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1.
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
2.
E. Pavitra G. Seeta Rama Raju Seyed Majid Ghoreishian Cheol Hwan Kwak Jin Young Park Young-Kyu Han Yun Suk Huh 《Ceramics International》2019,45(4):4781-4789
Energy conservation and environmental safety are the key requirements in the modern world. We report novel orange-emitting double perovskite Ba2LaNbO6:Eu3+ (BLN:Eu3+) nanophosphor fabricated using a citrate sol-gel method for use in general illumination and photocatalysis. After annealing at 800?℃, the particles exhibited a nanorod-like morphology with monoclinic structure. The photoluminescence emission spectra exhibited an intense 5D0→7F1 transition at 594?nm and a moderate 5D0→7F2 transition at 615?nm, demonstrating that the Eu3+ ions occupied the La3+ sites with inversion symmetry. The optimal concentration of Eu3+ ions was found to be about 5?mol% for the BLN host lattice. Energy transfer from the NbO67- octahedrons to the Eu3+ ions was clearly witnessed when the BLN:Eu3+ nanophosphors were excited with both the characteristic excitation bands of Eu3+ (7F0→5L6) and NbO67- octahedrons at 392 and 380?nm, respectively. The thermal quenching temperature of 5?mol% Eu3+ ions doped BLN nanophosphors was found to be 183?℃, indicating that these nanophosphors are very stable at high temperatures. In addition, the dye removal efficiency of the proposed BLN nanophosphors was verified using Rhodamine B (RhB) dye as a model pollutant under UV irradiation. Compared to a commercial nano-ZnO catalyst, our synthesized BLN nanophosphors showed superior RhB de-colorization efficiency. Therefore, the proposed BLN:Eu3+ nanophosphors are promising multifunctional materials for photocatalysis and general lighting applications. 相似文献
3.
4.
Roberto Scotti Massimiliano DArienzo Franca Morazzoni Ignazio Renato Bellobono 《Applied catalysis. B, Environmental》2009,88(3-4):323-330
Hydrothermally produced TiO2 powders with different phase composition (anatase, rutile and mixed phase) were immobilized on glass fibers and tested in the phenol mineralization process. Both H2O2 and O2 were used as oxygen donors, and their performances were compared with those of the same TiO2 samples as slurries.The catalytic properties of the immobilized different crystalline phases, rutile and anatase, show the same trend as the slurry samples: pure rutile displays the highest catalytic efficiency in the presence of H2O2, while samples containing anatase improve the photodegradation efficacy with O2. It was suggested that the stability of the photogenerated electron–hole couple allows high activity of rutile in the presence of H2O2, while the relevant oxygen chemisorption on anatase causes high catalytic activity in the presence of O2. A four parameters kinetics model shows that both reaction steps, the phenol degradation and the mineralization of the intermediates, are photoactivated by TiO2.Photoactivity of the coated glass fibers is generally lower than that of slurries, even if their efficiencies are almost comparable when the oxidation is performed by H2O2, while much lower when the oxygen donor is O2. As a matter of fact, the morphology of immobilized catalysts shows the presence of chestnut burr aggregates of large rutile crystalline rods on the glass fiber, which are much less compact than the aggregates of small anatase particles. This preserves rutile surface area from the coarsening effects; thus, when rutile is the more active species, as in the presence of H2O2, the photocatalytic activity is less affected by immobilization. 相似文献
5.
Galina N. Kryukova Galina A. Zenkovets Alexei A. Shutilov Michael Wilde Kerstin Günther Dieter Fassler Klaus Richter 《Applied catalysis. B, Environmental》2007,71(3-4):169-176
TiO2 (anatase) with different microstructure was synthesized by thermal hydrolysis of the titanyl sulfate and studied by X-ray powder diffraction, high resolution transmission electron microscopy and UV–vis diffuse reflectance spectroscopy. The effect of titanium dioxide structure, regular or distorted, on the photocatalytic degradation of Acid Orange 7 Dye (AO7) in water upon ultraviolet light was studied. It was found that synthesized TiO2 possesses a relatively high reactivity when illuminated but also show different adsorption in the dark. The relationship between these behaviors depends on the real structure of the catalysts. Catalysts with a perfect structural ordering formed after heating at temperature higher than 500 °C show better photocatalytic performance. Small amount of Pt added into the TiO2 structure was found to improve further the catalyst reactivity. Pt-modified titania catalysts oxidize AO7 more efficiently than P-25 Degussa TiO2. Doping effect of Pt on the structural and photocatalytic properties of the samples is discussed. 相似文献
6.
