METAL HOLLOW FIBER ELECTRODE

Abstract

The invention is directed to a metal hollow fiber electrode, to a method of electrolyzing carbon dioxide in an aqueous electrochemical cell, to a method of converting carbon dioxide, to a method of preparing a metal hollow fiber, to a use of a metal hollow fiber electrode. The metal hollow fiber electrode comprises aggregated copper particles forming an interconnected three-dimensional porous structure, wherein said metal comprises copper.

Claims

1. A metal hollow fiber electrode, comprising aggregated copper particles forming an interconnected three-dimensional porous structure, wherein said metal comprises copper.

2. The metal hollow fiber electrode according to claim 1, wherein said metal is copper.

3. The metal hollow fiber electrode according to claim 1, wherein said fibers have an inner diameter of 0.1-10 mm.

4-5. (canceled)

6. The metal hollow fiber electrode according to claim 1, wherein said fibers have an outer diameter of 0.1-10 mm.

7-8. (canceled)

9. The metal hollow fiber electrode according to claim 1, wherein said fibers comprises or is composed of sintered copper particles.

10. The metal hollow fiber electrode according to claim 1, wherein said copper particles have an average particle diameter of 0.1-10 m.

11-12. (canceled)

13. The metal hollow fiber electrode according to claim 1, wherein a porous outer layer of the hollow fiber is more dense than a porous inner layer of the hollow fiber.

14. The metal hollow fiber electrode according to claim 1, wherein said outer layer has a thickness in the range of 5-20 m.

15-16. (canceled)

17. A method of electrolyzing carbon dioxide in an aqueous electrochemical cell comprising an anode and a cathode, wherein the cathode comprises one or more metal hollow fiber electrodes according to claim 1, said method comprising applying a potential between said anode and cathode, and purging CO.sub.2 or a gas mixture comprising CO.sub.2 through the wall of the metal hollow fiber electrode.

18. The method according to claim 17, wherein said method is performed in an aqueous environment.

19. The method according to claim 17, wherein said method is performed at a temperature in the range of 5-80 C.

20-21. (canceled)

22. A method of converting carbon dioxide into one or more selected from the group consisting of carbon monoxide, formic acid, a formate, methanol, acetaldehyde, methane, ethylene and ethane, comprising electrolyzing CO.sub.2 by a method according to claim 17.

23. The method according to claim 22, wherein carbon dioxide is converted into carbon monoxide.

24. A method of preparing a metal hollow fiber electrode according to claim 1, comprising spinning a mixture comprising copper particles, polymer and solvent together with a bore liquid to obtain hollow fibers; subjecting the hollow fibers to a thermal treatment such that copper particles are sintered together, thereby yielding hollow copper oxide fibers; hydrogenating the hollow copper oxide fibers.

25. The method according to claim 24, wherein said thermal treatment comprises subjecting the hollow fibers to a temperature of 500-800 C.

26. (canceled)

27. The method according to claim 24, wherein the hollow fibers are subjected to said thermal treatment for a period of 1-6 hours.

28. (canceled)

29. The method according to claim 24, wherein said hydrogenation comprises subjecting the hollow copper oxide fibers to a temperature of 200-400 C.

30. (canceled)

31. The method according to claim 24, wherein the hollow copper oxide fibers are hydrogenated for a period of 30-120 minutes.

32. (canceled)

33. The method according to claim 24, wherein the hollow copper oxide fibers are hydrogenated in a flow of hydrogen in the concentration range of 0-100 vol. %.

34. The method according to claim 24, wherein the hollow copper oxide fibers are hydrogenated in a flow of hydrogen in a concentration of 5 vol. % in a balance gas.

35. (canceled)

Description

BRIEF DESCRIPTION OF THE FIGURES

[0048] FIG. 1: Physical characterization of Cu hollow fibers. a) Low and b) High magnification SEM images of the outer surface of the Cu hollow fiber. c) Cross-sectional image of perpendicularly broken Cu hollow fiber. d) Outer surface of parallel broken Cu hollow fiber along with the cross-section. e) Image of Cu hollow fiber taken by the electron microscope, and f) Cu hollow fiber employed as an electrode (20 ml min.sup.1 gas flow and no applied potential.

[0049] FIG. 2: Electrocatalytic performance of Cu hollow fibers. a) Linear polarization curves for Cu hollow fiber under CO.sub.2 and Ar atmosphere in 0.3 M of KHCO.sub.3 (Scan rate 50 mV s.sup.1). b) Faradaic efficiency (FE) of CO, formic acid and H.sub.2 at different potentials. c) Overpotential vs. partial current density of CO for Cu hollow fiber. d) Total production of CO at an applied potential of 0.4 V for 24 hours of continuous experiment (flow rate of CO.sub.2: 20 ml min.sup.1).

[0050] FIG. 3: Electrocatalytic performance as a function of flow rate. a) Linear polarization curves for different flow rates of CO.sub.2 (Scan rate 50 mV s.sup.1). b) Faradaic efficiency (FE) of CO for different flow rates of CO.sub.2 and corresponding current densities (applied potential of 0.4 V vs. RHE, 0.3 M KHCO.sub.3. * Experiments are performed in CO.sub.2 saturated solutions.

[0051] FIG. 4: Activity of various electrodes in water: Overview of different catalysts' performance at different potentials with a plot of partial current density of CO at different potentials.

[0052] FIG. 5: XRD patterns of the starting copper powder, Cu hollow fiber after calcination at 600 C., and the copper fiber after hydrogenation.

[0053] FIG. 6: SEM image of as received copper powder.

[0054] FIG. 7: The faradaic efficiency (FE) of CO and total current density at an applied potential of 0.4 V for 24 hours of continuous experiment (flow rate of CO.sub.2: 20 ml min.sup.1).

[0055] FIG. 8: SEM images of the Cu hollow fibers after 24 hours of electrolysis.

[0056] FIG. 9: Reproducibility tests with 4 different fibers at a potential of 0.4 V vs. RHE. Flow rate of CO.sub.2: 20 ml min.sup.1.

[0057] FIG. 10: EDX analysis demonstrating the wt. % of electrodeposited nickel as a function of location from the outer surface. Deposition of Ni was achieved on the copper hollow fibers feeding 20 ml min.sup.1 of argon through the porous wall into the Ni.sup.2+ solution.

[0058] FIG. 11: SEM image of Cu hollow fiber showing the locations of the SEM images taken to construct FIG. 1.

[0059] FIG. 12: X-ray photoelectron spectroscopy survey for copper hollow fibers before electrolysis (includes 5 repeated scans).

[0060] FIG. 13: High-resolution X-ray photoelectron spectra demonstrating the Cu 2p peaks indicative of predominantly Cu.sup.0.

[0061] FIG. 14: High-resolution X-ray photoelectron spectrum of the Cu LMM region for Cu hollow fibers after electrolysis. Some Cu(I) might be present in the material.