Metal-alloy graphene nanocomposites and methods for their preparation and use

Patent metadata

Field	Value
Publication number	US-9847534-B2
Application number	US-201214397197-A
Country	US
Kind code	B2
Filing date	Aug 8, 2012
Priority date	Apr 26, 2012
Publication date	Dec 19, 2017
Grant date	Dec 19, 2017

Abstract

Methods of forming a metal-alloy graphene nanocomposites are provided. The methods include providing a graphene substrate and forming a conducting polymer layer on a first major surface of the graphene substrate. The methods also include pyrolyzing the conducting polymer layer to form a nitrogen-doped graphene substrate and dispersing a plurality of metal-alloy nanoparticles on a first surface of the nitrogen-doped graphene substrate to form the nanocomposite.

First claim

We claim:

1. A method of forming a metal-alloy graphene nanocomposite, the method comprising:
providing a graphene substrate;
forming a conducting polymer layer on a first major surface of the graphene substrate;
pyrolyzing the conducting polymer layer to form a nitrogen-doped graphene substrate; and
dispersing a plurality of metal-alloy nanoparticles on a first surface of the nitrogen-doped graphene substrate to form the nanocomposite.

2. The method of claim 1 , wherein the conducting polymer layer comprises polypyrrole (PPy), polyaniline (PANI), polycarbazole, polyindole, polyazepine, or combinations thereof.

3. The method of claim 1 , wherein the plurality of metal-alloy nanoparticles comprises a combination of platinum (Pt) and an alloying transition metal.

4. The method of claim 3 , wherein the alloying transition metal is a 3d transition metal.

5. The method of claim 3 , wherein the alloying transition metal comprises cobalt (Co), iron (Fe), nickel (Ni), or combinations thereof.

6. The method of claim 1 , wherein forming the conducting polymer layer comprises:
functionalizing the graphene substrate with a negatively charged polyelectrolyte to form a functionalized graphene substrate; and
polymerizing the functionalized graphene substrate using a polymerizable heterocyclic aromatic compound to form a positively charged conducting polymer layer on the graphene substrate.

7. The method of claim 6 , wherein the negatively charged polyelectrolyte comprises poly(sodium 4-styrene sulfonate) (PSSS), sodium polyarylate, polyanetholesulfonic acid sodium salt, poly(2-acrylamido-2-methyl-1-propanesulfonic acid-co-acrylonitrile), poly(2-acrylamido-2-methyl-1-propanesulfonic acid) solution, poly(vinyl sulfate) potassium salt, poly(vinylsulfonic acid, sodium salt) solution, 4-styrenesulfonic acid sodium salt hydrate, poly(4-styrenesulfonic acid-co-maleic acid) sodium salt solution, or combinations thereof.

8. The method of claim 6 , wherein the polymerizable heterocyclic aromatic compound comprises pyrrole, aniline, carbazole, indole, azepine, or combinations thereof.

9. The method of claim 1 , wherein pyrolyzing the conducting polymer layer comprises heating the graphene substrate with the polymer layer in presence of an inert gas to form the nitrogen-doped graphene substrate.

10. The method of claim 1 , wherein the plurality of metal-alloy nanoparticles is dispersed on the nitrogen-doped graphene substrate by a polyol reduction technique in presence of a reducing agent.

11. A method of forming a metal-alloy graphene nanocomposite, the method comprising:
providing a graphene substrate;
functionalizing the graphene substrate with a negatively charged polyelectrolyte to form a functionalized graphene substrate;
polymerizing the functionalized graphene substrate using a polymerizable heterocyclic aromatic compound to form a positively charged conducting polymer layer on the graphene substrate; and
pyrolyzing the conducting polymer layer to form a nitrogen-doped graphene substrate.

12. The method of claim 11 , further comprising dispersing a plurality of metal-alloy nanoparticles on a first major surface of the nitrogen-doped graphene substrate to form the nanocomposite.

13. The method of claim 11 , wherein the conducting polymer layer comprises polypyrrole (PPy), polyaniline (PANI), polycarbazole, polyindole, polyazepine, or combinations thereof.

14. The method of claim 11 , wherein the negatively charged polyelectrolyte comprises poly(sodium 4-styrene sulfonate) (PSSS), sodium polyacrylate, polyanetholesulfonic acid sodium salt, poly(2-acrylamido-2-methyl-1-propanesulfonic acid-co-acrylonitrile), poly(2-acrylamido-2-methyl-1-propanesulfonic acid) solution, poly(vinyl sulfate) potassium salt, poly(vinylsulfonic acid, sodium salt) solution, 4-styrenesulfonic acid sodium salt hydrate, poly(4-styrenesulfonic acid-co-maleic acid) sodium salt solution, or combinations thereof.

