共查询到20条相似文献,搜索用时 15 毫秒
1.
Abdelkader Nebatti Christian Pflitsch Christopher Eckert Burak Atakan 《Progress in Organic Coatings》2010
A relatively new promising method for surface temperature measurement is the use of thermographic phosphors. For this application, the temperature-dependent luminescence properties of europium (III)-doped anatase (TiO2:Eu3+) thin films were studied. The films were prepared by the sol–gel method using dip coating. The structures and the morphology of the films were determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Electron dispersive X-ray spectroscopy (EDX) was used to verify the europium concentration within the films. For using the films as temperature sensors the optical properties are the main concern. Therefore, the emission spectra of the films were measured after ultraviolet laser excitation (355 nm). They indicate that the red characteristic emission (617 nm) of TiO2:Eu3+ due to the 5D0 → 7F2 electric dipole transition is the strongest. The decay time constant of the exponential emission decay under UV excitation with a Nd:YAG laser (355 nm, f = 10 Hz) is strongly temperature dependent in the range from 200 °C up to 400 °C; making it useful for temperature evaluation. The temperature dependence was measured for the emission line at 617 nm; the results demonstrate that anatase doped europium (III) can be used as a thermographic phosphor. 相似文献
2.
《Ceramics International》2016,42(6):7014-7022
Highly ordered TiO2 and WO3–TiO2 nanotubes were prepared by one-step electrochemical anodizing method and cobalt has been successfully deposited on these nanotubes by photo-assisted deposition process. The morphology, crystal structure, elemental composition and light absorption capability of samples were characterized by field emission scanning electron microscope, X-ray diffraction, energy dispersive X-ray spectrometer and ultraviolet–visible spectroscopy methods. All cobalt loaded samples show an appearance of red shift relative to the unloaded samples. The degradation of methylene blue was used as a model reaction to evaluate the photocatalytic activity of these novel visible-light-responsive photocatalysts. Results showed that the photocatalytic activity of bare WO3–TiO2 samples is higher than that with undoped TiO2 sample. Compared with unmodified TiO2 and WO3–TiO2, the Co/TiO2 and Co/WO3–TiO2 samples exhibited enhanced photocatalytic activity in the degradation of methylene blue. Kinetic research showed that the reaction rate constant of Co/WO3–TiO2 is approximately 2.26 times higher than the apparent reaction rate constant of bare WO3–TiO2. This work provides an insight into designing and synthesizing new TiO2–WO3 nanotubes-based hybrid materials for effective visible light-activated photocatalysis. The catalysts prepared in this study exhibit industrially relevant interests due to the low cost and high photocatalytic activity. 相似文献
3.
SiO32? doped TiO2 films with oriented nanoneedle and nanorectangle block structure has been firstly synthesized by hydrothermal synthesis method. The prepared samples are characterized, X-ray diffraction (XRD) results demonstrate that the SiO32? doped TiO2 films are rutile and brookite phases. The scanning electron microscope (SEM) analysis reveals that the quantity of O2 affects the morphology of the SiO32? doped TiO2 films (SiTiA films prepared with unmodified substrate). The SiO32? doped TiO2 films (SiTiB films prepared with modified substrate) display two layers, one is porous structure, the other is nanoneedle structure. UV–vis, IR, transmission electron microscopy (TEM) and energy-dispersive X-ray (EDX) microscopy all prove that SiO32? have been doped in the TiO2 crystal structure. They have remarkable red shift and higher photocatalytic activity of degradation of methylene blue than P-25 under visible light (λ > 420 nm) irradiation. Besides, photocatalytic activity of the film is stable during 4 times recycling. 相似文献
4.
