JP7293624B2 - Catalyst for positive electrode of enzyme battery, electrode paste composition for positive electrode of enzyme battery, and use thereof - Google Patents

Description

The present invention relates to an enzyme battery positive electrode catalyst, an enzyme battery positive electrode paste composition, an enzyme battery positive electrode, an enzyme battery, a self-power generation sensor, an organic substance sensor, and a moisture sensor.

Enzyme batteries, which are currently under development, are power-generating devices that utilize the electrical energy of electrons generated by enzymatic reactions using organic substances such as sugars, alcohols, and organic acids as fuel.
In recent years, in addition to using the electrical energy extracted from the enzyme battery as a power source, a method has been proposed that utilizes the substrate selectivity of enzymes as a self-powered sensor for sensing organic substances such as sugars and alcohols. ing. Since the self-powered sensor has both power generation and organic substance sensing functions, it is possible to reduce the size, weight, and cost by eliminating the need for a power supply.In addition, it features high sensing accuracy derived from minute amount detection by enzymes and high substrate selectivity. becomes. Therefore, it is expected to be used as a power supply for sensors used in wearable devices and implant devices for living bodies.
On the other hand, the enzyme cell contains redox enzymes in the anode and cathode, and is an energy system that generates electricity using a wide variety of organic substances and oxygen in the air as fuel. While there are multiple advantages, such as high safety, there are also challenges related to output stability, lifespan, cost, and the like.

Various measures have been taken so far to solve the above problems. For example, in order to improve the power generation performance, a porous enzymatic fuel cell using porous carbon (Patent Document 1) and a method of preparing electrodes using a hydrophilic binder to improve the penetration of the enzyme solution (Patent Document 2) ), and a method of providing a protective film between the electrode and the electrolyte membrane to mitigate deactivation of the enzyme due to contact with the acidic group of the electrolyte (Patent Document 3), photocurable A method of suppressing the elution of an enzyme using a resin (Patent Document 4) and the like have been reported. However, it cannot be said that the improvement in performance is low, the application is limited, and so on. Furthermore, since enzymes generally have low resistance to electric potential, there is a known method of replacing the enzyme on the positive electrode side with a noble metal catalyst such as platinum in order to improve durability in order to address the problem of low durability in use. . However, in an enzyme cell that uses a biological sample or biomass containing a large amount of impurity components as fuel, these impurities may poison the positive electrode catalyst and induce a decrease in activity or an unstable output. In addition, the use of expensive noble metals raises the problem of high device costs.
Although various efforts have been made as described above, it is difficult to say that problems related to output stability, service life, cost, etc. have been resolved at present.

JP 2009-181889 A WO2013/065581 JP 2015-109188 A Patent No. 5181576

An object of the present invention is to provide a carbon catalyst that constitutes a positive electrode for an enzyme battery. An object of the present invention is to provide an enzyme battery having a long life and excellent output stability by using the positive electrode for an enzyme battery of the present invention.

As a result of earnest research in order to solve the above-mentioned problems, the inventor has arrived at the present invention.
That is, the present invention provides a carbon catalyst for an enzyme cell positive electrode comprising a carbon material having a carbon hexagonal mesh plane as a basic skeleton, containing a hetero element as a constituent element, wherein the hetero element is at least part of the carbon element in the carbon skeleton. The present invention relates to carbon catalysts for enzyme cell positive electrodes that are substitutively doped and have oxygen reduction activity.

The present invention also relates to the above carbon catalyst for an enzyme battery positive electrode, wherein the hetero element is a nitrogen element.

Further, the molar ratio of nitrogen atoms to all elements on the catalyst surface measured by X-ray photoelectron spectroscopy (XPS) is N, and the N1 type nitrogen obtained by peak separation of the N1s spectrum of XPS with respect to the total nitrogen amount on the catalyst surface When the total (%) of the atomic weight ratio and the N2 type nitrogen atomic weight ratio is (N ₁ + N ₂ ), the surface terminal nitrogen ratio {N × (N ₁ + N ₂ )} is 0.5 to 25.0% It relates to the carbon catalyst for the positive electrode of the enzyme battery characterized by:

Furthermore, the present invention relates to the above carbon catalyst for an enzyme battery positive electrode, which contains a base metal element as a constituent element.

The present invention also relates to the carbon catalyst for the positive electrode of an enzyme battery, characterized in that the base metal element is Co and/or Fe.

Further, when the molar ratio of carbon atoms and the molar ratio of nitrogen atoms to all elements constituting the carbon catalyst are R _C and R _N , respectively, the above enzyme has a ratio of R _N to R _C of 1 to 40% The present invention relates to carbon catalysts for battery positive electrodes.

Also, when the molar ratio of carbon atoms, the molar ratio of nitrogen atoms, and the molar ratio of base metal atoms to all the elements constituting the carbon catalyst are represented by R _C , R _N , and R _M , respectively, the ratio of R _N to R _C is 1 to 40%, and the ratio of _RM to _RC is 0.01 to 20%.

The present invention also relates to the carbon catalyst for the positive electrode of an enzyme cell, characterized in that the BET specific surface area (BET _N2 ) with nitrogen as an adsorbing species is 50 to 1200 m ² /g.

In addition, in an X-ray diffraction diagram obtained using CuKα rays as an X-ray source, the diffraction angle (2θ) has a peak at a position of 24.0 to 27.0°, and the half width of the peak is 8° or less. The present invention relates to the carbon catalyst for the positive electrode of an enzyme battery characterized by:

The present invention also relates to an enzyme battery positive electrode paste composition comprising the carbon catalyst for an enzyme battery positive electrode, at least a solvent, and a binder.

Further, the present invention relates to the above electrode paste composition for an enzyme battery positive electrode, which contains a dispersant.

The present invention also relates to a positive electrode for an enzyme battery having a coating film formed from the electrode paste composition for a positive electrode for an enzyme battery.

The present invention also relates to an enzyme battery formed using the positive electrode for an enzyme battery.

The present invention also relates to a self-power-generating sensor formed using the positive electrode for an enzyme battery.

The present invention also relates to an organic sensor formed using the positive electrode for an enzyme battery.

It also relates to a moisture sensor formed using the enzyme battery.

The present invention also relates to the above enzyme battery, wherein the fuel is at least one selected from the group consisting of glucose, lactic acid and fructose.

The present invention also relates to the above self-power generation sensor, wherein the fuel and/or sensing object is at least one selected from the group consisting of glucose, lactic acid, and fructose.

The present invention also relates to the organic matter sensor, wherein the sensing target is at least one selected from the group consisting of glucose, lactic acid, and fructose.

An object of the present invention is to provide a carbon catalyst for an enzyme battery positive electrode that constitutes a positive electrode for an enzyme battery. By using the positive electrode for an enzyme battery of the present invention, it is possible to provide an enzyme battery and a power-generating sensor having a long life and excellent output stability.

FIG. 1 is a diagram showing oxidation current responsiveness to glucose concentration of positive electrode for enzyme battery (1) (Example 1). FIG. 2 is a diagram showing the ratio of the maximum output of ultrapure water in enzyme cells (1) to (4) to the maximum output of 0.1 M glucose solution in enzyme cell (4). FIG. 3 is a block diagram of a wireless communication circuit using an enzyme battery (5). FIG. 4 is a diagram showing oxidation current responsiveness to lactic acid concentration of the positive electrode (1) for an enzyme battery.

The present invention will be described in detail below. In this specification, the "electrode paste composition for the positive electrode of the enzyme battery" may be simply referred to as the composition. Also, "resin" may be referred to as "polymer". In addition, the "carbon catalyst for the positive electrode of the enzyme battery" may be simply referred to as "carbon catalyst".

<Carbon catalyst for positive electrode of enzyme battery>
The carbon catalyst for the positive electrode of the enzyme battery consists of a carbon material with a basic skeleton of a carbon hexagonal mesh plane that forms a mesh plane in which carbon atoms are covalently bonded in a hexagonal mesh. It is a catalyst material having action (bonding), heteroatoms such as heteroatoms such as N, B, P, etc., optionally containing base metal elements, and having oxygen reduction activity. The base metal element referred to here is a metal element excluding noble metal elements (ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, gold) among transition metal elements. Examples of base metal elements include cobalt, iron, nickel, It preferably contains 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 is significant in terms of oxygen reduction activity. The carbon catalyst for the positive electrode of the enzyme cell has, as its catalytic active point, for example, a nitrogen atom doped so as to replace the carbon element at the edge of the carbon hexagonal network plane constituting the basic skeleton of the carbon catalyst, or a carbon atom in the vicinity thereof. , and nitrogen atoms and base metal atoms in a base metal-N4 structure in which four nitrogen atoms are aligned on a plane around a base metal element on the surface of the catalyst.

It is preferable that the carbon catalyst for an enzyme battery positive electrode in the present invention has a large specific surface area and high electron conductivity. Since the oxygen reduction reaction occurs on the surface of the catalyst, the larger the specific surface area, the greater the number of reaction fields between oxygen, protons, and electrons, which leads to an improvement in catalytic activity, which is preferable. In addition, the higher the electron conductivity, the more electrons necessary for the oxygen reduction reaction in the electrode can be supplied to the reaction field, which is preferable because it tends to lead to an increase in current. In addition, the larger the amount of heteroatoms, particularly nitrogen, on the surface of the catalyst is, the more the number of active sites on the surface tends to increase.

When the molar ratio of carbon atoms, the molar ratio of nitrogen atoms, and the molar ratio of base metal atoms to all the elements constituting the catalyst are represented by R _C , R _N , and R _M , respectively, in the carbon catalyst for an enzyme battery positive electrode in the present invention, , the ratio of the molar ratio R _N of nitrogen atoms to the molar ratio R _C of carbon atoms is 1 to 40%, and the ratio of the molar ratio R _M of base metal atoms to the molar ratio R _C of carbon atoms is in the range of 0.01 to 20%. It is preferable to be in More preferably, the ratio of the molar ratio R _N of nitrogen atoms to the molar ratio R _C of carbon atoms is 1.5 to 20%, and the ratio of the molar ratio R _M of base metal atoms to the molar ratio R _C of carbon atoms is 0.05. ~10%.

