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1.
We report a hybrid photoelectrode fabricated by using single crystalline rutile TiO2 nanowires (NWs) inlaid with anatase TiO2 nanoparticles (NPs) for efficient dye-sensitized solar cells. For this purpose, ∼4-μm-thick vertically aligned NWs were synthesized on the FTO glass substrate through a solvothermal treatment. Then, as-prepared NW film was treated with the NP colloidal dispersion to construct the NW–NP film. In particular, the NWs offer a fast pathway for electron transport as well as light scattering effect. On the other hand, the inlaid NPs give an extra amount of space for the dye-uptake. Accordingly, the present NW–NP electrode exhibited 6.2% of the conversion efficiency, which corresponds to ∼48% improvement over the efficiency of the NP-DSC. We attribute this notable result to the synergetic effects of the enhanced light confinement, charge collection, and dye-loading. 相似文献
2.
《Materials Research Bulletin》2013,48(11):4738-4742
The synthesis of titanium dioxide nanoparticle (TiO2 NP) has gained importance in the recent years owing to its wide range of potential biological applications. The present study demonstrates the synthesis of TiO2 NPs by a metal resistant bacterium isolated from the coal fly ash effluent. This bacterial strain was identified on the basis of morphology and 16s rDNA gene sequence [KC545833]. The physico-chemical characterization of the synthesized nanoparticles is completely elucidated by energy dispersive X-ray analysis (EDAX), Fourier transform infrared spectroscopy (FTIR) and transmission and scanning electron microscopy (TEM, SEM). The crystalline nature of the nanoparticles was confirmed by X-RD pattern. Further, cell viability and haemolytic assays confirmed the biocompatible and non toxic nature of the NPs. The TiO2 NPs was found to enhance the collagen stabilization and thereby enabling the preparation of collagen based biological wound dressing. The paper essentially provides scope for an easy bioprocess for the synthesis of TiO2 NPs from the metal oxide enriched effluent sample for future biological applications. 相似文献
3.
Hybrid ZnO/TiO2 photoanodes for dye-sensitized solar cells were prepared by combining ZnO nanowire (NW) arrays and TiO2 nanoparticles (NPs) with the assistance of the ultrasonic irradiation assisted dip-coating method. Results show that the ultrasonic irradiation was an efficient way to promote the gap filling of TiO2 NPs in the interstices of ZnO NWs. Hybrid ZnO NW/TiO2 NP electrodes prepared with ultrasonic treatment exhibited better gap filling efficiency and higher visible absorptance. The overall conversion efficiency of the hybrid electrode was 0.79%, representing 35% improvement compared with that of the traditional one (0.58%). The enlarged surface area and improved attachments of TiO2 NPs onto the walls of ZnO NWs induced by the application of ultrasonic irradiation may be the underlying reason. Electrochemical impedance spectroscopy measurements indicated that hybrid electrodes combined the advantages of improved electron transport along the ZnO NWs and increased surface area provided by infiltrated TiO2 NPs, both of which are responsible for the improved cell efficiency. 相似文献
4.
Petra Kocbek Karmen Teskač Mateja E. Kreft Julijana Kristl 《Small (Weinheim an der Bergstrasse, Germany)》2010,6(17):1908-1917
Sunscreens containing ZnO and TiO2 nanoparticles (NPs) are increasingly applied to skin over long time periods to reduce the risk of skin cancer. However, long‐term toxicological studies of NPs are very sparse. The in vitro toxicity of ZnO and TiO2 NPs on keratinocytes over short‐ and long‐term applications is reported. The effects studied are intracellular formation of radicals, alterations in cell morphology, mitochondrial activity, and cell‐cycle distribution. Cellular response depends on the type of NP, concentration, and exposure time. ZnO NPs have more pronounced adverse effects on keratinocytes than TiO2. TiO2 has no effect on cell viability up to 100 μg mL?1, whereas ZnO reduces viability above 15 μg mL?1 after short‐term exposure. Prolonged exposure to ZnO NPs at 10 μg mL?1 results in decreased mitochondrial activity, loss of normal cell morphology, and disturbances in cell‐cycle distribution. From this point of view TiO2 has no harmful effect. More nanotubular intercellular structures are observed in keratinocytes exposed to either type of NP than in untreated cells. This observation may indicate cellular transformation from normal to tumor cells due to NP treatment. Transmission electron microscopy images show NPs in vesicles within the cell cytoplasm, particularly in early and late endosomes and amphisomes. Contrary to insoluble TiO2, partially soluble ZnO stimulates generation of reactive oxygen species to swamp the cell redox defense system thus initiating the death processes, seen also in cell‐cycle distribution and fluorescence imaging. Long‐term exposure to NPs has adverse effects on human keratinocytes in vitro, which indicates a potential health risk. 相似文献
5.
