Effect of SiN_x diffusion barrier thickness on the structural properties and photocatalytic activity of TiO₂ films obtained by sol–gel dip coating and reactive magnetron sputtering

• Mohamed Nawfal Ghazzal,
• Eric Aubry,
• Nouari Chaoui and
• Didier Robert

Beilstein J. Nanotechnol. 2015, 6, 2039–2045, doi:10.3762/bjnano.6.207

• films obtained by each process was discussed. Keywords: diffusion barrier; photocatalysis; reactive sputtering; SiNx; sol–gel; titanium dioxide film; TiO2; Introduction Titanium dioxide thin films in active phase (mostly anatase) have been widely studied due to their ability to produce strong oxidant

• required in order to obtain the photoactive anatase phase. However, Na+ ions have a detrimental effect on the photocatalytic efficiency of TiO2 [3][4][7]. The poisoning effect of the Na+ ions on the photocatalytic activity occurs in different ways and depends on their concentration, for example: (a) Na

• + ions increase the temperature of anatase formation and increase the particle size [4][7], (b) Na+ ions inhibit the formation of the anatase phase and act as a recombination center of photo-generated electron–hole pairs [3], and (c) Na+ ions induce the formation of brookite or sodium titanate (Na2OxTiO2

Nanostructuring of GeTiO amorphous films by pulsed laser irradiation

• Valentin S. Teodorescu,
• Cornel Ghica,
• Adrian V. Maraloiu,
• Mihai Vlaicu,
• Andrei Kuncser,
• Magdalena L. Ciurea,
• Ionel Stavarache,
• Ana M. Lepadatu,
• Nicu D. Scarisoreanu,
• Andreea Andrei,
• Valentin Ion and
• Maria Dinescu

Beilstein J. Nanotechnol. 2015, 6, 893–900, doi:10.3762/bjnano.6.92

• matrix was also evidenced in amorphous GeTiO films annealed in a conventional furnace [23]. The annealing at about 600 °C leads to the formation of Ge nanocrystals in the film matrix, which is formed by a crystallized mixture of two phases, the Ge in TiO2 anatase phase and the rutile phase (Ti in GeO2

Experimental determination of the light-trapping-induced absorption enhancement factor in DSSC photoanodes

• Serena Gagliardi and
• Mauro Falconieri

Beilstein J. Nanotechnol. 2015, 6, 886–892, doi:10.3762/bjnano.6.91

• index of the anatase phase of titania. When the electrode is under real working conditions in the cell, it is immersed in the electrolyte solution that presumably reduces the absorption enhancement due to the LT, partially matching the titania refractive index. Therefore, the maximum enhancement factor

Transformation of hydrogen titanate nanoribbons to TiO₂ nanoribbons and the influence of the transformation strategies on the photocatalytic performance

• Melita Rutar,
• Nejc Rozman,
• Matej Pregelj,
• Carla Bittencourt,
• Romana Cerc Korošec,
• Andrijana Sever Škapin,
• Aleš Mrzel,
• Srečo D. Škapin and
• Polona Umek

Beilstein J. Nanotechnol. 2015, 6, 831–844, doi:10.3762/bjnano.6.86

• calcinating in air, the photocatalytic performance of the investigated TiO2 NRs increased with an increased content of anatase. In contrast, the photocatalytic performance of the N-doped TiO2 NRs showed no dependence on the calcination temperature. An additional comparison showed that the N-doping

• titanate 1D nanostructures such as nanotubes [9][12], nanowires [13], nanofibers or nanoribbons [12] (NR) morphologies can be obtained. Transformations from the layered titanate structure to TiO2-B and then to the anatase structure (H2Ti3O7 → TiO2-B → anatase) are considered to be topotactic reactions [14

• low calcination temperatures (ca. 400 °C) results in the formation of a metastable TiO2-B phase [8][16] which at higher temperatures transforms to anatase [17][18][19]. Transformations conducted under reflux or hydrothermal conditions in neutral and acidic environment affect the surface of the

Tm-doped TiO₂ and Tm₂Ti₂O₇ pyrochlore nanoparticles: enhancing the photocatalytic activity of rutile with a pyrochlore phase