When the elemental ratio of nitrogen atoms and base metal atoms to carbon atoms is within the above range, the base metal element is effective as a carbonization catalyst for promoting crystallization of carbon, developing pores, generating edges, etc. in the active site formation stage. It can be expected to improve the number and quality of active sites by acting on Furthermore, in the oxygen reduction catalytic reaction stage, the metal species act as a reduction catalyst for hydrogen peroxide generated mainly at nitrogen-derived active sites, effectively promoting reduction to water (four-electron reduction). It is preferable because it can be expected that

In addition, the molar ratio of nitrogen atoms to all elements on the catalyst surface measured by X-ray photoelectron spectroscopy (XPS) is defined as (N), and N1 obtained by peak separation of the N1s spectrum of XPS with respect to the total nitrogen amount on the catalyst surface When the sum (%) of the ratio of type nitrogen atomic weight and the ratio of N2 type nitrogen atomic weight is (N ₁ + N ₂ ), the surface terminal nitrogen ratio {N × (N ₁ + N ₂ )} is 0.5 to 25% is preferably More preferably 1 to 18%.

For example, the molar ratio N of nitrogen atoms to all elements on the catalyst surface is 0.1, the ratio _N1 of N1-type nitrogen atoms to the total nitrogen amount on the catalyst surface, which is obtained by peak separation of the N1s spectrum of XPS, is 30%, N2 In the case of a carbon catalyst for an enzyme battery positive electrode having a type nitrogen atomic weight ratio N ₂ of 20%, the surface terminal nitrogen ratio is 5% according to the following formula.
{N x ( _N1 + _N2 )} = 0.1 x (30% + 20%) = 5%

As shown in the structural formula below, the nitrogen atoms in the carbon catalyst for the positive electrode of the enzyme battery are present in various states so as to substitute the carbon elements in the carbon hexagonal mesh plane. In the present invention, the N1-type nitrogen atom has an N1s electron binding energy of 398.5±0.5 eV and has a pyridine-like structure. The N2-type nitrogen atom has an N1s electron binding energy of 400±0.5 eV and has a pyrrole-like structure. These are called pyridine N and pyrrole N, respectively, and are collectively called terminal nitrogen in the present invention. If these peaks overlap each other, the peaks are separated by fitting by optimizing each component as a Gaussian function with the peak intensity, peak position, and peak full width at half maximum as parameters. Here, since it is difficult to separate the peaks of those having a pyridone-like structure, for the sake of convenience, they may be included in the terminal nitrogen.
Nitrogen atoms other than the above include N3-type nitrogen atoms (mainly existing in the interior of a carbocyclic ring, quaternary ones bonded to three carbon atoms), N4-type nitrogen atoms (in an oxidized state, are combined with heterogeneous elements).

The terminal nitrogen has a lone pair of electrons, and the terminal nitrogen affects the electronic state of the surrounding carbon, and in addition to the adjacent carbon atoms acting as active sites, the nitrogen atoms are coordinated to the base metal. It has been reported to favor base metal-N4 structure formation. Therefore, it is considered that a large amount of terminal nitrogen exists on the surface of a highly active catalyst, and the surface terminal nitrogen ratio is an index representing the amount of terminal nitrogen present on the surface.

The carbon catalyst for the positive electrode of an enzyme battery in the present invention preferably has a BET specific surface area (BET _N2 ) with nitrogen as an adsorbing species of 50 to 1200 m ² /g. When the BET specific surface area is within the above range, it is preferable because the reaction field in which the reaction occurs can be increased. More preferably 100 to 1000 m ² /g.

The specific surface area in the present invention means the surface area per unit mass of sample, and can be obtained by gas (N ₂ or H ₂ O) adsorption method. The analysis method uses the BET method, and from the intercept and slope of the straight line obtained by plotting the relative pressure (P (adsorption equilibrium pressure) / P0 (saturated vapor pressure) = 0.05 to 0.3) and the amount of gas adsorption, the simple By obtaining the molecular adsorption amount, the BET specific surface area can be calculated.

The carbon catalyst for an enzyme battery positive electrode in the present invention has a peak at a diffraction angle (2θ) of 24.0 to 27.0° in an X-ray diffraction (XRD) diagram obtained using CuKα rays as an X-ray source. , the half width of the peak is preferably 8° or less.

In the X-ray diffraction diagram of the carbon catalyst for positive electrode of an enzyme battery obtained using CuKα rays as an X-ray source, the (002) plane diffraction peak of carbon appears at around 24.0 to 27.0°. The position of the (002) diffraction peak of carbon varies depending on the interplanar distance of the hexagonal carbon planes, and the higher the angle of the peak position, the closer the distance between the hexagonal carbon planes. is shown. The sharper the peak (the smaller the half-value width), the larger the crystallite size and the more developed the crystal structure.

When the half width of the peak is 8° or less, the carbon catalyst for the positive electrode of the enzyme battery has high crystallinity and high electron conductivity. As a result, the electrons necessary for the oxygen reduction reaction in the electrode can be supplied to the reaction field, which leads to an increase in current, which is preferable.

Further, it is more preferable that the half width of the peak is 1° or less.

Cobalt (Co) and/or iron (Fe) are preferable as base metals to be contained because they have a strong function for the above-mentioned catalytic action.

<Method for producing carbon catalyst for positive electrode of enzyme battery>
The method for producing the carbon catalyst in the present invention is not particularly limited,
A method of mixing and carbonizing a carbonaceous raw material, a compound containing a hetero element and a compound containing a base metal element,
A method of mixing and carbonizing a carbonaceous raw material and a compound containing a hetero element,
A method of mixing and carbonizing a carbonaceous raw material containing a hetero element and a compound containing a base metal element,
A method of carbonizing a compound containing heteroelements and base metal elements such as macrocyclic compounds such as phthalocyanines and porphyrins,
A method of mixing and carbonizing a carbonaceous raw material and a compound containing a hetero element and a base metal element,
A method of doping a hetero element in a material obtained by mixing and carbonizing a carbonaceous raw material and a compound containing a base metal element by a vapor phase method,
A conventionally known method such as a method of doping a carbon-based raw material with a hetero element by a vapor phase method can be used.
Preferred production methods include a method of mixing a carbon-based raw material containing at least a hetero element and a compound containing a base metal element and heat-treating the mixture, or a method of mixing at least a carbon-based raw material with a compound containing a hetero element and a base metal element, A method of heat treatment is mentioned. Moreover, the method includes the steps of washing the carbon catalyst obtained by the heat treatment with an acid and drying it. Furthermore, there is a method including a step of heat-treating the carbon catalyst obtained by the acid washing.

<Carbon-based raw material>
An inorganic carbon-based raw material is preferable as the carbon-based raw material for producing the carbon catalyst for the positive electrode of the enzyme battery in the present invention. Examples include carbon black (furnace black, acetylene black, ketjen black, medium thermal carbon black), activated carbon, graphite, carbon nanotubes, carbon nanofibers, carbon nanohorns, graphene, graphene nanoplatelets, nanoporous carbon, carbon fibers, and the like. be done. Among the above inorganic carbon-based raw materials, the size and lamination structure of the carbon hexagonal network surface vary depending on the type and manufacturer, and the crystallinity, particle diameter, shape, BET specific surface area, pore volume, pore diameter, bulk density, DBP oil absorption, etc. Since various physical properties such as amount, surface acid-basicity, surface hydrophilicity, conductivity, etc. and cost are different, the optimum material can be selected according to the application and required performance.

Commercially available inorganic carbon-based raw materials include, for example,
Ketjenblack manufactured by Lion Specialty Chemicals such as Ketjenblack EC-300J, EC-600JD, Lionite EC-200L;
Furnace blacks manufactured by Tokai Carbon Co., Ltd. such as Toka Black #4300, #4400, #4500, and #5500;
Degussa furnace black such as Printex L;
Columbian furnace blacks such as Raven 7000, 5750, 5250, 5000 ULTRA III, 5000 ULTRA, Conductex SC ULTRA, 975 ULTRA, PUER BLACK 100, 115, and 205;
Mitsubishi Chemical Furnace Blacks such as #2350, #2400B, #2600B, #3050B, #3030B, #3230B, #3350B, #3400B, and #5400B;
Cabot furnace blacks such as MONARCH 1400, 1300, 900, Vulcan XC-72R, and BlackPearls 2000;
TIMCAL furnace blacks such as Ensaco 250G, Ensaco 260G, Ensaco 350G, 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, and 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, xGnP- XGSciences graphene nanoplatelets such as H-25;
Nanoporous carbon manufactured by Easy-N;
Carbon fibers manufactured by Gun Ei Chemical Industry Co., Ltd., such as Kynor carbon fiber and Kynor activated carbon fiber;
Knobel MH grade, Knobel P(2) 010 grade, Knobel P(3) 010 grade, Knobel P(4) 050 grade, Knobel MJ(4) 030 grade, Knobel MJ(4) 010 grade, Knobel MJ(4) 150 Grades such as Knobel manufactured by Toyo Tanso Co., Ltd., but are not limited to these.

As the carbon-based raw material for producing the carbon catalyst in the present invention, not only an inorganic carbon-based raw material but also an organic carbon-based raw material that becomes carbon particles after heat treatment can be used. The organic material that becomes carbon particles after heat treatment may contain other elements besides carbon. In some cases, it is preferable to use an organic material containing such a hetero element in advance in order to make the carbon particles after the heat treatment contain a hetero element such as nitrogen or boron, which becomes an active site. Specific organic materials include phenol-based resins, polyimide-based resins, polyamide-based resins, polyamide-imide-based resins, polyacrylonitrile-based resins, polyaniline-based resins, phenol-formaldehyde-based resins, polyimidazole-based resins, polypyrrole-based resins, poly Benzimidazole-based resins, melamine-based resins, pitch, lignite, polycarbodiimide, biomass, proteins, humic acid, and derivatives thereof, and the like. Among them, polyimide-based resin, polyamide-based resin, polyamideimide-based resin, polyacrylonitrile-based resin, polyaniline-based resin, etc., which are organic materials containing hetero elements such as nitrogen and boron, are organic carbon-based raw materials because they contain nitrogen elements. is preferred.

