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

In the presence of chloroacetic acids, the photocatalytic hydrogen evolution and decomposition of the pollutants over Pt/TiO2 have been investigated. The Pt/TiO2 was prepared by photodeposition. Monochloroacetic acid and dichloroacetic acid enhance photocatalytic hydrogen generation, whereas trichloroacetic acid does not. The photocatalytic oxidation of monochloroacetic acid and dichloroacetic acid mainly produces CO2, HCl and formaldehyde, whereas the photocatalytic oxidation of trichloroacetic acid mainly produces CO2 and HCl. The effect of the concentration of monochloroacetic acid and dichloroacetic acid on the hydrogen generation rate is consistent with a Langmuir-Hinshelwood kinetic model. A possible reaction mechanism was discussed.
 ...
PMID:Photocatalytic hydrogen generation in the presence of chloroacetic acids over Pt/TiO2. 1628 14

The present paper reports photocatalytic degradation of bovine serum albumin (BSA) by TiO2 under near UV (365 nm) irradiation. Ultraviolet-Visible spectrometry, FTIR spectrometry and HPLC were used to study the degradation and characterize the final degradation products. It was found that under near UV irradiation, BSA (0.1 g x L(-1)) can be totally degraded to small fragments by TiQ2 in 5 h. Total mineralization of BSA (93.5%) is reached after reacting for 40 h. C, N and S in BSA are mineralized to give CO2, NO3- and SO4(2-). It is suggested that the degradation of BSA happens in two steps: first to small fragments, then further mineralized to small inorganic molecule. The absence of UV irradiation or TiQ2 can only lead to partial degradation of BSA (30%) in 5 h and no CO2 is observed even in longer reaction time.
 ...
PMID:[Investigation of TiO2 photocatalytic degradation of bovine serum albumin]. 1632 8

Model catalysts were prepared by deposition of size-selected Au(n) (n = 1-7) on rutile TiO2(110), and characterized by a combination of electron spectroscopy, ion scattering, temperature-programmed desorption, and pulse-dosing mass spectrometry. CO oxidation activity was found to vary strongly with deposited cluster size, with significant activity appearing at Au3. Activity is not obviously correlated with affinity for CO, or with cluster morphology, but is strongly correlated with the clusters' ability to bind oxygen (during O2 exposure) on top of the gold. The temporal dependence of CO2 evolution in reaction of O2 pre-exposed samples with CO pulses shows an interesting cluster size dependence. For Au5 and Au6, the peak CO2 production is coincident with the peak CO flux, but for Au3, Au4, and Au7, there are significant induction periods for CO2 evolution. In addition, it is observed that some of the most active cluster sizes have the slowest CO2 evolution rates. Several mechanistic scenarios capable of accounting for the observations are laid out.
 ...
PMID:Cluster size effects on CO oxidation activity, adsorbate affinity, and temporal behavior of model Au(n)/TiO2 catalysts. 1639 14

The present study concerns an experimental microkinetic approach of the photocatalytic oxidation (PCO) of isopropyl alcohol (IPA) into acetone on a pure anatase TiO2 solid according to a procedure previously developed. Mainly, the kinetic parameters of each surface elementary step of a plausible kinetic model of PCO of IPA are experimentally determined: natures and amounts of the adsorbed species and rate constants (preexponential factor and activation energy). The kinetics parameters are obtained by using experiments in the transient regime with either a FTIR or a mass spectrometer as a detector. The deep oxidation (CO2 and H2O formation) of low concentrations of organic pollutants in air is one of the interests of the PCO. For IPA, literature data strongly suggest that acetone is the single route to CO2 and H2O and this explains that the present study is dedicated to the elementary steps involving gaseous and adsorbed C3H(x)O species. The microkinetic study shows that strongly adsorbed IPA species (two species denoted nd-IPA(sads) and d-IPA(sads) due to non- and dissociative chemisorption of IPA, respectively) are involved in the PCO of IPA. A strong competitive chemisorption between IPA(sads) and a strongly adsorbed acetone species controls the high selectivity in acetone of the PCO at a high coverage of the surface by IPA(sads). The kinetic parameters of the elementary steps determined in the present study are used in part 2 to provide a modeling of macroscopic kinetic data such as the turnover frequency (TOF in s(-1)) of the PCO using IPA/O2 gas mixtures.
 ...
PMID:Experimental microkinetic approach of the photocatalytic oxidation of isopropyl alcohol on TiO2. Part 1. Surface elementary steps involving gaseous and adsorbed C3H(x)O species. 1655 71

