%0 Journal Article
%T Aqueous Medium Synthesis Route for Randomly Stacked Molybdenum Disulfide
%A Pravas Kumar Panigrahi
%A Amita Pathak
%J Journal of Nanoparticles
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/671214
%X Synthesis of poorly crystalline, randomly oriented rag-like structures of molybdenum disulfide has been reported starting from aqueous solutions of ammonium molybdate, and thioacetamide in presence of sodium dodecyl sulfate via calcination of the amorphous precipitates, obtained through acidification of the in situ generated intermediate of ammonium tetrathiomolybdate. X-ray photoelectron spectroscopy, UV-visible spectroscopy, and X-ray diffraction of the calcined samples reveal the formation of single-phase MoS2, while the amorphous precipitates have been found to be a mixture of Mo2S5, MoS3, and a trace amount of H2MoS4. Highly folded and disordered layers of rag-like MoS2 have been confirmed through high-resolution transmission electron microscopy. The electrical conductivity for the cold pressed pellet of the MoS2 sample is found to be significantly higher than that of 2H-MoS2 and increases further on annealing. 1. Introduction Molybdenum disulfide (MoS2) is a hexagonal layer structured material. The MoS2 layers, each of which consists of a layer of molybdenum atoms sandwiched between two layers of sulfur atoms, are connected by weak van der Waals force. Due to the weak interactions between the sheets of sulfur atoms, MoS2 exhibits excellent lubrication property [1, 2]. It also finds applications as electrode in high-density lithium batteries [3], solar cells [4] in form of thin films, and as intercalation host to produce new materials [5, 6]. From a catalytic point of view, MoS2 possesses outstanding properties towards methanation of CO with hydrogen [7] and hydrodesulfurization reaction for removal of sulfur compounds from crude oil [8, 9]. It has been found that the catalytic activity of MoS2 strongly depends on the number of coordinatively unsaturated sites [10]. Thus, the catalytic activity of MoS2 is influenced by the particle size as well as the number of layers, demonstrating that the morphology is also an important parameter for such applications. Till date, MoS2 powders with different morphologies have been synthesized through a wide range of methods, such as thermal decomposition of ammonium tetrathiomolybdate or amorphous MoS3 [11, 12], reaction of stoichiometrically mixed molybdenum and sulfur powders in vacuum at high temperature [13], and gas-phase reactions of molybdenum oxides with H2S under reducing atmosphere [14, 15]. There are also reports on the use of other high-energy sources like laser [16], electron beam [17], and ¦Ã-radiation [18] for the synthesis of nanotubes, fullerene-like, and other curved nanostructures of MoS2. As an
%U http://www.hindawi.com/journals/jnp/2013/671214/