JP7400438B2 - Electrodes for enzyme power generation devices and enzyme power generation devices - Google Patents

Description

The present invention relates to an electrode for an enzyme power generation device and an enzyme power generation device.

Enzyme power generation devices currently under development are power generation devices that use organic substances such as sugar, alcohol, and organic acids as fuel and utilize the electrical energy of electrons generated through enzymatic reactions.
In recent years, in addition to using the electrical energy extracted from enzyme power generation devices as a power source, a method has also been proposed that utilizes the substrate selectivity of enzymes to use them as self-power-generating sensors for sensing organic substances such as sugars and alcohols. has been done. Self-power generation sensors have both power generation and organic matter sensing functions, so they are smaller, lighter, and less expensive because they do not require a power source.They also feature high sensing accuracy due to minute amount detection using enzymes and high substrate selectivity. becomes. Therefore, it is expected to be used as a power source for sensors used in wearable devices and implant devices for living organisms.
On the other hand, enzyme power generation devices contain redox enzymes in the negative and positive electrodes, and are energy systems that generate electricity using various organic substances and oxygen in the air as fuel. Although it has several advantages such as high safety, there are also issues regarding output stability, lifespan, cost, etc.

Various measures have been taken so far to solve the above problems. For example, to improve power generation performance, a porous enzyme fuel cell using porous carbon (Patent Document 1) and an electrode using a hydrophilic binder that is insoluble in water are created to improve the penetration of enzyme solution. (Patent Document 2), and a method of providing a protective film between the electrode and the electrolyte membrane in order to alleviate the deactivation of the enzyme due to contact with the acidic group of the electrolyte, in order to extend the life of the enzyme (Patent Document 3) , a method of suppressing enzyme elution using a photocurable resin (Patent Document 4), etc. have been reported. However, it cannot be said that the performance and stability are low, the applications are limited, etc., and it is difficult to say that the problems related to power generation performance have been solved at present.

Japanese Patent Application Publication No. 2009-181889 International Publication No. 2013/065581 Japanese Patent Application Publication No. 2015-109188 Patent No. 5181576

An object of the present invention is to provide an electrode for an enzyme power generation device that constitutes an enzyme power generation device. By using the electrode for an enzyme power generation device of the present invention, it is possible to provide an enzyme power generation device with excellent power generation performance.

The present inventor has found that the above-mentioned problems can be solved in an electrode for an enzyme power generation device that contains at least a conductive material and a resin material and has a hydrophilicity of 0.15 to 1.0, and has arrived at the present invention. .

That is, the present invention relates to an electrode for an enzyme power generation device that contains at least a conductive material and a resin material and has a hydrophilicity of 0.15 to 1.0.

The present invention also relates to the electrode for an enzyme power generation device, wherein the resin material includes a water-soluble resin.

The present invention also relates to the electrode for the enzyme power generation device, wherein the water-soluble resin includes at least one water-soluble resin selected from the group consisting of polyvinylpyrrolidone, polyvinyl alcohol, polystyrene sulfonic acid, polyacrylic acid, and carboxymethylcellulose.

The present invention also relates to the electrode for the enzyme power generation device, wherein the conductive material includes a conductive carbon material.

The present invention also relates to the electrode for the enzyme power generation device, wherein the conductive carbon material includes at least one conductive carbon material selected from the group consisting of carbon black, graphene-based carbon materials, carbon nanotubes, and graphite.

The present invention also relates to the electrode for the enzyme power generation device, wherein the conductive carbon material includes an oxidized conductive carbon material.

The present invention further relates to the electrode for the enzyme power generation device containing an oxidoreductase.

The present invention also relates to an enzyme power generation device comprising the enzyme power generation device electrode.

The present invention also relates to the enzyme power generation device, in which the fuel and/or the sensing object includes at least one selected from the group consisting of glucose, lactic acid, and fructose.

An object of the present invention is to provide an electrode for an enzyme power generation device that constitutes an enzyme power generation device, and an enzyme power generation device using the same. By using the electrode for an enzyme power generation device of the present invention, it is possible to provide an enzyme power generation device equipped with the electrode and having excellent power generation performance.

The present invention will be explained in detail below. In addition, in this specification, "resin" may be referred to as "polymer." Further, the "electrode for enzyme power generation device" may be simply referred to as "electrode." Moreover, the "electrode composition for an enzyme power generation device" may be simply referred to as a "composition."

<Electrode for enzyme power generation device>
The electrode for an enzyme power generation device includes at least a conductive material and a resin material. The electrode for an enzyme power generation device of the present invention can be prepared by directly applying an electrode composition for an enzyme power generation device (described later) to a base material such as a conductive support (such as carbon paper or a conductive layer to be described later) or a separator and drying it, or It is produced by applying the composition to a material and drying it to form a coating film, and then transferring it to the conductive support, separator, etc.
The method for applying the composition is not particularly limited, and examples include general methods such as knife coater, bar coater, blade coater, spray, dip coater, spin coater, roll coater, die coater, curtain coater, and screen printing. methods can be applied.

