Browsing by Author "Wu, Ming-Cheng"

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alpha-MoO(3) nanocrystals of controlled size on a glass substrate
(2009-03-05)
Wu, Ming-Cheng
;
Lee, Chi-Shen
;
應用化學系
;
應用化學系分子科學碩博班
;
Department of Applied Chemistry
A procedure to grow alpha-MoO(3) nanocrystals of rod and belt forms under mild conditions involved deposition onto a glass substrate via vapor transport with a water-soluble precursor. Scanning electron and transmission electron microscopic studies, selected-area electron diffraction and powder X-ray analyses indicate that these alpha-MoO(3) nanocrystals exhibit rod or belt forms that grow along [0 0 1] and became vertically aligned on the glass substrate. Such deposition is effective to form thin films of controllable size and density of coverage on varying the precursor concentration and the duration of deposition. (C) 2008 Published by Elsevier Ltd.
alpha-MoO3 nanocrystals of controlled size on a glass substrate
(2009-03-05)
Wu, Ming-Cheng
;
Lee, Chi-Shen
;
應用化學系
;
應用化學系分子科學碩博班
;
Department of Applied Chemistry
A procedure to grow alpha-MoO3 nanocrystals of rod and belt forms under mild conditions involved deposition onto a glass substrate via vapor transport with a water-soluble precursor. Scanning electron and transmission electron microscopic studies, selected-area electron diffraction and powder X-ray analyses indicate that these alpha-MoO3 nanocrystals exhibit rod or belt forms that grow along [0 0 1] and became vertically aligned on the glass substrate. Such deposition is effective to form thin films of controllable size and density of coverage on varying the precursor concentration and the duration of deposition. (C) 2008 Published by Elsevier Ltd.
Controlled growth of beta-Na0.24V2O5 nanowire thin films
(2012-10-01)
Ke, Jhih-Syuan
;
Wu, Ming-Cheng
;
Weng, Sheng-Feng
;
Lee, Chi-Shen
;
應用化學系
A method to prepare well-aligned beta-Na0.24V2O5 nanowires (NWs) involves the deposition of a vanadium oxide complex onto a substrate via gaseous transport, followed by a reaction between the complex and a sodium cation (Na+) precursor coated on the substrate. Techniques to investigate the composition, crystallinity, and morphology of products as prepared include ICP-AES, X-ray powder diffraction (PXRD), SEM/transmission electron microscope (TEM), and XPS. PXRD patterns and images from a TEM confirm the single-crystalline nature of beta-Na0.24V2O5 NWs, which grow along direction [1 0 0]. Factors affecting the amount of deposited material and morphology were tested. On varying the reaction conditions, the length of the beta-Na0.24V2O5 wires is controlled in a range of 5-25 mu m. A mechanism of formation is proposed. According to measurements of field emission, the turn-on field is 7.8 V/mu m, and the maximum emission current density of 4.66 mA/cm(2) occurs at field 11 V/mu m. This method is applicable to grow other tertiary metal oxide nanostructures on glass substrate.
Controlled synthesis of VO2(R), VO2(B), and V2O3 vanadium-oxide nanowires
(2013-07-01)
Ke, Jhih-Syuan
;
Weng, Sheng-Feng
;
Wu, Ming-Cheng
;
Lee, Chi-Shen
;
應用化學系
Vanadium-oxide nanowires (NWs) V2O5, VO2(R), VO2(B), and V2O3 are deposited on a substrate to study their field-emission properties. V2O5 NWs are prepared by thermal evaporation via vapor transport of a vanadium-oxide complex under mild conditions. Films of VO2 and V2O3 wires are subsequently prepared by reducing V2O5 one-dimensional nanocrystals at 450 degrees C with hydrogen gas. The composition of the flowing H-2/Ar mixture and the duration of reduction are utilized to control the formation of VO2(R) or VO2(B) NWs. The crystallinity and morphology of products as prepared are characterized using several techniques, including powder X-ray diffraction, a scanning electron microscope, and a transmission electron microscope. The field-emission properties of the vanadium-oxide NWs as prepared exhibit a turn-on field of 4.56-7.65 V/mu m and an emission current density up to 3.68-8.36 mA/cm(2). These features indicate that vanadium-oxide NWs have potential FE emitter applications.
Field emission of vertically aligned V(2)O(5) nanowires on an ITO surface prepared with gaseous transport
(2009-08-01)
Wu, Ming-Cheng
;
Lee, Chi-Shen
;
應用化學系
;
Department of Applied Chemistry
Growing V(2)O(5) nanowires (NWs) on a conducting glass substrate combines gaseous transport and pyrolytic deposition of vanadium polyoxometalate anions, and yields vertically aligned vanadium-oxide nanowires. Scanning electron and transmission electron microscopy, selected-area electron diffraction, Raman spectra and powder X-ray analyses indicate that V(2)O(5) nanowires as synthesized were single-crystalline and grew anisotropically among direction [010]. NH(2)OH center dot HCl served not only as a reducing agent to produce vanadium polyoxometalate clusters but also as a source of NH(3) gas to facilitate the vapor pyrolysis and deposition. The optical properties of V(2)O(5) nanowires exhibit a character dependent on structure. Field emission (FE) measurements show a small turn-on field voltage similar to 8.3V/mu m, maximum Current density 1.8 mA/cm(2), and a linear Fowler-Nordheim behavior. (C) 2009 Elsevier Inc. All rights reserved.
