Browsing by Author "Chiu, Hsin-Tien"

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(101)-exposed anatase TiO2 nanosheets
(2008-04-08)
Peng, Chih-Wei
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Ke, Tsung-Yin
;
Brohan, Luc
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Richard-Plouet, Mireille
;
Huang, Ju-Chun
(110)-Exposed Gold Nanocoral Electrode as Low Onset Potential Selective Glucose Sensor
(2010-10-01)
Cheng, Ta-Ming
;
Huang, Ting-Kai
;
Lin, Huang-Kai
;
Tung, Sze-Ping
;
Chen, Yu-Liang
A straightforward electrochemical deposition process was developed to grow gold nanostructures, including nanocoral, nanothorn, branched belt, and nanoparticle, on carbon electrodes by reducing HAuCl(4) under constant potentials in mixtures containing CTAC and/or NaNO(3). Among the nanostructures, the quasi-one-dimensional nanocoral electrode showed the highest surface area. Because of this, it provided excellent electrochemical performances in cyclic voltammetric (CV) studies for kinetic-controlled enzyme-free glucose oxidation reactions. In amperometric studies carried out at 0.200 V in PBS (pH 7.40, 0.100 M), the nanocoral electrode showed the highest anodic current response. It also offered the greatest sensitivity, 22.6 mu AmM(-1)cm(-2), an extended linear range, 5.00 x 10(-2) mM to 3.00 x 10(1) mM, and a low detection limit, 1.00 x 10(1) mu m among the electrodes investigated in this study. In addition, the glucose oxidation by the nanocoral electrode started at -0.280 V. more negative than the one of using a commercial Au electrode as the working electrode. This is attributed to the presence of exposed Au (110) surfaces on the electrode. The feature was applied to oxidize glucose selectively in the presence of ascorbic acid (AA) and uric acid (UA), common interferences found in physiological analytes. With an applied voltage at -0.100 V. the AA oxidation (started at -0.080 V) can be avoided while the glucose oxidation still provides a significant response.
(110)-Exposed Gold Nanocoral Electrode as Low Onset Potential Selective Glucose Sensor
(2010-10-01)
Cheng, Ta-Ming
;
Huang, Ting-Kai
;
Lin, Huang-Kai
;
Tung, Sze-Ping
;
Chen, Yu-Liang
A straightforward electrochemical deposition process was developed to grow gold nanostructures, including nanocoral, nanothorn, branched belt, and nanoparticle, on carbon electrodes by reducing HAuCl(4) under constant potentials in mixtures containing CTAC and/or NaNO(3). Among the nanostructures, the quasi-one-dimensional nanocoral electrode showed the highest surface area. Because of this, it provided excellent electrochemical performances in cyclic voltammetric (CV) studies for kinetic-controlled enzyme-free glucose oxidation reactions. In amperometric studies carried out at 0.200 V in PBS (pH 7.40, 0.100 M), the nanocoral electrode showed the highest anodic current response. It also offered the greatest sensitivity, 22.6 mu AmM(-1)cm(-2), an extended linear range, 5.00 x 10(-2) mM to 3.00 x 10(1) mM, and a low detection limit, 1.00 x 10(1) mu m among the electrodes investigated in this study. In addition, the glucose oxidation by the nanocoral electrode started at -0.280 V. more negative than the one of using a commercial Au electrode as the working electrode. This is attributed to the presence of exposed Au (110) surfaces on the electrode. The feature was applied to oxidize glucose selectively in the presence of ascorbic acid (AA) and uric acid (UA), common interferences found in physiological analytes. With an applied voltage at -0.100 V. the AA oxidation (started at -0.080 V) can be avoided while the glucose oxidation still provides a significant response.
{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.