15. The method of claim 11 , wherein the polymerizable heterocyclic aromatic compound comprises pyrrole, aniline, carbazole, indole, azepine, or combinations thereof.

16. The method of claim 11 , wherein pyrolyzing the conducting polymer layer comprises heating the graphene substrate with the polymer layer in presence of an inert gas to form the nitrogen-doped graphene substrate.

17. A metal-alloy graphene nanocomposite comprising:
a nitrogen-doped graphene substrate; and
a plurality of metal-alloy nanoparticles dispersed on a first major surface of the nitrogen doped graphene substrate,
wherein the nitrogen-doped graphene substrate is formed by coating a conducting polymer layer on a first major surface of a graphene substrate and pyrolyzing the conducting polymer layer to form the nitrogen-doped graphene substrate.

18. The metal-alloy graphene nanocomposite of claim 17 , wherein the conducting polymer layer comprises polypyrrole (PPy), polyaniline (PANI), polycarbazole, polyindole, polyazepine, or combinations thereof.

19. The metal-alloy graphene nanocomposite of claim 17 , wherein an atomic percentage of nitrogen in the nitrogen-doped graphene substrate is about 4% to about 8%.

20. The metal-alloy graphene nanocomposite of claim 19 , wherein the atomic percentage of nitrogen in the nitrogen-doped graphene substrate is about 6%.

21. The metal-alloy graphene nanocomposite of claim 17 , wherein the plurality of metal-alloy nanoparticles comprises a combination of platinum (Pt) and an alloying transition metal.

22. The metal-alloy graphene nanocomposite of claim 21 , wherein the alloying transition metal comprises cobalt (Co), iron (Fe), nickel (Ni), or combinations thereof.

23. The metal-alloy graphene nanocomposite of claim 21 , wherein the plurality of metal-alloy nanoparticles comprises platinum and cobalt having an atomic ratio of about 3:1.

24. The metal-alloy graphene nanocomposite of claim 17 , wherein the nanocomposite is configured as an electrocatalyst for use in a proton exchange membrane fuel cell (PEMFC).

25. An electrocatalyst, comprising:
a nitrogen-doped graphene substrate; and
a plurality of platinum-cobalt alloy nanoparticles dispersed on a first major surface of the nitrogen-doped graphene substrate,
wherein an atomic ratio of platinum and cobalt in the plurality of platinum-cobalt alloy nanoparticles is about 3:1.

26. The electrocatalyst of claim 25 , wherein the weight of the plurality of platinum-cobalt alloy nanoparticles is about 30% of the total weight of the electrocatalyst.

27. The electrocatalyst of claim 25 , wherein an average size of the platinum-cobalt alloy nanoparticles is about 2.2 nanometers to about 2.8 nanometers.

28. The electrocatalyst of claim 25 , wherein a current density of the electrocatalyst measured at a potential of about 0.5 Volts (V) is about 1560 mA cm −2 .

29. The electrocatalyst of claim 25 , wherein a power density of the electrocatalyst at a temperature of about 60° C. is about 805 mW cm −2 .

30. The electrocatalyst of claim 25 , wherein the electrocatalyst is configured as an electrode of a proton exchange membrane fuel cell (PEMFC).

31. An electrocatalyst formed by providing a nitrogen-doped graphene substrate and dispersing a plurality of platinum-cobalt alloy nanoparticles on a first surface of the nitrogen-doped graphene substrate, wherein providing the nitrogen-doped

Assignees

• Sundara Ramaprabhu
• Parambath Vinayan Bhaghavathl
• Nagar Rupali
• Natarajan Rajalakshmi
• Indian Institute Of Tech Madras

Inventors

• Sundara Ramaprabhu
• Parambath Vinayan Bhaghavathl
• Nagar Rupali
• Natarajan Rajalakshmi

Classifications

• B05D3/0254

  After-treatment · CPC title

• H01M4/8657

  layered · CPC title

• H01M2008/1095

  Fuel cells with polymeric electrolytes · CPC title

• B05D7/548

  No curing step for the last layer · CPC title

• B05D1/38

  with intermediate treatment (intermediate treatment per se B05D3/00) · CPC title