Nanostructures having crystalline and amorphous phases

Abstract

The present invention includes a nanostructure, a method of making thereof, and a method of photocatalysis. In one embodiment, the nanostructure includes a crystalline phase and an amorphous phase in contact with the crystalline phase. Each of the crystalline and amorphous phases has at least one dimension on a nanometer scale. In another embodiment, the nanostructure includes a nanoparticle comprising a crystalline phase and an amorphous phase. The amorphous phase is in a selected amount. In another embodiment, the nanostructure includes crystalline titanium dioxide and amorphous titanium dioxide in contact with the crystalline titanium dioxide. Each of the crystalline and amorphous titanium dioxide has at least one dimension on a nanometer scale.

What is claimed is: 
     
         1 . A method of making a nanostructure comprising:
 providing a titanium dioxide (TiO 2 ) crystalline core; and   changing a portion of the TiO 2  crystalline core to a TiO 2  amorphous outer most shell in contact with and completely surrounding the crystalline core, wherein the TiO 2  amorphous outer most shell further comprises a hydrogen dopant and has a composition different than the TiO 2  crystalline core.   
     
     
         2 . The method of  claim 1  further comprising synthesizing the TiO 2  crystalline core. 
     
     
         3 . The method of  claim 2  wherein synthesizing the TiO 2  crystalline core comprises:
 providing a precursor; and 
 processing the precursor to produce the TiO 2  crystalline core. 
 
     
     
         4 . The method of  claim 3  wherein the precursor is selected from the group consisting of a gas, a liquid, a solution, a gel, and a solid. 
     
     
         5 . The method of  claim 3  wherein processing the precursor comprises a technique selected from the group consisting of a solution chemistry technique, a sol-gel technique, a hydrothermal technique, a solvothermal technique, a thermal technique, an electrochemistry technique, a chemical vapor deposition technique, and a physical vapor deposition technique. 
     
     
         6 . The method of  claim 3  wherein processing the precursor comprises producing crystalline nanoparticles that are arranged in an assembly of the crystalline nanoparticles. 
     
     
         7 . The method of  claim 3  wherein processing the precursor comprises depositing crystalline nanoparticles onto a substrate. 
     
     
         8 . The method of  claim 1  wherein changing the portion of the TiO 2  crystalline core to an amorphous phase comprises employing ions, atoms, or molecules to create disorder in a portion of the crystalline nanostructure. 
     
     
         9 . The method of  claim 1  wherein changing the portion of the TiO 2  crystalline core to an amorphous phase comprises a hydrogenation technique. 
     
     
         10 . The method of  claim 1  changing the portion of the TiO 2  crystalline core to an amorphous phase comprises an ion bombardment technique. 
     
     
         11 . The method of  claim 1  changing the portion of the TiO 2  crystalline core to an amorphous phase comprises exposing the crystalline nanostructure to a noble gas at elevated temperature and pressure. 
     
     
         12 . The method of  claim 11  wherein the noble gas is selected from the group consisting of helium, neon, argon, krypton, and xenon. 
     
     
         13 . A method of photocatalysis comprising:
 contacting a reactant fluid to a nanoparticle comprising a titanium dioxide (TiO 2 ) crystalline core, and a TiO 2  amorphous outer most shell in contact with and completely surrounding the crystalline core, wherein the TiO 2  amorphous outer most shell further comprises a hydrogen dopant and has a composition different than the TiO 2  crystalline core; and   exposing the nanostructure to light, thereby producing a reaction product from the reactant fluid.   
     
     
         14 . The method of  claim 13  wherein the light comprises sunlight. 
     
     
         15 . The method of  claim 13  wherein the light comprises simulated sunlight. 
     
     
         16 . The method of  claim 13  wherein the reactant fluid comprises an environmental contaminant, and exposing the nanostructure to the sunlight causes at least some of the environmental contaminant to decompose. 
     
     
         17 . The method of  claim 13  wherein, the fluid comprises water, and exposing the nanostructure to the sunlight causes decomposition of at least some of the water, thereby producing the reaction product of hydrogen. 
     
     
         18 . The method of  claim 17  wherein the reactant fluid comprises a solution of liquid water and a sacrificial agent. 
     
     
         19 . The method of  claim 18  wherein the sacrificial agent comprises an alcohol. 
     
     
         20 . The method of  claim 13  wherein the reactant fluid comprises a gas. 
     
     
         21 . The method of  claim 13  wherein the reactant fluid comprises a liquid. 
     
     
         22 . The method of  claim 22  further comprising contacting additional nanoparticles and the reactant fluid. 
     
     
         23 . The method of  claim 13  wherein the nanoparticles form a porous network of nanoparticles. 
     
     
         24 . The method of  claim 13  wherein the nanoparticle further comprises transition metal particles on a surface of the nanoparticle.