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1.
Four new copper(II) porphyrins CuPp(1, 2, 3, 4) with a different number of peripheral ester groups were synthesized and used to sensitize the mesoporous TiO 2 under solvothermal condition, and accordingly, four mesoporous CuPp(1, 2, 3, 4)/TiO 2 composites were obtained. These composites were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, BET nitrogen adsorption–desorption isotherms (BET), UV–vis diffuse reflectance spectroscopy (UV–vis-DRS), and Fourier-transform infrared spectroscopy (FT-IR). The results showed the crystal structure and morphology of mesoporous TiO 2 were not affected by the porphyrin existence on its surface. The photocatalysis properties of mesoporous TiO 2 and CuPp(1, 2, 3, 4)/TiO 2 have been evaluated by conducting the photocatalytic degradation of 4-nitrophenol (4-NP) under visible-light irradiation, and the result showed their higher photocatalytic activities and the order is: CuPp(4)/TiO 2 > CuPp(3)/TiO 2 > CuPp(2)/TiO 2 > CuPp(1)/TiO 2 ? TiO 2. The probable reasons are their large surface area and different number of peripheral groups in CuPp, which separate electron–hole pairs efficiently. The repetition test of CuPp(1, 2, 3, 4)/TiO 2 composites demonstrated that they still maintained superior photocatalytic activity over six recycles. 相似文献
2.
C, N codoped TiO 2 catalyst has been synthesized by thermal decomposition of a novel water-soluble titanium complex. The structure, morphology, and optical properties of the synthesized TiO 2 catalyst were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and UV–vis diffuse reflectance spectroscopy. The photocatalytic activity of the Pt deposited TiO 2 catalysts synthesized at different temperatures was evaluated by means of hydrogen evolution reaction under both UV–vis and visible light irradiation. The investigation results reveal that the photocatalytic H 2 evolution rate strongly depended on the crystalline grain size as well as specific surface area of the synthesized catalyst. Our studies successfully demonstrate a simple method for the synthesis of visible-light responsive Pt deposited TiO 2 catalyst for solar hydrogen production. 相似文献
3.
The CuBi 2O 4/TiO 2 p–n heterojunction composites were obtained by in situ sol–gel coating process using prepared CuBi 2O 4 powders and titania colloid. The obtained CuBi 2O 4/TiO 2 composites were characterized by XRD, SEM, BET and UV–vis diffuse reflectance spectroscopy. Their photocatalytic and adsorption activities were evaluated by degradations and adsorptions of methyl orange and congo red. Results showed that some compositions of prepared p–n heterojunction composites exhibited much higher photocatalytic activity and absorption performance than pure CuBi 2O 4 or pure TiO 2, demonstrating that the formation of p–n heterojunction between the two materials plays an important role in improving photocatalytic activity and adsorption performance. 相似文献
4.
Composites of poly (N-isopropylacrylamide-co-acrylic acid)/titanium dioxide (TiO 2) have been prepared via UV-initiated free radical polymerization. Fourier transform infrared spectra (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), environmental scanning electron microscope (ESEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) are used to study the composition, structure, and morphology of the as-prepared composites. TiO 2 is found to be successfully encapsulated in the copolymer in spherical shapes with size of 2.5 μm. The thermo- and pH-responsive properties of the composites are observed using dynamic light scattering (DLS). The photocatalytic property of the composites is studied using UV–vis spectrophotometer on the degradation of methyl orange (MO) solution under various pHs and temperatures. Degradation ratio is higher at low pH and increases with increasing temperature above volume phase transition temperature (VPTT). 相似文献
5.
TiO 2–graphene oxide nanocomposites have been fabricated by the sol–gel technique for degradation of a typical cationic dye solution. The prepared photocatalysts were characterized by X‐ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric‐differential analyses, Brunauer–Emmett–Teller surface area measurement, and scanning and transmission electron microscopy. In addition, the photocatalytic activities of samples were evaluated by degradation of methylene blue aqueous solution under the sunlight irradiation. The change in color of solution was evaluated by the UV–vis spectroscopy, and the maximum photocatalytic decoloration (94%) was achieved within 60 min, which exceeded that of pure anatase under the same conditions. The results show that the nanocomposite containing 9.0 wt% of graphene oxide has the superior photocatalytic performance to either single‐phase anatase or other composites containing different amounts of graphene oxide. The experimental degradation data obtained from the batch tests were analyzed by a modified kinetic model, which predicted the performance with higher regression coefficients and lower relative errors. The distribution of TiO 2 nanoparticles (<20 nm) on graphene oxide sheets is proposed to be the efficient factor in the homogeneous degradation of dye which can concomitantly improve the photocatalytic activity. 相似文献
6.
