better with visible light. → The doped catalysts can be recycled. - Abstract: Samples of amorphous TiO 2 doped with Cr(III) and Fe(III), designated as Cr-TiO 2 and Fe-TiO 2 , were prepared via modified impregnation method. The resulting products were characterized by X-ray diffraction, scanning electron microscopy, specific surface area by the Brunauer, Emmett and Teller method, UV-vis absorption and diffuse reflectance spectroscopy, and electron spin resonance spectroscopy. Experimental results revealed that the concentrations of dopants under studied, from 0.05 to 0.2 mol%, had no effect on the phase of products. The band gap energies shifted from 3.28 eV in the undoped amorphous TiO 2 to 2.50 eV and 2.86 eV for Fe-TiO 2 and Cr-TiO 2 , respectively. The doped amorphous TiO 2 showed photocatalytic activities under both UV and visible light with optimal results at 0.1 mol% dopants. Under UV irradiation, the 0.1 mol% doped samples decolorized methylene blue solutions to the same extent as the commercial TiO 2 samples (P25 and anatase) in 5 h. Under visible light, the doped samples decolorized dye solutions in 12 h while the commercial ones were much less active. The used catalysts can be recycled many times without any special treatment.

SURFACE MODIFICATION OF SEMICONDUCTOR THIN FILM OF TiO2 ON GRAPHITE SUBSTRATE BY Cu-ELECTRODEPOSITION

Directory of Open Access Journals (Sweden)

Fitria Rahmawati

2010-06-01

Full Text Available Surface modification of graphite/TiO2 has been done by mean of Cu electrodeposition. This research aims to study the effect of Cu electrodeposition on photocatalytic enhancing of TiO2. Electrodeposition has been done using CuSO4 0,4 M as the electrolyte at controlled current. The XRD pattern of modified TiO2 thin film on graphite substrate exhibited new peaks at 2θ= 43-44o and 2θ= 50-51o that have been identified as Cu with crystal cubic system, face-centered crystal lattice and crystallite size of 26-30 nm. CTABr still remains in the material as impurities. Meanwhile, based on morphological analysis, Cu particles are dissipated in the pore of thin film. Graphite/TiO2/Cu has higher photoconversion efficiency than graphite/TiO2.   Keywords: semiconductor, graphite/TiO2, Cu electrodeposition

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

OpenAIRE

Sridevi , D.V ,; Ramesh , V; Sakthivel , T; Geetha , K ,; Ratchagar , V ,; Jagannathan , K ,; Rajarajan , K ,; Ramachadran , K ,

2017-01-01

International audience; 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˚C450˚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 functi...

Dopant concentration dependent magnetism of Cu-doped TiO{sub 2} nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Anitha, B.; Khadar, M. Abdul, E-mail: mabdulkhadar@rediffmail.com [University of Kerala, Centre for Nanoscience and Nanotechnology (India)

2016-06-15

Undoped and Cu-doped nanocrystals of TiO{sub 2} having the size range of 8–11 nm were synthesized by peroxide gel method. XRD analysis using Rietveld refinement confirmed anatase phase with a small percentage of rutile content for undoped TiO{sub 2} nanocrystals while a pure anatase phase with preferential growth along [004] direction was observed for nanocrystals of Cu-doped TiO{sub 2}. Variation in the intensity ratios of the XRD peaks of the doped samples compared to that of the undoped sample offered an evidence for the substitutional incorporation of Cu ions in the TiO{sub 2} lattice. The preferential growth of the nanocrystals along the [004] direction was verified using HRTEM analysis. Cu doping extended the optical absorption edge of TiO{sub 2} nanocrystals to the visible spectral region and caused a blue shift and broadening of the E{sub g} (1) Raman active mode of anatase TiO{sub 2}. Undoped TiO{sub 2} sample showed a weak ferromagnetism superimposed on a diamagnetic background while Cu-doped TiO{sub 2} samples exhibited a weak ferromagnetism in the low-field region with a paramagnetic component in the high-field region. The magnetic moment exhibited by the doped samples is interpreted as the resultant of a weak ferromagnetic moment in the low-field region arising from the presence of defects near the surface of TiO{sub 2} nanoparticles or from the interaction of the substituted Cu ions with the oxygen vacancies, and the paramagnetic contribution from the increased Cu dopant concentration near the surface of the particles arising from self-purification mechanism.

