JP2021099977A - Composition for forming microbial fuel cell electrode, electrode and fuel cell - Google Patents

Abstract

To provide an inexpensive electrode-forming composition for manufacturing an electrode for a microbial fuel cell, which is excellent in water penetration resistance and power generation characteristics.SOLUTION: The problem can be solved by a silicone-containing resin composition for electrode formation, that is, a composition for forming a microbial fuel cell electrode, which contains a conductive material and/or an oxygen reduction catalyst and silicone. In the composition for forming a microbial fuel cell electrode, silicone is silicone oil, or polydimethylsiloxane. The composition for forming a microbial fuel cell electrode further contains a binder resin.SELECTED DRAWING: None

Description

The present invention relates to electrode-forming compositions, electrodes and fuel cells used in microbial fuel cells.

In recent years, with the spread of secondary batteries, portable electronic devices such as mobile phones, laptop computers and tablet terminals have become widespread. In particular, lithium-ion secondary batteries have come to be used as high-output power sources for vehicles because they can obtain a larger energy density than batteries such as lead-acid batteries, nickel-cadmium batteries, and nickel-metal hydride batteries. In addition, research on power generation devices as a power source that does not require charging is being actively conducted, and hydrogen-fueled stationary fuel cells and in-vehicle fuel cells have also come into practical use.

On the other hand, in recent years, the development of biofuel cells using the mechanism of fuel cells has been promoted, and there are biofuel cells using biocatalytic enzymes, microbial fuel cells using microorganisms, and the like. Microbial fuel cells are a power generation method that collects electrons generated when organic matter is decomposed by microorganisms called power generation bacteria and uses them as electrical energy.

Two-tank type and one-tank type are known as configurations of the microbial fuel cell (Patent Document 1, Non-Patent Document 1). It is common that electrons generated from the decomposition reaction by microorganisms at the negative electrode pass through an external circuit and are consumed in the reduction reaction at the positive electrode. In the two-tank type, both electrodes are separated by a partition wall such as an ion exchange membrane, and an oxidizing agent such as oxygen or potassium ferricyanide is reacted at the positive electrode. On the other hand, the one-tank type has no partition wall, and the positive electrode and the negative electrode are arranged in one tank, and oxygen in the atmosphere is used as an oxidizing agent to react with the positive electrode.

Microbial fuel cells are expected as a water treatment method that can reduce energy consumption because, for example, decomposition treatment of organic substances in domestic wastewater and power generation can be performed in parallel (Non-Patent Document 2).
When a microbial fuel cell is used as such a water treatment method, if the electrode is flooded, its power generation performance is significantly deteriorated. Therefore, a method has been adopted in which water repellent treatment is applied to one side of the electrode to suppress the flooding. Patent Document 2).
However, this method has a problem that the water repellency of the catalyst layer in the electrode is insufficient, the electrode is flooded with the passage of time, and the power generation characteristics are deteriorated (Patent Document 3). In addition, it is necessary to apply a water-repellent treatment to one side of the electrode, which increases the cost.

Japanese Unexamined Patent Publication No. 2004-342212 WO2016 / 063455 Japanese Unexamined Patent Publication No. 2015-046361

Environmental Science & Technology, 2004, 38, 4040-4046 Forefront of wastewater treatment system using microbial fuel cell, NTS Co., Ltd.

An object of the present invention is to provide an electrode-forming composition for producing an electrode for a microbial fuel cell having excellent water immersion resistance and power generation characteristics, and an inexpensive electrode-forming composition.

The present inventors have reached the present invention as a result of repeated diligent studies to solve the above-mentioned problems.
That is, the present invention relates to a composition for forming a microbial fuel cell electrode containing a conductive material and / or an oxygen reduction catalyst and silicone.

The present invention also relates to the above-mentioned composition for forming a microbial fuel cell electrode in which silicone is a silicone oil.

The present invention also relates to the above-mentioned composition for forming a microbial fuel cell electrode in which silicone is polydimethylsiloxane.

The present invention further relates to the above-mentioned composition for forming a microbial fuel cell electrode containing a binder resin.

The present invention also relates to the above-mentioned composition for forming a microbial fuel cell electrode in which the binder resin contains aqueous resin fine particles.

The present invention further relates to the above-mentioned composition for forming a microbial fuel cell electrode containing a dispersant.

The present invention also relates to the above-mentioned composition for forming a microbial fuel cell electrode, wherein the oxygen reduction catalyst is one or more selected from the group consisting of a noble metal catalyst, a base metal oxide catalyst, and a carbon catalyst.

The present invention further relates to the above-mentioned composition for forming a microbial fuel cell electrode containing a solvent.

The present invention also relates to an electrode for a microbial fuel cell, which comprises a base material and a layer formed from the composition for forming a microbial fuel cell electrode.

The present invention also relates to a microbial fuel cell, which comprises the above-mentioned electrode for a microbial fuel cell.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an electrode forming composition for producing an electrode for a microbial fuel cell excellent in water immersion resistance and power generation characteristics, and an inexpensive microbial fuel cell electrode forming composition.

The composition for forming an electrode of a microbial fuel cell of the present invention (hereinafter, also referred to as an electrode forming composition or a mixture ink) has an increased oxygen supply (gas path) and proton supply (proton path) per unit volume of the catalyst layer. However, the water immersion resistance can be improved by forming a plurality of paths.
Therefore, by using the electrode-forming composition of the present invention, it is possible to reduce the amount of expensive materials and peripheral members used while maintaining the power generation characteristics, and an inexpensive and high-performance electrode-forming composition is provided. It can greatly contribute to the spread of microbial fuel cells.

Hereinafter, embodiments of the present invention will be described in detail.

<Composition for forming microbial fuel cell electrodes (mixture ink)>
The electrode-forming composition of the present invention contains at least a conductive material and / or an oxygen reduction catalyst (A) and silicone, and forms a layer on a base material to form a part of an electrode of a microbial fuel cell.
If necessary, the electrode-forming composition of the present invention includes a binder resin (B), a dispersant, a solvent, a thickener, a film-forming aid, an antifoaming agent, a leveling agent, a preservative, a pH adjuster, etc. May include. A plurality of types may be used for each of these.
From the viewpoint of VOC discharge, it is preferable to use water or an aqueous solvent as the solvent, and when a binder resin (B), a dispersant and the like are contained, these are also preferably aqueous.

<Conductive material>
The electrode-forming composition of the present invention contains at least one of a conductive material and an oxygen reduction catalyst. When the electrode-forming composition of the present invention is used as a layer (so-called anchor layer) for conducting a layer containing an oxygen reduction catalyst and a base material, it may contain a conductive material but may not contain an oxygen reduction catalyst.