In this study, novel ternary Fe 2O 3/ZnO/ZnFe 2O 4 (ZFO) composites were successfully prepared through a simple hydrothermal reaction with subsequent thermal treatment. The as-prepared products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) analysis, Barrett-Joyner-Halenda (BJH) measurement, and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). The photocatalytic degradation of rhodamine B (Rh B) under visible light irradiation indicated that the ZFO composites calcined at 500 °C has the best photocatalytic activity (the photocatalytic degradation efficiency can reach up to 95.7% within 60 min) and can maintain a stable photocatalytic degradation efficiency for at least three cycles. In addition, the photocatalytic activity of ZFO composites toward dye decomposition follows the order cationic Rh B > anionic methyl orange. Finally, using different scavengers, superoxide and hydroxyl radicals were identified as the primary active species during the degradation reaction of Rh B. 相似文献
7.
This study was focused on the photocatalytic activity of polyaniline (Pani)/iron doped titanium dioxide (Fe–TiO 2) composites for the degradation of methylene blue as a model dye. TiO 2 nanoparticles were doped with iron ions (Fe) using the wet impregnation method and the doped nanoparticles were further combined with Pani via an in situ polymerization method. For comparison purposes, Pani composites were also synthesized in the presence undoped TiO 2. The photocatalyst and the composites were characterized by standard analytical techniques such as FTIR, XRD, SEM, EDX and UV–Vis spectroscopies. Fe–TiO 2 and its composites exhibited enhanced photocatalytic activity under ultraviolet light irradiation. Improved photocatalytic activity of Fe–TiO 2 was attributed to the dopant Fe ions hindering the recombination of the photoinduced charge carriers. Pani/Fe–TiO 2 composite with 30?wt.% of TiO 2 nanoparticles achieved 28% dye removal and the discoloration rate of methylene blue for the sample was 0.0025?min ?1. FTIR, XRD, SEM, EDX and UV–Vis spectroscopies supported the idea that Fe ions integrated into TiO 2 crystal structure and Pani composites were successfully synthesized in the presence of the photocatalyst nanoparticles. The novelty of this study was to investigate the photocatalytic activity of Pani composites, containing iron doped TiO 2 and to compare their results with that of Pani/TiO 2. 相似文献
8.
ZnFe 2O 4 nanoparticles sensitized by C-modified TiO 2 hybrids (ZnFe 2O 4–TiO 2/C) were successfully prepared by a feasible method. The ZnFe 2O 4 nanoparticles were prepared by mechanical alloying and annealing. The residual organic compounds in the synthetic process of TiO 2 were selected as the carbon source. The as-prepared composites were characterized by X-ray diffraction, Raman spectroscopy, X-ray fluorescence, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet–visible light diffuse reflectance spectroscopy (UV–Vis) and N 2 adsorption–desorption analysis. The photocatalytic activity of the photocatalysts was measured by degradation of methyl orange under ultraviolet (UV) light and simulated solar irradiation, respectively. The results show that the carbon did not enter the TiO 2 lattice but adhered to the surface of TiO 2. The photocatalytic activity of the as-prepared C-modified TiO 2 (TiO 2/C) improved both under UV and simulated solar light irradiation, but the improvement was not dramatic. Introduction of ZnFe 2O 4 into the TiO 2/C could enhance the absorption spectrum range. The ZnFe 2O 4–TiO 2/C hybrids exhibited a higher photocatalytic activity both than that of the pure TiO 2 and TiO 2/C under either UV or simulated solar light irradiation. The complex synergistic effect plays an important role in improving the photocatalytic performance of ZnFe 2O 4–TiO 2/C composites. The optimum photocatalytic performance was obtained from the ZnFe 2O 4(0.8 wt%)–TiO 2/C sample. 相似文献
9.
In this paper, magnetic nanocomposites are synthesized by loading reduced graphene oxide (RG) with two components of nanoparticles consisting of titanium dioxide (TiO 2) and magnetite (Fe 3O 4) with varying amounts. The structural and magnetic features of the prepared composite photocatalysts were investigated by powder X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectra (UV–vis/DRS), Raman and vibrating sample magnetometer (VSM). The resulting TiO 2/magnetite reduced graphene oxide (MRGT) composite demonstrated intrinsic visible light photocatalytic activity, on degradation of tartrazine (TZ) dye from a synthetic aqueous solution. Specifically, it exhibits higher photocatalytic activity than magnetite reduced graphene oxide (MRG) and TiO 2 nanoparticles. The photocatalytic degradation of TZ dye when using MRG and TiO 2 for 3 h under visible light was 35% and 10% respectively, whereas for MRGT it was more than 95%. The higher photocatalytic efficiency of MRGT is due to the existence of reduced graphene oxide and magnetite which enhances the photocatalytic efficiency of the composite in visible light towards the degradation of harmful soluble azo dye (tartrazine). 相似文献
10.
