Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: KEGG:D01931 (TiO2)
11,320 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Monolayer catalysts containing binary active phases (VOx-CrOx, VOx-MoOx) were prepared by simultaneous deposition of the corresponding transition metal-oxo species on the TiO2 (anatase) surface using the equilibrium deposition filtration technique. The prepared samples contained various amounts of each transition metal but almost the same total metal loading. They were characterized by atomic absorption spectroscopy, N2 adsorption, UV-vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, and tested for the selective catalytic reduction of NO by NH3 in the temperature range 250-450 degrees C. It was found that the transition-metal ionic species used for the preparation of these catalysts compete for the same surface sites of the TiO2 carrier upon co-deposition. Small amounts of the second phase (Mo- or Cr-oxo phase) are sufficient in order to promote the catalytic activity at relatively high temperatures, in contrast to what happens in the corresponding industrial catalysts prepared by conventional methods. An electronic interaction between V- and Cr-oxo species favored at a V/Cr atomic ratio around 3 is probably responsible for the relatively high catalytic performance of the corresponding TiCrV catalyst. The activity of the studied catalysts is well correlated with the intensity of a DRS absorption band that appeared at ca. 400 nm, which is considered as a measure of the magnitude of interactions exerted between the monolayer transition metal-oxo species and the TiO2 carrier. This correlation is independent of the transition metals combination used and follows the same linear relationship found previously for single-active-phase catalysts.
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PMID:Monolayer binary active phase (Mo-V) and (Cr-V) supported on titania catalysts for the selective catalytic reduction (SCR) of NO by NH3. 1554 99

In this paper, the nano-sized SO4(2-)/TiO2 solid superacid photocatalysts have been prepared by the method of hydrothermal heating the mixed solution of Ti(S04)2 and urea, heating-decomposing, wet impregnating-calcining. The middle products and the ultimate products have been characterized by XRD, BET, FTIR, DRS and FS. The degradation of rhodamine B by photocatalyst was regarded as a model reaction. The optimum condition of preparing SO4(2-)/TiO2 photocatalysts has been chosen. The results show that hydrothermal treating the solution of Ti(SO4)2 can get the anatase nano-sized TiO2 in the weak alkalinity medium; at 300 degrees C by-products of hydrothermal reaction, such as (NH4)2SO4 and so on, can be decomposed by calcining for 4 hours, avoiding much loss of H2SO4; the most important factors that influence the photocatalystic activities of SO4(2-)/TiO2 are the concentration of SO4(2-) on TiO2 and the calcination time. SO4(2-)/TiO2 photocatalysts have the best photocatalystic activities, up to the level of P-25 photocatalyst, when the concentration of SO4(2-) on TiO2 is 11% and the calcination temperature is 450 degrees C.
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PMID:[Spectral studies on nano-sized SO4(2-)/TiO2 photocatalyst prepared by hydrothermal heating the solution of Ti(SO4)2]. 1575 70

Silica-modified titanium dioxides were prepared by a hydrothermal method and then characterized by XRD, FT-IR, XPS, TEM, and UV-visible spectroscopy. The silica-modified titanium dioxides were in anatase phase and had large surface areas. There was strong interaction between SiO2 and TiO2, and TiOSi bonds formed during the hydrothermal process. The addition of silica in TiO2 particles could effectively suppress the formation of the rutile phase and the growth of titanium dioxide crystals. DRS spectra proved an increase in the band-gap transition with the increase of silica. The silica-modified TiO2 nanoparticles exhibited better photocatalytic activity, which increased with the silica amount, in comparison with pure TiO2 nanoparticles. Due to better thermal stability, the photocatalytic activity of the silica-modified TiO2 sample held good photocatalytic activity even after calcined at 1273 K.
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PMID:Hydrothermal synthesis, characterization, and photocatalytic performance of silica-modified titanium dioxide nanoparticles. 1592 73