A. Azarian 《Journal of Experimental Nanoscience》2016,11(12):940-950
Copper oxide nanotubes decorated by TiO2 nanoparticles (CNTNs) were fabricated by simple three-step method. First, deposition of copper onto cellulose fibres, then thermal oxidation of copper and cellulose fibres and last simply mixing copper oxide nanotubes and TiO2 nanoparticles (NPs). Scanning electron microscopy, transmission electron microscopy and X-ray diffraction showed that the synthesised nanotubes were monoclinic-structured polycrystalline CuO with diameter and wall thickness of approximately 50~100 nm and 20~25 nm, respectively. Moreover, the diameter of the TiO2 NPs is about 20~30 nm. Optical properties of the solutions containing copper oxide nanotubes decorated by TiO2 NPs were studied. Discrete dipole approximation was used for the calculation of absorption, scattering and extinction cross sections of the deposited CNTNs on a glass substrate. Our simulation results show that there are good agreements between the experimental date and the simulation results. Moreover, the photocatalytic tests were done by methyl orange under visible light (λ = 633 nm) irradiation for prepared samples. 相似文献
6.
Small Au nanoparticles (NPs) with mean diameter of 4.1 nm were highly deposited on TiO2 films via a simple electrostatic self-assembly method. The physically separated Au NPs, with a high surface density of 6.3 × 1011 NPs/cm2, were mainly distributed on the top layer of porous TiO2 films. The deposition of Au NPs induced a negative shift (~ 100 mV) of the apparent flat band potential of Au-TiO2 electrodes. The charge separation efficiency of the TiO2 electrode increased from 72.1% to 88.5% by dispersing Au NPs. Whatever redox species were present in the electrolyte, the Au-TiO2 electrode had higher photovoltage than the TiO2 electrode. The photovoltage was very sensitive to added redox species such as O2, O3, and methanol, and the effect of adsorbed redox species on electron accumulation was discussed. The electrochemical impedance spectroscopic measurements revealed that the charge transfer resistance (Rct) of Au-TiO2 films was reduced to 16% of bare TiO2 electrode, and the decreased Rct corresponded to the increased photocatalytic activity of Au-TiO2 films. The beneficial role of uniformly dispersed small Au NPs on the charge separation was discussed. By modifying TiO2 films with small Au NPs, the photocatalytic activity of TiO2 films for formaldehyde degradation increased about 2.5 times. 相似文献
7.
A. Gomathi 《Materials Research Bulletin》2010,45(12):1894-1898
Polyoctasilsesquioxane (POSS) has been employed to covalently functionalize nanostructures of TiO2, ZnO and Fe2O3 as well as carbon nanotubes, nanodiamond and graphene to enable their dispersion in polar solvents. Covalent functionalization of these nanostructures with POSS has been established by electron microscopy, EDAX analysis and infrared spectroscopy. On heating the POSS-functionalized nanostructures, silica-coated nanostructures are obtained. POSS-functionalized nanoparticles of TiO2, Fe2O3 and graphite were utilized to prepare polymer-nanostructure composites based on PVA and nylon-6,6. 相似文献
8.