ABSTRACTPolymer nanocomposites are already a part of many important worldwide businesses. Among many nanocomposite precursors, titanium dioxide (TiO 2) nanopowder is increasingly being investigated due to its special properties. In this work, the feasibility of synthesising a new series of materials, copoly(arylidene-ether)/titanium dioxide nanocomposites, using in-situ copolymerisation technique has been investigated. This can be performed by the interaction of both cyclohexanone and 4- tert-butylcyclohexanone monomers with 4,4′-diformyl-2,2′-dimethoxy- α,ω-diphenoxyalkanes Ia–e, respectively, using different additions of titanium dioxide-P25. The structure of the prepared nanocomposites IIa–e/TiO 2 (0.2–3.0%) was confirmed by elemental analysis (energy dispersive X-ray spectroscopy) and spectral data (Fourier transform-infrared [FT-IR]). FT-IR verified the dispersion of nanofillers in the copolymer. Then, the characterisation and applications of these nanocomposites are extensively discussed depending on the investigation of how the addition of titanium dioxide nanoparticles affected on their properties using various techniques, such as X-ray diffraction, SEM, transmission electron microscopy, Water Contact Angle (WCA), thermogravimetric analysis, differential thermogravimetric, differential thermal analysis (DTA), polarising optical microscope and UV–vis absorption spectroscopy. The nanoparticles affected on the copolymer thermal behaviour in different ways (discrepancy results) depending on how these nanoparticles are dispersed in the copolymer matrix. UV–vis absorption spectra displayed a decrease in the optical band gap of some nanocomposites, which resulted from the addition of titanium dioxide to these copolymers, and this can improve the efficiency of them as organic emitting materials. 相似文献
11.
The nanocomposites of titania coupled with graphene oxide (GO) and reduced graphene oxide (rGO), respectively, were prepared by homogeneous hydrolysis with urea. Graphene was obtained by effect of high‐intensity cavitation field on natural graphite in the presence of strong aprotic solvents in pressurized ultrasonic reactor. The morphology of TiO 2–GO and TiO 2–rGO composites was assessed by scanning electron microscopy and atomic force microscopy. The nitrogen adsorption–desorption was used for determination of surface area (BET) and porosity. Raman and IR spectroscopy were used for qualitative analysis and diffuse reflectance spectroscopy was employed to estimate band‐gap energies. Further enhancement of the photocatalytic activity was attained by codoping of composites with noble metals—Au, Pd and Pt. The photocatalytic activity of TiO 2–GO and TiO 2–rGO were assessed by photocatalytic decomposition of Orange II dye in an aqueous slurry under UV and visible light irradiation. The photocatalytic activity of noble metals codoped samples was determined with decomposition of Reactive Black 5 azo dye. 相似文献
12.
Au–TiO 2/bentonite samples were prepared via deposition–precipitation method and calcined at different temperatures. These samples were characterized by X-ray diffraction (XRD), UV–vis diffusion reflectance spectroscopy (DRS), BET method, X-ray photoelectron spectroscopy (XPS) and TEM. The photocatalytic activities of the samples were tested by photodegradation of sulforhodamine B (SRB) under ultraviolet (UV) and visible light irradiation. The result showed that Au–TiO 2/bentonite catalysts exhibited higher efficiency for mineralizing SRB than the well-known commercial TiO 2 photocatalyst P25 in terms of COD changes. The most important advantage of Au–TiO 2/bentonite over P25 was that it could be readily separated from aqueous suspensions by sedimentation after the reaction. It can maintain almost the same activity after being repeatedly used for 12 times. Possible mechanisms for SRB photoreaction in the presence of Au–TiO 2/bentonite were proposed in this paper. 相似文献
13.
