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  1. 9 Polish Journal of Chemical Technology

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  1. 7 Kaczmarek D.

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1
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Effect of dopant concentration on photocatalytic activity of TiO2 film doped by Mn non-uniformly

100%
Zhang K., Xu W., Li X., Zheng S., Xu G.
Open Chemistry
|
2006
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vol. 4
|
issue 2
234-245
EN
The thin films of TiO2 doped by Mn non-uniformly were prepared by sol-gel method under process control. In our preceding study, we investigated in detail, the effect of doping mode on the photocatalytic activity of TiO2 films showing that Mn non-uniform doping can greatly enhance the activity. In this study we looked at the effect of doping concentration on the photocatalytic activity of the TiO2 films. In this paper, the thin films were characterized by UV-vis spectrophotometer and electrochemical workstation. The activity of the photocatalyst was also evaluated by photocatalytic degradation rate of aqueous methyl orange under UV radiation. The results illustrate that the TiO2 thin film doped by Mn non-uniformly at the optimal dopant concentration (0.7 at %) is of the highest activity, and on the contrary, the activity of those doped uniformly is decreased. As a comparison, in 80 min, the degradation rate of methyl orange is 62 %, 12 % and 34 % for Mn non-uniform doping film (0.7 at %), the uniform doping film (0.7 at %) and pure titanium dioxide film, respectively. We have seen that, for the doping and the pure TiO2 films, the stronger signals of open circuit potential and transient photocurrent, the better photocatalytic activity. We also discusse the effect of dopant concentration on the photocatalytic activity of the TiO2 films in terms of effective separation of the photon-generated carriers in the semiconductor.
2
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A review on the synthesis of TiO2 nanoparticles by solution route

100%
Gupta S., Tripathi M.
Open Chemistry
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2012
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vol. 10
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issue 2
279-294
EN
TiO2 can be prepared in the form of powder, crystals, or thin films. Liquid-phase processing is one of the most convenient and utilized methods of synthesis. It has the advantage of allowing control over the stoichiometry, production of homogeneous materials, formation of complex shapes, and preparation of composite materials. However, there may be some disadvantages such as expensive precursors, long processing times, and the presence of carbon as an impurity. In comparison, the physical production techniques, although environment friendly, are limited by the size of the produced samples which is not sufficient for a large-scale production. The most commonly used solution routes in the synthesis of TiO2 are reviewed.
3
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Optical and electrical properties of nanocrystalline TiO2:Pd semiconducting oxides

100%
Sieradzka K., Kaczmarek D., Domaradzki J., Prociów E., Mazur M., Górnicka B.
Open Physics
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2011
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vol. 9
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issue 2
313-318
EN
Electrical and optical properties of TiO2:Pd thin films deposited from Ti-Pd mosaic targets sputtered in reactive oxygen plasma have been studied. The properties were investigated for thin films with the Pd amount of 5.5 at. %, 8.4 at. % and 23 at. %. Based on resistivity measurements a drop from 103 down to almost 10−3Ωcm has been recorded when the Pd amount was varied from 5.5 at. % to 23 at. %, respectively. Moreover, it was shown that doping with different amounts of Pd results in the possibility of obtaining both types of electrical conduction: n-type for the TiO2 with 5.5 at. % and 8.4 at. % of Pd and p-type for the TiO2 with 23 at. % of Pd thin films. From optical measurements it has been found that as the Pd amount was increased the transmission through the thin films was reduced and position of the fundamental absorption edge was shifted toward a longer wavelength range of up to 600 nm. The optical band gap was calculated for direct and indirect transitions from optical absorption spectra. Structural properties were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). The XRD patterns displayed occurrence of the crystalline, TiO2-rutile for lower Pd amounts (5.5 at. %, 8.4 at. %), while the TiO2:Pd (23 at. %) thin films displayed XRD-amorphous behaviour. Images obtained from AFM displayed dense, nanocrystalline structure with homogenous distribution of crystallites. Additionally performed secondary ion mass spectroscopy investigation confirmed homogenous distribution of Pd in the whole thickness of the prepared thin films.
4
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Photocatalytic properties of Ru-doped titania prepared by homogeneous hydrolysis

100%
Houšková V., Štengl V., Bakardjieva S., Murafa N., Tyrpekl V.
Open Chemistry
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2009
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vol. 7
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issue 2
259-266
EN
Nanocrystalline titania particles doped with ruthenium oxide have been prepared by the homogenous hydrolysis of TiOSO4 in aqueous solutions in the presence of urea. The synthesized particles were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HRTEM), Selected Area Electron Diffraction (SAED) and Nitrogen adsorption-desorption was used for surface area (BET) and porosity determination (BJH). The photocatalytic activity of the Ru-doped titania samples were determined by photocatalytic decomposition of Orange II dye in an aqueous slurry during irradiation at 365 nm and 400 nm wavelengths. [...]
5
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Preliminary spectroscopic investigation of tacrolimus TiO2 system

