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Ulsan, South Korea

Sa Y.J.,Ulsan National Institute of Science and Technology | Sa Y.J.,Advanced Center for Energy | Park C.,Ulsan National Institute of Science and Technology | Jeong H.Y.,Low Dimensional Carbon Materials Center | And 7 more authors.
Angewandte Chemie - International Edition | Year: 2014

A facile, scalable route to new nanocomposites that are based on carbon nanotubes/heteroatom-doped carbon (CNT/HDC) core-sheath nanostructures is reported. These nanostructures were prepared by the adsorption of heteroatom-containing ionic liquids on the walls of CNTs, followed by carbonization. The design of the CNT/HDC composite allows for combining the electrical conductivity of the CNTs with the catalytic activity of the heteroatom-containing HDC sheath layers. The CNT/HDC nanostructures are highly active electrocatalysts for the oxygen reduction reaction and displayed one of the best performances among heteroatom-doped nanocarbon catalysts in terms of half-wave potential and kinetic current density. The four-electron selectivity and the exchange current density of the CNT/HDC nanostructures are comparable with those of a Pt/C catalyst, and the CNT/HDC composites were superior to Pt/C in terms of long-term durability and poison tolerance. Furthermore, an alkaline fuel cell that employs a CNT/HDC nanostructure as the cathode catalyst shows very high current and power densities, which sheds light on the practical applicability of these new nanocomposites. A facile, scalable route for the synthesis of new nanocomposites that are based on carbon nanotubes/heteroatom- doped carbon (CNT/HDC) core-sheath nanostructures has been developed. The CNT/HDC nanostructures exhibit excellent electrocatalytic activity, kinetics, and durability for the oxygen reduction reaction, and they also performed well as the cathode catalysts in alkaline fuel cells. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Kwon O.S.,Seoul National University | Park S.J.,Seoul National University | Hong J.-Y.,Seoul National University | Han A.-R.,Advanced Center for Energy | And 3 more authors.
ACS Nano | Year: 2012

Graphene-based field-effect transistors (FETs) have been developed rapidly and are currently considered as an alternative for postsilicon electronics. In this study, polypyrrole-converted nitrogen-doped few-layer graphene (PPy-NDFLG) was grown on Cu substrate by chemical vapor deposition combined with vapor deposition polymerization and then transferred onto a flexible substrate. Furthermore, antivascular endothelial growth factor (VEGF) RNA aptamer conjugated PPy-NDFLG was integrated into a liquid-ion gated FET geometry to fabricate a high-performance VEGF aptamer-based sensor. Field-induced high sensitivity was observed for the analyte-binding events, eventually leading to the recognition of the target molecules at an unprecedentedly low concentration (100 fM). Additionally, the aptasensor had excellent reusability, mechanical bendability, and durability in the flexible process. The developed methodology describes, for the first time, the fabrication of N-doped graphene using conducting polymers including heteroatoms in their structures as the carbonization precursor and demonstrates its use in a high-performance, flexible FET-type aptasensor to detect vascular endothelial growth factor as a cancer biomarker. © 2012 American Chemical Society. Source


Yu H.,Advanced Center for Energy | Kim D.Y.,Advanced Center for Energy | Lee K.J.,Chungnam National University | Oh J.H.,Advanced Center for Energy
Journal of Nanoscience and Nanotechnology | Year: 2014

This paper reviews the recent research and development of one-dimensional (1D) organic nanomaterials synthesized from organic semiconductors or conducting polymers and their applications to optoelectronics. We introduce synthetic methodologies for the fabrication of 1D single-crystalline organic nanomaterials and 1D multi-component organic nanostructures, and discuss their optical and electrical properties. In addition, their versatile applications in optoelectronics are highlighted. The fabrication of highly crystalline organic nanomaterials combined with their integration into nanoelectronic devices is recognized as one of the most promising strategies to enhance charge transport properties and achieve device miniaturization. In the last part of this review, we discuss the challenges and the perspectives of organic nanomaterials for applications in the next generation soft electronics, in terms of fabrication, processing, device integration, and investigation on the fundamental mechanisms governing the charge transport behaviors of these advanced materials. © 2014 American Scientific Publishers. Source


Jo Y.,Ulsan National Institute of Science and Technology | Jo Y.,Advanced Center for Energy | Jung C.-L.,Ulsan National Institute of Science and Technology | Jung C.-L.,Advanced Center for Energy | And 10 more authors.
Electrochimica Acta | Year: 2012

In dye-sensitized solar cells (DSSCs), dye coating is one of the important factors in the fabrication process. Dye coating takes more than several hours in the conventional methods when Ru-based dyes, especially N719, the main dye for DSSC applications, are applied. In this paper, we applied a new coating system to maximize the adsorption reaction between the dye and TiO 2 nanocrystalline surface. Applied solvents are from mono alcohol to triols with various temperatures and concentrations of the dye. According to our experiments, dye coating time can be shortened down from several hours to 3 min. To compare the new system to the conventional system, various analysis tools were applied for further investigation. The new solvent system with ethylene glycol, gives many advantages such as saving solvent usage, short coating time, and easy procedure for mass fabrication without toxicity. © 2012 Elsevier Ltd. All rights reserved. Source

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