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1.
Po-Kai Chiu Chao-Te Lee Donyau Chiang Wen-Hao Cho Chien-Nan Hsiao Yi-Yan Chen Bo-Ming Huang Jer-Ren Yang 《Nanoscale research letters》2014,9(1):35
Conductive and transparent multilayer thin films consisting of three alternating layers (TiO2/Ag/SiO2, TAS) have been fabricated for applications as transparent conducting oxides. Metal oxide and metal layers were prepared by electron-beam evaporation with ion-assisted deposition, and the optical and electrical properties of the resulting films as well as their energy bounding characteristics and microstructures were carefully investigated. The optical properties of the obtained TAS material were compared with those of well-known transparent metal oxide glasses such as ZnO/Ag/ZnO, TiO2/Ag/TiO2, ZnO/Cu/ZnO, and ZnO/Al/ZnO. The weathering resistance of the TAS film was improved by using a protective SiO2 film as the uppermost layer. The transmittance spectra and sheet resistance of the material were carefully measured and analyzed as a function of the layer thickness. By properly adjusting the thickness of the metal and dielectric films, a low sheet resistance of 6.5 ohm/sq and a high average transmittance of over 89% in the 400 to 700 nm wavelength regions were achieved. We found that the Ag layer played a significant role in determining the optical and electrical properties of this film. 相似文献
2.
《塑料、橡胶和复合材料》2013,42(4):148-154
AbstractIn order to enhance the compatibility of TiO2 nanoparticles in poly(butyl acrylate) (PBA) matrix, surface modification of TiO2 was conducted using 3-methacryloxypropyl-trimethoxysilane (MPS). To improve the effect of surface modification, TiO2 was predispersed in ethanol via ultrasonic waves. The process was investigated in detail to obtain the optimum condition of ultrasonic dispersion. The dispersion of TiO2 in ethanol was evaluated via sedimentation rate. Fourier transform infrared spectroscopy and thermogravimetric analysis were performed to investigate the effect of surface modification. It was found that the organic functional groups of MPS had been successfully grafted onto the surface of TiO2 nanoparticles. Finally, both neat PBA film and TiO2/PBA composite film were prepared and characterised. The modified TiO2 presented good compatibility in PBA matrix. 相似文献
3.
TiO2 supported on SiO2 surface is effective on the recovery of photocatalyst, morphological control, and coating on the substrate. Furthermore,
it shows much higher photocatalytic activity than pure TiO2. The silica support is quite influential on the surface properties of TiO2 supported on SiO2. The enhanced photocatalytic activity of TiO2–SiO2 could be explained by the effects of surface area, adsorption, band-gap energy and local structure. However, it is difficult
to say which one is the most important factor responsible for the photocatalytic property of TiO2–SiO2. For example, the reduction of particle size could effect on both of the surface area and band-gap energy. And, Ti–O–Si bonds
could modify the band-gap energy and local structure. Therefore, the photocatalytic properties of TiO2–SiO2 should be expressed by sum of many factors such as surface area, adsorption, band-gap energy and local structure. 相似文献
4.
Ali İmran Vaizoğullar 《Chemical Engineering Communications》2017,204(6):689-697
In this study, TiO2, ZnO, TiO2/ZnO (Ti/Zn), and TiO2/ZnO/Sep (Ti/Zn/Sep) catalysts have been synthesized using sol–gel and chemical precipitation method. Their photocatalytic performances have been compared using Flumequine (FLQ) antibiotic. X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), scanning electron microscopy (SEM), N2-adsorption, and the determination of a zero point charge has been used to characterize the synthesized catalysts. The degradation studies showed that the catalytic efficiency of Ti/Zn/Sep is higher than that for other catalysts. The operational parameters such as pH, initial FLQ concentration, and catalyst dosage were evaluated. UV–vis and high-resolution mass spectroscopy (HRMS) analyses were used to determine the degradation efficiency and products. ZnO played a major role in the FLQ degradation process, and sepiolite contributed to adsorption of FLQ on the catalyst surface enormously. The catalysts exhibited 11%, 23%, 63%, and 85% degradation efficiency for ZnO, TiO2, Ti/Zn, and Ti/Zn/Sep in the decomposition of FLQ, respectively. 相似文献
5.
In H2 TPD from Ru/SiO2, two desorption peaks were observed. Both exchanged H for D in sequential dosing experiments. These hydrogen adsorption states were also found for Ru-Cu/SiO2, along with another, higher temperature state at 400–500 K. This last state was neither exchangeable with nor replaceable by deuterium subsequently dosed at 150 K. The three chemisorption states are attributed to hydrogen held at the interface between Ru and SiO2 (< 300 K), adsorbed on Ru particles (310–380 K), and held at the Ru-Cu interface (> 400 K). 相似文献
6.