88%
Todica M., Udrescu L.
Open Physics
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2011
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vol. 9
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issue 6
1536-1539
EN
The effect of air and UV exposure on the tacrolimus was observed by Raman and UV VIS spectroscopy. For moderate time exposure the chemical structure of tacrolimus is not affected. The absorption property of tacrolimus was enhanced by addition of TiO2.
6
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ESR and XRD investigation of effects induced by gamma radiation on PVA-TiO2 membranes

88%
Todica M., Stefan T., Trandafir D., Simon S.
Open Physics
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2013
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vol. 11
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issue 7
928-935
EN
The effects of gamma radiation on the local structure of PVA membranes containing TiO2 were investigated by ESR and XRD methods. An intense ESR signal is observed after irradiation at 16 KGy dose. This signal appears only for irradiated samples and it is associated with the breaking of the polymeric chain, followed by local reorganization of the polymeric segments and the apparition of the unpaired electrons and free radicals. The intensity of the signal decreases with the concentration of TiO2, indicating a shielding effect of the dopand. That the modification of local order of the polymeric chains has been modified after irradiation is confirmed by XRD method.
7
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Study of the anatase to rutile transformation kinetics of the modified TiO2

88%
Grzmil B., Gleń M., Kic B., Lubkowski K.
Polish Journal of Chemical Technology
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2013
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vol. 15
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issue 2
73-80
EN
TiO2 attracts much interest because of its many potential applications. The use of titanium dioxide strongly depends on its polymorphic form: brookite, anatase, or rutile. Only rutile and anatase play an important role in industry. Anatase as a metastable form undergoes a non-reversible transformation into rutile. Understanding the kinetics of phase transformation and the processes of crystal growth of a material is essential for controlling its structure and, thus, its specific properties. The main purpose of this paper is to explain the anatase to rutile recrystallization kinetics in the modified TiO2 calcined from industrial hydrated titanium dioxide. The apparent activation energy of anatase to rutile transformation and the average size of titanium dioxide crystallites were determined for the unmodified TiO2 and TiO2 modified with P, K, Al, B, Zn, Zr, Ce, Sn, or Sb introduced in the amount of 0.5 mol% and 1.0 mol% when recalculated for their oxides. The growth of TiO2 crystallites during calcination was strongly inhibited by P, Ce and Zr, and inhibited to a lesser degree by Al, Sn and Sb. B and Zn did not affect the investigated process and K accelerated crystallites growth. The values of apparent activation energy depending on a modifier formed a relationship: Al
8
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Influence of terbium on structure and luminescence of nanocrystalline TiO2 thin films

88%
Wojcieszak D., Kaczmarek D., Domaradzki J., Lukowiak A., Strek W.
Open Physics
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2013
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vol. 11
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issue 2
239-244
EN
In this work analysis of the structural and optical properties of TiO2 thin films doped with terbium has been described. Samples were prepared by a high energy reactive magnetron sputtering process under low pressure of oxygen plasma. X-ray diffraction results have shown that different TiO2 crystal forms have been produced, depending on the amount of Tb dopant. The undoped matrix had rutile structure with crystallites with a size of 8.7 nm, while incorporation of 0.4 at. % of Tb into the film during the sputtering process resulted in anatase structure with bigger crystallites (11.7 nm). Increasing the amount of terbium up to 2 at. % and 2.6 at. % gave rutile structure with crystallites with a size of 6.6 nm for both films. However, Raman spectroscopy has revealed that in the case of TiO2:(2 at. % Tb), except for the rutile form, the presence of fine-crystalline anatase was observed. Moreover, the lack of Raman peaks shift attests to the lack of stress in the titania lattice of all of the TiO2:Tb films. This fact indicates localization of Tb3+ ions on the surface of TiO2 nanocrystals. In the case of optical investigation, results have shown that doping with terbium has a significant influence on the properties of TiO2, but it does not decrease the high transparency of the matrix. The observed changes of the transmission characteristics were produced only due to modification of the TiO2:Tb structure. Photoluminescence measurements have shown that emission of light from TiO2:Tb films occurs when the amount of terbium is 2.6 at. %. Based on the obtained results a scheme of direct energy transfer from titanium dioxide matrix (with rutile structure) to Tb3+ ions has been proposed.
9
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Influence of ThO2 on the photocatalytic activity of TiO2

