NANOSTRUCTURED PHOTOCATALYSTS AND DOPED WIDE-BANDGAP SEMICONDUCTORS

• US 20180117577A1
• Filed: 11/30/2017
• Published: 05/03/2018
• Est. Priority Date: 07/01/2013
• Status: Active Grant

• Current Assignee: The Board of Regents of the University of Colorado (University of Colorado System)
• Original Assignee: The Board of Regents of the University of Colorado (University of Colorado System)
• Inventors: Nagpal, Prashant, Singh, Vivek, Castellanos Beltran, Ignacio, Alivov, Yahya, Ding, Yuchen, Cerkovnik, Logan Jerome
• Granted Patent: US 10,449,530 B2
• Time in Patent Office: Days
• CPC Class Codes: B01J 23/72 Copper
• CPC Class Codes: B01J 27/04 Sulfides
• CPC Class Codes: B01J 27/047 with chromium, molybdenum, tungsten or polonium
• CPC Class Codes: B01J 27/051 Molybdenum
• CPC Class Codes: B01J 27/0573 Selenium; Compounds thereof
• CPC Class Codes: B01J 35/23 in a colloidal state
• CPC Class Codes: B01J 35/39 Photocatalytic properties
• CPC Class Codes: B01J 35/40 characterised by dimensions, e.g. grain size in a colloidal state B01J35/23; crystallite size B01J35/77
• CPC Class Codes: C01G 11/02 Sulfides
• CPC Class Codes: C01P 2004/16 Nanowires or nanorods, i.e. solid nanofibres with two nearly equal dimensions between 1-100 nanometer
• CPC Class Codes: C01P 2004/51 Particles with a specific particle size distribution
• CPC Class Codes: C25B 1/04 by electrolysis of water
• CPC Class Codes: C25B 11/091 consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds
• CPC Class Codes: C25B 3/25 Reduction
• CPC Class Codes: Y02E 60/36 Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
• CPC Class Codes: Y02P 20/133 Renewable energy sources, e.g. sunlight

Abstract

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.

Claims

1. A composition comprising uniformly doped wide-bandgap semiconductor nanotubes.

2. The composition of claim 1, wherein the uniformly doped wide-bandgap semiconductor nanotubes lack secondary phase diffraction peaks when subjected to energy dispersive x-ray spectroscopy.

3. The composition of claim 1, wherein the dopant is anionic.

4. The composition of claim 1, wherein the dopant is cationic.

5. The composition of claim 1, wherein the nanotubes are mono-doped.

6. The composition of claim 1, wherein the nanotubes are co-doped.

7. The composition of claim 1, wherein the nanotubes comprise titanium dioxide.

8. The composition of claim 1, wherein the nanotubes comprise tungsten oxide.

9. The composition of claim 1, wherein the nanotubes are n-type doped wide-bandgap semiconductor nanotubes.

10. The composition of claim 1, wherein the nanotubes are p-type doped wide-bandgap semiconductor nanotubes.

11. The composition of claim 1, wherein the nanotubes are doped with one of copper, copper-nitrogen, nitrogen, niobium-nitrogen, iron, and niobium.

12. The composition of claim 1, wherein the nanotubes are doped with one of:

copper, wherein the nanotubes form a p-type semiconductor;

nitrogen, wherein the nanotubes form 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 nanotubes;

molybdenum disulfide nanosheets, wherein the nanotubes are coated by the molybdenum disulfide nanosheets; and

cadmium sulfide nanoparticles having a diameter of about 3 nm to about 5 nm.

13. The composition of claim 1, wherein the nanotubes comprise about 0.1% by weight of dopant to about 10% by weight of dopant.

14. The composition of claim 1, wherein the nanotubes comprise about 1% by weight of dopant.

15. A device comprising the composition of claim 1.

16. The device of claim 15, wherein the device is one of a photovoltaic device, a display device, a photocatalytic device, an optoelectronic device, a light emitting diode, a thermoelectric device, and a spintronic device.

17. A method of making uniformly doped wide-bandgap semiconductor nanotubes comprising:

growing nanotubes by electrochemical oxidation using an electrochemical cell, the electrochemical cell including a first portion having a first electrode and a second portion having a second electrode, the first portion and the second portion separated by a porous membrane, the first portion including an electrolyte free of dopant, the second portion including an electrolyte having a dopant precursor; and

doping the nantotubes during the growing step to make uniformly doped wide-bandgap semiconductor nanotubes.

18. The method of claim 17, wherein the first electrode and the second electrode are coupled to an alternating current voltage source.

19. The method of claim 18, wherein alternating current voltage source applies rectangular shaped power pulses.

20. The method of claim 17, wherein the first electrode comprises platinum.

21. The method of claim 17, wherein the second electrode comprises titanium.

22. The method of claim 17, wherein growing nanotubes by electrochemical oxidation includes changing one of an anode voltage and a growth time to tune one of a diameter, a thickness, and a length of the nanotubes.

23. The method of claim 17, wherein doping the nanotubes to make doped wide-bandgap semiconductor nanotubes includes changing an amount of dopant to proportionally change a conductivity of the nanotubes.

24. The method of claim 17, wherein doping the nanotubes to make doped wide-bandgap semiconductor nanotubes includes incorporating shallow niobium donors to make highly transparent oxide nanotubes.

25. The method of claim 17, wherein doping the nanotubes to make doped wide-bandgap semiconductor nanotubes includes co-doping the nanotubes to increase absorption of infrared light by the nanotubes.

26. The method of claim 17, wherein doping the nanotubes to make doped wide-bandgap semiconductor nanotubes includes changing the magnetic properties of the nanotubes.

27. The method of claim 17, wherein doping the nanotubes to make doped wide-bandgap semiconductor nanotubes includes changing an amount of dopant precursor to control an amount of doping.