Cathode electrode

Abstract

To provide a cathode electrode usable in fuel cells. [Solution] A cathode electrode combining a reductase and amorphous carbon, and a fuel cell equipped therewith The present invention provides a pond and a method for generating electricity.

Description

[Technical Field]

[0001] This disclosure relates to a cathode electrode. [Background technology]

[0002] In conventional enzyme fuel cells, the cathode electrode is typically bilirubin oxidase (BOD )Electrodes were known (e.g., Non-Patent Document 1). In this system, the BO on the surface of the cathode electrode D accepts electrons and reduces oxygen in the air to water. However, BOD is industrial It is not widely available as an enzyme and is relatively expensive compared to other enzymes. While batteries using platinum as the cathode electrode were known, platinum materials were expensive.

[0003] Another cathode electrode in enzyme fuel cells is glucose oxidase (GOD). Methods using peroxidase (POD) were also known (for example, Non-Patent Document 2). In this system, the fuel glucose is oxidized to gluconolactone by GOD, and then peroxidized. Hydrogen is produced. Then, the POD accepts electrons and reduces the hydrogen peroxide to water. It uses two types of enzymes, both of which are widely available as industrial enzymes and therefore inexpensive. It can be constructed using only enzymes. Furthermore, the battery can be fabricated using the same fuel as the anode electrode. It also has the advantage of being easy to use in glucose fuel cells.

[0004] However, as a reported example of a battery using a cathode electrode combining GOD and POD, For example, the open-circuit voltage of the battery disclosed in Non-Patent Document 2 was 0.45V. The redox potential of the mediator at the anode electrode of the battery is approximately -0.05V (vs. Ag / The oxidation initiation potential upon addition of glucose (AgCl) is approximately -0.1V (vs. Ag / AgCl). Therefore, the potential of the cathode electrode is around 0.35~0.4V, and in terms of performance, However, this was not sufficient. In the cyclic voltammogram of the cathode electrode, glucos The current density at +0.2V (vs. Ag / AgCl) when adding - is approximately -100μF. A / cm 2 And so it was. Graphite was used as the carbon material.

[0005] As an example of a reported peroxidase electrode, for instance, Non-Patent Document 3 describes using a POD electrode - It is stated that a reduction current is generated from around 0.2V (Figure 5 in the same document). Other reported examples include Non-patent document 4 describes the Ketjenblack EC300J and the Glassy Carbon rotating electrode. A glucose sensor using a combination of POD and GOD is disclosed.

[0006] There is a need for an enzyme electrode cathode that does not require expensive enzymes and can produce greater output. It was

[0007] This specification cites numerous documents, including patent applications and manufacturers' manuals. These documents are not considered to be related to the patentability of the invention, but each individual As in cases where the document is specifically and individually indicated to be incorporated by reference, All reference documents are incorporated herein by reference. [Prior art documents] [Non-patent literature]

[0008] [Non-Patent Document 1] Biosens Bioelectron. 2012 May 15; 35(1): 140-146 [Non-Patent Document 2] Electroanalysis 2013, 25, No. 12, 2677-2683 [Non-Patent Document 3] Anal Biochem 2002, 307, 110-116 [Non-Patent Document 4] Analytical Sciences July 2017, Vol. 33, 839-844 [Summary of the Invention] [Problems to be Solved by the Invention]

[0009] The present disclosure aims to provide a cathode electrode that can at least partially solve the problems of conventional cathode electrodes and can be used in enzymatic fuel cells. [Means for Solving the Problems]

[0010] As a result of intensive research to solve the above problems, the inventors of the present invention, as an example, prepared an enzymatic fuel cell using a cathode electrode combined with glucose oxidase (GOD), peroxidase (POD), and amorphous carbon. Surprisingly, it was found that a cell with an output current several times higher than that of conventional reported examples could be obtained, and the present invention including this as one embodiment was completed.

[0011] The present disclosure includes the following embodiments. [1] A cathode electrode combined with a reductase and amorphous carbon. [2] The electrode according to Embodiment 1, in which an oxidase is further immobilized. [3] The electrode according to Embodiment 2, in which the oxidase generates hydrogen peroxide as a reaction product. [4] The reductase according to any one of Embodiments 1 to 3 is catalase or peroxidase. The electrodes listed below. [5] Embodiments in which the oxidase is glucose oxidase or lactate oxidase An electrode as described in any of 2 to 4. [6] The amorphous carbon is conductive carbon black, as described in any of Embodiments 1 to 5. The electrodes. [7] Conductive carbon black produced by pyrolysis or incomplete combustion, The electrode according to Embodiment 6. [8] An electric device having a cathode electrode and an anode electrode as described in any of Embodiments 1 to 7. pond. [9] The battery according to Embodiment 8, having an anode electrode on which an enzyme is immobilized.

[10] Cathode electrode, anode electrode, fuel tank, and according to any one of embodiments 1 to 7. A fuel cell having an electrolyte.

[11] A method of generating power using a battery as described in any of Embodiments 8 to 10.

[0012] This specification contains the disclosures of Japanese Patent Application No. 2020-103348, which forms the basis of the priority claim of this application. It includes. [Effects of the Invention]

[0013] This disclosure provides a cathode electrode with good output performance. A fuel cell equipped with [a certain feature] is provided. [Modes for carrying out the invention]

[0014] Regarding the cathode electrode In one embodiment, the disclosure provides a cathode electrode. The cathode electrode may be a cathode electrode that combines (or incorporates) a reductase and amorphous carbon. In one embodiment, amorphous carbon is carbon black, activated carbon, carbon fiber - or it may be mesoporous carbon. In one embodiment the cathode electrode is a reducing yeast It may be a cathode electrode that combines (or incorporates) a material and conductive carbon black. In one embodiment, the reductase may be an enzyme capable of reducing hydrogen peroxide. Examples of enzymes that can reduce hydrogen oxide include peroxidase and catalase. However, this is not the only example.