The electrode for an enzyme power generation device of the present invention may contain an enzyme or a mediator if necessary. As for the method of supporting enzymes and mediators, enzymes and mediators may be included in the electrode composition for an enzyme power generation device, which will be described later, or may be supported on a coating film that has been dried after application. If it is carried out later, a method can be used in which the coating film is immersed in a solution in which the enzyme or mediator is dissolved, and then dried and supported.
Electrodes for enzyme power generation devices may be prepared by using a coating film prepared from an enzyme-containing electrode composition for enzyme power generation devices as is, or by further supporting an enzyme on a coating film prepared from an enzyme-containing electrode composition for enzyme power generation devices. The coating film prepared from the electrode composition for enzyme power generation devices that does not contain enzymes can be used as an enzyme, or the coating film prepared from the electrode composition for enzyme power generation devices that does not contain enzymes can be used as is. It is used as a negative electrode for an enzyme power generation device and a positive electrode for an enzyme power generation device, which will be described later.

In the electrode for an enzyme power generation device of the present invention, an enzyme redox reaction occurs in the electrode. Reactions progress by efficiently transporting the electrons, ions, fuel, etc. necessary for enzymatic reactions. Therefore, in the electrode for an enzyme power generation device of the present invention, it is preferable that the specific surface area is large and the electrical conductivity is high. The larger the specific surface area, the more reaction sites with electrons, protons, fuel, oxygen, etc., which is preferable. Further, the higher the conductivity, the more electrons necessary for the redox reaction in the electrode can be supplied to enzymes and mediators, which is more likely to lead to an increase in current, which is preferable.

The electrode for an enzyme power generation device in the present invention has a surface hydrophilicity represented by the ratio (BET _H2O /BET _N2 ) of the BET specific surface area with water as an adsorbent (BET _H2O ) and the specific surface area with nitrogen as an adsorbent (BET _N2 ). A range of 0.15 to 1.0 is preferable because it is advantageous for the transmission of ions and fuel in the electrode. If the hydrophilicity is 0.15 or more, it will be advantageous for the transfer of ions and fuel in the electrode, making it easier for the enzyme reaction to proceed efficiently. On the other hand, if it exceeds 1.0, the affinity of the electrode surface for the electrolyte etc. will be excessive. If the temperature increases, the supported materials (enzymes, mediators, resins, etc.) may easily dissolve into the electrolyte and the like.
The hydrophilicity is more preferably 0.2 to 0.9, still more preferably 0.2 to 0.7.

Examples of means for controlling the hydrophilicity of the electrode for an enzyme power generation device in the present invention include the following. To improve the hydrophilicity, hydrophilic treatments for electrodes include oxidation treatment by heating, plasma treatment, UV-ozone treatment, surface coating with hydrophilic materials, etc. Hydrophilic treatments for electrode compositions include: Examples include adding highly hydrophilic water-soluble resins and surfactants, and using surface-treated conductive materials. These methods may be used alone or in combination of two or more. In addition, examples of reducing the degree of hydrophilicity include surface coating or addition of a water-repellent material such as a fluorine-based material to the electrode.

<Conductive material>
Next, the conductive material will be explained. The conductive material is contained in order to increase the electron conductivity at the electrode and facilitate the progress of the oxidation-reduction reaction. Although conductive carbon materials are mainly mentioned here, the material is not limited to this. The conductive carbon material that is the conductive material used in the present invention is not particularly limited as long as it has conductivity, but includes carbon black (furnace black, acetylene black, Ketjen black, medium thermal carbon black). ), activated carbon, graphite, carbon nanotubes, carbon nanofibers, carbon nanohorns, graphene-based carbon materials (graphene, graphene nanoplatelets, etc.), nanoporous carbon, carbon fibers, etc. can be used alone or in combination of two or more types. . Among the above, carbon black, graphene-based carbon materials, carbon nanotubes, and graphite are preferable because they have high conductivity and specific surface area, and are advantageous for proceeding with the redox reaction.

Carbon black is produced by continuously pyrolyzing gaseous or liquid raw materials in a reactor, especially Ketjen black made from ethylene heavy oil, which burns the raw material gas and uses the flame to pass through the bottom of the channel steel. Various types of black, such as channel black precipitated by quenching and precipitating, thermal black obtained by periodically repeating combustion and thermal decomposition using gas as a raw material, and acetylene black made from acetylene gas in particular, can be used alone or in combination. More than one type can be used in combination. Further, commonly used oxidized carbon black, hollow carbon, etc. can also be used.

The larger the specific surface area of the carbon black used, the more contact points between carbon black particles, which is advantageous for lowering the internal resistance of the electrode, and the more effective it is because the amount of enzyme supported on the carbon surface increases. It is. Specifically, the specific surface area (BET) determined from the amount of nitrogen adsorption is 20 m ² /g or more and 1500 m ² /g or less, preferably 50 m ² /g or more and 1500 m ² /g or less, more preferably 100 m ² It is desirable to use one with a surface area of 1,500 m ² /g or more and 1,500 m 2 /g or less.

The conductive carbon material may have its surface subjected to oxidation treatment in order to increase its hydrophilicity. Examples of oxidation treatment methods include gas phase oxidation treatment using air, ozone, nitrogen oxide, etc., and chemical oxidation treatment using oxidizing acids, hydrogen peroxide, potassium permanganate, and the like.

