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Tungsten Disulfide (WS2) films, as one of the most attractive members in the family of transition metal dichalcogenides, were synthesized typically on SiO2/Si sub-strate by confine-spaced chemical vapor deposition (CVD) method. The whole pro-cess could be controlled efficiently by precursor concentration and fast thermal pro-cess. To be priority, the effect of fast heating-up to cooling-down process and source ratio-dependent rule for WS2 structure have been systematically studied, leading to high-yield and fine structure of monolayer WS2 films with standard triangular mor-phology and average edge length of 92.4 μm. The growth time of the samples was regulated within 3 minutes, and the optimal source ratio of sulfur to tungsten oxide is about 200:3. The whole experimental duration was about 50 minutes, which is only about quarter in comparison to relevant reports. We assume one type of "multi-nucleation dynamic process" to provide a potential way for fast synthesis of the sam-ples. Finally, the good performance of as-fabricated field-effect transistor (FET) on WS2 film was achieved, which exhibits high electron mobility of 4.62 cm2V−1s−1, fast response rate of 42 ms, and remarkable photoresponsivity of 3.7×10-3A/W. Our work will provide a promising robust way for rapid synthesis of high-quality monolayer TMDs films and pave the way for the potential applications of TMDCs.

Transition metal dichalogenides (TMDCs) with unique layered structures hold promising potential as transducers for photothermal therapy. However, the low photothermal conversion efficiency and poor stability in some cases limit their practical applications. Herein, we demonstrate the fabrication of ultrathin homogeneous hybridized TMDC nanosheets and their use for highly efficient photothermal tumor ablation. In particular, the nanosheets were composed of metallic WSe2 intercalated with polyvinylpyrrolidone (PVP), which was facilely prepared through a solvothermal process from the mixture of selenourea crystals, WCl6 powder along with PVP polymeric nanogel. Our characterizations revealed that the obtained nanosheets exhibited excellent photothermal conversion efficiency, therapeutic demonstration with improved biocompatibility and physiological stability attributing to the combined merits of metallic phase of WSe2 and hydrophilic PVP insertion. Both the histological analysis of vital organs and in vitro/in vivo tests confirmed the nanosheets as actively effective and biologically safe in this phototherapeutic technique. Findings from this non-invasive experiment clearly emphasize the explorable therapeutic efficacy of the layered-based hybrid agents in future cancer treatment planning procedures.

The electronic performance of graphene is largely related to its morphology, surface, size and various synthesis conditions, mainly because of the presence of grain boundary. Better understanding on the relationship between the size and electronic property is very important for graphene's applications in potential electronics. Herein, we selectively synthesized single-crystal graphene using a chemical vapor deposition (CVD) method. The obtained CVD-graphene exhibited various sizes, ranging from 20 μm to 120 μm. Our measurements of field effect transistor devices revealed that the charge carrier mobility of CVD-graphene could increase from 17.8 to 720 cm 2 V −1 s −1 with the size decreasing. The better electronic performance in comparable smaller-size graphene was ascribed to less grain boundary compared with the bigger one, which was further confirmed by our observations from scanning tunneling microscope/spectroscopy (STM/STS).

Two dimensional (2D) single crystal layered transition materials have had extensive consideration owing to their interesting magnetic properties, originating from their lattices and strong spin-orbit coupling, which make them of vital importance for spintronic applications. Herein, we present synthesis of a highly crystalline tungsten diselenide layered single crystal grown by chemical vapor transport technique and doped with nickel (Ni) to tailor its magnetic properties. The pristine WSe2 single crystal and Ni-doped crystal were characterized and analyzed for magnetic properties using both experimental and computational aspects. It was found that the magnetic behavior of the 2D layered WSe2 crystal changed from diamagnetic to ferromagnetic after Ni-doping at all tested temperatures. Moreover, first principle density functional theory (DFT) calculations further confirmed the origin of room temperature ferromagnetism of Ni-doped WSe2, where the d-orbitals of the doped Ni atom promoted the spin moment and thus largely contributed to the magnetism change in the 2D layered material.