[0015] In one embodiment, the cathode electrode is used to detect glucose oxidase (GOD) and peroxide. It may contain xidase (POD) and amorphous carbon, preferably conductive carbon black. Solid carbon materials include nanocarbons such as carbon nanotubes and fullerenes, and diamonds. Examples of three-dimensional crystals include mondo and graphite, (conductive) carbon black and activated carbon, and Amorphous carbon (amorphous carbon) such as carbon fiber and mesoporous carbon It is broadly divided into (also called amorphous carbon). In this specification, the term amorphous carbon is generally used. It is used in a general sense. In other words, amorphous carbon refers to carbon that does not have a clear crystalline structure. It has a taste. Conductive carbon black is generally a substance that can impart conductivity to an object with a small amount of addition. It is a carbon black material. In one embodiment, conductive carbon black is a This is a Ketjenblack. The Ketjenblack usable for the cathode electrode of this disclosure is Lionite EC200L, Ketchenblack EC300J, Lionite CB, Ketchenblack Chembrake EC600JD, and its crushed products, such as carbon ECP200L Examples include carbon ECP and carbon ECP600JD, but these are not the only options. Ketjen Black International Company It is available from Company Y or Lion Specialty Chemicals, Inc. Another implementation In one embodiment, the conductive carbon black is acetylene black. In another embodiment... Furthermore, conductive carbon black is Denka Black (registered trademark). Activated carbon is made from charcoal. By activating the raw material using high temperatures and steam, the number of micropores is increased, making it more effective than charcoal. The adsorption performance has been increased by 5 to 10 times. The main types of activation treatment are gas activation and chemical activation. There are two types of laws. Mesoporous carbon has regularly spaced pores on the nanometer scale. It is carbon.

[0016] In one embodiment, carbon black is produced by a pyrolysis method or an incomplete combustion method. Obtain. For information on the manufacturing method of conductive carbon black, see "Current Status of Conductive Carbon Black" (Japanese). A report exists in Volume 44, Number 3 of the Journal of the Printing Society of Japan. The full contents of these documents can be found by referring to them. To be included in the detailed specifications. As for pyrolysis methods, the thermal black method and the acetylene black method are Examples include the oil furnace process using aromatic oils and natural gas. Examples include the gas furnace method using a different method. In another embodiment, a pyrolysis method or an incomplete method may be used. Carbon black produced by combustion is secondarily treated with nitric acid, nitrogen dioxide, ozone, etc. Furthermore, by performing a treatment (oxidation treatment) that actively increases the acidic functional groups, the particle surface is modified / altered. This can also be done. In another embodiment, instead of oxidation treatment, steam is used at a high temperature of 900°C or higher. The particle surface is modified by an activation treatment in which it is brought into contact with carbon dioxide, which removes crystallites and forms pores. It can also be processed (also called gasification). A typical carbon brace that undergoes activation treatment. The black is Ketjenblack. In another embodiment, at 2000°C in an inert atmosphere. The material is treated at high temperatures from 3000°C to eliminate surface functional groups and promote the growth of crystals within the particles. It is also possible to induce this process, change the particle shape from spherical to polyhedral, and modify the particle surface (graphitization). (Also called processing). In this specification, conductive carbon black is simply referred to as carbon black. That happens.

[0017] Ketjenblack EC300J is a granular product with a particle size of 2-4 mm and a bulk density of 130 g / L. It is a conductive carbon black in a specific form. Also, Ketjenblack EC300J is DBP The oil absorption capacity (ml / 100g) is 365, the primary particle size (nm) is 40, and the BET ratio is Surface area (m 2 The % (per g) is 800, the porosity (%) is 60, and the volatile content (%) is 0.5 The ash content (%) is 0.1 and the median diameter (Dmed, nm) is 125. It possesses the following physical properties. DBP oil absorption refers to the amount of dibutyl phthalate (DBP) absorbed. Carbon black particles fuse together, forming aggregates that are linked together in a grape-like pattern. This is called the structure. The size of the structure, like the particle size, is determined by the carbon This affects the blackness and dispersion of the black pigment. Generally, the larger the structure, the better the dispersion. It becomes more desirable, but the blackness decreases. Also, carbon black with a large structure is excellent. It indicates the conductivity. The structure can be indirectly evaluated by the amount of DBP absorption. BET specific surface area is the specific surface area measured by the BET method (gas adsorption method). Volatile components are measured by car. When Bombrak is placed in a crucible and heated at 950°C for 7 minutes, the volatile components, i.e., the weight loss, are measured. This is because the surface functional groups of carbon black detach as CO, H2O, CO2, etc. This is based on the bulk density of carbon black filled in a container of a certain volume under certain conditions. This is the mass per unit volume.

[0018] In another embodiment, carbon black can be produced by the acetylene process. For example, Denka Black (registered trademark) is a type of carbon black, and contains acetylene. It is manufactured by thermal decomposition. Therefore, Denka Black (registered trademark) is acetylene black. It can be said to be a type of [unclear]. Denka Black (registered trademark) has particles linked together in a chain, and also, Laphite formation is highly advanced. Denka Black (registered trademark) is of high purity and undivided. The hydrogen content present as solutions or functional groups is extremely low, and there are almost no oxygen-containing functional groups. It is not possible. Denka Black (registered trademark) is available in powder, pressed, and granular forms depending on its shape. The powdered product is a light powder as it is produced in the decomposition furnace. The pressed product is made by pressing the powdered product. It has increased bulk density. The granular product is a granular material with high bulk density. Denka Black ( The grades (registered trademark) are FX-35, HS-100, 50% press, and 100% press. It is commercially available (Denka Co., Ltd.).