Commercially available conductive carbon materials include, for example,
Ketjen Black manufactured by Lion Specialty Chemicals such as Ketjen Black EC-300J, EC-600JD, Lionite EC-200L;
Furnace black manufactured by Tokai Carbon Co., Ltd. such as Toka Black #4300, #4400, #4500, and #5500;
Furnace black manufactured by Degussa such as Printex L;
Furnace black manufactured by Columbian such as Raven7000, 5750, 5250, 5000ULTRAIII, 5000ULTRA, Conductex SC ULTRA, 975 ULTRA, PUER BLACK100, 115, and 205;
Carbon black manufactured by Mitsubishi Chemical Corporation such as #2350, #2400B, #2600B, #3050B, #3030B, #3230B, #3350B, #3400B, #5400B, MA14, MA77, MA7, and MA100;
Cabot furnace blacks such as MONARCH1400, 1300, 900, VulcanXC-72R, and BlackPearls2000;
Furnace black manufactured by TIMCAL such as Ensaco250G, Ensaco260G, Ensaco350G, and SuperP-Li;
Acetylene black manufactured by Denka, such as Denka Black, Denka Black HS-100, and FX-35;
Showa Denko carbon nanotubes such as VGCF, VGCF-H, VGCF-X;
Carbon nanotubes manufactured by Meijo Nano Carbon;
xGnP-C-300, xGnP-C-500, xGnP-C-750, xGnP-M-5, xGnP-M-15, xGnP-M-25, xGnP-H-5, xGnP-H-15, and xGnP - Graphene nanoplatelets manufactured by XG Sciences, such as H-25;
Nanoporous carbon manufactured by Easy-N;
Carbon fiber manufactured by Gunei Chemical Industry Co., Ltd., such as Kynor carbon fiber and Kynor activated carbon fiber;
Knobel manufactured by Toyo Tanso Co., Ltd., such as Knobel MH grade, Knobel MJ (4) 150 grade, Knobel MJ (4) 030 grade, and Knobel MJ (4) 010 grade;
Examples include, but are not limited to, graphite manufactured by Nippon Graphite Co., Ltd. such as FB-100, FB-150, CB-150, CGB-20, CGB-50, LEP, EC300, CMX-60, and UP-20. It is not limited to one type, and two or more types may be used in combination.

<Resin material>
Resin materials are used for purposes such as controlling hydrophilicity in electrodes for enzyme power generation devices, dispersing conductive materials, and binding between particles (binder). In order to control the degree of hydrophilicity, the use of water-soluble resins is preferred. This is because the use of a water-soluble resin makes the electrode hydrophilic, making it easy to control the degree of hydrophilicity to an appropriate level.

<Water-soluble resin>
The water-soluble resin in the present invention is a resin that is soluble in water, and is used for controlling the degree of hydrophilicity in an electrode for an enzyme power generation device. Examples of water-soluble resins include polyvinyl resins, polyurethane resins, polyester resins, polyether resins, cellulose resins such as carboxymethyl cellulose, formalin condensates, silicone resins, and composite polymers thereof. Furthermore, two or more types of these water-soluble resins may be used in combination. Preferred are polyvinylpyrrolidone, polyvinyl alcohol, polystyrene sulfonic acid, polyacrylic acid, carboxymethylcellulose, and the like.

<Binder>
The binder in the present invention is used to bind particles such as a conductive material of an electrode for an enzyme power generation device.
As the binder, conventionally known binders can be used, such as acrylic resin, polyurethane resin, polyester resin, phenol resin, epoxy resin, phenoxy resin, urea resin, melamine resin, alkyd resin, formaldehyde resin, silicone resin, Examples include fluororesins, synthetic rubbers such as styrene-butadiene rubber and fluororubber, conductive resins such as polyaniline and polyacetylene, and polymeric compounds containing fluorine atoms such as polyvinylidene fluoride, polyvinyl fluoride, perfluorocarbon and tetrafluoroethylene. It will be done. Also, modified products, mixtures, or copolymers of these resins may be used. These binders can also be used singly or in combination.

Furthermore, when a mixed solvent of water and a solvent compatible with water is used, a binder, which is generally also called an aqueous emulsion, can also be used. An aqueous emulsion is one in which the binder resin does not dissolve in water but is dispersed in the form of fine particles.

The emulsions used are not particularly limited, but include (meth)acrylic emulsions, nitrile emulsions, urethane emulsions, diene emulsions (SBR (styrene butadiene rubber), etc.), fluorine emulsions (PVDF (polyvinylidene fluoride), PTFE ( polytetrafluoroethylene), etc.).

<Enzyme>
The enzyme in the present invention is not particularly limited as long as it is an enzyme (oxidoreductase) that can give and receive electrons through reaction, and is appropriately selected depending on the fuel to be supplied, cost, type of device, etc.
As the oxidoreductase, enzymes that can catalyze many oxidation-reduction reactions in living bodies, such as substance metabolism, are preferable.
In the negative electrode used in the enzyme power generation device of the present invention, any enzyme capable of emitting electrons may be used, and oxidases and dehydrogenases of sugars, organic acids, etc. can be used. Among these, glucose oxidase is preferable because it is cheaper and more stable than other enzymes, and can use glucose contained in biological samples such as human blood and urine as fuel. Other enzymes include lactate oxidase and lactate dehydegenase, which can use lactic acid in sweat and blood, and fructose oxidase and fructose dehydrogenase, which can use fructose as fuel.
In addition, in the positive electrode used in the enzyme power generation device of the present invention, any enzyme that can consume electrons may be used, such as a type of reductase such as bilirubin oxidase, laccase, or ascorbate oxidase, which catalyzes the reduction of molecular oxygen. Enzymes can be used.