Boron doped CeO2/TiO2 mixed oxides photocatalysts were prepared by adding boric acid and cerous nitrate during the hydrolyzation of titanium trichloride and tetrabutyl titanate. XRD, UV-Vis DRS and XPS techniques were used to characterize the crystalline structure, light absorbing ability and the chemical state of Boron element in the photocatalyst sample. The photocatalytic activities were evaluated by monitoring the degradation of acid red B under UV irradiation. These results indicate that the wavelengths at adsorbing edge are affected by the content of cerous nitrate and the maximum absorption wavelength is about 481 nm when the mole ratio of Ce/Ti is 1.0. For higher dosage of Cerium, the absorbance edge shifts to blue slightly. The prepared photocatalyst is composed of anatase TiO2 and cubic CeO2 when calcined at 500 degrees C. An increase in the calcination temperature transforms the crystalline structure of the titanium oxides from anatase to rutile, and has no obvious influence on crystalline structure of CeO2 but crystallites growth up. The absorbance edge decreases drastically with the increase of calcination temperature. With a view to the stability of photocatalyst and utilization of sun energy, 500 degrees C of calcination temperature is recommended. The XP spectrum for B1s exhibits that only a few boron ions dope into titania and ceria matrix, others exist in B2O3. The photocatalytic activity increases with increase of cerous nitrate dosage, and decreases drastically due to higher dosage (the mol ratio of Ce/Ti > 0.5). After 10 min UV irradiation, 96% of acid red B is degraded completely over photocatalyst under optimum reaction condition.
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PMID:[Preparation and photocatalytic activity of boron doped CeO2/TiO2 mixed oxides]. 1688 3

Nitrogen doped titania was prepared by low temperature sol-gel method using titanium precursor and nitrogen containing bases like triethylamine and tetramethyl ammonium hydroxide compounds. The materials were characterized by XRD, BET, SEM, XPS, DRS-UV, and FT-IR techniques. DRS-UV study substantially indicates shift of the absorption edge of TiO2 to lower energy region. The phase composition, crystallinity, specific surface area, and visible light activity of nitrogen doped titania depend upon the preparation conditions. Photocatalytic degradation of bisphenol-A in aqueous medium was investigated by TiO2 and nitrogen doped TiO2 under visible light irradiation in a batch photocatalytic reactor. The results indicate higher visible light activity for nitrogen doped TiO2 than commercial TiO2 (Degussa P25) for bisphenol-A degradation. The influence of various parameters such as initial concentration of bisphenol-A, catalyst loading and pH was examined for maximum degradation efficiency.
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PMID:Visible light active photocatalytic degradation of bisphenol-A using nitrogen doped TiO2. 1703 63

In the present work, a TiO2/activated carbon (AC) photocatalyst with high activity and easy separation was prepared using a hydrothermal method. Phenol, methyl orange (MO) and Cr(VI) were used as target pollutants to test the activity and decantability. SEM, XRD, FTIR, diffuse reflectance spectra (UV/DRS) and N2 adsorption isotherms were used to characterize the crystalline and electronic structure. Results show that the AC composite has a significant effect on the TiO2 activity. With suitable AC content, the TiO2/xAC catalysts prepared were much more active. The TiO2/5AC catalyst exhibited easy separation and less deactivation after several runs, and was less sensitive to pH changes. UV/DRS revealed that no electronic bandgap changes in TiO2 occurred on addition of the AC. SEM and XRD results suggest that better TiO2 distribution can be achieved when an optimal AC content is used. A Ti-O-C bond was formed and a slight conjugation effect appeared between the AC bulk and TiO2. The advantages of the obtained TiO2/5AC catalyst revealed its great practical potential in wastewater treatment.
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PMID:A TiO2/AC composite photocatalyst with high activity and easy separation prepared by a hydrothermal method. 1704 60

Ni-doped TiO2 photocatalysts were prepared by low temperature combustion synthesis and some properties, such as optical absorption, crystal type, grain size distribution and chemistry transformation during temperature rising were characterized by UV-Vis DRS, X-ray diffraction (XRD), laser light dispersion grain size measurement machine and TG-DSC respectively. The photocatalytic activities of the prepared photocatalysts under visible light irradiation were evaluated by monitoring the degradation of methylene blue dye, a probe pollutant. The results indicate that the Ni-doped TiO2 photocatalysts prepared by low temperature combustion synthesis shift the optical absorption threshold to visible light, the band gap of 0.4 Ni-TiO2 (atomic ratio) is 2.3 eV, which corresponds to a 564 nm threshold in the visible light range. The crystal type of photocatalyst is anatase TiO2 and the content of NiTiO3 rise with the increase of Ni dopant. The grain size of photocatalyst distributes from 50 to 150nm, which account for 96.9% of entire quantity. During temperature rising, the TiO2 phase in photocatalyst transforms from amorphous structure to anatase and NiTiO3 crystallites appear at 445.2 degrees C. After 150 min visible light irradiation, 93.9% of methylene blue dye are degraded over 0.4 Ni-TiO2 photocatalyst. The photocatalytic activity of Ni doped TiO2 is higher than that of P25 under identical conditions.
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PMID:[Characterization and photocatalytic activity of Ni-doped tiO2 nano photocatalysts prepared by low temperature combustion synthesis]. 1732 17