Using TiO2 as carrier, CuO/TiO2 catalysts with different CuO loading were prepared by the impregnation method. The catalytic activities in NO+CO reaction
were examined with a micro-reactor gas chromatography reaction system and the methods of TPR, XPS and NO-TPD. It was found
that the catalytic activities were affected by pretreatment atmosphere, i.e. H2 atmosphere > reduction–reoxidation > 10%CO/He > reaction gas (fresh sample). NO decomposition was better by low-valence Cu
species than by high-valence Cu species, i.e. Cu0>Cu+>Cu2+. The XPS results indicated that Cu species on CuO/TiO2 were Cu0, Cu+, normal Cu2+(Cu2+(I)) and chain-structured Cu2+(Cu2+(II)) as –Cu–O–Ti–O–. The activities of Cu2+(II) were much higher than that of Cu2+(I), but both species were very unstable in the reaction atmosphere and easily reduced by CO, which accounted for the variable
activities of fresh catalysts with increasing reaction temperature. In NO+CO reaction, the redox process was a cycle of Cu+–Cu2+(I) at low reaction temperature but was a cycle of Cu0–Cu+ at high reaction temperature. As shown by NO-TPD, high catalytic activities could be attributed to the following factors,
e.g. oxygen caves on the catalyst’s surface after pretreatment with H2 and reduction–reoxidation, formation of Cu0 after pretreatment with H2, and increment of Cu species dispersion and formation of Cu2+(II) after pretreatment with reduction–reoxidation. 相似文献
7.
Titania-supported Au catalysts were given both low temperature reduction and high temperature reduction at 473 and 773 K, respectively, and their adsorption and catalytic properties were compared to identically pretreated Pt/TiO2 catalysts and pure TiO2 samples as well as Au/SiO2 catalysts. This was done to determine whether a reaction model proposed for methanol synthesis over metals dispersed on Zn, Sr and Th oxides could also explain the high activities observed in hydrogenation reactions over MSI (Metal-Support Interaction) catalysts such as Pt/TiO2. This model invokes O vacancies on the oxide support surface, formed by electron transfer from the oxide to the metal across Schottky junctions established at the metal-support interface, as the active sites in this reaction. The similar work functions of Pt and Au should establish similar vacancy concentrations, and O2 chemisorption indicated their presence. However, these Au catalysts were completely inactive for CO and acetone hydrogenation, and ethylene hydrogenation rates were lower on the supported Au catalysts than on the supports alone. Consequently, this model cannot explain the high rate of the two former reactions over TiO2-supported Pt although it does not contradict models invoking specialinterfacial sites. 相似文献
8.
Shengying Li Shihong Xu Lijun He Fei Xu Yonghong Wang Li Zhang 《Polymer-Plastics Technology and Engineering》2013,52(4):400-406
The photocatalytic degradation of polyethylene (PE) plastic was carried out directly under the sunlight irradiation with polypyrrole/TiO2 (PPy/TiO2) nanocomposite as photocatalyst, which prepared by sol-gel and emulsion polymerization methods. The photocatalytic degradation efficiency was determined by weight loss monitoring, gel permeation chromatography (GPC), atomic force microscopic (AFM) and FT-IR analysis. The photocatalytic degradations of PE plastic with pure TiO2 and PPy were also investigated and compared with that of PPy/TiO2. It was noticed that irradiating the PE plastic for 240 h by sunlight reduced its weight up to 35.4% and 54.4% of M w, respectively. The AFM images showed the formation of cavities on PE plastic surface. FT–IR spectroscopic studies indicated that a strong interaction existed between the interface of PE and PPy/TiO2 and caused the degradation of PE. The photocatalytic degradation mechanism was also discussed briefly. 相似文献
9.
Jesús I Pe?a-Flores Abraham F Palomec-Garfias César Márquez-Beltrán Enrique Sánchez-Mora Estela Gómez-Barojas Felipe Pérez-Rodríguez 《Nanoscale research letters》2014,9(1):499
The effect of Fe ion concentration on the morphological, structural, and optical properties of TiO2 films supported on silica (SiO2) opals has been studied. TiO2:Fe2O3 films were prepared by the sol-gel method in combination with a vertical dip coating procedure; precursor solutions of Ti and Fe were deposited on a monolayer of SiO2 opals previously deposited on a glass substrate by the same procedure. After the dip coating process has been carried out, the samples were thermally treated to obtain the TiO2:Fe2O3/SiO2 composites at the Fe ion concentrations of 1, 3, and 5 wt%. Scanning electron microscopy (SEM) micrographs show the formation of colloidal silica microspheres of about 50 nm diameter autoensembled in a hexagonal close-packed fashion. Although the X-ray diffractograms show no significant effect of Fe ion concentration on the crystal structure of TiO2, the μ-Raman and reflectance spectra do show that the intensity of a phonon vibration mode and the energy bandgap of TiO2 decrease as the Fe+3 ion concentration increases. 相似文献
10.
