scholarly journals Reduction of dopant ions and enhancement of magnetic properties by UV irradiation in Ce-doped TiO2

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tai-Sing Wu ◽  
Leng-You Syu ◽  
Bi-Hsuan Lin ◽  
Shih-Chang Weng ◽  
Horng-Tay Jeng ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Uv Irradiation ◽  
Oxygen Vacancies ◽  
Magnetic Measurements ◽  
Uv Light ◽  
Theoretical Calculations ◽  
Light Irradiation ◽  
Optical Methods ◽  
Uv Light Irradiation ◽  
Spin Densities

AbstractWe report the experimental observation of and theoretical explanation for the reduction of dopant ions and enhancement of magnetic properties in Ce-doped TiO2 diluted magnetic semiconductors from UV-light irradiation. Substantial increase in Ce3+ concentration and creation of oxygen vacancy defects in the sample due to UV-light irradiation was observed by X-ray and optical methods. Magnetic measurements demonstrate a combination of paramagnetism and ferromagnetism up to room temperatures in all samples. The magnetization of both paramagnetic and ferromagnetic components was observed to be dramatically enhanced in the irradiated sample. First-principle theoretical calculations show that valence holes created by UV irradiation can substantially lower the formation energy of oxygen vacancies. While the electron spin densities for defect states near oxygen vacancies in pure TiO2 are in antiferromagnetic orientation, they are in ferromagnetic orientations in Ce-doped TiO2. Therefore, the ferromagnetically-oriented spin densities near oxygen vacancies created by UV irradiation are the most probable cause for the experimentally observed enhancement of magnetism in the irradiated Ce-doped TiO2.

Nanotribological Investigation of Magnetic Rigid Disks Lubricated with Perfluoropolyether Lubricant Under Varying Conditions

2008 ◽  
Vol 8 (5) ◽  
pp. 2719-2723 ◽  
Author(s):  
E. Liu ◽  
K. S. Tan ◽  
H. I. Tan
Keyword(s):  
Mechanical Properties ◽  
Uv Irradiation ◽  
Uv Light ◽  
Irradiation Time ◽  
Experimental Results ◽  
Light Irradiation ◽  
Loading Conditions ◽  
Uv Treatment ◽  
Uv Light Irradiation ◽  
Rigid Disks

This paper studies the nanotribological behavior of magnetic rigid disks dip-coated with ultra thin perfluoropolyether (PFPE) Z-Dol 4000 lubricant layers up to 4 nm thick prior to or after exposure to ultraviolet (UV) light irradiation. Lube bonding ratios (LBRs) of 43–91% were achieved by varying the UV irradiation time. The nanotribological and mechanical properties of the disks were measured with a nanotribometer under varying loading conditions. The effect of the LBR on the nanotribological behavior of the disks was also elucidated. We found that the lubricated disks after UV treatment performed better compared to the lubricated disks without UV treatment. The experimental results indicated that the LBR of about 50% could achieve the best contact-start–stop and flyability performances.

scholarly journals The influence of the UV irradiation intensity on photocatalytic activity of ZnAl layered double hydroxides and derived mixed oxides

2012 ◽  
Vol 18 (2) ◽  
pp. 295-303 ◽  
Author(s):  
Milica Hadnadjev-Kostic ◽  
Tatjana Vulic ◽  
Dmitar Zoric ◽  
Radmila Marinkovic-Neducin
Keyword(s):  
Photocatalytic Activity ◽  
Uv Irradiation ◽  
Layered Double Hydroxides ◽  
Mixed Oxide ◽  
Mixed Oxides ◽  
Uv Light ◽  
Light Irradiation ◽  
Irradiation Intensity ◽  
Uv Light Irradiation ◽  
Double Hydroxides

Layered double hydroxides (LDHs) have been studied to a great extent as environmental-friendly complex materials that can be used as photocatalysts or photocatalyst supports. ZnAl layered double hydroxides and their derived mixed oxides were chosen for the investigation of photocatalytic performances in correlation with the UV intensities measured in the South Pannonia region. Low supersaturation coprecipitation method was used for the ZnAl LDH synthesis. For the characterization of LDH and thermal treated samples powder X-ray diffraction (XRD), scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), nitrogen adsorption-desorption were used. The decomposition of azodye, methylene blue was chosen as photocatalytic test reaction. The study showed that the ZnAl mixed oxide obtained by thermal decomposition of ZnAl LDH has stable activity in the broader UV light irradiation range characterizing the selected region. Photocatalytic activity could be mainly attributed to the ZnO phase, detected both in LDH and thermally treated samples. The study showed that the ZnAl mixed oxide obtained by the calcination of ZnAl LDH has a stable activity within the measured UV light irradiation range; whereas the parent ZnAl LDH catalyst did not perform satisfactory when low UV irradiation intensity is implied.

