Method of making Co3O4 nanorods for electrocatalytic water splitting

Patent metadata

Field	Value
Publication number	US-10533258-B2
Application number	US-201816001579-A
Country	US
Kind code	B2
Filing date	Jun 6, 2018
Priority date	Jun 6, 2018
Publication date	Jan 14, 2020
Grant date	Jan 14, 2020

Abstract

A method of making Co 3 O 4 nanorods by thermal decomposition of a cobalt salt is described. A method of using Co 3 O 4 nanorods as an electrocatalyst component to a porous carbon electrode is also described. The carbon electrode may be made of carbonized filter paper. Together, this carbon-supported Co 3 O 4 electrode may be used for water electrolysis.

First claim

The invention claimed is:

1. A method for making Co 3 O 4 nanorods, the method comprising:
heating at least one of Co(NO 3 ) 2 and Co(NO 3 ) 2 ·6H 2 O in air for 1-6 h at a temperature of 420-700° C. to produce Co 3 O 4 nanorods by thermal decomposition,
wherein the Co 3 O 4 nanorods have an average diameter of 10-70 nm and an average length of 20-100 nm.

2. The method of claim 1 , wherein the cobalt of the cobalt salt consists essentially of cobalt having a +2 oxidation state.

3. The method of claim 1 , wherein the Co 3 O 4 nanorods have an average aspect ratio of 1.05:1-3.0:1.

4. The method of claim 1 , wherein the Co 3 O 4 nanorods have a crystalline morphology.

5. The method of claim 1 , wherein at least 70% of the Co 3 O 4 nanorods have an average diameter of 25-60 nm.

6. The method of claim 1 , wherein the cobalt salt is Co(NO 3 ) 2 .6H 2 O.

7. A carbon-supported Co 3 O 4 electrode, comprising:
carbonized paper and
Co 3 O 4 nanorods having an average diameter of 10-70 nm and an average length of 20-100 nm, deposited on the carbonized paper,
wherein the carbon-supported Co 3 O 4 electrode is substantially free of Co 0 .

8. The carbon-supported Co 3 O 4 electrode of claim 7 , wherein the Co 3 O 4 nanorods consist essentially of Co 3 O 4 .

9. The carbon-supported Co 3 O 4 electrode of claim 7 , wherein a surface density of the Co 3 O 4 nanorods on the carbonized paper is 100-200 μg/cm 2 .

10. The carbon-supported Co 3 O 4 electrode of claim 7 , wherein the Co 3 O 4 nanorods are aggregated into clusters having diameters of 1-20 μm.

11. The carbon-supported Co 3 O 4 electrode of claim 10 , wherein the clusters have a nearest neighbor distance of 500 nm-20 μm.

12. The carbon-supported Co 3 O 4 electrode of claim 7 , wherein the Co 3 O 4 nanorods are made by heating a cobalt salt in air for 1-6 h at a temperature of 420-700° C. to produce Co 3 O 4 nanorods by thermal decomposition.

13. The carbon-supported Co 3 O 4 electrode of claim 7 , wherein the carbonized paper is made by heating a paper at 700-950° C. for 1-12 h in an inert atmosphere.

14. The carbon-supported Co 3 O 4 electrode of claim 7 , wherein the paper is a filter paper.

15. An electrochemical cell, comprising:
the carbon-supported Co 3 O 4 electrode of claim 10 ;
a counter electrode; and
an electrolyte solution in contact with both electrodes.

16. The electrochemical cell of claim 15 , further comprising a reference electrode in contact with the electrolyte solution.

17. The electrochemical cell of claim 15 , wherein the electrolyte solution comprises water and an inorganic base at a concentration of 0.05-0.4 M.

18. The electrochemical cell of claim 17 , wherein the carbon-supported Co 3 O 4 electrode has a current density of 30-45 mA/cm 2 when the electrodes are subjected to a potential of 1.3-1.8 V.

19. A method for decomposing water into H 2 and O 2 , the method comprising:
subjecting the electrodes of the electrochemical cell of claim 17 with a potential of 0.5-2.0 V.

20. The method of claim 19 , further comprising separately collecting H 2 -enriched gas and O 2 -enriched gas.

Assignees

• Univ King Fahd Pet & Minerals

Inventors

• Aziz Md Abdul
• Qasem Mohammed Ameen Ahmed

Classifications

• C01P2002/85

  by XPS, EDX or EDAX data · CPC title

• C01P2002/72

  by d-values or two theta-values, e.g. as X-ray diagram · CPC title

• Y10S977/762

  Nanowire or quantum wire, i.e. axially elongated structure having two dimensions of 100 nm or less · CPC title

• C01P2004/16

  Nanowires or nanorods, i.e. solid nanofibres with two nearly equal dimensions between 1-100 nanometer · CPC title

• C01P2004/04

  obtained by TEM, STEM, STM or AFM · CPC title