Sigl Michael Bradford Michael C.J. Knözinger Helmut Vannice M. Albert 《Topics in Catalysis》1999,8(3-4):211-222
The reforming of methane with carbon dioxide over rhodium dispersed on silica, Rh/SiO2, and vanadia-promoted silica, Rh/VOx/SiO2, was studied by kinetic test reactions under differential conditions in a temperature range from 723 to 773 K. Transmission
infrared spectroscopy was applied to observe the interaction of CO2 with the catalysts and the formation of surface intermediates during the CO2–CH4 reforming reaction. To analyze carbon deposition XP spectroscopy and TPO was carried out. It has been shown that the promotion
of Rh/SiO2 catalysts with vanadium oxide enhances the catalytic activity for CO2 reforming of methane and decreases the deactivation by carbon deposition. This is attributed to the formation of a partial
VOx overlayer on the Rh surface, which reduces the size of accessible ensembles of Rh atoms required for coke formation and creates
new sites at the Rh–VOx interfacial region that are considered to be active sites for the activation/dissociation of carbon dioxide.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
11.
Meldola blue immobilized on a new SiO2/TiO2/graphite composite was applied in the electrocatalytic oxidation of NADH. The materials were prepared by the sol-gel processing method and characterized by several techniques including scanning electronic microscopy coupled to energy dispersive spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electronic microscopy (HRTEM). Si and Ti mapping profiles on the surface showed a homogeneous distribution of the components. Ti2p binding energy peaks indicate that the formation of Si-O-Ti linkage is presumably the responsible for the high rigidity of the matrices. The good electrical conductivity presented by the composites (5 and 11 S cm−1) can be related to a homogeneous distribution of graphite particles observed by TEM. After the materials characterization, a SiO2/TiO2/graphite electrode was prepared and some chemical modifications were performed on its surface to promote the adsorption of meldola blue. The resulting system presented electrocatalytic properties toward the oxidation of NADH, decreasing the oxidation potential to −120 mV. The proposed sensor showed a wide linear response range from 0.018 to 7.29 mmol l−1 and limit of detection of 0.008 mmol l−1. SiO2/TiO2/graphite has shown to be a promising material to be used as a suitable support in the construction of new electrochemical sensors. 相似文献
12.
C.H. Rochester 《Catalysis Letters》1998,52(1-2):121-121
This note rectifies serious omissions from the references included in a recent paper by Fujitani et al. concerned with methanol
synthesis over Cu/SiO2 containing ZnO.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
13.
The effects of superficial gas velocity (Ug), wavelength and intensity of ultraviolet (UV) light, oxygen and H2O concentration on the photocatalytic degradation of TCE (Trichloroethylene) over TiO2/SiO2 catalyst have been determined in an annulus fluidized bed photoreactor. The key factor in determining the performance of
the annulus fluidized bed photoreactor is found to be an optimum superficial gas velocity (Ug) that provides the optimum UV
lighttransmit through the proper size of bubbles in the photoreactor. The degradation efficiency of TCE increases with light
intensity but decreases with wavelength of the UV light and H2O concentration in the fluidized bed of TiO2/silica-gel photocatalyst. The optimum concentration of O2 for TCE degradation is found to be approximately 10%. The annulus fluidized bed photoreactor is an effective tool for high
TCE degradation with efficient utilization of photon energy.
This paper is dedicated to Professor Dong Sup Doh on the occasion of his retirement from Korea University. 相似文献
14.
Neelam Jagtap Shubhangi B. Umbarkar Pierre Miquel Pascal Granger Mohan K. Dongare 《Applied catalysis. B, Environmental》2009,90(3-4):416-425
Ag/Al2O3 catalysts with 1 wt% SiO2 or TiO2 doping in alumina support have been prepared by wet impregnation method and tested for sulphur tolerance during the selective catalytic reduction (SCR) of NOx using propene under lean conditions. Ag/Al2O3 showed 44% NOx conversion at 623 K, which was drastically reduced to 21% when exposed to 20 ppm SO2. When Al2O3 support in Ag/Al2O3 was doped with 1 wt% SiO2 or TiO2 the NOx conversion remained constant in presence of SO2 showing the improved sulphur tolerance of these catalysts. Subsequent water addition does not induce significant deactivation. On the contrary, a slight promotional effect on the activity of NO conversion to nitrogen is observed after Si and Ti incorporation. FTIR study showed the sulphation of silver and aluminum sites of Ag/Al2O3 catalysts resulting in the decrease in the formation of reactive intermediate species such as –NCO, which in turn decreases NOx conversion to N2. In the case of Ag/Al2O3 doped with SiO2 or TiO2, formation of silver sulphate and aluminum sulphate was drastically reduced, which was evident in FTIR resulting in remarkable improvement in the sulphur tolerance of Ag/Al2O3 catalyst. These catalysts before and after the reaction have been characterized with various techniques (XRD, BET surface area, transmittance FTIR and pyridine adsorption) for physico-chemical properties. 相似文献
15.