Synthesis of MoS2/SrZrO3 heterostructures and their photocatalytic H2 evolution under UV irradiation

RSC Advances ◽  
2015 ◽  
Vol 5 (1) ◽  
pp. 734-739 ◽  
Author(s):  
Qingwen Tian ◽  
Li Zhang ◽  
Jiahui Liu ◽  
Naixu Li ◽  
Quanhong Ma ◽  
...  
Keyword(s):  
Uv Irradiation ◽  
Uv Light ◽  
Hydrothermal Process ◽  
Light Irradiation ◽  
H2 Evolution ◽  
Uv Light Irradiation ◽  
Photocatalytic H2 Evolution ◽  
Simple Hydrothermal Process

A novel heterojunction of a MoS2/SrZrO3 photocatalyst was successfully synthesized via a simple hydrothermal process and applied to photocatalytic H2 evolution under UV light irradiation.

scholarly journals Facile Preparation of Oxygen-Vacancy-Engineered MoOx Nanostructures for Photoreversible Switching Systems

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3192
Author(s):  
Hao Xu ◽  
Liangjing Zhang ◽  
Aiwu Wang ◽  
Juan Hou ◽  
Xuhong Guo
Keyword(s):  
Oxygen Vacancy ◽  
Oxygen Vacancies ◽  
Uv Light ◽  
Light Irradiation ◽  
Uv Light Irradiation ◽  
Highly Sensitive ◽  
Good Repeatability ◽  
Facile Preparation ◽  
Color Switching ◽  
Photochromic Materials

Photochromic materials have attracted increasing attention. Here, we report a novel photo-reversible color switching system based on oxygen-vacancy-engineered MoOx nanostructures with water/N-methyl-2-pyrrolidone (NMP) as solvents. In this work, the system rapidly changed from colorless to blue under UV irradiation (360–400 nm) and slowly recovered its colorless state under visible light irradiation. The obtained oxygen vacancy-engineered MoOx nanostructures exhibited good repeatability, chemical stability, and cycling stability. Upon UV light irradiation, H+ was intercalated into layered MoOx nanostructures and the Mo6+ concentration in the HxMoOx decreased, while the Mo5+ concentration increased and increased oxygen vacancies changed the color to blue. Then, it recovered its original color slowly without UV light irradiation. What is more, the system was highly sensitive to UV light even on cloudy days. Compared with other reported photochromic materials, the system in this study has the advantage of facile preparation and provides new insights for the development of photochromic materials without dyes.

scholarly journals TiO2-Powdered Activated Carbon (TiO2/PAC) for Removal and Photocatalytic Properties of 2-Methylisoborneol (2-MIB) in Water

Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1622
Author(s):  
Xiao-Pin Guo ◽  
Peng Zang ◽  
Yong-Mei Li ◽  
Dong-Su Bi
Keyword(s):  
Activated Carbon ◽  
Natural Organic Matter ◽  
Uv Light ◽  
Sol Gel ◽  
Light Irradiation ◽  
Nano Tio2 ◽  
Uv Light Irradiation ◽  
Adsorption Capacities ◽  
Taste And Odor ◽  
Composite Photocatalysts

2-methylisoborneol (2-MIB) is a common taste and odor compound caused by off-flavor secondary metabolites, which represents one of the greatest challenges for drinking water utilities worldwide. A TiO2-coated activated carbon (TiO2/PAC) has been synthesized using the sol-gel method. A new TiO2/PAC photocatalyst has been successfully employed in photodegradation of 2-MIB under UV light irradiation. In addition, the combined results of XRD, SEM-EDX, FTIR and UV-Vis suggested that the nano-TiO2 had been successfully loaded on the surface of PAC. Experimental results of 2-MIB removal indicated that the adsorption capacities of PAC for 2-MIB were higher than that of TiO2/PAC. However, in the natural organic matter (NOM) bearing water, the removal efficiency of 2-MIB by TiO2/PAC and PAC were 97.8% and 65.4%, respectively, under UV light irradiation. Moreover, it was shown that the presence of NOMs had a distinct effect on the removal of MIB by TiO2/PAC and PAC. In addition, a simplified equivalent background compound (SEBC) model could not only be used to describe the competitive adsorption of MIB and NOM, but also represent the photocatalytic process. In comparison to other related studies, there are a few novel composite photocatalysts that could efficiently and rapidly remove MIB by the combination of adsorption and photocatalysis.

Photocatalytic performance of Cu-doped titania thin films under UV light irradiation

2021 ◽  
Vol 553 ◽  
pp. 149535
Author(s):  
Elisa Moretti ◽  
Elti Cattaruzza ◽  
Cristina Flora ◽  
Aldo Talon ◽  
Eugenio Casini ◽  
...  
Keyword(s):  
Thin Films ◽  
Photocatalytic Performance ◽  
Uv Light ◽  
Light Irradiation ◽  
Uv Light Irradiation ◽  
Doped Titania
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