Effect of a long-term exposure of anatase TiO2 powder doped with surface-located Sb3+ ions to UV radiation on its photocatalytic activity

2021 ◽  
Vol 31 (6) ◽  
pp. 896-898
Author(s):  
Mikhail V. Korolenko ◽  
Pavel B. Fabritchnyi ◽  
Mikhail I. Afanasov
Keyword(s):  
Photocatalytic Activity ◽  
Uv Radiation ◽  
Anatase Tio2 ◽  
Tio2 Powder

scholarly journals Photocatalytic Activity Enhancement of Low-pressure Cold-Sprayed TiO2 Coatings Induced by Long-term Water Vapor Exposure

2021 ◽  
Author(s):  
Seremak Wioletta ◽  
Baszczuk Agnieszka ◽  
Jasiorski Marek ◽  
Gibas Anna ◽  
Winnicki Marcin
Keyword(s):  
Titanium Dioxide ◽  
Photocatalytic Activity ◽  
Water Vapor ◽  
Sol Gel ◽  
Low Pressure ◽  
Oxygen Depletion ◽  
Amorphous Structure ◽  
Industrial Applications ◽  
Additional Parameter

AbstractThis work shows that the titanium dioxide coatings obtained by low-pressure cold gas spraying with the use of the sol–gel amorphous TiO2 powder are characterized by photocatalytic activity despite their partial amorphous content. Moreover, the research outcome suggests that the decomposition rate of organic pollutants is enhanced after long-term exposure to moisture. The condensation humidity test is not detrimental to the continuity and integrity of the coating, but the phase composition of coatings changes—with the exposure to water vapor, the portion of the amorphous phase crystallizes into brookite. The mechanism responsible for the conversion of amorphous TiO2 into brookite is attributed to the water-driven dissolution and reprecipitation of TiO6 octahedra. It has been shown that an additional parameter necessary for the stabilization of the brookite is the oxygen depletion of the amorphous structure of titanium dioxide. Considering the results presented in this paper and the advantages of a portable, low-pressure cold spray system for industrial applications, it is expected that TiO2 coatings produced from a sol–gel feedstock powder can be further developed and tested as efficient photocatalysts.

First-Principles Study on Electronic and Optical Properties in Pr-Doped Anatase TiO2

2014 ◽  
Vol 924 ◽  
pp. 260-268 ◽  
Author(s):  
Hao Chen ◽  
Lan Fang Yao ◽  
Song Lin Yang ◽  
Ya Qin Wang ◽  
Xing Liang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Photocatalytic Activity ◽  
First Principles ◽  
Energy Gap ◽  
Impurity Band ◽  
Anatase Tio2 ◽  
Electron Hole ◽  
Light Region ◽  
Overlap Population ◽  
Calculation Results

The crystal structures, band structures, density of states, charge density, overlap population and optical properties of pure anatase TiO2 and Pr-doped anatase TiO2 were studied by using the plane-wave pseudopotential method based on the first-principles. After Pr doping, the valence band and the conduction band moved down and became dense, energy gap became narrow and a impurity band which consists of Pr 4f states appeared. And the dipole moment got improved, which is good for the separate of the electron-hole pairs. These effectively overcome two huge shortcomings of TiO2. Besides, Pr-doped anatase TiO2 produced more carriers which have good transport properties and the absorption spectra of Pr-O bond appear in the region that the wavelength is longer. The calculation results of optical properties show that the absorption edge occured red shift, which means the photocatalytic activity of anatase TiO2 got remarkable improved during visible-light region. This conforms to the previous analysis. So the photocatalytic activity of anatase TiO2 got remarkable improved after Pr doping.

Influences on the Hydrophobicity of Concrete Surfaces Treated with Alkyl Trialkoxysilanes

2014 ◽  
Vol 20 (6) ◽  
pp. 405-412
Author(s):  
U. Antons ◽  
M. Raupach ◽  
O. Weichold
Keyword(s):  
Uv Radiation ◽  
Cement Hydration ◽  
Alkaline Media ◽  
Water Repellent ◽  
Portland Cement Concrete ◽  
Accelerated Carbonation ◽  
Surface Layers ◽  
Hydrophobic Layer ◽  
Furnace Slag

Abstract The paper focuses on how alkaline media, UV radiation, and carbonation as well as on-going cement hydration affects hydrophobic treatments of concrete and influences the properties of these water-repellent layers. Single-sided nuclear magnetic resonance measurements show that layers formed by impregnating samples with alkyl trialkoxysilanes are stable even under long-term exposure to alkaline solution and UV radiation, with the damage of the latter being limited to the topmost surface layers. Microstructural changes during accelerated carbonation of blast furnace slag cement based concrete have a major impact on the hydrophobic layer properties, while the carbonation of Portland cement concrete has no influence. On-going hydration additionally influences the hydrophobic layer properties.

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