88%
Kralchevska R., Milanova M., Kovacheva P., Kolev J., Avdeev G., Todorovsky D.
Open Chemistry
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2011
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vol. 9
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issue 6
1027-1038
EN
Microcomposites consisting of TiO2 (or Ce-doped TiO2) and ThO2 (0.5–2% of the TiO2 mass) are produced by sol-gel synthesis of TiO2 in presence of ThO2. X-ray diffraction study reveals the effects of ThO2 (compared to the ThO2-free TiO2, obtained by the same method) on the anatase interplanar distances, crystallites size and phase composition. The photocatalytic tests in presence of the composites under UV irradiation reveal an increase of the Malachite Green degradation rate constant. The effect depends on the Th relative content, temperature of annealing of the catalyst and addition of other doping agent. The highest photocatalytic activity is observed for TiO2 obtained at 550°C and containing 1% ThO2. The composite exhibits activity in dark, also. The presence of Ce4+ ions is not an obligatory requirement for the realization of the ThO2 effect. The reported results suggest that the radioactivity of the Th and/or its decay products is one of the main factors responsible for the increased photocatalytic activity of TiO2. [...]
10
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Aqueous photocatalytic oxidation of prednisolone

88%
Klauson D., Pilnik-Sudareva J., Pronina N., Budarnaja O., Krichevskaya M., Käkinen A., Juganson K., Preis S.
Open Chemistry
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2013
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vol. 11
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issue 10
1620-1633
EN
The research into the aqueous photocatalytic oxidation of the anti-inflammatory drug prednisolone was undertaken with P25 titanium dioxide (Evonik) and visible light-sensitive sol-gel synthesized titania-based photocatalysts containing carbon, sulphur, and iron. Possible prednisolone photocatalytic oxidation reaction pathways were proposed based on a number of oxidation by-products determined in the present study. The prednisolone adsorption properties, effects of initial prednisolone concentration, pH, usual wastewater matrix admixtures, like carbamide and sucrose, were studied. The nontoxicity of doped catalysts towards Tetrahymena thermophila, a ciliate protozoa present in the activated sludge, indicated their lower oxidative ability compared to P25, but also implied their potential application in pre-treatment of toxic hazardous materials under VIS or solar radiation before the biological degradation stage. [...]
11
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Hydrogen gas sensors based on nanocrystalline TiO2 thin films

88%
Haidry A., Schlosser P., Durina P., Mikula M., Tomasek M., Plecenik T., Roch T., Pidik A., Stefecka M., Noskovic J., Zahoran M., Kus P., Plecenik A.
Open Physics
|
2011
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vol. 9
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issue 5
1351-1356
EN
Titanium dioxide thin films are extensively studied for applications in solid state gas sensor devices. Their gas sensing properties are strongly dependent on deposition technique, annealing temperature, film thickness and consequent properties like crystalline structure, grain size or amount of defects and impurities. In this work we report the gas sensing properties of TiO2 thin films prepared by reactive magnetron sputtering technique and subsequently annealed at temperatures 600°C and 900°C. The films were exposed to different concentrations of H2 gas up to 10 000 ppm. Their sensitivity to gas at various operating temperatures, ranging from 250°C to 450°C, was obtained by measuring their resistance.
12
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Influence of nanocrystalline structure and composition on hardness of thin films based on TiO2

88%
Kaczmarek D., Wojcieszak D., Domaradzki J., Prociow E., Placido F., Lapp S., Dylewicz R.
Open Physics
|
2011
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vol. 9
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issue 2
349-353
EN
In this work, the influence of Tb-doping on structure, and especially hardness of nanocrystalline TiO2 thin films, has been described. Thin films were formed by a high-energy reactive magnetron sputtering process in a pure oxygen atmosphere. Undoped TiO2-matrix and TiO2:Tb (2 at. % and 2.6 at. %) thin films, had rutile structure with crystallite sizes below 10 nm. The high-energy process produces nanocrystalline, homogenous films with a dense and close packed structure, that were confirmed by X-ray diffraction patterns and micrographs from a scanning electron microscope. Investigation of thin film hardness was performed with the aid of a nanoindentation technique. Results of measurements have shown that the hardness of all manufactured nanocrystalline films is above 10 GPa. In the case of undoped TiO2 matrix, the highest hardness value was obtained (14.3 GPa), while doping with terbium results in hardness decreasing down to 12.7 GPa and 10.8 GPa for TiO2:(2 at. % Tb) and TiO2:(2.6 at. % Tb) thin films, respectively. Incorporation of terbium into TiO2-matrix also allows modification of the elastic properties of the films.
13
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Photocatalytic properties of nanocrystalline TiO2 thin films doped with Tb