《Journal of Experimental Nanoscience》2013,8(1):220-231
ABSTRACTWe successfully synthesised TiO2 nanotubes (TNTs) and silver nanoparticles (Ag NPs)-loaded TiO2 nanotubes paste. These were coated on a glass substrate by spin coating method, and their antibacterial activities were surveyed. The morphology of materials was defined by transmission electron microscopy (TEM) image; the crystalline structure and the composition of the materials were determined by X-ray diffraction (XRD) pattern and X-ray photoelectron spectroscopy (XPS). Vibrational properties of the molecules existing in the sample were investigated by Fourier transform infrared (FTIR) spectroscopy, and the transmittances of films were determined by UV–Vis transmittance spectroscopy. This research shows that the structure and morphology of TNTs did not change after they underwent the processes of paste preparing and film coating on a glass substrate. Furthermore, the transmittance of TNTs film (about 75%) is higher than Ag NPs-loaded TiO2 nanotubes (Ag/TNTs) film (about 65%) in the visible region. Moreover, the antibacterial property of Ag/TNTs film shows its effectiveness against Escherichia coli bacteria, and the antibacterial efficiency is 99.06% for 24 h-incubation period in the dark condition. 相似文献
9.
Dirk Oliver Schmidt Susanne Hoffmann‐Eifert Hehe Zhang Camilla La Torre Astrid Besmehn Michael Noyong Rainer Waser Ulrich Simon 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(48):6444-6456
Resistively switching devices are considered promising for next‐generation nonvolatile random‐access memories. Today, such memories are fabricated by means of “top–down approaches” applying thin films sandwiched between nanoscaled electrodes. In contrast, this work presents a “bottom–up approach” disclosing for the first time the resistive switching (RS) of individual TiO2 nanoparticles (NPs). The NPs, which have sizes of 80 and 350 nm, respectively, are obtained by wet chemical synthesis and thermally treated under oxidizing or vacuum conditions for crystallization, respectively. These NPs are deposited on a Pt/Ir bottom electrode and individual NPs are electrically characterized by means of a nanomanipulator system in situ, in a scanning electron microscope. While amorphous NPs and calcined NPs reveal no switching hysteresis, a very interesting behavior is found for the vacuum‐annealed, crystalline TiO2–x NPs. These NPs reveal forming‐free RS behavior, dominantly complementary switching (CS) and, to a small degree, bipolar switching (BS) characteristics. In contrast, similarly vacuum‐annealed TiO2 thin films grown by atomic layer deposition show standard BS behavior under the same conditions. The interesting CS behavior of the TiO2–x NPs is attributed to the formation of a core–shell‐like structure by re‐oxidation of the reduced NPs as a unique feature. 相似文献
10.
《Advanced Powder Technology》2020,31(12):4731-4742
Titania (TiO2) nanoparticles (NPs) with different morphologies (spherical, rod-shaped, and mixed) were prepared by hydrothermal treatment of different nitric acid (HNO3)/titanium (IV) isopropoxide (TTIP) molar ratios (0.25, 0.5, 1.0, and 1.7) at different hydrothermal temperatures (90, 150, 200, and 250 °C), hydrothermal times (6, 12, and 24 h), and calcination temperatures (500, 625, and 750 °C). The crystalline structure, morphology, and surface texture of the obtained TiO2 NPs were characterized by X-ray diffraction, nitrogen adsorption–desorption isotherm, field emission-scanning electron microscopy, and high resolution-transmission electron microscopy analyses. Under a larger HNO3: TTIP molar ratio, higher hydrothermal temperature, and higher hydrothermal time, the spherical mixed anatase–rutile phase TiO2 NPs were converted to a nanorod (NR)-shaped rutile phase (TiO2-R). The TiO2-R NRs gave the highest methanol conversion level (65%) and hydrogen yield (45%) in the oxidative steam reforming of methanol at 400 °C. 相似文献
11.
Dengyao Li Fuyi Chen Jian Liu 《Journal of Materials Science: Materials in Electronics》2013,24(8):2761-2766
Titanium dioxide (TiO2) layers were prepared by the pyrolysis of an ethanolic solution of di-iso-propoxy-titanium bis(acetylacetonate) in aerosol form, and then electrodeposited with Ag nanoparticles on their surface. The morphology and photoelectrochemical properties of the resulting Ag nanoparticles (NPs) on TiO2 films were found to be significantly tuned by varying the electrodeposition time in an aqueous electrolyte containing AgNO3 and KNO3. Photocurrent density–voltage curves and electrochemical impedance spectra revealed that the Ag NPs remarkably improved the short-circuit current density and open circuit voltage, and considerably reduced the electrochemical impedance. Therefore, Ag NPs deposition enhanced the photo-absorption of the TiO2 layer, excited photoelectrons by localised surface plasmon resonance, promoted photo-induced charge separation, and prevented electron–hole recombination. 相似文献
12.
