JP7634830B2 - Gas sensing material and its manufacturing method - Google Patents

Description

The present invention relates to a gas sensing material and a method for producing the same.
Related Art
This application claims domestic priority under Article 41 of the Japanese Patent Law based on Japanese Patent Application No. 2020-030315 (filing date: February 26, 2020 (Reiwa 2)), and the present invention is based on the contents disclosed in that patent application. For reference, the contents described in the specification and drawings of that patent application are incorporated by reference into the specification of this application.

Gas sensing materials are used in a variety of fields, including production environments, residential environments, medical and health environments, pollution, and drugs. In particular, interest in gas sensing materials is growing for the detection and monitoring of gases harmful to animals and plants, the detection and sensing of VOCGs (Volatile Organic Compounds Gas) in residential and living environments (indoor environments), medical and health environments, and storage environments for home appliances (refrigerators, air purifiers, etc.), as well as health monitoring technology.

In recent years, gas sensing materials adapted to various fields and environments have been proposed. For example, 1) semiconducting metal oxides, such as SnO ₂ and TiO ₂ , are the most widely used sensing materials, and are used in the high temperature range (300° C. or higher). 2) Conductive polymers, such as polypyrrole (PPy), polyaniline (PANI), polythiophene (PTH), etc., can be used near room temperature (about 25° C.), and have ease of design and processing of sensing materials. For example, Non-Patent Document 1 "Fabrication of polypyrrole-phenylalanine nano-films with NH ₃ gas sensitivity" discloses a polypyrrole (PPy) film complexed with phenylalanine that exhibits ammonia sensitivity, and a method for synthesizing the same. 3) Organic semiconductors (e.g., phthalocyanine) are also known as semiconductor materials.

In recent years, the field of gas sensing has required high sensitivity, high selectivity, and the ability to be used at low to normal temperatures, in the presence of moisture, and under humid conditions. There is also a demand for gas sensing materials and methods for producing the same that are flexible, thin, compact, easy to use, and inexpensive.

Therefore, there is still a demand for the development of gas sensing materials with excellent and diverse functionality, as well as simple and inexpensive methods for manufacturing gas sensing materials.

“Fabrication of polypyrrole-phenylalanine nano-films with NH3 gas sensitivity” (Jin-Yeol Kim et.al, Sensors and Actuators B: Chemical; Volume 153, Issue 2, 20 April 2011, Pages 421-426)

The present invention proposes a gas sensing material with high sensitivity, high selectivity, and a wide range of usability, and a method for producing the same.

[One aspect of the present invention]
The present invention proposes the following as one aspect thereof.
[1] A gas sensing material comprising:
A gas sensing material comprising a polypyrrole derivative represented by the following chemical formula I and a carbon material.

[In the above chemical formula I,
A is an alkyl group having 1 to 10 carbon atoms or a phenyl group,
B is a hydrogen atom, a halogen atom or a halogen compound;
S is a sulfur atom, a nitrogen atom, an oxygen atom, or a polar compound composed of these atoms;
A, B, and S are different substances;
n is 100 or more and 100,000 or less.
[2] A gas sensing material comprising:
The coating composition comprises at least a first layer and a second layer,
Either the first layer or the second layer comprises a polypyrrole derivative represented by the following chemical formula I:
The gas sensing material, wherein the other of said first layer or said second layer comprises a carbon material.

[In the above chemical formula I,
A is an alkyl group having 1 to 10 carbon atoms or a phenyl group,
B is a hydrogen atom, a halogen atom or a halogen compound;
S is a sulfur atom, a nitrogen atom, an oxygen atom, or a polar compound composed of these atoms;
A, B, and S are different substances;
n is 100 or more and 100,000 or less.
[3] The gas sensing material according to [1] or [2], wherein the carbon material is one or a combination of two or more selected from the group consisting of natural or synthetic (cubic crystal system) diamond, lonsdaleite, graphite, amorphous carbon, glassy carbon, graphene, fullerene, carbon nanotube, carbon nanohorn, carbon nanobud, carbon nanofiber, carbon nanofoam, and carbyne.
[4] The gas sensing material according to any one of [1] to [3], wherein the compound represented by [Chemical Formula I] and the carbon material are bonded directly or via a bonding group.
[5] The bonding group is a divalent bonding group, and is, for example, -(C ₂ )m (m is 1 or more and 10 or less)-, -O-, -S-, -OCH ₂ -, -CH ₂ O-, -CO-, -COO-, -OCO-, -CO-S-, -S-CO-, -O-CO-O-, -CO-NH-, -NH-CO-, -SCH ₂ -, -CH ₂ S-, -CF ₂ O-, -OCF ₂ -, -CF _{2 S-, -SCF 2 -} , -CH=CH-COO-, -CH=CH-OCO-, -COO-CH=CH-, -OCO-CH=CH-, -COO-CH ₂ CH ₂ -, -OCO-CH ₂ CH ₂ -, -CH ₂ CH ₂ -COO-, -CH ₂ CH ₂ The gas sensing material according to [5], which is one or a combination of two or more selected from the group consisting of -OCO-, -COO- _CH2- , -OCO- _CH2- , -CH2 _- COO-, -CH2-OCO-, -CH=CH-, -N=N-, -CH=N-N=CH-, -CF=CF-, and -C≡C-.
[6] A gas sensing material comprising:
A gas sensing material having a structure of a polypyrrole derivative and carbon nanotubes, represented by the following chemical formula II.