F.C. Correia M. Calheiros J. Marques J.M. Ribeiro C.J. Tavares 《Ceramics International》2018,44(18):22638-22644
Dendritic growth of bismuth oxide nanostructured films was accomplished by reactive magnetron sputtering. The deposition of the Bi2O3 template layers was adapted to abide a vapour-liquid-solid mechanism in order to develop a 3D growth morphology with high surface area templates for photocatalytic applications. TiO2 photocatalytic thin films were deposited at a later stage onto Bi2O3 layers. The obtained heterostructured films were characterized by scanning electron microscopy, X-ray diffraction and atomic force microscopy. Additionally, the photocatalytic efficiency was assessed by conducting an assay using methylene blue dye as testing pollutant under a UV-A illumination. The photocatalytic tests revealed that the Bi2O3 layers functionalized with TiO2 thin films are more efficient at degrading the pollutant, by a factor of 6, when compared with the individual layered films. 相似文献
7.
We report Eu3+ doped transparent glass-ceramics (GCs) containing bismuth layer-structured ferroelectric (BLSF) CaBi2Ta2O9 (CBT) as the major crystal phase. The CBT crystal phase was generated in a silica rich glass matrix of SiO2-K2O-CaO-Bi2O3-Ta2O5 glass system synthesized by melt quenching technique followed by controlled crystallization through ceramming heat-treatment. Non-isothermal DSC study was conducted to analyze crystallization kinetics of the glass in order to understand the crystallization mechanism. The optimum heat-treatment protocol for ceramization of precursor glass that has been determined through crystallization kinetics analysis was employed to fabricate transparent GCs containing CBT nanocrystals, which was otherwise difficult. Structural analysis of the GCs was carried out using XRD, TEM, FESEM and Raman spectroscopy and results confirmed the existence of CBT nanocrystals. The transmittance and optical band gap energies of the GCs were found to be less when compared to the precursor glass. The refractive indices of the GCs were increased monotonically with increase in heat-treatment time, signaling densification of samples upon heat-treatment. The dielectric constants (εr) of the GCs were progressively increased with increase in heat-treatment duration indicating evolution of ferroelectric CBT crystals phase upon heat-treatment. 相似文献
8.
Zoltn Ambrus Nndor Balzs Tünde Alapi Gyula Wittmann Pl Sipos Andrs Dombi Kroly Mogyorsi 《Applied catalysis. B, Environmental》2008,81(1-2):27-37
Iron(III)-doped titanium dioxide photocatalysts were prepared from aqueous titanium(III) chloride solution in the presence of dissolved FeCl3 (0–10.0 at.% relative to TiCl3) by co-precipitation method. The precipitate was completely oxidized in the aerated suspension, hydrothermally treated, washed and calcinated. The structure of the powders was characterized by thermoanalysis (TG-DTA), diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), nitrogen adsorption and transmission electron microscopy (TEM). The light absorption of the iron-containing powders is red shifted relative to the bare sample. The particle size and anatase content were found to significantly decrease at iron contents ≥6.0 at.% which is accompanied with the increase of their specific surface area. XANES measurements showed that the local structure of iron systematically changes with the variation of the dopant concentrations: at higher Fe-contents, hematite- or goethite-like environments were observed, consistent with the formation of separate X-ray amorphous Fe(III)-containing phases. The local structure of iron gradually transformed with decreasing dopant concentrations, possibly due to substitution of Fe(III) in the titania (TiO2) crystal lattice. Energy dispersive X-ray analysis (EDX) and chemical analysis was used to characterize the iron content of the samples in the bulk and X-ray photoelectron spectroscopy (XPS) in the surface layer of the particles. The photocatalytic performance of the prepared photocatalysts was compared with the activity of Aldrich anatase under UV–vis and VIS irradiation in two different photoreactors. Maximum photocatalytic performance was found at 3.0 at.% iron concentration for UV–vis and at 1.2 at.% for VIS irradiation. Doping with iron(III) ions increased the photodegradation rate of phenol by a factor of three for UV–vis irradiation and by a factor of two for VIS irradiation, relative to the bare photocatalyst. 相似文献
9.
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
10.