88%
Wojcieszak D., Kaczmarek D., Domaradzki J., Prociow E., Morawski A., Janus M.
Open Physics
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2011
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vol. 9
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issue 2
354-359
EN
In this work photocatalytic properties of TiO2 thin films doped with different amount of Tb have been described. Thin films were prepared by high energy reactive magnetron sputtering process. Comparable photocatalytic activity has been found for all doped TiO2 thin films, while different amounts of Tb dopant (0.4 and 2.6 at. %) results in either an anatase or rutile structure. It was found that the terbium dopant incorporated into TiO2 was also responsible for the amount of hydroxyl groups and water particles adsorbed on the thin film surfaces and thus photocatalytic activity was few times higher in comparison with results collected for undoped TiO2 thin films.
14
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The radioactivity and the chemical nature of additives as factors determining the photocatalytic activity of TiO2

88%
Milanova M., Kovacheva P., Kralchevska R., Kolev J., Zaharieva J., Todorovsky D.
Open Chemistry
|
2012
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vol. 10
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issue 6
1850-1858
EN
Microcomposites consisting of TiO2 and ThF4 or UO3 (0.5–2% of the TiO2 mass) are produced by sol-gel synthesis of TiO2 in presence of the respective additives. X-ray diffraction study reveals small effect of the latter on TiO2 phase composition and cell parameters and significant influence on the crystallite size and UV/Vis reflectance spectra. The photocatalytic tests in presence of TiO2-ThF4 microcomposites under UV and solar irradiation show a non-monotonic increase of the Malachite Green degradation rate constant with the increase of ThF4-content. No changes in the photocatalytic activity are observed in the presence of UO3 but the latter composites exhibit activity in darkness. The results are compared with previously reported data on the performance of TiO2-ThO2 photocatalyst with the same radioactivity and suggest that both radioactivity and the chemical nature of the dopants are responsible for the photocatalytic performance of TiO2-based composites containing radioactive substances. [...]
15
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The photocatalytic degradation of 17α-ethynylestradiol by pure and carbon nanotubes modified TiO2 under UVC illumination

88%
Kralchevska R., Milanova M., Bistan M., Pintar A., Todorovsky D.
Open Chemistry
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2012
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vol. 10
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issue 4
1137-1148
EN
Commercial product Degussa TiO2 P25, sol-gel produced TiO2 and TiO2 modified by carbon nanotubes addition (5% of the TiO2 mass) are tested as photocatalysts for the degradation of endocrine disrupting compound 17α-ethynylestradiol (1 µM aqueous solution). The molecular and crystal structure, phase composition, crystallite size, specific surface area, pore average diameter, their area and volume distribution, morphology, IR and UV/Vis spectra of the catalysts are characterized. HPLC is used for estrogen analysis. The sorption ability and photocatalytic activity (measured by degradation rate constant and percentage of the pollutant conversion) of the catalysts under UV (17 W, emission maximum at 254 nm) irradiation is determined. Full destruction of the pollutant is reached after 30 min irradiation in presence of Degussa P25. The performance of some of the catalysts is compared with literature data for their activity under 365 nm-illumination.
16
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Polymer-Titanium hybrids obtained by radical polymerization and Sol-Gel process

88%
Donescu D., Serban S., Gosa K., Petcu C.
Open Chemistry
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2005
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vol. 3
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issue 1
10-27
EN
The possibility to prepare hybrids made by poly(vinyl acetate) (PVAc), poly(methyl methacrylate) (PMMA) and/or poly(ethyl acrylate) (PEtA) with TiO2 was studied. The processes of polymer formation-radical polymerization and sol-gel process for inorganic network -were achieved simultaneously. Due to a high reactivity of titanium isopropoxide (TIP) in the sol-gel process, a complexant comonomer, allyl acetoacetate (AlAcAc), was used. Covalent bonds between polymer and inorganic chains were obtained by addition of trialkoxysilane derivates with vinyl (VTES) or methacryloyl (MPTS) groups. The presence of TIP inhibits the radical polymerization of vinyl acetate (VAc). The PVAc-TiO2 hybrids were produced by the sol-gel process of TIP in the presence of pre-obtained PVAc. Except for VTES and MPTS, trialkoxysilane derivates with methyl (MeTES), octyl (OTES) and phenyl (PTES) groups were used. The thermal stability of hybrids is strongly affected by TiO2 presence and by the type of trialkoxysilane derivates. The thermal stability of PVAc hybrids decreases in the presence of TiO2 inorganic network. The glass transition temperature of polymers increases in the presence of the inorganic network.
17
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New photocatalyst for decomposition of humic acids in photocatalysis and photo-Fenton processes