<Compound containing hetero element and/or base metal element>
As a carbon catalyst in the present invention, the raw material used when introducing a hetero element or a base metal element is not particularly limited as long as it is a compound containing a hetero element and/or a base metal element. Examples include organic compounds such as dyes and polymers, and inorganic compounds such as elemental metals, metal oxides and metal salts. Moreover, one type may be used alone, or two or more types may be used in combination. Base metal elements are transition metal elements excluding noble metal elements (ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, and gold). Base metal elements include cobalt, iron, nickel, manganese, and copper. , titanium, vanadium, chromium, zinc and tin.
A complex or a salt is preferable, and among them, a nitrogen-containing aromatic compound capable of containing a base metal element in the molecule facilitates efficient introduction of the nitrogen element and the base metal element into the carbon catalyst. preferable. Specific examples include macrocyclic compounds such as phthalocyanine-based compounds, naphthalocyanine-based compounds, porphyrin-based compounds, and tetraazaannulene-based compounds. The aromatic compound may be one into which an electron-withdrawing functional group or an electron-donating functional group has been introduced. In particular, phthalocyanine-based compounds are particularly preferable as raw materials because compounds containing various base metal elements are available and are inexpensive. Among them, cobalt phthalocyanine-based compounds, nickel phthalocyanine-based compounds, and iron phthalocyanine-based compounds are known to have high oxygen reduction activity. It is more preferable because a catalyst can be obtained.

A combination of a plurality of raw materials can be considered as the origin of the elements introduced into the carbon catalyst. A carbon element is an inorganic carbon-based raw material, an organic carbon-based raw material, a hetero element and / or a compound containing a base metal element. A base metal element is a hetero element and/or a compound containing a base metal element, such as a compound containing a base metal element, a reactive gas containing a hetero element such as ammonia, or the like. The raw material from which the element to be introduced may be a single element or a mixture of multiple types of the same element.
Examples of raw material combinations include:
The carbon element is an inorganic carbon-based raw material, the hetero element is a carbon catalyst derived from the hetero element doping of the vapor phase method,
The carbon element is an organic carbon-based raw material, the hetero element is a carbon catalyst derived from the hetero element dope of the vapor phase method,
A carbon catalyst derived from an organic carbon-based raw material containing a carbon element and a hetero element, and at least one hetero element;
A carbon catalyst derived from a compound containing a hetero element and/or a base metal element, wherein the carbon element is an inorganic carbon-based raw material, and the hetero element and the base metal element are at least one type or more, respectively.
A carbon catalyst derived from a compound containing a hetero element and/or a base metal element, wherein the carbon element is an organic carbon-based raw material, and the hetero element and the base metal element are at least one or more of each of the hetero element and the base metal element,
The carbon element is an organic carbon-based raw material, the hetero element is a compound containing a hetero element and/or a base metal element that does not contain a base metal element and contains at least one type of hetero element, and the base metal element is at least a base metal element that does not contain a hetero element A carbon catalyst derived from a compound containing a hetero element and/or a base metal element, including one or more
An organic carbon-based raw material containing a carbon element and a hetero element, at least one hetero element, a carbon catalyst derived from a compound containing a hetero element and / or a base metal element, containing at least one base metal element,
A carbon catalyst derived from a compound containing a carbon element, a hetero element and a base metal element, which contains at least one carbon element and at least one hetero element and base metal element,
A carbon catalyst derived from a compound containing a hetero element and/or a base metal element, which contains an inorganic carbon-based raw material as a carbon element, and at least one hetero element and a base metal element, and the like.

As a method for producing a precursor that is a mixture of raw materials, a carbon-based raw material and one or more types of hetero elements and/or base metal elements are contained so that the precursor contains a carbon element, a hetero element, and a base metal element. When mixing with the compound to be mixed, it is sufficient that the raw materials are uniformly mixed and compounded, and examples of the mixing method include dry mixing and wet mixing. As a mixing device, a dry mixing device or a wet mixing device as described below can be used.

Examples of dry mixing equipment include roll mills such as two rolls and three rolls, high speed stirrers such as Henschel mixers and super mixers, fluid energy pulverizers such as micronizers and jet mills, attritors, and particle composites manufactured by Hosokawa Micron. Apparatuses such as "NanoCure", "Nobilta", "Mechanofusion", powder surface modification apparatus "Hybridization System", "Mechanomicros", and "Mirraro" manufactured by Nara Machinery Co., Ltd. can be mentioned.

When using a dry mixing apparatus, other raw materials may be directly added in powder form to the base raw material powder. It is preferable to dissolve or disperse the powder in a solvent and add it while loosening the agglomerated particles of the base material powder. Furthermore, heating may be preferred in order to increase processing efficiency.

Among compounds containing heteroelements and/or base metal elements, there are materials that are solid at room temperature but have a low melting point, softening point, or glass transition temperature of less than 100°C. When these materials are used, it may be possible to achieve more uniform mixing by melting and mixing under heating than by mixing at room temperature.

As a wet mixing device, for example,
Mixers such as disper, homomixer, or planetary mixer;
Homogenizers such as "Clairmix" manufactured by M Technic Co., Ltd. or "Filmix" manufactured by PRIMIX;
Paint conditioner (manufactured by Red Devil), ball mill, sand mill (such as "Dyno Mill" manufactured by Shinmaru Enterprises), attritor, pearl mill (such as "DCP Mill" manufactured by Eirich), or media-type dispersing machine such as a coball mill;
Wet type jet mill ("Genus PY" manufactured by Genus, "Starburst" manufactured by Sugino Machine, "Nanomizer" manufactured by Nanomizer, etc.), "Crea SS-5" manufactured by M Technic, or "Micro medialess disperser such as
Alternatively, roll mills, kneaders, etc. may be used, but are not limited to these. As the wet mixing device, it is preferable to use one subjected to treatment to prevent metal contamination from the device.

For example, when using a media-type disperser, a disperser whose agitator and vessel are made of ceramic or resin, or a disperser whose metal agitator and vessel surface are treated with tungsten carbide spraying or resin coating. is preferably used. As 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 dispersing device may be used, or a plurality of types of devices may be used in combination.

In addition, when each raw material is not uniformly dissolved in a system, in order to improve the wettability and dispersibility of each raw material in a solvent, a general dispersant such as a water-based dispersant or a solvent-based dispersant is added together. can be dispersed and mixed.

<Aqueous Dispersant>
Commercially available aqueous dispersants include, but are not limited to, the following.

Dispersants manufactured by BYK-Chemie include DISPERBYK-180, 184, 187, 190, 191, 192, 193, 194, 199, 2010, 2012, 2015, 2096 and the like.

Dispersants manufactured by Lubrizol Japan include SOLSPERSE 12000, 20000, 27000, 41000, 41090, 43000, 44000, or 45000.

Dispersants manufactured by BASF Japan include JONCRYL67, 678, 586, 611, 680, 682, 683, 690, 60, 61, 62, 63, HPD-96, Luvitec K17, K30, K60, K80, K85, K90. , VA64, and the like.

Dispersants manufactured by Kawaken Fine Chemicals Co., Ltd. include Hinoact A-110, 300, 303, and 501.

Dispersants manufactured by Nittobo Medical Co., Ltd. include PAA series, PAS series, amphoteric series PAS-410C, 410SA, 84, 2451, and 2351.

Dispersants manufactured by ISP Japan include polyvinylpyrrolidone PVP K-15, K-30, K-60, K-90, K-120, and the like.

Dispersants manufactured by Maruzen Petrochemical Co., Ltd. include polyvinylimidazole PVI and the like.

<Dispersant for solvent system>
Commercially available solvent-based dispersants include, but are not limited to, the following.

Dispersants manufactured by BYK Chemie include Anti-Terra-U, U100, 204, DISPERBYK-101, 102, 103, 106, 107, 108, 109, 110, 111, 140, 161, 163, 168, 170, 171. etc.

Dispersants manufactured by Nippon Lubrizol include SOLSPERSE 3000, 5000, 9000, 13240, 13650, 13940, 17000, 18000, 19000, 21000, 22000, 24000SC, 24000GR, 26000, 28000, 31845, 32000, 32 500, 32600, 33500 , 34750, 35100, 35200, 36600, 37500, 38500, or 53095.

Dispersants manufactured by Ajinomoto Fine-Techno Co., Inc. include Ajisper PB821, PB822, PN411, or PA111.

Dispersants manufactured by Kawaken Fine Chemicals include Hinoact KF-1000, 1300M, 1500, T-6000, 8000, 8000E and 9100.

Luvicap etc. are mentioned as a dispersing agent by BASF Japan.

In the case of wet mixing, a step of drying the dispersion produced using a wet mixing apparatus is required. In this case, the drying apparatus used includes a tray dryer, a rotary dryer, a flash dryer, a spray dryer, a stirring dryer, a freeze dryer, and the like.

In the method for producing a carbon catalyst, by selecting an optimum mixing device, dispersing device, or drying device for a compound containing a carbonaceous raw material and a hetero element and/or a base metal element, carbon with excellent catalytic activity is produced. A catalyst can be obtained.