Francielly Roussenq Cesconeto Mario Borlaf Maria Isabel Nieto Antonio Pedro Novaes de Oliveira Rodrigo Moreno 《Ceramics International》2018,44(1):301-309
CaTiO3 and CaTiO3/TiO2 nanocompounds have been synthesized through a colloidal sol-gel route using Ca2+/TiO2 nanoparticulate sols. The peptization time was determined so that as higher is the Ca2+ concentration, shorter is the peptization time. The obtained cryogels from the respective sols were calcined at different temperatures (300–900 °C) and the structural and morphological changes were characterized mainly by X-ray diffraction and transmission electron microscopy. In all cases, the formation of the CaTiO3 phase was observed after calcination at temperatures as low as 500 °C. Mesoporous cryogels with nanoparticles with sizes below 50 nm were obtained and their photocatalytic activity changes as a function of the calcination temperature and the applied wavelength were determined. Quantum yield values revealed that either CaTiO3 or the CaTiO3/TiO2 (0.4 M ratio) compound can be chosen as the most efficient photocatalyst at higher calcination temperatures and longer wavelengths, while TiO2 is more effective at low calcination temperatures and shorter wavelengths. 相似文献
11.
The deactivation of TiO2 Degussa P25 during the gas-phase photocatalytic oxidation of ethanol has been studied. Water vapor plays a clear competitive role for surface sites adsorption, thus hampering the ethanol photo-oxidation. Dark adsorption of ethanol on a fresh catalyst shows a Langmuirian behavior with the formation of a monolayer of adsorbate. Dark adsorption in a TiO2 surface that has been used in consecutive photocatalytic experiments of ethanol degradation gives non-Langmuirian isotherms, indicating the existence of noticeable changes of the catalyst surface structure. After several irradiations the catalyst activity decreases. Such deactivation has been investigated, observing that the rate constant of ethanol and acetaldehyde (its main degradation product) oxidation decreases with irradiation time. Several surface treatments have been studied in order to find suitable procedures for catalytic activity recovery, but regular decay of activity is always observed after every treatment. 相似文献
12.
Haizhen Lai Junfei Zhang Dejian Hou Hequn Guan Xinyu Ye 《Ceramics International》2018,44(13):15072-15078
The investigation on single phase multi-color phosphors is highly meaningful for near-ultraviolet chip based white light emitting diodes. In this work, a series of Eu2+ and Tb3+ singly doped and Eu2+/Tb3+ codoped Sr5(PO4)3Cl phosphors were synthesized via a high-temperature solid state reaction method. The luminescence spectra and decay curves of Eu2+ and Tb3+ singly doped samples were discussed, the optimal doping concentrations were determined. Thanks to the spectra overlap between Eu2+ and Tb3+, nonradiative energy transfer from Eu2+ to Tb3+ was investigated. It is found electric dipole-dipole interaction played the main role for the energy transfer in codoped samples, the highest energy transfer efficiency was calculated to be 60.98%. Tunable emissions are observed for codoped samples by adjusting doping concentration. The thermal quenching properties were discussed and the activation energy (ΔE) was estimated in the present work. 相似文献
13.
Ping Chen Yiwei Mao Shaodong Hou Yang Chen Xiaofen Liu Yang Lou Aichen Chen Luyun Yang Jinyan Li Nengli Dai 《Ceramics International》2019,45(1):233-238
Eu2+/Eu3+ ions doped silica glasses contained In2O3 nanoparticles (NPs) have been fabricated by using nanoporous silica glasses. Interestingly, efficient energy transfer from In2O3 NPs to Eu2+/Eu3+ ions enhanced the photoluminescence (PL) emission of Eu2+/Eu3+ ions, which derives from lattice defects in In2O3 NPs. Our work has not only demonstrated a facile way to fabricate NPs and rare earth ions co-doped silica glasses, but also extended the applications of semiconductor oxide NPs such as In2O3 NPs. 相似文献
14.
Vclav tengl Snejana Bakardjieva Nataliya Murafa Vendula Houkov Kamil Lang 《Microporous and mesoporous materials》2008,110(2-3):370-378
Photocatalytic active TiO2/ZnS composites were prepared by homogeneous hydrolysis of mixture of titanium oxo-sulphate and zinc sulphate in aqueous solutions with thioacetamide. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission microscopy (HRTEM) and electron diffraction (ED). The nitrogen adsorption–desorption was used for surface area (BET) and porosity determination. Diffuse reflectance UV/VIS spectra for evaluation of photophysical properties were recorded in the diffuse reflectance mode (R100) and transformed to an absorption spectra through the Kubelka–Munk function. The method of UV/VIS diffuse reflectance spectroscopy was employed to estimate band-gap energies of the prepared TiO2/ZnS nanocomposites. The photoactivity of the prepared TiO2/ZnS nanocomposites was assessed by the photocatalytic decomposition of Orange II dye in an aqueous slurry under irradiation of 255 nm, 365 nm and 400 nm wavelength. Under the same conditions, the photocatalytic activity of the commercially available photocatalyst (Degussa P25), the pure anatase TiO2 and sphalerite ZnS were also examined. The composite sample having the highest catalytic activity was obtained by hydrolysis of mixture solutions 0.63 M TiOSO4 and 0.08 M ZnSO4 · 7H2O. 相似文献
15.
