共查询到20条相似文献,搜索用时 12 毫秒
1.
Veljko R. Djokić Aleksandar D. Marinković Miodrag Mitrić Petar S. Uskoković Rada D. Petrović Velimir R. Radmilović Djordje T. Janaćković 《Ceramics International》2012
A method for the preparation of efficient TiO2/multi-wall carbon nanotubes nanocomposite photocatalysts by precipitation of anatase TiO2 nanoparticles onto differently oxidized carbon nanotubes is presented. The precursor compound titanium(IV) bromide was hydrolyzed producing pure anatase phase TiO2 nanoparticles decorated on the surface of the oxidized carbon nanotubes. The oxidative treatment of the carbon nanotubes influenced the type, quantity and distribution of oxygen-containing functional groups, which had a significant influence on the electron transfer properties, i.e., the photocatalytic activity of the synthesized nanocomposites. The results of C.I. Reactive Orange 16 photodegradation in the presence of all the synthesized nanocomposites showed their better photocatalytic activity in comparison to the commercial photocatalyst Degussa P-25. 相似文献
2.
TiO2 particles supported on multi-walled carbon nanotubes (MWCNTs) were prepared using a sol–gel method to investigate their photocatalytic activity under simulated solar irradiation for the degradation of methyl orange (MO) in aqueous solution. The prepared composites were analyzed using XRD, SEM, EDS and UV–vis absorption spectroscopy. The results of this study indicated that there was little difference in the shape and structure of MWCNTs/TiO2 composite and pure TiO2 particles. The composite exhibited enhanced absorption properties in the visible light range compared to pure TiO2. The degradation of MO by MWCNTs/TiO2 composite photocatalysts was investigated under irradiation with simulated solar light. The results of this study indicated that MWCNTs played a significant role in improving photocatalytic performance. Different amounts of MWCNTs had different effects on photodegradation efficiency, and the most efficient MO photodegradation was observed for a 2% MWCNT/TiO2 mass ratio. Photocatalytic reaction kinetics were described using the Langmuir–Hinshelwood (L–H) model. The photocatalyst was reused for eight cycles, and it retained over 95.2% photocatalytic degradation efficiency. Possible decomposition mechanisms were also discussed. The results of this study indicated that photocatalytic reactions with TiO2 particles supported on MWCNTs under simulated solar light irradiation are feasible and effective for degrading organic dye pollutants. 相似文献
3.
N. Bouazza M. Ouzzine M.A. Lillo-Rdenas D. Eder A. Linares-Solano 《Applied catalysis. B, Environmental》2009,92(3-4):377-383
In this work, we investigated titanium dioxide (TiO2) nanotubes and CNT–TiO2 hybrid materials for the photocatalytic oxidation (PCO) of propene at low concentration (100 ppmv) in gaseous phase. The materials were prepared via sol–gel method using sacrificial multi-walled carbon nanotubes (CNT) as templates and subsequent heat treatments to obtain the desired crystalline phase (anatase, rutile or a mixture of both) and eventually to remove the carbon template. We also studied rutile nanotubes for the first time and demonstrate that the activity strongly depends on the crystalline composition, following rutile < anatase < anatase/rutile mixture. The enhanced activity of the anatase–rutile mixture is attributed to the decrease in the electron–hole pair recombination due to the multiphasic nature of the particles. The key result of this work is the exceptional performance of the CNT–TiO2 hybrid, which yielded the highest observed photocatalytic activity. The improved performance is attributed to synergistic effects due to the hybrid nature of the material, resulting in small anatase crystalline sizes (CNT act as heat sinks) and a reduced electron–hole pair recombination rate (CNTs act as electron traps). These results demonstrate the great potential of hybrid materials and stimulate further research on CNT-inorganic hybrid materials in photocatalysis and related areas. 相似文献
4.