[0019] Carbon black #3230B (manufactured by Mitsubishi Chemical Corporation) has a particle size of 23 nm and is nitrogen adsorbent. The specific surface area is 220, the DBP absorption of the granular product is 140, and the volatile content is 1.4%. The pH value is 6.4 and the ash content is 0.2. The particle size referred to here is the carbon brim. This is the arithmetic mean diameter obtained by observing rack particles with an electron microscope. Also, the nitrogen adsorption referred to here is... The specific surface area is calculated using the S-BET formula from the nitrogen adsorption amount, in accordance with JIS K6217. Yes. Also, the DBP absorption amount referred to here is based on carbon black according to JIS K6221. This is the amount of DBP absorbed by 100g. Also, the volatile components referred to here are 9g of carbon black. This is the volatile content, or loss in volume, after heating at 50°C for 7 minutes. Also, the pH value mentioned here. This is the value measured using a glass electrode pH meter for a mixture of carbon black and distilled water. Furthermore, the ash content referred to here is determined in accordance with JIS K6218, by heating carbon black at 750°C. This is the residue after it has been incinerated. Carbon black #3230B (manufactured by Mitsubishi Chemical Corporation) is approximately 2 Fuel and air are introduced into a reaction chamber lined with bricks that can withstand temperatures up to 1,000°C, and complete combustion is performed. By heating, a high-temperature atmosphere of over 1,400°C is created, and liquid raw material oil is continuously sprayed into it. It is produced by thermal decomposition.

[0020] The physical properties and manufacturing process of each carbon black are described in the product catalog. The physical properties of the rack can be determined as appropriate by conventional methods, official methods, JIS standards, international standards, etc. In this specification, unless otherwise specified, the particle size of carbon black refers to the particle size of carbon black. The arithmetic mean diameter is determined by observing the buck particles with an electron microscope. In this specification, unless otherwise specified... Unless otherwise specified, the nitrogen adsorption specific surface area of ​​carbon black is determined according to JIS K6217. The specific surface area is calculated from the amount applied using the S-BET formula. Unless otherwise specified in this specification, The DBP absorption amount of carbon black is calculated according to JIS K6221 for carbon black 10 This refers to the amount of DBP absorbed by 0g. In this specification, unless otherwise specified, carbon black The volatile components of the carbon black are the volatile components (weight loss) when the carbon black is heated at 950°C for 7 minutes. In this specification, unless otherwise specified, the pH value of carbon black refers to carbon This value was measured using a glass electrode pH meter on a mixture of black and distilled water. Unless otherwise specified, the ash content of carbon black is defined in accordance with JIS K6218. This is the residue after ashing of carbon black at 750°C. Carbon ECP200L, car Bon ECP and carbon ECP600JD have a 75μm pass, i.e., a 75μm filter. It can pass through the router and is a powdered conductive carbon black with a bulk density of 30 (g / L). Therefore, in one embodiment, a conductive material can be used for the cathode electrode of the present disclosure. Conductive carbon black is a granular conductive carbon black with a particle size of 2-4 mm and a bulk density of 130 g / L. It is a von black. Also, in one embodiment, it can be used for the cathode electrode of this disclosure. The conductive carbon black has a DBP oil absorption rate (ml / 100g) of 365, and the primary particles The particle size (nm) is 40, and the BET specific surface area (m²) is 40. 2 The porosity (%) is 800 (per g), and the porosity (%) is 800. The ratio is 60, the volatile content (%) is 0.5, the ash content (%) is 0.1, and the median diameter is This is a conductive carbon black with a physical property value of Dmed (nm) of 125. Furthermore, in one embodiment, conductive carbon brass usable for the cathode electrode of the present disclosure The material is a conductive powder with a particle size of less than 75 μm (75 μm pass) and a bulk density of 30 (g / L). It is carbon black. In one embodiment, conductive carbon black is Denka Black It may be (registered trademark). In one embodiment, conductive carbon black is Denkabra It may be FX-35. In one embodiment, conductive carbon black is Denkabra It is a 100% pressed product. In one embodiment, conductive carbon black is Denkabu This is a rack 50% pressed product. In one embodiment, conductive carbon black is Denkab. This is rack HS-100. In one embodiment, conductive carbon black is carbon It is black #3230B (manufactured by Mitsubishi Chemical Corporation).

[0021] In this specification, unless otherwise specified, the basic particle size refers to the aggregate (primary aggregate). The minute spherical parts that make up the structure are considered as primary particles, and their diameters are measured using the circular approximation. The basic particle size is also called the primary particle size, and this is determined from electron microscope images using an image analysis device. It can be measured. Alternatively, the primary particle diameter can be measured by orienting the projected individual particles as close to a circle as possible using electron microscopy. The diameter can be measured in a similar manner. For example, an automated particle size analyzer manufactured by Zeiss can be used. In the specification, unless otherwise specified, the average particle size of the primary particle diameter refers to the arithmetic mean particle size of the primary particle diameter. This refers to the diameter. For example, carbon black nanoparticles are IG-1000 Plus (Shimadzu Corporation). It can be measured by the IG-1000 Plus. The particle size distribution of Bombrak nanoparticles can be measured. Unless otherwise specified herein, When we simply refer to the particle size of carbon black, we are referring to the particle size of the aggregates. Particle size can be measured with a particle size analyzer. In this specification, unless otherwise specified, the particle size of nanoparticles is The primary particle size is measured using IG-1000 Plus (Shimadzu Corporation), and the particle size of the aggregate is also measured. The particle size is defined as the particle size measured using a Partica LA-960V2 manufactured by Horiba, Ltd.

