12033-29-3Relevant academic research and scientific papers
Synthesis and characterization of molybdenum disulphide formed from ammonium tetrathiomolybdate
Wang,Skeldon,Thompson,Wood
, p. 497 - 502 (1997)
An investigation has been carried out into the possibility of in situ formation of MoS2 within porous anodic films on aluminium, to improve subsequent tribological behaviour, by re-anodizing in thiomolybdate electrolyte. Acidification of thiomolybdate was employed to simulate the conditions for formation of the sulphide at the anodic film/electrolyte interface, followed by appropriate vacuum heat treatments to study possible temperature effects on the sulphide due to either friction or Joule heating during anodizing. The products of both acidification and heat treatment, characterized by X-ray powder diffraction and scanning electron microscopy, were compared with those formed by direct thermal decomposition of ammonium tetrathiomolybdate crystals. The precipitate formed by acidification was mainly amorphous molybdenum trisulphide (MoS3), which on heat treatment at 450 and 850°C yielded 3R-MoS2. 3R-MoS2 also formed by the thermal decomposition of thiomolybdate crystals. Thermogravimetric and differential thermal analyses showed that the decomposition of MoS3 to MoS2 occurred in the range 220-370°C and revealed the sequence of reaction steps. The findings suggest that mainly amorphous MoS3 is formed as a consequence of changes in the pH of the film/electrolyte interface during re-anodizing but the product is relatively easily transformed to crystalline MoS2 on moderate heating which may occur during wear processes.
Electron Spin Resonance of Paramagnetic Species as a Tool for Studying the Thermal Decomposition of Molybdenum Trisulfide
Busetto, Luigi,Vaccari, Angelo,Martini, Giacomo
, p. 1927 - 1930 (1981)
ESR has been used in the study of the irreversible thermal decomposition of molybdenum trisulfide to disulfide in the range 180-600 deg C.Three paramagnetic species were observed: (a) MoS3+, whose magnetic parameters were different depending on which phase, either MoS3 or MoS2, was predomonant; (b) sulfur chain radical, due to loss of sulfur during the decomposition; (c) MoO3+, due to a very low degree of contamination of the system with oxygenated Mo species.The nature of these species is discussed.The intensity and the line shape of signals for a and b as a function of the treatment temperature of the samples were used to follow the decomposition steps.The ESR results have been correlated with X-ray and analytical data.
The influence of reducing and sulfiding conditions on the properties of unsupported MoS2-based catalysts
Afanasiev, Pavel
, p. 269 - 280 (2010)
Unsupported MoS2 catalysts were obtained from the decomposition of ammonium tetrathiomolybdate (ATM) at variable temperatures (400-700 °C) and under different gas compositions, from pure H2S to pure H2. The catalysts were further studied in the non-promoted state or promoted by Ni and Co. Catalytic activity and selectivity were studied in the model reaction of thiophene hydrodesulfurization (HDS). Surface areas, crystalline phase and particle size distributions were determined by Brunauer-Emmet-Teller (BET), X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. A comparison of average values calculated from these techniques has enabled the understanding of the morphology of the solids. The catalysts were characterized before and after catalytic tests by X-ray photoelectron spectroscopy (XPS), laser Raman spectroscopy (LRS) and temperature-programmed reduction (TPR). Comparison of catalytic activity trends with the results of the characterizations show that over-stoichiometric sulfur, present in the fresh catalysts in the form of edge-located S22 - species, plays a key role for the activity of unsupported MoS2 and for its ability to be promoted. Direct hydrogenation (HYD) of thiophene to butane occurs presumably with the participation of -SH groups, produced from the opening of S-S bridges by hydrogen. Whatever the gas atmosphere, any treatment leading to the removal of over-stoichiometric sulfur leads to a decrease in HYD selectivity. Thus, very similar catalytic properties were observed for MoS2 annealed at 700 °C in pure H2, H2S or N2 gases. Ni and Co introduced by means of reflux with acetylacetonates, gave identical promotion trends for all the MoS2 samples. The solids treated in pure H2S could not take up promoter atoms at the edges, whereas for the H2-reduced samples high promotion levels were achieved. The degree of stacking does not seem to have a significant impact on the thiophene HDS activity and selectivity of the unsupported MoS2 catalysts.
