Rutile TiO2 Nanoparticles Research Articles

Synthesis of nanostructured TiO2 thin films with highly enhanced photocatalytic activity by atom beam sputtering

Nanostructured TiO2 thin films with highly enhanced photocatalytic activity were prepared by atom beam sputtering technique. The effects of thermal annealing on the structural, morphological and photocatalytic properties of TiO2 thin films were investigated using X-ray diffraction, atomic force microscopy, field emission scanning electron microscopy, Raman spectroscopy and UV-visible absorption spectroscopy. X-ray diffraction studies showed that the as-deposited TiO2 thin films made up of anatase TiO2 nanoparticles transformed into anatase/ rutile mixed-phase TiO2 nanoparticles upon annealing. Field emission scanning electron microscopy and atomic force microscopy studies revealed growth of TiO2 nanoparticles from 16 nm to 29 nm upon annealing at 600 o C. The photocatalytic activities of the nanostructured TiO2 thin films were studied by monitoring photocatalytic degradation of methylene blue in water. Our results showed that the as-deposited nanostructured TiO2 thin films exhibited highly enhanced photocatalytic efficiency as compared to the annealed samples. The mechanism underlying the enhanced photocatalytic activity of nanostructured TiO2 thin film is tentatively proposed.

Moving into advanced nanomaterials. Toxicity of rutile TiO2 nanoparticles immobilized in nanokaolin nanocomposites on HepG2 cell line

Immobilization of nanoparticles on inorganic supports has been recently developed, resulting in the creation of nanocomposites. Concerning titanium dioxide nanoparticles (TiO2 NPs11TiO2 NPs: Titanium dioxide nanoparticles), these have already been developed in conjugation with clays, but so far there are no available toxicological studies on these nanocomposites. The present work intended to evaluate the hepatic toxicity of nanocomposites (C-TiO222C-TiO2: Rutile TiO2 NPs immobilized in nanokaolin clay substrates), constituted by rutile TiO2 NPs immobilized in nanokaolin (NK33NK: Nanokaolin clay) clay, and its individual components.These nanomaterials were analysed by means of FE-SEM44FE-SEM: Field Emission Scanning Electron Microscopy and DLS55DLS: Dynamic Light Scattering analysis for physicochemical characterization. HepG2 cells were exposed to rutile TiO2 NPs, NK clay and C-TiO2 nanocomposite, in the presence and absence of serum for different exposure periods. Possible interferences with the methodological procedures were determined for MTT,66MTT: 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide assay neutral red uptake, alamar blue (AB), LDH,77LDH: Lactate dehydrogenase assay and comet assays, for all studied nanomaterials. Results showed that MTT, AB and alkaline comet assay were suitable for toxicity analysis of the present materials after slight modifications to the protocol. Significant decreases in cell viability were observed after exposure to all studied nanomaterials. Furthermore, an increase in HepG2 DNA damage was observed after shorter periods of exposure in the absence of serum proteins and longer periods of exposure in their presence. Although the immobilization of nanoparticles in micron-sized supports could, in theory, decrease the toxicity of single nanoparticles, the selection of a suitable support is essential. The present results suggest that NK clay is not the appropriate substrate to decrease TiO2 NPs toxicity. Therefore, for future studies, it is critical to select a more appropriate substrate for the immobilization of TiO2 NPs.

Modification of Charge Trapping at Particle/Particle Interfaces by Electrochemical Hydrogen Doping of Nanocrystalline TiO2