The conductive material is mainly contained to enhance the electron conductivity in the microbial fuel cell electrode and facilitate the redox reaction. A carbon material is preferable, but the material is not limited to this, and silver nanoparticles, an ionic liquid, or the like may be used if necessary.
The conductive material may be particles or non-particles having a binder function.

The carbon material which is a conductive material that can be used in the present invention is not particularly limited as long as it is a conductive carbon material, but carbon black, graphite, activated carbon, and conductive carbon fibers (carbon nanotubes, carbon). Nanofibers, carbon fibers, carbon nanohorns), graphite, fullerene, etc. can be used alone or in combination of two or more.

Carbon black includes furnace black, which is produced by continuously pyrolyzing a gas or liquid raw material in a reactor, especially acetylene black, which is made from ethylene heavy oil, and the raw material gas is burned to burn the flame to the bottom of the channel steel. Various types such as channel black that has been rapidly cooled and precipitated, thermal black that is obtained by periodically repeating combustion and thermal decomposition using gas as a raw material, and acetylene black that uses acetylene gas as a raw material, alone or 2 More than one type can be used together. In addition, normally oxidized carbon black, hollow carbon, and the like can also be used.

As the specific surface area of the carbon black used increases, the contact points between the carbon black particles increase, which is advantageous in reducing the internal resistance of the electrode. Specifically, the specific surface area (BET) obtained from the amount of nitrogen adsorbed is 20 m ² / g or more and 5000 m ² / g or less, preferably 50 m ² / g or more, 2000 m ² / g or less, and ^{more preferably 50 m 2} It is desirable to use the one of / g or more and 1500 m ^{2 / g or less.}

When the carbon black used contains particles, the particle size thereof is preferably 0.005 to 1 μm in terms of the primary particle size, and particularly preferably 0.01 to 0.2 μm. However, in the present specification, the primary particle size is an average of the particle sizes measured by an electron microscope or the like.
When the conductive material is non-particles or contains both particles and non-particles, the particle size of the non-particles is naturally not measured.

When the carbon material as the conductive material is contained as particles, it is desirable that the dispersed particle size in the mixture ink is finely divided to 0.03 μm or more and 5 μm or less.
In the present specification, the dispersed particle size is the particle size (D-50) at which the volume ratio of the particles is 50% when the volume ratio of the particles is integrated from the fine particle size distribution in the volume particle size distribution. , A general particle size distribution meter, for example, a dynamic light scattering type particle size distribution meter (“Microtrack UPA” manufactured by Nikkiso Co., Ltd.) or the like.

Examples of commercially available carbon black include Talker Black # 4300, # 4400, # 4500, # 5500 (Tokai Carbon Co., Ltd., Furness Black), Graphite L, etc. (Degusa Co., Ltd., Furness Black), Raven7000, 5750, etc. 5250, 5000 ULTRAIII, 5000 ULTRA, etc., Conductex SC ULTRA, Conductex 975 ULTRA, etc., PUER BLACK100, 115, 205, etc. (Columbian, Furness Black), # 2350, # 2400B, # 2600B, # 3050B, # 3030B, # 3050B, # 30 # 3350B, # 3400B, # 5400B, etc. (manufactured by Mitsubishi Chemical Co., Ltd., Furness Black), MONARCH1400, 1300, 900, VulcanXC-72R, BlackPearls2000, etc. (manufactured by Cabot Co., Ltd., Furness Black), Ensaco250G, Ensaco260G, Ensaco350G, Super TIMCAL), MA7, MA11, MA14, MA77, MA100, MA100S (manufactured by Mitsubishi Chemical), Ketjen Black EC-300J, EC-600JD (manufactured by Lion Specialty Chemicals), Denka Black, Denka Black HS Examples of graphite such as -100 and FX-35 (manufactured by Denka, acetylene black) include, but are limited to, natural graphite such as artificial graphite, flake graphite, lump graphite, and earth graphite. Instead, two or more types may be used in combination.

Specific examples of the activated carbon include activated carbons activated by phenol-based, coconut husk-based, rayon-based, acrylic-based, coal-petroleum-based pitch coke, mesocarbon microbeads (MCMB), and the like. Those having a large specific surface area, which can form an interface having a wider area even with the same mass, are preferable.

As the conductive carbon fiber, those obtained by firing from a raw material derived from petroleum are preferable, but those obtained by firing from a raw material derived from a plant can also be used. For example, VGCF manufactured by Showa Denko KK, which is manufactured from petroleum-derived raw materials, can be mentioned.

<Oxygen reduction catalyst>
The electrode-forming composition of the present invention contains at least one of a conductive material and an oxygen reduction catalyst (hereinafter, also referred to as a catalyst). Examples of the oxygen reduction catalyst include a noble metal catalyst, a base metal oxide catalyst, and a carbon catalyst. These may be used alone or in combination of two or more. The oxygen reduction catalyst is preferably particles, but may not be particles.

(Precious metal catalyst)
The noble metal catalyst is a catalyst containing at least one element selected from ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, and gold among transition metal elements. These noble metal catalysts may be simple substances or supported on another element or compound. Among them, a catalyst-supported carbon material is a good example. The catalyst-supported carbon material refers to a material in which catalyst particles are supported on a carbon material as a catalyst carrier, and there are known or commercially available materials.

The carrying ratio of the catalyst particles on the carbon material as the catalyst carrier is not limited. When platinum is used as the catalyst particles, the catalyst particles can usually be supported in an amount of about 1 to 70% by mass with respect to a total of 100% by mass of the catalyst particles and the carbon material as the catalyst carrier.

The carbon material as the catalyst carrier used in the present invention is not particularly limited as long as it is a carbon particle derived from an inorganic material and / or a carbon particle obtained by heat-treating an organic material.
Carbon particles derived from inorganic materials include carbon black (furness black, acetylene black, ketjen black, medium thermal carbon black), activated carbon, graphite, carbon nanotubes, carbon nanofibers, carbon nanohorns, graphene nanoplatelets, nanoporous carbon, etc. Examples include carbon fiber. Carbon materials have various physical properties and costs such as particle size, shape, BET specific surface area, pore volume, pore size, bulk density, DBP oil absorption, surface acid basicity, surface hydrophilicity, and conductivity, depending on the type and manufacturer. Since they are different, the optimum material is selected according to the intended use and required performance.

The organic material that becomes carbon particles by heat treatment is not particularly limited as long as it is a material that becomes carbon particles after heat treatment. Specific organic materials include phenol-based resin, polyimide-based resin, polyamide-based resin, polyamideimide-based resin, polyacrylonitrile-based resin, polyaniline-based resin, phenolformaldehyde resin-based resin, polyimidazole-based resin, polypyrrole-based resin, and poly. Examples thereof include benzoimidazole-based resins, melamine-based resins, pitches, brown charcoal, polycarbodiimide, biomass, proteins, fumic acid and the like, and derivatives thereof.
These carbon materials are used in one kind or two or more kinds.