Determination of photo-catalytic activity of un-doped and Mn-doped TiO2 anatase powders on acetaldehyde under UV and visible light

International Nuclear Information System (INIS)

Papadimitriou, Vassileios C.; Stefanopoulos, Vassileios G.; Romanias, Manolis N.; Papagiannakopoulos, Panos; Sambani, Kyriaki; Tudose, Valentin; Kiriakidis, George

2011-01-01

Titanium dioxide (TiO 2 ) photocatalytic powder materials doped with various levels of manganese (Mn) were synthesized to be used as additives to wall painting in combating indoor and outdoor air pollution. The heterogeneous photocatalytic degradation of gaseous acetaldehyde (CH 3 CHO) on Mn–TiO 2 surfaces under ultraviolet and visible (UV/Vis) irradiation was investigated, by employing the Photochemical Static Reactor coupled with Fourier-Transformed Infrared spectroscopy (PSR/FTIR) technique. Experiments were performed by exposing acetaldehyde (∼ 400 Pa) and synthetic air mixtures (∼ 1.01 × 10 5 Pa total pressure) on un-doped TiO 2 and doped with various levels of Mn (0.1–33% mole percentage) under UV and visible irradiation at room temperature. Photoactivation was initiated using either UV or visible light sources with known emission spectra. Initially, the photo-activity of CH 3 CHO under the above light sources, and the physical adsorption of CH 3 CHO on Mn–TiO 2 samples in the absence of light were determined prior to the photocatalytic experiments. The photocatalytic loss of CH 3 CHO on un-doped TiO 2 and Mn–TiO 2 samples in the absence and presence of UV or visible irradiation was measured over a long time period (≈ 60 min), to evaluate their relative photocatalytic activity. The gaseous photocatalytic end products were also determined using absorption FTIR spectroscopy. Carbon dioxide (CO 2 ) was identified as the main photocatalysis product. It was found that 0.1% Mn–TiO 2 samples resulted in the highest photocatalytic loss of CH 3 CHO under visible irradiation. This efficiency was drastically diminished at higher levels of Mn doping (1–33%). The CO 2 yields were the highest for 0.1% Mn–TiO 2 samples under UV irradiation, in agreement with the observed highest CH 3 CHO decomposition rates. It was demonstrated that low-level (0.1%) doping of TiO 2 with Mn results in a significant increase of their photocatalytic activity in the visible

Photoinactivation of Escherichia coli by sulfur-doped and nitrogen-fluorine-codoped TiO2 nanoparticles under solar simulated light and visible light irradiation.

Science.gov (United States)

Pathakoti, Kavitha; Morrow, Shavonda; Han, Changseok; Pelaez, Miguel; He, Xiaojia; Dionysiou, Dionysios D; Hwang, Huey-Min

2013-09-03

Titanium dioxide (TiO2) is one of the most widely used photocatalysts for the degradation of organic contaminants in water and air. Visible light (VL) activated sulfur-doped TiO2 (S-TiO2) and nitrogen-fluorine-codoped TiO2 (N-F-TiO2) were synthesized by sol-gel methods and characterized. Their photoinactivation performance was tested against Escherichia coli under solar simulated light (SSL) and VL irradiation with comparison to commercially available TiO2. Undoped Degussa-Evonik P-25 (P-25) and Sigma-TiO2 showed the highest photocatalytic activity toward E. coli inactivation under SSL irradiation, while S-TiO2 showed a moderate toxicity. After VL irradiation, Sigma-TiO2 showed higher photoinactivation, whereas S-TiO2 and P-25 showed moderate toxicity. Oxidative stress to E. coli occurred via formation of hydroxyl radicals leading to lipid peroxidation as the primary mechanism of bacterial inactivation. Various other biological models, including human keratinocytes (HaCaT), zebrafish liver cells (ZFL), and zebrafish embryos were also used to study the toxicity of TiO2 NPs. In conclusion, N-F-TiO2 did not show any toxicity based on the assay results from all the biological models used in this study, whereas S-TiO2 was toxic to zebrafish embryos under all the test conditions. These findings also demonstrate that the tested TiO2 nanoparticles do not show any adverse effects in HaCaT and ZFL cells.

Electrochemical mechanism of eugenol at a Cu doped gold nanoparticles modified glassy carbon electrode and its analytical application in food samples

International Nuclear Information System (INIS)

Lin, Xiaoyun; Ni, Yongnian; Kokot, Serge

2014-01-01

Graphical abstract: A simple one-step electrodeposition method was used to fabricate a Cu doped gold nanoparticles modified glassy carbon electrode. An electrochemical reaction mechanism for o-methoxy phenols was suggested. In addition, the above Cu@AuNPs/GCE was successfully employed for the analysis of eugenol in food samples. - Highlights: • One-step construction of the Cu@AuNPs/GCE electrode. • The modified electrode showed high sensitivity for the analysis of eugenol. • Electrochemical mechanism of eugenol by use of Cu@AuNPs/GCE was inferred. • The novel method was successfully employed for analysis of eugenol in food samples. - Abstract: A simple one-step electrodeposition method was used to construct a glassy carbon electrode (GCE), which has been modified with Cu doped gold nanoparticles (GNPs), i.e. a Cu@AuNPs/GCE. This electrode was characterized with the use of scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The eugenol was electrocatalytically oxidized at the Cu@AuNPs/GCE. At this electrode, in comparison with the behavior at the GCE alone, the corresponding oxidation peak current was enhanced and the shift of the oxidation potentials to lower values was observed. Electrochemical behavior of eugenol at the Cu@AuNPs/GCE was investigated with the use of the cyclic voltammetry (CV) technique, and additionally, in order to confirm the electrochemical reaction mechanism for o-methoxy phenols, CVs for catechol, guaiacol and vanillin were investigated consecutively. Based on this work, an electrochemical reaction mechanism for o-methoxy phenols was suggested, and in addition, the above Cu@AuNPs/GCE was successfully employed for the analysis of eugenol in food samples