Particle/particle interfaces play a crucial role in the functionality and performance of nanocrystalline materials such as mesoporous metal oxide electrodes. Defects at these interfaces are known to impede charge separation via slow-down of transport and increase of charge recombination, but can be passivated via electrochemical doping (i.e., incorporation of electron/proton pairs), leading to transient but large enhancement of photoelectrode performance. Although this process is technologically very relevant, it is still poorly understood. Here we report on the electrochemical characterization and the theoretical modeling of electron traps in nanocrystalline rutile TiO2 films. Significant changes in the electrochemical response of porous films consisting of a random network of TiO2 particles are observed upon the electrochemical accumulation of electron/proton pairs. The reversible shift of a capacitive peak in the voltammetric profile of the electrode is assigned to an energetic modification of trap states at particle/particle interfaces. This hypothesis is supported by first-principles theoretical calculations on a TiO2 grain boundary, providing a simple model for particle/particle interfaces. In particular, it is shown how protons readily segregate to the grain boundary (being up to 0.6 eV more stable than in the TiO2 bulk), modifying its structure and electron-trapping properties. The presence of hydrogen at the grain boundary increases the average depth of traps while at the same time reducing their number compared to the undoped situation. This provides an explanation for the transient enhancement of the photoelectrocatalytic activity toward methanol photooxidation which is observed following electrochemical hydrogen doping of rutile TiO2 nanoparticle electrodes.

Growth of anatase and rutile phase TiO2 nanoparticles using pulsed laser ablation in liquid: Influence of surfactant addition and ablation time variation

Titanium dioxide (TiO2) nanoparticles were grown using nanosecond pulsed laser ablation of Ti target in DI water and in 0.001M sodium dodecyl sulfate (SDS) surfactant aqueous solution. Growth was carried out with varying ablation times i. e. 30min, 60min and 90min. The objective of our study was to investigate the influence of variations in liquid ambience conditions on the growth of the nanoparticles in a pulsed laser ablation in liquid (PLAL) process. Size, composition and optical properties of the grown TiO2 nanoparticles were investigated using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), optical absorption, photoluminescence (PL) spectroscopy and X-ray diffraction (XRD) studies. The obtained nanoparticles of TiO2 were found almost spherical in shape and polycrystalline in nature in both the liquid mediums i.e. DI water and aqueous solution of surfactant. Nanoparticles number density was also found to increase with increasing ablation time in both the liquid mediums. However crystalline phase of the grown TiO2 nanoparticles differs with the change in liquid ambience conditions. Selected area electron diffraction (SAED), PL and XRD studies suggest that DI water ambience is favorable for the growth of anatase phase TiO2 nanoparticles for all ablation times. While Surfactant added water ambience is favorable for the growth of rutile phase TiO2 nanoparticles but for shorter ablation times of 30min and 60min only, for longer ablation time of 90min anatase phase was also observed along with the rutile phase TiO2 nanoparticles. The formation of anatase phase in DI water and rutile and anatase phase in aqueous solution of surfactant is explained on the basis of varying thermodynamic conditions with the two different liquid ambiences and different ablation times.

Evaluating photodegradation properties of anatase and rutile TiO2 nanoparticles for organic compounds

TiO2 nanoparticles were synthesized via a simple sol-gel method and calcined at 300°C, 500°C and 800°C temperatures. SEM images show well-defined particles which get agglomerated at higher calcination temperatures. Two types of nanostructures, spherical and rice-grain shape are significantly observed through TEM. The spherical nanostructures is estimated the particle size to be 73.99nm with the larger BET surface area of 205m2/gm in all the three samples. The rice-grain shape particles are confined to 12–13nm only in samples calcined at 300°C. The XRD investigations of these TiO2 nanoparticles confirm the tetragonal form of anatase and rutile phases of TiO2. These results suggest that, TiO2 sample calcinated at 300°C temperature showed anatase phase of good crystallinity with smaller crystallite size. FTIR spectra showed the TiO2 peaks in characteristics region are due to TiOTi metal bond in all the samples. The morphology display in the AFM image of powder sample exhibit well structured nano-surface. UV–vis spectra show stronger absorption in the visible region. The emission spectra of anatase TiO2 nanoparticle of sample calcinated at 300°C temperature has been split into sharp peaks confirming well-defined lattices site in particles and better luminescence activity of material. The sharp emission peak is due to reduced recombination rate which enhances photocatalytic properties. The active anatase Titania calcined at 300°C temperature show remarkably high rate of photocatalytic of methylene blue (73%) and methyl orange (69%) under visible light irradiation.