The light-induced degradation of chlorfenapyr under UV was investigated in aqueous solutions containing TiO2 as photocatalyst. The photocatalytic degradation of chlorfenapyr followed pseudo-first-order degradation kinetics (Ct = C0e(-kt)). The study focused on the identification of possible intermediate products during the degradation, using gas chromatography mass-spectrometry (GC-MS) and 1HNMR. Six aromatic intermediates were identified by several techniques during the treatment and some of them were further confirmed by matching authentic standards. Structure analysis of the degradation products suggested two degradation pathways: (1) The aliphatic ether group was cleaved from chlorfenapyr to form pyrrole-alph-carboxylic acid, then the pyrrole group was broken to form 4-chloroglycine; (2) Chlorfenapyr was debrominated and the aliphatic ether group was cleaved from the pyrrole group, which was further broken to form 4-chlorophenylglycine. The glycine was degraded into 4-chlorobenzoic acids, which was further broken into inorganic ions and CO2.
 ...
PMID:Mechanism and pathways of chlorfenapyr photocatalytic degradation in aqueous suspension of TiO2. 1674 8

Infrared spectroscopy was used to investigate the reaction of silanes with TiO2 and Al2O3 using supercritical CO2 (Sc-CO2) as a solvent. It was found that contact of Sc-CO2 with TiO2 leads to partial removal of the water layer and to the formation of carbonate, bicarbonate, and carboxylate species on the surface. Although these carbonate species are weakly bound to the TiO2 surface and can be removed by a N2 purge, they poison the surface, resulting in a lower level of reaction of silanes with TiO2. Specifically, the amount of hexamethyldisilazane adsorbed on TiO2 is about 10% of the value obtained when the reaction is performed from the gas phase. This is not unique to TiO2, as the formation of carbonate species also occurs upon contact of Al2O3 with Sc-CO2 and this leads to a lower level of reaction with hexamethyldisilazane. This is in contrast to reactions of silanes on SiO2 where Sc-CO2 has several advantages over conventional gaseous or nonaqueous methods. As a result, caution needs to be applied when using Sc-CO2 as a solvent for silanization reactions on oxides other than SiO2.
 ...
PMID:Reaction of silanes in supercritical CO2 with TiO2 and Al2O3. 1676 4

The effects of pH and ultraviolet (UV) light with ligated formic acid on mesoporous TiO2 were characterized by transmission Fourier transform infrared (FTIR) spectroscopy and compared with adsorbed formate complexes. Surface-modified anatase thin films were prepared from acidic aqueous nanoparticulate anatase suspensions diluted with methanol and ethanol. Bands assigned to carboxylic acid groups displayed unique bonding character in the ligated formic acid on the anatase surface. For increased proton concentrations in the films, separation in -COO stretching bands (delta nu) for formic acid increased (increase in frequency for nuC=O and decrease in frequency for nuC-O). With UV exposure, surface-bound organics were rapidly removed by photocatalytic oxidation at 40 degrees C and 40% relative humidity (RH). In addition, the delta nu of the formic acid bands decreased as organics were mineralized to carbonates and CO2 with UV light. Aqueous formic acid adsorption experiments showed a distinctly different bonding environment lacking carbonate, and the delta nu for the carboxylic groups indicated a bridging bidentate coordination. The delta nu of the bands increased with increasing proton concentration, with both bands shifting to higher wavenumbers. The shifts may be ascribed to the influence of protonation on surface charge and the effect of that charge on the electronegativity of carboxylate groups bound to the surface. As alcohols are used in the mesoporous TiO2 solar cell preparation, implications of these surface modifications to dye-sensitized photovoltaics are discussed.
 ...
PMID:FTIR spectroscopy of alcohol and formate interactions with mesoporous TiO2 surfaces. 1680 May 78

