Thermolytic synthesis of cobalt and cobalt sulfide nanoparticles using Cobalt(II) NO Schiff base complexes as single molecular precursors

Two novel N^O-type Schiff base ligands and the corresponding Co(II) complexes are reported. Thermo-gravimetric analysis indicated that the complexes are potential molecular precursors for the fabrication of cobalt andcobalt-containing nanomaterials. The significant difference in the thermal decomposition profiles is recognized as aninfluence of structural differences on the complexes. Thus, the complexes were thermally decomposed using the melt andhot injection methods to examine the properties of the obtained cobalt and cobalt sulfide nanoparticles, respectively.The reaction parameters employed during the fabrication processes, in addition to structural differences, influencedthe morphological and crystallographic phases and magnetic properties of the synthesized nanoparticles. We have in-vestigated the morphological properties and the crystallographic phase compositions of the nanoparticles by variouselectron microscopy and diffraction techniques, as well as energy-dispersive X-ray spectroscopy. The melt reactionsproduced phase-pure cobalt nanoparticles, which exhibit ferromagnetic behavior. The hot injection method utilized 1-dodecanethiol (DDT) as both sulfur source and capping agent. We indexed the DDT-capped cobalt sulfide nanoparticlesto cubic Co9S8and Co3S4phases using powder X-ray diffraction, high-resolution transmission electron microscopyimaging, and selected area electron diffraction. The crystallite sizes for Co9S8and Co3S4nanoparticles, based on theScherrer equation, were 12.4 nm and 14.1 nm, respectively. We find significant differences in the magnetic properties,attributed to nonmagnetic inclusions and vacancies due to the presence of S atoms.

Keywords

Cobalt, cobalt sulfide, melt, 1-dodecanethiol, Schiff base

URI

http://hdl.handle.net/20.500.11810/5200

Collections

Department of Chemistry

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