<Mediator>
Depending on the type of enzyme, there are direct electron transfer (DET) enzymes that can directly transfer electrons to the electrode and enzymes that cannot directly transfer electrons. Enzymes other than the DET type can be used in combination with a mediator that plays the role of transferring electrons generated by oxidation of fuel from the enzyme to the electrode (negative electrode) or transferring electrons received from the negative electrode from the electrode (positive electrode) to the enzyme. preferable. The mediator is not particularly limited as long as it is a redox substance that can transfer electrons to and from the electrode, and conventionally known mediators can be used.
Methods for using the mediator include a method in which it is supported on an electrode, a method in which it is dissolved in an electrolytic solution, and the like. Examples of the mediator include tetrathiafulvalene, quinones such as hydroquinone and 1,4-naphthoquinone, ferrocene, ferricyanide, osmium complexes, and polymers modified with these compounds. Non-metallic compounds are preferred from the viewpoint of separation and disposal.

<Conductive support>
The conductive support is not particularly limited as long as it is a material that has conductivity. A conductive layer made of conductive carbon material, carbon paper, carbon felt, carbon cloth, metal foil, metal mesh, etc. are used. The conductive layer is produced by applying a paste containing a conductive carbon material to a base material.

<Electrode composition for enzyme power generation device>
The electrode composition for an enzyme power generation device contains a conductive material, a resin material, and a liquid medium as necessary, and is used to produce an electrode for an enzyme power generation device.

Further, the electrode composition for an enzyme power generation device contains a dispersant and a binder as necessary. The ratio of the conductive material and liquid medium to the binder, dispersant, etc. is not particularly limited and can be appropriately selected within a wide range.

<Liquid medium>
The liquid medium used in the present invention is not particularly limited and can be used. Among these, it is preferable to use water and an aqueous liquid medium that is compatible with water. Liquid media that are compatible with water include alcohols, glycols, cellosolves, amino alcohols, amines, ketones, carboxylic acid amides, phosphoric acid amides, sulfoxides, carboxylic acid esters, and phosphoric acid esters. ethers, nitriles, etc., and may be used within a range that is compatible with water. As alcohols, for example, monohydric alcohols or polyhydric alcohols having a boiling point of about 80 to 200° C. can be used, and alcohol solvents having preferably 4 or less carbon atoms can be used. Specific examples include 1-propanol, 2-propanol, 1-butanol, 2-butanol, and t-butanol. Among these monohydric alcohols, 2-propanol, 1-butanol and t-butanol are preferred. Specifically, the polyhydric alcohol is preferably propylene glycol, ethylene glycol, etc., with propylene glycol being particularly preferred. It is preferable to use water as the liquid medium, and the liquid medium may partially contain a liquid medium that is compatible with water.

<Dispersant>
The dispersant used in the present invention effectively functions as a dispersant for particles such as a conductive material and can alleviate agglomeration thereof. The dispersant is not particularly limited as long as it can have the effect of alleviating aggregation of particles such as the conductive material.

As the dispersant, conventionally known ones can be used. For example, in the case of a resin-type dispersant, one or more resins selected from the group consisting of resins with basic functional groups, resins with acidic functional groups, resins with basic functional groups and acidic functional groups, and nonionic resins are used. Certain dispersants can be used.

Examples of resins with basic functional groups include amino groups containing cyclic structures, skeletons in which part or all of the amino groups are neutralized, and quaternary ammonium salts, such as dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, etc. , methylethylaminoethyl (meth)acrylate, dimethylaminostyrene, diethylaminostyrene, etc., homopolymers of polymerizable monomers, copolymers with other polymerizable monomers, and acid neutralized products thereof. It will be done. (Meth)acrylate means methacrylate or acrylate.

Examples of resins having acidic functional groups include carboxyl groups, sulfo groups, phosphoric acid groups, and skeletons in which these groups are partially or completely neutralized, such as maleic acid, fumaric acid, acrylic acid, methacrylic acid, cinnamic acid, etc. Polymerizable monomers having a carboxyl group, polymerizable monomers having a sulfo group such as vinyl sulfonic acid, (meth)allylsulfonic acid, styrene sulfonic acid, mono(2-acryloyloxyethyl) acid phosphate, mono Examples include homopolymers of polymerizable monomers having a phosphoric acid group such as (2-methacryloyloxyethyl) acid phosphate, copolymers with other polymerizable monomers, and alkali neutralized products thereof.

The resin having a basic functional group and an acidic functional group refers to a resin containing both the basic skeleton and the acidic skeleton, and includes a copolymer of styrene-maleic acid-N,N-dimethylaminoethyl (meth)acrylate. Examples include things.