Next, in the method of heat-treating a mixture of a carbonaceous raw material and a compound containing a hetero element and/or a base metal element, it varies depending on the carbonaceous raw material used as the raw material and the compound containing the hetero element and/or the base metal element. The heating temperature is preferably 500-1100°C, more preferably 700-1000°C.
In this case, by heat-treating at a relatively high temperature, nitrogen atoms are doped so as to replace the carbon elements at the edges of the carbon hexagonal network surface, the structure of the active sites is stabilized, and it can withstand practical battery operating conditions. It often becomes the surface of the catalyst. The temperature at this time is preferably 600° C. or higher.

Although the heating time is not particularly limited, it is usually preferably from 1 hour to 5 hours.

Furthermore, regarding the atmosphere in the heat treatment process, it is necessary to carbonize the raw material by incomplete combustion as much as possible and leave the hetero element and metal element on the surface of the carbon catalyst. or a reducing gas atmosphere in which hydrogen is mixed with argon. In addition, in order to suppress the reduction of the amount of hetero elements in the carbon catalyst during heat treatment, the heat treatment is performed in an ammonia gas atmosphere containing a large amount of nitrogen element, and in order to control the surface structure of the carbon catalyst, water vapor, carbon dioxide , the heat treatment may be performed in a low-oxygen atmosphere. In this case, depending on the atmosphere, if the oxidation progresses, the metal becomes an oxide and the particle components tend to aggregate, so it is necessary to appropriately select the temperature, time, and the like.

Regarding the heat treatment process, in addition to the method of performing treatment in one step under a constant atmosphere and temperature, heat treatment is performed once at a relatively low temperature of about 500 ° C. in an inert gas atmosphere, and then an inert gas is used. It is also possible to heat-treat at temperatures above the first step in atmosphere, in a reducing gas atmosphere, or in an activating gas atmosphere. By doing so, active site sites composed of hetero elements and metal elements, which are considered as catalytic active sites, may be left more efficiently and in large amounts.

Examples of the method for producing the carbon catalyst further include a method including the steps of washing the carbon catalyst obtained by the heat treatment with an acid and drying. The acid used here is not particularly limited as long as it can dissolve base metal components that do not act as active sites present on the surface of the carbon catalyst obtained by the heat treatment. Preferred are concentrated hydrochloric acid, dilute sulfuric acid, and the like, which have low reactivity with the carbon catalyst and strong dissolving power for base metal components. As a specific washing method, an acid is added into a glass container, a carbon catalyst is added, the mixture is stirred for several hours while being dispersed, and then the mixture is allowed to stand and the supernatant is removed. Then, the above method is repeated until the supernatant is no longer colored, and finally, the acid is removed by filtering and washing with water, followed by drying.
A carbon catalyst having a carbon element in the vicinity of a nitrogen element at the edge portion as a catalytically active site is preferable because the base metal component on the surface is removed by washing with an acid, thereby improving the catalytic activity.

The method for producing the carbon catalyst further includes a step of subjecting the carbon catalyst obtained by the acid washing to heat treatment again. The heat treatment here is not much different from the conditions of the previous heat treatment. The heating temperature is preferably 500-1100°C, more preferably 700-1000°C. In addition, from the viewpoint that the nitrogen element on the surface is difficult to decompose and decrease, the atmosphere is an inert gas atmosphere such as nitrogen or argon, a reducing gas atmosphere in which hydrogen is mixed with an inert gas, or an atmosphere of ammonia containing a large amount of nitrogen element. A gas atmosphere or the like is preferable.

<Electrode paste composition for positive electrode of enzyme battery>
The electrode paste composition for an enzyme battery positive electrode contains a carbon catalyst for an enzyme battery positive electrode, at least a solvent, and a binder, and the active points are exposed without covering the entire surface of the enzyme battery positive electrode carbon catalyst with a resin (binder). Therefore, the active sites can effectively function for the desired catalytic reaction.

Moreover, the electrode paste composition for an enzyme battery positive electrode contains a dispersing agent as needed. The ratio of the carbon catalyst for the positive electrode of the enzyme battery, the solvent, the binder, and the dispersant is not particularly limited, and can be appropriately selected within a wide range.

<Solvent>
The solvent used in the present invention is not particularly limited and can be used. If necessary, a plurality of solvent species may be mixed and used, for example, in order to improve dispersibility and coatability onto a conductive support. Solvents include alcohols, glycols, cellosolves, amino alcohols, amines, ketones, carboxylic acid amides, phosphoric acid amides, sulfoxides, carboxylic acid esters, phosphoric acid esters, ethers, nitriles and water. Among them, water and alcoholic solvents having 4 or less carbon atoms are preferable.

<Binder>
The binder in the present invention is used to bind particles such as the carbon catalyst for the positive electrode of the enzyme battery, and the effect of dispersing the particles in the solvent is small.
Conventionally known binders can be used, for example, acrylic resins, polyurethane resins, polyester resins, phenol resins, epoxy resins, phenoxy resins, urea resins, melamine resins, alkyd resins, formaldehyde resins, silicone resins, Fluororesins, synthetic rubbers such as styrene-butadiene rubbers and fluororubbers, conductive resins such as polyaniline and polyacetylene, and polymer compounds containing fluorine atoms such as polyvinylidene fluoride, polyvinyl fluoride, perfluorocarbons and tetrafluoroethylene. be done. Modified products, mixtures or copolymers of these resins may also be used. These binders can also be used singly or in combination.

Also, when using an aqueous liquid medium, a binder, commonly called an aqueous emulsion, can also be used. An aqueous emulsion is one in which a binder resin is not dissolved in water but dispersed in the form of fine particles.

Although the emulsion to be used is not particularly limited, (meth)acrylic emulsion, nitrile emulsion, urethane emulsion, diene emulsion (SBR (styrene butadiene rubber), etc.), fluorine emulsion (PVDF (polyvinylidene fluoride) and PTFE ( polytetrafluoroethylene), etc.).

<Dispersant>
The dispersant used in the electrode paste composition for the positive electrode of an enzyme battery functions effectively as a dispersant for the carbon catalyst for the positive electrode of an enzyme battery, and can alleviate aggregation. The dispersant is not particularly limited as long as it has the effect of alleviating aggregation of the carbon catalyst for the positive electrode of the enzyme battery.

As the dispersing agent to be used, the dispersing agent for water system, solvent system, etc. exemplified in the method for producing the precursor of the carbon catalyst for the positive electrode of the enzyme cell can be used.

<Disperser/Mixer>
As the apparatus used for obtaining the composition of the present invention, dispersers and mixers commonly used for dispersing pigments and the like can be used.

For example, mixers such as Disper, Homomixer, or Planetary Mixer; Homogenizers such as "Creamix" manufactured by M Technic Co., Ltd. or "Filmix" manufactured by PRIMIX; Paint shaker (manufactured by Red Devil Co., Ltd.), ball mill, sand mill (“Dyno Mill” manufactured by Shinmaru Enterprises Co., Ltd.), attritor, pearl mill (“DCP Mill” manufactured by Eirich Co., etc.), media type dispersing machine such as a coball mill; wet jet mill (“Genus PY” manufactured by Genus Co., Ltd., Sugino "Starburst" manufactured by Machine Co., Ltd., "Nanomizer" manufactured by Nanomizer, etc.), "Crea SS-5" manufactured by M Technic Co., Ltd., or "MICROS" manufactured by Nara Machinery Co., Ltd. Medialess disperser; or other roll mills, etc. Examples include, but are not limited to. Moreover, as the dispersing machine, it is preferable to use a dispersing machine subjected to a treatment to prevent metal contamination from the dispersing machine.

For example, when using a media-type disperser, a disperser whose agitator and vessel are made of ceramic or resin, or a disperser whose metal agitator and vessel surface are treated with tungsten carbide spraying or resin coating. is preferably used. As 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 dispersing device may be used, or a plurality of types of devices may be used in combination.

<Enzyme battery>
The enzyme cell of the present invention is composed of a positive electrode (cathode) and a negative electrode (anode), and generates electrons through an oxidation reaction between an enzyme and a fuel.
<Fuel>
The fuel that can be used in the enzyme battery of the present application is not particularly limited as long as it is an organic substance that can be decomposed by an enzyme. Widely available if available.

<Positive electrode for enzyme battery>
A positive electrode for an enzyme battery receives electrons generated at the anode and consumes them through a reduction reaction in the electrode. As for the structure of the positive electrode for an enzyme battery, for example, in the case of an oxygen reduction reaction using oxygen as an electron acceptor, a conductive path for electrons and protons and an oxygen supply path are secured to the active point of the positive electrode catalyst, which is the reaction site. It is preferable in terms of efficient power generation.
The positive electrode for an enzyme battery can be produced by directly applying the composition to a base material such as a conductive support (carbon paper, a conductive carbon layer, etc.) or a separator and drying the composition, or applying the composition to a transfer base material. It is produced by a method of transferring a coating film formed by applying and drying a material to the conductive support, separator, or the like.
The method of applying the composition is not particularly limited, and examples include knife coaters, bar coaters, blade coaters, sprayers, dip coaters, spin coaters, roll coaters, die coaters, curtain coaters, screen printing, and the like. method can be applied.

<Conductive support>
The conductive support is not particularly limited as long as it is a conductive material. A conductive layer made of a conductive carbon material, carbon paper, carbon felt, carbon cloth, metal foil, metal mesh, or the like is used. The conductive layer is produced by coating a substrate with a conductive paste composition for a conductive carbon layer containing a conductive carbon material.

<Separator>
The separator is not particularly limited as long as it can electrically separate the negative electrode and the positive electrode (prevention of short circuit), and conventionally known materials can be used. Specifically, polyethylene fiber, polypropylene fiber, glass fiber, resin nonwoven fabric, glass nonwoven fabric, felt, filter paper, Japanese paper, and the like can be used.

