ELECTRODE AND SENSOR HAVING CARBON NANOSTRUCTURES

• US 20110102002A1
• Filed: 09/23/2010
• Published: 05/05/2011
• Est. Priority Date: 04/09/2008
• Status: Abandoned Application

• Current Assignee: Riehl-Johnson Holdings, LLC
• Original Assignee: Riehl-Johnson Holdings, LLC
• Inventors: Riehl, Bonnie D., King, Edward E., Johnson, Jay M., Schlueter, Kevin T., Riehl, Bill L.
• Application Number:
  US12/889,019
• Publication Number:
  US 20110102002A1
• Time in Patent Office: Days
• US Class Current: 324/693
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: C01B 32/15 Nano-sized carbon materials
• CPC Class Codes: C01B 32/156 After-treatment
• CPC Class Codes: G01N 27/3277 being a redox reaction, e.g. detection by cyclic voltammetry voltammetry per se G01N27/42, G01N27/48
• CPC Class Codes: H01G 11/22 Electrodes
• CPC Class Codes: H01G 11/36 Nanostructures, e.g. nanofibres, nanotubes or fullerenes
• CPC Class Codes: H01M 8/16 Biochemical fuel cells, i.e. cells in which microorganisms function as catalysts
• CPC Class Codes: Y02E 60/13 Energy storage using capacitors
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

An active electrode structure is disclosed that includes fullerenes produced by a carbo-thermal carbide conversion of a conductive carbide without a metal catalyst. Also disclosed is an electrode that includes a fullerene covalently bonded to a conductive carbide, the fullerene being an aligned or non-aligned array. The carbide substrate having a surface coating of covalently bonded fullerenes is characterized in that the peak separation of a cyclic voltammogram for the conductive carbide having a surface layer of the fullerene is less than about 150 mV at a scan rate of 5 mV/s in a 4 mM ferricyanide, 1M KCl solution. The fullerene may include about 50% or less non-crystalline carbon and about 5% or less of a transition metal that interferes with the ability of the active electrode structure to transfer electrons or detect an analyte.

Claims

1. An electrode comprising:

a fullerene covalently bonded to a conductive carbide, the fullerene being an aligned or non-aligned array;

wherein the electrode is characterized in that the peak separation of a cyclic voltammogram for the conductive carbide having a surface layer of the fullerene is less than about 150 mV at a scan rate of 5 mV/s in a 4 mM ferricyanide, 1M KCl solution.

2. The electrode of claim 1 wherein the peak separation is less than about 100 mV.

3. The electrode of claim 1 wherein the peak separation is less than about 75 mV.

4. The electrode of claim 1 wherein the peak separation is less than about 65 mV.

5. The electrode of claim 1 wherein the peak separation is about 150 to 59.1 mV.

6. The electrode of claim 1 further comprising about 50% or less non-crystalline carbon and about 5% or less of a transition metal that interferes with the ability of the active electrode structure to transfer electrons or detect an analyte.

7. The electrode of claim 2 wherein the transition metal is about 1% or less of the active electrode structure.

8. The electrode of claim 2 wherein the non-crystalline carbon is about 5% or less of the active electrode structure.

9. The electrode of claim 2 wherein the non-crystalline carbon is about 1% or less of the active electrode structure.

10. The electrode of claim 1 wherein the conductive carbide, prior to having the fullerene covalently bonded thereto, has an ohmic resistance of less than about 5000 Ω

/sq.

11. The electrode of claim 10 wherein the conductive carbide has an ohmic resistance of less than about 1000 Ω

/sq.

12. The electrode of claim 11 wherein the conductive carbide has an ohmic resistance of less than about 100 Ω

/sq.

13. The electrode of claim 12 wherein the conductive carbide has an ohmic resistance of less than about 10 Ω

/sq.

14. The electrode of claim 13 wherein the conductive carbide has an ohmic resistance of less than about 10 Ω

/sq.

15. The electrode of claim 14 wherein the conductive carbide has an ohmic resistance of less than about 0.1 Ω

/sq.

16. The electrode of claim 1 further comprising an electrical lead electrically conductively coupled to the conductive carbide.

17. The electrode of claim 16 wherein the active electrode structure further comprises at least one of a binder, a filler, and combinations thereof.

18. The electrode of claim 1 wherein the fullerene is a non-aligned, entangled array.

19. The electrode of claim 18 wherein the fullerene is formed by a carbo-thermal carbide conversion that is essentially free of metal catalyst.

20. The electrode of claim 19 wherein the metal catalyst is present in an amount less than about 500 ppm.

21. The electrode of claim 20 wherein the metal catalyst is present in an amount less than about 100 ppm.

22. The electrode of claim 1 wherein the carbide includes silicon carbide.

23. The electrode of claim 22 wherein the silicon carbide is an n-doped silicon carbide.

24. The electrode of claim 1 wherein the fullerenes are selected from the group consisting of carbon nanotubes, carbon nanorods, or combinations thereof.

