Low Melting Metal Catalyzed Growth of Tin Disulfide Nanotubes

  • PDF / 647,821 Bytes
  • 6 Pages / 595 x 842 pts (A4) Page_size
  • 18 Downloads / 174 Views

DOWNLOAD

REPORT


1178-AA03-19

Low Melting Metal Catalyzed Growth of Tin Disulfide Nanotubes Aswani Yella, Enrico Mugnaioli, Martin Panthoefer, Ute Kolb, Wolfgang Tremel* Institute für Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany ABSTRACT We report here the synthesis of tin disulfide nanotubes by a vapour liquid solid growth using bismuth, a low melting metal, as a catalyst. The reaction was carried out in a single step process by heating SnS2 and bismuth in a horizontal tube furnace at 800oC. TEM analysis allowed proposing a plausible mechanism for the formation of SnS2 nanotubes. Pure material could be obtained by optimizing the reaction based on a product analysis using powder X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) combined with energy dispersive X-ray spectroscopy (EDX). INTRODUCTION In addition to carbon nanotubes, non-carbon nanostructures have attracted much attention over the past few years. In particular, and due to their unusual geometry and promising physical properties, inorganic fullerene nanostructures have become one of the key topics in nanoscale research since the first report on WS2 nanotubes by Tenne et al. in 1992.[1] Various approaches to other nanotubes, such as NiCl2,[2] VS2,[3], TiS2,[4] or InS[5] have also been reported, which implies that substances possessing layered structures may form nanotubes under favorable conditions. Still, the synthesis of chalcogenide nanotubes and nested nanoparticles is difficult because their formation requires the release of considerable strain energy against surface curvature and wall thickness.[6] Layered chalocogenides (MQ2, M = Mo, W, Re or Sn) are triple-layer structures in which one metal layer is sandwiched between two chalcogenide layers.[7] The two most efficient synthetic approaches are the reductive sulfidization of oxide films[8] or particles[9] or the template deposition in porous alumina.[10] Other synthetic approaches make use of the direct pyrolysis of artificial lamellar mesostructures,[11] sonoelectrochemical bath reactions,[12] or electron beam irradiation in the electron transmission microscope.[13] A particular problem in the synthesis of fullerene-type nanoparticles and of nanotubes is that they are high-temperature and low-pressure phases. High preparation temperatures are needed to interconnect the edges of single layers fragments through the formation of point defects which provide curvature to the otherwise flat slabs. The instable reaction intermediates have to be trapped before they can polymerize in follow-up reactions, a concept that proved for example fruitful in matrix isolation spectroscopy. In practice, dilution, i.e. low pressure, prevents the formation of larger aggregates in the gas phase. In fact, most successful strategies for the formation of nanotubes (and fullerene-type species) rely on gas phase reactions, where the reactive gas phase species are trapped by “shock freezing”. In the case of tin disulfide, the decomposition temperat