Comparative Photocatalytic Study of TiO2 Coatings on Al Fiber

2006 ◽  
Vol 11-12 ◽  
pp. 15-18 ◽  
Author(s):  
L. Luo ◽  
Lei Miao ◽  
Sakae Tanemura ◽  
Masaki Tanemura ◽  
Miwa Kawasaki
Keyword(s):  
Anatase Tio2 ◽  
Tio2 Coating ◽  
Crystal Quality ◽  
Oh Radicals ◽  
Nox Removal ◽  
Tio2 Layer ◽  
Photocatalytic Ability ◽  
Good Crystal Quality ◽  
Photocatalytic Effect ◽  
Ti Content

The photocatalytic effects of 4 samples, which TiO2 layer uniformly coated on Al fiber, are evaluated by NOx removal. An anatase TiO2 coating with good crystal quality and high Ti content exhibits the best photocatalytic effect on NOx removal. It is coincidence with the results of XRD, XPS results for 4 samples. The photocatalytic ability is enhanced by the introduction of H2O2 due to the formation of large amount OH radicals.

scholarly journals Modelling Atmospheric Mineral Aerosol Chemistry to Predict Heterogeneous Photooxidation of SO<sub>2</sub>

2017 ◽  
Author(s):  
Zechen Yu ◽  
Myoseon Jang ◽  
Jiyeon Park
Keyword(s):  
Mineral Dust ◽  
Uv Light ◽  
Full Range ◽  
Saharan Dust ◽  
Dust Particles ◽  
Oh Radicals ◽  
Desorption Kinetics ◽  
So2 Oxidation ◽  
Photocatalytic Ability ◽  
Sulfate Formation

Abstract. The photocatalytic ability of airborne mineral dust particles is known to heterogeneously promote SO2 oxidation, but prediction of this phenomenon is not fully taken into account by current models. In this study, the Atmospheric Mineral Aerosol Reaction (AMAR) model was developed to capture the influence of air-suspended mineral dust particles on sulfate formation in various environments. In the model, SO2 oxidation proceeds in three phases including the gas phase, the inorganic-salted aqueous phase (non-dust phase), and the dust phase. Dust chemistry is described as the adsorption-desorption kinetics (gas-particle partitioning) of SO2 and NOx. The reaction of adsorbed SO2 on dust particles occurs via two major paths: autoxidation of SO2 in open air and photocatalytic mechanisms under UV light. The kinetic mechanism of autoxidation was first leveraged using controlled indoor chamber data in the presence of Arizona Test Dust (ATD) particles without UV light, and then extended to photochemistry. With UV light, SO2 photooxidation was promoted by surface oxidants (OH radicals) that are generated via the photocatalysis of semiconducting metal oxides (electron–hole theory) of ATD particles. This photocatalytic rate constant was derived from the integration of the combinational product of the dust absorbance spectrum and wave-dependent actinic flux for the full range of wavelengths of the light source. The predicted concentrations of sulfate and nitrate using the AMAR model agreed well with outdoor chamber data that were produced under natural sunlight. For seven consecutive hours of photooxidation of SO2 in an outdoor chamber, dust chemistry at the low NOx level was attributed to 70 % of total sulfate (60 ppb SO2, 290 μg m−3 ATD, and NOx less than 5 ppb). At high NOx (> 50 ppb of NOx with low hydrocarbons), sulfate formation was also greatly promoted by dust chemistry, but it was significantly suppressed by the competition between NO2 and SO2 that both consume the dust-surface oxidants (OH radicals or ozone). The AMAR model, derived in this study with ATD particles, will provide a platform for predicting sulfate formation in the presence of authentic dust particles (e.g. Gobi and Saharan dust).