Hyun-Jin HongSwapan Kumar Sarkar Byong-Taek Lee 《Journal of the European Ceramic Society》2012,32(3):657-663
In this study, needle-shape TiO2 fibers were successfully fabricated inside a micro-channeled Al2O3-ZrO2 composite porous membrane system using sol-gel method. The micro-channeled Al2O3-ZrO2 composite was fabricated using the fibrous monolithic (FM) process. Pure anatase phase TiO2 was crystallized from the as-coated amorphous phase during calcination at 510 °C. The TiO2 fibers grew on the surface frame of the micro-channeled Al2O3-ZrO2 composite membrane and fully covered the inside of the micro-channeled pores. The specific surface area of the TiO2 coated membrane system was dramatically increased by over 100 fold compared to that of the non-coated system. The photocatalytic activity of the membrane was also assessed and was shown to very effectively convert organic materials. Thus, this novel membrane holds promise for use as an advanced filtration system. 相似文献
5.
A porous glass tube with a composition of 96SiO2·4B2O3 (wt%) supported TiO2 shows high photooxidation activity due to its transparency and large surface area. The surface area of the porous glass tube supported TiO2 is 10,000 times larger than that of conventional materials. TiO2 crystals supported are anatase type. Transparency of the porous glass tube is very important. Herein, sol–gel and chemical vapor deposition (CVD) processes were employed as TiO2 supporting processes. CVD process is more effective. For instance, an aqueous methylene blue solution with 1 ppm concentration almost thoroughly decomposes at a contact time of 300 s using porous glass tube supported TiO2 prepared by CVD process under irradiating with 10 W low-pressure mercury lamp, on the other hand, opaque porous alumina tube supported TiO2 was only 25%. The smaller the pore size of the porous glass tube, the larger the transparency and the permeation resistance through porous glass tube. Hence, porous glass tube with ca. 40 nm pore diameter is suitable from the standpoint of a practical use. 相似文献
6.
Akbar Eshaghi Reza MozaffariniaMahmoud Pakshir Ameneh Eshaghi 《Ceramics International》2011,37(1):327-331
TiO2 nanocomposite films with different concentrations of TiO2 MT-150A nanoparticles were immobilized on glass substrates using a dip coating process. The crystalline structure and surface chemical state of nanocomposite film properties were examined by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. The specific surface area and morphology of TiO2 MT-150A nanoparticles were evaluated by the BET method and Field Emission Scanning Electron Microscopy (FE-SEM). The photocatalytic activities of films were evaluated by the methyl orange decoloring rate. XPS measurements showed that the oxygen amount (%) was related to the film composition. The composite film with 10 g/L MT-150A loading yielded the highest amount of surface oxygen (26.82%) and TiO2 rutile showed the lowest amount of surface oxygen (13.67%) in the form of surface hydroxyl groups. The remaining oxygen was identified as lattice oxygen. In addition, the nanocomposite film with 10 g/L MT-150A loading yielded the highest photocatalytic activity. 相似文献
7.
Rod-like N-doped TiO2/Ag composites were successfully synthesized by a modified sol–gel method, without adding any surfactants. The entire preparation differs from the traditional sol–gel synthesis of TiO2 that the reaction can get controlled by adjusting the flow speed of water vapor and NH3. Characterization results show that as-prepared samples were uniform nanorods with an average length of ca. 3 µm and a cross section diameter of ca. 150 nm. The rod-like structure was formed during the annealing process. A possible mechanism was proposed to illustrate the formation of rod-like Ag–N–TiO2. The degradation of methylene blue performed under visible light with the prepared nanorods as the photocatalyst demonstrated the photocatalytic activities of TiO2 can be improved by the synergistic effect of N doping and Ag modification. In addition, as-prepared TiO2-based photocatalyst exhibits a significantly enhanced photo-chemical stability after 5 catalytic cycles mainly due to the rod-like morphology. This indicated that they have some potential value in practical application. 相似文献
8.