Effect of In-Doping on Electronic Structure and Optical Properties of Sr2TiO4

International Nuclear Information System (INIS)

Jiang-Ni, Yun; Zhi-Yong, Zhang; Jun-Feng, Yan; Fu-Chun, Zhang

2009-01-01

The effect of In doping on the electronic structure and optical properties of Sr 2 TiO 4 is investigated by a first-principles calculation of plane wave ultrasoft pseudopotentials based on density functional theory. The calculated results reveal that corner-shared TiO 6 octahedra dominate the main electronic properties of Sr 2 TiO 4 and the covalency of the Ti–O(1) bond in the ab plane is stronger than that of the Ti–O(2) bond along the c-axis. After In doping, there is a little lattice expansion in Sr 2 In 0.125 Ti 0.875 O 4 , and the interaction between the Ti–O bond near the impurity In atom is weakened. The binding energies of Sr 2 TiO 4 and Sr 2 In 0.125 Ti 0.875 O 4 , estimated from the electronic structure calculations indicate that the crystal structure of Sr 2 In 0.125 Ti 0.875 O 4 is still stable after doping, but its stability is lower than that of undoped Sr 2 TiO 4 . Moreover, the valence bands (VBs) of the Sr 2 In 0.125 Ti 0.875 O 4 , system consist of O 2p and In 4d states, and the mixing of O 2p and In 4d states makes the top VBs shift significantly to high energies, resulting in visible light absorption. The adsorption of visible light is of practical importance for the application of Sr 2 TiO 4 as a photocatalyst. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Improved optical response and photocatalysis for N-doped titanium oxide (TiO2) films prepared by oxidation of TiN

International Nuclear Information System (INIS)

Wan, L.; Li, J.F.; Feng, J.Y.; Sun, W.; Mao, Z.Q.

2007-01-01

In order to improve the photocatalytic activity, N-doped titanium oxide (TiO 2 ) films were obtained by thermal oxidation of TiN films, which were prepared on Ti substrates by ion beam assisted deposition (IBAD). The dominating rutile TiO 2 phase was found in films after thermal oxidation. According to the results of X-ray photoelectron spectroscopy (XPS), the residual N atoms occupied O-atom sites in TiO 2 lattice to form Ti-O-N bonds. UV-vis spectra revealed the N-doped TiO 2 film had a red shift of absorption edge. The maximum red shift was assigned to the sample annealed at 750 deg. C, with an onset wavelength at 600 nm. The onset wavelength corresponded to the photon energy of 2.05 eV, which was nearly 1.0 eV below the band gap of pure rutile TiO 2 . The effect of nitrogen was responsible for the enhancement of photoactivity of N-doped TiO 2 films in the range of visible light

Three-dimensional ruthenium-doped TiO ₂ sea urchins for enhanced visible-light-responsive H ₂ production

Energy Technology Data Exchange (ETDEWEB)

Nguyen-Phan, Thuy-Duong; Luo, Si; Vovchok, Dimitriy; Llorca, Jordi; Sallis, Shawn; Kattel, Shyam; Xu, Wenqian; Piper, Louis F. J.; Polyansky, Dmitry E.; Senanayake, Sanjaya D.; Stacchiola, Dario J.; Rodriguez, José A.

2016-01-01

Three-dimensional (3D) monodispersed sea urchin-like Ru-doped rutile TiO2 hierarchical architectures composed of radially aligned, densely-packed TiO2 nanorods have been successfully synthesized via an acid-hydrothermal method at low temperature without the assistance of any structure-directing agent and post annealing treatment. The addition of a minuscule concentration of ruthenium dopants remarkably catalyze the formation of the 3D urchin structure and drive the enhanced photocatalytic H2 production under visible light irradiation, not possible on undoped and bulk rutile TiO2. Increasing ruthenium doping dosage not only increases the surface area up to 166 m2 g-1 but also induces enhanced photo response in the regime of visible and near infrared light. The doping introduces defect impurity levels, i.e. oxygen vacancy and under-coordinated Ti3+, significantly below the conduction band of TiO2, and ruthenium species act as electron donors/acceptors that accelerate the photogenetated hole and electron transfer and efficiently suppress the rapid charge recombination, therefore improving the visible-light-driven activity.

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.

Synthesis and photocatalytic activity of Ce-doped TiO2 and TiO2 nanotubes

International Nuclear Information System (INIS)

Arruda, L.B.; Pereira, E.A.; Paula, F.R.; Lisboa Filho, P.N.