<Enzyme>
The enzyme in the present invention is not particularly limited as long as it can give and receive electrons by reaction, and is appropriately selected according to the fuel to be supplied, the cost, the type of device, and the like.
The enzyme is preferably an oxidoreductase that catalyzes many redox reactions in vivo such as substance metabolism. In the anode electrode used in the enzyme battery of the present invention, any enzyme that can emit electrons can be used, such as oxidase or dehydrogenase such as sugar or organic acid. Among them, glucose oxidase, which is less expensive than other enzymes, highly stable, and capable of using glucose contained in biological samples such as human blood and urine as fuel, may be preferable. Other enzymes include lactate oxidase and lactate dehydogenase that can use lactic acid in sweat and blood, and fructose oxidase and fructose dehydogenase that can use fructose as fuel.

<Mediator>
Enzymes include direct electron transfer (DET) enzymes that can directly transfer electrons to an electrode and enzymes that cannot directly transfer electrons. In the case of a non-DET enzyme, it is necessary to use a mediator that plays a role in transferring electrons generated by fuel oxidation from the enzyme to the electrode. The mediator is not particularly limited as long as it is a redox substance capable of transferring electrons to the electrode, and conventionally known mediators can be used. Methods of using the mediator include a method of supporting it on an electrode, a method of dissolving it in an electrolytic solution, and the like. Examples of mediators include tetrathiafulvalene, ferrocene, quinones, osmium complexes, and the like.

<Negative electrode for enzyme battery>
In the negative electrode for an enzyme battery, electrons generated by the oxidation reaction of the fuel are supplied to the cathode. The negative electrode for the enzyme battery is a coating film obtained by directly applying the composition to a base material such as a conductive support (carbon paper, a conductive carbon layer, etc.) or a separator and drying it, or applying the composition to a transfer base material. Enzymes and mediators are supported on coating films prepared by transferring coating films formed by drying and transferring to the conductive support, separator, etc., enzymes and mediators are directly supported on conductive supports, It is produced by applying an enzyme battery negative electrode paste composition containing an enzyme to a substrate and drying the substrate.
The method for applying the above composition is not particularly limited, and a general method used for producing a positive electrode for an enzyme battery can be applied.
The method of supporting the enzyme or mediator may be carried out by including it in the above composition, or may be carried out later on the coating film dried after coating or on the conductive support. In the case of carrying out afterward, a method of immersing a liquid in which an enzyme or a mediator is dissolved in the coating film or the conductive support, followed by drying and carrying the solution can be used.

<Sensors, self-powered sensors, organic matter sensors, moisture sensors>
An enzyme cell is a power generation device that utilizes an enzymatic reaction on the anode side to generate electrons and ions from various organic fuels such as sugars, alcohols, and organic acids, and utilizes an oxygen reduction reaction on the cathode side. Therefore, by detecting the presence or absence of power generation and the amount of power generation, it is also possible to use it as a sensor (organic matter sensor) that targets organic matter that serves as fuel.
Furthermore, by driving the sensor using the power generated by the enzymatic reaction, it can be used as a power-free sensor (self-power generation type sensor) that does not require an external power supply. This self-power-generating sensor is included in a type of enzyme battery, and is expected to be used as a power supply for enzyme batteries, as well as wearable and implant sensors for living organisms. When used as a living body device, 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 objects. In addition, even if the biological sample does not contain an organic substance that can be used as a fuel, by incorporating an organic substance that can be used as a fuel into the battery in advance, it is possible to generate electricity using a liquid component such as water. It can also be used as an object sensor (for example, a moisture sensor).
The structure of an enzyme cell includes an anode for oxidizing fuel, a cathode for oxygen reduction, and a separator for separating the anode and cathode. However, if the anode and cathode can be electrically separated, the separator may not necessarily be provided. As the cathode, the enzyme battery positive electrode catalyst and the enzyme battery positive electrode paste composition of the present invention can be suitably used.
It may also contain an ionic conductor for transmitting ions from the anode to the cathode side. Enzyme batteries in the form of fuel and/or ion conductors contained in urine, sweat, blood, etc., which are objects to be sensed, are taken into consideration when used in devices for living organisms, etc. may be preferred.
In the case of an enzyme cell in which the anode and cathode are not completely separated, and in which a non-separator type or paper is used as a separator, impurities contained in the fuel may poison the oxygen reduction catalyst of the cathode reaction. , activity decrease, and output instability are likely to occur, so caution is required. In particular, precious metal catalysts such as platinum are susceptible to poisoning, so their use in the same system is not preferred. On the other hand, since the carbon catalyst for the positive electrode of the enzyme battery used in the present invention is more resistant to poisoning than these noble metal catalysts, it can be suitably used even in systems where impurities are present.
In addition, when the carbon catalyst for the positive electrode of an enzyme battery used in the present invention is used for the cathode of a device manufactured by applying an anode and a cathode directly to an easy-to-dispose separator such as non-woven fabric, felt, or paper, expensive precious metals and It is possible to realize a low-cost, disposable (easy-to-dispose, no-recycle, etc.) device that does not use oxygen reductase.

As described above, the enzyme battery of the present invention functions as a power source using generated power, a self-powered sensor that serves as both a power source and a sensor, an organic substance sensor, a moisture sensor, etc., and these are expected to be used in various applications. . As for usage, a battery of another type (coin battery, etc.) is used as a power supply, the enzyme battery of the present invention is used as a sensor, one or more types of the enzyme battery of the present invention are used as a power supply and a sensor, or the enzyme battery of the present invention is used as a power supply. Enzyme batteries and other types of sensors can be used as sensors.

The power source applications of the enzyme cell in the present invention include, for example, household power sources, power sources for mobile devices, disposable power sources, wearable power sources/implant power sources for living organisms, power sources for biomass fuels, power sources for IoT sensors, and surrounding organic matter as fuel. Examples include energy harvesting power sources that can generate electricity.

Sensor applications include, for example, organic sensors that target various organic substances, biosensors that target organic substances and body fluids in biological samples such as blood, sweat, urine, feces, tears, saliva, and exhaled breath, and sensors that target moisture. food sensors that target sugars in fruits and foods; IoT sensors; environmental sensors that target organic substances in the environment such as air, rivers, and soil; animal and plant sensors that target animals, insects, and plants The above may be a self-power generation type sensor that serves as both a power source and a sensor, or may be used only as a sensor without being used as a power source. Examples of biosensors include a blood sugar sensor that senses sugar in blood, a urine sugar sensor that senses sugar in urine, a fatigue sensor that senses lactic acid in sweat, a heat stroke sensor that senses sweat and urine Examples include a perspiration sensor and a urination sensor that sense moisture inside. Examples of applications as wearable sensors for living organisms include urination sensors, urine sugar level sensors, and skin-attached sensors for perspiration and heatstroke.
As an IoT sensor, it can be used by combining a wireless device and a sensor to wirelessly transmit sensing information to the outside. In that case, the enzyme battery of the present invention can be preferably used.
For example, using an enzyme battery as the power supply and sensor for the radio, using an enzyme battery as the power supply for the radio and another enzyme battery as the sensor, or using an enzyme battery as the power supply for the radio and a different type of sensor as the sensor. use one or more types of enzyme batteries as power sources for radios and sensors, use different types of sensors as sensors, use different types of batteries (coin batteries, etc.) as power sources for radios, and use enzyme batteries as sensors You can
When the above IoT sensor is used as a biosensor for diapers, an enzyme battery can be installed in the diaper and used in the following ways. In the case of a urine sugar level sensor, the sugar in urine is used as a fuel and a sensing target, and the power obtained is used to operate a wireless device. It is possible to operate a wireless device with the power obtained by generating electricity using moisture, or use the sugar in urine as a sensing target and operate the wireless device with the power of another type of battery (coin battery, etc.). In the case of a urination sensor, fuel is built in beforehand and moisture in urine is used as a sensing target. The power obtained can be used to operate a wireless device and a urine sensor of another type, or the moisture in urine can be detected by incorporating fuel in advance, and the wireless device can be operated with the power of another type of battery (coin battery, etc.). can.

When used as a skin-attached sensor and power source, the enzyme battery can be attached directly to the skin or attached to clothing. In the case of a lactic acid sensor in sweat, lactic acid in sweat is used as fuel and a sensing target, and the obtained power is used to operate a wireless device, or lactic acid in sweat is used as a sensing target. Separately, fuel is built in beforehand, and the moisture in sweat is used to generate electricity, and the power obtained is used to operate the wireless device. It can operate wireless devices, and can use the lactic acid in sweat as fuel to operate other types of sensors and wireless devices with the power obtained.

When attaching the enzyme battery directly to the skin, an adhesive for skin attachment and a tape or sheet using the adhesive can be used.

Also, the attachment site is not particularly limited, but a site that perspires a lot is preferable because it can supply a large amount of fuel and water necessary for power generation.

When an enzyme battery is used by attaching it to the skin, it is used as a sensor and a power source for analyzing sweat components, for example. By sensing the concentration of lactic acid and electrolytes in sweat, pH, etc. and acquiring biological information of the target, it is possible to utilize it for diagnosis and monitoring of heatstroke, fatigue, health condition, etc.

In addition to wireless transmission, it is also possible to combine an alarm device and a sensor to transmit sensing information (on-off, etc.) to the outside using light, sound, vibration, or the like.

By using the enzyme battery of the present invention, as described above, it is possible to realize a low-cost, disposable (easy-to-dispose, no-recycling, etc.) device. Examples of easy-to-dispose devices include a conductive layer made of a carbon material coated on paper as a conductive support, a negative electrode in which a mediator and an enzyme are directly supported on the conductive support as a negative electrode for an enzyme battery, and an enzyme battery. Examples of the positive electrode include an enzyme battery prepared by laminating a positive electrode obtained by applying the electrode paste composition for an enzyme battery positive electrode of the present invention to the conductive support, and using paper as a separator. Furthermore, carbon wiring that does not use metal for wiring for connecting the enzyme battery and the device operated by the electric power of the enzyme battery (for example, a conductive layer made of a carbon material used for a conductive support, carbon paper, carbon felt, carbon wiring, etc.) Carbon cloth, etc.), it is possible to realize inexpensive devices that do not require sorting or recycling.