Lineshapes of ESR signals and the nature of paramagnetic species in amorphous molybdenum sulfides
Deroide,Bensimon,Belougne,Zanchetta
, p. 853 - 853 (1991)
Amorphous and poorly crystallized molybdenum sulfides were studied by ESR. Qualitative analysis of the spectra suggested the presence of three paramagnetic species. A simulation of the ESR spectra was attempted. ESR lines were determined over the stoichiometric range MoS3 → MoS2. A good representation of the main part of the experimental lines was obtained. There was no significant variation of the g values of the various components of the spectra during the transformation from Mo3to Mo2. The first signal was attributed to sulfur centers. The other two signals were assigned to metal centers.
SYNTHESIS OF NOVEL MOLYBDENUM CHALCOGENIDES.
Schleich,Martin
, p. 359 - 364 (1985)
Recently, there has been substantial interest in using molybdenum chalcogenides as active cathodes in lithium batteries. It has been observed that the structural make-up of the material (crystalline or amorphous) is often of critical importance in the abi
Aqueous solution processed MoS3as an eco-friendly hole-transport layer for all-inorganic Sb2Se3solar cells
Ma, Yuyuan,Yin, Yiwei,Li, Gang,Lian, Weitao,Zhang, Jianwang,Tang, Rongfeng,Ju, Huanxin,Chen, Tao
, p. 15173 - 15176 (2020)
Here we report a solution processed environmentally friendly MoS3 hole-transport material for Sb2Se3 solar cells, where MoS3 exhibits a matched energy level relative to Sb2Se3. In the synthesis, H2S produced by the thermal decomposition of (NH4)2MoS4 is found to efficiently eliminate the antimony oxide impurity formed on the Sb2Se3 surface. Finally, the all-inorganic Sb2Se3 solar cell delivers an efficiency of 6.86% with excellent stability. This journal is
Simple solution route to uniform MoS2 particles with randomly stacked layers
Li, Qing,Li, Ming,Chen, Zhiqian,Li, Chunmei
, p. 981 - 986 (2004)
MoS2 particles of uniform size (ca. 70nm) consisting of random and loosely stacked layers have been synthesized from hydrazine solution with (NH4)2Mo3S13 as the precursor at 180°C for 16h under hydrothermal conditions. The particles were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HREM). The influences of reaction conditions are discussed while a mechanism is proposed to explain the formation of this peculiar morphology.
MoS3 thin film cathodes prepared by chemical vapor deposition
Schleich,Chang,Barberio,Hanson
, p. 3274 - 3278 (1989)
Amorphous molybdenum trisulfide (MoS3) is a promising candidate as a host material in a lithium insertion battery. Thin films of MoS3 have been prepared by chemical vapor deposition from molybdenum hexafluoride (MoF6) and hexamethyldisilthiane (HMDST). Continuous, adherent films were obtained at deposition temperatures in the range of 150° to 400°C on aluminum, nickel, silica, and alumina substrates. Infrared analyses indicate that deposition temperatures between 200° and 250°C produce the purest films. The best electrochemical performance was achieved on films deposited in the range of 210°C to 240°C, which corresponded to those films analytically determined to be MoS3.
Formation and catalytic properties of edge-bonded molybdenum sulfide catalysts on TiO2
Araki, Yasuhiro,Honna, Kosaku,Shimada, Hiromichi
, p. 361 - 370 (2002)
The effect of preparation conditions (calcination atmosphere, sulfidation atmosphere, and sulfidation temperature) on the orientation of MoS2 clusters on TiO2 supports was studied. Edge-bonded MoS2 clusters formed when the catalyst was sulfided in a flow of H2S/N2 at 573 or 673 K. However, when sulfided in H2S/N2 at higher temperatures than 773 K, the edge-bonded MoS2 clusters transformed to highly aggregated basal-bonded MoS2 clusters. Catalytic activity tests, using hydrogenation of 1-methylnaphthalene as a model test reaction, revealed that the turnover frequency on the catalyst with edge-bonded MoS2 clusters prepared by sulfiding at 573 K in H2S/N2 was higher than that on the catalyst with basal-bonded MoS2 clusters prepared by sulfiding in H2S/H2.
Electron Spin Resonance of Water Adsorption on Amorphous Molybdenum Sulfide
Bensimon, Y.,Belougne, P.,Giuntini, J. C.,Zanchetta, J. V.
, p. 2754 - 2757 (1984)
The interaction between molybdenum trisulfide and water vapor has been studied by ESR.The trisulfide was obtained from the thermal decomposition of (NH4)2MoS4.The observed spectra are characteristic of two distinct paramagnetic species.The first one corre