[0022] In one embodiment, the conductive carbon black used in the electrodes of this disclosure is derived from the carbon Nanotubes are excluded. Note that this is the conductive carbon black used in the electrodes of this disclosure. This does not prevent the presence or inclusion of trace amounts of carbon nanotubes. In other words, in one embodiment, the conductive carbon black used in the electrodes of the present disclosure is changed to a different type of carbon black. Removal of bon nanotubes means that the main component of the conductive carbon black used in the electrodes of this disclosure is... This means that the main component is conductive carbon black, not carbon nanotubes. In this context, the main component refers to a component that makes up 90% or more by weight, for example, 95% or more.

[0023] Commercially available products can be used as activated carbon, carbon fiber, or mesoporous carbon. .

[0024] As a reductase, an enzyme capable of reducing hydrogen peroxide can be used. Enzymes that can reduce hydrogen dioxide include peroxidase (POD, EC 1.11). Examples include .1.7) and catalase (EC 1.11.1.6). Peroxidase Any known peroxidase can be used as the (POD). Examples of peroxidases include those derived from horseradish, rice, and soybeans. Commercial products and Therefore, PEO-131 (manufactured by Toyobo), PEO-301 (manufactured by Toyobo), PEO-302 ( Examples include catalases manufactured by Toyobo Co., Ltd., etc. Any known catalase can be used as the catalase. Yes, it is possible. Catalase can be found, for example, in Aspergillus niger and bovine liver. Examples of origins include, but are not limited to, peroxidase Alternatively, catalase can be immobilized on the electrode material. Immobilization methods include... Methods using agents or crosslinking reagents, methods of encapsulation in a polymer matrix, and coating with a dialysis membrane. Methods include using photocrosslinkable polymers, conductive polymers, and redox polymers. They may be fixed in a polymer or adsorbed onto an electrode, or these can be combined It may be used. Glutaraldehyde is an example of a fixative. When using a ion, glutaraldehyde is used to remove peroxidase from the electrode (for example, a carbon electrode). After immobilization on the electrode, the glutaraldehyde is blocked by treatment with a reagent containing an amine group. The amount of peroxidase to be immobilized is the amount that can generate the current necessary for fuel cell power generation. This can be done, and can be decided as appropriate.

[0025] In one embodiment, the cathode electrode may further have an oxidase immobilized on it. In one embodiment, the oxidase produces hydrogen peroxide as a reaction product. In one embodiment, a known oxidase can be used as the oxidase. Examples of oxidases include glucose oxidase, lactate oxidase, and amino acid oxidase. Examples include acid oxidase and sarcosine oxidase. Glucose oxidase (G As the OD, any known glucose oxidase can be used. Morphologically, glucose oxidase can be immobilized on electrode materials. In this application method, glucose oxidase is not immobilized on the electrode material. The activating agent may be the same as in the case of the peroxidase described above. In one embodiment, glucose As for soxidases, GODs derived from the genus Aspergillus, for example, Aspergillus Examples include GOD derived from llus niger. In another embodiment, glucose oxy As for sidase, Toyobo's GOD (catalog number GLO-201, Asperg (derived from illus sp.), GOD from Fujifilm Wako Pure Chemical Industries (Wako Pure Chemical Industries catalog number) 074-02401 (derived from Aspergillus niger), Sigma-Ald rich GOD type VII (derived from Aspergillus niger), and and Sigma-Aldrich GOD type XS(Aspergillus (derived from niger) is one example, but it is not limited to this. Lactate oxidase (EC 1.1.3 2) Any known lactate oxidase can be used, for example, Lactoco Derived from ccus lactis, derived from Aerococcus viridans, and En Examples include those derived from *Terococcus sp.*, but are not limited to this. Amino acid oxy Sidase (EC 1.4.3.2) is derived from microorganisms or snakes, such as vipers. This includes, but is not limited to, species originating from the family Viperinae and Elapidae. As for the sarcosine oxidase (EC 1.5.3.1) (also called sarcosine oxidase), Bacterium, Bacillus, Cylindrocarbon, Pseudomonas, Arthrobac Examples include those derived from the genus Thar and their modified forms (Japanese Patent Publication No. 2005-176828, Japanese Patent Publication No. 2 (005-168487, JP 2000-175685). The above oxidase is a commercially available product. It is also possible to do so. Furthermore, with respect to genes and enzymes, "origin" as used in this specification refers to a specific organism. This includes not only the wild type, but also mutants and variants derived from the wild type, and even the wild type itself. This includes mutants obtained by modifying the original sequence. Furthermore, artificially synthesized sequences are also included. If the type and sequence match, it is included in the origin. Artificial forms that are highly similar to the wild type. The same applies to composite sequences. Here, "high similarity" means that when comparing the two sequences... This means that the difference is only to the extent that one or a few amino acids are substituted, deleted, or added. Here, "several" refers to a maximum of 15, 14, ... 3, or 2 items.

[0026] Method for manufacturing a cathode electrode In one embodiment, the present disclosure provides a method for manufacturing a cathode electrode. This method involves carbon Disperse the raw material (e.g., Ketjenblack) in a suitable solvent such as methanol, and then... The process involves coating the electrode (e.g., a carbon electrode or a carbon printed electrode) and drying it, and peroxide Apply sidase and an enzyme immobilizer (e.g., glutaraldehyde) to the electrodes and let them dry. The process may include, and may also include, a step of agitating and washing the electrodes in water (e.g., pure or ultrapure water). The manufactured cathode electrodes can be incorporated into fuel cells.

[0027] In one embodiment, the present disclosure provides a battery having the above-described cathode electrode. In an embodiment, the battery of the present disclosure has peroxidase immobilized on the cathode electrode. Furthermore, the cathode electrode is treated with a carbon material that imparts conductivity. Glucose oxidase is present on the sword electrode side. It may be immobilized or present in a solution. In one embodiment, the electric A method of generating electricity using a pond is provided.