Titanium dioxide nanoparticle coating of polymethacrylate-based chromatographic monoliths for phosphopetides enrichment

Metal oxide affinity chromatography has been one of the approaches for specific enrichment of phosphopeptides from complex samples, based on specific phosphopeptide adsorption forming bidentate chelates between phosphate anions and the surface of a metal oxide, such as TiO2, ZrO2, Fe2O3, and Al2O3. Due to convective mass transfer, flow-independent resolution and high dynamic binding capacity, monolith chromatographic supports have become important in studies where high resolution and selectivity are required. Here, we report the first synthesis and characterization of immobilisation of rutile TiO2 nanoparticles onto organic monolithic chromatographic support (CIM-OH-TiO2). We demonstrate the specificity of CIM-OH-TiO2 column for enrichment of phosphopeptides by studying chromatographic separation of model phosphorylated and nonphosphorylated peptides as well as proving the phosphopeptide enrichment of digested bovine α-casein. The work described here opens the possibility for a faster, more selective enrichment of phosphopeptides from biological samples that will enable future advances in studying protein phosphorylation.

Low-temperature synthesis and adsorption property of rutile TiO2 nanoparticles with mesoporous structure

ABSTRACTRutile nano-TiO2 with mesoporous structure was prepared by a simple precipitation method at low temperature with no need of calcination, using titanium sulfate as Ti source, and the product was characterized. The prepared TiO2 nanoparticles are of rutile crystal form (XRD) with an average particle size of 5.0 nm (TEM), a specific surface area of 368 m2/g (Brunauer-Emmett-Teller), and an average pore size of 4.2 nm (Barrett-Joyner-Halenda). Their adsorption property for cationic dye methylene blue was studied systematically. The adsorption kinetics is close to the pseudo-second order kinetic model and the adsorption isotherm is close to the Redlich-Peterson isotherm.

Interactions of titania based nanoparticles with silica and green-tea: Photo-degradation and -luminescence

An effective way to modify the photocatalytic activity of both anatase and rutile TiO2 nanoparticles by coating the surface with either an inorganic (SiO2/silica) or organic (green-tea) layer using a chemical approach is demonstrated. Tetraethyl orthosilicate (TEOS) was used to cover the surface of TiO2 with silica which facilitates the inhibition of photocatalytic activity, ensuring its application in sunscreens by blocking the reactive oxygen species (ROS). Green-tea extract, rich in epigallocatechin gallate (EGCG), was used to coat/stabilize nano-sized TiO2. The morphology of these coatings was revealed by transmission electron microscopy (TEM) and by energy dispersive spectroscopy (EDS) mapping. These studies showed good coverage for both types of coating, but with somewhat better uniformity of the coating layer on rutile TiO2 compared to anatase due to its more uniform particle geometry. The effectiveness of each coating was evaluated by photodegradation of an organic dye (methyl orange). These studies showed rutile_polyphenol exhibits the highest photocatalytic activity among rutile forms which validates its feasibility to be used in photodegradation.

Exposure to TiO2 nanoparticles increases Staphylococcus aureus infection of HeLa cells.

BackgroundTitanium dioxide (TiO2) is one of the most common nanoparticles found in industry ranging from food additives to energy generation. Approximately four million tons of TiO2 particles are produced worldwide each year with approximately 3000 tons being produced in nanoparticulate form, hence exposure to these particles is almost certain.ResultsEven though TiO2 is also used as an anti-bacterial agent in combination with UV, we have found that, in the absence of UV, exposure of HeLa cells to TiO2 nanoparticles significantly increased their risk of bacterial invasion. HeLa cells cultured with 0.1 mg/ml rutile and anatase TiO2 nanoparticles for 24 h prior to exposure to bacteria had 350 and 250 % respectively more bacteria per cell. The increase was attributed to bacterial polysaccharides absorption on TiO2 NPs, increased extracellular LDH, and changes in the mechanical response of the cell membrane. On the other hand, macrophages exposed to TiO2 particles ingested 40 % fewer bacteria, further increasing the risk of infection.ConclusionsIn combination, these two factors raise serious concerns regarding the impact of exposure to TiO2 nanoparticles on the ability of organisms to resist bacterial infection.Electronic supplementary materialThe online version of this article (doi:10.1186/s12951-016-0184-y) contains supplementary material, which is available to authorized users.