2016-01-01

Full text: One-dimensional nanostructures have been intensively studied, from the point of view of their synthesis and mechanisms of formation, as well as their applications in photonics, solar energy conversion, environmental and photocatalysis, since their properties due high surface area, electrical conductivity and light dispersion effects. Titanium dioxide (TiO2) nanoparticles have been demonstrated to be an effective multifunctional material especially when the particle size is less than 50 nm exhibit photoinduced activities that originate from the semiconductor band gap. TiO2 is semiconductor more used in photocatalysis, for this reason various properties have been thoroughly investigated in order to show that the photocatalytic activity and TiO2 reaction mechanism are influenced by structure, defects and impurities, surface morphology. and interfaces in addition to the concentration of dopants, such as rare-earth elements. Cerium ions, for example, vary between Ce4+ and Ce3 + oxidation state making the cerium oxide appear as CeO2 and Ce2O3 under oxidation and reduction conditions. These different electronic structures of Ce3+ (4f15d0) and Ce4+ (4f05d0) provide different catalytic and optical properties at the TiO2. In this work, samples of Ce-doped TiO2 and TiO2 were synthesized by alkali route, and its photocatalytic activity analyzed in order to create a relationship between the response obtained and the structure and morphology of each sample. Alkali route consists in submitting TiO2 (anatase) powder directly in medium of the NaOH (10M) and maintained at 120°C/20 hours by a glycerin bath with subsequent washed with water and HCl (0.1M) until reaching the desired pH. The synthesized samples were then studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The photocatalytic decomposition of rhodamine B (Rh.B) it was performed under UV irradiation and visible light in air. For the obtained

Synthesis and photocatalytic activity of Ce-doped TiO2 and TiO2 nanotubes

Energy Technology Data Exchange (ETDEWEB)

Arruda, L.B.; Pereira, E.A.; Paula, F.R.; Lisboa Filho, P.N. [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), SP (Brazil)

2016-07-01

Full text: One-dimensional nanostructures have been intensively studied, from the point of view of their synthesis and mechanisms of formation, as well as their applications in photonics, solar energy conversion, environmental and photocatalysis, since their properties due high surface area, electrical conductivity and light dispersion effects. Titanium dioxide (TiO2) nanoparticles have been demonstrated to be an effective multifunctional material especially when the particle size is less than 50 nm exhibit photoinduced activities that originate from the semiconductor band gap. TiO2 is semiconductor more used in photocatalysis, for this reason various properties have been thoroughly investigated in order to show that the photocatalytic activity and TiO2 reaction mechanism are influenced by structure, defects and impurities, surface morphology. and interfaces in addition to the concentration of dopants, such as rare-earth elements. Cerium ions, for example, vary between Ce4+ and Ce3 + oxidation state making the cerium oxide appear as CeO2 and Ce2O3 under oxidation and reduction conditions. These different electronic structures of Ce3+ (4f15d0) and Ce4+ (4f05d0) provide different catalytic and optical properties at the TiO2. In this work, samples of Ce-doped TiO2 and TiO2 were synthesized by alkali route, and its photocatalytic activity analyzed in order to create a relationship between the response obtained and the structure and morphology of each sample. Alkali route consists in submitting TiO2 (anatase) powder directly in medium of the NaOH (10M) and maintained at 120°C/20 hours by a glycerin bath with subsequent washed with water and HCl (0.1M) until reaching the desired pH. The synthesized samples were then studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The photocatalytic decomposition of rhodamine B (Rh.B) it was performed under UV irradiation and visible light in air. For the obtained

Assessment of copper nanoparticles (Cu-NPs) and copper (II) oxide (CuO) induced hemato- and hepatotoxicity in Cyprinus carpio

Science.gov (United States)

Noureen, Aasma; Jabeen, Farhat; Tabish, Tanveer A.; Yaqub, Sajid; Ali, Muhammad; Shakoor Chaudhry, Abdul

2018-04-01

Recently, Cu-based nanoparticles have drawn considerable attention for their various fascinating roles in multiple biological systems. It is recognized that their frequent use can create compatibility challenges for the recipient systems. Nevertheless, it is unclear how various biological interactions affect the compatibility of Cu oxide II (CuO) and Cu oxide nanoparticles (Cu-NPs) for different organisms. Consequently, it has been difficult to perform structured risk assessments for their use in biological systems. Therefore, this study compared the effects of different doses of waterborne Cu-NPs and CuO on the blood and liver of selected groups of Cyprinus (C) carpio. These fish while housed in suitable water tanks were exposed to one of the following treatments for 14 d: control (no added Cu) or 0.5 or 1 or 1.5 mg Cu as Cu-NPs or CuO l-1 of water. We found significant changes in all assessed blood parameters of fish in response to increasing doses from 0 to 1.5 mg of Cu-NPs or CuO. Similarly, increased levels of lipid peroxide and reduced glutathione (GSH) were also observed in the livers of C. carpio in Cu-NPs or CuO treated groups. Enhanced levels of lipid peroxidation and GSH were also recorded in the Cu-NP treated groups compared with the CuO treated groups in a dose dependent manner. The lowest catalase activity was observed in the liver of C. carpio treated with the higer dose of Cu-NPs. Cu-NP or CuO exposure induced significant histological alterations in the liver of C. carpio including focal necrosis, cloudy swelling of hepatocytes, degenerative hepatocytes, vacuolization, pyknotic nuclei, damaged central vein, nuclear hypertrophy, dilated sinusoid, vacuolated degeneration, congestion, and complete degeneration in a dose dependent manner. Substantial alterations in blood and liver specimens were observed in the Cu-NP treated fish when compared with the CuO treated fish. It appeared that the Cu-NPs were more toxic than the CuO as shown by the hemato- and