• Desiré M. De los Santos,
• Javier Navas,
• Teresa Aguilar,
• Antonio Sánchez-Coronilla,
• Concha Fernández-Lorenzo,
• Rodrigo Alcántara,
• Jose Carlos Piñero,
• Ginesa Blanco and
• Joaquín Martín-Calleja

Beilstein J. Nanotechnol. 2015, 6, 605–616, doi:10.3762/bjnano.6.62

• spectroscopy and UV–vis spectroscopy. For the samples annealed at 773 and 973 K, anatase phase TiO2 was obtained, predominantly internally doped with Tm3+. ICP–AES showed that a doping concentration of up to 5.8 atom % was obtained without reducing the crystallinity of the samples. The presence of Tm3+ was

• scan conditions were from 20 to 75° with a resolution of 0.025°, taken at 40 kV and 30 mA. From the patterns obtained, the anatase and rutile mass fraction, the average crystallite size, the unit cell volume and the specific surface area were semiquantitatively estimated. The mass fraction of the

• anatase phase was calculated using the following equation: where IA is the intensity of the reflection of the (101) plane for the anatase phase, and IR is the intensity of the reflection of the (110) plane for the rutile phase [14]. To determine the mass fraction of the rutile phase (fR), only the

Palladium nanoparticles anchored to anatase TiO₂ for enhanced surface plasmon resonance-stimulated, visible-light-driven photocatalytic activity

• Kah Hon Leong,
• Hong Ye Chu,
• Shaliza Ibrahim and
• Pichiah Saravanan

Beilstein J. Nanotechnol. 2015, 6, 428–437, doi:10.3762/bjnano.6.43

• possesses an appropriate band gap that ensure the simultaneous formation of superoxide anions (•O2−) and hydroxyl (•OH) radicals for the oxidation of organic compounds [6]. Despite all these advantages, TiO2 has two major drawbacks, which are (1) a wide band gap (ca. 3.2 eV for anatase) that restricts the

• -dimensional anatase TiO2/Ag, which exhibited an excellent photocatalytic activity with almost 100% degradation of 2,4-dichlorophenol within 2 h [26]. Likewise, Hou et al. reported a 9-fold improvement in the photocatalytic decomposition rate of methyl orange driven by a photocatalyst consisting of robust

• through Pd NPs onto anatase TiO2 for the enhancement of visible-light-driven photocatalysis. Results and Discussion Synthesis of Pd/TiO2 through solar-assisted photodeposition The Pd/TiO2 nanoparticles were synthesized through photodeposition using solar energy. The irradiation with sunlight was

A reproducible number-based sizing method for pigment-grade titanium dioxide

• Ralf Theissmann,
• Manfred Kluwig and
• Thomas Koch

Beilstein J. Nanotechnol. 2014, 5, 1815–1822, doi:10.3762/bjnano.5.192

• crystallographic phase, anatase, or the high-temperature crystallographic phase, rutile. The chloride process leads to formation of rutile phase particles due to the high temperatures of the combustion process. Both phases have a number of advantages and disadvantages, which lead to their typical applications

• . Preferred fields of application for rutile pigments are coatings, paints, plastics and building materials, whereas anatase pigments are mainly used in cosmetics, pharmaceuticals or food. One of the most important properties of titanium dioxide is its UV absorption, which protects human skin against sunburn

• needed [3]. This study focuses on two commercially available pigments, KRONOS K2360 and KRONOS K1171. The former is a pigment with a rutile structure for use in coatings and paints, while the latter is a food-grade pigment with an anatase structure. We decided to develop a procedure that requires a

Microstructural and plasmonic modifications in Ag–TiO₂ and Au–TiO₂ nanocomposites through ion beam irradiation

• Venkata Sai Kiran Chakravadhanula,
• Yogendra Kumar Mishra,
• Venkata Girish Kotnur,
• Devesh Kumar Avasthi,
• Thomas Strunskus,
• Vladimir Zaporotchenko,
• Dietmar Fink,
• Lorenz Kienle and
• Franz Faupel

Beilstein J. Nanotechnol. 2014, 5, 1419–1431, doi:10.3762/bjnano.5.154

• films have been performed and it has been reported that under SHI irradiation, the crystallization evolves through the formation of TiO2 nanocrystals in rutile and anatase phases [37][45]. In a similar study an increase of the dielectric constant of the TiO2 film after 100 MeV Ag8+ ion irradiation has

