Two-dimensional (2D) metallic transition metal dichalcogenides (MTMDs) have recently emerged as a new class of materials for the engineering of novel electronic phases, 2D superconductors, magnets, as well as novel electronic applications. However, the mechanical exfoliation route is predominantly used to obtain such metallic 2D flakes, the batch production remains challenging. Herein, we report the van der Waals epitaxial growth of monocrystalline, 1T-phase, few-layer metallic VSe2 nanosheets on an atomically flat mica substrate via a "one-step" chemical vapor deposition (CVD) method. The thickness of the VSe2 nanosheets is precisely tuned from several nanometers to several tenths nanometers. More significantly, the 2D VSe2 single crystals are found to present excellent metallic feature, as evidenced by an extra-high electrical conductivity of up to 106 S m-1, 1-4 orders of magnitude higher than that of various conductive 2D materials. The thickness-dependent CDW phase transitions are also examined through low-temperature transport measurements, which reveal that the synthesized 2D metallic 1T-VSe2 nanosheets should serve as good research platforms for the detecting novel many-body states. The present results open a new path for the synthesis and property investigations of nanoscale-thickness 2D MTMDs crystals.
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