Nanoparticle-Assisted Water-Flooding in Berea Sandstones

The use of nanoparticles to improve reservoir characterization or to enhance oil recovery (EOR) has recently received intensive interest; however, there are still many unresolved questions. This work reports a systematic study of the effect of rutile TiO2 nanoparticle-assisted brine flooding. Rutile ellipsoid TiO2 nanoparticles were synthesized and stabilized by trisodium citrate dihydrate for brine flooding of water-wet Berea sandstone cores. Careful characterization of the rock samples and nanomaterials before and after the flooding was conducted, and the relative contributions to the modified flooding results from the stabilizer and the nanoparticles of different concentrations were examined. The oil recovery performance was evaluated both at the breakthrough (BT) point and at the end of flooding (∼3.2 pore volumes). Nanoparticle migration behavior was also investigated in order to understand the potential mechanisms for oil recovery. The results showed that both nanoparticle transport rate and EOR eff...

Mass production and application of TiO2@CaCO3 composites in interior emulsion coatings

Abstract In this paper, rutile TiO2@CaCO3 composites were in-situ synthesized by disaggregation and deposition of commercial TiO2 in alkaline Ca(OH)2 slurry via a convenient and easy industrialized carbonation method. Field emission scanning electron microscopy and X-ray diffraction were applied to characterize the surface morphology and crystalline phases of the TiO2@CaCO3 composites, and the results showed that a coating layer of rutile TiO2 nanoparticles was formed on the surface of calcite CaCO3. As confirmed by the thermal gravimetric analysis and acid-resistance, the composites had better thermal stability and acid-resistance compared with CaCO3. The UV–vis absorption spectra showed that rutile TiO2@CaCO3 composites possessed similar ultraviolet absorption capacity with TiO2. The contrast ratios of the coatings were high enough, and it remained 0.934 when rutile TiO2@CaCO3-15 completely substituted TiO2. Therefore, rutile TiO2@CaCO3 could partly substitute TiO2 applied as pigments in interior emulsion coatings.

Effects of heat treatment on the atomic structure and surface energy of rutile and anatase TiO2 nanoparticles under vacuum and water environments

Nanomaterials have become a widely used group of materials in many chemical engineering applications owing to their ability to provide an enhanced level of functional properties compared to their crystalline and bulk counterparts. Here we report fundamental level advancements on how the anatase and rutile phase of TiO2 nanoparticles chemo-thermally respond between room temperature and the melting temperature under both vacuum and water environments. The current study is based on using molecular dynamics (MD) simulations. We present results on the equilibrium crystal morphology of these phases, structural and surface energy of TiO2 nanoparticles in the size range of 2–6nm under different temperatures. Thermodynamic and structural properties, in the form of potential energy and Radial Distribution Functions (RDF’s) respectively, are calculated for both forms of TiO2 nanoparticles. The temperature associated with the melting transition increased with an increase in the particle size in both the phases. The potential energy change associated with the melting transition for anatase was seen to be less than that for rutile nanoparticles. Also the temperature at which the RDF’s began to stretch and broaden was observed to be lower for the case of anatase than rutile, suggesting that rutile attains the most thermal stable phase for the nano particle sizes considered in this study. Structural changes in anatase and rutile nanoparticles under different temperatures revealed that non-spherical (rod-like) rutile nanoparticles tend to be thermodynamically more stable. Surface energy influences the shape of TiO2 nanoparticles at different temperatures. The increase in the surface energy of nanoparticles under vacuum when compared with that of water environment is higher for the anatase phase than the rutile phase of nanoparticle sizes studied here. The fundamental level simulation results reported here provide a strong platform for potentially accounting for the effects of atomic-scale phase characteristics of TiO2 nanoparticles and surface energy under different temperature fields in nano processing applications and related multi-scale modelling approaches in future.