Field emission of vertically aligned V2O5 nanowires on an ITO surface prepared with gaseous transport
(2009-08-01)
Wu, Ming-Cheng
;
Lee, Chi-Shen
;
應用化學系
;
Department of Applied Chemistry
Growing V2O5 nanowires (NWs) on a conducting glass substrate combines gaseous transport and pyrolytic deposition of vanadium polyoxometalate anions, and yields vertically aligned vanadium-oxide nanowires. Scanning electron and transmission electron microscopy, selected-area electron diffraction, Raman spectra and powder X-ray analyses indicate that V2O5 nanowires as synthesized were single-crystalline and grew anisotropically among direction [010]. NH2OH center dot HCl served not only as a reducing agent to produce vanadium polyoxometalate clusters but also as a source of NH3 gas to facilitate the vapor pyrolysis and deposition. The optical properties of V2O5 nanowires exhibit a character dependent on structure. Field emission (FE) measurements show a small turn-on field voltage similar to 8.3V/mu m, maximum Current density 1.8 mA/cm(2), and a linear Fowler-Nordheim behavior. (C) 2009 Elsevier Inc. All rights reserved.
Synthesis and thermal decomposition of Zn(tda)H2O [tda = S(CH2COO)(2)(2-)]
(2006-11-27)
Wu, Ming-Cheng
;
Lee, Chi-Shen
;
應用化學系
;
應用化學系分子科學碩博班
;
Department of Applied Chemistry
A novel two-dimensional coordination polymer Zn(tda)H2O [tda = S(CH2COO)(2)(2-)] was synthesized under hydrothermal conditions. The compound crystallized in monoclinic space group P2(1) with a = 16.4154(17) angstrom, b = 5.2133(6) angstrom, c = 16.4210(17) angstrom, beta = 114.165(2)degrees, V = 1282.1(2) angstrom(3), and Z = 8. The structure features two-dimensional, noncentrosymmetric networks with a pseudohexagonal network of Zn2+ coordinated by tda and water molecules. Zn(tda)H2O decomposed at T > 300 degrees C to form a ZnO sponge with a surface area similar to 40 m(2)/g, which makes it an attractive precursor for nanoporous ZnO.
Synthesis of In(OH)(3) and In(2)O(3) nanomaterials incorporating Au
(2009-02-01)
Chen, Shih-Yeh
;
Wu, Ming-Cheng
;
Lee, Chi-Shen
;
Lin, M. C.
;
應用化學系
In(OH)(3) and In(2)O(3) nanocrystals of rectangular shape and incorporating Au were synthesized with a hydrothermal process and thermal decomposition. Powder X-ray diffraction, electron microscopy (SEM, TEM), and energy-dispersive spectroscopy studies reveal that elemental Au nanoparticles are dispersed on the surface of In(OH)(3) rectangular nanocrystals and incorporated into In(2)O(3) nanoporous particles. UV-vis spectral measurements reveal a surface-enchanced plasma band near lambda 532 nm for both Au-incorporating nanomaterials. The BET surface areas of Au-incorporating In(OH)(3) and In(2)O(3) are 26.2 and 35.5 m(2)/g, respectively. The incorporation of elemental Au in In(OH)(3) and In(2)O(3) nanomaterials is attractive for sensor, catalyst and solar-cell applications.
Synthesis of In(OH)(3) and In2O3 nanomaterials incorporating Au
(2009-02-01)
Chen, Shih-Yeh
;
Wu, Ming-Cheng
;
Lee, Chi-Shen
;
Lin, M. C.
;
應用化學系
In(OH)(3) and In2O3 nanocrystals of rectangular shape and incorporating Au were synthesized with a hydrothermal process and thermal decomposition. Powder X-ray diffraction, electron microscopy (SEM, TEM), and energy-dispersive spectroscopy studies reveal that elemental Au nanoparticles are dispersed on the surface of In(OH)(3) rectangular nanocrystals and incorporated into In2O3 nanoporous particles. UV-vis spectral measurements reveal a surface-enchanced plasma band near lambda 532 nm for both Au-incorporating nanomaterials. The BET surface areas of Au-incorporating In(OH)(3) and In2O3 are 26.2 and 35.5 m(2)/g, respectively. The incorporation of elemental Au in In(OH)(3) and In2O3 nanomaterials is attractive for sensor, catalyst and solar-cell applications.