The nonionic resin is a resin other than the resin having a basic functional group, the resin having an acidic functional group, the resin having a basic functional group and an acidic functional group, and includes polyvinylpyrrolidone, polyvinyl alcohol, polyacrylamide, poly-N - Vinyl acetamide, polyalkylene glycol, etc.

When an electrode for an enzyme power generation device is made from an electrode composition using a water-soluble resin-type dispersant as a dispersant, the inside of the electrode becomes more hydrophilic than a water-insoluble resin-type dispersant, which facilitates the supply of protons to active sites. This is preferred because it is advantageous.

Examples of the water-soluble resin type dispersant include polyvinyl resin, polyurethane type, polyester type, polyether type, cellulose resin such as carboxymethyl cellulose, formalin condensate, silicone type, and composite polymers thereof. Furthermore, two or more types of these water-soluble resin type dispersants may be used in combination. Preferred are polyvinylpyrrolidone, polyvinyl alcohol, polystyrene sulfonic acid, polyacrylic acid, carboxymethylcellulose, and the like.

Examples of commercially available water-soluble resin type dispersants include DISPERBYK-180, 184, 187, 190, 191, 192, 193, 194, 199, 2010, 2012, 2015, 2096 (manufactured by BYK Chemie), SOLSPERSE20000, 27000, etc. , 40000, 41090, 44000, 46000, 47000, 64000, 65000, 66000, etc. (manufactured by Japan Lubrizol), Floren G-700AMP, G-700DMEA, WK-13E, GW-1500, GW-1640, etc. (manufactured by Kyoeisha Chemical Co., Ltd.) ), Borchi (registered trademark) Gen1350, 0851, 1253, SN95, WNS, etc. (manufactured by Matsuo Sangyo Co., Ltd.), TEGO Dispers650, 651, 652, 655, 660C, 715W, 740W, 750W, 752W, 755W, 760W, etc. (manufactured by Tomoe Sangyo Co., Ltd.), etc. ), polyvinylpyrrolidone PVP-K30, K85, K90, etc. (manufactured by ISP Japan), S-LEC BL-1, BL-2, BL-5, BL-10, BL-1H, BL-2H, BL-S, BM-S, BM-1, BM-2, BM-5, BX-1, BX-5, etc. (manufactured by Sekisui Chemical Co., Ltd.), carboxymethylcellulose CMC1110, 1130, 1140, 1170, 1190, 1210, 1240, 1250, etc. (manufactured by Daicel Chemical Industries, Ltd.), but is not limited to these.

In addition, the mass average molecular weight of the water-soluble resin type dispersant is 1000 or more and less than 500000, preferably 5000 or more and less than 400000, and more preferably, from the viewpoint of good dispersibility of the carbon catalyst (A). It is 10,000 or more and less than 200,000.

<Dispersing machine/mixing machine>
As the apparatus used to obtain the composition of the present invention, a dispersing machine and a mixer commonly used for pigment dispersion etc. can be used.

For example, mixers such as a disper, homomixer, or planetary mixer; homogenizers such as "Clearmix" manufactured by M Techniques or "Filmix" manufactured by PRIMIX; paint shakers (manufactured by Red Devil), ball mills, and sand mills. (such as "Dyno Mill" manufactured by Shinmaru Enterprises Co., Ltd.), attritor, pearl mill ("DCP Mill" manufactured by Eirich Co., Ltd., etc.), or media-type dispersion machines such as Koboru Mill; Wet jet mill ("Zinus PY" manufactured by Genus Corporation, Sugino Medialess dispersion machines such as "Starburst" manufactured by Machine Co., "Nanomizer" manufactured by Nanomizer Co., Ltd.), "Clair SS-5" manufactured by M Technique Co., Ltd., or "MICROS" manufactured by Nara Kikai Co., Ltd.; or other roll mills, etc. These include, but are not limited to. Furthermore, it is preferable to use a dispersing machine that has been treated to prevent metal contamination from the dispersing machine.

For example, when using a media-type dispersion machine, the agitator and vessel are made of ceramic or resin, or the surface of the metal agitator and vessel is treated with tungsten carbide spraying or resin coating. It is preferable to use As the media, 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 ceramic rolls. Only one type of dispersion device may be used, or a plurality of types of devices may be used in combination.

<Negative electrode for enzyme power generation device>
In the negative electrode for the enzyme power generation device, electrons generated by the oxidation reaction of the fuel are supplied to the positive electrode.
The negative electrode for an enzyme power generation device includes an electrode for an enzyme power generation device of the present invention containing an oxidase, or an electrode in which an oxidase is directly coated on a conductive support (such as carbon paper or a conductive layer) or a base material such as a separator. used.

<Cathode for enzyme power generation device>
The positive electrode for an enzyme power generation device of the present invention receives electrons generated at the negative electrode and consumes them through a reduction reaction in the electrode. For example, in the case of an oxygen reduction reaction that uses oxygen as an electron acceptor, the structure of the positive electrode for an enzyme power generation device ensures a conduction path for electrons and protons as well as a supply path for oxygen to the active site that serves as the reaction site. This is preferable for efficient power generation.
The positive electrode for an enzyme power generation device is an electrode for an enzyme power generation device of the present invention that contains a reductase, an electrode for an enzyme power generation device of the present invention that does not contain a reductase, or an electrode for an enzyme power generation device of the present invention that contains a reductase and a conductive support (such as carbon paper or a conductive layer). An electrode coated directly on a base material such as or a separator, an electrode for an enzyme power generation device of the present invention made of an oxygen reduction catalyst that does not contain a reducing enzyme, and the like are used.