Great efforts have been made to develop efficient visible light-activated photocatalysts in recent years. In this work, a new nanocomposite consisting of anatase TiO(2), Ag, and graphene was prepared for use as a visible light-activated photocatalyst, which exhibited significantly increased visible light absorption and improved photocatalytic activity, compared with Ag/TiO(2) and TiO(2)/graphene nanocomposites. The increased absorption in visible light region is originated from the strong interaction between TiO(2) nanoparticles and graphene, as well as the surface plasmon resonance effect of Ag nanoparticles that are mainly adsorbed on the surface of TiO(2) nanoparticles. The highly efficient photocatalytic activity is associated with the strong adsorption ability of graphene for aromatic dye molecules, fast photogenerated charge separation due to the formation of Schottky junction between TiO(2) and Ag nanoparticles and the high electron mobility of graphene sheets, as well as the broad absorption in the visible light region. This work suggests that the combination of the excellent electrical properties of graphene and the surface plasmon resonance effect of noble metallic nanoparticles provides a versatile strategy for the synthesis of novel and efficient visible light-activated photocatalysts. 相似文献
5.
Anna Sobczyk-Guzenda Bożena PietrzykHieronim Szymanowski Maciej Gazicki-LipmanWitold Jakubowski 《Ceramics International》2013
Thin titanium dioxide films, deposited using RF PECVD and sol–gel techniques, were studied comparatively with respect to their bactericidal as well as self-cleaning properties. The effect of the deposition process on film morphology, chemical and crystalline structure, bactericidal activity and hydrophilic properties was investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), surface profilometry, optical microscopy and contact angle measurements. It was found that the bactericidal activity of amorphous TiO2 films, produced using the RF PECVD method, as either comparable to or better than those of crystalline (anatase) films deposited by means of the sol–gel technique. One reason for such advantageous behavior of plasma deposited materials is thought to be their substantially higher surface roughness, as revealed by AFM measurements. The hydrophilic effect, induced with UV irradiation, was strongest in the case of sol–gel films, but the RF PECVD synthesized coatings were found to be only slightly less hydrophilic. The conclusion follows that both sol–gel and RF PECVD techniques are equally capable of producing titanium dioxide films of high photocatalytic quality. 相似文献
6.
《Ceramics International》2016,42(16):18257-18263
Novel photocatalysts based on silver (Ag), TiO2, and graphene were successfully synthesized by microwave-assisted hydrothermal method. The prepared photocatalysts were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) specific surface area analysis, X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). The influence of silver loading and graphene incorporation on photocatalytic hydrogen (H2) production of as-prepared samples was investigated in methanolic aqueous solution under visible light irradiation (λ≥420 nm). The results showed that Ag–TiO2/graphene composite had appreciably enhanced photocatalytic H2 production performance under visible light illumination compared to pure TiO2, Ag–TiO2 and TiO2/graphene samples. The enhanced photocatalytic hydrogen production activity of Ag–TiO2/graphene composite under visible light irradiation could be attributed to increased visible light absorption, reduced recombination of photogenerated charge carriers and high specific surface area. This novel study provides more insight for the development of novel visible light responsive TiO2− graphene based photocatalysts for energy applications. 相似文献
7.
Ag–TiO2 nanocatalyst, supported on multi-walled carbon nanotubes, was synthesized successfully via a modified sol–gel method, and the prepared photocatalyst was used to remediate aqueous thiophene environmentally by photocatalytic oxidation under visible light. The prepared Ag–TiO2/multi-walled carbon nanotubes nanocomposite photocatalyst was characterized through X-ray diffraction, Brunauer–Emmett–Teller (BET), transmission electron microscopy, and UV–vis spectra (UV–vis). The results showed that both Ag and TiO2 nanoparticles were well-dispersed over the MWCNTs and formed a uniform nanocomposite. Ag doping can eliminate the recombination of electron–hole pairs in the catalyst, and the presence of MWCNTs in the TiO2 composite can change surface properties to achieve sensitivity to visible light. The optimum mass ratio of MWCNT:TiO2:Ag was 0.02:1.0:0.05, which resulted in the photocatalyst's experimental performance in oxidizing about 100% of the thiophene in a 600 mg/L solution within 30 min and with 1.4 g L−1 amount of catalyst used. 相似文献
8.