Photocatalytic behaviors and structural characterization of nanocrystalline Fe-doped TiO2 synthesized by mechanical alloying

International Nuclear Information System (INIS)

Kim, Dong Hyun; Hong, Hyun Seon; Kim, Sun Jae; Song, Jae Sung; Lee, Kyung Sub

2004-01-01

Nanocrystalline Fe-doped TiO 2 powders were synthesized by mechanical alloying (MA) with varying Fe contents from 0 up to 4.8 wt.% to shift the absorption threshold into the visible light region. The photocatalytic feasibility of the Fe-doped TiO 2 powder was evaluated by quantifying the visible light absorption capacity using ultraviolet and visible (UV-Vis) spectroscopy and photoluminescence spectroscopy. Effects of Fe additions on the crystal structures and the morphologies of the Fe-doped powders were also investigated as a function of the doping content using transmission electron microscopy-electron diffraction pattern (TEM-EDP), X-ray diffraction (XRD) and energy dispersive X-ray (EDAX) and X-ray photoelectron spectroscopy (XPS). The UV-Vis study showed that the UV absorption for the Fe-doped powder moved to a longer wavelength (red shift) and the photoefficiency was enhanced. Based on the analysis of the photoluminescence spectra, the red shift was believed to be induced by localizing the dopant level near the valence band of TiO 2 . The UV-Vis absorption depended on the Fe concentration. TEM-EDP and XRD investigations showed that the Fe-doped powder had a rutile phase in which the added Fe atoms were dissolved. The rutile phase was composed of spherical particles and chestnut bur shaped particles, resulting in a larger surface area than the spherical P-25 powder

Pr3+ doped biphasic TiO2 (rutile-brookite) nanorod arrays grown on activated carbon fibers: Hydrothermal synthesis and photocatalytic properties

Science.gov (United States)

Li, Min; Zhang, Xiaomei; Liu, Ying; Yang, Yi

2018-05-01

Praseodymium-doped biphasic TiO2 (rutile-brookite) nanorod arrays (Pr-TiO2 NRAs) were successfully prepared via a two-step hydrothermal reaction on activated carbon fibers (ACFs) which pre-coated with TiO2 nanoparticles at first step. The bicrystalline arrays grown on ACFs are primarily constructed by the well-aligned TiO2 nanorods growing along [0 0 1] direction, which were indicated by the results of SEM and XRD. The nanorods are uniform in diameter and length with about 250 nm and 2.5 μm. The composite photocatalyst with high specific surface area and well-aligned nanostructure are beneficial to enhance the adsorption capacity and even help to suppress electron-hole recombination effectively, which consequently revealed much better (2 times) catalytic performance than that of commercially available P25 TiO2 on methylene blue(MB) photodegradation. In addition, the existence of praseodymium in TiO2 gives rise to shift of absorption edge towards long wavelength, which was indicated by the results of UV-vis DRS. Photodegradation results reveal that Pr-doping significantly improves the activity of TiO2, which was 20% higher than that of undoped TiO2 NRAs for the photodegradation of MB in aqueous medium under visible light irradiation. Meanwhile, the doped amount of Pr had a tiny influence on the photocatalytic performance of the composites. In our experiment, 3% Pr-doped molar concentration was proven to be the relatively optimal dopant concentration for the doping of TiO2 NRAs. Moreover, the photocatalyst grown on ACFs substrates is favorable to reuse and photodegradation rate kept on 76% even after 4 times of reuse.

Efficient solar light-driven degradation of Congo red with novel Cu-loaded Fe3O4@TiO2 nanoparticles.

Science.gov (United States)

Arora, Priya; Fermah, Alisha; Rajput, Jaspreet Kaur; Singh, Harminder; Badhan, Jigyasa

2017-08-01

In this work, Cu-loaded Fe 3 O 4 @TiO 2 core shell nanoparticles were prepared in a single pot by coating of TiO 2 on Fe 3 O 4 nanoparticles followed by Cu loading. X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), thermogravimetric analysis (TGA), Brunauer-Emmett- Teller (BET), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS), and valence band X-ray photoelectron spectroscopy (VB XPS) techniques were used for characterization of as prepared nanoparticles. Synergism between copper and titania was evaluated by studying the solar light-driven photodegradation of Congo red dye solution in the presence of Fe 3 O 4 @TiO 2 nanoparticles on one side and Cu-loaded Fe 3 O 4 @TiO 2 nanoparticles on the other side. The latter performed better than the former catalyst, indicating the enhanced activity of copper-loaded catalyst. Further photodegradation was studied by three means, i.e., under ultraviolet (UV), refluxing, and solar radiations. Cu-loaded Fe 3 O 4 @TiO 2 enhanced the degradation efficiency of Congo red dye. Thus, Cu act possibly by reducing the band gap of TiO 2 and widening the optical response of semiconductor, as a result of which solar light could be used to carry out photocatalysis. Graphical abstract Photodegradation of congo red over Cu-loaded Fe 3 O 4 @TiO 2 nanoparticles.