<Oxygen reduction catalyst>
Examples of oxygen reduction catalysts include non-platinum carbon catalysts, noble metal catalysts, base metal oxide catalysts, activated carbon, and oxygen reductases.

Non-platinum-based carbon catalysts (hereinafter also simply referred to as carbon catalysts) are made of carbon materials with a basic skeleton of carbon elements, and have physical and chemical interactions (bonds) between their constituent units. It is a catalytic material that contains different elements such as heteroatoms such as N, B, and P, and optionally also contains a base metal element and has oxygen reduction activity. The base metal elements here refer to transition metal elements other than noble metal elements (ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, and gold), and base metal elements include cobalt, iron, nickel, It is preferable to contain one or more selected from the group consisting of manganese, copper, titanium, vanadium, chromium, zinc, and tin.
Containing a hetero element and a base metal element has an important meaning in terms of having oxygen reduction activity. Non-platinum-based carbon catalysts use, as their catalytic active sites, nitrogen atoms introduced into the edges of the hexagonal mesh plane of carbon that constitutes the basic skeleton of the carbon material, carbon atoms in the vicinity, and base metals on the catalyst surface. Examples include nitrogen atoms and base metal atoms in a base metal-N4 structure in which four nitrogen atoms are arranged in a plane around an element.
A non-platinum-based carbon catalyst is a carbon catalyst prepared by mixing one or more carbon materials with a compound containing a nitrogen element and/or the base metal element, and subjecting the mixture to heat treatment, and is a conventionally known carbon catalyst. You can use the following. The carbon material used in the carbon catalyst is not particularly limited as long as it is carbon particles derived from an inorganic material and/or carbon particles obtained by heat treating an organic material.

A noble metal catalyst is a catalyst containing one or more noble metals. These noble metal catalysts may be used alone or supported on other elements or compounds.

The base metal oxide catalyst is an oxidation catalyst containing at least one base metal element selected from the group consisting of zirconium, tantalum, titanium, niobium, vanadium, iron, manganese, cobalt, nickel, copper, zinc, chromium, tungsten, and molybdenum. More preferably, carbonitrides of these base metal elements and carbonitrides of these transition metal elements can be used.

Activated carbon is a carbon material synthesized by activation treatment using non-graphitizable carbon materials such as coconut shells and petroleum-based pitch as raw materials, and generally has pores with a diameter of 2 nm or less and a size of 1000 m ² / It has a specific surface area of more than g. Since activated carbon has different physical properties depending on the type and conditions of activation treatment, an activation method suitable for synthesizing the desired activated carbon is appropriately used depending on the conditions and purpose of use.

<Enzyme power generation device>
Enzyme power generation devices are power generation devices that contain enzymes in at least one of the negative and positive electrodes, and utilize enzyme reactions to generate electrons and ions at the negative electrode using various organic substances such as sugar, alcohol, and organic acids as fuel. This is a power generation device that can generate electricity by utilizing the oxygen reduction reaction on the positive electrode side. It can also be used as a sensor for detecting organic substances that serve as fuel by detecting the presence or absence of power generation and the amount of power generation, or by detecting the electrical signal generated by the redox reaction at either the negative or positive electrode. becomes.
Furthermore, by driving the sensor using the electric power generated by the enzyme reaction, it can be used as a power-free sensor (self-generating sensor) that does not require an external power supply. This self-power generation sensor is included in a type of enzyme power generation device, and is expected to be used as a power source for enzyme power generation devices, as well as wearable and implant sensors for living organisms. When used as these biological devices, blood sugar in blood, urinary sugar in urine, sugar and lactic acid in sweat, sugar in tears and saliva, etc. are used as fuel and/or sensing targets. In addition, even if the biological sample does not contain organic substances that can be used as fuel, it is possible to generate electricity using liquid components such as water by incorporating organic substances that can be used as fuel into the battery in advance, and by sensing the liquid components. It can also be used as an object sensor (for example, a moisture sensor).

<Separator>
The separator is not particularly limited as long as it can electrically separate the negative electrode and the positive electrode (preventing short circuits), and conventionally known materials can be used. Specifically, polyethylene fibers, polypropylene fibers, glass fibers, resin nonwoven fabrics, glass nonwoven fabrics, felt, filter paper, Japanese paper, etc. can be used.
Further, in order to improve retention of liquid components and ionic conductivity, a water-absorbing polymer may be used alone or in combination with the separator. Examples of water-absorbing polymers include hydrophilic polymer materials made of polysaccharides such as polyacrylates and carboxymethyl cellulose.

<Fuel>
The fuel that can be used in the enzyme power generation device of the present invention is not particularly limited as long as it can be decomposed by enzymes, and includes monosaccharides such as D-glucose, polysaccharides such as starch, alcohols such as ethanol, and organic acids. It can be used in a wide variety of ways as long as it is organic. In particular, glucose, lactic acid, fructose, etc. can be preferably used because of their high reactivity and their abundance in biological samples.

