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.

A preparation method of fluorocarbon-coated VSe.sub.2 composite (VSe.sub.2@CF) anode electrode material, including: weighting and dissolving an acetylacetone oxovanadium (VO(acac).sub.2) and a selenium dioxide in a solvent to prepare a first solution with a concentration of 0.5-2 mol/L, and stirring the first solution for 0.5 h to obtain a dark green solution; adding the dark green solution with an organic acid to obtain a second solution; transferring the second solution to a polytetrafluoroethylene-lined high-pressure hydrothermal reactor, and holding at a heat insulation temperature for 15-30 h to obtain a third solution; after the third solution is cooled, suction filtering the cooled third solution, and washing the filtered third solution repeatedly to obtain a precipitate; drying the precipitate to obtain a black powder; co-mixing a citric acid solution with the black powder, stirring, ball milling, and drying; and heating up, holding, and finally cooling naturally to room temperature under inert atmosphere.

The disclosure relates to a method for preparing a 3D sponge structured carbonitride coated VSe.sub.2 composite (3D-VSe.sub.2@CN), belonging to the technical fields of electrode materials and preparation of batteries. In the disclosure, carbon, nitrogen and VSe.sub.2 are composited by using NaCl as a template so as to construct a 3D sponge structured carbonitride coated VSe.sub.2 composite. The 3D sponge structure can increase the structure stability of the material in the cyclic process, and the carbocanitride can increase the electron conductivity and activity sites of the material, so as to allow easier diffusion of potassium ions. Meanwhile, the stable structure can cause the clustering of VSe.sub.2 all the time. Thus, the prepared composite has good and stable rate capability and cycle stability. The process method is simple, low in cost, environmental-friendly, and suitable for large-scale industrial production.

There is provided a multi-layered membrane comprising a top layer, a bottom layer, and a spacer layer; wherein said spacer layer is interposed between said top layer and said bottom layer; wherein said top layer, said bottom layer and said spacer layer are each independently composed of one or more selective layers, each selective layer comprising a 2D material; wherein said spacer layer comprises at least one channel for receiving a fluid; wherein said bottom layer comprises a hole with an area in the range of 1 μm.sup.2 to 1 mm.sup.2; and wherein said hole is capable of being in fluid communication with said at least one channels of said spacer layer.

There is also provided a method to synthesize the top layer of a multi-layered membrane as disclosed herein, methods for separating a plurality of ions or molecules in a fluid stream, a device comprising a multi-layered membrane as disclosed herein, and use of the method or the device as disclosed herein in osmotic power generation.

A topological material includes a lattice crystalline structure; and a material defect in the lattice crystalline structure that is treatable by hydrogen passivation that chemically mitigates an electronic charge associated with the material defect. The lattice crystalline structure includes dangling bonds in an atomic arrangement of the material defect of the lattice crystalline structure, and the hydrogen passivation may apply hydrogen to chemically passivate the dangling bonds of the material defect. The hydrogen passivation may be achieved by diffusing hydrogen into common materials of the lattice crystalline structure. The hydrogen passivation may chemically and/or electrostatically neutralize an electronic activity associated with the material defect.

Methods for making nanocomposites are provided. In an embodiment, such a method comprises combining a first type of nanostructure with a bulk material in water or an aqueous solution, the first type of nanostructure functionalized with a functional group capable of undergoing van der Waals interactions with the bulk material, whereby the first type of nanostructure induces exfoliation of the bulk material to provide a second, different type of nanostructure while inducing association between the first and second types of nanostructures to form the nanocomposite.

A method for making a transition metal dichalcogenide crystal having a chemical formula represented as MX.sub.2 is provided, wherein M represents a central transition metal element, and X represents a chalcogen element. The method includes providing a MX.sub.2 polycrystalline powder, a MX.sub.2 seed crystal, and a transport medium. The MX.sub.2 polycrystalline powder and the transport medium are placed in a first reaction chamber. The first reaction chamber and the MX.sub.2 seed crystal are placed in a second reaction chamber having a source end and a deposition end opposite to the source end. The first reaction chamber is placed at the source end, and the MX.sub.2 seed crystal is placed at the deposition end.

A semiconductor nanoparticle, a production method thereof, and an electroluminescent device including the same. The production method includes: combining a magnesium precursor and an additive with a chalcogen precursor in a reaction medium including an organic solvent and an organic ligand; heating the reaction medium to a reaction temperature; and reacting the magnesium precursor and the chalcogen precursor in the presence of the additive to form a magnesium chalcogenide, wherein the semiconductor nanoparticle comprises the magnesium chalcogenide, wherein the magnesium chalcogenide comprises magnesium; and selenium, sulfur, or a combination thereof, and wherein the additive includes a hydride compound including an alkali metal, calcium, barium, aluminum, or a combination thereof.

A product includes a solution comprising Ag.sub.2Se quantum dots in a solvent. The solution is colloidally stable for at least one week. A product includes a solid layer formed of Ag.sub.2Se quantum dots. The layer is at least 100 nm thick. The layer is physically characterized by a substantial absence of defects therein. A process includes forming a solution of Ag.sub.2Se quantum dots and adding at least acetonitrile to the solution. The process further includes separating the Ag.sub.2Se quantum dots from the solution and washing the Ag.sub.2Se quantum dots at least two times in a solution comprising at least acetonitrile. The process further includes redispersing the washed Ag.sub.2Se quantum dots in a nonpolar solvent to create a colloidal suspension.

In a method for producing nanoparticles of copper selenide, a flowable copper precursor is formed by combining a copper starting material and a ligand, and a flowable selenium precursor is formed by suspending a selenium starting material in a liquid. Then a flowable copper-selenium mixture including a lower-polarity solvent is formed by combining the flowable copper precursor and the flowable selenium precursor. The flowable copper-selenium mixture is conducted through at least one heating unit, and the nanoparticles of copper selenide are isolated in an oxygen-depleted environment. The isolation includes combining a solution containing the nanoparticles of copper selenide and a deoxygenated, higher-polarity solvent to precipitate the nanoparticles.