[0028] In one embodiment, the present disclosure provides a fuel cell. In one embodiment, the present disclosure The fuel cell comprises the cathode electrode, anode electrode, fuel tank, and electrolyte described above. The fuel cell of this disclosure may optionally have a load resistor placed between the anode and the cathode. It is possible to do so and may be equipped with wiring for that purpose. In one embodiment, the load resistance is the fuel of the present disclosure It is part of the battery. In one embodiment, the load resistance is not part of the fuel cell of this disclosure. Furthermore, the fuel cell of this disclosure is configured to be connected to an appropriate load resistor.

[0029] Regarding the anode electrode In one embodiment, the anode electrode may be a carbon electrode or a metal electrode. For example, Electrodes made of conductive carbonaceous materials such as carbon black, graphite, and activated carbon, or gold, platinum, etc. Electrodes made of metal can be used. Specifically, carbon paper, glass, etc. Examples include carbon, HOPG (highly oriented pyrolysis graphite), etc. Also, the anode is acid. It can come into contact with reductases, such as glucose oxidase or glucose dehydrogenase. It may be configured such that the anode in the fuel cell of the present disclosure The oxidoreductase used constitutes part of the anode. For example, the oxidoreductase is part of the anode. It may be in close proximity to or in contact with, immobilized, or adsorbed to. The fuel tank contains compounds that serve as substrates for oxidoreductases immobilized on electrodes. For example, gluco When glucose oxidase or glucose dehydrogenase is immobilized on the electrode, the fuel is glucose It could be a course. For example, fructose oxidase or fructose dehydrogenase. If immobilized on the electrode, the fuel could be fructose. For example, invertase and glucose. A combination of coarse dehydrogenase or glucose oxidase is immobilized on an electrode. In combination, the fuel may be sucrose. For example, amylase and glucose dehydrogenase or If a combination of glucose oxidases is immobilized on the electrodes, the fuel could be starch. In one embodiment, the fuel cell of the present disclosure uses an ion exchanger to separate the anode and cathode. It may have an ion exchange membrane. The ion exchange membrane may have pores ranging from 1 nm to 20 nm.

[0030] In one embodiment, the oxidoreductase used in the anode electrode is flavin adenine. It may be a creotide (FAD)-dependent glucose dehydrogenase (GDH). In this specification, FAD refers to adenine dinucleotide-dependent glucose dehydrogenase. It is sometimes denoted as -GDH. FAD-GDH is used for the Aspergillus genus and Botryohium. Zinnia, Mucor, Absidia, Actinomuc FA derived from the genera Actinomucor and Circinella Examples include D-GDH.

[0031] Examples of microorganisms of the genus Mucor include Mucor prainii and Mucor jav. anicus, Mucor circinelloides f. circinell oides, Mucor guilliermondii, Mucor hiemali s, Mucor hiemalis f. silvaticus, Mucor sub tilissimus, Mucor RD056860, Mucor dimorpho Examples include *sporus*, etc. An example of a microorganism of the genus Absidia is Absidia. Examples include *Cylindrospora* and *Absidia hyalospora*. Yes. An example of a microorganism of the genus Actinomucor is Actinomucor ele One example is gans. An example of a Circinella genus microorganism is Circ inella minor, Circinella mucoroides, Circi nella muscae, Circinella rigida, Circinell a simplex, Circinella umbellata, Circinell a minor, Circinella mucoroides, Circinella muscae, Circinella rigida, Circinella sim plex, Circinella umbellata, Circinella RD0 Examples include 55423 and Circinella RD055422. RD strains are from NBRC (National Biotechnology Center, National Institute of Technology and Evaluation). These are the stored bacterial strains. FAD-GDH derived from these strains and their variants can be used.

[0032] In another embodiment, the oxidoreductase used in the anode electrode is fructose dehydrogenase. It may be a genase (EC 1.1.99.11). Fructose dehydrogenase is D-fructose dehydrogenase, also known as fructose-5-dehydrogenase. Fructose dehydrogenase converts D-fructose into 5-dehydro-D-fructose. It catalyzes the reaction that reduces to Glu. While some examples are derived from *Conobacter industrius*, this is not the only one. Fructose dehydrogenator derived from Gluconobacter industrius. You may use commercially available products or equivalent or comparable products for the ze.

[0033] In one embodiment, a medium having the property of adsorbing to the electrode is attached to the anode electrode side of the battery. Eta can be used. Mediator (artificial electron mediator, artificial electron acceptor, electron A mediator (also called a mediator) receives electrons from the oxidoreductase enzyme used in the anode electrode. It is not particularly limited as long as it can do so. Examples of mediators include quinones and phenazines. Viologens, cytochromes, phenoxazines, phenothiazines, ferricyanides Substances such as potassium ferricyanide, ferredoxins, ferrocene, osmium complexes Examples include phenazine compounds and their derivatives, such as PMS and methoxy-P. MS is one example, but is not limited to it. A mediator having the property of adsorbing to an electrode is also used. For this, see International Publication No. 2019 / 198359 (PCT / JP2019 / 007373), Japanese Patent Publication No. 2019-186122 (Patent No. 6484741), or Japanese Patent Publication No. 2019-18033 Examples include those described in 5 (Patent No. 6484742), for example, N-isopropyl-N'- Phenyl-p-phenylenediamine (IPPD), N,N'-diphenyl-p-phenyl Diamine (DPPD), N-(1,3-dimethylbutyl)-N'-phenyl-p-phenyl Examples include, but are not limited to, nitrenediamine (6PPD).

