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- 저자 : Lek Sikong (검색결과 2 건)
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Oxalic acid assisted synthesis of the photochromic tungsten trioxide nanostructure
Parnumart Choopool,Lek Sikong,Kalayanee Kooptarnond 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.12
The photochromic material, tungsten trioxide nanostructure has been successfully prepared by the simple precipitationmethod using nitric acid with the assistance of an oxalic acid. The effect of oxalic acid as the chelating agent on themorphologies, crystal structure, the optical properties and photochromic properties were investigated. The synthesizednanostructure characterized by X-ray diffractometer consisted of orthorhombic and hexagonal phase. The results fromscanning electron microscopy and transmission electron microscopy presented the flower-like shaped nanostructure formed bythe growth of many nanosheets. UV-vis spectrophotometer displayed the absorbance peak at lower than 550 nm. The band gapenergies of the products were decreased and the powder changed color from yellow to dark green after UV irradiation. Theproducts prepared with oxalic acid exhibited the highest photochromic effect due to the mixed phase of orthorhombic (81%)and hexagonal (19%) crystalline which having more defect concentration in its structure and the narrow band gap energy.
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Thida San Nwe,Lek Sikong,Rungrote Kokoo,Matthana Khangkhamano 한국물리학회 2020 Current Applied Physics Vol.20 No.2
The main drawbacks of anatase titanium dioxide (TiO2) nanoparticles for being used as a photocatalyst are due to the rapid charge recombination of the electron-hole pairs and the wide band gap energy, limiting its photocatalysis application. To enhance photocatalytic activity, structure modification was performed here. Heterogeneous nanostructure of Dy-doped TiO2 nanoparticles hybrid with Monoclinic TiO2 nanobelts (Dy/TNBs) was fabricated via hydrothermal method. Annealing temperature was varied to investigate its effect on phase composition and morphology of the as-prepared TiO2 catalyst. Phase composition and morphology were studied by XRD and SEM, respectively. The effect of amount of catalyst loaded on the degradation efficiency of methylene blue (MB) dye in aqueous solution under UV and fluorescence illumination was investigated. The results showed that pure monoclinic TiO2 nanobelts (TNBs) was achieved at 450 °C. Enhanced photocatalytic activity under both UV and fluorescence irradiation was found on Dy/TNB samples. The optimum Dy dosage providing the highest MB degradation rates under both irradiation sources was 0.1 mol%.
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