As a commercially available catalyst-supported carbon material, for example, platinum-supported carbon particles such as TEC10E50E, TEC10E70TPM, TEC10V30E, TEC10V50E, and TEC66E50 manufactured by Tanaka Kikinzoku Kogyo Co., Ltd .; platinum-ruthenium alloy-supported carbon particles such as TEC66E50 and TEC62E58; However, it is not limited to these.

(Base metal oxide catalyst)
The base metal oxide catalyst used in the present invention is at least one selected from the group consisting of zirconium, tantalum, titanium, niobium, vanadium, iron, manganese, cobalt, nickel, copper, zinc, chromium, tungsten, and molybdenum. Oxides containing transition metals can be used, and more preferably carbon nitrides of these transition metal elements and carbon dioxide oxides of these transition metal elements can be used.

Composition formula of the base metal oxide catalysts are, for example, M1C _p N _q O _r (although, M1 is a transition metal element, p, q, r represents the ratio of the number of atoms, 0 ≦ p ≦ 3,0 ≦ q ≦ 2, 0 <r ≦ 3), M2 _a M3 _b C _x N _y O _z (where M2 is zirconium, tantalum, titanium, niobium, vanadium, iron, manganese, cobalt, nickel, copper, It is one metal selected from the group consisting of zinc, chromium, tungsten, and molybdenum, and M3 is at least one metal different from M2 selected from the group. A, b, x, y. , Z represents the ratio of the number of atoms, 0.5 ≦ a <1, 0 <b ≦ 0.5, 0 <x ≦ 3, 0 <y ≦ 2, 0 <z ≦ 3, and a + b = 1. .). Further, a catalyst in which these compounds and a conductive compound are combined can also be preferably used.

(Carbon catalyst)
The carbon catalyst is a carbon catalyst produced by mixing one or more kinds of carbon materials and a compound containing a nitrogen element and a base metal element and performing heat treatment, and conventionally known carbon catalysts can be used. The carbon material used for the carbon catalyst is not particularly limited as long as it is a carbon particle derived from an inorganic material and / or a carbon particle obtained by heat-treating an organic material. Generally, the active points of the carbon catalyst include a base metal element contained in a base metal-N4 structure (a structure in which four nitrogen elements are arranged on a plane centering on the base metal element) on the surface of the carbon particles, and the surface of the carbon particles. Examples thereof include a carbon element in the vicinity of the nitrogen element introduced into the edge portion. Therefore, it is important for the carbon catalyst to contain the nitrogen element and the base metal element constituting the active site in order to have the oxygen reduction activity. Further, the carbon catalyst, BET specific surface area of preferably 20~2000m ² / g, more preferably 40~1000m ² / g, more preferably 60~600m ² / g.

Examples of carbon particles derived from inorganic materials include carbon blacks such as furnace black, acetylene black, ketjen black and medium thermal carbon black;
Examples thereof include activated carbon, graphite, carbon nanotubes, carbon nanofibers, carbon nanohorns, graphene, graphene nanoplatelets, nanoporous carbon and carbon fibers. Carbon particles have various physical properties such as particle size, shape, BET specific surface area, pore volume, pore size, bulk density, DBP oil absorption, surface acid basicity, surface hydrophilicity, and conductivity, depending on the type and manufacturer. Since the costs are different, the optimum material can be selected according to the intended use and required performance. Inorganic carbon particles are used in one type or two or more types.
As the carbon particles derived from the inorganic material, graphene nanoplatelets, carbon black, carbon nanotubes and the like are preferable because it is easy to obtain a carbon catalyst having a large specific surface area and high electron conductivity.

The organic material that becomes carbon particles by heat treatment is not particularly limited as long as it is a material that becomes carbon particles after heat treatment. In order to allow the carbon particles after the heat treatment to contain a hetero element as an active site, it may be preferable to use an organic material containing the hetero element in advance. Specific organic materials include phenol-based resin, polyimide-based resin, polyamide-based resin, polyamideimide-based resin, polyacrylonitrile-based resin, polyaniline-based resin, phenolformaldehyde resin-based resin, polyimidazole-based resin, polypyrrole-based resin, and poly. Examples thereof include benzoimidazole-based resins, melamine-based resins, pitches, brown charcoal, polycarbodiimide, biomass, proteins, fumic acid and the like, and derivatives thereof.

The compound containing a nitrogen element and a base metal element may be a compound containing one or more kinds of nitrogen element and a base metal element, and is not particularly limited as long as it does not deviate from the gist of the present invention. Examples thereof include organic compounds such as dyes and polymers containing metals, and inorganic compounds such as elemental metals, base metal oxides, and metal salts. The compound may be used alone or in combination of two or more. Base metal elements are metal elements excluding noble metal elements (lutenium, rhodium, palladium, silver, osmium, iridium, platinum, gold) among transition metal elements, and base metal elements include cobalt, iron, nickel, manganese, and copper. , Titanium, vanadium, chromium, zinc, tin, aluminum, zirconium, niobium, tantalum, and magnesium.

From the viewpoint of efficiently introducing a nitrogen element or a base metal element into a carbon catalyst, a nitrogen-containing aromatic compound capable of containing the base metal element in the molecule is preferable. Specific examples thereof include phthalocyanine compounds, naphthalocyanine compounds, porphyrin compounds, tetraazaannulene compounds and the like. The aromatic compound may be one into which an electron-withdrawing functional group or an electron-donating functional group has been introduced. In particular, the phthalocyanine compound is particularly preferable as a raw material because compounds containing various base metal elements are available and the cost is low. Specific examples thereof include metal phthalocyanine compounds such as cobalt phthalocyanine compounds, nickel phthalocyanine compounds and iron phthalocyanine compounds. By using these raw materials, it is possible to provide a carbon catalyst that is inexpensive and has high oxygen reduction activity.

The method for producing the carbon catalyst is not particularly limited, and a method of supporting and carbonizing a cyclic organic compound on the surface of a carbon carrier, a method of carbonizing a mixture of a cyclic organic compound and another organic material, and a method of carbonizing an organic material containing no cyclic organic compound. Conventionally known methods such as a method for causing carbonization and a method for using carbon particles derived from an inorganic carbon material can be used. A preferred production method is a method in which carbon particles derived from an inorganic carbon material and a compound containing a nitrogen element and a base metal element are mixed and then heat-treated in an inert gas atmosphere to obtain a carbon catalyst. The heat treatment may be performed in multiple steps at a plurality of temperatures, and may include a step of washing and drying with an acid after or during the heat treatment step.
By using a carbon material, which is a conductive material, and a carbon catalyst in combination, it is possible to exhibit power generation characteristics that cannot be obtained by a conductive material alone, and further reduce costs depending on the application.