锌掺杂多孔SiO2/TiO2(多孔Zn-SiO2/TiO2)复合薄膜自清洁玻璃以含聚乙二醇的钛醇盐和硅醇盐的复合溶胶前驱体通过浸渍提拉法制备。结果表明,在TiO2薄膜中添加SiO2可抑制TiO2晶粒长大,并提高TiO2薄膜的亲水性;随着聚乙二醇添加量的增加,锌掺杂多孔SiO2/TiO2薄膜的孔隙增多,表面积增大;经500℃煅烧的多孔Zn-SiO2/TiO2复合薄膜中,TiO2主要为催化效率高的锐钛矿相;多孔Zn-SiO2/TiO2复合薄膜表观光催化降解速率明显高于未掺锌多孔SiO2/TiO2薄膜。 相似文献
16.
Wen-Cheng TzouChien-Chen Diao Cheng-Fu Yang Chin-Guo KuoChien-Jung Huang 《Ceramics International》2011,37(4):1341-1344
2ZnO + SiO2 + X mol% TiO2 (Zn2SiO4-X-TiO2, 1 ≤ X ≤ 3) and 2ZnO + SiO2 + 3 mol% MnO2 (Zn2SiO4-3-TiO2) compositions were prepared using nanoscale ZnO, SiO2, TiO2, and MnO2 particles. The mixing powders were calcined between 1000 °C and 1300 °C in a N2 atmosphere. Zn2SiO4 was the only phase in the calcined Zn2SiO4-X-TiO2 phosphors. We found that the photoluminescence (PL) properties of synthesized Zn2SiO4-X-TiO2 phosphors revealed these to be blue rather than green. The effects of TiO2 content and calcining temperature on the PL properties of Zn2SiO4-X-TiO2 phosphors were rigorously investigated. 相似文献
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18.
Iain Liu Linda A. Lawton Detlef. W. Bahnemann Peter K.J. Robertson 《Applied catalysis. B, Environmental》2005,60(3-4):245-252
Titanium dioxide (TiO2) photocatalysis has been used to initiate the destruction of nodularin, a natural hepatotoxin produced by cyanobacteria. The destruction process was monitored using liquid chromatography–mass spectrometry analysis which has also enabled the identification of a number of the photocatalytic decomposition products. The reduction in toxicity following photocatalytic treatment was evaluated using protein phosphatase inhibition assay, which demonstrated that the destruction of nodularin was paralleled by an elimination of toxicity. 相似文献
19.
Orawan Wiranwetchayan Surin Promnopas Surachet Phadungdhitidhada Anukorn Phuruangrat Titipun Thongtem Pisith Singjai Somchai Thongtem 《Ceramics International》2019,45(4):4802-4809
Perovskite LaFeO3 nanoparticles were successfully synthesized by microwave plasma method combined with high temperature calcination at 700–1000?°C. The influences of calcination temperature on morphology, crystalline structure, purity and the atomic compositions of samples were studied. The photocatalytic performance of LaFeO3 was evaluated though the photodegradation of Rhodamine B (RhB) under visible light. In this research, the orthorhombic LaFeO3 nanoparticles showed band gaps in the range of 2.15–2.30?eV. The particle size increased with increasing in the calcination temperature, leading to the decreasing in the surface area. The LaFeO3 sample calcined at 900?°C showed the highest photodegradation of 77.8% and the apparent rate constant of 0.0077?min?1 within 180?min because of the narrower of band gap and the higher crystalline degree and oxygen adsorption. 相似文献
20.
Cu2O/TiO2, Bi2O3/TiO2 and ZnMn2O4/TiO2 heterojunctions were studied for potential applications in water decontamination technology and their capacity to induce an oxidation process under VIS light. UV–vis spectroscopy analysis showed that the junctions-based Cu2O, Bi2O3 and ZnMn2O4 are able to absorb a large part of visible light (respectively, up to 650, 460 and 1000 nm). This fact was confirmed in the case of Cu2O/TiO2 and Bi2O3/TiO2 by photocatalytic experiments performed under visible light. A part of the charge recombination that can take place when both semiconductors are excited was observed when a photocatalytic experiment was performed under UV–vis illumination. Orange II, 4-hydroxybenzoic and benzamide were used as pollutants in the experiment. Photoactivity of the junctions was found to be strongly dependent on the substrate. The different phenomena that were observed in each case are discussed. 相似文献