<Ionic conductor>
The ion conductor in the present invention conducts ions between an anode and a cathode. The form of the ion conductor is not particularly limited as long as it has ion conductivity. As the ion conductor, an electrolytic solution in which an electrolyte such as a phosphate or a sodium salt is dissolved, or a solid polymer electrolyte may be used.

<Sensing of enzyme power generation device>
By using the enzyme power generation device of the present invention, it is possible to sense organic substances that can be used as fuel, such as organic substances sensors for various organic substances, biological samples such as blood, sweat, urine, feces, tears, saliva, and exhaled breath. Biological sensors that target organic matter and body fluids, food sensors that target sugars in fruits and foods, IoT sensors, environmental sensors that target organic matter in the environment such as the atmosphere, rivers, and soil, animals and insects. , animal and plant sensors targeting plants, etc. Among these, biological sensors include, for example, blood sugar level sensors that detect glucose in the blood, urine sugar level sensors that detect sugar in urine, and lactic acid level sensors that detect lactic acid levels in sweat. Examples include fatigue level sensors and heat stroke sensors that sense the level of fatigue.As food sensors, for example, they can be usefully used in fruit sensors that target fructose.
In addition, the devices used for sensing the enzyme power generation device include a bipolar type that uses the electrode for the enzyme power generation device of the present invention as a positive electrode and/or a negative electrode, and a general device that uses the electrode for the enzyme power generation device of the present invention as a negative electrode and combines a reference electrode and a counter electrode. It can be used in a three-electrode configuration such as a typical biosensor configuration.

EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the following Examples do not limit the scope of the present invention in any way. In addition, "part" in Examples and Comparative Examples represents "part by mass", and "%" represents "% by mass".

<Manufacture of enzyme power generation device electrode composition>
[Manufacture example 1]
6 parts of carbon black (Lionite EC-200L, manufactured by Lion Specialty Chemicals) as a conductive carbon material, 89.8 parts of water as a solvent, and polyvinylpyrrolidone (manufactured by Fuji Film Wako Pure Chemicals, Inc.) as a water-based resin. 3 parts of K-30) were placed in a sand mill and dispersed. Thereafter, 2.4 parts (solid content: 50%) of an emulsion-type acrylic resin dispersion solution (manufactured by Toyochem Co., Ltd.: W-168) was added as a binder and mixed with a mixer to obtain an electrode composition (1) for an enzyme power generation device.

[Production Examples 2 to 5]
Electrode compositions (2) to (5) for enzyme power generation devices were prepared using the formulation shown in Table 1 in the same manner as in Production Example 1.

導電性炭素材料
・ＥＣ－２００Ｌ：カーボンブラック（ライオン・スペシャリティ・ケミカルズ社製：ライオナイトＥＣ－２００Ｌ）
・ＭＡ１４：酸化カーボンブラック（三菱ケミカル社製：ＭＡ１４）
水性樹脂
・ＰＶＰ：ポリビニルピロリドン（富士フィルム和光純薬社製：Ｋ－３０）
バインダー
・Ｗ－１６８：エマルション型アクリル樹脂分散溶液（トーヨーケム社製：Ｗ-１６８）
・ＰＶＤＦ：ＫＦポリマー（クレハ社製：＃９１００）
溶剤
・ＮＭＰ：Ｎ－メチルピロリドン

Conductive carbon material EC-200L: Carbon black (manufactured by Lion Specialty Chemicals: Lionite EC-200L)
・MA14: Oxidized carbon black (manufactured by Mitsubishi Chemical Corporation: MA14)
Water-based resin/PVP: Polyvinylpyrrolidone (Fuji Film Wako Pure Chemical Industries: K-30)
Binder W-168: Emulsion type acrylic resin dispersion solution (manufactured by Toyochem: W-168)
・PVDF: KF polymer (manufactured by Kureha: #9100)
Solvent/NMP: N-methylpyrrolidone

<Preparation of electrode for enzyme power generation device>
[Example 1]
(Preparation of enzyme power generation device electrode (1))
Electrode composition (1) for an enzyme power generation device was dried using a doctor blade so that the basis weight of the enzyme power generation device electrode after drying was 2 mg/cm ² using Toray carbon paper made of carbon fiber as a conductive support. It was applied onto a substrate and dried at 95° C. for 80 minutes in the air to produce an enzyme power generation device electrode (1).

[Example 2]
(Preparation of enzyme power generation device electrode (2))
The enzyme power generation device electrode (2) was prepared in the same manner as the enzyme power generation device electrode (1) described above, except that the enzyme power generation device electrode composition (1) was changed to the enzyme power generation device electrode composition (2). Created.

[Example 3]
(Preparation of enzyme power generation device electrode (3))
The electrode composition (3) for an enzyme power generation device was dried using a doctor blade so that the basis weight of the enzyme power generation device electrode after drying was 2 mg/cm ² , using Toray carbon paper made of carbon fiber as a conductive support. It was coated on a substrate, dried in the air at 95° C. for 80 minutes, and then treated with a UV-O3 device for 20 minutes to produce an enzyme power generation device electrode (3).

