Microbial fuel cell

• US 8,852,765 B2
• Filed: 03/27/2009
• Issued: 10/07/2014
• Est. Priority Date: 03/28/2008
• Status: Active Grant

• Current Assignee: Japan Science & Technology Trading Co. Limited, University of Tokyo
• Original Assignee: Japan Science & Technology Trading Co. Limited, University of Tokyo
• Inventors: Hashimoto, Kazuhito, Nakamura, Ryuhei, Kai, Fumiyoshi, Kato, Soichiro, Watanabe, Kazuya
• Primary Examiner(s): Ryan, Patrick
• Assistant Examiner(s): O DONNELL, LUCAS J
• Application Number:
  US12/934,876
• Publication Number:
  US 20110236725A1
• Time in Patent Office: 2,020 Days
• Field of Search: 429/2, 429/401
• US Class Current: 429/2
• CPC Class Codes: C12N 1/20 Bacteria; Culture media therefor
• CPC Class Codes: C12P 1/04 by using bacteria
• CPC Class Codes: C12P 3/00 Preparation of elements or inorganic compounds except carbon dioxide recovery of carbon dioxides as by-products C12F3/02
• CPC Class Codes: H01M 4/8605 Porous electrodes
• CPC Class Codes: H01M 4/8673 Electrically conductive fillers
• CPC Class Codes: H01M 4/90 Selection of catalytic material
• CPC Class Codes: H01M 8/16 Biochemical fuel cells, i.e. cells in which microorganisms function as catalysts
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

It is an object of the present invention to provide a microbial fuel cell capable of increasing a current density without employing a mediator. The microbial fuel cell 1 includes a 3-dimensionally structured agglomerate formed from conductive fine particles 2 and microorganisms 3. In the agglomerate 4, the conductive fine particles 2 disperse among pieces of Shewanella 3 and the conductive fine particles 2 are coupled to one another to hold Shewanella 3, thus forming the 3-dimensional structure as a whole. Accordingly, with respect to Shewanella 3, conductive fine particles 2 hold Shewanella 3a on a surface of an electrode 103 and even Shewanella 3b positioned vertically away from the surface of the electrode 103. Hence, it becomes possible that more pieces of Shewanella 3 are allowed to transfer electrons.

Claims

1. A microbial fuel cell equipped with a pair of electrodes and an external circuit electrically connecting a pair of said electrodes, wherein on a negative electrode that is one of said electrodes, 3-dimensionally structured agglomerates are spontaneously formed in a solution containing conductive fine particles and microorganisms with an extracellular electron transfer capability, said 3-dimensionally structured agglomerates being formed from said conductive fine particles and microorganisms by allowing said microorganisms to specifically adsorb said conductive fine particles;

and said microorganisms are held by said conductive fine particles over a range of zone extending vertically away from a surface of said negative electrode, in a manner such that said conductive fine particles are distributed among said microorganisms; and

said conductive fine particles comprise α

-Fe₂O₃, α

-FeOOH, γ

-Fe₂O₃, ε

-Fe₂O₃ or Fe₃O₄ or ferric sulfide, and then said conductive fine particles transfer electrons from said microorganisms to said negative electrode.

2. The microbial fuel cell according to claim 1, wherein said conductive fine particles include ferric oxide.

3. The microbial fuel cell according to claim 1, wherein said conductive fine particles are obtained by biosynthesis of microorganisms in an environment where ferric ions and sulfide ions coexist, said microorganisms being metal-reducing bacteria.

4. The microbial fuel cell according to claim 1, wherein said conductive fine particles include manganese oxide.

5. The microbial fuel cell according to claim 3, wherein said metal-reducing bacteria include bacteria of a Shewanella group, a Geobacter group, a Rhodoferax group or a Pseudomonas group.

6. The microbial fuel cell according to claim 3, wherein said metal-reducing bacteria contain Shewanella loihica or Shewanella oneidensis.

7. The microbial fuel cell according to claim 1, wherein said 3-dimensionally structured agglomerates are spontaneously formed by mixing said conductive fine particles and said microorganisms in said solution.

8. The microbial fuel cell according to claim 7, wherein said 3-dimensionally structured agglomerates comprises agglomerates of conductive fine particles.

9. The microbial fuel cell according to claim 1, wherein said 3-dimensionally structured agglomerates comprises agglomerates of conductive fine particles.

10. A method for manufacturing a negative electrode of a pair of electrodes used in a microbial fuel cell that is equipped with said pair of electrodes and an external circuit electrically connected thereto, comprising:

a step of preparing a solution for said negative electrode by mixing conductive fine particles and microorganisms with an extracellular electron transfer capability;

a step of allowing said conductive fine particles to hold said microorganisms over a range of zone extending vertically away from a surface of said negative electrode, in a manner such that said conductive fine particles disperse among said microorganisms and are further coupled to one another to hold said microorganisms; and

;

a step of causing 3-dimensionally structured agglomerates to be spontaneously formed by allowing said microorganisms to specifically adsorb said conductive fine particles.

11. The method for manufacturing the negative electrode according to claim 10, wherein said microorganisms are metal-reducing bacteria.

12. The method for manufacturing the negative electrode according to claim 11, wherein said metal-reducing bacteria include bacteria of a Shewanella group, a Geobacter group, a Rhodoferax group or a Pseudomonas group.

13. The method for manufacturing the negative electrode according to claim 11, wherein said metal-reducing bacteria contain Shewanella loihica or Shewanella oneidensis.

14. The method for manufacturing the negative electrode according to claim 10, wherein said conductive fine particles comprise α

-Fe₂O₃, α

-FeOOH, γ

-Fe₂O₃, ε

-Fe₂O₃ , Fe₃O₄or ferric sulfide.

15. The method for manufacturing the negative electrode according to claim 14, wherein said microorganisms are metal-reducing bacteria.

16. The method for manufacturing the negative electrode according to claim 15, wherein said metal-reducing bacteria include bacteria of a Shewanella group, a Geobacter group, a Rhodoferax group or a Pseudomonas group.

17. The method for manufacturing the negative electrode according to claim 15, wherein said metal-reducing bacteria contain Shewanella loihica or Shewanella oneidensis.