A method for preparing nanocrystal-metal oxide composites with long-term stability is disclosed herein. The nanocrystals are mixed with a first metal oxide precursor, a solvent and water to form a sol-gel composite. The sol-gel composite is pulverized to form a sol-gel composite powder. The sol-gel composite is then reacted with a second metal oxide precursor. The nanocrystal-metal oxide composites have a high luminescence efficiency and uniform emission wavelengths. The nanocrystal-metal oxide composite is used to manufacture a light-emitting device.

A method for preparing nanocrystal-metal oxide composites with long-term stability is disclosed herein. The nanocrystals are mixed with a first metal oxide precursor, a solvent and water to form a sol-gel composite. The sol-gel composite is pulverized to form a sol-gel composite powder. The sol-gel composite is then reacted with a second metal oxide precursor. The nanocrystal-metal oxide composites have a high luminescence efficiency and uniform emission wavelengths. The nanocrystal-metal oxide composite is used to manufacture a light-emitting device.

A method for synthesizing two-dimensional (2D) nanosheets comprises heating a bulk material in a solvent. The process is scalable and can be used to produce solution-processable 2D nanosheets with uniform properties in large volumes.

Methods of sulfurizing metal containing particles in the absence of hydrogen are described. One method includes contacting a bed of metal containing particles with a gaseous stream comprising hydrogen sulfide and inert gas under reaction conditions sufficient to produce sulfided metal containing particles. The gaseous stream is introduced into a vertical reactor at an inlet positioned at the bottom portion of the reactor and any unreacted hydrogen sulfide and inert gas is removed at an outlet positioned above the inlet. The sulfided metal containing particles can be removed from the reactor and stored.

Methods of sulfurizing metal containing particles in the absence of hydrogen are described. One method includes contacting a bed of metal containing particles with a gaseous stream comprising hydrogen sulfide and inert gas under reaction conditions sufficient to produce sulfided metal containing particles. The gaseous stream is introduced into a vertical reactor at an inlet positioned at the bottom portion of the reactor and any unreacted hydrogen sulfide and inert gas is removed at an outlet positioned above the inlet. The sulfided metal containing particles can be removed from the reactor and stored.

Provided is an internal hybrid electrochemical cell comprising: (A) a pseudocapacitance cathode comprising both graphene sheets and a 2D inorganic material, in a form of nanodiscs, nanoplatelets, or nanosheets that are bonded to or supported by primary surfaces (not the edges) of the graphene sheets and the 2D inorganic material and graphene sheets form a redox pair for pseudocapacitance; (B) a battery-like anode comprising a prelithiated anode active material (e.g. prelithiated Si, SiO, Sn, SnO.sub.2, etc.), and (C) a lithium-containing electrolyte in physical contact with the anode and the cathode; wherein the cathode active material has a specific surface area no less than 100 m.sup.2/g which is in direct physical contact with the electrolyte.

According to one embodiment, nano metal compound particles are provided. The nano metal compound particles have an average particle size of 50 nm or less. The nano metal compound particles have a peak ?.sub.t of 2.8 eV or less. The peak ?.sub.t corresponds to a resonant frequency of an oscillator according to a spectroscopic ellipsometry method fitted to a Lorentz model.

According to one embodiment, nano metal compound particles are provided. The nano metal compound particles have an average particle size of 50 nm or less. The nano metal compound particles have a peak ?.sub.t of 2.8 eV or less. The peak ?.sub.t corresponds to a resonant frequency of an oscillator according to a spectroscopic ellipsometry method fitted to a Lorentz model.

The present invention relates to a method of producing metal nanoparticles and metal sulfide nanoparticles using a recombinant microorganism co-expressing metallothionein and phytochelatin synthase, which are heavy metal-adsorbing proteins, and to the use of metal nanoparticles and metal sulfide nanoparticles synthesized by the method. The present invention provides a method for synthesizing metal nanoparticles which have been difficult to synthesize by conventional biological methods. The present invention makes it possible to synthesize metal nanoparticles in an environmentally friendly and cost-effective manner, and also makes it possible to synthesize metal sulfide nanoparticles. In addition, even metal nanoparticles which could have been produced by conventional chemical or biological methods are produced in a significantly increased yield by use of the method of the present invention.

A method for production of phosphate compounds comprises dissolving of a raw material comprising phosphorus, aluminium and iron, in a mineral acid. Insoluble residues from the dissolving step are separated. Iron hydroxide is added causing precipitation of phosphate compounds. The precipitated phosphate compounds are removed. The phosphate compounds are dissolved by an alkaline solution. Iron hydroxide is filtered out. Lime is added, causing precipitation of calcium phosphate. The precipitated calcium phosphate is separated. The leach solution after the separating of precipitated calcium phosphate is recycled to be used for dissolving phosphate compounds by an alkaline solution.