Browsing by Author "Peng, Chih-Wei"

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(101)-exposed anatase TiO2 nanosheets
(2008-04-08)
Peng, Chih-Wei
;
Ke, Tsung-Yin
;
Brohan, Luc
;
Richard-Plouet, Mireille
;
Huang, Ju-Chun
{110}-exposed rutile titanium dioxide nanorods in photocatalytic performance
(2009)
Ke, Tsung-Ying
;
Peng, Chih-Wei
;
Lee, Chi-Young
;
Chiu, Hsin-Tien
;
Sheu, Hwo-Shuenn
Single crystalline rutile TiO(2) nanorods were prepared by reacting sodium titanate with hydrochloric acid. The proposed formation mechanism involves a growth pathway. The growth proceeds along [001], and the circumferential faces are {110}, which are identified as the photoactive faces of rutile titanium dioxide. Both the heterogeneous ( photocatalyst only) and the combined heterogeneous/homogeneous (photocatalyst and H(2)O(2)) photocatalytic performances support its activity. The mechanism of formation and photocatalytic property are extensively studied.
Bio-ingredient assisted formation of porous TiO2 for Li-ion battery electrodes
(2015-01-01)
Chang, Yi-Chun
;
Peng, Chih-Wei
;
Chen, Po-Chin
;
Lee, Chi-Young
;
Chiu, Hsin-Tien
Macroporous TiO2 was synthesized by using low-cost bio-ingredients as the pore forming templates. TiCl4 in C2H5OH(l) containing NH4OH(aq.) was polymerized in the presence of instant yeast and glucose. The organic-inorganic hybrid precursor was further processed to generate macroporous anatase TiO2 (pore size: 2.5-3 mu m) with mesopores (4-51 nm). The porous TiO2 was coated with a thin layer of carbon by chemical vapour deposition to generate the hierarchical C/TiO2 nanocomposite material. The porous products were investigated as anode materials for Li-ion batteries. The capacities of the hierarchical C/TiO2 electrode material remained 180 mA h g(-1) and 142 mA h g(-1) under high charge/discharge rates of 5 C and 10 C, respectively. It demonstrated good cycling stability of 318 mA h g(-1) at 0.1 C at various discharge-charge rates. The excellent performance is attributed to the high specific surface areas and open spaces of the C/TiO2 allowing effortless intercalation/deintercalation of Li ions.
Chimie Douce Route to Sodium Hydroxo Titanate Nanowires with Modulated Structure and Conversion to Highly Photoactive Titanium Dioxides
(2008-12-09)
Peng, Chih-Wei
;
Richard-Plouet, Mireille
;
Ke, Tsung-Yin
;
Lee, Chi-Young
;
Chiu, Hsin-Tien
Sodium hydroxo titanate nanowires with NaTi(2)O(4)(OH) formulation are fabricated by chimie-douce from TiO(2) powders in a hot concentrated base solution. In the present work, we investigate, in detail, the structure and morphology of the titanate, acid-exchanged materials, and phases formed during dehydration of these compounds; we then discuss the relationship between the initial titanate structure and TiO(2) formation. XRD, ED, HRTEM, EDS, density measurements, and TG/MS results suggest that the titanate and acid-exchanged structures were closely related to the pseudolepidocrocite arrangement ("Cs(2)Ti(6)O(12)" type). The average structure of NaTi(2)O(4)(OH) nanowires consists of noncorrugated Ti(2)O(3)(OH) and NaO layers stacked along the [0 10] direction and an energy minimization was further conducted by theoretical methods. From TEM study, we demonstrated that NaTi(2)O(4)(OH) exhibits a modulated structure (q wave vector equals to 1/7 [001]*), which originates from the misfit between the NaO and Ti(2)O(3)(OH) sublattices. NaTi(2)O(4)(OH) structure has a monoclinic distortion (I2/m space group) with refined unit cell a = 0.37000(6) nm, b = 1.7816(4) nm, c = 2.2077(3) nm, beta = 92.70(1)degrees. Proton exchange followed by heat treatment convert the sodium hydroxo titanate into highly photoactive TiO(2) nanowires. The activity is attributed to the presence of preferentially exposed (001) surface plane which is explained by the topotactic phase transformation of TiO(2)(B) into anatase.
Conversion oil Potassium Titanate Nanowires into Titanium Oxynitride Nanotubes
(2011-10-01)
Wei, Yen-Ju
;
Peng, Chih-Wei
;
Cheng, Ta-Ming
;
Lin, Huang-Kai
;
Chen, Yu-Liang
Tunnel-structured potassium titanate with a K(3)Ti(8)O(17) phase was synthesized by direct oxidation of titanium powder mixed with KF(aq) in water vapor at 923 K. The reaction conditions were adjusted so that uniform single crystalline potassium titanate nanowires with [010] growth direction (length: 5-30 mu m, diameter: 80-100 nm) were obtained. Nitridation of the nanowires by NH(3)(g) at 973-1073 K converted the titartate nanowires into rock-salt structured cubic phase single crystalline titanium oxynitride TiN(x)O(y) nanotubes (x = 0.88, y = 0.12, length = 1-10 mu m, diameter = 150-250 nm, wall thickness = 30 - 50 nm) and nanorods (x = 0.5, y = 0.5, length 1-5 mu m, diameter = 100-200 nm) with rough surfaces and [200] growth direction. The overall conversion of the titanate nanowires into the nanotubes and the nanorods can be rationalized by Ostwald ripening mechanism. We fabricated an electrode by adhering TiN(x)O(y) nanotubes (0.2 mg) on a screen-printed carbon electrode (geometric area: 0.2 cm(2)). Electrochemical impedance spectroscopy demonstrated its charge transfer resistance to be 20 Omega. The electrochemical surface area of the nanotubes on the electrode was characterized by cyclic voltammetry to be 0.32 cm(2). This property suggests that the TiN(x)O(y) nanostructures can be employed as potential electrode materials for electrochemical applications.