Theoretical explanation of EPR parameters for Cu2+ ion in TiO2 crystal

International Nuclear Information System (INIS)

Dong, H.N.; Wu, S.Y.; Li, P.

2004-01-01

The EPR parameters anisotropic g-factors g x , g y and g z for Cu 2+ ion and hyperfine structure constants A x , A y and A z for 63 Cu 2+ and 65 Cu 2+ isotopes in rutile (TiO 2 ) crystal are calculated by the method of diagonalizing the full Hamiltonian matrix. The crystal-field parameters contact with the crystal structure by the aid of the superposition model. The calculated results are in reasonable agreement with the observed values. The results are discussed. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Preparation and Characterization of Mn/N Co-Doped TiO2 Loaded on Wood-Based Activated Carbon Fiber and Its Visible Light Photodegradation

Directory of Open Access Journals (Sweden)

Xiaojun Ma

2015-09-01

Full Text Available Using MnSO4·H2O as manganese source and urea as nitrogen source, Mn/N co-doped TiO2 loaded on wood-based activated carbon fiber (Mn/Ti-N-WACF was prepared by sol–gel method. Mn/Ti-N-WACF with different Mn doping contents was characterized by scanning electron microscopy, X-ray diffraction (XRD and X-ray photoelectron spectroscopies (XPS, and ultraviolet-visible spectrophotometer. Results showed that the loading rate of TiO2 in Mn/Ti-N-WACF was improved by Mn/N co-doping. After calcination at 450 °C, the degree of crystallinity of TiO2 was reduced due to Mn/N co-doption in the resulting Mn/Ti-N-WACF samples, but the TiO2 crystal phase was not changed. XPS spectra revealed that some Ti4+ ions from the TiO2 lattice of Mn/Ti-N-WACF system were substituted by doped Mn. Moreover, new bonds formed within N–Ti–N and Ti–N–O because of the doped N that substituted some oxygen atoms in the TiO2 lattice. Notably, the degradation rate of methylene blue for Mn/Ti-N-WACF was improved because of the co-doped Mn/N under visible-light irradiation.

Microcystin-LR removal from aqueous solutions using a magnetically separable N-doped TiO2 nanocomposite under visible light irradiation

Science.gov (United States)

The performance of magnetically separable N-doped TiO2 was found to be significantly improved when compared with a non-magnetic N-doped TiO2 for the aqueous removal of cyanotoxin Microcystin-LR. The observed enhanced photocatalytic activity may be related to the presence of ferri...

A first principle simulation of competitive adsorption of SF6 decomposition components on nitrogen-doped anatase TiO2 (101) surface

Science.gov (United States)

Dong, Xingchen; Zhang, Xiaoxing; Cui, Hao; Zhang, Jun

2017-11-01

Gas insulated switchgear has been widely used in modern electric systems due to its significantly excellent performances such as compact structure and low land occupation as well as the security stability. However, inside defects caused during manufacture process can lead to partial discharge which might develop into serious insulation failure. Online monitoring method on basis of gas sensors is considered a promising way of detecting partial discharge for alarm ahead of time. Research has found that TiO2 nanotubes sensors show good response to SO2, SOF2, SO2F2, the decomposition components as a result of partial discharge. In order to investigate the gas-sensing mechanism of nitrogen-doped TiO2 prepared via plasma treatment methods to SO2, SOF2, and SO2F2, the adsorption structures of both three gas molecules and anatase TiO2 (101) surface were built, and DFT calculations were then carried out for calculation and analysis of adsorption parameters. Adsorption property comparison of anatase TiO2 (101) surface after nitrogen doping with Au doping and without doping shows that nitrogen doping can obviously enhance the adsorption energy for SO2 and SOF2 adsorption and no charge transfer for SO2F2 adsorption, further explaining the adsorption mechanism and doping influence of different doping elements.

Solvothermal syntheses of Bi and Zn co-doped TiO_2 with enhanced electron-hole separation and efficient photodegradation of gaseous toluene under visible-light

International Nuclear Information System (INIS)

Li, Juan-Juan; Cai, Song-Cai; Xu, Zhen; Chen, Xi; Chen, Jin; Jia, Hong-Peng; Chen, Jing

