Fullerene-Like (IF) Nb_xMo_1-xS₂ Nanoparticles

Abstract

IF-Mo1-xNbxS2 nanoparticles have been synthesized by a vapor-phase reaction involving the respective metal halides with H2S. The IF-Mo1-xNbxS2 nanoparticles, containing up to 25% Nb, were characterized by a variety of experimental techniques. Analysis of the powder X-ray powder diffraction, X-ray photoelectron spectroscopy, and different electron microscopy techniques shows that the majority of the Nb atoms are organized as nanosheets of NbS2 within the MoS2 host lattice. Most of the remaining Nb atoms (3%) are interspersed individually and randomly in the MoS2 host lattice. Very few Nb atoms, if any, are intercalated between the MoS2 layers. A sub-nanometer film of niobium oxide seems to encoat the majority of the nanoparticles. X-ray photoelectron spectroscopy in the chemically resolved electrical measurement mode (CREM) and scanning probe microscopy measurements of individual nanoparticles show that the mixed IF nanoparticles are metallic independent of the substitution pattern of the Nb atoms in the lattice of MoS2 (whereas unsubstituted IF-MoS2 nanoparticles are semiconducting). Furthermore the IF-Mo1-xNbxS2 nanoparticles are found to exhibit interesting single electron tunneling effects at low temperatures.

Electronic properties of the MoS2-WS2heterojunction

“…The properties of bulk MoS 2 and its nanostructures, such as nanotubes, 15,16 fullerenes, 17 and nanoislands, 18 have been studied for a long while, including even chemically exfoliated single planes. 19 More recently, the study of electronic and optoelectronic devices based on a single MoS 2 layer has taken the impetus for several reasons.…”

Ab initiostudy of bilateral doping within theMoS2-NbS2system

“…Recently, inorganic fullerene-like Mo 1−x Nb x S 2 nanoparticles have been synthesized and characterized 21 and we expect that the catalytic activity of the mixed phase might be enhanced in the nanoparticles due to a high surface to volume ratio.…”

“…However, current analytical techniques can not easily detect the exact arrangement of atoms in mixed systems, and so neither doping by inter-layer intercalation nor intraplane substitution can be excluded. 12,21,22 Complementary structural information can be provided by simulations using ab-initio techniques.…”

Gas-phase synthesis of inorganic fullerene-like structures and inorganic nanotubes

“…One of the major achievements of this method has been that the electronic properties of the IF nanoparticles could be successfully modified with some control by enabling doping of the nanoparticles [55,56]. Success in achieving doping to modify the electronic properties leads to other interesting possibilities.…”

“…This would be more difficult to achieve starting from the oxides, due to complexities of the phase diagram [55]. The effect of Nb substitution on the electronic structure of MoS 2 has been investigated theoretically using density functional tight binding method (DFTB) [56].…”