25. The electrode of claim 24 wherein the fullerenes display high edge plane character.

26. The electrode of claim 25 including 0.1% or less of a non-crystalline carbon and 0.1% or less of a metal catalyst.

27. The electrode of claim 26 characterized by a G band Raman signature to G* band Raman signature of about 10:

1 to about 1;

5 at 514 nm excitation and of about 12;

1 to about 1;

5 at 758 nm excitation.

28. The electrode of claim 1 wherein the carbide has at least a 30% crystalline carbide content.

29. The electrode of claim 1 wherein the carbide has at least a 70% crystalline carbide content.

30. The electrode of claim 1 wherein the carbide has at least a 99% crystalline carbide content.

31. The electrode of claim 1 wherein the fullerenes include a 2-dimensional array of fullerenes.

32. The electrode of claim 1 wherein the conductive carbide is substantially converted to fullerenes such that the fullerenes are a free standing mass of fullerenes.

33. The electrode of claim 1 wherein the fullerene is modified to include a transition metal that enhances the ability of the active electrode structure to transfer electrons or detect an analyte, provided that the transition metal does not function as a metal catalyst for fullerene growth.

34. The electrode of claim 33 wherein the transition metal is a noble metal.

35. An active electrode structure comprising:

a fullerene covalently bonded to a conductive carbide, wherein the conductive carbide, prior to having the fullerene covalently bonded thereto, has an ohmic resistance of less than about 5000 Ω

/sq.

36. The active electrode structure of claim 35 wherein the conductive carbide has an ohmic resistance of less than about 100 Ω

/sq.

37. The active electrode structure of claim 35 wherein the conductive carbide has an ohmic resistance of less than about 10 Ω

/sq.

38. The active electrode structure of claim 35 wherein the conductive carbide has an ohmic resistance of less than about 1 Ω

/sq.

39. The active electrode structure of claim 35 wherein the fullerenes comprise about 50% or less non-crystalline carbon and about 5% or less of a transition metal that interferes with the ability of the active electrode structure to transfer electrons or detect an analyte.

40. The active electrode structure of claim 39 wherein the transition metal is about 1% or less of the active electrode structure.

41. The active electrode structure of claim 39 wherein the non-crystalline carbon is about 5% or less of the active electrode structure.

42. The active electrode structure of claim 39 wherein the non-crystalline carbon is about 1% or less of the active electrode structure.

43. The active electrode structure of claim 35 wherein the fullerene is a non-aligned, entangled array.

44. The active electrode structure of claim 35 wherein the fullerene is formed from the carbide substantially without a metal catalyst.

45. The active electrode structure of claim 44 wherein the metal catalyst is present in an amount less than 500 ppm.

46. The active electrode structure of claim 45 wherein the metal catalyst is less than about 1 ppm of the active electrode structure.

47. The active electrode structure of claim 35 wherein the carbide includes silicon carbide.

48. The active electrode structure of claim 35 wherein the conductive carbide is substantially converted to fullerenes such that the fullerenes are a free standing mass of fullerenes.

49. A sensor comprising:

a fullerene covalently bonded to a conductive carbide, the fullerene being an aligned or non-aligned array;

wherein the carbide having a surface coating of the fullerene is characterized in that the peak separation of a cyclic voltammogram for the conductive carbide having a surface layer of the fullerene is less than about 150 mV at a scan rate of 5 mV/s in a 4 mM ferricyanide, 1M KCl solution;

wherein the active electrode structure further comprises a protein coupled to the fullerene.

50. A sensor of claim 49 wherein the protein provides the active electrode structure with the capability of detecting nitrate

51. The sensor of claim 50 wherein the protein includes a heme group.

52. The sensor of claim 51 wherein the protein includes nitrate reductase.

53. The sensor of claim 52 wherein the nitrate reductase is a simplified eukaryotic nitrate reductase.

54. The sensor of claim 49 wherein the peak separation is less than about 75 mV.

55. The sensor of claim 49 wherein the peak separation is about 59.1 mV.

56. The sensor of claim 49 wherein the conductive carbide, prior to having the fullerene covalently bonded thereto, has an ohmic resistance of less than about 100 Ω

/sq.

57. The sensor of claim 49 wherein the conductive carbide, prior to having the fullerene covalently bonded thereto, has an ohmic resistance of less than about 10 Ω

/sq.

58. The sensor of claim 49 wherein the conductive carbide, prior to having the fullerene covalently bonded thereto, has an ohmic resistance of less than about 1 Ω

/sq.

59. A process for detecting or quantifying an analyte in a test solution, the process comprising;

placing an electrode in a test solution containing an analyte, the electrode including fullerenes produced by conversion from a carbide;

depositing the analyte on the electrode by operating the electrode at a potential that deposits the analyte on the electrode;

electrochemically stripping the analyte from the electrode by voltammetric scanning of the electrode through a range of potentials that progressively removes the analyte; and

determining the identity of the analyte based upon the voltage at which the analyte is stripped from the electrode.

60. The process of claim 59 wherein determining the identity of the analyte includes correlating a measurement corresponding to a change in oxidation state of the analyte to its identity.

61. The process of claim 59 wherein quantifying that amount of the analyte present includes determining the peak height (current) or integrated peak current (charge) from a graph of the differential current versus the electric potential.