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

EXAMPLES The present invention will be described in more detail with reference to examples below, but the examples below do not limit the scope of the present invention. In the examples and comparative examples, "part" means "mass part" and "%" means "mass %".

The carbon catalyst for the positive electrode of the enzyme battery was measured using the following measuring equipment, and the molar ratio of elements shown in Table 1 (ratio of N1 type nitrogen atomic weight and ratio of N2 type nitrogen atomic weight), surface terminal nitrogen ratio, BET specific surface area, X-ray The diffraction angle peak position and peak half width were obtained. In addition, the existence of carbon atoms forming the hexagonal carbon network plane and nitrogen atoms substituted from the carbon atoms of the hexagonal carbon network plane was confirmed.
- Surface terminal nitrogen: X-ray spectroscopy (XPS) (SHIMADZU/KRATOS AXIS-HS)
・ Measurement of BET specific surface area: Measurement of nitrogen adsorption amount (BELSORP-mini manufactured by Bell Japan)
・X-ray diffraction: Fully automatic horizontal multi-purpose X-ray diffractometer (Smartlab manufactured by Rigaku)
- R _C , R _N , R _M : CHN elemental analysis (2400 model CHN elemental analyzer manufactured by PerkinElmer), ICP emission spectroscopic analysis (SPECTROARCOS FHS12 manufactured by SPECTRO)

<Production of carbon catalyst for positive electrode of enzyme battery>
[Example 1]
Graphene nanoplatelets xGnP-C-750 (manufactured by XGscience) and iron phthalocyanine P-26 (manufactured by Sanyo Color Co., Ltd.) are weighed so that the mass ratio is 1/0.5 (graphene nanoplatelets/iron phthalocyanine). and dry-blended to obtain a mixture. The mixture was filled in an alumina crucible and heat-treated at 800° C. for 2 hours in an electric furnace in a nitrogen atmosphere to obtain a carbon catalyst (1) for an enzyme cell positive electrode.

[Example 2]
Ketjenblack EC-600JD (manufactured by Lion Specialty Chemicals Co., Ltd.) and cobalt phthalocyanine (manufactured by Tokyo Kasei Co., Ltd.) were weighed so that the mass ratio was 1/0.5 (Ketjenblack/cobalt phthalocyanine), and dried. Mixing was performed to obtain a mixture. The mixture was filled in an alumina crucible and heat-treated at 700° C. for 2 hours in an electric furnace in a nitrogen atmosphere to obtain a carbon catalyst (2) for an enzyme cell positive electrode.

[Example 3]
Carbon nanotubes VGCF-H (manufactured by Showa Denko Co., Ltd.) and iron phthalocyanine (manufactured by Sanyo Color Co., Ltd.) are weighed so that the mass ratio is 1/0.5 (carbon nanotubes/iron phthalocyanine), and dry mixing is performed to obtain a mixture. got The mixture was filled in an alumina crucible and heat-treated at 800° C. for 2 hours in an electric furnace in a nitrogen atmosphere to obtain a carbon catalyst (3) for an enzyme cell positive electrode.

[Example 4]
Knobel MJ (4) 150 (manufactured by Toyo Tanso Co., Ltd.) and iron phthalocyanine (manufactured by Sanyo Pigment Co., Ltd.) were weighed so that the mass ratio was 1/0.5 (Knobel / iron phthalocyanine), and dry-mixed to obtain a mixture. got The mixture was filled in an alumina crucible and heat-treated at 800° C. for 2 hours in an electric furnace in a nitrogen atmosphere to obtain a carbon catalyst (4) for an enzyme cell positive electrode.

[Example 5]
A phenolic resin (PSM-4326 manufactured by Gunei Chemical Co., Ltd.) and iron phthalocyanine P-26 (manufactured by Sanyo Color Co., Ltd.) were weighed at a mass ratio of 3.3:1 and wet-mixed in acetone. After distilling off the above mixture under reduced pressure, the residue was pulverized in a mortar to obtain a precursor. The above precursor powder was filled in an alumina crucible and heat-treated in an electric furnace in a nitrogen atmosphere at 600° C. for 2 hours to obtain a carbon sintered body (1). The carbon sintered body (1) was reslurried in concentrated hydrochloric acid and allowed to stand. After the carbon sintered body (1) precipitated, the supernatant liquid was removed. The above operation is repeated until the supernatant is no longer colored, filtered, washed with water, dried, pulverized in a mortar, filled in an alumina crucible, heat-treated in an electric furnace at 800 ° C. for 1 hour in an ammonia atmosphere, and charcoal fired. Result (2) was obtained. The carbon sintered body (2) was reslurried in concentrated hydrochloric acid and allowed to stand. After the carbon sintered body precipitated, the supernatant liquid was removed. After the above operation was repeated until the supernatant was no longer colored, it was filtered, washed with water, dried and pulverized in a mortar to obtain a carbon catalyst (5) for an enzyme battery positive electrode.

[Example 6]
Polyvinylpyridine (PVP, manufactured by Aldrich) was dissolved in dimethylformamide, iron chloride hexahydrate was added in a mass ratio of 2:1 to PVP, and the mixture was stirred at room temperature for 24 hours to obtain a polyvinylpyridine iron complex. The above polyvinylpyridine iron complex is filled in an alumina crucible and heat-treated in an electric furnace under a nitrogen atmosphere at 800° C. for 2 hours. got

[Example 7]
Polyvinylpyridine (PVP, manufactured by Aldrich) was dissolved in dimethylformamide, iron chloride hexahydrate was added in a mass ratio of 2:1 to PVP, and the mixture was stirred at room temperature for 24 hours to obtain a polyvinylpyridine iron complex. The above polyvinylpyridine and Ketjenblack (EC-600JD manufactured by Lion Corporation) were weighed at a mass ratio of 1:1 and dry mixed in a mortar to obtain a precursor. The above precursor powder is filled in an alumina crucible and heat-treated in an electric furnace under a nitrogen atmosphere at 800° C. for 2 hours. Obtained.

[Example 8]
Graphene nanoplatelets xGnP-C-750 (manufactured by XGscience) are filled in an alumina crucible and heat treated at 1000 ° C. for 2 hours in an ammonia nitrogen atmosphere in an electric furnace to produce a carbon catalyst for an enzyme battery positive electrode (8). got

[Example 9]
90 parts of ion-exchanged water, 0.2 parts of iron (II) chloride tetrahydrate, and 3.2 parts of copper phthalocyanine derivative SOLSPERSE 12000 (manufactured by Nippon Lubrizol Co., Ltd.) were weighed into a glass bottle to prepare a uniform aqueous solution. After adding 6.6 parts of Platelet xGnP-C-750 (manufactured by XGscience) and further adding zirconia beads as media, the mixture was dispersed with a paint shaker (manufactured by Mitsuwa Tech Co., Ltd.: Scandex SK450) to form a precursor mixed paste. Obtained. This precursor mixed paste was distilled off under reduced pressure using a rotary evaporator, and the obtained solid content was finely pulverized using a mortar to obtain a uniform precursor powder. The obtained precursor powder was filled in an alumina crucible and heat-treated at 800° C. for 2 hours in an electric furnace under a nitrogen atmosphere to obtain a carbon catalyst (9) for an enzyme cell positive electrode.

<Preparation of electrode paste composition for positive electrode of enzyme battery>
4.8 parts of carbon catalyst (1) for enzyme battery positive electrode, 49.2 parts of water as an aqueous liquid medium, and 40 parts of carboxymethyl cellulose aqueous solution (2% solid content) as a thickening agent were placed in a mixer and mixed, followed by a sand mill. put in and dispersed. Thereafter, 6 parts of an emulsion-type acrylic resin dispersion solution (manufactured by Toyochem Co., Ltd.: W-168) (solid content: 50%) was added as a binder and mixed with a mixer to obtain an enzyme battery positive electrode paste composition (1).

Using the carbon catalysts (2) to (9) for the positive electrode of the enzyme battery, the electrode paste compositions (2) to (9) for the positive electrode of the enzyme battery are prepared in the same manner as the electrode paste composition (1) for the positive electrode of the enzyme battery. Obtained.

[Comparative Example 1]
4.8 parts of a supported platinum catalyst TEC10E30E (manufactured by Tanaka Kikinzoku Co., Ltd.), 49.2 parts of water as an aqueous liquid medium, and 40 parts of an aqueous carboxymethylcellulose solution (2% solid content) as a thickening agent were added to a mixer and mixed. It was placed in a sand mill and dispersed. Thereafter, 6 parts of an emulsion-type acrylic resin dispersion solution (manufactured by Toyochem Co., Ltd.: W-168) (solid content: 50%) was added as a binder and mixed with a mixer to obtain an enzyme battery positive electrode paste composition (10).

[Comparative Example 2]
4.8 parts of activated carbon (manufactured by CABOT), 49.2 parts of water as an aqueous liquid medium, and 40 parts of an aqueous carboxymethyl cellulose solution (2% solid content) as a thickening agent were added to a mixer and mixed, and then added to a sand mill. Dispersed. After that, 6 parts of an emulsion-type acrylic resin dispersion solution (manufactured by Toyochem Co., Ltd.: W-168) (solid content: 50%) was added as a binder and mixed with a mixer to obtain an enzyme battery positive electrode paste composition (11).

<Preparation of positive electrode for enzyme battery>
The electrode paste compositions (1) to (9) for the positive electrode of the enzyme battery of Examples 1 to 9 and the electrode paste compositions (10) to (11) for the positive electrode of the enzyme battery of Comparative Examples 1 and 2 were treated with a doctor blade. It was coated on a carbon paper base material made by Toray Industries, Inc. as a conductive support so that the basis weight of the carbon catalyst for the positive electrode of the enzyme battery after drying was 2 mg/cm ² , and then dried in an air atmosphere at 95°C and 60°C. After drying for 1 minute, positive electrodes (1) to (11) for enzyme batteries were produced.