Dye-sensitized solar cells (DSCCs) in the form of mixed nanostructures containing TiO2 nanoparticles and nanowires with different weight ratios and phase compositions are reported. X-ray diffraction and field emission scanning electron microscopy analyses revealed that the synthesized TiO2 nanoparticles had average crystallite size in the range 21–39 nm, whereas TiO2 nanowires showed diameter in the range 20–50 nm. The indirect optical band gap energy of TiO2 nanowires, anatase- and rutile-TiO2 nanoparticles was calculated to be 3.35, 3.28 and 3.17 eV, respectively. The power conversion efficiency of the solar cells changed with nanowire to nanoparticle weight ratio, reaching a maximum at a specific value. An increase of 4.3% in cell efficiency was achieved by introducing 10 wt% nanowire into the as-synthesized TiO2 nanoparticles (WP1 cell). Furthermore, an increase of 27.6% in cell efficiency was achieved by using crystalline anatase-TiO2 nanoparticles rather than as-synthesized TiO2 nanoparticles in WP1 solar cell. It was found that the power conversion efficiency and short circuit current of WP1 cell were decreased down to around 30.8% and 39.1%, respectively using rutile nanoparticles rather than anatase nanoparticles. The improvement of cell efficiency was related to rapid electron transport and less recombination of photogenerated electrons, as confirmed by electrochemical impedance spectroscopy. 相似文献
9.
10.
Astri Bjørnetun Haugen Izumi KumakiriChristian Simon Mari-Ann Einarsrud 《Journal of the European Ceramic Society》2011,31(3):291-298
TiO2, TiO2/Ag and TiO2/Au photocatalysts exhibiting a hollow spherical morphology were prepared by spray pyrolysis of aqueous solutions of titanium citrate complex and titanium oxalate precursors in one-step. Effects of precursor concentration and spray pyrolysis temperature were investigated. By subsequent heat treatment, photocatalysts with phase compositions from 10 to 100% rutile and crystallite sizes from 12 to 120 nm were obtained. A correlation between precursor concentration and size of the hollow spherical agglomerates obtained during spray pyrolysis was established. The anatase to rutile transformation was enhanced with metal incorporations and increased precursor concentration. The photocatalytic activity was evaluated by oxidation of methylene blue under UV-irradiation. As-prepared TiO2 particles with large amounts of amorphous phase and organic residuals showed similar photocatalytic activity as the commercial Degussa P25. The metal incorporated samples showed comparable photocatalytic activity to the pure TiO2 photocatalysts. 相似文献
11.
K. Ko
í L. Obalov L. Matjov D. Plach Z. Lacný J. Jirkovský O. olcov 《Applied catalysis. B, Environmental》2009,89(3-4):494-502
Pure TiO2 anatase particles with a crystallite diameters ranging from 4.5 to 29 nm were prepared by precipitation and sol–gel method, characterized by X-ray diffraction (XRD), BET surface area measurement, UV–vis and scanning electron microscopy (SEM) and tested in CO2 photocatalytic reduction. Methane and methanol were the main reduction products. The optimum particle size corresponding to the highest yields of both products was 14 nm. The observed optimum particle size is a result of competing effects of specific surface area, charge–carrier dynamics and light absorption efficiency. 相似文献
12.
TiO2 nanoparticles modified with 5-(p-hydroxylphenyl)-10,15,20-triphenylporphyrin (HTPP), 5-(p-hydroxylphenyl)-10,15,20-triphenylporphyrin zinc (ZnHTPP) and trans-dichloro-5-(p-hydroxylphenyl)-10,15,20-triphenylporphyrin tin (SnHTPP) were prepared in order to improve the visible photocatalytic activity of TiO2 nanoparticles. The photocatalytic activity of the modified TiO2 nanoparticles was investigated by carrying out the photodegradation of methyl orange in aqueous solution under visible light irradiation. The TiO2 nanoparticles modified with SnHTPP show the highest visible photocatalytic activity with a degradation ratio of 86% of methyl orange after 180 min irradiation among three catalysts. This result indicates that the central metal ions in porphyrins can significantly influence the sensitization efficiency of porphyrins. In addition, the photoelectrochemical behavior of the modified TiO2 nanoparticles was examined and related to their photocatalytic activity. Finally, the photocatalytic mechanism was discussed preliminarily. 相似文献
13.