[0034] In the electrode, the enzyme may be placed in any position. In one embodiment, the electrode is It may be placed on a surface that comes into contact with fuel or oxygen. The electrode increases the surface area that comes into contact with fuel or oxygen. To improve power generation efficiency, for example, an electrode with pores is formed and enzymes are introduced into the pores. It can be arranged. From the viewpoint of forming electrodes with pores, particulate material can be used as the conductive material. For example, particulate materials having pores can be used.

[0035] In a power generation device, the electrodes may be positioned in any location. In one embodiment, The electrode material can be applied to the substrate by screen printing or the like to form it. This is preferable from the viewpoint of making the chair thinner. In this case, the anode and cathode are formed on the same substrate. Alternatively, the anode and cathode may be formed on different substrates.

[0036] The substrate may have lead portions for electrically connecting electrodes. The lead portions are generally used It can be formed using a conductive material. The lead portion has a through hole in the part that contacts the cathode. This is possible. This allows for an increase in the supply of oxygen to the cathode.

[0037] The material of the substrate used to form the electrodes may be a natural material or a synthetic material, and is not particularly limited. The material may be, for example, paper or cloth made from natural materials, but is not limited to these. In a specific embodiment... This involves using a water-repellent substrate or a substrate made of a material that does not absorb liquids. Yes, it is possible. This prevents a short circuit between the anode and cathode caused by the liquid supplied to the power generation device. This can be prevented from occurring. Alternatively, a spacer may be placed between the anode and cathode. This prevents a short circuit between the anode and cathode.

[0038] The shape of the electrodes, for example, the shape of the electrodes in a power generation device, can be anything. It is not limited to this. The shape can be, for example, a pattern of multiple anodes or cathodes connected together. This can be achieved. This can improve power generation efficiency.

[0039] (Other components) A power generation device may, in some cases, have other components besides fuel and electrodes. For example, Protective material for protecting power generation devices from the outside air, and for fixing power generation devices to an adherend. Examples include adhesives and hydrogels, but are not limited to these.

[0040] In certain embodiments, the power generation device uses the electricity generated to supply liquid The means for measuring the concentration of substances throughout the body, the means for wirelessly transmitting the data obtained from the measurement, and other similar means are further included. It is possible to have.

[0041] In one embodiment, a method of generating electricity using the fuel cell of the present disclosure is provided. The method includes the step of supplying fuel to the anode. Once fuel is supplied to the anode, the substrate becomes acidic. The electrons are converted and simultaneously generated, then transferred to the anode electrode, and from the anode electrode through wiring (external An electric current is generated when electrons travel through the circuit and reach the cathode electrode.

[0042] Protons (H) generated in the above process + ) moves through the electrolyte solution to the cathode electrode. And at the cathode electrode, protons that have moved from the anode through the electrolyte solution and , electrons that have moved from the anode side via an external circuit, and oxidizing agents such as oxygen and hydrogen peroxide ( The sword-side substrate reacts with the reaction to produce water. This can be used to generate electricity.

[0043] In one embodiment, depending on the type of enzyme used in the anode, known electron transfer mediators Ta may be used. In one embodiment, the fuel to be used in the fuel tank is selected according to the type of enzyme. It is possible. As fuels, sugars, alcohols, aldehydes, amino acids, amines, and lactic acid Examples include, but are not limited to, uric acid. The fuel can be one or more types. For example, When using glucose dehydrogenase, the fuel tank may contain glucose. If fructose dehydrogenase is used, the fuel tank may contain fructose. Alternatively, if lactate oxidase is used, the fuel tank may contain lactic acid.

[0044] In one embodiment, an impurity (ascorbic acid) interferes with the electrode reaction at the cathode. To avoid the effects of uric acid, etc., oxygen-selective membranes (e.g., dimethylpolysiloxane) A film (of which is a type of film) can be placed around the cathode electrode.

[0045] In one embodiment, the cathode electrode of the present disclosure can be used in a battery. In this embodiment, the cathode electrode of the present disclosure can be used in a fuel cell. Another embodiment In this disclosure, the cathode electrode can be used for power generation. These are examples, and this disclosure The applications of the cathode electrode shown are not limited to this.

[0046] The present invention is further illustrated by the following embodiments. However, the technical scope of the present invention is limited to that. These examples do not limit the scope in any way. [Examples]

[0047] [Example 1] (Preparation of carbon black solution) Denka Black FX-35 (manufactured by Denka Co., Ltd.) in a 50% ethanol solution at a concentration of 20 mg / ml Suspend the mixture as described above, and use an ultrasonic homogenizer (Nippon Seiki Co., Ltd., US-150E, output 30%). It was processed for more than 3 minutes.

[0048] (Electrode fabrication) Apply 20 μl of the above carbon black suspension to each side of a 0.5 mm square piece of carbon cloth. The cloth was dried at 60°C for more than one hour. Subsequently, a final concentration of 5 mg / ml peroxidase was added. (POD, manufactured by Toyobo Co., Ltd.) and 20 μl of 5% glutaraldehyde solution were applied and left at room temperature for 2 hours. The electrodes were fabricated by drying.

[0049] (Electrochemical measurement) The above electrode is used as the working electrode in the ALS electrochemical analyzer 814D (manufactured by BAS). The wires were connected and the device was immersed in 10 ml of 100 mM potassium phosphate buffer (pH 7.0). Using a silver-silver chloride electrode (manufactured by BAS) as the reference electrode and a platinum electrode (manufactured by BAS) as the counter electrode, the solution was analyzed. While stirring at 400 rpm, increase the voltage from +200 mV to +700 mV (vs. Ag / AgC). A cyclic voltammetry (CV) measurement was performed by sweeping the voltage within the range of l). Sweep speed The temperature was set to 20 mV / sec. Subsequently, hydrogen peroxide solution was added to achieve a final concentration of 1 mM. Similarly, CV measurements were performed. Cyclic voltammograms were obtained before and after the addition of hydrogen peroxide solution. The comparison showed that at potentials below approximately +570mV (vs. Ag / AgCl), peroxide A higher reduction current was observed after adding the hydrogen peroxide solution compared to before adding the hydrogen solution. At 200mV (vs. Ag / AgCl), the results were compared to before the addition of hydrogen peroxide solution. After adding hydrogen peroxide solution, the current was 331 μA / cm². 2 A high reduction current was observed.

