Disclosed herein is a method of producing a substrate having a wrinkle pattern of a single-layer rhenium disulfide (ReS.sub.2) nanoflakes deposited thereon. The method is characterized by using ammonium rhenium and sulfur powders as the rhenium source and the sulfur source, respectively; and with the addition of molecular sieve to control the release of the rhenium source during the deposition of ReS.sub.2, in which a single layer of ReS.sub.2 is deposited on a substrate via chemical vapor deposition. The single-layer ReS.sub.2 is then exposed to UV light to induce the formation of a wrinkle pattern.

Disclosed herein is a method of producing a substrate having a wrinkle pattern of a single-layer rhenium disulfide (ReS.sub.2) nanoflakes deposited thereon. The method is characterized by using ammonium rhenium and sulfur powders as the rhenium source and the sulfur source, respectively; and with the addition of molecular sieve to control the release of the rhenium source during the deposition of ReS.sub.2, in which a single layer of ReS.sub.2 is deposited on a substrate via chemical vapor deposition. The single-layer ReS.sub.2 is then exposed to UV light to induce the formation of a wrinkle pattern.

Provided is a method of manufacturing MoS.sub.2 having a 1T crystal structure. The method includes performing phase transition from a 2H crystal structure of MoS.sub.2 to the 1T crystal structure by reacting MoS.sub.2 having the 2H crystal structure with CO gas. The phase transition includes annealing the MoS.sub.2 having the 2H crystal structure in an atmosphere including CO gas.

Provided is a method of manufacturing MoS.sub.2 having a 1T crystal structure. The method includes performing phase transition from a 2H crystal structure of MoS.sub.2 to the 1T crystal structure by reacting MoS.sub.2 having the 2H crystal structure with CO gas. The phase transition includes annealing the MoS.sub.2 having the 2H crystal structure in an atmosphere including CO gas.

The present disclosure relates to P-type SnSe crystal capable of being used as thermoelectric refrigeration material and a preparation method thereof. The material is a Na-doped and Pb-alloyed SnSe crystal. A molar ratio of Sn, Se, Pb and Na is (1-x-y):1:y:x, where 0.015≤x≤0.025 and 0.05≤y≤0.11. The P-type SnSe crystal provided by the present disclosure is capable of being used as the thermoelectric refrigeration material. A power factor PF of the P-type SnSe crystal at a room temperature is ≥70 μWcm.sup.−1K.sup.−2, and ZT at the room temperature is ≥1.2. A single-leg temperature difference measurement platform built on the basis of the obtained SnSe crystal may realize a refrigeration temperature difference of 17.6 K at a current of 2 A. The present disclosure adopts a modified directional solidification method and uses a continuous temperature region for slow cooling to grow a crystal to obtain the large-sized high-quality SnSe crystal.

The present disclosure relates to P-type SnSe crystal capable of being used as thermoelectric refrigeration material and a preparation method thereof. The material is a Na-doped and Pb-alloyed SnSe crystal. A molar ratio of Sn, Se, Pb and Na is (1-x-y):1:y:x, where 0.015≤x≤0.025 and 0.05≤y≤0.11. The P-type SnSe crystal provided by the present disclosure is capable of being used as the thermoelectric refrigeration material. A power factor PF of the P-type SnSe crystal at a room temperature is ≥70 μWcm.sup.−1K.sup.−2, and ZT at the room temperature is ≥1.2. A single-leg temperature difference measurement platform built on the basis of the obtained SnSe crystal may realize a refrigeration temperature difference of 17.6 K at a current of 2 A. The present disclosure adopts a modified directional solidification method and uses a continuous temperature region for slow cooling to grow a crystal to obtain the large-sized high-quality SnSe crystal.

A method of producing transition-metal dichalcogenide crystals includes providing a silicon substrate having a phosphine-treated surface, exposing the phosphine-treated surface of the silicon substrate to a vapor containing a transition metal, and exposing the phosphine-treated surface of the silicon substrate to a vapor containing a chalcogen. A crystal of the transition-metal and the chalcogen is formed on the phosphine-treated surface of the silicon substrate to produce a transition-metal dichalcogenide crystal by chemical vapor deposition.

The present disclosure relates to a graphene composite and a method of manufacturing the same, and a graphene composite according to an exemplary embodiment includes: a substrate; a first thin film positioned on the substrate; and a second thin film positioned on the first thin film, in which the first thin film includes graphene, and the second thin film includes at least any one of VSe.sub.2, VS.sub.2, VTe.sub.2, TaS.sub.2, TaSe.sub.2, NbS.sub.2, NbSe.sub.2, TiS.sub.2, TiSe.sub.2, TiTe.sub.2, ReS.sub.2, and ReSe.sub.2.

The present disclosure relates to a graphene composite and a method of manufacturing the same, and a graphene composite according to an exemplary embodiment includes: a substrate; a first thin film positioned on the substrate; and a second thin film positioned on the first thin film, in which the first thin film includes graphene, and the second thin film includes at least any one of VSe.sub.2, VS.sub.2, VTe.sub.2, TaS.sub.2, TaSe.sub.2, NbS.sub.2, NbSe.sub.2, TiS.sub.2, TiSe.sub.2, TiTe.sub.2, ReS.sub.2, and ReSe.sub.2.

Filled carbon nanotubes (CNTs) and methods of synthesizing the same are provided. An in situ chemical vapor deposition technique can be used to synthesize CNTs filled with metal sulfide nanowires. The CNTs can be completely and continuously filled with the metal sulfide fillers up to several micrometers in length. The filled CNTs can be easily collected from the substrates used for synthesis using a simple ultrasonication method.