Alkali metal ion assisted synthesis of faceted anatase TiO2
(2013)
Yang, Min-Han
;
Chen, Po-Chin
;
Tsai, Min-Chiao
;
Chen, Ting-Ting
;
Chang, I-Chun
This work reports on a simple hydrothermal method for tuning the shape and exposed face of TiO2 nanocrystal by using sodium titanate as a precursor in the presence of different alkali metal ion salts. The {101}-exposed anatase TiO2 was synthesized in lithium salt solution. The formation of anatase TiO2 with exposed high-index {301} facet, obtained in the presence of sodium ions, has never before been reported upon. When the reaction proceeded in potassium salt solution, the obtained anatase TiO2 with a high aspect ratio was elongated in the < 001 > direction. Anatase TiO2 with a high aspect ratio was obtained in hydrothermal process in the presence of low charge density high atomic number alkali metal ions, which were not easily absorbed by the {001} planes of anatase, so the growth along this direction was not restrained. The photodegradation of methylene blue, assisted by anatase TiO2 with various exposed faces reveals that the photoactivity of anatase {101} planes is larger than that of {301} planes.
Anatase and brookite TiO2 with various morphologies and their proposed building block
(2014)
Yang, Min-Han
;
Chen, Po-Chin
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Tsai, Min-Chiao
;
Chen, Ting-Ting
;
Chang, I-Chun
In this work, brookite TiO2 has been synthesized by a simple hydrothermal approach using sodium titanate as a precursor in the presence of a sodium fluoride aqueous solution. The ratio of brookite and anatase TiO2 can be tailored by the NaF concentration. In a concentrated NaF solution, high quality brookite TiO2 was acquired. Pure anatase nanoparticles were obtained in only deionized water. Moreover, the morphology and size of brookite TiO2 can be tailored by using various acid treated titanates which influence the stability of the building blocks and nucleation points of TiO2. Micro-sized flower-like brookite, submicro-sized urchin-like brookite and brookite nanorods with anatase nanoparticles were obtained. The micro-sized flower-like brookite remains the same shape and phase even at 800 degrees C, whereas obvious grains were formed on the matrix with brookite, rutile and anatase mixture phases at 900 degrees C. On the other hand, as the submicro-sized urchin-like brookite was heated, a rutile phase appeared at 750 degrees C and 100% grain-like rutile was obtained at 900 degrees C.
Arginine-Assisted Formation of Hierarchical TiO2 Microspheres for Lithium-Ion and Sodium-Ion Battery Applications
(2016-12)
Chang, Yi-Chun
;
Wang, Yu-Xuan
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Lee, Chi-Young
;
Chiu, Hsin-Tien
;
應用化學系
A facile route was established to synthesize hierarchically structured high specific surface area (122 m(2)g(-1)) TiO2 microspheres (diameter: 0.5-1 mu m). In a heated Teflon-coated stainless-steel autoclave, titanium tetrabutoxide Ti(OBu)(4), arginine, and absolute ethanol were reacted via the solvothermal reaction to generate the TiO2 precursor. The as-formed precursor solid was further processed at 673K under air to generate the TiO2 microspheres of nanosheets (thickness: 18 nm). The products were examined as potential anode materials for Li-ion and Na-ion batteries. After 100 cycles at 0.1 C (1C = 335 mAhg(-1)), the assembled batteries showed respectable specific capacity 241 mAhg(-1) and 145 mAhg(-1) for Li-ion and Na-ion batteries, respectively.
Artificial Synthesis of Platelet-Like Kassite and Its Transformation to CaTiO(3)
(2010-03-01)
Huang, Yi-Jen
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Tsai, Min-Chiao
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Chiu, Hsin-Tien
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Sheu, Hwo-Shuenn
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Lee, Chi-Young
Platelet-like kassite, a rare mineral CaTi(2)O(4)(OH)(2), wits synthesized by a wet chemical route using Ca(OH)(2) and TiO(2) as reagents in base Solution. The microstructure of the obtained kassite examined by synchrotron radiation and Rietveld refinement are hexagonal (P312) with a = b = 0.52451(2) and c = 0.47844(3) nm. This cell is slightly different from JCPDS No. 88-1722. At heating above 500 degrees C, the layered crystalline kassite rearranges to form disk-like CaTiO(3) and amorphous TiO(2) by removing H(2)O completely. Furthermore, transmission electron microscopy analysis reveals that the vertical axis of disk-like CaTiO(3) along the [0 (2) over bar1] direction converts from that of [001] orkassite.