[In the above chemical formula II,
A is an alkyl group having 1 to 10 carbon atoms or a phenyl group,
B is a hydrogen atom, a halogen atom or a halogen compound;
S is a sulfur atom, a nitrogen atom, an oxygen atom, or a polar compound composed of these atoms;
A, B, and S are different substances;
n is 100 or more and 100,000 or less.
[7] The gas sensing material according to any one of [1] to [6], wherein the gas is a nitrogen-based compound, an alcohol, a ketone, or an aldehyde.
[8] The gas-sensing material according to any one of [1] to [6], wherein the gas is a thiol compound.
[9] A gas sensing material comprising:
The gas is ammonia,
In the above [Chemical Formula I] and the above [Chemical Formula II],
A is a phenyl group;
B is a hydrogen atom, a halogen atom or a halogen compound;
S is a nitrogen atom or a nitrogen-containing functional group;
A, B, and S are different substances;
The gas sensing material according to any one of [1] to [6], wherein n is 100 or more and 100,000 or less.
[10] A gas sensing material comprising:
The gas is acetone,
In the above [Chemical Formula I] and [Chemical Formula II],
A is a methyl group or an oxygen atom;
B is a hydrogen atom or a sulfur atom;
S is ^-OH , -OH or -COOH;
A, B, and S are different substances;
The gas sensing material according to any one of [1] to [6], wherein n is 100 to 100,000.
[11] The gas sensing material according to any one of [1] to [10], which senses at 1 atmospheric pressure and a relative humidity of 10% or more and 100% or less.
[12] A gas sensing material comprising:
The present invention has a structure of a polypyrrole derivative and carbon nanotubes represented by the following [chemical formula III],
The gas sensing material, wherein the gas is acetone, ammonia, formaldehyde, or methyl mercaptan.
[Chemical Formula III]
[13] A gas sensing material comprising:
The present invention has a structure of a polypyrrole derivative and carbon nanotubes represented by the following chemical formula IV:
The gas sensing material, wherein the gas is acetone.

[14] The gas sensing material according to any one of [1] to [13], which senses at 1 atmospheric pressure and at a temperature of -50°C or higher and 100°C or lower.
[15] A gas sensor comprising:
The device comprises a positive electrode, a negative electrode, and a gas sensing material,
A gas sensor, wherein the gas sensing material is as described in any one of [1] to [14].
[16] A method for producing a gas sensing material, comprising the steps of:
(S1) preparing a conjugated polymer monomer, a carbon material, a transition metal salt catalyst, an emulsifier and/or a dispersant, and a functional organic substance;
(S2) A carbon material, a transition metal salt, and an emulsifier and/or a dispersant are mixed to obtain a dispersion,
(S3) adding the conjugated polymer monomer and the functional organic substance to the dispersion liquid and carrying out emulsion polymerization;
(S4) purifying and separating the polymerization product to obtain the gas sensing material.
[17] The gas sensing material according to any one of [1] to [14],
The gas sensing material is
(S1) preparing a conjugated polymer monomer, a carbon material, a transition metal salt catalyst, an emulsifier and/or a dispersant, and a functional organic substance;
(S2) A carbon material, a transition metal salt, and an emulsifier and/or a dispersant are mixed to obtain a dispersion,
(S3) adding the conjugated polymer monomer and the functional organic substance to the dispersion liquid and carrying out emulsion polymerization;
(S4) A gas sensing material obtained by purifying and separating the polymerization product.

The gas sensing material of the present invention can achieve high sensitivity, high selectivity, a wide range of use possibilities, compact size, and low power consumption.

In particular, the gas sensing material according to the present invention is configured as nano-sized particles or rods, and senses specific gases with high selectivity. In addition, since the functional groups A, B, and S (also called gas sensing functional groups) in the following chemical formula I are bonded to the carbon material, it is possible to improve the sensitivity to specific gases.

