MoS₂FULLERENE-LIKE NANOPARTICLES AND NANOTUBES USING GAS-PHASE REACTION WITHMoCl₅

Abstract

Inorganic fullerene-like (IF) nanoparticles of MoS 2 were synthesized using gas-phase reaction starting from MoCl 5 and H 2 S . The IF- MoS 2 nanoparticles are spherical and in some cases faceted with diameters in general ranging between 20 and 80 nm. The IF- MoS 2 nanoparticles have large hollow cores, filled in some cases with amorphous material. Various parameters have been investigated to understand the growth and formation of the IF- MoS 2 nanoparticles. The parameters that have been studied include flow rates of the various carrier gases, temperature at which the reaction was carried out, time of the reaction and heating of the precursor material. The best set of conditions wherein maximum yields of the IF- MoS 2 nanoparticles are obtained have been identified. Additionally, annealing the as-obtained samples or heating them in a mixture of H 2 along with H 2 S improves the crystallinity and reduces the amorphous material filling in the core. Apart from the fullerene-like nanoparticles under certain experimental conditions nanotubes of MoS 2 have also been obtained nonetheless in small yields.

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

“…It can thus be concluded that the larger IF nanoparticles are either transformed into platelets or do not form at all at higher temperatures, while smaller IF nanoparticles are more stable. A similar observation was reported for the synthesis of IF-MoS 2 and IF-WS 2 nanoparticles, where, above the optimum temperatures of synthesis, the resulting product was dominated by platelets [42,43]. In these cases, however, nanotubes of MoS 2 and WS 2 were also obtained at higher temperatures of synthesis [42,43].…”

“…Experimental studies have confirmed this dominance at low temperatures and in excess sulfur regime [48][49][50]. The development of an IF structure displaying improved crystallinity with rising temperature has been studied previously for the syntheses of IF-NbS 2 , IF-TaS 2 and IF-MoS 2 [40][41][42][43][44] (Scheme 2, II → IV). At higher reaction temperatures, the 2H-MS 2 polytype predominates.…”

“…The experimental set-up that was used for this synthesis involved a two-stage furnace in which the precursor was heated in the auxiliary furnace ( Fig. 3b), and the reaction occurred in the hot zone of the main vertical furnace [42]. A schematic of the experimental set-up is shown in Fig.…”

“…Here again various parameters have been studied to understand the growth and formation of the IF-WS 2 nanoparticles and nanotubes. In the case of the synthesis of the IF-WS 2 nanoparticles and nanotubes, in addition to the vertical reactor [42], a horizontal reactor (Fig. 6) was also employed [43].…”

“…On heating the precursor MCl n under reducing conditions in the presence of the sulphidizing agent, the first step would involve the formation of M species (I). This species could be of the type MCl n S x (MCl n → MCl n S x ) [40][41][42][43][44]. From there, the reaction proceeds to the formation of a pure MS 2 phase.…”