Papers

ICMCTF2006 Session D4: Frontier Devices for Bio, Energy- and Optoelectronic-Applications Based on Carbon and Nitride Materials

Friday, May 5, 2006 9:10 AM in Room Sunrise

Friday Morning

Start	Invited?	Item
9:10 AM		D4-3 Carbon-Nanotube Based Electrochemical Sensors J. Wang (Arizona State University) The unique chemical and physical properties of carbon-nanotubes (CNT) have paved the way to new and improved sensing devices, in general, and electrochemical biosensors, in particular. CNT-based electrochemical transducers offer substantial improvements in the performance of amperometric enzyme electrodes, immunosensors and nucleic-acid sensing devices. The greatly enhanced electrochemical reactivity of hydrogen peroxide and NADH at CNT-modified electrodes makes these nanomaterials extremely attractive for numerous oxidase- and dehydrogenase-based amperometric biosensors. This presentation will cover recent advances in the use of CNT for electrochemical biosensors, including novel designs of CNT-based electrical transducers and hybrid layers, and devices ranging from enzyme electrodes to DNA sensors.
9:50 AM		D4-5 Biofunctionalization of Diamond for Cell Growth and Bio-Sensing K.P. Loh (National University of Singapore) Boron-doped diamond can be used as a signal transducer for biomolecules because of its wide electrochemical potentianl window and chemical stability. In this work, we discussed the chemistry of biofunctionalization used for making biosensors and surface electronics devices on diamond. Cycloaddition chemistry, electrochemical polymerisation, as well as UV-excited photochemistry of organic molecules on diamond will be discussed based on the results from core level spectroscopy and HREELS experiments carried out in our laboratory. Results of the electrochemical impedance sensing of linear, circular DNA and G-quadruplex on diamond electrodes will be presented. We also showed results on the growth and activation of cells on bio-functionalised diamond.
10:30 AM		D4-7 Luminescence and Impedance Spectroscopic Studies of GaN Nanowires with Immobilized DNA C-P. Chen, A. Ganguly, L.-C. Chen (National Taiwan University, Taiwan); K.-H. Chen (IAMS, Academia Sinica, Taiwan) Optical detection techniques are usually employed in commercially available state-of-the-art DNA micro-arrays, wherein the target molecules are labeled with fluorescence or chemoluminescence marker molecules. While electronic solutions offer promising opportunities in system miniaturization, improved ease-of-use and reduced cost for biosensors, development in this type of biosensors is still in its infant stage as compared to their optical counterparts. In this paper surface functionalization of the GaN nanowires that allows immobilization of the DNA and studies of their sensor response by both optical and electrochemical impedance techniques will be reported. GaN nanowires were prepared by catalytic chemical vapor deposition. These nanostructures are single crystals of nearly defect-free quality, as manifested by extremely sharp band edge photoluminescence (PL) emissions and weaker PL quenching in comparison to their thin-film counterparts. The one dimensional form of this nanomaterial not only leads to higher emission efficiency but also enables a path for electrical detection with sensitivity potentially higher than that achievable by its thin film counterpart. Moreover, it is observed that GaN nanowires changed from hydrophobic to hydrophilic upon surface oxidation, which in turn is an effective intermediate step to immobilize DNA. Both PL and impedance spectroscopic measurements revealed significant signal changes from the unmodified to modified nanowires with single-strand or double-strand DNA. Thus the applicability of the GaN nanowires as dual-function biosensors is demonstrated.
10:50 AM		D4-8 Functionalization of Carbon Nanotubes for the Electrode of Fuel Cells and Supercapacitors K.-H. Chen (IAMS, Academia Sinica, Taiwan); C.-H. Wang, W.-C. Fang (National Tsing Hua University, Taiwan); C-.L. Sun (IAMS, Academia Sinica, Taiwan); Y.-T. Tsai, H.-Y. Du (Chinese Culture University, Taiwan); C-P. Chen (National Taiwan University, Taiwan); J.-H. Huang, H.-C. Shih (National Tsing Hua University, Taiwan); O. Chyan (University of North Texas); L.-C. Chen (National Taiwan University, Taiwan) Direct growth of bamboo-like carbon nanotubes (CNTs) on carbon cloth and silicon has been performed to investigate its benefit on the electrodes for fuel cells and supercapacitor. With the good electric conductivity of the CNTs, much improvement in their performance is expected due to the enhancement of surface area. Much reduce of Pt-Ru catalyst has been demonstrated when CNT is grown directly on a carbon cloth for fuel cell anode. Meanwhile, significant enhancement in supercapacitor performance has been achieved via the CNT-RuO₂ nanocomposite materials prepared by direct ruthenium sputtering on arrayed multi-walled carbon nanotubes supported by a Si wafer. Detailed characterization of the carbon cloth-CNT-catalyst and the CNT-RuO₂ surface and interface has been carried out to elucidate the systems. Nitrogen incorporation into the graphitic structure has been identified to be the key for the nucleation of Pt and RuO₂ in fuel cells and supercapacitors, respectively. Quantum mechanical calculation based on density function theory has been applied to confirm the role of nitrogen.
11:30 AM		D4-10 Energy Related Applications of Carbon nanotubes Syntehsized Using Novel Alloy Hydride Catalysts S. Ramaprabhu (Altermative Energy Technology Laboratory, India) The talk presents the synthesis of different types of carbon nanotubes by the pyrolysis of suitable hydrocarbons over selective novel alloy hydride catalysts by the chemical vapour deposition (CVD) technique. The advantages of this novel approach to catalyst preparation using hydrogen decrepitation with reference to the increase in the catalytic reactivity and active sites for the formation of different types of CNTs are high lightened. A growth process of CNTs with alloy hydride catalysts by vapour-liquid-solid (VLS) mechanism is proposed. The results of the different characterization of the as-grown and purified CNTs are described. The dependence of the yield and the purity of the CNTs synthesized on the alloy hydride catalysts are discussed. The purified CNTs are used for different types of energy-related applications such as hydrogen storage, catalysts support for proton exchange membrane fuel cell (PEMFC) and supercapacitors. The various experimental techniques developed for these energy- related applications of CNTs are presented. The results obtained from the hydrogen adsorption studies carried out for the as-grown and purified MWNTs synthesized by pyrolysis of selective hydrocarbon using different alloy hydride catalysts using a high pressure Seiverts apparatus, have been discussed. The current-voltage characteristics of a PEMFC fabricated with MWNTs supported Pt electrocatalysts as cathode catalysts studied using a PEMFC test station comprising of a single stack fuel cell have been discussed. Purified MWNTs synthesized by the pyrolysis of acetylene using various alloy hydride catalysts have been used as supercapacitor electrode materials and the electrochemical performance have been discussed.