Optical and photoelectrochemical (PEC) properties of a TiO2 thin film electrode doped with a new variation of ruthenium–(4,4′dimethyl-2,2′-bipyridine)–isothiocyanato–tungsten[bis-(phenyl-1,2-ethilenodithiolenic)] bimetallic complex (BM) were investigated. Physical adsorption process was used to immobilise the BM on the TiO2 thin film. Crystalline structure and surface morphology of the thin films were examined using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy-dispersive X-ray (EDX) techniques. N3 commercial dye was also used as a dopant to the TiO2 films for comparison. Light absorption spectra and bandgap energy of the thin films were determined using UV–vis spectroscopy. Light absorption of the TiO2 thin film doped with BM was better than the TiO2 doped with the N3 commercial dye. Band edges of the TiO2 thin film and the BM were determined via cyclic voltammetry (CV) measurements. Top-edge of the BM valence band (VB) was more positive than the bottom edge of the conduction band (CB) of the TiO2 film (vs. NHE). PEC analysis indicated that photocurrent of TiO2 doped with the BM electrode was higher than TiO2 doped with the N3 in the beginning of illumination process, but the performance was defeated after a while. Based on the optical properties and the PEC analyses, BM has potential to be used as dye sensitisers for a PEC cell. 相似文献
9.
YoonKeun Chae JinWon Park Shinsuke Mori Masaaki Suzuki 《Korean Journal of Chemical Engineering》2013,30(1):62-66
The photocatalytic characteristics of partially reduced TiO2 (TiO2?x ) by plasma treatment and plasma-heated treatment were investigated in the visible-light region. For the visible-light photocatalytic activity of TiO2?x , plasmaheated treatment shows stronger than plasma treatment significantly. The TiO2?x by plasma-heated treatment shows broader red-shifted absorption bands than one by plasma treatment in the visible-light region. The surface color of TiO2?x by plasma treatment and plasma-heated treatment changed from white to sky blue, and to navy, respectively. After exposure to air, the surface color of TiO2?x changed from sky blue to white for plasma treatment and from navy to beige for plasma-heated treatment. 相似文献
10.
Photocatalytic behavior of TiO_2 and ZnO prepared with different methods under ultraviolet and visible light irradiation 总被引:1,自引:0,他引:1
IntroductionIn recent years photocatalytic oxidation hasreceived considerable attention as an alternativeremediation technology since the method offers anumber of advantages over conventionaltechnologies [1,2] Elimination o… 相似文献
11.
《Ceramics International》2016,42(9):11184-11192
Transition metal oxide (Fe2O3, Co3O4 and CuO) loaded ZnTiO3–TiO2 nanocomposites were successfully prepared by solid state dispersion method. The structural, morphological and optical properties of samples were characterized by TGA/DTA, XRD, BET, FT-IR, DRS, PL, XPS and SEM techniques. The photocatalytic activity of samples was investigated by degradation of 4-chlorophenol in water under sunlight. The Fe2O3 loaded sample was found to exhibit much higher photocatalytic activity than the other composite powders. 7Fe2O3/ZnTi sample has the highest percentage of 4-chlorophenol degradation (100%) and highest reaction rate (1.27 mg L−1 min−1) was obtained in 45 min. The enhancement of photocatalytic activity for ZnTiO3–TiO2 sample with Fe2O3 addition may be attributed to its small particle size, the presence of more surface OH groups, lower band gap energy than other samples in this paper and the presence of more hexagonal ZnTiO3 phase in the morphology. 相似文献
12.
TiO2 porous ceramic/Ag–AgCl composite was prepared by incorporating AgCl nanoparticles within the bulk of TiO2 porous ceramic followed by reducing Ag+ in the AgCl particles to Ag0 species under visible light irradiation. The porous TiO2 ceramic was physically robust and chemically durable, and the porous structure facilitated the implantation of AgCl NPs. Compared with the bare TiO2 ceramic, TiO2 porous ceramic/Ag–AgCl composite exhibited higher photocatalytic performance for the degradation of MO and RhB under visible light irradiation. The reaction rate constants k of MO and RhB degradation over TiO2 porous ceramic/Ag–AgCl composite was respectively 6.25 times and 3.62 times higher than those recorded over the bare TiO2 porous ceramic. The photocatalytic activity showed virtually no decline after four times cyclic experiments under visible light irradiation. Scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, UV–Vis diffuse reflectance spectroscopy, photoluminescence spectra and X-ray photoelectron spectroscopy were used to characterize the TiO2 porous ceramic/Ag–AgCl composite. 相似文献
13.