The process of removal of two azo dyes (Reactive Red 198 and Direct Green 99) from water was investigated. The adsorption of azo dyes onto surfaces of pristine TiO2, P25 and carbon-modified TiO2 (at 120 °C for 24 h) was presented. The Freundlich model of adsorption isotherm was found for pristine TiO2 and TiO2-P25. Modification of TiO2 by carbon lead to the change from the Freundlich model to the Langmuir model of adsorption isotherm. For the TiO2-C photocatalyst the adsorption capacity was determined, which was almost two times higher for Direct Green 99 than Reactive Red 198 dyes. As a result we observed the increase of photocatalytic activity of carbon-modified TiO2 photocatalyst. 相似文献
14.
Isabel Santacruz Aurelio CabezaPaul Ibeh Enrique R. LosillaÁngeles G. De la Torre Miguel A.G. Aranda 《Ceramics International》2012
Commercial tiles are being produced in vast quantities. The main properties of tiles are well established but there is an increasing interest in producing ceramics with tailored-properties and advanced functionalities. One way of adding value to commercial tiles is to deposit a photocatalytic coating to obtain ‘smart’ tiles for environmental reasons, e.g. for the (photo) degradation of organic pollutants in air or in a liquid. Here, we show the manufacture of ‘smart’ tiles by formation of TiO2 coatings onto commercial tiles by a colloidal processing route based on the immersion of the substrate into a homogeneous aqueous ceramic suspension and its consolidation by agar thermogelation. The effect of the processing parameters (withdrawal rate, solid loading and gelling agent content) and the grain size on the photocatalytic activity of the final coated tiles is reported and discussed. Final coatings properties depend on the viscosity of the suspension, particle size, withdrawal rate, solid loading and gelling agent content, and hence, this dependence affects the photocatalytic activity of the coatings. 相似文献
15.
Lijuan Chen Jintao Tian Huang Qiu Yansheng Yin Xin Wang Jinhui Dai Pingwei Wu Aiping Wang Lei Chu 《Ceramics International》2009,35(8):3275-3280
The preparation of TiO2 nanofilm was conducted on common glass via the sol–gel process. Glacial acetic acid and diethanolamine were used as inhibitors to prepare acidic and alkaline TiO2 sol, respectively. XRD, SEM, and EDS characterization showed that the film prepared from acidic TiO2 sol had a narrow particle size distribution of 15–30 nm and relatively poor particle crystallization while in the case of the film from alkaline TiO2 sol the nanoparticles were in a wide range of 10–80 nm and well crystallized. The photolysis evaluation through MO degradation revealed that the film from acidic sol possessed apparently better photocatalytic activity than that from alkaline sol. Heat treatment with longer time led to a 50% increase of the photocatalytic activity for the film. 相似文献
16.
Pure anatase TiO2 photocatalyst with different Ag contents was prepared via a controlled and energy efficient microwave assisted method. The prepared material was further characterized by several analytical techniques like X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), surface area measurement (BET), Fourier transform-infrared spectroscopy (FT-IR), diffused reflectance spectroscopy (DRS), and thermogravimetric–differential thermal analysis (TGA–DTA). A 10 nm average crystallite size with nano-crystals of pseudo-cube like morphology was obtained for optimal (0.25 mol%) Ag doped TiO2. The present research work is mainly focused on the enhancement of degradation efficiency of methyl orange (MO) by doping of Ag in TiO2 matrix using UV light (365 nm). A 99.5% photodegradation efficiency of methyl orange was achieved by utilizing 0.25 mol% Ag doped TiO2 (1 g/dm3) at pH=3 within 70 min. Recyclability of photocatalyst was also studied, with the material being found to be stable up to five runs. 相似文献
17.