2017-01-01

Highlights: • Bi-Zn co-doped TiO_2 catalysts were prepared by solvothermal route. • The incorporation of Bi doping into the TiO_2 generates intermediate energy levels. • Bi and Zn doping showed the enhanced absorption in visible-light region. • Zn dopant acts as a mediator of interfacial charge transfer. • TiBi_1_._9_%Zn_1_%O_2 exhibited high photocatalytic degradation for toluene. - Abstract: This study investigated the effects of Bi doped and Bi-Zn co-doped TiO_2 on photodegradation of gaseous toluene. The doped TiO_2 with various concentration of metal was prepared using the solvothermal route and characterized by SEM, XRD, Raman, BET, DRS, XPS, PL and EPR. Their photocatalytic activities under visible-light irradiation were drastically influenced by the dopant content. The results showed that moderate metal doping levels were obviously beneficial for the toluene degradation, while high doping levels suppressed the photocatalytic activity. The photocatalytic degradation of toluene over TiBi_1_._9_%O_2 and TiBi_1_._9_%Zn_1_%O_2 can reach to 51% and 93%, respectively, which are much higher than 25% of TiO_2. Bi doping into TiO_2 lattice generates new intermediate energy level of Bi below the CB edge of TiO_2. The electron excitation from the VB to Bi orbitals results in the decreased band gap, extended absorption of visible-light and thus enhances its photocatalytic efficiency. Zn doping not only further enhances the absorption in this visible-light region, but also Zn dopant exists as the form of ZnO crystallites located on the interfaces of TiO_2 agglomerates and acts as a mediator of interfacial charge transfer to suppress the electron-hole recombination. These synergistic effects are responsible for the enhanced photocatalytic performance.

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)

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.

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

Fabrication of predominantly Mn4+ -doped TiO2 nanoparticles under equilibrium conditions and their application as visible-light photocatalyts.

Science.gov (United States)

Wang, Lijie; Fan, Jiajie; Cao, Zetan; Zheng, Yichao; Yao, Zhiqiang; Shao, Guosheng; Hu, Junhua

2014-07-01

The chemical state of a transition-metal dopant in TiO(2) can intrinsically determine the performance of the doped material in applications such as photocatalysis and photovoltaics. In this study, manganese-doped TiO2 is fabricated by a near-equilibrium process, in which the TiO(2) precursor powder precipitates from a hydrothermally obtained transparent mother solution. The doping level and subsequent thermal treatment influence the morphology and crystallization of the TiO(2) samples. FTIR spectroscopy and X-ray photoelectron spectroscopy analyses indicate that the manganese dopant is substitutionally incorporated by replacing Ti(4+) cations. The absorption band edge can be gradually shifted to 1.8 eV by increasing the nominal manganese content to 10 at %. Manganese atoms doped into the titanium lattice are associated with the dominant 4+ valence oxidation state, which introduces two curved, intermediate bands within the band gap and results in a significant enhancement in photoabsorption and the quantity of photogenerated hydroxyl radicals. Additionally, the high photocatalytic performance of manganese-doped TiO(2) is also attributed to the low oxygen content, owing to the equilibrium fabrication conditions. This work provides an important strategy to control the chemical and defect states of dopants by using an equilibrium fabrication process. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A theoretical investigation of the interaction of Immucillin-A with N-doped TiO2 anatase nanoparticles: Applications to nanobiosensors and nanocarriers

Directory of Open Access Journals (Sweden)

Amirali Abbasi

2017-02-01

Full Text Available Objective(s: Adsorption of IMMUCILLIN-A (BCX4430 molecule on the pristine and N-doped TiO2 anatase nanoparticles were studied using the density functional theory (DFT calculations. The adsorption energy analysis indicated that TiO2+IMMUCILLIN-A complexes including OC-substituted TiO2 have higher adsorption energy than the complexes with OT substituted TiO2, thus providing more stable configurations. Methods: The structural properties including bond lengths, adsorption energies and bond angles were analysed. The electronic structure of the adsorption system were investigated in view of the density of states, molecular orbitals and Mulliken charge analysis.Results: The results show that, the interaction of IMMUCILLIN-A drug with N-doped TiO2 nanoparticles is more energetically favorable than the interaction with the pristine ones, suggesting that the N-doped nanoparticles can react with IMMUCILLIN-A drug more efficiently. The Mulliken charge analysis also suggests a charge transfer from IMMUCILLIN-A molecule to the TiO2 nanoparticle.Conclusions: Based on obtained results, it can be concluded that the N-doped TiO2 nanoparticle could be utilized as an efficient candidate for application as highly sensitive nanobiosensors and efficient nanocarriers for IMMUCILLIN-A drugs.

Significant enhancement in the photocatalytic activity of N, W co-doped TiO2 nanomaterials for promising environmental applications

International Nuclear Information System (INIS)

Thind, Sapanbir S; Wu Guosheng; Tian Min; Chen Aicheng

2012-01-01

In this work, a mesoporous N, W co-doped TiO 2 photocatalyst was synthesized via a one-step solution combustion method, which utilized urea as the nitrogen source and sodium tungstate as the tungsten source. The photocatalytic activity of the N, W co-doped TiO 2 photocatalyst was significantly enhanced by a facile UV pretreatment approach and was evaluated by measuring the rate of photodegradation of Rhodamine B under both UV and visible (λ > 420) light. Following the UV pretreatment, the UV photocatalytic activity of the N, W co-doped TiO 2 was doubled. In terms of visible light activity, the UV pretreatment resulted in an extraordinary >12 fold improvement. In order to gain insight into this substantial enhancement, the N, W co-doped TiO 2 photocatalysts were studied using x-ray diffraction, transmission electron microscopy, N 2 physisorption, UV–vis absorbance spectroscopy and x-ray photoelectron spectroscopy prior to and following the UV pretreatment. Our experimental results have revealed that this significant augmentation of photocatalytic activity may be attributed to several synergetic factors, including increase of the specific surface area, reduction of the band gap energy and the removal of carbon impurities. (paper)

