Browsing by Author "Cheng, Ta-Ming"

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(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.
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.
Glucose sensing by electrochemically grown copper nanobelt electrode
(2009-11-15)
Huang, Ting-Kai
;
Lin, Kuan-Wen
;
Tung, Sze-Ping
;
Cheng, Ta-Ming
;
Chang, I-Chun
A simple design of growing Cu nanobelt (NB) electrode for glucose sensing is presented. Cu NBs were grown directly on carbon electrodes by using electrochemical deposition. The average width, thickness and length of the NBs were about 50 nm, 20 nm and several tens of micrometers, respectively. Cyclic voltammetric (CV) experiments showed that a Cu NB electrode grown by a reduction charge of 0.5 C on a substrate of 0,018 cm(2) enhanced glucose oxidation ability. For glucose sensing, the electrode exhibited a high sensitivity of 79.8 mu A/mM and a measurable detection limit of 10 mu M in amperometric detection. (C) 2009 Elsevier B.V. All rights reserved.
Urchin-like Ag Nanowires as Non-enzymatic Hydrogen Peroxide Sensor
(2012-04-01)
Hsiao, Wei-Han
;
Chen, Hsin-Yu
;
Cheng, Ta-Ming
;
Huang, Ting-Kai
;
Chen, Yu-Liang
Urchin-like Ag nanowires were prepared by reacting AgNO3(aq) with Cu metal in the presence of cetyltrimethylammonium chloride and HNO3(aq) on a screen printed carbon electrode at room temperature. The diameters of the nanowires were about 100 nm, while the lengths were up to 10 mu m. Cyclic voltammetric experiments using the Ag nanowires as the working electrode showed electrocatalytic H2O2 reduction. The electrode exhibited a high sensitivity of 4705 mu A mM(-3) me cm(-2) from 50 mu M to 10.35 rnM and a measurable detection limit of 10 mu M in amperometric detection. This is the first report on Ag NWs for non-enzymatic H2O2 sensing.