The V2O5 catalysts supported on TiO2–SiO2–MoO3 (TSM) prepared by the coprecipitation method were investigated for the selective catalytic reduction (SCR) of NO by NH3 at low temperatures. The V2O5/TSM catalyst with 7–13 wt% SiO2 was found to exhibit a superior SCR activity and a good sulfur tolerance at low temperatures (<250 °C). The presence of highly
active polymeric vanadates formed by the incorporation of MoO3 to TiO2–SiO2 and superior redox properties seems to enhance SCR activity, and furthermore the very lower SO2 oxidation activity due to the higher acidity leads to the remarkable improvement of sulfur tolerance. 相似文献
16.
During room‐temperature transient experiments, acetic acid decomposes photocatalytically on TiO2 in an inert atmosphere by two parallel pathways. One pathway forms CO2 and C2H6 in a 2:1 ratio, and H2O forms with lattice oxygen that was extracted from the surface. The other pathway forms CO2 and CH4 in a 1:1 ratio.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
17.
First principles calculations within density functional theory have been carried out to investigate the adsorptions of SOx (x?=?1, 2) molecules on TiO2/MoS2 nanocomposites in order to fully discover the gas sensing capabilities of TiO2/MoS2 composite systems. The van der Waals interactions were included to obtain the most stable geometrical structures of TiO2/MoS2 nanocomposites with adsorbed SOx molecules. SOx molecules preferentially interact with the doped nitrogen and fivefold coordinated titanium sites of the TiO2 anatase nanoparticles because of their higher activities in comparison with the other sites. The results presented include structural parameters such as bond lengths and bond angles and energetics of the systems such as adsorption energies. The variation of electronic structures are discussed in view of the density of states and molecular orbitals of the SOx molecules adsorbed on the nanocomposites. The results show that the adsorption of the SOx molecule on the N-doped TiO2/MoS2 nanocomposite is energetically more favorable than the adsorption on the undoped one, implying that the nitrogen doping helps to strengthen the interaction of SOx molecules with TiO2/MoS2 nanocomposites. These calculated results thus provide a theoretical basis for the potential applications of TiO2/MoS2 nanocomposites in the removal and sensing of harmful SOx molecules. 相似文献
18.
Preparation of TiO2/SiO2 multilayer flakes and their application to decorative powders were investigated. In contrast to conventional products prepared through the multicoating of core platelets, the coreless TiO2/SiO2 multilayer flakes were prepared by detaching multilayer films from their substrates. These flakes exhibited structural colors, when the optical path length of both the TiO2 and SiO2 layers are adjusted to be one fourth of the wavelength of visible light. A multicoating of more than five layers resulted in the propagation of cracks, which prevented the preparation of thick flakes. Paint films fabricated using the multilayer flakes and acrylic resins showed reflectance spectra that were comparable with those obtained for multicoatings on substrates. 相似文献
19.
Mo2C prepared on SiO2 was found to be an effective catalyst for the dehydrogenation of ethane to produce ethylene in the presence of CO2. The selectivity to ethylene at 850–923 K was 90–95% at an ethane conversion of 8–30%. With the increase of the temperature
the dry reforming of ethane became also a significant process. It is assumed that the Mo oxycarbide formed in the reaction
between CO2 and Mo2C plays an important role in the activation of ethane.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
20.
J. Godnjavec J. Zabret B. Znoj S. Skale N. Veronovski P. Venturini 《Progress in Organic Coatings》2014
Surface modification and characterization of TiO2 nanoparticles as an additive in a polyacrylic clear coating were investigated. For the improvement of nanoparticles dispersion and the decreasing of photocatalytic activity, the surface of nanoparticles was modified with binary SiO2/Al2O3. The surface treatment of TiO2 nanoparticles was characterized with FTIR. Microstructural analysis was done by AFM. The size, particle size distribution and zeta potential of TiO2 nanoparticles in water dispersion was measured by DLS method. For the evaluation of particle size and the stability of nanoparticles in water dispersions with higher solid content the electroacoustic spectroscopy was made. To determine the applicability and evaluate the transmittance of the nano-TiO2 composite coatings UV–VIS spectroscopy in the wavelength range of 200–800 nm was employed. The results showed that surface treatment of TiO2 nanoparticles with SiO2/Al2O3 improves nanoparticles dispersion and UV protection of the clear polyacrylic composite coating. 相似文献