<Silicone>
The composition for forming a microbial fuel cell electrode of the present invention is characterized by containing silicone.
Examples of silicone include silicone resin, silicone oil, and silicone rubber.

<Silicone oil>
The silicone oil may contain only one type of silicone oil molecule or a different type of silicone oil molecule. Silicone oil molecules contain elements of silicon, oxygen, carbon and hydrogen.
In the silicone oil molecule, the silicon atom is interconnected with other silicon atoms via 1 to 4 oxygen atoms. Each silicon atom forms four covalent bonds with an oxygen atom or another atom of a methyl group.
Silicone oil molecules can take the form of cyclic, branched or linear forms. Examples of the cyclic silicone oil molecule include decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, tetradecamethylcycloheptasiloxane, and the like. Examples of the linear silicone oil molecule include decamethyltetrasiloxane, dodecamethylpentasiloxane, tetradecamethylhexasiloxane, and hexadecamethylheptasiloxane.
The silicone oil preferably contains a polydimethylsiloxane molecule. The weight average molecular weight of polydimethylsiloxane is preferably 150,000 or less. When the weight average molecular weight exceeds 150,000, the viscosity becomes very high and it is difficult to handle.

<Binder resin>
The binder resin in the present invention is used for binding particles such as conductive carbon, and the effect of dispersing these particles in a solvent is small. However, if either the conductive material or the silicone has a function of binding the particles, the binder resin may not be required.
As the binder resin, conventionally known ones can be used, for example, acrylic resin, polyurethane resin, polyester resin, phenol resin, epoxy resin, phenoxy resin, urea resin, melamine resin, alkyd resin, formaldehyde resin, fluororesin. , Synthetic rubbers such as styrene-butadiene rubber and fluororubber, conductive resins such as polyaniline and polyacetylene, and polymer compounds containing fluorocarbon atoms such as polyvinylidene fluoride, polyvinyl fluoride, perfluorocarbon and tetrafluoroethylene. Further, the binder resin is not limited to these resins, and may be a modified product, a mixture, or a copolymer of these resins. These binder resins may be used alone or in combination of two or more. Of these, acrylic resins and acrylic silicone copolymer resins are preferable.

Further, a resin generally also called water-based resin fine particles can also be used. Aqueous resin fine particles are those in which the binder resin is dispersed in the state of fine particles without being dissolved in an aqueous solvent.
The resin fine particles used are not particularly limited, but are (meth) acrylic emulsion, nitrile emulsion, urethane emulsion, diene emulsion (SBR (styrene butadiene rubber), etc.), fluorine emulsion (PVDF (polyvinylidene fluoride), PTFE). (Polytetrafluoroethylene), etc.) and the like.
The higher the hydrophilicity of the water-based resin fine particles, the greater the effect of water immersion resistance when the mixture ink has a smaller average dispersed particle size.

<Dispersant>
When the electrode-forming composition of the present invention contains a binder resin, it contains a dispersant, if necessary.
The dispersant used in the present invention effectively functions as a dispersant for the conductive material and / or the oxygen reduction catalyst, and can alleviate the aggregation thereof. The dispersant is not particularly limited as long as it has an effect of alleviating aggregation with respect to the conductive material and / or the oxygen reduction catalyst, but an organic solvent-based dispersant and an aqueous dispersant suitable for the solvent contained in the resin composition are used. It is preferable, and two or more kinds may be used. Further, the so-called resin-type dispersant is classified as a binder resin for convenience when it exerts a function of binding particles.

<Organic solvent-based dispersant>
Examples of the organic solvent-based dispersant include a pigment derivative having a basic functional group and a resin having a basic functional group. Further, pigment derivatives having an acidic functional group and resins having an acidic functional group can be mentioned. Among the pigment derivatives having a basic functional group, preferred forms include an organic dye derivative having a basic functional group, an anthraquinone derivative having a basic functional group, an acrydone derivative having a basic functional group, and a basic functional group. Examples include various derivatives such as triazine derivatives. Among the pigment derivatives having an acidic functional group, preferred forms include an organic dye derivative having an acidic functional group, an anthraquinone derivative having an acidic functional group, an acridone derivative having an acidic functional group, and a triazine derivative having an acidic functional group. Examples include various derivatives of.

The method for synthesizing an organic dye derivative having a basic functional group, an anthraquinone derivative having a basic functional group, an acridone derivative having a basic functional group, or a triazine derivative having a basic functional group is not particularly limited. , Well-known methods can be applied. For example, JP-A-54-62227, JP-A-56-118462, JP-A-56-166266, JP-A-60-88185, JP-A-63-305173, JP-A-3. The method described in Japanese Patent Application Laid-Open No. -2676 or Japanese Patent Application Laid-Open No. 11-199796 can be applied. By reference to the disclosure in the above gazette, it is incorporated herein by reference.

The commercially available resin having an acidic functional group is not particularly limited, and examples thereof include the following. These may be used alone or in combination.

Examples of the resin having an acidic functional group manufactured by Big Chemie include Anti-Terra-U, U100, 203, 204, 205, Disperbyk-101, 102, 106, 107, 110, 111, 140, 142, 170, 171 and 174. , 180, 2001, BYK-P104, P104S, P105, 9076, 220S and the like.
Examples of the resin having an acidic functional group manufactured by Lubrizol Japan, Inc. include SOLPERSE3000, 21000, 26000, 36000, 36600, 41000, 41090, 43000, 44000, and 53095.
Examples of the resin having an acidic functional group manufactured by Fuka Additives include EFKA4510, 4530, 5010, 5044, 5244, 5054, 5055, 5063, 5064, 5065, 5066, 5070, and 5071.
Examples of the resin having an acidic functional group manufactured by Ajinomoto Fine-Techno Co., Ltd. include azisper PN411 and azisper PA111.
Examples of the resin having an acidic functional group manufactured by ELEMENTIS include Nuosperse FX-504, 600, 605, FA620, 2008, FA-196, and FA-601.

