The present invention discloses a process for the preparation of metal sulphide quantum dots by using a very low cost sulphur precursor as a sulphur source. The metal sulphide quantum dots finds application in optical devices selected from photovoltaic cells, photodetectors and light-emission devices.

The present invention discloses a process for the preparation of metal sulphide quantum dots by using a very low cost sulphur precursor as a sulphur source. The metal sulphide quantum dots finds application in optical devices selected from photovoltaic cells, photodetectors and light-emission devices.

This present disclosure provides a core-shell quantum dot, a preparation method thereof, and a light-emitting device containing the same. The core of the core-shell quantum dot is CdSe.sub.XS.sub.(1-X), and the quantum dot shells include a first shell and a second shell, the first shell being selected from one or more of ZnSe, ZnSe.sub.YS.sub.(1-Y) and Cd.sub.(Z)Zn.sub.(1-Z)S, the second shell covering the first shell being one of Cd.sub.(Z)Zn.sub.(1-Z)S and ZnS, the maximum emission peak of the core-shell quantum dot is less than or equal to 480 nm, 0<X<1, 0<Y<1, 0<Z<1. The CdSe.sub.XS.sub.(1-X) core has a smaller bandgap and a shallower HOMO energy level, making hole injection easier.

The present invention provides a composition of porous mineral nucleus and a shell, wherein the porous mineral nucleus has a porous surface and the shell includes a material selected from the group of: a metal, an organic molecule, or a combination thereof.

Photocatalysts for reduction of carbon dioxide and water are provided that can be tuned to produce certain reaction products, including hydrogen, alcohol, aldehyde, and/or hydrocarbon products. These photocatalysts can form artificial photosystems and can be incorporated into devices that reduce carbon dioxide and water for production of various fuels. Doped wide-bandgap semiconductor nanotubes are provided along with synthesis methods. A variety of optical, electronic and magnetic dopants (substitutional and interstitial, energetically shallow and deep) are incorporated into hollow nanotubes, ranging from a few dopants to heavily-doped semiconductors. The resulting wide-bandgap nanotubes, with desired electronic (p- or n-doped), optical (ultraviolet bandgap to infrared absorption in co-doped nanotubes), and magnetic (from paramagnetic to ferromagnetic) properties, can be used in photovoltaics, display technologies, photocatalysis, and spintronic applications.

Photocatalysts for reduction of carbon dioxide and water are provided that can be tuned to produce certain reaction products, including hydrogen, alcohol, aldehyde, and/or hydrocarbon products. These photocatalysts can form artificial photosystems and can be incorporated into devices that reduce carbon dioxide and water for production of various fuels. Doped wide-bandgap semiconductor nanotubes are provided along with synthesis methods. A variety of optical, electronic and magnetic dopants (substitutional and interstitial, energetically shallow and deep) are incorporated into hollow nanotubes, ranging from a few dopants to heavily-doped semiconductors. The resulting wide-bandgap nanotubes, with desired electronic (p- or n-doped), optical (ultraviolet bandgap to infrared absorption in co-doped nanotubes), and magnetic (from paramagnetic to ferromagnetic) properties, can be used in photovoltaics, display technologies, photocatalysis, and spintronic applications.

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 process for preparing alloy products is described using a self-sustaining or self-propagating SHS-type combustion process with point-source ignition, preferably a laser, in a pressurized vessel. Binary, ternary and quaternary alloys can be formed with control over polycrystalline structure and bandgap. Methods to tune the bandgap and the alloys formed are described. The alloy products may be doped. Preferably sulfides, tellurides or selenides are formed. Cooling during reaction takes place.

The presently disclosed subject matter provides processes for preparing nanocrystals, including processes for preparing core-shell nanocrystals. The presently disclosed subject matter also provides sulfur and selenium compounds as precursors to nanostructured materials. The presently disclosed subject matter also provides nanocrystals having a particular particle size distribution.