Microwave synthesis of cobalt tungstate for use as stable oxygen evolution catalyst

Patent metadata

Field	Value
Publication number	US-10040050-B2
Application number	US-201414528219-A
Country	US
Kind code	B2
Filing date	Oct 30, 2014
Priority date	Oct 30, 2014
Publication date	Aug 7, 2018
Grant date	Aug 7, 2018

Abstract

A process of forming an oxygen evolution catalyst includes the steps of: providing Co(NO3)4; providing Na2WO4; combining the Co(NO3)4 and Na2WO4 forming a solution; exposing the solution to a source of microwave energy and initiating a hydrothermal reaction forming hydrated CoWO4. The oxygen evolution catalyst including hydrated CoWO4 may be used to split water into oxygen and hydrogen ions.

First claim

Having described our invention, we claim:

1. An oxygen evolution catalyst splitting water into oxygen and hydrogen ions comprising hydrated Cobalt Tungstate having a hydrated pseudo crystalline phase of the formula: CoWO 4 xH 2 O wherein x is 1.2 to 1.7.

2. The oxygen evolution catalyst of claim 1 wherein the hydrated Cobalt Tungstate includes a plurality of nanoparticles having a size of from 1 to 10 nm.

3. The oxygen evolution catalyst of claim 1 further including conductive particles and a binder combined with nanoparticles of the hydrated Cobalt Tungstate.

4. The oxygen evolution catalyst of claim 1 wherein the catalyst has a surface area of from 40-110 m 2 /g.

5. The water oxidation catalyst of claim 1 wherein the catalyst maintains 100% of its activity following 20 charge cycles.

6. The water oxidation catalyst of claim 1 wherein the hydrated Cobalt Tungstate has a steady state activity greater than amorphous Cobalt Tungstate.

7. A process for oxidizing water, the process comprising:
providing hydrated Cobalt Tungstate having a hydrated pseudo crystalline phase of the formula: CoWO 4 xH 2 O wherein x is 1.2 to 1.7;
providing water; and
placing the water into contact with the hydrated Cobalt Tungstate, the hydrated Cobalt Tungstate catalyzing the oxidation of water.

8. The process of claim 7 , wherein the hydrated Cobalt Tungstate is a plurality of hydrated Cobalt Tungstate nanoparticles.

9. The process of claim 8 , further including applying an electrical potential between the hydrated Cobalt Tungstate and the water.

10. The process of claim 8 , further including adding a photo-sensitizer to the water and exposing the water with photo-sensitizer to electromagnetic radiation, the photo-sensitizer providing an electrical potential between the hydrated Cobalt Tungstate and the water.

11. The process of claim 10 , wherein the photo-sensitizer is a ruthenium-tris(2,2′-bipyridyl) compound.

12. A process for forming an oxygen evolution catalyst including the steps of:
providing Co(NO 2 ) 4 ;
providing Na 2 WO 4 ;
combining the Co(NO 3 ) 4 and Na 2 WO 4 forming a solution;
exposing the solution to a source of microwave energy and initiating a hydrothermal reaction forming hydrate CoWO 4 having a hydrated pseudo crystalline phase of the formula: CoWO 4 xH 2 O wherein x is 1.2 to 1.7.

13. The process of claim 12 wherein stoichiometric amounts of Co(NO 3 ) 4 and Na 2 WO 4 are combined.

14. The process of claim 12 wherein the exposing step is from 1 to 10 minutes.

15. The process of claim 12 wherein the exposing step includes elevating the solution to a temperature of from 200 to 300 degrees C.

16. The process of claim 12 including the step of cooling the solution following the exposing step.

17. The process of claim 12 further including the step of washing and drying the hydrated CoWO 4 following the hydrothermal reaction.

Assignees

• Toyota Eng & Mfg North America

Inventors

• Jia Hongfei
• Mcdonald Kenneth James

Classifications

• C01P2006/12

  Surface area · CPC title

• C01G51/40

  Complex oxides containing cobalt and at least one other metal element · CPC title

• C25B1/04

  by electrolysis of water · CPC title

• C01P2002/72

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

• C01P2004/64

  Nanometer sized, i.e. from 1-100 nanometer · CPC title