Two-dimensional (2D) molybdenum disulfide (MoS₂) holds great potential for various applications such as electronic devices, catalysis, lubrication, anti-corrosion and so on. Thermal evaporation is a versatile thin film deposition technique, however, the conventional thermal evaporation techniques face challenges in producing uniform thin films of MoS₂ due to its high melting temperature of 1375 °C. As a result, only thick and rough MoS₂ films can be obtained using these methods. To address this issue, we have designed a vacuum thermal evaporation system specifically for large-scale preparation of MoS₂ thin films. By using K₂MoS₄ as the precursor, we achieved reliable deposition of uniform polycrystalline MoS₂ thin films with a size of 50 mm × 50 mm and controllable thickness ranging from 0.8 to 2.4 nm. This approach also allows for patterned deposition of MoS₂ using shadow masks and sequential deposition of MoS₂ and tungsten disulfide (WS₂), similar to conventional thermal evaporation techniques. Moreover, we have demonstrated the potential applications of the obtained MoS₂ thin films in field effect transistors (FETs), memristors and electrocatalysts for hydrogen evolution reaction (HER).

The rational design of efficient, low cost, and durable catalysts is critical for the industrial applications of electrocatalytic hydrogen production. A key step towards the structure design of high-performance catalysts for hydrogen evolution reaction (HER) relies on the in situ identification of the catalytic active sites in the process of HER, which is of great challenge. In this review, we summarize the recent advances on the in situ investigation of the active sites on low dimensional catalysts for HER. We highlight the characterization techniques used for this purpose, including scanning electrochemical microscopy (SECM), scanning electrochemical cell microscopy (SECCM), electrochemical scanning tunneling microscopy (EC-STM), in situ liquid phase transmission electron microscopy (LP-TEM), and in situ spectroscopic tools. We conclude with an overview of the main technical limitations for the current approaches and give an outlook to future opportunities in this emerging field.

Edge effects are predicted to significantly impact the properties of low dimensional materials with layered structures. The synthesis of low dimensional materials with copious edges is desired for exploring the effects of edges on the band structure and properties of these materials. Here we developed an approach for synthesizing MoS₂ nanobelts terminated with vertically aligned edges by sulfurizing hydrothermally synthesized MoO₃ nanobelts in the gas phase through a kinetically driven process; we then investigated the electrical and magnetic properties of these metastable materials. These edge-terminated MoS₂ nanobelts were found to be metallic and ferromagnetic, and thus dramatically different from the semiconducting and nonmagnetic two-dimensional (2D) and three-dimensional (3D) 2H-MoS₂ materials. The transitions in electrical and magnetic properties elucidate the fact that edges can tune the properties of low dimensional materials. The unique structure and properties of this one-dimensional (1D) MoS₂ material will enable its applications in electronics, spintronics, and catalysis.