Cerium‐doped titanium dioxide (TiO 2) with a hollow fiber structure was successfully prepared using ammonium ceric nitrate and tetrabutyltitanate as precursors and cotton fiber as the template. The effects of cerium (Ce)‐doping on the crystallite sizes, crystal pattern, and optical property of the prepared catalysts were investigated by means of techniques such as scanning electron microscopy (SEM), X‐ray diffraction (XRD), BET surface area, and UV‐vis diffuse absorption spectroscopy. SEM observation showed that the prepared TiO 2 fibers possessed fibrous shape inherited from the cotton fiber and had a hollow structure. As confirmed by XRD and UV‐vis diffuse absorption spectroscopy examinations, Ce‐doping restrained the growth of grain size and extended the photoabsorption edge of TiO 2 hollow fiber into the visible light region. The present photocatalyst showed higher photocatalytic reactivity in photodegradation of highly concentrated methylene blue (MB) solutions than pure TiO 2 under UV and visible light, and the amount of Ce‐doped significantly affected the catalytic property. In the experiment condition, the photocatalytic activity of 0.5 mol% Ce‐doped TiO 2 fiber was optimal of all the prepared samples. In addition, the possibility of cyclic usage of the photocatalyst was also confirmed. The material was easily removed by centrifugal separation. Therefore, using the template method and by doping with cerium, TiO 2 may hopefully become a low‐energy consuming, high activity and green environmentally friendly catalytic material. 相似文献
14.
Anatase TiO 2/nanocellulose composite was prepared for the first time via a one-step method at a relatively low temperature by using cellulose nanofibers as carrier and tetrabutyl titanate as titanium precursor. The morphology, structure and element composition of the composite were characterized by SEM, EDS, TEM, XRD, XPS and UV–vis DRS. The specific surface area and thermal stability of the composite were investigated by N 2 adsorption–desorption and thermogravimetric analysis, respectively, and the band gaps of the prepared photocatalysts were calculated based on the UV–vis DRS results. In addition, the prepared composite was used for the photocatalytic degradation of methyl orange (aqueous solution, 40 mg L −1). It was found that the composite had a good morphology and anatase crystal structure, and Ti-O-C bond was formed between TiO 2 and nanocellulose. The specific surface area of composite was increased and the thermal stability was decreased compared with the cellulose nanofiber. Moreover, the degradation rate of methyl orange was achieved as 99.72% within 30 min, and no obvious activity loss was observed after five cycles. This work might give some insights into the design of efficient photocatalysts for the treatment of organic dye wastewater. 相似文献
15.
Bi-layer WO 3–TiO 2 coatings have been synthesised on stainless steel (SS) substrates by consecutive cathodic electrodeposition of WO 3 (from peroxytungstate solutions) and TiO 2 electrosynthesis (from titanium oxosulfate solutions). The resulting TiO 2–WO 3/SS photoelectrodes have been screened for their photoresponse under ultraviolet (UV) and visible (vis) light illumination by photovoltammetry in supporting electrolyte (sodium sulfate) and malachite green (a typical dye) solutions. They were also evaluated for malachite green photooxidation during constant potential bulk photoelectrolysis. It was found that both photocurrent values and dye removal rates were higher at TiO 2–WO 3/SS than at plain WO 3/SS photoelectrodes, under both UV and vis illumination (up to 85% and 67% malachite green degradation has been achieved respectively from its 10 ppm solutions after 2 h). The enhancement of the UV and, as reported here for the first time, vis photocatalytic activity of WO 3 by the inclusion of TiO 2 is interpreted by reduced electron-hole recombination rates due to electron transfer from TiO 2 to WO 3 (during UV activation) and hole transfer from WO 3 to TiO 2 (during UV and vis light activation). 相似文献
16.
Melamine was added to the precursor of TiO2, then TiO2 prepared by hydrothermal, while melamine was modified. Subsequently, a series of Z-scheme TiO2/g-C3N4 heterojunction composites were successfully synthesized by simple calcination. The morphology and structure of samples were characterized by XRD, FT-IR, UV–vis DRS, SEM, TEM, PL and BET. The photocatalytic activity of these samples has been investigated by degradation of Rhodamine B (RhB), and results indicated that photocatalytic activity of the as-prepared samples was greatly influenced by the content of titanium tetrabutoxide in precursors and the hydrothermal time. The degradation rate of TiO2/g-C3N4-1 to RhB was the best, which was 5.05-fold of pure TiO2 (19.61%) and 2.25-fold of bulk g-C3N4 (44.06%), respectively. The trapping experiment results showed that ·O2? and h+ were main active species during degradation of RhB. The photocatalytic activity of the sample did not decrease significantly after 4 cycles. The unique Z-scheme heterojunction between TiO2 and g-C3N4 improved photocatalytic activity of the samples under visible light. 相似文献
17.