88%
Tryba B., Brożek P., Piszcz M., Morawski A.
Polish Journal of Chemical Technology
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2011
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vol. 13
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issue 4
8-14
EN
Humic acid Leonardite IHSS standard was decomposed on TiO2 and TiO2 modified by FeC2O4 via the photocatalysis and photo-Fenton processes under UV irradiation. Humic acid (HA) were favorable adsorbed on TiO2 surface and followed decomposition during UV irradiation faster on TiO2 than on the modified samples. However, when H2O2 was added to the solution, the photo-Fenton process occurred on the prepared TiO2 samples, contained iron together with photocatalysis and high acceleration of HA decomposition was observed. In this case the mineralization degree was much higher than in the applied photocatalysis only, around 75% HA (with concentration of 18 mg/L) was mineralized after 3 h of adsorption and 5 h of UV irradiation in the presence of H2O2 and modified TiO2 whereas on TiO2 mineralisation of HA occurred in around 45% only. The measured fluorescence spectra of HA solutions showed that in the presence of H2O2 polycyclic aromatics were rapidly oxidized to the lower size products such as alcohols, aldehydes, ketones and carboxylic acids, what accelerated the process of HA decomposition.
18
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Activity of phthalocyanine-sensitized TiO2-anatase in photooxidation of sulfite ions

88%
Galbas M., Banaszczyk A., Dyrda G., Szczegot K., Słota R.
|
EN
Hybrid catalysts based on the TiO2 matrix impregnated with Nd, Eu and Yb diphthalocyanines proved effective in oxidation of sulfite ions under irradiation with light from the UV-visible range. Micro- and nano-crystalline anatase powders were used in preparation of the photocatalysts, which were applied in the form of a suspension in the water phase. The reaction yield was found to depend on the phthalocyanine sensitizer used and the conditions of TiO2 impregnation. The best results were obtained when micro-anatase impregnated with Yb-diphthalocyanine was used.
19
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Influence of nanocrystalline structure and surface properties of TiO2thin films on the viability of L929 cells

88%
Osękowska M., Karuga-Kuźniewska E., Wojcieszak D., Mazur M., Poniedziałek A., Kaczmarek D., Szymonowicz M., Rybak Z.
|
EN
In this work the physicochemical and biological properties of nanocrystalline TiO2 thin films were investigated. Thin films were prepared by magnetron sputtering method. Their properties were examined by X-ray diffraction, photoelectron spectroscopy, atomic force microscopy, optical transmission method and optical profiler. Moreover, surface wettability and scratch resistance were determined. It was found that as-deposited coatings were nanocrystalline and had TiO2-anatase structure, built from crystallites in size of 24 nm. The surface of the films was homogenous, composed of closely packed grains and hydrophilic. Due to nanocrystalline structure thin films exhibited good scratch resistance. The results were correlated to the biological activity (in vitro) of thin films. Morphological changes of mouse fibroblasts (L929 cell line) after contact with the surface of TiO2 films were evaluated with the use of a contrast-phase microscope, while their viability was tested by MTT colorimetric assay. The viability of cell line upon contact with the surface of nanocrystalline TiO2 film was comparable to the control sample. L929 cells had homogenous cytoplasm and were forming a confluent monofilm, while lysis and inhibition of cell growth was not observed. Moreover, the viability in contact with surface of examined films was high. This confirms non-cytotoxic effect of TiO2 film surface on mouse fibroblasts.
20
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Photocatalytic properties of transparent TiO2 coatings doped with neodymium

88%
Wojcieszak D., Kaczmarek D., Domaradzki J., Mazur M., Morawski A. W., Janus M., Prociów E., Gemmellaro P.
Polish Journal of Chemical Technology
|
2012
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vol. 14
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issue 3
1-7
EN
In this work photocatalytic properties of TiO2 thin fi lms doped with 8.51 at. % of Nd were described. The self-cleaning phenomenon of thin fi lms was discussed together with the structural, optical and surface properties of prepared thin fi lms. Transparent coatings based on titanium dioxide were manufactured by high-energy reactive magnetron sputtering process. Incorporation of Nd during sputtering process results in amorphous behavior, without a signifi cant infl uence on transparency and colour as compared to the undoped TiO2-rutile matrix. Nevertheless, doping with neodymium doubles the photocatalytic activity of the matrix due to higher quantity of photo-generated charge carriers and more effi cient mechanism of energy transfer.
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