Group 6 transition metal dichalcogenides (G6-TMDs), most notably MoS2, MoSe2, MoTe2, WS2 and WSe2, constitute an important class of materials with a layered crystal structure. Various types of G6-TMD nanomaterials, such as nanosheets, nanotubes and quantum dot nano-objects and flower-like nanostructures, have been synthesized. High thermodynamic stability under ambient conditions, even in atomically thin form, made nanosheets of these inorganic semiconductors a valuable asset in the existing library of two-dimensional (2D) materials, along with the well-known semimetallic graphene and insulating hexagonal boron nitride. G6-TMDs generally possess an appropriate bandgap (1–2 eV) which is tunable by size and dimensionality and changes from indirect to direct in monolayer nanosheets, intriguing for (opto)electronic, sensing, and solar energy harvesting applications. Moreover, rich intercalation chemistry and abundance of catalytically active edge sites make them promising for fabrication of novel energy storage devices and advanced catalysts. In this review, we provide an overview on all aspects of the basic science, physicochemical properties and characterization techniques as well as all existing production methods and applications of G6-TMD nanomaterials in a comprehensive yet concise treatment. Particular emphasis is placed on establishing a linkage between the features of production methods and the specific needs of rapidly growing applications of G6-TMDs to develop a production-application selection guide. Based on this selection guide, a framework is suggested for future research on how to bridge existing knowledge gaps and improve current production methods towards technological application of G6-TMD nanomaterials.

Group 6 transition metal dichalcogenide nanomaterials: synthesis, applications and future perspectives

A synoptic review of MoS2: Synthesis to applications

Numerous efforts in improving the hydrogen evolution reaction (HER) performance of transition metal dichalcogenides mostly focus on active sites exposing, vacancy engineering, and phase engineering...

Magnetic Enhancement for Hydrogen Evolution Reaction on Ferromagnetic MoS2 Catalyst.

We report on a high-performance NO2 sensor based on a one dimensional MoS2 nanowire (NW) network The MoS2 NW network was synthesized using chemical transport reaction through controlled turbulent vapor flow The crystal structure and surface morphology of MoS2 NWs were confirmed by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy Further, the sensing behavior of the nanowires was investigated at different temperatures for various concentrations of NO2 and the sensor exhibited about 2-fold enhanced sensitivity with a low detection limit of 46 ppb for NO2 at 60 °C compared to sensitivity at room temperature Moreover, it showed a fast response (16 s) with complete recovery (172 s) at 60 °C, while sensitivity of the device was decreased at 120 °C The efficient sensing with reliable selectivity toward NO2 of the nanowires is attributed to a combination of abundant active edge sites along with a large surface area and tuning of the potential barrier 

High performance NO2 sensor using MoS2 nanowires network

In the recent years, transition-metal dichalcogenides such as MoS2 have attracted considerable attention owing to their unique structure and electronic properties. Chemical vapor deposition (CVD) is a popular method for producing MoS2 flakes with different shapes. Here, we report an effective method for achieving a broad range of shape evolution in CVD-grown monolayer MoS2 flakes. By controlling the S and MoO3 temperatures, the shape of the monolayer MoS2 flakes was varied from hexagonal to triangular via intermediate shapes such as truncated and multi-apex triangles. The shape evolution of the MoS2 flakes can be explained by introducing the term “nominal Mo:S ratio”, which refers to the amount of loaded MoO3 and evaporated S powders. By using the nominal Mo:S ratio, we predicted the potential reaction atmosphere and effectively controlled the actual proportion of MoO3−x
 with respect to S in the growth region, along with the growth temperature. From the systematic investigation of the behavior of the shape evolution, we developed a shape-evolution diagram, which can be used as a practical guide for producing CVD-grown MoS2 flakes with desired shapes.

Effective shape-controlled growth of monolayer MoS2 flakes by powder-based chemical vapor deposition

Influences of carrier gas flow rate on the morphologies of MoS2 flakes

We describe a single step route for the synthesis of MoS2 wires using a chemical vapour deposition (CVD) method. By tuning the CVD growth parameters, the horizontally oriented MoS2 nanowires on SiO2/Si substrate can be synthesized successfully. The MoS2 nanowire has height of about 93 nm and width of about 402 nm with multilayer structure. Good local photoluminescence (PL) properties can be observed for these horizontal MoS2 nanowires. The successful fabrication and prominent PL effect of the horizontal MoS2 nanowires provide potential applications for the MoS2-based in planar devices.

Horizontal growth of MoS2 nanowires by chemical vapour deposition

Morphology evolution of MoS2 nanorods grown by chemical vapor deposition

The precise control of the morphology of monolayer MoS2 is of particular importance for their potential applications and device performance. In this work, we present an experimental method to study the shape evolution of the chemical vapor deposition (CVD) grown MoS2 flakes. We observed that the morphology of monolayer MoS2 flakes transformed from truncated triangular shape to triangular shape by increasing the stoichiometric ratio of S:Mo, and consequently tailor the optical properties of MoS2 flakes. The results suggest the possibility to engineer the morphology of monolayer MoS2 by adjusting the chemical environment during growth.

Shuming Han

Papers

Influences of carrier gas flow rate on the morphologies of MoS2 flakes

Horizontal growth of MoS2 nanowires by chemical vapour deposition

Morphology evolution of MoS2 nanorods grown by chemical vapor deposition

Morphology engineering of monolayer MoS2 by adjusting chemical environment during growth

Morphology evolution of MoS2: From monodisperse nanoparticles to self-assembled nanobelts