In this study, we report the effect of annealing (250–700 oC) on the phase transition and morphology of silver (Ag) nanoparticles (NPs) on/in titanium dioxide (TiO2) rods prepared using a polyol method. The annealed samples showed not only morphological change, i.e., a solid-to-liquid (melting) transition of Ag NPs due to its partial dissolution into the TiO2 rods, but also early stage anatase crystallization and anatase–rutile transformation of TiO2 rods under low annealing temperatures. Such findings, together with XRD and FE-SEM analyses, confirm that, upon higher annealing treatment, diffusion and coalescence leads to changes in the size and shape of the metal particles not only in the outermost regions, but also a random distribution and progressive growth of Ag clusters in the inner interface region. Here, it was shown that annealing can induce changes in morphology, as well as the chemical state and structure of Ag–TiO2. The present polyol-synthesized Ag–TiO2 composite also showed improved thermal stability. 相似文献
18.
Kwang-Dae Kim Hyun Ook Seo Chae Won Sim Myung-Geun Jeong Young Dok Kim Dong Chan Lim 《Progress in Organic Coatings》2013
TiO2 nanoparticles with a mean size of 20–30 nm were covered by ultrathin polydimethylsiloxane (PDMS) film, which shows hydrophobic properties. Surfaces consisting of the PDMS-coated TiO2 particles showed water contact angles close to 170°. In contrast to the hydrophobic films consisting of organic molecules, which can be photocatalytically decomposed on TiO2 in the presence of UV light, PDMS-coating on TiO2 was highly stable. The PDMS-coating completely suppressed the photocatalytic activity of TiO2. The unique properties of PDMS-coating can be exploited for UV protection layer and self-cleaning surfaces. 相似文献
19.
Silver nanoparticles (Ag NPs) with diameter of approximately 10 nm were prepared by the reduction of silver nitrate using green synthesis, an eco-friendly approach. The synthesized Ag NPs were homogeneously deposited on silicon dioxide (SiO2) particles modified with dopamine, leading to the formation of SiO2/polydopamine (PD)/Ag nanocomposites (NCs) with a core–shell–satellite structure investigated by transmission electron microscopy. The Ag content of SiO2/PD/Ag NCs determined by inductively coupled plasma optical emission spectrometry was approximately 5.92 wt%. The antibacterial properties of both Ag NPs and SiO2/PD/Ag NCs against Vibrio natriegens (V. natriegens) and Erythrobacter pelagi sp. nov. (E. pelagi) were investigated by bacterial growth curves and inhibition zone. Compared to Ag NPs, the SiO2/PD/Ag NCs exhibited superior long-term antibacterial activity, attributed to its controlled release of Ag+ ions. 相似文献
20.
Suzana ŠegotaLidija ?urkovi? Davor LjubasVesna Svetli?i? Ivona Fiamengo HouraNenad Tomaši? 《Ceramics International》2011,37(4):1153-1160
The application of heterogeneous photocatalysis is described as an advanced oxidation process (AOP) for the degradation of the diazo reactive dye using immobilized TiO2 as a photocatalyst. Starting TiO2 solutions were prepared with and without the addition of polyethylene glycol (PEG) and TiO2 films were directly deposited on a borosilicate glass substrate using the sol-gel dip-coating method. The surface morphology and the nanoscale roughness of TiO2 films were studied by means of atomic force microscopy (AFM). Structural properties of TiO2 were identified by X-ray diffraction (XRD). The decomposition behaviour of organic compounds from the gels was investigated using thermal gravimetry (TG) and differential scanning calorimetry (DSC). Photocatalytic activities of TiO2 films in the process of degradation of the commercial diazo textile dye Congo red (CR), used as a model pollutant, were monitored by means of UV/vis spectrophotometry. The kinetics of the degradation of the CR dye was described with the Langmuir-Hinshelwood (L-H) kinetic model.The addition of PEG to the TiO2 solution resulted in the changes in the film surface morphology, and affected the ratio of anatase-rutile crystal phases and the photocatalytic activity of TiO2. The TiO2 film prepared with PEG is characterized by higher roughness parameters (Ra, Rmax, Rq, Rz and Zmax), a lower amount of the rutile phase of TiO2, a higher amount of the anatase phase of TiO2 and a better photocatalytic activity compared to the TiO2 film without the addition of PEG. 相似文献