Examples of the resin having an acidic functional group manufactured by Lion include Polyty A-550 and Polyty PS-1900.
Resins having an acidic functional group manufactured by Kusumoto Kasei Co., Ltd. include Disparon 2150, KS-860, KS-873SN, 1831, 1860, PW-36, DA-1200, DA-703-50, DA-7301, DA-325. , DA-375, DA-234 and the like.
Examples of the resin having an acidic functional group manufactured by BASF Japan Ltd. include JONCRYL67, 678, 586, 611, 680, 682, 683, 690, 52J, 57J, 60J, 61J, 62J, 63J, 70J, HPD-96J, 501J, 354J, 6610, PDX-6102B, 7100, 390, 711, 511, 7001, 741, 450, 840, 74J, HRC-1645J, 734, 852, 7600, 775, 537J, 1535, PDX-7630, 352J, 252D, 538J 7640, 7641, 631, 790, 780, 7610 and the like can be mentioned.
Examples of the resin having an acidic functional group manufactured by Mitsubishi Rayon include Diamond BR-60, 64, 73, 77, 79, 83, 87, 88, 90, 93, 102, 106, 113, and 116. ..

Not limited to the above dispersants, commercially available organic solvent-based dispersants can also be used, and examples thereof include the following.

Dispersants manufactured by Big Chemie include Disperbyk-103, 108, 109, 112, 116, 130, 161, 162, 163, 164, 166, 167, 168, 174, 182, 183, 184, 185, 2000, 2050. , 2070, 2096, 2150, BYK-9077 and the like.
Dispersants manufactured by Nippon Lubrizol include SOLSERSE5000, 9000, 13240, 13650, 13940, 17000, 18000, 19000, 22000, 24000SC, 24000GR28000, 31845, 32000, 32500, 32600, 33500, 34750, 35100, 35200, 37500. , 38500.
Dispersants manufactured by Fuka Additives include EFKA1500, 1501, 1502, 1503, 4008, 4009, 4010, 4015, 4020, 4046, 4047, 4050, 4055, 4060, 4080, 4300, 4330, 4400, 4401, 4402, 4403, 4406, 4520, 4570, 4800, 5207 and the like can be mentioned.

Examples of the dispersant manufactured by Ajinomoto Fine-Techno Co., Ltd. include Azisper PB711, PB821, PB822 and the like.
Examples of the dispersant manufactured by ASP Japan include polyvinylpyrrolidone PVP K-15, K-30, K-60, K-90, K-120 and the like.
Examples of the dispersant manufactured by Kawaken Fine Chemicals Co., Ltd. include Hinoact KF-1000, 1300M, 1500, 1700, T-6000, 8000, 8000E, 9100 and the like.
Dispersants manufactured by Sekisui Chemical Co., Ltd. include Eslek BL-1, Eslek BL-1H, Eslek BL-2, Eslek BL-2H, Eslek BL-5, Eslek BL-10, Eslek BL-S, and Eslek BX-L. , Eslek BM-1, Eslek BM-S, Eslek BH-3, Eslek BX-1, Eslek KS-1, Eslek KS-10, Eslek KS-3 and the like.
Dispersants manufactured by Kuraray include PVA102, PVA103, PVA105, PVA203, PVA403, PVA505, PVA-624, PVA-706, Mobital B16H, Mobital B60HH, Mobital 30T, and Mobital 30H. And so on.

<Aqueous dispersant>
Next, the aqueous dispersant will be described. The aqueous dispersant is not particularly limited, but a cationic dispersant, an anionic dispersant, a nonionic dispersant and the like can be used.
Among the above dispersants, polymer-based resins showing water solubility are preferable, and for example, acrylic resin, polyurethane resin, polyester resin, polyamide resin, polyimide resin, polyallylamine resin, phenol resin, epoxy resin, phenoxy resin, urea resin. , Melamine resin, Alkid resin, Formaldehyde resin, Silicon resin, Fluorine resin, Polymer compounds containing polysaccharide resins such as carboxymethyl cellulose, and in particular, water-soluble by polymerizing or copolymerizing an ethylenically unsaturated monomer. Resin is preferable. Further, as long as it is water-soluble, a modified product, a mixture, or a copolymer of these resins may be used. These dispersants may be used alone or in combination of two or more.
The water-soluble resin referred to in the present invention means that 1 g of the resin is put in 99 g of water at 25 ° C., stirred, left at 25 ° C. for 24 hours, and then the resin can be completely dissolved in water without separation and precipitation. It is a thing.

(Cationic dispersant)
The commercially available cationic dispersant is not particularly limited, and examples thereof include the following.
As cationic dispersants manufactured by Big Chemie, Disperbyk-108, 109, 112, 116, 130, 161, 162, 163, 164, 166, 167, 168, 180, 182, 183, 184, 185, 2000, 2001 , 2050, 2070, 2150, or BYK-9077.
Cationic dispersants manufactured by Nippon Lubrizol include SOLSERSE9000, 13240, 13650, 13940, 17000, 18000, 19000, 20000, 24000SC, 24000GR, 28000, 31845, 32000, 32500, 32600, 33500, 34750, 35100, 35200. , 37500, 38500, or 39000.
Examples of cationic dispersants manufactured by Fuka Additives include EFKA4008, 4009, 4010, 4015, 4020, 4046, 4047, 4050, 4055, 4060, 4080, 4300, 4330, 4400, 4401, 4402, 4403, 4406, Examples thereof include 4500, 4550, 4560, 4570, 4580, or 4800.

Examples of the cationic dispersant manufactured by Ajinomoto Fine-Techno Co., Ltd. include azisper PB711, azisper PB821, and azisper PB822.
Examples of the cationic dispersant manufactured by Kusumoto Kasei Co., Ltd. include Disparon 1850, 1860, or DA-1401.
Examples of the cationic dispersant manufactured by Kyoeisha Chemical Co., Ltd. include Floren DOPA-15B and Floren DOPA-17.

(Anionic dispersant)
The commercially available anionic dispersant is not particularly limited, and examples thereof include the following. These may be used alone or in combination.
Examples of the anionic dispersant manufactured by Big Chemie include Anti-Terra-U, U100, 203, 204, 205, Disperbyk-101, 102, 106, 107, 110, 111, 140, 142, 170, 171 and 174, 180. , 2001, BYK-P104, P104S, P105, 9076, 220S and the like.
Examples of the anionic dispersant manufactured by Lubrizol Japan, Inc. include SOLPERSE3000, 21000, 26000, 36000, 36600, 41000, 41090, 43000, 44000, and 53095. Examples of the anionic dispersant manufactured by Fuka Additives include EFKA4510, 4530, 5010, 5044, 5244, 5054, 5055, 5063, 5064, 5065, 5066, 5070, and 5071.