[Example 4]
(Preparation of enzyme power generation device electrode (4))
An enzyme power generation device electrode (4) was produced in the same manner as the enzyme power generation device electrode (3) described above, except that the treatment time using the UV-O3 device was 40 minutes.

[Example 5]
(Preparation of enzyme power generation device electrode (5))
An enzyme power generation device electrode (5) was produced in the same manner as the enzyme power generation device electrode (3) described above, except that the treatment time using the UV-O3 device was 60 minutes.

[Example 6]
(Preparation of enzyme power generation device electrode (6))
An enzyme power generation device electrode (6) was produced in the same manner as the enzyme power generation device electrode (3) described above, except that the treatment time using the UV-O3 device was 120 minutes.

[Comparative example 1]
The electrode composition (3) for an enzyme power generation device was dried using a doctor blade so that the basis weight of the enzyme power generation device electrode after drying was 2 mg/cm ² , using Toray carbon paper made of carbon fiber as a conductive support. It was applied onto a substrate and dried at 95° C. for 80 minutes in the air to produce an enzyme power generation device electrode (7).

[Comparative example 2]
The enzyme power generation device electrode (7) was treated with a UV-O3 device for 180 minutes to produce an enzyme power generation device electrode (8).

[Comparative example 3]
The electrode composition (4) for an enzyme power generation device was dried using a doctor blade so that the basis weight of the enzyme power generation device electrode after drying was 2 mg/cm ² using Toray carbon paper made of carbon fiber as a conductive support. It was applied onto a substrate and dried at 95° C. for 80 minutes in the air to produce an enzyme power generation device electrode (9).

[Comparative example 4]
The electrode composition (5) for an enzyme power generation device was dried using a doctor blade so that the basis weight of the enzyme power generation device electrode after drying was 2 mg/cm ² , using Toray carbon paper made of carbon fiber as a conductive support. It was applied onto a base material, dried in the air at 120° C. for 80 minutes, and then treated with a UV-O3 device for 15 minutes to produce an enzyme power generation device electrode (10).

<Preparation of negative electrode for enzyme power generation device>
After dropping a methanol solution of tetrathiafulvalene onto the enzyme power generation device electrodes (1) to (10) and letting it air dry, an aqueous glucose oxidase solution was added dropwise to the electrodes (1) to (10) for the enzyme power generation device, and the electrodes were air dried to form the negative electrodes (1) to (10) for the enzyme power generation device. Created.

<Enzyme power generation device performance evaluation>
The current performance of the negative electrode for an enzyme power generation device was evaluated as follows.
The negative electrodes (1) to (10) for enzyme power generation devices prepared above were used as a working electrode, the platinum coiled electrode was used as a counter electrode, and the silver-silver silver chloride electrode (Ag/AgCl) was used as a reference electrode, using an electrolytic solution containing 1M glucose dissolved therein. (ion conductor) in 0.5M phosphate buffer (pH 7.0). After that, in cyclic voltammetry (CV) measurement in the potential range of -0.2 to 0.5 V at pH 7 and room temperature using a potentio-galvanostat, the maximum The current (mA/cm ² ) was compared.
As an index of current performance, a relative value with the maximum current density of the negative electrode (7) for an enzyme power generation device produced in Comparative Example 1 as 100 was used.
The results obtained are shown in Table 2.

Compared to the comparative example, the example exhibited higher current performance in the electrode for an enzyme power generation device. This is considered to be because the hydrophilicity of the electrode was higher than that of the comparative example, and the permeation of the electrolyte was improved, allowing fuel and ions to be supplied to the inside of the electrode.
On the other hand, when the hydrophilicity of the electrode exceeds 1.0, the affinity of the electrode surface for the electrolytic solution becomes too high, and the supported enzyme and aqueous resin are likely to be eluted, resulting in a decrease in performance. As described above, it has become clear that when the hydrophilicity of the electrode is in an appropriate range (0.15 to 1.0), high current performance is exhibited.

Claims (9)

An electrode for an enzyme power generation device containing a conductive material and a resin material, the electrode having a hydrophilicity of 0.15 to 1.00. The electrode for an enzyme power generation device according to claim 1, wherein the resin material contains a water-soluble resin. The electrode for an enzyme power generation device according to claim 2, wherein the water-soluble resin contains at least one water-soluble resin selected from the group consisting of polyvinylpyrrolidone, polyvinyl alcohol, polystyrene sulfonic acid, polyacrylic acid, and carboxymethyl cellulose. The electrode for an enzyme power generation device according to any one of claims 1 to 3, wherein the conductive material contains a conductive carbon material. 5. The electrode for an enzyme power generation device according to claim 4, wherein the conductive carbon material includes at least one conductive carbon material selected from the group consisting of carbon black, graphene-based carbon materials, carbon nanotubes, and graphite. The electrode for an enzyme power generation device according to claim 4 or 5, wherein the conductive carbon material includes an oxidized conductive carbon material. The electrode for an enzyme power generation device according to any one of claims 1 to 6, further comprising an oxidoreductase. An enzyme power generation device comprising the electrode for an enzyme power generation device according to any one of claims 1 to 7. The enzyme power generation device according to claim 8, wherein the fuel and/or the sensing object contains at least one selected from the group consisting of glucose, lactic acid, and fructose.