Artificial Synthesis of Platelet-Like Kassite and Its Transformation to CaTiO3
(2010-03-01)
Huang, Yi-Jen
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Tsai, Min-Chiao
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Chiu, Hsin-Tien
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Sheu, Hwo-Shuenn
;
Lee, Chi-Young
Platelet-like kassite, a rare mineral CaTi2O4(OH)(2), wits synthesized by a wet chemical route using Ca(OH)(2) and TiO2 as reagents in base Solution. The microstructure of the obtained kassite examined by synchrotron radiation and Rietveld refinement are hexagonal (P312) with a = b = 0.52451(2) and c = 0.47844(3) nm. This cell is slightly different from JCPDS No. 88-1722. At heating above 500 degrees C, the layered crystalline kassite rearranges to form disk-like CaTiO3 and amorphous TiO2 by removing H2O completely. Furthermore, transmission electron microscopy analysis reveals that the vertical axis of disk-like CaTiO3 along the [0 (2) over bar1] direction converts from that of [001] orkassite.
Bio-ingredient assisted formation of porous TiO2 for Li-ion battery electrodes
(2015-01-01)
Chang, Yi-Chun
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Peng, Chih-Wei
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Chen, Po-Chin
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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.
Carbon nanobeads as an anode material on high rate capability lithium ion batteries
(2009-11-30)
Chang, Jian-Chia
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Tzeng, Yu-Fen
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Chen, Jin-Ming
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Chiu, Hsin-Tien
;
Lee, Chi-Young
Carbon nanobeads (CNBs) were prepared by reacting cyclohexachlorobenzene with dispersed sodium metal at 200 degrees C for 4 h. The CNBs prepared in this manner formed uniform nanobeads, with sizes ranging from 100 to 300 nm. Heating resulted in a reduction in the size of the CNBs, and improvements in their degree of crystallinity. The nanosized carbon materials considerably increased the surface area of the powder, reducing the distance of the intercalation/deintercalation pathway, substantially improving the charge capacity of the lithium ion battery at a high charging rate. The charge capacity of CNBs was found to be 238 mAh g(-1), while that of commercial MCMB reached only 36 mAh g(-1), when the charging rate was 1C (372 mAh g(-1)). As the charging rate was further increased to 2C (744 mAh g(-1)) and 3C (1116 mAh g(-1)), the charge capacities of CNBs dropped to 173 and 111 mAh g(-1), respectively. The cyclic performance of the CNBs was measured and found to be significantly improved in comparison to other carbonaceous materials, for up to 100 cycles. Although cyclic performance did result in a gradual reduction in capacity, the CNBs still greatly exceeded the capacity of MCMB. These results clearly demonstrate the potential role of CNBs as anodes for high capacity Li ion batteries for use in the automobile industry. (C) 2009 Elsevier Ltd. All rights reserved.
Chemical Vapor Deposition of Carbon Nanocoils Three-Dimensionally in Carbon Fiber Cloth for All-Carbon Supercapacitors
(2019-01-01)
Hu, Shin
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Lee, Chi-Young
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Chiu, Hsin-Tien
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應用化學系
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Department of Applied Chemistry
An Au/K bicatalyst-assisted chemical vapor deposition process using C2H2(g) to grow high-density carbon nanocoils (CNCs) uniformly on the fibers in carbon fiber cloth substrates three-dimensionally was developed. An as-deposited substrate (2.5 x 1.0 cm(2)) showed a high electrochemical active surface area (16.53 cm(2)), suggesting its potential usefulness as the electrode in electrochemical devices. The unique one-dimensional (1D) helical structure of the CNCs shortened the diffusion pathways of the ions in the electrolyte and generated efficient electron conduction routes so that the observed serial resistance R-s was low (3.7 Omega). By employing two-electrode systems, a liquid-state supercapacitor (SC) in H2SO4(aq) (1.0 M) and a solid-state SC with a polypropylene (PP) separator immersed in H2SO4(aq) (1.0 M)/polyvinylalcohol were assembled and investigated by using CNC-based electrodes. Both devices exhibited approximate rectangular shape profiles in the cyclic voltammetry measurements at various scan rates. The observations indicated their electric double-layer capacitive behaviors. From their galvanostatic charge/discharge curves, the specific capacitances of the liquid SC and the solid SC were measured to be approximately 137 and 163 F/g, respectively. In addition, the solid-state CNC-based SC possessed excellent energy density (15.3 W h/kg) and power density (510 W/kg). The light weight solid SC (0.1965 g, 2.5 x 1.0 cm(2)) was bendable up to 150 degrees with most of the properties retained.