《Journal of Experimental Nanoscience》2013,8(6):842-851
Using liquid phase deposition method on cellulose substrate, TiO2 nanofibres were prepared with TiCl4 as a precursor. TiO2 nanofibres were obtained after heat treatment of the cellulose template. The remaining product was composed of micron-size TiO2 fibres with a nanofiber microstructure. It is shown that nanofibres are formed through the aggregation of TiO2 nanoparticles. X-ray diffraction analysis of the as-prepared solution indicates the formation of crystalline TiO2 anatase phase. EDX analysis was employed to measure the adsorbed mass of TiO2 on cellulose substrate. The effect of deposition time on the growth and morphology was investigated by scanning electron microscopy. Transmission electron microscopy studies demonstrate fine microstructures composed of 10–15?nm?nanoparticles. Surface area of the TiO2 fibres, measured by Brunauer, Emmett and Teller analysis, was about 104?m2?g?1. Photodegradation of Rhodamine B as a standard dye shows that the prepared samples have a high photocatalytic activity due to large surface area. 相似文献
13.
Yu-Long Xie Peng-Cheng Lin Shu-Qing Hu Yong-Chang Lu Lei Li Hong Wang 《Journal of Materials Science: Materials in Electronics》2014,25(6):2665-2670
A ZnO nanorods (NRs)/TiO2 nanoparticles (NPs) film has been prepared by electrochemical deposition of ZnO NRs growth on P25 TiO2 NPs film surfaces. It was found that ZnO NRs/TiO2 NPs could significantly improve the efficiency of dye-sensitized solar cells owing to its relatively enhanced light-scattering capability and efficient charge transport efficiency. The overall energy-conversion efficiency (η) of 3.48 % was achieved by the formation of ZnO NRs/TiO2 NPs film, which is 33 % higher than that formed by TiO2 NPs alone (η = 2.62 %). The charge recombination behavior of cells was investigated by electrochemical impedance spectra, and the results showed that ZnO NRs/TiO2 NPs film has the longer electron lifetime than TiO2 NPs alone, which could facilitate the reduction of recombination processes and thus would promote the photocatalysis and solar cell performance. 相似文献
14.
Anna Wokovich Katherine Tyner William Doub Nakissa Sadrieh Lucinda F. Buhse 《Drug development and industrial pharmacy》2013,39(10):1180-1189
Background: There has been some apprehension expressed in the scientific literature that nanometer-sized titanium dioxide (TiO2) and other nanoparticles, if able to penetrate the skin, may cause cytotoxicity. In light of a lack of data regarding dermal penetration of titanium dioxide from sunscreen formulations, the Food and Drug Administration Center for Drug Evaluation and Research initiated a study in collaboration with the National Center for Toxicology Research using minipigs to determine whether nanoscale TiO2 in sunscreen products can penetrate intact skin. Four sunscreen products were manufactured. Method: The particle size distribution of three TiO2 raw materials, a sunscreen blank (no TiO2) and three sunscreen formulations containing uncoated nanometer-sized TiO2, coated nanometer-sized TiO2 or sub-micron TiO2 were analyzed using scanning electron microscopy (SEM), laser scanning confocal microscopy (LSCM), and X-ray diffraction (XRD) to determine whether the formulation process caused a change in the size distributions (e.g., agglomeration or deagglomeration) of the TiO2. Results: SEM and XRD of the formulated sunscreens containing nanometer TiO2 show the TiO2 particles to have the same size as that observed for the raw materials. This suggests that the formulation process did not affect the size or shape of the TiO2 particles. Conclusion: Because of the resolution limit of optical microscopy, nanoparticles could not be accurately sized using LSCM, which allows for detection but not sizing of the particles. LSCM allows observation of dispersion profiles throughout the sample; therefore, LSCM can be used to verify that results observed from SEM experiments are not solely surface effects. 相似文献
15.