Kais Elghniji Mohamed Ksibi Elimame Elaloui 《Journal of Industrial and Engineering Chemistry》2012,18(1):178-182
A series of N-substituted titanium (IV) 2-ethyl-1,3-hexanediolate Ti(C32H68O8) precursor were synthesized by the sol–gel reverse micelle (SGRM) method. The ethylene diaminetetraacetic acid (Na2EDTA) has been used as a source of nitrogen n species. The obtained solids were calcined at 500 ?C for 1 h to obtain photoactive phases. The effect of nitrogen content (N/Ti = 0.025; 0.03; 0.05 atomic ratios) is examined. The materials were characterized by XRD, BET, TG/DTA and UV–vis reflectance spectroscopy (DRS). Photocatalytic decolourisation of methylen blue (MB) in aqueous solution was carried out using nano, doped TiO2. Experimental results revealed that N/Ti = 0.05 atomic ratio N-doped TiO2 required shorter irradiation time for complete decolourisation of MB than pure nano TiO2 and commercial (Degussa P-25) TiO2. 相似文献
14.
Masato Takeuchi Hiromi Yamashita Masaya Matsuoka Masakazu Anpo Takashi Hirao Nobuhisa Itoh Nobuya Iwamoto 《Catalysis Letters》2000,67(2-4):135-137
Transparent TiO2 thin film photocatalysts were prepared on transparent porous Vycor glass (PVG) by the ionized cluster beam (ICB) method.
In order to improve the photocatalytic performance of these thin films under visible light irradiation, transition metal ions
such as Cr and V were implanted into the deep bulk inside of the films using an advanced metal‐ion‐implantation technique.
The UV‐vis absorption spectra of these metal‐ion‐implanted TiO2 thin films were found to shift smoothly toward visible light regions, its extent depending on the amount and kinds of metal
ions implanted. Using these metal‐ion‐implanted TiO2 thin films as photocatalysts, the photocatalytic decomposition of NOx into N2 and O2 was successfully carried out under visible light (λ 450 nm) irradiation at 275 K.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
15.
Robust visible-light Gd–La codoped TiO2 nanotubes were successfully synthesized via an ultrasonic hydrothermal method and the photocatalytic activities were evaluated by photodegrading Rhodamine B (RB). The calcined Gd–La codoped TiO2 nanotubes have significantly enhanced photocatalytic activities than the uncalcined ones. The La3+ and Gd3+ in the lattices of rare earth oxides may be substituted by Ti4+, creating abundant oxygen vacancies and surface defects for electron trapping and dye adsorption, accelerating the separation of photogenerated electron–hole pairs and RB photodegradation. The formation of an excitation energy level below the conduction band of TiO2 from the binding of electrons and oxygen vacancies decreases the excitation energy of Gd–La codoped TiO2 nanotubes, resulting in robust photocatalysts. The results suggest that Gd–La codoped TiO2 nanotubes calcined at 500 °C are very promising for enhancing the photocatalytic activity of photocatalysts in visible-light region. 相似文献
16.
The preparation of the TiO2, ZnO, and TiO2/ZnO nanofilms was conducted on glass via sol–gel process. The prepared film was detailedly characterized by means of OM, SEM, XRD, and EDS. The results showed that the obtained pure TiO2 was composed of nanoparticles. For pure ZnO it consisted of nanoparticles and large agglomerates. Both the microstructural morphology and the crystallization of the prepared TiO2/ZnO composite film were strongly related to the Ti/Zn ratio in the film. With a Ti/Zn ratio less than 1/1, the composite film was absence of cracks. Poor crystallization was definitely observed for the composite film with Ti/Zn ratio of 3/1 and 1/1. The EDS analysis revealed homogeneous distribution of Ti and Zn elements in the film. 相似文献
17.