• patterns. Although signatures for the change in the matrix are evident right from 300 °C through the diffuse intensities corresponding to the reflections of the anatase form of TiO2. At 500 °C, these appear as ring patterns confirming the crystallization of TiO2 into the anatase type. Conclusion In

DFT study of binding and electron transfer from colorless aromatic pollutants to a TiO₂ nanocluster: Application to photocatalytic degradation under visible light irradiation

• Corneliu I. Oprea,
• Petre Panait and
• Mihai A. Gîrţu

Beilstein J. Nanotechnol. 2014, 5, 1016–1030, doi:10.3762/bjnano.5.115

• are in place. We model TiO2 nanoparticles by a geometry optimized cluster with the molecular formula Ti24O50H4. Prior to optimization, the cluster was cut from the experimental anatase structure with (101) and (001) surfaces [44]. The optimization led to some slight distortions from the lattice

Functionalized nanostructures for enhanced photocatalytic performance under solar light

• Liejin Guo,
• Dengwei Jing,
• Maochang Liu,
• Yubin Chen,
• Shaohua Shen,
• Jinwen Shi and
• Kai Zhang

Beilstein J. Nanotechnol. 2014, 5, 994–1004, doi:10.3762/bjnano.5.113

• of anatase TiO2 had different photocatalytic activities. However, when partially terminated with fluorine, the three facets had similar photocatalytic activity in H2 evolution [40]. Engineering the morphology of semiconductors to preferably expose active facets is therefore a promising approach, yet

Growth and characterization of CNT–TiO₂ heterostructures

• Yucheng Zhang,
• Ivo Utke,
• Johann Michler,
• Gabriele Ilari,
• Marta D. Rossell and
• Rolf Erni

Beilstein J. Nanotechnol. 2014, 5, 946–955, doi:10.3762/bjnano.5.108

• in Equation 1 and Equation 2 were proposed. TTIP/H2O ALD results in amorphous TiO2 for substrate temperatures between 100 and 150 °C while for substrate temperatures higher than 180 °C the crystalline anatase phase is obtained. Generally, the organo-metallic precursor molecules for metal oxide ALD

• formation of a coalesced and conformal layer of an anatase phase after 750 cycles. This provides an ideal scenario to study nucleation and growth of TiO2 on CNTs, and especially assisted with the powerful TEM techniques, to investigate the interface that is crucial to applications based on the ensemble. In

• in the ELNES of the Ti_L2,3 and O_K edges between anatase and rutile TiO2, which could be modelled using real-space multiple-scattering calculations [57]. With all the advancements in the analytical TEM techniques and their application to characterization of carbon-based nanomaterials and metal/metal

Nanostructure sensitization of transition metal oxides for visible-light photocatalysis

• Hongjun Chen and
• Lianzhou Wang

Beilstein J. Nanotechnol. 2014, 5, 696–710, doi:10.3762/bjnano.5.82

• greatly prolonged lifetime of photoexcited carriers [36]. We also investigated the photoelectrochemical behavior of CdS sensitized TiO2 film with {001} facet enriched anatase nanocrystals [37]. Zhang et al. developed a double-sided CdS and CdSe quantum dot co-sensitized ZnO nanowire arrayed photoanode for

A visible-light-driven composite photocatalyst of TiO₂ nanotube arrays and graphene quantum dots

• Donald K. L. Chan,
• Po Ling Cheung and
• Jimmy C. Yu

Beilstein J. Nanotechnol. 2014, 5, 689–695, doi:10.3762/bjnano.5.81

• that TNAs and GQDs/TNAs exhibit the same diffraction peaks at 2θ of 25.3°, 36.9°, 37.8°, 38.5°, 48.0°, 53.9°, 55.0°, 62.7°, 68.8° and 70.6°. These peaks match very well with anatase TiO2 (JCPDS 21-1272). FTIR spectra were also obtained to study the chemical structures of the products (Figure S2

• fabricated by covalently bonding GQDs onto amine-modified TNAs. The GQDs/TNAs composite retains the highly ordered nanotube morphology and well crystallized anatase phase. The high visible-light photocatalytic activity could be attributed to photosensitization of TNAs by GQDs. This research shows the