Karathan Parakkandi Priyanka Variampally Sankar Harikumar Kagalagodu Manjunthiah Balakrishna Thomas Varghese 《IET nanobiotechnology / IET》2017,11(1):66
While nanoparticles (NPs) are known to exhibit antimicrobial properties, their effects on symbiotic arbuscular mycorrhizal fungi (AMF) in plant roots has to be carefully examined as NPs particularly of titanium dioxide (TiO2) reach plant roots through varied sources such as fertilisers, plant protection products and other nanoproducts. The objective of the present study is to assess the effect of TiO2 NPs on the symbiotic behaviour of AMF colonising rice (Oryza sativa L.) plants. Using sol–gel method, TiO2 NPs with three different sizes were successfully synthesised employing doping. Characterisation of the prepared material was done by X‐ray powder diffraction and scanning electron microscopy. The synthesised materials were applied at 0, 25, 50 and 100 mg plant–1 to the rhizosphere of mycorrhizal rice plants maintained in pots. The study revealed that the prepared NPs had an inhibitory effect on arbuscular mycorrhizal symbiosis in plant roots. Development of AMF structures such as vesicles and arbuscules was significantly reduced in TiO2 ‐doped NPs with a relatively more inhibition in 2% TiO2 ‐doped NPs. Among the concentrations of TiO2 NPs applied to different treatments, %F was significantly (P < 0.001) affected at medium to higher levels of application.Inspec keywords: nanoparticles, titanium compounds, antibacterial activity, sol‐gel processing, X‐ray diffraction, scanning electron microscopy, microorganisms, cellular biophysics, nanomedicineOther keywords: symbiotic arbuscular mycorrhizal fungi, plant roots, nanoparticles, antimicrobial properties, fertilisers, plant protection, nanoproducts, AMF colonising rice, sol‐gel method, X‐ray powder diffraction, scanning electron microscopy, mycorrhizal rice plants, rhizosphere, arbuscular mycorrhizal symbiosis, soil biota, TiO2 相似文献
16.
We demonstrate here a novel oxidative process to control the metallic bismuth (Bi°) nanoparticles (NPs) formation in bismuth glass nanocomposites by using KClO4 and KNO3 as oxidant instead of usual reducing technique. The formation of Bi° NPs has been monitored by its distinctive surface plasmon resonance (SPR) band at 460 nm in the UV–vis absorption spectra. It is further confirmed by the TEM images of Bi° NPs using KNO3 and KClO4 which show the formation of spherical Bi° NPs of 2–15 nm sizes and the SAED pattern reveals their crystalline rhombohedral phase. Using this technique it is possible to control the SPR band of nanobismuth (Bi°) in bismuth glasses. 相似文献
17.
Structural phase analysis,band gap tuning and fluorescence properties of Co doped TiO2 nanoparticles
This paper reports on structural and optical properties of Co (0, 3, 5 & 7 mol%) doped TiO2 (titania) nanoparticles (NPs) synthesized by employing acid modified sol–gel method. The crystalline phase of the pure and doped NPs was observed with X-ray diffraction (XRD) followed by Raman scattering technique. Field emission scanning electron microscope and transmission electron microscopy give the morphological details. Fourier transform infrared spectra indicate the bonding interactions of Co ions with the titania lattice framework. Optical studies were attained with UV–visible absorption and fluorescence emission spectroscopy. XRD analysis reveals that all prepared samples have pure anatase phase with tetragonal symmetry devoid of any other secondary phase. The average crystallite size of all samples was calculated using Scherrer’s formula and was found to vary from 8 to 10 nm with doping concentration of Co. The Raman spectroscopy further confirmed the formation of TiO2 in anatase structure in both pure and Co doped TiO2 NPs. The most intense Raman active Eg peak of TiO2 NPs shifted to higher energy on doping. Both UV–visible and fluorescence spectra show a blue shift in their absorption and band edge emission subsequently on increasing with Co percentage in titania host matrix, wherever there is an indication of quantum confinement effect with widening of band gap on decreasing in NPs size. There is also a possibility of strong Coulomb interaction effect on the optical processes involving the Co ions. However, the intensities of different emission spectra are not the same but decrease profoundly for doping samples due to concentration quenching effect. 相似文献
18.
