Nanostructured photocatalysts and doped wide-bandgap semiconductors
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.
1. A catalyst for reduction of carbon dioxide and water comprising:
nanostructured titanium dioxide doped with one of: copper, wherein the nanostructured titanium dioxide forms a p-type semiconductor; nitrogen, wherein the nanostructured titanium dioxide forms a p-type semiconductor; niobium, copper indium sulfide nanoparticles having a diameter of 3 nm to 4.6 nm, wherein the copper indium sulfide nanoparticles are attached to a surface of the nanostructured titanium dioxide; molybdenum disulfide nanosheets, wherein the nanostructured titanium dioxide is in the form of nanotubes and the titanium dioxide nanotubes are coated by the molybdenum disulfide nanosheets; and cadmium sulfide nanoparticles having a diameter of about 3 nm to about 5 nm, wherein the nanostructured titanium dioxide is in the form of nanotubes and the titanium dioxide nanotubes are coated by the cadmium sulfide nanoparticles.
2. The catalyst of claim 1 , wherein the nanostructured titanium dioxide is in the form of nanoparticles.
3. The catalyst of claim 2 , wherein the titanium dioxide nanoparticles have a diameter of about 10 nm to about 15 nm.
4. The catalyst of claim 1 , wherein the nanostructured titanium dioxide is doped with the copper indium sulfide nanoparticles.
5. The catalyst of claim 4 , wherein a loading of copper indium sulfide is about 14% by weight.
6. The catalyst of claim 4 , wherein the nanostructured titanium dioxide is comprised by nanoparticles and about three quantum dots of copper indium sulfide are attached per titanium dioxide nanoparticle.
7. The catalyst of claim 1 , wherein the nanostructured titanium dioxide is in the form of nanotubes.
8. The catalyst of claim 7 , wherein the titanium dioxide nanotubes are doped with nitrogen.
9. The catalyst of claim 7 , wherein the titanium dioxide nanotubes are coated by the copper indium sulfide nanoparticles.
10. The catalyst of claim 7 , wherein the titanium dioxide nanotubes are coated by the molybdenum disulfide nanosheets.
11. The catalyst of claim 1 , wherein the molybdenum disulfide nanosheets are substantially two-dimensional nanostructures having a thickness from about 1 nm to about 100 nm.
12. The catalyst of claim 1 , wherein the nanostructured titanium dioxide is doped with at least about 5% by weight copper.
13. The catalyst of claim 1 , wherein the nanostructured titanium dioxide is doped with at least about 5% by weight nitrogen.
14. The catalyst of claim 1 , wherein the nanostructured titanium dioxide is doped with niobium.
15. The catalyst of claim 14 , wherein the nanostructured titanium dioxide is doped with at least about 10% by weight niobium.
16. The catalyst of claim 14 , wherein the nanostructured titanium dioxide forms an n-type semiconductor.
17. A catalyst for reduction of carbon dioxide and water comprising:
nanostructured cadmium sulfide, wherein at least a portion of a surface of the nanostructured cadmium sulfide is coated with zinc selenide.
18. The catalyst of claim 17 , wherein the nanostructured cadmium sulfide is comprised by nanorods.
19. The catalyst of claim 18 , wherein the nanorods have a length of at least about 20 nm.
20. The catalyst of claim 18 , wherein the cadmium sulfide nanorods have a quantum confined bandgap of about 2.68 eV and bandedge photoluminescence of about 2.62 eV.
21. The catalyst of claim 17 , wherein the nanostructured cadmium sulfide is comprised by nanoparticles.
22. The catalyst of claim 21 , wherein the cadmium sulfide nanoparticles have a diameter of about 3 nm to about 8 nm.
23. A catalyst for reduction of carbon dioxide and water comprising:
nanostructured cadmium sulfide, wherein the nanostructured cadmium sulfide is comprised by nanorods and the cadmium sulfide nanorods comprise a metal-hybrid.
24. The catalyst of claim 23 , wherein the metal comprises one of silver and gold.
25. The catalyst of claim 23 , wherein the metal-hybrid is grown at an end of the cadmium sulfide nanorods.
26. A catalyst for reduction of carbon dioxide and water comprising:
nanostructured titanium dioxide doped with copper, wherein the nanostructured titanium dioxide forms a p-type semiconductor.
27. A catalyst for reduction of carbon dioxide and water comprising:
nanostructured titanium dioxide doped with nitrogen, wherein the nanostructured titanium dioxide forms a p-type semiconductor.