Chemical vapor deposition of clean and pure MoS₂ crystals by the inhibition of MoO_3−x intermediates

Abstract

Molybdenum disulfide (MoS2) synthesized by Chemical Vapor Deposition (CVD) is commonly accompanied by some intermediate products in the form of MoO3-x, and causing MoS2-MoO3-x hybrids with diverse structures. In this...

Controlled growth of 3D assemblies of edge enriched multilayer MoS2 nanosheets for dually selective NH3 and NO2 gas sensors

“…Next, sulfur vapor will penetrate to the first top layers of MoO 3Àx quadrilaterals and will change them from MoO 3Àx to MoS 2 . 27,43,53 This reaction pathway is supported by Fig. 6(e).…”

“…Many studies in the literature reported the presence of these intermediate phases when the MoO 3 precursor is used and this is an issue that should be addressed in the future. Based on the literature, 43 MoO 3 is first reduced to MoO 3− x and with further sulfur it is converted to MoS 2 . Equations (eqn (3) and (4)) describe the conceivable chemical reaction that can occur during the synthesis.2MoO 3 + x S → 2MoO 3− x + x SO 2 2MoO 3− x + (7 − x )S → 2MoS 2 + (3 − x )SO 2 …”

Oxygen-Assisted Anisotropic Chemical Etching of MoSe2 for Enhanced Phototransistors

“…(1) Hydrogen used to be regarded as an effective promoter in etching graphene because it is required for the reduction of methane during graphene growth . In terms of the growth of TMDs, hydrogen is necessary for the deposition of MSe 2 (M = transition metals) but is not necessary for the generation of MS 2 . Therefore, the mechanisms of hydrogen promoting the etching processes of these two types of TMDs materials are totally different, and hydrogen cannot be proposed as a universal etching promoter that shares the same etching mechanism.…”

“…40 In terms of the growth of TMDs, hydrogen is necessary for the deposition of MSe 2 (M = transition metals) 41 but is not necessary for the generation of MS 2 . 42 Therefore, the mechanisms of hydrogen promoting the etching processes of these two types of TMDs materials are totally different, and hydrogen cannot be proposed as a universal etching promoter that shares the same etching mechanism. (2) Researchers have previously investigated the role of oxygen in the growth of TMDs and suggested that, beyond a certain threshold, oxygen will change from a growth promoter to an etching promoter.…”

Impact Electrochemistry of MoS2: Electrocatalysis and Hydrogen Generation at Low Overpotentials

“…Since the edge sites of MoS 2 are catalytically active and the basal sites are inert, , recent research has been focused on how to either create more active edge sites of MoS 2 or improve the activity of the basal planes. Of the former, chemical strategies such as doping, or structural properties such as crystallinity and nanostructuring have been investigated in an effort to expose a higher number of active edge sites. − To achieve these structures, energy intensive techniques are often required such as atomic layer deposition, chemical vapor deposition and hydrothermal methods. − Electrochemical methods such as electrodeposition have also been reported to produce MoS 2 with increased catalytic properties. ,− The nanoscale forms of MoS 2 have been gaining more recognition due to a greater surface area and a larger percentage of exposed active edge sites. Studies have shown an improved catalytic activity toward HER for nanostructured forms of molybdenum disulfide as compared to its bulk crystalline form …”