[Comparative Example 3]
Conductive carbon material (1) (furnace black, VULCAN (registered trademark) XC72, manufactured by CABOT) paste was dried on a carbon paper substrate manufactured by Toray Industries, Inc. with a doctor blade. cm ² , an aqueous solution of oxygen reducing enzyme bilirubin oxidase was added dropwise, followed by air drying to prepare a positive electrode (12) for an enzyme battery.

<Production of negative electrode for enzyme battery>
Conductive carbon material (1) (furnace black, VULCAN (registered trademark) XC72, manufactured by CABOT) paste was dried on a carbon paper substrate manufactured by Toray Industries, Inc. with a doctor blade. cm ² , then a methanol solution of tetrathiafulvalene and an aqueous solution of glucose oxidase were added dropwise, followed by air drying to prepare a negative electrode (1) for an enzyme battery.

Further, an enzyme battery negative electrode (2) was produced in the same manner as the enzyme battery negative electrode (1), except that the glucose oxidase aqueous solution was changed to the lactate oxidase aqueous solution.

<Output stability evaluation>
Output stability evaluation of the positive electrode for an enzyme battery was performed as follows.
Using the positive electrode for enzyme battery (1) to (12) prepared above as the working electrode and the negative electrode for enzyme battery (1) as the counter electrode, 0.1 M phosphate buffer (pH 7.0) as an electrolytic solution (ionic conductor) ), and after performing oxygen bubbling for 30 minutes, add D-glucose as fuel to 0.01 M, add a small amount of albumin (protein) as an impurity, and potentiogalvanostat (VersaSTAT3, Princeton Applied Research), Linear Sweep Voltammetry (LSV) was performed at pH 7 at room temperature and evaluated.
The standard deviation of three measurements of the maximum output (mW/cm ² ) obtained from the reduction current curve obtained from the LSV measurement was used as an index of output stability and evaluated.
Table 1 shows the results obtained.

<Durability evaluation>
Durability evaluation of the positive electrode for an enzyme battery was performed as follows.
Using the positive electrodes (1) to (12) for the enzyme battery prepared above as the working electrode, the platinum coiled electrode as the counter electrode, and the silver-silver chloride electrode (Ag/AgCl) as the reference electrode, the electrolytic solution (ionic conductor) After placing in a certain 0.1 M phosphate buffer (pH 7.0) and performing oxygen bubbling for 30 minutes, D-glucose was added as a fuel to 0.01 M, and albumin (protein) was added as an impurity. was added, and 50 cycles of cyclic voltammetry (CV) were performed at pH 7 and room temperature using a potentio-galvanostat (VersaSTAT3, manufactured by Princeton Applied Research).
LSV measurement was performed before and after the CV measurement, the potential at which the current density reached −50 μA/cm ² was defined as the oxygen reduction starting potential, and the retention rate obtained from the oxygen reduction starting potential before and after the CV, which was obtained by the following formula, was used for the enzyme battery. It was evaluated as an index of the durability of the positive electrode. The oxygen reduction initiation potential indicates that the higher the potential, the higher the oxygen reduction activity.
Retention rate = (oxygen reduction initiation potential after CV measurement))/(oxygen reduction initiation potential before CV measurement) x 100 (%)
Table 1 shows the results obtained.

Evaluation criteria for output stability and durability are shown below.

(Output stability evaluation)
◎: Maximum output standard deviation (measured three times) less than 4 μW/cm ² (good)
○: Maximum output standard deviation (three measurements) less than 8 μW/cm ² 4 μW/cm ² or more △: Maximum output standard deviation (three measurements) less than 10 μW/cm ² 8 μW/cm ² or more (practically no problem)
×: Maximum output standard deviation (measured three times) 10 μW/cm ² or more (defective)
-: Power generation not confirmed

(Durability evaluation)
◎: Oxygen reduction initiation potential retention rate 90% or more (good)
O: Oxygen reduction initiation potential retention rate 50% or more and less than 90% (no practical problem)
△: Oxygen reduction start potential retention rate 10% or more and less than 50% (defective)
×: Oxygen reduction initiation potential retention rate less than 10% (extremely poor)

In comparison with the comparative example, the example showed high output stability and durability of the battery performance. This is because, in the comparative example, organic substances contained as fuel and impurities poisoned the surface of the catalyst, inhibiting the positive electrode reaction, and the low stability of the catalyst with respect to potential contributed to the deterioration of output stability and durability. Presumably because they are connected. As described above, even in the operating environment of an enzyme battery, which requires potential resistance because the measured values are likely to vary due to impurities, etc., it has been clarified that the Examples exhibit high output stability and durability of the battery performance.

<Evaluation of sensing ability for glucose>
Using the enzyme battery positive electrode (1) as a working electrode and the enzyme battery negative electrode (1) as a counter electrode, they are placed in a 0.1 M phosphate buffer solution (pH 7.0), which is an electrolytic solution (ionic conductor), and left for 30 minutes. After oxygen bubbling, a potentio-galvanostat (VersaSTAT3, manufactured by Princeton Applied Research) was used to measure LSV at pH 7 and room temperature, with a glucose concentration of 0.001 to 0.01M as a fuel (sensing object). We investigated the responsiveness of the oxidation current to The results are shown in FIG.
As is clear from FIG. 1, it was found that the glucose oxidation activity changed proportionally according to the change in the glucose concentration. It has been found that it can be used as a glucose sensor as well as a self-powered sensor.

<Production of enzyme battery>
The enzyme battery positive electrode (1) was used as the working electrode, the enzyme battery negative electrode (1) was used as the counter electrode, glucose (0.34 mg/cm ² ) was used as a fuel on the separator, and sodium chloride was supported as an ionic conductor on filter paper (No. 5C ADVANTEC) was used to fabricate an enzyme battery (1) by laminating the positive electrode, the separator, and the negative electrode in this order. Enzyme batteries (2) and (3) were produced in the same manner as in enzyme battery (1), except that the amounts of glucose supported on the separators were 4 and 7.8 mg/cm ² . Furthermore, an enzyme battery (4) was produced in the same manner as the enzyme battery (1), except that glucose was not supported on the separator.

<Evaluation of sensing performance for moisture>
Sensing ability evaluation for moisture was performed as follows.
Ultrapure water was added dropwise to the separator portions of the enzyme batteries (1) to (4) prepared above, and LSV was measured at room temperature using a potentio-galvanostat (VersaSTAT3, manufactured by Princeton Applied Research). rice field. The maximum output was calculated from the reduction current curve obtained from the LSV measurement. For the enzyme cell (4), instead of ultrapure water, a glucose solution containing an excess amount of D-glucose (0.1 M) was dropped as a fuel using a dropper, and LSV was measured in the same manner. Using the ratio of the maximum output of the sensor as an index, the sensing ability for moisture was evaluated. The results obtained are shown in FIG.
From FIG. 2, it was found that the presence or absence of power generation changes depending on the water content by preliminarily incorporating glucose as a fuel into the enzyme battery. It became clear that it can be used as a moisture sensor. In addition, changes in the output were also observed depending on the amount of glucose supported. When the amount of glucose supported was 4 mg/cm ² or more, a value equivalent to the maximum output under the condition of using a 0.1 M glucose solution, which was used as an index, was exhibited. This is because, under these conditions, if the amount of glucose supported is 4 mg/cm ² or more, the dissolved glucose causes the glucose concentration in the ultrapure water to become 0.1 M or more (excess), and the equivalent maximum output was exhibited. Conceivable.
In this study, we showed an example of the evaluation of the sensing ability for moisture, but since the upper limit of the glucose concentration that is excessive for the enzyme reaction differs depending on the system used, It is appropriately selected depending on the system to be used.

<Production of enzyme battery using paper substrate>
Conductive carbon material (2) (spherical graphite CGB-50, manufactured by Nippon Graphite Co., Ltd.) 25.2 parts and conductive carbon material (3) (Ketjenblack EC-300J, manufactured by Lion Corporation) 6.3 parts, aqueous liquid 40.8 parts of water as a medium and 22.5 parts of an aqueous carboxymethyl cellulose solution (2% solid content) as a thickening agent were added to a mixer, mixed, and dispersed in a sand mill. After that, 5.2 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 a conductive paste composition for a conductive carbon layer.

After applying the conductive paste composition obtained above on a filter paper substrate (No. 5C ADVANTEC) with a doctor blade so that the basis weight of the conductive carbon material after drying is 1 mg/cm ² , It was dried in the atmosphere at 95° C. for 60 minutes to obtain a conductive carbon layer using filter paper as a base material.
A methanol solution of tetrathiafulvalene and an aqueous solution of glucose oxidase as mediators were dropped onto the conductive carbon layer, respectively, and air-dried to prepare a negative electrode for an enzyme battery using filter paper as a base material. The electrode paste composition (1) for the positive electrode of an enzyme battery is applied to the conductive carbon layer with a doctor blade so that the basis weight of the carbon catalyst for the positive electrode of an enzyme battery after drying is 2 mg/cm ² on a filter paper substrate. After that, it was dried in the atmosphere at 95° C. for 60 minutes to prepare a positive electrode for an enzyme battery using filter paper as a base material.

A filter paper supporting glucose as a fuel and sodium chloride as an ionic conductor is used as a separator, and a positive electrode for an enzyme battery using the filter paper as a base material, a separator, and a negative electrode for an enzyme battery using the filter paper as a base material are laminated in this order. An enzyme battery (5) was produced.

<Construction of wireless communication circuit>
The prepared enzyme cell (5), a boost converter (LTC3108, manufactured by Strawberry Linux), and a wireless device (transmission module IM315TX, receiver module IM315RX, manufactured by Interplan) are combined to form a wireless communication circuit as shown in the block diagram of FIG. It was constructed.

