ELECTROCHEMICAL GAS SENSOR

Abstract

An electrochemical gas sensor is provided with a carbon-based measuring electrode (3) that it can be used for a large number of electrochemical detection reactions and can be manufactured at a low cost. The measuring electrode (3) contains carbon nanotubes.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a longitudinal sectional view of a first electrochemical gas sensor with an electrolyte-mediator mixture;

FIG. 2 is a second electrochemical gas sensor according to FIG. 1 with a protective electrode arranged coplanarly with the measuring electrode; and

FIG. 3 is the comparison of a conventional electrochemical gas sensor with precious metal electrodes with a gas sensor according to the present invention, which has a measuring electrode with carbon nanotubes.

Claims

1. An electrochemical gas sensor for detecting an analyte in a gas sample, the electrochemical gas sensor comprising: an electrolyte solution;a measuring electrode in said electrolyte solution, said measuring electrode containing carbon nanotubes; andan auxiliary electrode in said electrolyte solution.

2. An electrochemical gas sensor in accordance with claim 1, further comprising a structure comprising one of a porous carrier, a nonwoven material or a diffusion membrane, wherein said carbon nanotubes are located on said structure.

3. An electrochemical gas sensor in accordance with claim 1, wherein said carbon nanotubes are put together by self-aggregation or by means of a binder.

4. An electrochemical gas sensor in accordance with claim 3, wherein said binder is polytetrafluoroethylene (PTFE).

5. An electrochemical gas sensor in accordance with claim 1, wherein said carbon nanotubes are in the form of a film in the form of buckypaper.

6. An electrochemical gas sensor in accordance with claim 1, wherein said carbon nanotubes are in the form of single-wall carbon nanotubes with a layer thickness between 0.5 μm and 500 μm.

7. An electrochemical gas sensor in accordance with claim 1, wherein said carbon nanotubes are in the form of single-wall carbon nanotubes with a layer thickness between 10 μm to 50 μm.

8. An electrochemical gas sensor in accordance with claim 1, wherein said carbon nanotubes are in the form of multiwall carbon nanotubes with a layer thickness between 1 μm and 1,000 μm.

9. An electrochemical gas sensor in accordance with claim 1, wherein said carbon nanotubes are in the form of multiwall carbon nanotubes with a layer thickness between 50 μm and 150 μm.

10. An electrochemical gas sensor in accordance with claim 1, wherein said auxiliary electrode consists of a precious metal.

11. An electrochemical gas sensor in accordance with claim 1, wherein said auxiliary electrode comprises at least one of gold, platinum or iridium or carbon nanotubes.

12. An electrochemical gas sensor in accordance with claim 1, wherein a reference electrode is additionally present.

13. An electrochemical gas sensor in accordance with claim 1, wherein a protective electrode is arranged behind said measuring electrode.

14. An electrochemical gas sensor in accordance with claim 1, wherein molecular structures with catalytic activity or mediator properties are bound to said carbon nanotubes.

15. An electrochemical gas sensor in accordance with claim 14, wherein said molecular structures contain transition metals like one of Fe, Ni, Co, or corresponding metal oxides.

16. An electrochemical gas sensor in accordance with claim 14, wherein said molecular structures contain transition metal complexes including at least one of porphyrins or phthalocyanines.

17. An electrochemical gas sensor in accordance with claim 1, wherein said electrolyte solution is present as an aqueous or organic electrolyte.

18. An electrochemical gas sensor in accordance with claim 17, wherein said organic electrolyte solution is selected from the group of carbonates.

19. An electrochemical gas sensor in accordance with claim 17, wherein said organic electrolyte solution comprises propylene carbonate mixed with ethylene carbonate and/or higher carbonates.

20. An electrochemical gas sensor in accordance with claim 1, wherein said electrolyte solution contains a mediator compound, said mediator compound being an acid compound, said acid compound containing either at least two acid groups or at least one hydroxyl group and at least one acid group.

21. An electrochemical gas sensor in accordance with claim 20, wherein the acid compound is a carboxylic acid.

22. An electrochemical gas sensor in accordance with claim 21, wherein said carboxylic acid is an aromatic carboxylic acid containing two or three carboxyl groups.

23. An electrochemical gas sensor in accordance with claim 22, wherein said carboxyl groups comprise phthalic acid, isophthalic acid or terephthalic acid.

24. An electrochemical gas sensor in accordance with claim 16, wherein acid compound is an aliphatic polycarboxylic acid, especially citric acid.

25. An electrochemical gas sensor in accordance with claim 20, wherein the acid compound is gluconic acid.

26. An electrochemical gas sensor in accordance with claim 20, wherein the acid compound is boric acid.

27. An electrochemical gas sensor in accordance with claim 20, wherein said electrolyte solution contains alkali or alkaline earth metal salts, preferably LiCl.

28. An electrochemical gas sensor in accordance with claim 20, wherein water or organic solvents, ethylene and/or propylene carbonate, are used as a solvent.

29. An electrochemical gas sensor in accordance with claim 20, wherein a transition metal salt is a copper salt or Cu2+ salt.

30. An electrochemical gas sensor in accordance with claim 29, wherein the Cu2+ salt is CuCl2 and the concentration of CuCl2 is between one of 0.1 mol and 1.0 mol, 0.5 mol in a 0.5-10-molar preferably 5-molar LiCl solution.

31. An electrochemical gas sensor in accordance with at least claim 20, wherein a transition metal salt is an iron salt or Fe3+ salt.

32. A method of electrochemical gas sensing, the method comprising: providing an electrolyte solution;providing a measuring electrode in said electrolyte solution, said measuring electrode containing carbon nanotubes; andproviding an auxiliary electrode in said electrolyte solution.

33. A method of electrochemical gas sensing in accordance with claim 32, further comprising: determining SO2 concentration in a gas wherein the electrolyte is or contains a chloride.

34. A method of electrochemical gas sensing in accordance with claim 32, further comprising; determining H2S concentration in a gas wherein said electrolyte is or contains a chloride.