Genotoxic and cytotoxic activity of green synthesized TiO2 nanoparticles

Science.gov (United States)

Koca, Fatih Doğan; Duman, Fatih

2018-03-01

Nowadays, nanomaterials that are smaller than 100 nm in size are very attractive owing to their enhanced physicochemical properties. Although they have been used widely for industrial applications, their toxicity still remains a problem. This article is a new record of the synthesis of titanium dioxide nanoparticles (TiO2 NPs) by a Mentha aquatica leaf extract and determination of its toxicity to rat marrow mesenchymal stem cells. In this study, we aimed to determine the genotoxic and cytotoxic effects of biologically synthetized TiO2 NPs. The characteristic peak of the nanomaterial was observed at 354 nm. The mean size of the nanomaterial was measured to be 69 nm from SEM images. According to zeta analysis, the surface charge of the nanomaterial was - 37.6 mV. The crystalline structure of the nanomaterial was determined using XRD analysis. It was concluded that the obtained nanomaterial was TiO2 The results of the FT-IR analysis showed that the functional groups that were found in the plant extract could play an important role in the formation and stabilization of TiO2 NPs. The effective size of the TiO2 NPs was found to be 304 nm using DLS analysis. The TGA analysis results showed that the total mass loss was 4% at 900 °C. According to DNA cleavage analysis results, TiO2 NPs cause damage to the plasmid pBR322 DNA in a concentration-dependant matter. It has been noted that TiO2 NPs lead to decreased cell viability during increased time and concentration of applications on rat marrow mesenchymal stem cells. It has also been determined that bulk TiO2 causes a greater reduction in the stem cell viability compared to the biosynthesized NPs. The obtained results could be useful for further application and toxicity studies.

Photoelectrochemical oxidation of ibuprofen via Cu{sub 2}O-doped TiO{sub 2} nanotube arrays

Energy Technology Data Exchange (ETDEWEB)

Sun, Qiannan [College of Environment and Energy, South China University of Technology, Guangzhou (China); Peng, Yen-Ping, E-mail: yppeng@thu.edu.tw [Department of Environmental Science and Engineering, Tunghai University, Taichung, Taiwan (China); Chen, Hanlin [College of Environment and Energy, South China University of Technology, Guangzhou (China); Chang, Ken-Lin [School of Environmental Science and Engineering and Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou, 51006 China (China); Qiu, Yang-Neng; Lai, Shiau-Wu [Department of Environmental Science and Engineering, Tunghai University, Taichung, Taiwan (China)

2016-12-05

Highlights: • A p–n junction material was synthesized to enhance photocatalytic ability. • Cu{sub 2}O-doped TiO{sub 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{sub 2}O-doped TiO{sub 2} nanotube arrays (Cu{sub 2}O-TNAs) were synthesized and used as a working anode in a photoelectrochemical (PEC) system. The results revealed that the Cu{sub 2}O-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{sub 2}O-TNAs was greatly reduced. SEM images revealed that the supported TiO{sub 2} nanotubes had diameters of approximately 80 nm and lengths of about 2.63 μm. Upon doping with Cu{sub 2}O, the TiO{sub 2} nanotubes maintained their structural integrity, exhibiting no significant morphological change, favoring PEC applications. Under illumination, the photocurrent from Cu{sub 2}O/TNAs was 2.4 times larger than that from TNAs, implying that doping with Cu{sub 2}O 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{sub el}, of TNAs and Cu{sub 2}O/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.

Electrodeposition of flake-like Cu_2O on vertically aligned two-dimensional TiO_2 nanosheet array films for enhanced photoelectrochemical properties

International Nuclear Information System (INIS)

Yang, Lei; Zhang, Miao; Zhu, Kerong; Lv, Jianguo; He, Gang; Sun, Zhaoqi

2017-01-01

Highlights: • Flake-like Cu_2O/TNS with exposed {001} facets constructed p-n heterostructure. • The TNS arrays were used as starting substrates for Cu_2O growth. • The Cu_2O/TNS prepared at −0.4 V exhibits the best photoelectrochemical property. - Abstract: A novel Cu_2O/TNS composite structure of single crystal TiO_2 nanosheet (TNS) arrays decorated with flake-like Cu_2O were synthesized by a facile hydrothermal reaction followed by the electrodeposition process. The effects of deposition potential on the microstructure, morphology, and optical property of the thin films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–vis spectrophotometer. When the deposition potential is higher than −0.4 V, peaks corresponding to Cu appear, meanwhile, flake-like Cu_2O become agglomerating, and transform into dense Cu_2O particles. Additionally, photoelectrochemical experiments indicate that the films deposited at −0.4 V show the lowest resistivity and highest exciton separation efficiency. This enhanced photoelectrochemical properties can be explained by synergistic effect of p-type flake-like Cu_2O and n-type TiO_2 heterojunctions combined with two-dimensional TiO_2 nanosheet with exposed highly reactive {001} facets.