A study on surfactant-free growth of silver-carbon nanocables by H 2 SO 4 -mediated hydrothermal process
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HongLing Liu Institute of Molecular and Crystal Engineering, School of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, China
JunHua Wub) Pioneer Research Center for Biomedical Nanocrystals, Korea University, Seongbuk-Gu, Seoul 136-713, Korea (Received 23 March 2011; accepted 22 July 2011)
We study the one-pot facile hydrothermal growth of ultralong silver–carbon (Ag–C) nanocables with Ag nanowires as the cores and carbon as the sheaths through the mediation of H2SO4 and without using an organic surfactant. In the investigation, Ag–C nanostructures were systematically and extensively examined as a function of both temperature and H2SO4 concentration to locate the optimal conditions for preparing ultralong, robust, and uniform Ag–C coaxial nanocables at T 5 180 °C and 0.5 M H2SO4. The characterization clearly demonstrated a simple, efficient, and surfactant-free synthesis of Ag–C nanocables. In the hydrothermal process, glycerol acts as both reducing agent and carbon source, while H2SO4 mediates the directional growth of the silver nanowire core and assists the deposition of carbon. Moreover, the nanocables manifest unusual ferromagnetism at room temperature and a plausible mechanism of forming Ag–C nanocables was proposed as a result of the chain-like hydrogen sulfate compounds owing to the H2SO4 mediation.
I. INTRODUCTION
Quasi-one-dimensional (1D) nanostructures of metals have drawn considerable attention because of their unique physical properties and potential applications in fabricating nanoscale electronic devices as both interconnectors and active components.1,2 Among the 1D nanostructure candidates, metal nanowires have attracted particular interest in that they are expected to prospectively play an imperative role in fabricating nanoscale electronic,3 optoelectronic,4 or magnetic devices.5 They offer an ideal model system to experimentally investigate physical phenomena such as quantized conductance and localization effects.6 The function of silver in particular has been extensively exploited in photonics,3,7 electronics,8 photography,9 catalysis,10 biological labeling,11 and surface-enhanced Raman scattering.12 When silver takes the form of 1D nanostructures, its performance in many aspects could be potentially enhanced.3 On the nanometer scale, however, metallic materials are normally sensitive to air and moisture, so mounting an inertial sheath can protect the liable material, avoiding the degradation of performance of nanodevices.
Address all correspondence to these authors. a) e-mail: [email protected] b) e-mail: [email protected] DOI: 10.1557/jmr.2011.251 2780
J. Mater. Res., Vol. 26, No. 21, Nov 14, 2011
http://journals.cambridge.org
Downloaded: 16 Mar 2015
Carbon, from diamond, graphite (graphene), fullerenes, nanotubes to diamond-like ultrathin films, is a versatile, fascinating material of fundamental value and technological importance.13–16 For its inertness, the material as coating offers proper protection of active substances. Nanoengineering the two materia
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