Doped TiO2 samples using different preparative procedures were synthesized using either urea or thiourea leading to N- or S-doped TiO2. Photocatalytic peroxidation and oxidation (mineralization) of phosphatidylethanolamine (PE) lipid with doped TiO2 were carried out under light irradiation lambda > 410 nm. The formation of conjugated double bonds in PE molecules was followed to detect the formation of peroxy radicals (peroxidation index) under light excitation (lambda > 410 nm) when doped TiO2 was used. The kinetics of CO2 production was monitored during the mineralization of PE. Colored TiO2 powders were studied in detail by different and complementary physicochemical techniques. The band gap energies of colored TiO2 were determined by diffuse reflectance spectroscopy (DRS). The visible absorption shoulder of TiO2 was observed to follow Urbach's law. The variation of the transient decay after 354 nm laser pulse excitation does not correlate with the different N- and S-TiO2 doping levels introduced by the addition of urea or thiourea. This suggests that the states (recombination centers or traps) introduced by the doping are not effective in varying the decay kinetics within the nanosecond and microsecond time scale. Elemental analysis shows comparable amounts of S- and N-doping of TiO2 when thiourea is used as dopant. X-ray diffraction reveals no rutile in S-TiO2 samples heated to 600 degrees C, suggesting that the addition of sulfur precludes rutilization during sample crystallization. X-ray photoelectron spectroscopy (XPS) of the S-TiO2 samples confirms the preferential localization of S on the 20 topmost layers of S-TiO2 upon calcination at 500 degrees C for 2 h.
 ...
PMID:Preparation, testing and characterization of doped TiO2 active in the peroxidation of biomolecules under visible light. 1685 54

Fourier transform infrared spectroscopy has been employed to investigate the N(CH3)3 adsorption, thermal stability, and photochemical reactions on powdered TiO2. N(CH3)3 molecules are adsorbed on TiO2 without dissociation at 35 degrees C and are completely desorbed from the surface at 300 degrees C in a vacuum. The CH3 rocking frequencies of N(CH3)3 on TiO2 are affected via the interaction between N(CH3)3 and TiO2 surface OH groups. In the presence of O2, adsorbed N(CH3)3 decomposes thermally at 230 degrees C and photochemically under UV irradiation. In the latter case with comparative (16)O2 and (18)O2 studies, CO2(g), NCO(a), HCOO(a), and surface species containing C=N or NH(x) functional groups are identified to be the photoreaction products or intermediates. In the presence of (18)O2, the main formate species formed is HC(16)O(18)O(a). As H2O is added to the photoreaction system, a larger percentage of adsorbed N(CH3)3 is consumed. However, in the presence of (18)O2 and H2O, the amount of HC(16)O(18)O(a) becomes relatively small, compared to HC(16)O(16)O(a). A mechanism is invoked to explain these results. Furthermore, based on the comparison of isotopic oxygens in the formate products obtained from CH3O(a) photooxidation in (16)O2 and (18)O2, it is concluded that the N(CH3)3 photooxidation does not generate CH3O(a) in which the oxygen belongs to TiO2.
 ...
PMID:FTIR study of adsorption and surface reactions of N(CH3)3 on TiO2. 1685 35

Thin films (<10 nm) of platinum or palladium were deposited on TiO2 or GaN to form Schottky diodes. We detected and monitored the continuous electron flow across the metal-oxide interfaces of Pt/TiO2, Pd/TiO2, and Pt/GaN during the catalytic oxidation of carbon monoxide. The electron excitation and flow in the metals were due to conversion of energy released by the oxidation of carbon monoxide into the kinetic energy of free electrons in platinum and palladium. The best conversion of three electrons per four CO2 molecules was observed from 5 nm Pt/TiO2.
 ...
PMID:Continuous hot electron generation in Pt/TiO2, Pd/TiO2, and Pt/GaN catalytic nanodiodes from oxidation of carbon monoxide. 1685 34


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>