<Wireless sensor system using enzyme battery>
After constructing the above circuit, when ultrapure water was dropped onto the separator portion of the enzyme battery (5) using a dropper, signal reception was confirmed in the receiver module. This indicates that the enzymatic battery generated electricity by dropping water, and the power at that time activated the transmission module and sent a signal. That is, it was found that an enzyme battery using the positive electrode for an enzyme battery produced according to the present invention can be used as a wireless moisture sensor system that does not require a power source.
Furthermore, the enzyme battery (5) does not use expensive precious metals or oxygen reductase, and uses paper as the base material, so it is a low-cost and disposable (easily discarded, no recycling required, etc.) device. ing. Therefore, it was shown that the enzyme battery (5) can be used as a disposable wireless urination sensor by incorporating it into a paper diaper, for example, as a urination sensor.

<Sensing ability evaluation for lactic acid>
Using the enzyme battery positive electrode (1) as a working electrode and the enzyme battery negative electrode (2) as a counter electrode and a reference electrode, put them in a 0.1 M phosphate buffer solution (pH 7.0) as an electrolytic solution (ionic conductor), Using a potentio-galvanostat (VersaSTAT3, manufactured by Princeton Applied Research), pH 7, LSV measurement at room temperature, power density at 0.1 V for lactic acid concentration 0.01 to 0.1 M, which is the fuel (sensing object) examined. The results are shown in FIG.
As is clear from FIG. 4, it was found that the lactate oxidation activity changed proportionally according to the change in lactic acid concentration. It has been found that it can be used as a lactic acid sensor as well as a self-powered sensor.
Furthermore, by combining with a wireless sensor system or the like that does not require a power source, it can be used as a skin-attached sensor and/or power source, and as a wireless biological information sensor. For example, it was suggested that it could be used as a sensor that senses the concentration of lactic acid in sweat, or that the lactic acid in sweat could be used as fuel to generate electricity to drive a sensor or transmission module.

Claims (18)

A self-power generating sensor formed using a positive electrode for an enzyme battery having a coating film formed from an electrode paste composition for a positive electrode for an enzyme battery containing a carbon catalyst for an enzyme battery positive electrode, at least a solvent, and a binder. There is
The carbon catalyst for an enzyme battery positive electrode is a carbon catalyst for an enzyme battery positive electrode made of a carbon material having a carbon hexagonal network plane as a basic skeleton, and contains a hetero element that is a nitrogen element as a constituent element, and the hetero element is in the carbon skeleton. is doped to replace at least a portion of the carbon elements of and has oxygen reduction activity, and
The carbon catalyst for the enzyme battery positive electrode is measured by X-ray photoelectron spectroscopy (XPS), where N is the molar ratio of nitrogen atoms to all elements on the catalyst surface, and the peak of the N1s spectrum of XPS with respect to the total nitrogen amount on the catalyst surface The surface terminal nitrogen ratio {N × (N ₁ + N ₂ ) } is 0 , where the sum (%) of the ratio of the N1-type nitrogen atomic weight and the ratio of the N2-type nitrogen atomic weight obtained by separation is (N ₁ + N ₂ ). .2 to 25.0%, and when the molar ratio of carbon atoms and the molar ratio of nitrogen atoms to all elements constituting the carbon catalyst are R C and R N, respectively, _the ratio _of R N _to R _C The proportion is 0.5-40%
Self-powered sensor . The carbon catalyst for an enzyme battery positive electrode further contains a base metal element as a constituent element, and the base metal element contains one or more selected from the group consisting of cobalt, iron and copper, and
When the molar ratio of carbon atoms, the molar ratio of nitrogen atoms, and the molar ratio of base metal atoms to all elements constituting the carbon catalyst are R _C , R _N , and R _M , respectively, the ratio of R _N to R _C is 1 ~
40%, and the ratio _{of RM to RC is} 0.01-20%.
The carbon catalyst for an enzyme battery positive electrode has a BET specific surface area (BET _N2 ) with nitrogen as an adsorbing species of 50 to 1200 m ² /g.
The self-powered sensor according to claim 1 or 2 . The carbon catalyst for an enzyme battery positive electrode has a peak at a diffraction angle (2θ) of 24.0 to 27.0° in an X-ray diffraction diagram obtained using CuKα rays as an X-ray source, and half of the peak The price range is 8 degrees or less
The self-powered sensor according to any one of claims 1 to 3 . The electrode paste composition for an enzyme battery positive electrode further contains a dispersant
The self-powered sensor according to any one of claims 1-4 . An organic substance sensor formed using an enzyme battery positive electrode having a coating film formed from an enzyme battery positive electrode paste composition containing a carbon catalyst for an enzyme battery positive electrode, at least a solvent, and a binder, ,
The carbon catalyst for an enzyme battery positive electrode is a carbon catalyst for an enzyme battery positive electrode made of a carbon material having a carbon hexagonal network plane as a basic skeleton, and contains a hetero element that is a nitrogen element as a constituent element, and the hetero element is in the carbon skeleton. is doped to replace at least a portion of the carbon elements of and has oxygen reduction activity, and
The carbon catalyst for the enzyme battery positive electrode is measured by X-ray photoelectron spectroscopy (XPS), where N is the molar ratio of nitrogen atoms to all elements on the catalyst surface, and the peak of the N1s spectrum of XPS with respect to the total nitrogen amount on the catalyst surface The surface terminal nitrogen ratio {N × (N ₁ + N ₂ ) } is 0 , where the sum (%) of the ratio of the N1-type nitrogen atomic weight and the ratio of the N2-type nitrogen atomic weight obtained by separation is (N ₁ + N ₂ ). .2 to 25.0%, and when the molar ratio of carbon atoms and the molar ratio of nitrogen atoms to all elements constituting the carbon catalyst are R C and R N, respectively, _the ratio _of R N _to R _C The proportion is 0.5-40%
Organic matter sensor . The carbon catalyst for an enzyme battery positive electrode further contains a base metal element as a constituent element, and the base metal element contains one or more selected from the group consisting of cobalt, iron and copper, and
When the molar ratio of carbon atoms, the molar ratio of nitrogen atoms, and the molar ratio of base metal atoms to all elements constituting the carbon catalyst are R _C , R _N , and R _M , respectively, the ratio of R _N to R _C is 1 ~
7. The organic matter sensor according to claim 6, wherein the ratio of R _M to R _C is 40% and R C is 0.01 to 20%.
The carbon catalyst for an enzyme battery positive electrode has a BET specific surface area (BET _N2 ) with nitrogen as an adsorbing species of 50 to 1200 m ² /g.
The organic substance sensor according to claim 6 or 7 . The carbon catalyst for an enzyme battery positive electrode has a peak at a diffraction angle (2θ) of 24.0 to 27.0° in an X-ray diffraction diagram obtained using CuKα rays as an X-ray source, and half of the peak The price range is 8 degrees or less
The organic substance sensor according to any one of claims 6 to 8 . The electrode paste composition for an enzyme battery positive electrode further contains a dispersant
The organic substance sensor according to any one of claims 6 to 9 . An enzyme battery formed by using a positive electrode for an enzyme battery having a coating film formed from an electrode paste composition for an enzyme battery positive electrode containing a carbon catalyst for an enzyme battery positive electrode, at least a solvent, and a binder is used. A moisture sensor formed by
The carbon catalyst for an enzyme battery positive electrode is a carbon catalyst for an enzyme battery positive electrode made of a carbon material having a carbon hexagonal network plane as a basic skeleton, and contains a hetero element that is a nitrogen element as a constituent element, and the hetero element is in the carbon skeleton. is doped to replace at least a portion of the carbon elements of and has oxygen reduction activity, and
The carbon catalyst for the enzyme battery positive electrode is measured by X-ray photoelectron spectroscopy (XPS), where N is the molar ratio of nitrogen atoms to all elements on the catalyst surface, and the peak of the N1s spectrum of XPS with respect to the total nitrogen amount on the catalyst surface The surface terminal nitrogen ratio {N × (N ₁ + N ₂ ) } is 0 , where the sum (%) of the ratio of the N1-type nitrogen atomic weight and the ratio of the N2-type nitrogen atomic weight obtained by separation is (N ₁ + N ₂ ). .2 to 25.0%, and when the molar ratio of carbon atoms and the molar ratio of nitrogen atoms to all elements constituting the carbon catalyst are R C and R N, respectively, _the ratio _of R N _to R _C The proportion is 0.5-40%
moisture sensor . The carbon catalyst for an enzyme battery positive electrode further contains a base metal element as a constituent element, and the base metal element contains one or more selected from the group consisting of cobalt, iron and copper, and
When the molar ratio of carbon atoms, the molar ratio of nitrogen atoms, and the molar ratio of base metal atoms to all elements constituting the carbon catalyst are R _C , R _N , and R _M , respectively, the ratio of R _N to R _C is 1 ~
12. The moisture sensor according to claim 11, wherein the ratio of R _M to R _C is 0.01 to 20%. The carbon catalyst for an enzyme battery positive electrode has a BET specific surface area (BET _N2 ) with nitrogen as an adsorbing species of 50 to 1200 m ² /g.
The moisture sensor according to claim 11 or 12 . The carbon catalyst for an enzyme battery positive electrode has a peak at a diffraction angle (2θ) of 24.0 to 27.0° in an X-ray diffraction diagram obtained using CuKα rays as an X-ray source, and half of the peak The price range is 8 degrees or less
The moisture sensor according to any one of claims 11-13 . The electrode paste composition for an enzyme battery positive electrode further contains a dispersant
The moisture sensor according to any one of claims 11-14 . 16. The moisture sensor according to any one of claims 11 to 15, wherein the fuel is at least one selected from the group consisting of glucose, lactic acid and fructose. The self-power generation sensor according to any one of claims 1 to 5, wherein the fuel and/or sensing object is at least one selected from the group consisting of glucose, lactic acid, and fructose. 11. The organic substance sensor according to any one of claims 6 to 10, wherein the object to be sensed is at least one selected from the group consisting of glucose, lactic acid and fructose.

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