2D materials have attracted much attention because of frontier electronic materials due to its superior electronic transport properties and mechanical flexibility in the future, making it a potential material for high performance and wearable electronics. Graphene is a typical 2D materials with high carrier mobility; however, it still cannot be applied in transistor due to the lack of bandgap. A new type of 2D semiconducting materials called transition metal dichalcogenides (TMDCs), which are layered structure with the strong in-plane bonding and weak out-of-plane interactions similar to graphite, have been intensively studied. Recent studies have predicted exceptional physical properties upon reduced dimensionality attracting lots of attention due to the versatile physical chemical behaviors. Nevertheless, the synthesis and the study of the fundamental physical properties of TMDs are still in early stages. The lack of a large-area and reliable synthesis method restrict exploring all the potential applications of the TMDs. Chemical vapor deposition (CVD) is a traditional approach for the growth of TMDs; nevertheless, the high growth temperature is a major drawback for its to be applied in flexible electronics. In this talk, an inductively coupled plasma (ICP) was used to synthesize Transition Metal Dichalcogenides (TMDs) through a plasma-assisted selenization process of metal oxide (MO_x) at a low temperature, as low as 250 °C. Compared to other CVD processes the use of ICP facilitates the decomposition of the precursors at lower temperatures; therefore, the temperature required for the formation of TMDs can be drastically reduced. WSe₂ was chosen as a model material system due to its technological importance as a p-type inorganic semiconductor with an excellent hole mobility. Large-area synthesis of WSe₂ on polyimide (30 x 40 cm²) flexible substrates and 8-inch silicon wafers with good uniformity was demonstrated at the formation temperature of 250 °C as confirmed by Raman and X-ray Photoelectron (XPS) spectroscopy.  Furthermore, by controlling different H₂/N₂ ratios, hybrid WO_x/WSe₂ films can be formed at the formation temperature of 250 ºC as shown by TEM and confirmed by XPS. In addition, the plasma-engineered-1T/2H 3D-hierarchical WSe₂/MoSe₂ nanoscrews derived from the WOx/MoOxD-hierarchical nanoscrews through a low-temperature plasma-assisted selenization process with controlled shapes grown by a glancing angle deposition system (GLAD). The applications including (1) water splitting, (2) gas sensors, (3) photodetectors, (3) anode materials in secondary ion battery will be reported in this talk.