The photocatalytic degradation of azo dyes with different structures (amaranth, sunset yellow and tartrazine) using TiO 2-Pt nanoparticles (TPt), TiO 2-Pt/graphene oxide (TPt-GO) and TiO 2-Pt/reduced graphene oxide (TPt-rGO) composites were investigated in the presence of UV and natural sunlight irradiation. The composites were prepared by a combined chemical-thermal method and characterized by Transmission Electron Microscopy (TEM), X-ray powder diffraction (XRD), Infrared (FTIR) and UV–Vis spectroscopy. The modification of TiO 2-Pt with graphene oxide shifted its optical absorption edge towards the visible region and increased its photocatalytic activity under UV and natural sunlight irradiation. The efficiency of catalysts on azo dyes degradation (in similar conditions) reached high values (above 99%) under sunlight conditions, proving the remarkable photocatalytic activities of obtained composites. TPt-GO nanocomposite exhibited higher photoactivity than TPt or TPt-rGO, demonstrating degradation efficiencies of 99.56% for amaranth, 99.15% for sunset yellow and 96.23% for tartrazine. The dye photodegradation process follows a pseudo-first-order kinetic with respect to the Langmuir-Hinshelwood reaction mechanism. A direct dependence between azo dyes degradation rate and chemical structure of dyes has been observed. 相似文献
18.
Photocatalytic multilayer nanocomposite films composed of anatase TiO 2 nanoparticles and lignosulfonates (LS) were fabricated on quartz slides by the layer‐by‐layer (LBL) self‐assembly technique. X‐ray photoelectron spectroscopy (XPS), UV‐vis spectroscopy and atomic force microscopy (AFM) were used to characterize the TiO 2/LS multilayer nanocomposite films. Moreover, the photocatalytic properties (decomposition of methyl orange and bacteria) of multilayer nanocomposite films were investigated. XPS results indicated that the intensities of titanium and sulfur peaks increased with the LBL deposition process. A linear increase in absorbance at 280 nm was found by UV‐Vis spectroscopy, suggesting that stepwise multilayer growth occurs on the substrate and this deposition process is highly reproducible. AFM images showed that quartz slide was completely covered by TiO 2 nanoparticles when a 10‐bilayer multilayer film was formed. The decomposition efficiency of methyl orange by TiO 2/LS multilayer films under the same UV irradiation time increased linearly with the number of TiO 2 layers, and the results of decomposition of bacteria under UV irradiation showed that TiO 2/LS multilayer nanocomposite films exhibited excellent decomposition activity of bacteria ( Escherichia coil). 相似文献
19.
Layered photocatalytic materials M 1/3TiNbO 5 (M = Fe, Ce) were prepared by ion-exchange of KTiNbO 5 with M(NO 3) 3. The parent KTiNbO 5 was synthesized with titanium (IV) isopropoxide and niobium oxalate by a novel polymerized complex (PC) method. The micro-structures and spectral response features of the as-prepared samples were characterized by powder X-ray diffraction (XRD), transmission electron microscope (TEM), laser Raman spectroscopy (LRS) and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). The results revealed that there was a significant interaction between the interlayer cation and the terminal NbO (TiO) bond in the NbO 6 (TiO 6) unit of the laminates. Photocatalytic performance was evaluated in oxidation of ethyl mercaptan under natural and UV light irradiation. It can be deduced that the photocatalytic oxidization performance can be directly affected by the characteristics of the interlayer cations. 相似文献
20.
Two different types of nitrogen-containing TiO 2 were synthesized via an acid-modified sol–gel method. Yellow-colored interstitial and white substitutional nitrogen-containing TiO 2 powders were characterized by means of X-ray diffraction, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller specific surface area and Barrett–Joyner–Halenda pore size distribution analyses, scanning electron microscopy, transmission electron microscopy and UV–vis absorption spectroscopy. The band gaps of interstitial and substitutional nitrogen-containing TiO 2 ceramics were estimated from UV–vis spectroscopy data to be 2.6 and 2.8 eV, respectively. Prepared substitutional nitrogen-containing TiO 2 featured steep light absorption edge with an approximately parallel characteristic to that in pure TiO 2. This fact is due to band-to-band visible light absorption ability of substitutional nitrogen-containing TiO 2. The photocatalytic properties of the produced nitrogen-containing TiO 2 samples were compared for the degradation of Direct Red 28 azo dye. Further studies were also devised to compare the catalytic efficiency of the nitrogen-containing TiO 2 powders with the pure TiO 2 synthesized via the similar sol–gel method. The produced nitrogen-containing TiO 2 samples revealed superior photocatalytic properties in comparison with pure TiO 2 due to their remarkable band gap narrowing, surface oxygen vacancies and much more surface defects. The results also revealed that the substitutional nitrogen-containing TiO 2 is the most effective photocatalyst under ultraviolet and visible light irradiation. 相似文献
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