Chemical Vapor Deposition of TiSi Nanowires on C54 TiSi(2) Thin Film: An Amorphous Titanium Silicide Interlayer Assisted Nanowire Growth
(2009-11-24)
Lin, Huang-Kai
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Cheng, Hsin-An
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Lee, Chi-Young
;
Chiu, Hsin-Tien
;
應用化學系
A C54-TiSi(2) film was grown on a Si substrate at 1073 K by low pressure chemical vapor deposition (LPCVD) employing titanium subchlorides TiCl(x)((g)), generated by reacting between TiCl(4(g)) and Ti((s)) at 1173 K, as the Ti source. Growth of titanium silicide (TiSi) nanowires (NWs; diameter 30-80 rim, length several micrometers) on a C54-TiSi(2) film was observed. Growth direction of the NWs was determined to be along the [010] axis. An amorphous titanium silicide interlayer was observed between the NWs and the C54-TiSi(2) film. This interlayer, probably existing as a quasi-liquid thin film during the growth, appears to be the key factor to assist the NW development. Field emission properties, turn-on field E(o) and field enhancement factor beta, of the vertically grown TiSi NWs were determined to be 5.25 V mu m(-1) and 876, respectively.
Chemical Vapor Deposition of TiSi Nanowires on C54 TiSi2 Thin Film: An Amorphous Titanium Silicide Interlayer Assisted Nanowire Growth
(2009-11-24)
Lin, Huang-Kai
;
Cheng, Hsin-An
;
Lee, Chi-Young
;
Chiu, Hsin-Tien
;
應用化學系
A C54-TiSi2 film was grown on a Si substrate at 1073 K by low pressure chemical vapor deposition (LPCVD) employing titanium subchlorides TiClx((g)), generated by reacting between TiCl4(g) and Ti-(s) at 1173 K, as the Ti source. Growth of titanium silicide (TiSi) nanowires (NWs; diameter 30-80 rim, length several micrometers) on a C54-TiSi2 film was observed. Growth direction of the NWs was determined to be along the [010] axis. An amorphous titanium silicide interlayer was observed between the NWs and the C54-TiSi2 film. This interlayer, probably existing as a quasi-liquid thin film during the growth, appears to be the key factor to assist the NW development. Field emission properties, turn-on field E-o and field enhancement factor beta, of the vertically grown TiSi NWs were determined to be 5.25 V mu m(-1) and 876, respectively.
Chimie Douce Route to Sodium Hydroxo Titanate Nanowires with Modulated Structure and Conversion to Highly Photoactive Titanium Dioxides
(2008-12-09)
Peng, Chih-Wei
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Richard-Plouet, Mireille
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Ke, Tsung-Yin
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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.
Considerable humidity response of a well-aligned SOMS micro-wire flexible sensor by moisture-induced releasing of trapped electrons
(2017-09-07)
Chan, Kuei-Lin
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Yang, Min-Han
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Chiu, Hsin-Tien
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Lee, Chi-Young
;
應用化學系
Sandia Octahedral Molecular Sieves micro-wires (SOMS MWs) that exhibit ultra-high response to moisture and a short response time can be produced easily in an environmentally friendly mass production process. They are excellent candidate materials for use in humidity sensors. SOMS MWs were synthesized using niobium pentoxide as a precursor in concentrated sodium hydroxide solution. To fabricate humidity-sensing devices, electrophoresis was utilized to align the SOMS MWs on a polyethylene terephthalate (PET) substrate. The degree of alignment of SOMS MWs can be tuned by controlling the electric field during electrophoresis. Both well-aligned SOMS MWs (S-1.00) and randomly distributed SOMS MWs (S-0.00) exhibit maximum sensitivities to humidity (RRH/RDRY) of almost 10(4) and 10(7) respectively, and both exhibit short response times (34 and 38 s) and recovery times (7 and 10 s); these MWs outperform metal oxide ceramic-based materials in sensing humidity. Furthermore, the humidity response of S-1.00 exceeds that of S-0.00 by three orders of magnitude, and this result cannot be explained with reference to the Grotthuss mechanism. Therefore, the moisture-induced carriers from trapped electrons contribute significantly to the humidity response of SOMS MWs. In addition, with outstanding humidity sensing-performance under extreme bending conditions and superior durability after being bent hundreds of times, the well-aligned SOMS MW sensor is a favorable candidate for emerging multifunctional electronic-skin.