Nanocrystalline Fe2TiO5 thin films have been grown on Si (1 0 0) at room temperature by using simple, cost effective sol–gel process assisted by microwave irradiation for thermal treatment. For comparison purpose the deposited films have been subjected to two kinds of annealing treatments: first set by using conventional annealing and second set by irradiating the deposited films at different microwave powers for 10 min. In both treated films, formation of orthorhombic phase of Fe2TiO5 structure has been observed. It is evident that there is a dramatic structural modification when the deposited films are exposed to microwave. There was slight stoichiometric change of Fe2TiO5 thin films treated by conventional annealing and microwave annealing. Microwave exposed films have shown 47% of Fe, 6% of Ti and 47% of O in the films of the Fe2TiO5, whereas annealed films have shown close to the stoichiometry in Fe2TiO5 with 30% of Fe, 14% of Ti and 56% of O. Plausible mechanism for the formation of nanocrystalline orthorhombic phase of Fe2TiO5 perovskite structure at low microwave powers has also been discussed. This new innovative microwave heating could open a door for the advanced nanotechnologies to cut down the process cost in post treatment of the nanomaterials. 相似文献
18.
Mélisa Hatat-Fraile Julie MendretMatthieu Rivallin Stephan Brosillon 《Chemical Engineering Research and Design》2013
In this study, the role of mixing hydrodynamics during the sol–gel synthesis of titania nanoparticles and the consequences on their photocatalytic properties were investigated. For the first time three different T-mixer geometries were tested. Alcoholic solutions of titanium tetra-isopropoxide and water were mixed in three different T-mixers with turbulence promoters and thus different mixing characteristics. The changes of nanoparticle sizes during the induction time of the sol–gel process were followed by dynamic light scattering and velocity and turbulence fields were simulated by Computational Fluid Dynamics (CFD) for the three T-mixer geometries. The results indicated that macro-mixing is crucial during the first step as it determines the nucleation rate and then the primary particle size. The micro-mixing has an influence on particle properties, especially on particle stability. Titanium dioxide nanoparticles synthesized by the sol–gel process were deposited on alumina supports. A homogeneous film of about 200 nm was deposited in all cases. Degradation of Acid Orange 7 (AO7) was used to evaluate the photocatalytic activity of TiO2 coatings. No difference was observed between the photoactivity of synthesized TiO2. Total mineralization of the dye occurred after 24 h irradiation. 相似文献
19.
In this work, a set of SiO2–TiO2 mixed oxides was prepared by the polymeric sol–gel route and deposited on glass substrate through the dip coating technique. Then, the effect of different important preparation parameters (sol–gel stabilizers, Ti content, and heat treatment) on the phase separation was investigated. The developed films were heat treated at 500 °C and characterized using TGA/DTA, FTIR, XRD, SEM, and AFM. The results showed that TiO2 segregation can be controlled by selecting an appropriate composition of diethanolamine (DEA) and methyl methacrylate (MMA) for preparation of polymeric silica–titania sol. Besides, anatase phase in the samples were crystallized without any stabilizers within heat treatment procedure at 500 °C; however, using appropriate composition of DEA and MMA crystallization rate significantly decreased. 相似文献
20.
Yidong Hou 《Powder Technology》2010,203(3):440-160
Nanostructured β-Ga2O3 samples were prepared by a combination of the solvothermal processes and subsequent heat treatments. β-Ga2O3 samples with various morphologies were obtained by using different kinds of solvent, including water, isopropanol and ethylene glycol. One-dimensional β-Ga2O3 nanorods were obtained in water medium, while β-Ga2O3 spheres were prepared in alcohol. The possible mechanism related to the phase formation and morphology of the as-prepared materials was discussed. Photocatalytic performance of the synthesized β-Ga2O3 samples was also examined. Results revealed that β-Ga2O3 sample prepared with ethylene glycol showed the highest photocatalytic activity for the degradation of salicylic acid. This could be ascribed to the high surface area, abundant hydroxyl groups, and wide band gap of β-Ga2O3 sample synthesized in ethylene glycol. 相似文献