Synthesis Methods of Two-Dimensional MoS2: A Brief Review

Abstract

Molybdenum disulfide (MoS 2) is one of the most important two-dimensional materials after graphene. Monolayer MoS 2 has a direct bandgap (1.9 eV) and is potentially suitable for post-silicon electronics. Among all atomically thin semiconductors, MoS 2 's synthesis techniques are more developed. Here, we review the recent developments in the synthesis of hexagonal MoS 2 , where they are categorized into top-down and bottom-up approaches. Micromechanical exfoliation is convenient for beginners and basic research. Liquid phase exfoliation and solutions for chemical processes are cheap and suitable for large-scale production; yielding materials mostly in powders with different shapes, sizes and layer numbers. MoS 2 films on a substrate targeting high-end nanoelectronic applications can be produced by chemical vapor deposition, compatible with the semiconductor industry. Usually, metal catalysts are unnecessary. Unlike graphene, the transfer of atomic layers is omitted. We especially emphasize the recent advances in metalorganic chemical vapor deposition and atomic layer deposition, where gaseous precursors are used. These processes grow MoS 2 with the smallest building-blocks, naturally promising higher quality and controllability. Most likely, this will be an important direction in the field. Nevertheless, today none of those methods reproducibly produces MoS 2 with competitive quality. There is a long way to go for MoS 2 in real-life electronic device applications.

Recent Progress on Irradiation-Induced Defect Engineering of Two-Dimensional 2H-MoS2 Few Layers

“…Because of the novel properties and wide applications of 2H-MoS 2 2D layers, MoS 2 2D layers have been prepared by various physical or chemical methods [41,[44][45][46][66][67][68][69]. Individual MoS 2 layers were usually obtained by the micromechanical cleavage technique [70] because of weak interactions between sulfur layers and strong intralayer interactions of MoS 2 bulks.…”

Long‐Term Stability Control of CVD‐Grown Monolayer MoS2

“…Aspects related to self‐limiting, controllable, homogeneous, and large scale growth remain as main challenges in the growth of TMD layers . To this end, micromechanical exfoliation (ME), liquid phase exfoliation (LPE), physical vapor deposition (PVD), solution chemical process (SCP), chemical vapor deposition (CVD), molecular beam epitaxy (MBE), and metalorganic chemical vapor deposition (MOCVD) have been studied to obtain monolayer TMDs specifically for MoS 2 . Although the growth mechanism of these materials has not been fully well understood large scale film and/or flake growth is achieved to some extend by the mentioned methods including cost effective CVD systems and more complicated MOCVD systems …”

Ultrathin layered MoS2 nanosheets with rich active sites for enhanced visible light photocatalytic activity

“…10 Additionally, there are numerous reports that have demonstrated enhanced photocatalytic activity by increasing the exposed edge active sites, and this method has been utilized in applications such as hydrogen evolution reaction (HER) in the MoS 2 disordered layers, as reported by Xie et al 11 The structural and morphological features extensively depend on the synthetic strategies for MoS 2 . Consequently, various methods have been developed to synthesize MoS 2 , such as the evaporation method, 20,21 precipitation method, 22 hydrothermal method, [23][24][25][26][27][28] and exfoliation method. 29,30 Among these methods, the hydrothermal method is the most facile to synthesize MoS 2 with layered structures and high crystallinity.…”