Effects of the preparation method on the structure and the visible-light photocatalytic activity of Ag₂CrO₄

• Difa Xu,
• Shaowen Cao,
• Jinfeng Zhang,
• Bei Cheng and
• Jiaguo Yu

Beilstein J. Nanotechnol. 2014, 5, 658–666, doi:10.3762/bjnano.5.77

• photocatalytic activity under visible-light irradiation. But it is not surprising that the rate constant for P25 is only 0.007 min−1 because the other phase anatase (75%) is not active in the visible region. Generally, the photocatalytic degradation of dyes in water is mainly attributed to the photogenerated

Dye-sensitized Pt@TiO₂ core–shell nanostructures for the efficient photocatalytic generation of hydrogen

• Jun Fang,
• Lisha Yin,
• Shaowen Cao,
• Yusen Liao and
• Can Xue

Beilstein J. Nanotechnol. 2014, 5, 360–364, doi:10.3762/bjnano.5.41

• Discussion The Pt@TiO2 core–shell nanoparticles were prepared trough a hydrothermal process by using Pt nanoparticles and TiF4 as the precursor. The crystalline structure was determined by XRD, as shown in Figure 1. After the hydrothermal reaction, the TiO2 was transformed into anatase phase, which could be

• well indexed to the standard anatase TiO2 (JCPDS Card No. 83-2243). The three additional diffraction peaks shown in Figure 1 could be assigned to the face-centered metallic Pt phase, with the positions at 40.0o, 46.6o and 67.9o representing the spacing of the (111), (200) and (220) planes, respectively

• diameter of 30 nm, and the TiO2 shell thickness is around 60 nm. The HRTEM image (Figure 2C) indicates lattice distances of 0.228 nm and 0.341 nm, which correspond to the (111) spacing of the core Pt particle and the (101) spacing of the anatase TiO2 shell. The SEM image (Figure 2D) reveals that these core

Quantum size effects in TiO₂ thin films grown by atomic layer deposition

• Massimo Tallarida,
• Chittaranjan Das and
• Dieter Schmeisser

Beilstein J. Nanotechnol. 2014, 5, 77–82, doi:10.3762/bjnano.5.7

• properties. Although the detailed interpretation of XAS measurements is very complex and not yet completely achieved, it was shown that rutile, anatase and amorphous TiO2 films, as well as quantum-confined TiO2 nanostructures exhibit distinct features at both the O-K and the TM-L2,3 edges [10][14][15]. Here

• typical of either anatase or rutile TiO2 are absent in the XAS spectra of the ALD films [17]. These crystalline phases show a split structure for feature A; a strong and sharp peak B, and distinct pre-preak features PP. Features A′ and B′ are sharper and well separated in the crystalline phases, too

• [23]. It should be noticed that Ti-L2,3 spectra with typical features of anatase and rutile TiO2 were obtained with our ALD system when TTIP was used in connection with O2-plasma instead of water [17]. O-K edge of TiO2 thin films Differently from the Ti-L2,3 spectra, the O-K XAS edge is usually

Characterization of electroforming-free titanium dioxide memristors

• John Paul Strachan,
• J. Joshua Yang,
• L. A. Montoro,
• C. A. Ospina,
• A. J. Ramirez,
• A. L. D. Kilcoyne,
• Gilberto Medeiros-Ribeiro and
• R. Stanley Williams

Beilstein J. Nanotechnol. 2013, 4, 467–473, doi:10.3762/bjnano.4.55

• stoichiometric TiO2 film is predominantly amorphous with some small (<10 nm) anatase grains, while the bilayer film is amorphous with no observed structural ordering. Electrical measurements of both types of devices are shown in Figure 1. Both showed reversible bipolar resistance switching. The standard device

Kelvin probe force microscopy of nanocrystalline TiO₂ photoelectrodes

• Alex Henning,
• Gino Günzburger,
• Res Jöhr,
• Yossi Rosenwaks,
• Biljana Bozic-Weber,
• Catherine E. Housecroft,
• Edwin C. Constable,
• Ernst Meyer and
• Thilo Glatzel