《Journal of Experimental Nanoscience》2013,8(4):462-479
Nanocrystalline TiO2, Ag-doped TiO2 and TiO2–SBA-15 nanocomposites have been synthesised using a simple aqueous solution-based chemical method. Nanocrystalline TiO2 was synthesised by calcining the precursor prepared by using ethylenediamine tetraacetic acid and TiCl3 in aqueous medium. Formation of crystalline phase (anatase, rutile or mixed phase) and crystallite size were found to be dependent on calcination temperature. To enhance the photocatalytic activity, Ag-doped TiO2 was synthesised by doping of Ag during the synthesis step of TiO2. TiO2–SBA-15 nanocomposites were synthesised by impregnation method. Pure anatase TiO2 nanoparticle was formed in the amorphous matrix of the silicate SBA-15, even though the loading of the TiO2 in the silicate matrix was as low as 5?wt%. The synthesised materials were characterised using thermal analysis, powder X-ray diffraction method, surface area and porosimetry analysis, diffuse reflectance analysis and transmission electron microscopy. The photocatalytic property of the synthesised materials was investigated towards the degradation of methyl orange under sunlight exposure and monitored by UV–visible spectrophotometer. Ag-doped TiO2 exhibited enhanced photocatalytic activity than undoped TiO2. TiO2–SBA-15 nanocomposites showed impressive photocatalytic activity even with 10?wt% TiO2 loading. 相似文献
19.
Newaz Mohammed Bahadur Masahide Sato Fumio Kurayama 《Materials Research Bulletin》2010,45(10):1383-187
A novel and rapid microwave method was used to prepare TiO2 coated ZnO nanocomposite particles. The resulted particles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). Results show that ZnO nanoparticles were coated with 6-10 nm amorphous TiO2 layers. In addition, zeta potential analysis demonstrated the presence of TiO2 layer on the surface of ZnO nanoparticles. Photoluminescence (PL) spectroscopy and UV-visible spectroscopy were used to investigate the optical properties of the nanoparticles. Compared to uncoated ZnO nanoparticles, the TiO2 coated ZnO nanoparticles showed enhanced UV emission. The UV-visible diffuse reflectance study revealed the significant UV shielding characteristics of the nanocomposite particles. Moreover, amorphous TiO2 coating effectively reduced the photocatalytic activity of ZnO nanoparticles as evidenced by the photodegradation of Orange G with uncoated and TiO2 coated ZnO nanoparticles under UV radiation. 相似文献
20.
Priya Kalia Gema Vizcay-Barrena Jian Ping Fan Alice Warley Lucy Di Silvio Jie Huang 《Journal of the Royal Society Interface》2014,11(93)
Bone cells (osteoblasts) produce a collagen-rich matrix called osteoid, which is mineralized extracellularly by nanosized calcium phosphate (CaP). Synthetically produced CaP nanoparticles (NPs) have great potential for clinical application. However few studies have compared the effect of CaP NPs with different properties, such as shape and aspect ratio, on the survival and behaviour of active bone-producing cells, such as primary human osteoblasts (HOBs). This study aimed to investigate the biocompatibility and ultrastructural effects of two differently shaped hydroxyapatite [Ca10(PO4)6(OH)2] nanoparticles (HA NPs), round- (aspect ratio 2.12, AR2) and rice-shaped (aspect ratio 3.79, AR4). The ultrastructural response and initial extracellular matrix (ECM) formation of HOBs to HA NPs were observed, as well as matrix vesicle release. A transmission electron microscopy (TEM)-based X-ray microanalytical technique was used to measure cytoplasmic ion levels, including calcium (Ca), phosphorus (P), sodium (Na) and potassium (K). K/Na ratios were used as a measure of cell viability. Following HA NP stimulation, all measured cytoplasmic ion levels increased. AR2 NPs had a greater osteogenic effect on osteoblasts compared with AR4 NPs, including alkaline phosphatase activity and matrix vesicle release. However, they produced only a moderate increase in intracellular Ca and P levels compared with AR4. This suggests that particular Ca and P concentrations may be required for, or indicative of, optimal osteoblast activity. Cell viability, as measured by Na and K microanalysis, was best maintained in AR2. Initial formation of osteoblast ECM was altered in the presence of either HA NP, and immuno-TEM identified fibronectin and matrilin-3 as two ECM proteins affected. Matrilin-3 is here described for the first time as being expressed by cultured osteoblasts. In summary, this novel and in-depth study has demonstrated that HA NP shape can influence a range of different parameters related to osteoblast viability and activity. 相似文献