Method for synthesising a nano-product

• US 8,840,863 B2
• Filed: 08/28/2009
• Issued: 09/23/2014
• Est. Priority Date: 09/04/2008
• Status: Active Grant

• Current Assignee: Hong Kong University of Science and Technology
• Original Assignee: Hong Kong University of Science and Technology
• Inventors: Yang, Shihe, Liu, Chenmin
• Primary Examiner(s): Zimmer, Anthony J
• Application Number:
  US12/549,968
• Publication Number:
  US 20100069229A1
• Time in Patent Office: 1,852 Days
• Field of Search: 423608-610, 977/700, 977/762, 977/765, 977/766, 977/773, 977/775, 977/776
• US Class Current: 423/592.1
• CPC Class Codes: B01J 21/06 Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 21/063 Titanium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 27/14 Phosphorus; Compounds thereof
• CPC Class Codes: B01J 27/24 Nitrogen compounds
• CPC Class Codes: B01J 35/23 in a colloidal state
• CPC Class Codes: B01J 35/39 Photocatalytic properties
• CPC Class Codes: B01J 37/10 in the presence of water, e.g. steam
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01B 13/36 by precipitation reactions in aqueous solutions C01B13/328 takes precedence
• CPC Class Codes: C01G 23/047 Titanium dioxide
• CPC Class Codes: C01P 2002/52 containing elements as dopants
• CPC Class Codes: C01P 2002/84 by UV- or VIS- data
• CPC Class Codes: C01P 2004/04 obtained by TEM, STEM, STM or AFM
• 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 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: Y10S 977/70 Nanostructure
• CPC Class Codes: Y10S 977/762 Nanowire or quantum wire, i.e. axially elongated structure having two dimensions of 100 nm or less

Abstract

A method for the synthesis of nano-products, such as atomic titanium oxide wires. The method allows wires of anatase titanium oxide wires to be formed in a range of tunable diameters and aspect ratios in the nanometer and subnanometer size scales. The method also allows the titanium wires to be capped by oleic acid to enhance dispersing and solubility. The method allows the titanium wires to be surface doped with nitrogen species to enhance stability and functionality such as enhanced absorption in the visible wavelength region, which is useful for photodegradation of organic wastes in water by sunlight.

Claims

1. A method of synthesising a nano-product comprising the steps of:

a) providing a mixture of an M-alkoxide a first unsaturated carboxylic acid;

b) heating the mixture for a pre-determined period of time to form an M-complex precursor, wherein the heating comprises solvothermally treating the mixture in a sealed autoclave; and

c) subsequent to the step of forming the M-complex precursor, precipitating a nano-product of M-oxide from the M-complex precursor in the presence of a second mixture comprising at least each of a long chain unsaturated carboxylic acid, a nitrogen containing compound, and an organic compound,

wherein M is an element, the oxide of which is suitable to form a nano-product, and the M-complex precursor is an ester complex.

2. A method of synthesising a nano-product as claimed in claim 1 wherein precipitating a nano-product of M-oxide from the M-complex precursor in step c) comprises:

heating the M-complex precursor at a pre-determined temperature for a pre-determined period of time by heating the precursor to a predetermined temperature for a predetermined time such that 180°

C. renders an average diameter of 0.5 nm and heating the precursor to 300°

C. renders a mean diameter of about 3 nm, wherein the higher the temperature, the greater the diameter of the nano-product, and increasing the time of heating the M-complex precursor to increase the lengths of the nano-product.

3. A method of synthesising a nano-product as claimed in claim 2, further comprising selecting the first unsaturated carboxylic acid such that the M-complex precursor is non-volatile at the temperature in which the M-complex precursor is heated.

4. A method of producing a nano-product as claimed in claim 1 wherein the weight ratio of the second carboxylic acid to the M-alkoxide is in the range between 100:

3 and 1;

1.

5. A method of synthesising a nano-product as claimed in claim 1 wherein the second carboxylic acid is oleic acid, whereby a linear nano-product is obtained.

6. A method of synthesising a nano-product as claimed in claim 1 wherein the nano-product is precipitated from the M-complex precursor in the presence of an unsaturated amine, whereby the nano-product is nitrogen-doped.

7. A method of producing a nano-product as claimed in claim 6 wherein:

the weight ratio of the second carboxylic acid to the unsaturated amine during the precipitation of the nano-product is in the range between 1;

1 and 1;

2.

8. A method of synthesising a nano-product as claimed in claim 1 wherein the nano-product is precipitated from the M-complex precursor in the presence of a phosphorous containing dopant, whereby the nano-product is phosphorous-doped.

9. A method of synthesising a nano-product as claimed in claim 1 wherein the M-alkoxide is titanium alkoxide.

10. A method of synthesising a nano-product as claimed in claim 1 wherein the M-alkoxide is zirconium alkoxide.

11. A method of producing an atomic wire comprising the steps of claim 1, and further comprising the steps of precipitating M oxide to form atomic wires in the presence of a dopant, wherein the dopant forms a surface doping of the produced atomic wire.

12. A method of producing an atomic wire as claimed in claim 11 wherein the dopant is nitrogen provided by a nitrogen-containing organic compound such as organic amine.

13. A method of producing an atomic wire as claimed in claim 11 wherein the dopant is phosphorus provided by a phosphorus-containing organic compound.

14. A method of synthesising a nano-product comprising the steps of:

a) providing a mixture of an M-alkoxide and an unsaturated carboxylic acid;

b) heating the mixture for a pre-determined period of time to form an M-complex precursor in a sealed autoclave; and

c) precipitating a nano-product of M-oxide from the M-complex precursor in the presence of a second unsaturated carboxylic acid, wherein M is an element, the oxide of which is suitable to form a nano-product, and the M-complex precursor is an ester complex, wherein the second carboxylic acid is stearic acid, whereby a branched nano-product is obtained.

15. A method of synthesising a nano-product as claimed in claim 14 wherein precipitating a nano-product of M-oxide from the M-complex precursor in step c) comprises:

heating the M-complex precursor at a pre-determined temperature for a pre-determined period of time by heating the precursor to a predetermined temperature for a predetermined time such that 180°

C. renders an average diameter of 0.5 nm and heating the precursor to 300°

C. renders a mean diameter of about 3 nm, wherein the higher the temperature, the greater the diameter of the nano-product; and

increasing the time of heating the M-complex precursor to increase the lengths of the nano-product.

16. A method of synthesising a nano-product comprising the steps of:

a) providing a mixture of an M-alkoxide and an unsaturated carboxylic acid;

b) heating the mixture for a pre-determined period of time to form an M-complex precursor, wherein the heating comprises solvothermally treating the mixture in a sealed autoclave; and

c) subsequent to the step of forming the M-complex precursor, precipitating a nano-product of M-oxide from the M-complex precursor in the presence of an unsaturated amine and in the presence of a second mixture comprising at least each of a long chain unsaturated acid, a nitrogen containing compound, and an organic compound, wherein M is an element, the oxide of which is suitable to form a nano-product, thereby producing a nitrogen-doped nano-product and the M-complex precursor is an ester complex.