Beilstein J. Nanotechnol. 2013, 4, 418–428, doi:10.3762/bjnano.4.49

• absorption coefficient, implying a maximum SPV for super-bandgap illumination. Depending on the bandgap type, either direct or indirect, the SPV curve is fitted with the corresponding relation [18][47]: where h is the Planck constant and ν is the frequency of the light. For anatase TiO2, an indirect bandgap

• material [48], α is therefore expected to show a quadratic dependence on the illumination wavelength for energies just above the bandgap. Figure 5a presents an SPS measurement taken on a cluster of sintered anatase particles showing a quadratic dependence on the wavelength. By linear fitting, a bandgap

• calculations for N719 [38] and N3 [42][63] adsorbed on anatase plane-surface. However, for a complete DSC device the surface dipole may change due to screening by the surrounding electrolyte [64]. Figure 9a depicts the I–V characteristics for three different DSCs, a bare TiO2 solar cell with electrolyte and

Photocatalytic antibacterial performance of TiO₂ and Ag-doped TiO₂ against S. aureus. P. aeruginosa and E. coli

• Kiran Gupta,
• R. P. Singh,
• Ashutosh Pandey and
• Anjana Pandey

Beilstein J. Nanotechnol. 2013, 4, 345–351, doi:10.3762/bjnano.4.40

• that the annealed sample of TiO2 has both anatase and rutile phases while only an anatase phase was found in Ag-doped TiO2 nanoparticles. The decreased band-gap energy of Ag-doped TiO2 nanoparticles in comparison to TiO2 nanoparticles was investigated by UV–vis spectroscopy. The rate of recombination

• microorganisms including bacteria, fungi and viruses, because it has high photoreactivity, broad-spectrum antibiosis and chemical stability [1][2][3][4][5][6]. The photocatalytic activity of annealed TiO2 sturdily depends upon its existing phase, i.e., anatase, rutile, brokite. The anatase phase shows an

• and Ag-doped TiO2 nanoparticles. The crystal size of as-prepared TiO2 and Ag-doped TiO2 nanoparticles were calculated by the Scherrer equation based on the wide-angle XRD as shown in Figure 1. The typical anatase phase was observed in the case of Ag-doped TiO2 while in the case of pure annealed TiO2

Near-field effects and energy transfer in hybrid metal-oxide nanostructures

• Ulrich Herr,
• Barat Achinuq,
• Cahit Benel,
• Giorgos Papageorgiou,
• Manuel Goncalves,
• Johannes Boneberg,
• Paul Leiderer,
• Paul Ziemann,
• Peter Marek and
• Horst Hahn

Beilstein J. Nanotechnol. 2013, 4, 306–317, doi:10.3762/bjnano.4.34

• 1000 °C during the process. The composition of the NPs was controlled by energy-dispersive X-ray spectroscopy. Figure 2 shows the X-ray diffraction patterns of the as-prepared TiO2:Eu NPs with varying composition. For Eu concentrations below 0.56 atom % we find predominantly the anatase structure

• TiO2:Eu nanophosphors produced by the CVR method. For low Eu concentrations, only the anatase phase is found, whereas for higher concentrations a mixture of anatase and rutile can be observed. Normalized emission spectra of Eu3+ in TiO2 under excitation at 330 or 390 nm. Excitation spectrum of TiO2:Eu

Nanostructure-directed chemical sensing: The IHSAB principle and the dynamics of acid/base-interface interaction

• James L. Gole and
• William Laminack

Beilstein J. Nanotechnol. 2013, 4, 20–31, doi:10.3762/bjnano.4.3

• are readily oxidized to SnOx (x = 2,4) and CuxO (x = 1,2) as demonstrated by XPS measurements [23]. The initially introduced titania (anatase) may be crystalline; however, we cannot be certain of this crystallinity after deposition to the PS interface. The untreated PS hybrid structures are exposed to

Towards atomic resolution in sodium titanate nanotubes using near-edge X-ray-absorption fine-structure spectromicroscopy combined with multichannel multiple-scattering calculations

• Carla Bittencourt,
• Peter Krüger,
• Maureen J. Lagos,
• Xiaoxing Ke,
• Gustaaf Van Tendeloo,
• Chris Ewels,
• Polona Umek and
• Peter Guttmann