IMPROVEMENT OF CO2 PURIFYING SYSTEM BY PHOTOCATALYST FOR APPLICATION IN MICROALGAE CULTURE TECHNOLOGY

By reactive grinding method Vanadium-doped rutile TiO2 nanoparticle material was obtained with an average particle size of 20‐40nm, the Brunauer–Emmet–Teller (BET) specific surface area about 20 m2g−1 and it absorbed strongly in the UV region and increased at the visible wavelength of 430 – 570 nm. This study focused on the improvement of exhaust gas treatment from coal-fired flue gas of the traditional adsorption-catalysis system (Modular System for Treating Flue Gas - MSTFG) by using the V2O5/TiO2 Rutile as photocatalyst. The results showed that integrating both catalytic systems mentioned above increased the gas treatment efficiency: CO from 77 % to over 98 %, NOx from 50 % to 93 %, SO2 was absent as opposed to the input gas component. Also it showed that V2O5/TiO2 Rutile integrated with MSTFG has got high efficiency of CO treatment, also secured the high obtained CO2 concentration as a valuable carbon source for microagal mass culture as well as saving energy and simplifying devices.

Effect of coating layers on nano-TiO2 particles on the preparation of nanocrystalline λ-Ti3O5 by carbonthermal reduction

Three different kinds of rutile TiO2 nanoparticles with different surface coating conditions were prepared by precipitation method for synthesizing λ-Ti3O5. The effect of surface layers on nano rutile TiO2 particles on the preparation of λ-Ti3O5 was firstly investigated. X-ray diffraction, scanning electron microscope, energy dispersive spectrometer and transmission electron microscope were used to characterize these powders. The nano rutile TiO2 powders were mixed with carbon black separately and then annealed at an isothermal heat condition. The phase structures of the products demonstrate that high purity nanocrystalline λ-Ti3O5 powders can be synthesized by carbothermal reduction of the Al2O3–SiO2 dual-coated TiO2 powders, but not by the uncoated and SiO2-coated TiO2 powders. Thus, the coating layers of the TiO2 nanoparticles played a decisive role in the formation of nanocrystalline λ-Ti3O5. It proposed that both of the coating layers and metal ion (i.e. Al3+) make a contribution to stabilize the metastable phase λ-Ti3O5 to ambient temperature in the carbothermal reduction of the TiO2/C system. This study provided considerable insights into the preparation of nanocrystalline λ-Ti3O5.

Engineering the surface of rutile TiO2 nanoparticles with quantum pits towards excellent lithium storage

Unique rutile TiO2 nanoparticles with quantum pits have been successfully synthesized by a facile solution and subsequent thermal annealing method. The resultant rutile TiO2 nanoparticles exhibit excellent lithium storage properties.

Encapsulation of curcumin over carbon dot coated TiO2 nanoparticles for pH sensitive enhancement of anticancer and anti-psoriatic potential

The surface engineering of rutile phase TiO2 nanoparticles was performed by carbogenic carbon dots for biological applications.

Fabrication of phase and morphology controlled pure rutile and rutile/anatase TiO2 nanostructures in functional ionic liquid/water

In this paper, pure rutile and anatase-rutile TiO2 nanoparticles have been successfully synthesised via a green route by hydrolysis of titanium tetrachloride with room temperature acidic ionic liquid 3-methyl-1-(3-sulfonylpropyl) imidazolium trifluoromethanesulfonate [HO3S(CH2)3MIM][CF3SO3] in aqueous medium. The influence of pH of the solution by varying molar ratio of substrate and ionic liquid has been investigated in both sol⿿gel and hydrothermal synthesis of TiO2 with significant variation in phase, phase composition (ratio of rutile to anatase) and morphology as indicated by various structural analysis such as XRD, TEM, BET, Raman and UV⿿vis absorption spectroscopy. The results indicate formation of a bunch of aligned thin flaky nano-rods of TiO2 which look like nano-flowers with a crystal size of 3⿿5nm by sol⿿gel method, while in case of hydrothermal method well-defined rutile solid nanorods of TiO2 were formed with variable length in the range of 120⿿170nm and 20⿿24nm in width. The photocatalytic activity of the prepared TiO2 samples has been determined by the photodegradation of methyl orange dye (20ppm) under UV light. Best photocatalytic activity was exhibited by sample S-2 prepared via sol⿿gel method.