TiO2 /SiO2 were prepared by surface reaction of silica with an acetone solution of Ti(i-OC3H7)nCl(4-n), where n = 0-2. Results of XRD, Raman and UV-Vis DRS showed that two types of Ti species, small particles of anatase-type TiO2 and non-crystalline TiO(x) species, are molecularly dispersed on the silica surface. Relative to the TiO2 bulk, a blue-shift in the bandgap adsorption edge of TiO2/SiO2 was observed due to the quantum size effects. The bandgap energy (E(g)) of TiO2/SiO2 is 3.96 eV. When M(Pd, Cu, Ni) is deposited on TiO2/SiO2, the adsorption spectra extend to visible light region and the bandgap adsorption edge red shifts with respect to TiO2/SiO2. Compared with that of Pd, the deposition of Cu and Ni on TiO2/SiO2 has more effects on LMCT transition (O2- --> Ti4+) of Ti atoms. And the bandgap energy of Cu-TiO2 /SiO2 decreases to 3.69 eV. Similarly, the photon adsorption property for visible light can be improved relatively by the incorporation of MoO3 on TiO2/SiO2, At higher MoO3 loadings, the Mo-O-Ti coupled structure can be formed through the interaction between MoO3 and TiO2, which made the bandgap energy decrease to 3.81 eV.
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PMID:[The study on DRS and Raman spectroscopy of surface modified TiO2/SiO2]. 1760 83

S-doped TiO2 photocatalyst with high visible light activity was prepared by acid catalyzed hydrolysis method using thiourea (TU) as sulfur source. The catalyst was characterized by DRS, XPS, XRD, FTIR, SEM and N2 adsorption. It was found that cation S6+ was homogeneously incorporated into the bulk phase of TiO2 and substitutes for some of the lattice titanium (Ti4+). Doped S can form a new band above the valence band and narrow the band-gap of the photocatalyst, giving rise to a second absorption edge in the visible light region. The activity of the catalyst was examined by photodegradation of phenol in aqueous solution under both artificial visible light and solar light irradiation. The activity of catalyst was found to be dependent on the doping amount of S and the maximum activity was observed when the catalyst was obtained by calcinated at 600 degrees C with the mass ratio of TU/TiO2=1. Too much of new-generated band-gap structures due to higher S-doping could act as recombination centers for electron-hole pairs. Catalyst with optimum S-doping exhibited the highest activity under both artificial light and solar irradiation for phenol degradation. In addition, doped S also beneficial for the better dispersion, large S(BET) and phase transformation retardation of TiO2.
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PMID:A visible light response TiO2 photocatalyst realized by cationic S-doping and its application for phenol degradation. 1767 65

The photocatalytic degradation and mineralization of isoproturon herbicide was investigated in aqueous solution containing TiO2 over H-mordenite (H-MOR) photocatalysts under solar light. The catalysts are characterized by X-ray diffraction (XRD), UV-Vis diffused reflectance spectra (UV-Vis DRS), Fourier transform-infra red spectra (FT-IR) and scanning electron microscopy (SEM) techniques. The effect of TiO2, H-MOR support and different wt% of TiO2 over the support on the photocatalytic degradation and influence of parameters such as TiO2 loading, catalyst amount, pH and initial concentration of isoproturon on degradation are evaluated. 15wt% TiO2/H-MOR composite is found to be optimum. The degradation reaction follows pseudo-first order kinetics and is discussed in terms of Langmuir-Hinshelwood (L-H) kinetic model. The extent of isoproturon mineralization studied with chemical oxygen demand (COD) and total organic carbon (TOC) measurements and approximately 80% mineralization occurred in 5h. A plausible mechanism is proposed based on the intermediates identified by liquid chromatography-mass spectroscopy (LC-MS).
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PMID:Solar photocatalytic degradation of isoproturon over TiO2/H-MOR composite systems. 1843 2


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