Browsing by Author "Wu, Hung-Yu"

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Improved Performance of MIC Poly-Si TFTs Using Driven-in Nickel Induced Crystallization (DIC) with Cap SiO2 by F implantation
(2010)
Lai, Ming-Hui
;
Wu, YewChung Sermon
;
Tung, Teng-Fu
;
Wu, Hung-Yu
;
材料科學與工程學系
A cap oxide layer was employed to substantially decrease nickel residues and passivate the trap states of the devices. F+ implantation was used to drive Ni in alpha-Si layer to induce crystallization (DIC) process with cap oxide to reduce Ni concentration and minimize the trap-state density. As a result, DIC-TFT with cap oxide exhibit higher field-effect mobility, lower subthreshold slope, lower threshold voltage, higher on/off current ratio, and lower trap-state density (N-t) compared with conventional MIC TFTs.
Metal-doped Photocatalysts to Reduce Carbon Dioxide in Ethanolamine Solution for Methane Production
(2012)
Wu, Hung-Yu
;
Bai, Hsunling
;
Wu, Jeffrey C. S.
;
環境工程研究所
;
Institute of Environmental Engineering
Photocatalytic reduction of carbon dioxide (CO2) to form valuable energy source of methane (CH4) in the ethanolamine (MEA) solution is investigated in this study. The TiO2 photocatalysts were prepared by doping with nano-sized metals (Fe, Zn, Mn, Ce) via the co-precipitation method. The photocatalytic reduction process was performed in the MEA solution because the MEA absorption is one of the most popular methods for CO2 greenhouse gas capture from flue gas streams. And it is intended to integrate the CO2 capture and utilization into one process. The tests were performed with the UV light source of 9W and 365 nm. The light intensity of 6.3 mW/cm(2) was measured at the center point between the UV light source and the outer glass of the reactor. The 5 hours test results showed the methane yield followed the order of Ce-TiO2 > Mn-TiO2> Zn-TiO2 > Fe-TiO2. Tests were also evaluated with a solar light concentrator, and it has been proved that it is possible to produce CH4 under solar light without the addition of any external energy source.
Photocatalytic reduction of CO2 using molybdenum-doped titanate nanotubes in a MEA solution
(2015-01-01)
Wu, Hung-Yu
;
Nhat Huy Nguyen
;
Bai, Hsunling
;
Chang, Sue-min
;
Wu, Jeffrey C. S.
In this study, the photocatalytic reduction of CO2 in a monoethanolamine solution to form valuable energy sources was investigated using Mo-doped TNTs photocatalysts for the first time. The results revealed that the structure of Mo-doped TNTs changed with the increase of calcination temperature. For Mo-doped TNTs calcined at 500 degrees C, the partial corruption of titanate nanotubes into anatase particles caused the reduction of Mo species from Mo6+ to Mo5+ and produced oxygen vacancies, which resulted in the highest CO2 reduction ability. The yield rates of CH4, CO and total combustible organic compounds were 0.52, 10.41 and 13.53 mu mol g(cat)(-1), respectively, under UVA (8 W, 63 mu W cm(-2)) irradiation. The photoreduction quantum efficiencies of CH4 and CO were achieved at 0.036% and 0.180%, respectively. It was found that the molybdenum structure and oxygen vacancies could be the key factors controlling the photocatalytic reduction efficiency of CO2. A possible structure transformation of Mo-doped TNTs at different calcination temperatures was inferred and the reaction mechanism for photocatalytic CO2 reduction with oxygen vacancy sites of Mo-doped TNTs was proposed.
Photocatalytic Reduction of CO2 Using Ti-MCM-41 Photocatalysts in Monoethanolamine Solution for Methane Production
(2014-07-16)
Wu, Hung-Yu
;
Bai, Hsunling
;
Wu, Jeffrey C. S.
;
環境工程研究所
;
Institute of Environmental Engineering
Photocatalytic reduction of carbon dioxide (CO2) to form a valuable energy source of methane (CH4) in monoethanolamine (MEA) solution is first investigated by mesoporous photocatalysts of Ti-MCM-41 in this study. The MEA solution was chosen as the absorbent and reductant because amine absorption is one of the most popular methods for CO2 capture from flue gas streams. Also, it is intended to integrate the CO2 capture and utilization into one process. The photocatalytic results of methane yields indicated that MEA served as a better reductant than water and NaOH which have been commonly used for CO2 reduction. For the best photocatalyst of Ti-MCM-41(50) manufactured at a Si/Ti molar ratio of 50, its methane yield (62.42 mu mol/g of cat.) was much higher than that of commercial P25 photocatalyst after 8 h of UV illumination. A photoreduction quantum efficiency (PQE) of 9.18% was achieved.
Photocatalytic Reduction of CO2 Using Ti-MCM-41 Photocatalysts in Monoethanolamine Solution for Methane Production
(2014-07-16)
Wu, Hung-Yu
;
Bai, Hsunling
;
Wu, Jeffrey C. S.
;
環境工程研究所
;
Institute of Environmental Engineering
Photocatalytic reduction of carbon dioxide (CO2) to form a valuable energy source of methane (CH4) in monoethanolamine (MEA) solution is first investigated by mesoporous photocatalysts of Ti-MCM-41 in this study. The MEA solution was chosen as the absorbent and reductant because amine absorption is one of the most popular methods for CO2 capture from flue gas streams. Also, it is intended to integrate the CO2 capture and utilization into one process. The photocatalytic results of methane yields indicated that MEA served as a better reductant than water and NaOH which have been commonly used for CO2 reduction. For the best photocatalyst of Ti-MCM-41(50) manufactured at a Si/Ti molar ratio of 50, its methane yield (62.42 mu mol/g of cat.) was much higher than that of commercial P25 photocatalyst after 8 h of UV illumination. A photoreduction quantum efficiency (PQE) of 9.18% was achieved.
Photocatalytic reduction of NO2 and CO2 using molybdenum-doped titania nanotubes
(2015-06-01)
Nhat Huy Nguyen
;
Wu, Hung-Yu
;
Bai, Hsunling
;
環境工程研究所
;
Institute of Environmental Engineering
The preparation of molybdenum-doped hydrothermal titania nanotubes (Mo-doped TNTs) and its special photocatalytic reduction activity on NO2 and CO2 gases are reported for the first time. The TNTs photocatalysts were synthesized by hydrothermal method while Mo metal species was doped at different process steps corresponding to three fabrication methods: hydrothermal, precipitation, and impregnation. The materials were then characterized by BET, SEM, TEM, ICP, TPD, XPS, UV-Vis adsorption, and XRD analyses. The results indicated that Mo doping was successful by precipitation and impregnation, but not by the conventional hydrothermal method. It also revealed that the doping of Mo did not considerably affect the morphology, microstructure, and crystalline structure. However, it moderately changed the electronic band structure as well as surface acidity and basicity of the TNTs materials. The NO2 photocatalytic reaction results showed that the doping of Mo sharply declined the oxidation ability of TNTs while surprisingly enhanced its reduction ability. The CO2 reduction results further confirmed this special reduction ability of Mo-doped TNTs, which produced much higher yields of methane and carbon monoxide. The photocatalytic reaction results of both NO2 and CO2 showed that Mo-doped TNTs prepared by the precipitation method provided the highest reduction ability, which may be due to its chemical oxidation states of Mo4+ and Mo5+. (C) 2015 Elsevier B.V. All rights reserved.