[0050] [Example 2] (Preparation of carbon black solution) 70 mg of Denka Black 100% pressed product (manufactured by Denka Co., Ltd.) in a 50% ethanol solution. The mixture was suspended to a concentration of / ml and treated with an ultrasonic homogenizer for at least 3 minutes.

[0051] (Electrode fabrication) Apply 20 μl of the above carbon black suspension to each side of a 0.5 mm square piece of carbon cloth. The cloth was dried at 60°C for at least one hour. Subsequently, a final concentration of 5 mg / ml POD and 5% Glutamate were added. Electrodes were prepared by coating them with 20 μl of taraldehyde solution and drying them at room temperature for 2 hours.

[0052] (Electrochemical measurement) Using the above electrode as the working electrode, CV measurement was performed in the same manner as in Example 1. Hydrogen peroxide solution was added. A comparison of cyclic voltammograms before and after addition showed approximately +570mV (vs. Ag / At potentials below AgCl, the hydrogen peroxide solution is compared to the potential before adding the hydrogen peroxide solution. A high reduction current was observed after addition. At +200mV (vs. Ag / AgCl) The current level after adding the hydrogen peroxide solution was 326 μA / cm², compared to before adding the hydrogen peroxide solution. 2 A high reduction current was observed.

[0053] [Example 3] (Preparation of carbon black solution) 70 mg of carbon black #3230B (manufactured by Mitsubishi Chemical Corporation) in a 50% ethanol solution. The mixture was suspended in ml and treated with an ultrasonic homogenizer for at least 3 minutes.

[0054] (Electrode fabrication) Apply 20 μl of the above carbon black suspension to each side of a 0.5 mm square piece of carbon cloth. The cloth was dried at 60°C for at least one hour. Subsequently, a final concentration of 5 mg / ml POD and 5% Glutamate were added. Electrodes were prepared by coating them with 20 μl of taraldehyde solution and drying them at room temperature for 2 hours.

[0055] (Electrochemical measurement) Using the above electrode as the working electrode, CV measurement was performed in the same manner as in Example 1. Hydrogen peroxide solution was added. A comparison of cyclic voltammograms before and after addition showed approximately +490mV (vs. Ag / At potentials below AgCl, the hydrogen peroxide solution is compared to the potential before adding the hydrogen peroxide solution. A high reduction current was observed after addition. At +200mV (vs. Ag / AgCl) The concentration after adding the hydrogen peroxide solution was 361 μA / cm², compared to before adding the hydrogen peroxide solution. 2 A high reduction current was observed.

[0056] [Example 4] (Preparation of carbon black solution) Ketjenblack ECP600JD (manufactured by Lion Specialty Chemicals) Suspend the substance in a 50% ethanol solution to a concentration of 7 mg / ml and homogenize it in an ultrasonic homogenizer for 3 minutes. It was processed for more than [number] hours.

[0057] (Electrode fabrication) Apply 20 μl of the above carbon black suspension to each side of a 0.5 mm square piece of carbon cloth. The cloth was dried at 60°C for at least one hour. Subsequently, a final concentration of 5 mg / ml POD and 5% Glutamate were added. Electrodes were prepared by coating them with 20 μl of taraldehyde solution and drying them at room temperature for 2 hours.

[0058] (Electrochemical measurement) Using the above electrode as the working electrode, CV measurement was performed in the same manner as in Example 1. Hydrogen peroxide solution was added. A comparison of cyclic voltammograms before and after addition showed approximately +560mV (vs. Ag / At potentials below AgCl, the hydrogen peroxide solution is compared to the potential before adding the hydrogen peroxide solution. A high reduction current was observed after addition. At +200mV (vs. Ag / AgCl) The concentration after adding the hydrogen peroxide solution was 733 μA / cm², compared to before adding the hydrogen peroxide solution. 2 The reduction current was high.

[0059] [Example 5] (Preparation of carbon black solution) Ketjenblack ECP200L (manufactured by Lion Specialty Chemicals) The substance was suspended in a 50% ethanol solution to a concentration of 20 mg / ml.

[0060] (Fabrication of cathode electrodes) Apply 20 μl of the above carbon black suspension to each side of a 0.5 mm square piece of carbon cloth. It was covered with cloth and dried at 60°C for more than 1 hour. Subsequently, glucose oxyphosphate with a final concentration of 5 mg / ml was used. Dase (manufactured by Sigma), POD with a final concentration of 5 mg / ml and 5% glutaraldehyde solution, 2 Electrodes were prepared by coating 0 μl of the material and drying it at room temperature for 2 hours.

[0061] (Electrochemical measurement) Using the above electrode as the working electrode, CV measurement was performed in the same manner as in Example 1. However, as the substrate Instead of hydrogen peroxide solution, glucose solution was added to achieve a final concentration of 10 mM. A comparison of cyclic voltammograms before and after the addition of - showed approximately +640mV (vs. At potentials below Ag / AgCl, compared to before adding glucose solution, the glucose A high reduction current was observed after the addition of the solution.