Growth of Pagoda-Topped Tetragonal Copper Nanopillar Arrays
(2009-07-01)
Chang, I-Chun
;
Huang, Ting-Kai
;
Lin, Huang-Kai
;
Tzeng, Yu-Feng
;
Peng, Chih-Wei
Growth of arrays of pagoda-topped tetragonal Cu nanopillar (length 1 - 6 mu m; width 150 +/- 25 nm) with {100) side races on Au/glass is achieved by,a simple electrochemical reduction of CuCl(2)(aq) by Al(s) in aqueous dodecyltrimethylammonium chloride. Field-emission measurement shows that the Cu nanopillars can emit electrons (10 mu A cm(-2)) at a turn-on field or 12.4 V mu m(-1) with a calculated held enhancement factor of 713.
Interconversion of rutile TiO2 and layered ramsdellite-like titanates: New route to elongated mesoporous rutile nanoplates
(2008-10-01)
Peng, Chih-Wei
;
Richard-Plouet, Mireille
;
Tsai, Min-Chiao
;
Lee, Chi-Young
;
Chiu, Hsin-Tien
We report the first soft chemistry synthesis of a new "layered ramsdellite-like" titanate structure, NaTi2O4(OH) (lattice parameters: primitive monoclinic system, a = 4.09 nm, b = 0.29 nm, c = 0.94 nm, and beta = 80 degrees), with high-aspect-ratio, platelike morphology (diameter. 20-200 nm; thickness. 10-40 nm; length. 0.05-5 mu m) from TiO2 rutile. The newly prepared titanate can be transformed back to TiO2 rutile with uniquely shaped mesoporous elongated nanoplate morphology. The reaction proceeds via the disintegration of rutile in NaOH(aq) into NaTi2O4(OH). Ion exchange of Na+ in NaTi2O4(OH) into H+ forms another new layered ramsdellite-like titanate, HTi2O4(OH). A final topotatic condensation of the titanate layers in HTi2O4(OH) by heat treatment at relatively low 673 K produces the mesoporous TiO2 rutile product with highly exposed (110) surfaces.
Nanocarbon materials and process for producing the same
(2003-07-10)
Chang, Yu-Hsu
;
Chiu, Hsin-Tien
;
Lee, Chi-Young
;
Peng, Chih-Wei
;
Yen, Ming-Yu
In a process for producing nanocarbon materials, a metal reducing agent and a carbon source are subjected to a chemical reduction reaction under an atmosphere which will not interfere with the reaction and at a temperature preferably lower than 1000° C., such that a nanocarbon material having a graphite-like structure is formed therefrom. Optionally, an additive, e.g. a fullerene compound, or a porous substrate such as zeolite powder, may be used during the production of the nanocarbon material.
Phase segregation assisted morphology sculpting: Growth of graphite and silicon crystals via vapor-solid reactions
(2007-03-22)
Huang, Chih-Hao
;
Chang, Yu-Hsu
;
Lin, Huang-Kai
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Peng, Chih-Wei
;
Chung, Wen-Sheng
Crystalline graphite and Si showing fertile morphologies are prepared via vapor-solid reaction growth (VSRG). By reacting CaC2 with vapors of CxCly (CxCly: CCl4, C2Cl4, C4Cl6, and C5Cl6), porous, fibrous, and planar graphite were obtained at 973-1023, 1073-1123, and 1123-1223 K, respectively. Employing SiCl4 to react with MxSiy (MxSiy: Mg2Si and CaSi2) generated many Si structures. These include clustered-particle and porous, wirelike, corallike, and planar or platelike at 1023, 1073, 1123, and 1223 K, respectively. The reaction products, the network solids (graphite and Si) and the ionic solids MCl2, phase-segregated into self-templating molds and casts and develop cooperatively into various three-dimensional structures. Final morphology of the network solids depends not only on the reaction temperature but their molar volume ratio to the MCl2 salt products.
Preparation of titanium oxynitride nanotubes
(2011-03-27)
Wei, Yen-Ju
;
Peng, Chih-Wei
;
Lin, Huang-Kai
;
Lee, Chi-Young
;
Chiu, Hsin-Tien
Reactive template assisted growth of one-dimensional nanostructures of titanium dioxide
(2006-12-10)
Chung, Yao-An
;
Lee, Chi-Young
;
Peng, Chih-Wei
;
Chiu, Hsin-Tien
;
材料科學與工程學系
TiCl4 was employed to react with the reactive template Na@AAO, Na inside the channels of anodic aluminum oxide membranes, followed by O-2 oxidation at 623 K and annealed at 723 and 873 K to form one-dimensional nanostructures of TiO2. Free standing polycrystals of anatase TiO2 (diameter = 200-400 nm, length = 60 mu m) were obtained after the template was removed. (c) 2006 Elsevier B.V. All rights reserved.