Examples of the anionic dispersant manufactured by Ajinomoto Fine-Techno Co., Ltd. include azisper PN411 and azisper PA111.
Examples of the anionic dispersant manufactured by ELEMENTIS include Nuosperse FX-504, 600, 605, FA620, 2008, FA-196, FA-601 and the like.
Examples of the anionic dispersant manufactured by Lion include Polyty A-550 and Polity PS-1900.
As anionic dispersants manufactured by Kusumoto Kasei Co., Ltd., Disparon 2150, KS-860, KS-873SN, 1831, 1860, PW-36, DA-1200, DA-703-50, DA-7301, DA-325, DA 375, DA-234 and the like can be mentioned.

Examples of the anionic dispersant manufactured by BASF Japan include JONCRYL67, 678, 586, 611, 680, 682, 683, 690, 52J, 57J, 60J, 61J, 62J, 63J, 70J, HPD-96J, 501J, 354J, 6610, PDX-6102B, 7100, 390, 711, 511, 7001, 741, 450, 840, 74J, HRC-1645J, 734, 852, 7600, 775, 537J, 1535, PDX-7630, 352J, 252D, 538J 7640, 7641, 631, 790, 780, 7610 and the like can be mentioned.
Examples of the anionic dispersant manufactured by Mitsubishi Rayon include Diamond BR-60, 64, 73, 77, 79, 83, 87, 88, 90, 93, 102, 106, 113, and 116.

The commercially available nonionic dispersant is not particularly limited, and examples thereof include the following. These may be used alone or in combination.
Examples of the nonionic dispersant manufactured by Kao Corporation include polyoxyethylene alkyl ethers such as Emulgen 104P and Emulgen 106.
Examples of the nonionic dispersant manufactured by ISP Japan include polyvinylpyrrolidones such as PVP K-15, PVP K-30, PVP K-60, and PVP K-90.

(Molecular weight of dispersant)
The molecular weight of the dispersant used in the present invention is not particularly limited, but is preferably a polymer, and the weight average molecular weight is preferably 1,000 to 2,000,000, more preferably 3,000 to 1,000,000. is there. A dispersant having a small molecular weight such as a surfactant can also be used, but the adsorption rate to the conductive material is low, which may cause an increase in the viscosity of the electrode-forming composition. If the molecular weight is too large, it may cause an increase in viscosity. The weight average molecular weight (Mw) indicates a polystyrene-equivalent molecular weight in gel permeation chromatography (GPC).

<Solvent>
The solvent used in the present invention is not particularly limited and can be used. If necessary, for example, a plurality of solvent types may be mixed and used in order to improve dispersibility and coatability on the support. Solvents include alcohols, glycols, cellosolves, aminoalcohols, amines, ketones, carboxylic acid amides, phosphate amides, sulfoxides, carboxylic acid esters, phosphate esters, ethers, and nitriles. Kind, water, etc. Of these, water and an alcohol solvent having 4 or less carbon atoms are preferable.

<Other additives>
Further, a thickener, a dispersant, a film forming aid, a defoaming agent, a leveling agent, a preservative, a pH adjuster and the like can be added to the mixture ink as needed.
The thickener is not particularly limited, but for example, a low molecular weight compound such as a surfactant, an acrylic resin, a polyurethane resin, a polyester resin, a polyamide resin, a polyimide resin, a polyallylamine resin, a phenol resin, an epoxy resin, or a phenoxy. Examples thereof include polymer compounds containing polysaccharide resins such as resins, urea resins, melamine resins, alkyd resins, formaldehyde resins, fluororesins, and carboxymethyl cellulose. These may be used alone or in combination of two or more.

<Adjustment method of mixture ink>
There are no particular restrictions on the method of preparing the mixture ink. In the preparation, each component may be dispersed at the same time, or the conductive material and / or the oxygen reduction catalyst may be dispersed in an aqueous liquid medium together with the water-soluble resin, and then the binder resin may be added. Alternatively, it can be optimized with an oxygen reduction catalyst, a binder, a dispersant, and a silicone. However, if the catalyst paste composition is prepared first and the binder resin is added afterwards to prepare the mixture ink, it is possible to greatly contribute to cost reduction such as shortening the dispersion time. When silicone is used as a binder, it is preferable to prepare the catalyst paste composition first and then add silicone to prepare the mixture ink. When silicone oil is used, it may be mixed in the catalyst paste composition, or the catalyst paste composition may be prepared first and then added to prepare a mixture ink.
The conductive material and / or the oxygen reduction catalyst is 65 to 98% by mass, preferably 65 to 95% by mass, and more preferably 70 to 90% by mass in the solid content of the mixture ink of the present invention.
Further, in the solid content of the mixture ink of 100% by mass, the silicone is 1 to 20% by mass, preferably 5 to 20% by mass, and more preferably 10 to 20% by mass. By including silicone in the mixture ink, the oxygen supply in the catalyst layer is improved, and good power generation performance can be obtained even when flooded.
When the binder resin is contained, good power generation performance can be obtained by containing 1 to 35% by mass, preferably 5 to 30% by mass, and more preferably 5 to 25% by mass in the solid content of the mixture ink. ..

<Disperser / Mixer>
As an apparatus used for obtaining a mixture ink, a disperser or a mixer usually used for pigment dispersion or the like can be used.
For example, mixers such as disper, homomixer, or planetary mixer; homogenizers such as "Clearmix" manufactured by M-Technique or "Philmix" manufactured by PRIMIX; paint conditioner (manufactured by Red Devil), ball mill, sand mill. (Symmal Enterprises "Dyno Mill" etc.), Atwriter, Pearl Mill (Eirich "DCP Mill" etc.), or media type disperser such as Coball Mill; Wet Jet Mill (Genus "Genus PY", Sugino) Medialess dispersers such as Machine's "Starburst", Nanomizer's "Nanomizer"), M-Technique's "Claire SS-5", or Nara Machinery's "MICROS"; or other roll mills, etc. However, it is not limited to these. Further, as the disperser, it is preferable to use a disperser that has been subjected to metal contamination prevention treatment from the disperser.

For example, when using a media type disperser, a method in which the agitator and the vessel use a disperser made of ceramic or resin, or a disperser in which the surface of the metal agitator and the vessel is treated with tungsten carbide spraying or resin coating. Is preferably used. As the medium, it is preferable to use glass beads, zirconia beads, or ceramic beads such as alumina beads. Also, when using a roll mill, it is preferable to use a ceramic roll. Only one type of dispersion device may be used, or a plurality of types of devices may be used in combination. When the catalyst-supported carbon material is easily cracked or crushed by a strong impact, a medialess disperser such as a roll mill or a homogenizer is preferable to a media type disperser.

<Electrodes for microbial fuel cells>
The configuration of the electrode used in the present invention is not particularly limited. For example, a base material may be subjected to a water-repellent treatment described later, and then the mixture ink of the present invention may be applied to one side to form a catalyst layer.