[0062] (Fabrication of anode electrodes) Single-walled carbon nanotubes are immobilized on a 0.5mm square carbon cloth, and further N-I Sopropyl-N'-phenyl-1,4-phenylenediamine (IPPD, Tokyo Chemical Industry Co., Ltd.) The product (manufactured by [company name], product code P0327) was adsorbed and immobilized. Subsequently, 20 mg / ml of glucose solution was added. 20 μl of hydrogenase (GDH, manufactured by Kikkoman Biochemifa Co., Ltd.) was coated and dried. GD H was bridged and fixed to form the anode electrode.

[0063] (Evaluation of battery) The above cathode electrode, anode electrode, variable resistor, and potentiostat were connected, and open circuit potential measurement was performed. The solution was the same as that used for the evaluation of the cathode electrode, and a glucose solution was added to a final concentration of 10 mM. As a result, the open circuit voltage was + 0.66 V, and a current density of 0.15 mA / cm was obtained when connected to 10 kΩ. 2

[0064] [Example 6] A 0.5 mm square carbon cloth coated with Ketjen black ECP600JD prepared in Example 4 was coated with 20 μl of bovine liver-derived catalase (manufactured by Tokyo Chemical Industry Co., Ltd.) at a final concentration of 5 mg / ml and 5 % glutaraldehyde solution, and dried at room temperature for 2 hours to fabricate an electrode.

[0065] (Electrochemical measurement) Using the above electrode as the working electrode, CV measurement was performed in the same manner as in Example 1. As a result of comparing the cyclic voltammograms before and after the addition of hydrogen peroxide solution, a higher reduction current was observed when the hydrogen peroxide solution was added than when it was not added at a potential of about +600 mV (vs. Ag / AgCl) or lower. At +200 mV (vs. Ag / AgCl), a reduction current 200 μA / cm higher was observed when the hydrogen peroxide solution was added than when it was not added. 2

[0066] [Example 7] ​​​​Spread 20 μl of POD and 5% glutaraldehyde solution onto the mixture and allow to dry at room temperature for 2 hours. The electrodes were then fabricated.

[0067] (Electrochemical measurement) Using the above electrode as the working electrode, CV measurement was performed in the same manner as in Example 1. However, as the substrate Instead of hydrogen peroxide solution, a sodium L-lactate solution was added to achieve a final concentration of 10 mM. The cyclic voltammograms before and after the addition of L-sodium lactate solution were compared, and approximately At potentials of +650mV (vs. Ag / AgCl) or lower, L-sodium lactate solution A higher reduction current was observed when L-sodium lactate solution was added compared to when it was not added. +200mV( In the comparison between Ag / AgCl and L-sodium lactate solution, L-sodium lactate solution was found to be more effective than the solution without L-sodium lactate solution. The current was 140 μA / cm² when the lium solution was added. 2 That was the only high reduction current.

[0068] [Comparative Example] Cathode A do-electrode was fabricated. A multi-walled carbon nanotube dispersion solution was used on a 0.5 mm square carbon cloth. 20 μl of the solution was applied to each side and dried at 60°C for at least 1 hour. Subsequently, the final concentration was 5 mg / m². Apply 20 μl of POD and 5% glutaraldehyde solution, and allow to dry at room temperature for 2 hours. Electrodes were fabricated using [the following method].

[0069] (Electrochemical measurement) Using the above electrode as the working electrode, CV measurement was performed in the same manner as in Example 1. Hydrogen peroxide solution was added. Comparing the cyclic voltammograms before and after the addition, the change was from +200mV to +700mV. No difference in reduction current was observed in the range of (vs. Ag / AgCl).

[0070] Non-patent document 3 describes using GOD for the anode and cathode, and POD for the cathode. It describes a biofuel cell. The open-circuit voltage of the battery in Non-Patent Document 3 is +0.45V. Approximately 0.02mA / cm² when connected to approximately 10kΩ. 2 The current density was approximately [value missing]. The redox potential of the mediator used in the anode electrode was approximately -0.05V. Generally, the lower the redox potential of the anode electrode, the lower the redox potential of the cathode electrode. The difference becomes larger, and as a result the open-circuit voltage increases, which is expected to improve the battery's performance. It can be inferred. Therefore, in the battery of this disclosure, compared to the battery disclosed in Non-Patent Document 3, oxidation Despite using an anode electrode with a fixed IPPD having a reduction potential of +0.1V, In other words, despite being at such a disadvantage, the above output was obtained. The disclosed cathode electrode can be said to have better performance compared to conventional ones. The cathode electrode is fixed to the anode electrode, which has a mediator with an oxidation-reduction potential of -0.05V. It is believed that even greater output can be obtained when combined with poles. [Industrial applicability]

[0071] The cathode electrode of this disclosure can be used in batteries, such as fuel cells, and can also be used for power generation. It is possible.

Claims

1. A cathode electrode combining a reductase enzyme and amorphous carbon.

2. The electrode according to claim 1, wherein the oxidase is further immobilized.

3. The electrode according to claim 2, wherein the oxidase produces hydrogen peroxide as a reaction product. 。

4. Any one of claims 1 to 3, wherein the reductase is catalase or peroxidase. The electrodes described above.

5. Claims 2 to 4, wherein the oxidase is glucose oxidase or lactate oxidase The electrode described in any one of the items.

6. The conductive carbon black is conductive carbon black as described in any one of claims 1 to 5. very.

7. The conductive carbon black is produced by a thermal decomposition method or an incomplete combustion method, claim. The electrode described in 6.

8. A battery having a cathode electrode and an anode electrode according to any one of claims 1 to 7.

9. The battery according to claim 8, having an anode electrode on which an enzyme is immobilized.

10. Cathode electrode, anode electrode, fuel tank, and electrolytic cell according to any one of claims 1 to 7 A fuel cell possessing quality.

11. A method for generating power using a battery according to any one of claims 8 to 10.