Beilstein J. Nanotechnol. 2012, 3, 789–797, doi:10.3762/bjnano.3.88

• -edge NEXAFS spectrum of the (Na,H)TiNTs shares common general features with the spectra recorded on anatase and SrTiO3 (Figure 3): they are composed of distinguishable peaks in the range between 455 and 470 eV corresponding to excitations of the Ti 2p states into the empty Ti 3d states [35]. Due to the

• hydrothermal process used to synthesize the tubes, the binding energy of Ti 2p photoemission lines are shifted slightly to lower binding energy, showing that the local environment around the Ti ions in the (Na,H)TiNTs is different from that in the anatase-type TiO2 (see also Supporting Information File 1

• energy splitting of the fine structure in the L3–eg band. From Figure 3a, we can see that this value is 0, 0.44 and 0.82 eV, respectively, for SrTiO3, (Na,H)TiNTs and anatase. Krüger showed that the L3–eg peak splitting in TiO2 is a band-structure effect, which mainly reflects the connectivity of the

Reduced electron recombination of dye-sensitized solar cells based on TiO₂ spheres consisting of ultrathin nanosheets with [001] facet exposed

• Hongxia Wang,
• Meinan Liu,
• Cheng Yan and
• John Bell

Beilstein J. Nanotechnol. 2012, 3, 378–387, doi:10.3762/bjnano.3.44

• Hongxia Wang Meinan Liu Cheng Yan John Bell School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, 2 George Street, GPO Box 2434, Brisbane, QLD 4001, Australia 10.3762/bjnano.3.44 Abstract An anatase TiO2 material with hierarchically structured spheres

• process of electron recombination is mainly dominated by the interaction between the electron at the surface of TiO2 and I3− ions in the electrolyte. Generally, the TiO2 used in DSCs is based on the anatase phase with the [101] facet exposed, due to the robust stability of this surface compared to other

• crystal facets [4]. It has been reported that the average surface energies of the different facets of anatase TiO2 lie in the order of [001] (0.90 J/m2) > [100] (0.53 J/m2) > [101] (0.44 J/m2) [5]. Apparently, the lowest surface energy of the [101] facet is the most stable surface of the TiO2 material

Mesoporous MgTa₂O₆ thin films with enhanced photocatalytic activity: On the interplay between crystallinity and mesostructure

• Jin-Ming Wu,
• Igor Djerdj,
• Till von Graberg and
• Bernd M. Smarsly

Beilstein J. Nanotechnol. 2012, 3, 123–133, doi:10.3762/bjnano.3.13

• considering the turnover frequency of such photocatalysts, the optimized activity of the present nanoarchitectured MgTa2O6 thin film was ca. four times that of analogous anatase TiO2 films with ordered mesopores. Our study demonstrated that high crystallinity and well-developed mesoporosity have to be

• copolymer EO106–PO70–EO106), which forms larger mesopores compared to most other commercially available templates, and to a previously reported type of anatase TiO2 thin film with ordered mesopores, examples of which are widely used as photocatalysts [15][16]. Recently, a further class of block copolymers

• the presence of various oxide films, is illustrated in Figure 8b. Here, two oxide films, namely, a mesoporous anatase film and a F127-templated MgTa2O6 film, were included as references. The fabrication and characterization of the mesoporous anatase film is reported elsewhere [21]. F127-templated

Self-assembled monolayers and titanium dioxide: From surface patterning to potential applications

• Yaron Paz

Beilstein J. Nanotechnol. 2011, 2, 845–861, doi:10.3762/bjnano.2.94

• ; Introduction Photocatalytic degradation of pollutants is attracting increasing attention. In this context, anatase-phase titanium dioxide is regarded as the photocatalyst of choice, due to its low cost, nontoxicity, and relatively high efficiency, which make it suitable not only for air and water

• grafting density with respect to chemisorption by conventional methods (2.8–3.0 molecules per nm2 versus 4.3–4.8 molecules per nm2). It is worth mentioning that a study on organosilane monolayers formed on the surfaces of zirconia and titania (anatase and rutile), by a gas–phase process employing

• titanium dioxide was not in the photocatalytic anatase phase but rather it was amorphous. This amorphous phase can be transformed to anatase; however, it requires temperatures no less than 300 °C, which are expected to severely damage the underlying organic SAM. Generally speaking, there are three main