Hierarchical Nanostructured Pt8Ti-TiO2/C as an Efficient and Durable Anode Catalyst for Direct Methanol Fuel Cells

A catalyst for the electrochemical oxidation of methanol in direct methanol fuel cells (DMFCs) comprising Pt8Ti intermetallic nanoparticles dispersed in carbon nanorods (Pt8Ti-TiO2/C) is presented. The catalyst consists of Pt8Ti and rutile TiO2 nanoparticles dispersed in nitrogen-doped carbon hierarchical nanostructures. The Pt8Ti-TiO2/C catalyst showed a 50 mV positive onset potential and 10 times higher specific activity than a commercial Pt/C catalyst. Using a half-cell experiment, we show that Pt8Ti intermetallic nanoparticles greatly enhance the methanol oxidation activity and durability in comparison to a Pt/C commercial catalyst. More importantly, a DMFC anode constructed with Pt8Ti-TiO2/C catalyst showed 4.6 times higher power density than a commercial Pt/C catalyst at 0.35 V and 333 K. Additionally, the Pt8Ti-TiO2/C catalyst displayed superior durability in comparison to the Pt/C catalyst. Pt8Ti-TiO2/C showed an electrochemical surface area decay of 23% at the end of 3000 CV cycles, whereas the P...

One step preparation of highly dispersed TiO2 nanoparticles

A facile approach was developed to prepare highly dispersed TiO2 nanoparticles with selected phase. The crystallization phase of the nanoparticles can be easily tuned from anatase to rutile by the dosage of hydrochloric acid in the reaction system. The crystallite size of the as-prepared anatase TiO2 nanoparticles was ca. 3.2 nm with high dispersion. A transparent TiO2 colloid was obtained by dispersing the as-prepared anatase TiO2 nanoparticles in deionized water without any organic additives added. The concentration of TiO2-H2O colloid can be as high as 1600 g/L. The optical transmittance of TiO2-H2O colloid with a low concentration was nearly 100% in the visible region. Furthermore, anatase TiO2 nanoparticles(TiO2-NPs) showed superior photocatalytic performance compared to rutile TiO2-NPs.

Improving high-altitude UV–Vis resistance of PBO braided tendons of NASA’s super pressure balloons

Super pressure balloons (SPBs) are used by the National Aeronautics and Space Administration (NASA) for ultra-long duration ballooning (ULDB) missions which carry various scientific explorations to support space and earth sciences research activities. The resistance to photo-degradation of load-bearing braided tendons of SPBs is critical to the success of ULDB missions. Recognizing the critical need to improve UV and visible light (UV–Vis) protective performance of p-phenylene-2, 6-benzobisoxazole (PBO) braids, North Carolina State University and NASA's Balloon Program collaborated to investigate the effectiveness of sheath extrusion method in improving the UV–Vis resistance of tendons. This study included two PBO tendon types – 48,000 (48k) denier tendons and 72,000 (72k) denier tendons. Using a sheath extrusion method, the tendons were covered with UV protective sheath of low-density polyethylene containing two types of UV inhibitors – TiO2 rutile nanoparticles and PolyOne PE White CC®. Bare and sheathed tendons were subjected to artificial UVB exposure in the lab as well as to both high altitude and ground exposure during flight missions conducted by NASA. Protection against radiation exposure was evaluated by determining the loss of tensile strength after exposure. UV–Vis protection of tendons improved with an increase in sheath thickness as well as UV inhibitor content in the sheath. The results also showed that 72k denier braids had higher resistance against UV degradation compared to 48k denier braids. In-flight exposure results confirmed the comparative UV protective performance of tendons exposed to accelerated artificial UVB exposure in lab. 72k denier tendon covered with sheath containing 10% PE White CC® (sheath thickness of 0.37 mm) experienced the lowest strength loss among all tendon samples to high-altitude exposure during flight missions. The study has also utilized UV–Vis transmittance of the sheath covering the braids as a method of evaluating the performance of the protective sheaths.