Structural and morphological characterization of anatase TiO2 coating on χ-Alumina scale fiber fabricated by sol–gel dip-coating method

2004 ◽  
Vol 271 (1-2) ◽  
pp. 245-251 ◽  
Author(s):  
Hue Thi Nguyen ◽  
Lei Miao ◽  
Sakae Tanemura ◽  
Masaki Tanemura ◽  
Shoichi Toh ◽  
...  
Keyword(s):  
Sol Gel ◽  
Alumina Scale ◽  
Dip Coating ◽  
Morphological Characterization ◽  
Anatase Tio2 ◽  
Tio2 Coating ◽  
Coating Method ◽  
Dip Coating Method

scholarly journals The role of the concentration profile of titanium oxide on the electrochemical behavior of RuO2-TiO2 coatings obtained by the sol-gel procedure

2003 ◽  
Vol 68 (12) ◽  
pp. 979-988 ◽  
Author(s):  
Vladimir Panic ◽  
Aleksandar Dekanski ◽  
Vesna Miskovic-Stankovic ◽  
Slobodan Milonjic ◽  
Branislav Nikolic
Keyword(s):  
Electrochemical Behavior ◽  
High Frequency ◽  
Electrochemical Impedance ◽  
Sol Gel ◽  
Tio2 Coating ◽  
Tio2 Layer ◽  
Low Frequencies ◽  
Tio2 Coatings ◽  
Overall Resistance

In order to understand the role of TiO2 in the deactivation mechanism of an active RuO2?TiO2 coating, an additional TiO2 layer was introduced in the support coating interphase of regular Ti//[RuO2?TiO2 anode in one case and on the surface of the coating in the other. The electrochemical behavior of these, with TiO2 enriched, anodes was compared with the behavior of anodes with regular RuO2?TiO2 coatings, which were subjected to an accelerated stability test. A high-frequency semicircle in the complex plane plot obtained by electrochemical impedance spectroscopy, for a regular RuO2?TiO2 coating corresponds to TiO2 enrichment in the coating as a consequence of anode corrosion. In the case of the coatings with additional TiO2 layers, a high-frequency semicircle was not observed. The additional TiO2 layers increase the coating overall resistance and influence the coating impedance behavior at low frequencies. Similar equivalent electrical circuits were used to analyze the impedance behavior of coatings having an additional TiO2 layer at different position within RuO2?TiO2 coating.

Aspects of Crystal Quality of Si (100) Films Grown by Molecular Beam Epitaxy

1991 ◽  
Vol 220 ◽  
Author(s):  
W. -X. Ni ◽  
A. Henry ◽  
J. O. Ekberg ◽  
G. V. Hansson
Keyword(s):  
Molecular Beam Epitaxy ◽  
Mechanical Stress ◽  
Chemical Etching ◽  
Molecular Beam ◽  
Crystal Quality ◽  
Radiant Heating ◽  
Resistive Heating ◽  
Good Crystal Quality ◽  
Resistively Heated

ABSTRACTSilicon layers grown by molecular beam epitaxy, using both direct resistive heating and indirect radiant heating of the substrate, have been evaluated by photoluminescence measurements, diode I-V characterization, and chemical etching tests. The results show that large densities of defects could be introduced when resistively heated substrates were experiencing thermo-mechanical stress. Films with good crystal quality were grown using a carefully designed radiant type heater.

scholarly journals Modeling atmospheric mineral aerosol chemistry to predict heterogeneous photooxidation of SO<sub>2</sub>

2017 ◽  
Vol 17 (16) ◽  
pp. 10001-10017 ◽  
Author(s):  
Zechen Yu ◽  
Myoseon Jang ◽  
Jiyeon Park
Keyword(s):  
Gas Phase ◽  
Mineral Dust ◽  
Uv Light ◽  
Full Range ◽  
Dust Particles ◽  
Oh Radicals ◽  
Desorption Kinetics ◽  
So2 Oxidation ◽  
Photocatalytic Ability ◽  
Sulfate Formation