Conversion oil Potassium Titanate Nanowires into Titanium Oxynitride Nanotubes
(2011-10-01)
Wei, Yen-Ju
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Peng, Chih-Wei
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Cheng, Ta-Ming
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Lin, Huang-Kai
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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.
Deposition of mesoporous silicon carbide thin films from (Me3Si)(4)Sn: Tin nanoparticles as in situ generated templates
(2007-10-30)
Wang, Chia-Hsin
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Shen, Wen-Yih
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Sheng, Pei-Sun
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Lee, Chi-Young
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Chiu, Hsin-Tien
With use of Sn(SiMe3)(4) as the precursor, amorphous SiC1+x thin films with Sri nanoparticles embedded were grown on Si substrates at 923 K by low-pressure chemical vapor deposition. After treatment under hydrogen plasma at 923 K, the Sri nanoparticles in the films were removed by an HF solution and by evaporation at 1423 K. Following the removal of Sri, high-temperature treatments at 1273-1423 K converted the amorphous thin films into mesoporous semiconducting beta-SiC thin films with pore sizes 10-100 nm.
Detecting HER2 on Cancer Cells by TiO(2) Spheres Mile Scattering
(2009-09-15)
Tsai, Min-Chiao
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Tsai, Tsung-Lin
;
Shieh, Dar-Bin
;
Chiu, Hsin-Tien
;
Lee, Chi-Young
This work is the first to describe a bioimaging method that uses highly uniformly sized TiO(2) submicrometer and micrometer spheres based on Mie scattering. Transmembrane proteins (HER2) located on the surface of cancer cells were detected by bonded antibody-linked TiO(2) spheres using optic microscopy and UV-vis spectroscopy. A particular HER2 bond on cancer cells, which has a weaker binding affinity than the biotin/avidin interaction, can be identified between TiO(2) spheres that are linked to anti-HER2 antibodies and those that are linked to nonspecific mouse IgG antibodies by observing the cells under an optical microscope or by measuring absorbance from a UV-vis spectrum. The TiO(2) spheres used in this work was prepared by reacting TTIP with carboxylic acid, as described elsewhere and the uniformity of the TiO(2) sphere was further improved by adjusting the amount of water used. The water content was inversely related to particle size and the size distribution: as more water was used, smaller spheres with a narrower size distribution were obtained. The most uniform sphere obtained had a diameter of about 1 mu m with a size variation of 3%.
Detecting HER2 on Cancer Cells by TiO2 Spheres Mile Scattering
(2009-09-15)
Tsai, Min-Chiao
;
Tsai, Tsung-Lin
;
Shieh, Dar-Bin
;
Chiu, Hsin-Tien
;
Lee, Chi-Young
This work is the first to describe a bioimaging method that uses highly uniformly sized TiO2 submicrometer and micrometer spheres based on Mie scattering. Transmembrane proteins (HER2) located on the surface of cancer cells were detected by bonded antibody-linked TiO2 spheres using optic microscopy and UV-vis spectroscopy. A particular HER2 bond on cancer cells, which has a weaker binding affinity than the biotin/avidin interaction, can be identified between TiO2 spheres that are linked to anti-HER2 antibodies and those that are linked to nonspecific mouse IgG antibodies by observing the cells under an optical microscope or by measuring absorbance from a UV-vis spectrum. The TiO2 spheres used in this work was prepared by reacting TTIP with carboxylic acid, as described elsewhere and the uniformity of the TiO2 sphere was further improved by adjusting the amount of water used. The water content was inversely related to particle size and the size distribution: as more water was used, smaller spheres with a narrower size distribution were obtained. The most uniform sphere obtained had a diameter of about 1 mu m with a size variation of 3%.