<Base material>
The electrode for a microbial fuel cell of the present invention (hereinafter, also referred to as an electrode) includes a base material and a layer formed from the electrode-forming composition. The base material includes a conductive base material and a non-conductive base material.

<Conductive substrate>
The conductive base material used in the electrode of the present invention preferably has excellent corrosion resistance and electrical conductivity, a large surface area, and excellent diffusion of reactants and products, and the material and shape are not particularly limited. For example, in addition to carbon materials such as graphite paper, graphite cloth and graphite felt, metal materials such as stainless mesh and platinum mesh can be used, but the present invention is not limited to this. The conductive base material used for the electrode may be water-repellent in advance. For example, the cathode is impregnated with a dispersion of PTFE, dried, and then heated at around 400 ° C. to develop water repellency. Further, the conductive material may be dispersed in the PTFE dispersion liquid. The water repellent treatment is not limited to these.

<Non-conductive base material>
When the layer formed from the composition for forming a microbial fuel cell electrode has sufficient conductivity, the base material used for the electrode may be non-conductive. Examples of the non-conductive base material that can be used for the electrode of the present invention include papers, cloths, resin films, and the like. From the viewpoint of durability, resin films and cloths are particularly preferable.

<Coating method of mixture ink>
The method for applying the mixture ink of the present invention is not particularly limited, and a known method can be used. Examples include a gravure coating method, a spray coating method, a screen printing method, a dip coating method, a die coating method, a roll coating method, a doctor coating method, a knife coating method, a screen printing method or an electrostatic coating method. As the drying method, a stand-alone drying, a blower dryer, a warm air dryer, an infrared heater, a far infrared heater and the like can be used, but the drying method is not particularly limited thereto.

<Microbial fuel cell>
A microbial fuel cell is a battery that promotes the decomposition of organic matter while recovering electrons generated from the metabolic activity in which microorganisms decompose organic matter. Electron-donating microorganisms are retained in the anode, and metabolism is performed using organic substances contained in organic wastewater and soil to generate electrons and protons. At the cathode, the generated electrons and protons are used to perform an oxygen reduction reaction to generate electricity.
The configuration consists of a conductive support that serves as an anode in which electron donating microorganisms are retained and a conductive support that serves as a cathode coated with a catalyst material for fuel cells, and a partition wall in an electrolytic cell containing organic waste water or the like as an electrolytic solution. It may be a one-tank type configuration in which the fuel cell is inserted without being provided, or a two-tank type configuration in which the anode tank and the cathode tank are separated by using a solid polymer membrane, such as a solid polymer fuel cell. Further, not only the electrolytic cell surrounded by a surface but also an unenclosed environment such as a paddy field, a lake, a river, or the sea may be used. For example, a cathode is installed on the liquid surface, side surface, and bottom surface that separates the inside of the electrolytic cell that holds the electrolytic solution from the outside of the electrolytic cell such as the atmosphere containing oxygen, or a cassette type electrode that can take in outside air is placed in the liquid. A form such as immersing in is conceivable. At this time, the catalyst layer of the cathode is in contact with the electrolytic solution, and the back surface thereof is installed so as to be in contact with the atmosphere containing oxygen. As a result, the atmosphere containing oxygen directly flows into the cathode from the outside of the electrolytic cell, and a reaction occurs on the catalyst in the cathode in contact with the electrolytic solution.

The electrolyte used in a microbial fuel cell has proton conductivity and contains a substrate that is oxidatively decomposed by microorganisms. The substrate is not particularly limited as long as it is a substance that can be metabolized by the microorganism that donates electrons. For example, in addition to organic substances such as sugars, proteins and lipids, inorganic substances such as ammonia may be mentioned, and one or more of them may be contained. Therefore, as the electrolytic solution, domestic wastewater, industrial wastewater, etc. that satisfy the above conditions can be used. Further, instead of the electrolytic solution, a solid medium having ionic conductivity such as proton may be used. Examples thereof include commercially available soil, low soil such as ponds, bottom mud, and resin sheets, but the present invention is not particularly limited. Further, a mediator responsible for electron transfer between the microorganism and the anode may be introduced, and examples thereof include methylene blue and neutral red.

The microorganism that donates electrons in the microbial fuel cell may be a single type or a plurality of types as long as it causes an anodic reaction that oxidatively decomposes the substrate to generate electrons. In addition, microorganisms are retained in the electrolytic cell by floating in the electrolytic cell or immobilizing on the anode. The microbial species are not particularly limited, but those belonging to the genus Shewanella and the genus Geobacter can be exemplified.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples do not limit the scope of rights of the present invention at all. In the examples and comparative examples, "parts" represents "parts by mass" and "%" represents "% by mass".

<Oxygen reduction catalyst, carbon catalyst>
[Manufacturing Example 1]
Ketchen Black (manufactured by Lion Specialty Chemicals Co., Ltd.) and iron phthalocyanine (manufactured by Sanyo Dye Co., Ltd.) are weighed at a mass ratio of 1 / 0.5 and dry-mixed with a particle compounding device Mechanofusion (manufactured by Hosokawa Micron). , A mixture was obtained. The above mixture was filled in an alumina crucible and heat-treated in an electric furnace at 800 ° C. for 2 hours in a nitrogen atmosphere to obtain an oxygen reduction catalyst.

<Adjustment of mixture ink>
[Mixed material ink composition 1]
As a catalyst, 5.6 parts of the oxygen reduction catalyst of Production Example 1 and 85.2 parts of a 1: 1 mixed solution of water and 1-propanol as a solvent were put into a mixer and mixed, and further put into a sand mill to disperse. Then, polydimethylsiloxane, trimethylsiloxy terminated, M. et al. W. Add 0.8 parts of 14000 (manufactured by Alfa Aesar) and 3.2 parts (manufactured by Toyochem) of emulsion type acrylic resin dispersion solution W-168 (manufactured by Toyochem) and mix with a disper to obtain a mixture ink. It was.

[Mixed material ink composition 2-11]
Using the catalyst, conductive material, silicone, binder, dispersant, and solvent shown in Table 1, a mixture ink was prepared in the same manner as in the mixture ink composition 1, and the mixture inks 2 to 11 were obtained. The content of each solid content in the mixture ink is shown in Table 1 in mass%.