Abstract. The photocatalytic ability of airborne mineral dust particles is known to heterogeneously promote SO2 oxidation, but prediction of this phenomenon is not fully taken into account by current models. In this study, the Atmospheric Mineral Aerosol Reaction (AMAR) model was developed to capture the influence of air-suspended mineral dust particles on sulfate formation in various environments. In the model, SO2 oxidation proceeds in three phases including the gas phase, the inorganic-salted aqueous phase (non-dust phase), and the dust phase. Dust chemistry is described as the absorption–desorption kinetics of SO2 and NOx (partitioning between the gas phase and the multilayer coated dust). The reaction of absorbed SO2 on dust particles occurs via two major paths: autoxidation of SO2 in open air and photocatalytic mechanisms under UV light. The kinetic mechanism of autoxidation was first leveraged using controlled indoor chamber data in the presence of Arizona Test Dust (ATD) particles without UV light, and then extended to photochemistry. With UV light, SO2 photooxidation was promoted by surface oxidants (OH radicals) that are generated via the photocatalysis of semiconducting metal oxides (electron–hole theory) of ATD particles. This photocatalytic rate constant was derived from the integration of the combinational product of the dust absorbance spectrum and wave-dependent actinic flux for the full range of wavelengths of the light source. The predicted concentrations of sulfate and nitrate using the AMAR model agreed well with outdoor chamber data that were produced under natural sunlight. For seven consecutive hours of photooxidation of SO2 in an outdoor chamber, dust chemistry at the low NOx level was attributed to 55 % of total sulfate (56 ppb SO2, 290 µg m−3 ATD, and NOx less than 5 ppb). At high NOx ( >  50 ppb of NOx with low hydrocarbons), sulfate formation was also greatly promoted by dust chemistry, but it was suppressed by the competition between NO2 and SO2, which both consume the dust-surface oxidants (OH radicals or ozone).

Preparation of nitrogen-doped anatase TiO2 nanoworm/nanotube hierarchical structures and its photocatalytic effect

2014 ◽  
Vol 29 ◽  
pp. 27-33 ◽  
Author(s):  
Xian Hou ◽  
Cheng-Wei Wang ◽  
Wei-Dong Zhu ◽  
Xiang-Qian Wang ◽  
Yan Li ◽  
...  
Keyword(s):  
Hierarchical Structures ◽  
Anatase Tio2 ◽  
Nitrogen Doped ◽  
Photocatalytic Effect

scholarly journals Preparation of Visible Light Photocatalytic Graphene Embedded Rutile Titanium(IV) Oxide Composite Nanowires and Enhanced NOx Removal

Catalysts ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 170 ◽  
Author(s):  
Jun-Cheol Lee ◽  
Anantha-Iyengar Gopalan ◽  
Gopalan Sai-Anand ◽  
Kwang-Pill Lee ◽  
Wha-Jung Kim
Keyword(s):  
Electron Microscopy ◽  
Visible Light ◽  
Diffuse Reflectance Spectroscopy ◽  
Anatase Tio2 ◽  
Nox Removal ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Heat Treated ◽  
New Strategy ◽  
New Type

The quest for developing highly efficient TiO2-based photocatalysts is continuing and, in particular, evolving a new strategy is an important aspect in this regard. In general, much effort has been devoted to the anatase TiO2 modifications, despite there being only a few recent studies on rutile TiO2 (rTiO2). To the best of our knowledge, studies on the preparation and characterization of the photocatalysts based on the intentional inclusion of graphene (G) into rTiO2 nanostructures have not been reported yet. Herein, we develop a new type of TiO2-based photocatalyst comprising of G included pure rTiO2 nanowire (abbreviated as rTiO2(G) NW) with enhanced visible light absorption capability. To prepare rTiO2(G) NW, the G incorporated titanate electrospun fibers were obtained by electrospinning and subsequently heat treated at various temperatures (500 to 800 °C). Electrospinning conditions were optimized for producing good quality rTiO2(G) NW. The rTiO2(G) NW and their corresponding samples were characterized by appropriate techniques such as X-ray diffraction (XRD), scanning electron microscopy, high-resolution transmission electron microscopy and UV-vis diffuse reflectance spectroscopy to ascertain their material characteristics. XRD results show that the lattice strain occurs upon inclusion of G. We present here the first observation of an apparent bandgap lowering because of the G inclusion into TiO2 NW. While anatase TiO2 NW exhibited poor visible light photocatalysis towards NOx removal, the rTiO2(G) NW photocatalyst witnessed a significantly enhanced (~67%) photocatalytic performance as compared to anatase TiO2(G) NW. We concluded that the inclusion of G into rTiO2 nanostructures enhances the visible light photoactivity. A plausible mechanism for photocatalysis is suggested.

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