The materials listed in Table 1 are shown below.
(Conductive material)
・ A-1: Powdered activated carbon (manufactured by Futamura Chemical Co., Ltd.)
・ A-2: MA14 (manufactured by Mitsubishi Chemical Corporation)
(Oxygen reduction catalyst)
・ A-3: TEC10E50E (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.)
-A-4: Carbon catalyst (silicone) of Production Example 1
B-1: Polydimethylsiloxane, trimethylsiloxy terminated, M. et al. W. 14000 (manufactured by Alfa Aesar)
B-2: Polydimethylsiloxane, trimethylsiloxy terminated, M. et al. W. 1250 (manufactured by Alfa Aesar)
B-3: Polydimethylsiloxane, trimethylsiloxy terminated, M. et al. W. 117,000 (manufactured by Alfa Aesar)
・ B-4: KR-5206 (manufactured by Shin-Etsu Chemical Co., Ltd.)
(binder)
-C-1: Emulsion type acrylic resin dispersion solution W-168 (manufactured by Toyochem Co., Ltd.)
・ C-2: Byron 200 (manufactured by Toyobo Co., Ltd., polyester resin)
(Dispersant)
・ CMC Daicel # 1240 (manufactured by Daicel FineChem)

<Manufacturing electrodes for fuel cells>
[Example 1]
The applicator was set so that the gap was 380 μm, and the mixture ink 1 shown in Table 1 was applied to the carbon paper. After coating, it was dried at 110 ° C. to obtain an electrode.

[Examples 2 to 9, Comparative Example 1]
Using the mixture inks 2 to 9 and 11 shown in Table 1, fuel cell electrodes were produced in the same manner as the fuel cell electrodes.

[Example 10]
Using the 10 mixture inks shown in Table 1, fuel cell electrodes were produced in the same manner as the fuel cell electrodes. As the conductive material and / or the oxygen reduction catalyst (A), a mixture of MA14 (manufactured by Mitsubishi Chemical Corporation) and the carbon catalyst of Production Example 1 in equal mass ratios was used.

[Comparative Example 2]
An applicator was set so that the gap was 200 μm, and polydimethylsiloxane, which is a silicone oil, was used as a water-repellent layer on carbon paper. W. A solution prepared by mixing 14000 (manufactured by Alfa Aesar) and 1-propanol at a mass ratio of 1/9 was applied. After coating, the mixture was dried at 110 ° C., the mixture ink 11 was applied to the surface opposite to the coated surface, and the mixture was dried at 110 ° C. to obtain an electrode.

<Fuel cell>
The evaluation using the fuel cell of the present invention was carried out in a one-tank configuration.
In an electrolytic cell having a capacity of 30 mL, a platinum electrode as a counter electrode, an Ag / AgCl electrode as a reference electrode, and electrodes of Examples 1 to 17 and Comparative Examples 1 to 8 as working electrodes were installed on the side surface of the electrolytic cell. As the electrolytic solution, a phosphate buffered saline solution adjusted to 0.1 M was used.

(Power generation test before and after flooding)
A potentio galvanostat (VersaSTAT3, manufactured by Princeton Applied Research) was used to perform current-voltage measurements at room temperature for evaluation.
Then, the prepared fuel cell electrode was _{immersed in a buffer solution of K 2} HPO ₄ / KH ₂ PO ₄ (pH 7.0) for 96 hours, and the current-voltage was again at room temperature using the immersion fuel cell electrode. Measurements were made and evaluated.
As a power generation characteristic, a percentage (%) of the power generation amount per electrode unit area before immersion with respect to the power generation amount per electrode unit area after immersion in a buffer solution of _{K 2} HPO ₄ / KH ₂ PO _{4 (pH 7.0).} ) Was asked.
The judgment criteria are shown below.
⊚: Maintenance rate 95% or more (extremely good)
〇: Maintenance rate 90% or more and less than 95% (good)
〇 △: Maintenance rate 80% or more and less than 90% (no problem in practical use)
Δ: Maintenance rate 60% or more and less than 80% (defective)
×: Maintenance rate less than 60% (extremely defective)

From the results shown in Table 2, those containing silicone showed good power generation performance before and after flooding. In Comparative Example 1 containing no silicone, the water immersion resistance could not be maintained, the catalyst layer was flooded, and the power generation performance was deteriorated. Further, even in Comparative Example 2 in which the catalyst layer and the water-repellent layer are used in combination, the catalyst layer itself cannot be prevented from being flooded, so that the power generation performance is deteriorated.
By using the fuel cell electrode forming composition having the above-mentioned composition, it was possible to reduce the amount of expensive materials and peripheral members used while maintaining the power generation characteristics, and to produce an inexpensive and high-performance electrode forming composition.

(Durability evaluation by microbial fuel cell)
^{After anaerobically culturing a mixed solution of Shewanella oneidenis MR-1 (single culture, 15} cells / mL) and paddy soil as an electron donating microorganism in an electrolytic cell having a capacity of 30 mL at 30 ° C. for 3 days, _{A buffer solution of K 2} HPO ₄ / KH ₂ PO ₄ (pH 7.0) was used as the electrolyte solution, and 2.0 g COD / L / day (COD: chemical oxygen demand) of domestic wastewater containing glucose as a nutritional substrate was applied. Inflowed continuously. A carbon cloth was applied as the conductive support of the negative electrode, and the ink composition of Example 1 was applied to the carbon paper base material (TGP-H-090) as the positive electrode, and the electrode was dried in an air atmosphere at 95 ° C. for 60 minutes. Each was inserted into an electrolytic cell.
When the voltage of the prepared microbial fuel cell device was measured with a tester for one month and the output retention rate after one month was evaluated when the voltage after one week was set to 100%, the maintenance rate was 90% or more. ..
When the measurement was carried out using the ink composition of Comparative Example 1 as the positive electrode by the same method as described above, the maintenance rate was reduced to 80%, and the same tendency as in the power generation test before and after flooding was observed.

Claims (10)

A composition for forming a microbial fuel cell electrode containing a conductive material and / or an oxygen reduction catalyst and silicone. The composition for forming a microbial fuel cell electrode according to claim 1, wherein the silicone is a silicone oil. The composition for forming a microbial fuel cell electrode according to claim 1 or 2, wherein the silicone is polydimethylsiloxane. The composition for forming a microbial fuel cell electrode according to any one of claims 1 to 3, further comprising a binder resin. The composition for forming a microbial fuel cell electrode according to claim 4, wherein the binder resin contains aqueous resin fine particles. The composition for forming a microbial fuel cell electrode according to any one of claims 1 to 5, further comprising a dispersant. The composition for forming a microbial fuel cell electrode according to any one of claims 1 to 6, wherein the oxygen reduction catalyst is one or more selected from the group consisting of a noble metal catalyst, a base metal oxide catalyst, and a carbon catalyst. The composition for forming a microbial fuel cell electrode according to any one of claims 1 to 7, further comprising a solvent. An electrode for a microbial fuel cell comprising a base material and a layer formed from the composition for forming a microbial fuel cell electrode according to any one of claims 1 to 8. A microbial fuel cell comprising the electrode for the microbial fuel cell according to claim 9.