In addition, the gas sensing material of the present invention can be easily formed into a thin film, and as a gas sensing thin film material, it has sufficient conductivity and is sensitive enough to detect minute amounts of gas components even with a minute current resistance of about a few μA.

Furthermore, the presence of the gas sensing functional group provides high selectivity for specific gas components, and has the function of being able to sense even extremely small amounts of gas components of 1 ppm or less. The gas sensing material of the present invention can exhibit gas sensing properties in low to high temperature ranges, for example, from -50°C to 150°C, particularly at temperatures in general use (from 0°C to 40°C, particularly around room temperature of about 25°C). The gas sensing material of the present invention can exhibit the effect of maintaining stable sensing performance even under high humidity conditions (relative humidity of 10% to 100%). In addition, since these nanosensing structures exist in a state of dispersion in an aqueous solution or an organic solvent such as alcohol, they can be easily cast onto a substrate, and are convenient in the processing step in that a thin film can be easily produced.

The manufacturing method of the present invention makes it possible to obtain a gas sensing material that is simple, compact, and inexpensive. In particular, the manufacturing method of the present invention makes it possible to easily introduce functional groups (gas sensing functional groups) A, B, and S into a conjugated polymer, and by combining it with a carbon material (which mainly exhibits electrical conductivity), an electron transfer channel can be established, and sufficient contact reaction (sensing) can be achieved for gas components that come into contact with it from the outside. In particular, it is possible to achieve sensitivity to a specific gas component by changing the current density upon contact with a specific gas component (nitrogen-based substance, for example, ammonia).

FIG. 1 is a conceptual diagram showing a gas sensor equipped with a gas sensing material. FIG. 2 is a schematic diagram showing the surface structure of the gas sensing material. FIG. 3 is a schematic diagram showing a gas-sensing material in which polypyrrole having a specific gas-sensing functional group bound to its surface is combined with carbon nanotubes by capping. FIG. 4 is a magnified SEM image of nanoparticles of the gas sensing material according to the present invention. FIG. 5 is a magnified SEM image of the nanotubes of the gas sensing material according to the present invention. FIG. 6 shows the resistance change indicating the gas response of the gas sensor according to the present invention. FIG. 7 shows the resistance change indicating the gas response of a gas sensing sensor that does not use a carbon material. FIG. 8 is a graph showing the evaluation of the sensing performance for ammonia gas. FIG. 9 is a graph showing the evaluation of the response performance of ammonia gas under humidification. FIG. 10 is a graph evaluating the response performance of ammonia gas under humidification. FIG. 11 is a graph evaluating the response performance of ammonia gas measured at relative humidity of 50% and 70%. FIG. 12 is a graph evaluating the response performance of ammonia gas under humidified conditions in the examples and comparative examples. FIG. 13 illustrates the resistance change representing the response of the gas sensor of the present invention to acetone gas. FIG. 14 illustrates the resistance change representing the response of the gas sensor of the present invention to acetone gas. FIG. 15 illustrates the resistance change representing the response of the gas sensor of the present invention to ammonia gas. FIG. 16 illustrates the resistance change representing the response of the gas sensor of the present invention to ammonia gas. FIG. 17 illustrates the resistance change representative of the formaldehyde gas response of the gas sensor according to the present invention. FIG. 18 illustrates the resistance change representative of the formaldehyde gas response of the gas sensor according to the present invention. FIG. 19 illustrates the resistance change representative of the response of a gas sensor according to the present invention to methyl mercaptan gas.

[Gas sensing material]
The gas sensing material is a concept that encompasses all categories of materials that sense, detect, detect, confirm, etc. gas, without being bound by the word "sensing" in the name, such as gas sensing materials, gas detection materials, gas detection materials, gas confirmation materials, etc.

One aspect of the present invention is a gas sensing material comprising polypyrrole represented by the following chemical formula I and a carbon material.
The gas sensing material of the present invention has high sensitivity, high selectivity, a wide range of usable mobility, thin film thickness, and flexibility, and when used in a sensing device, it is possible to achieve miniaturization and low power consumption.

In one aspect of the present invention, there is provided a gas sensing material comprising:
The coating composition comprises at least a first layer and a second layer,
Either the first layer or the second layer comprises a compound represented by the following chemical formula I:
It can be proposed that either the first layer or the second layer, the other of which comprises a carbon material.

Compound represented by [Chemical Formula I] In the present invention, a polypyrrole derivative represented by the following [Chemical Formula I], that is, a polypyrrole derivative having functional groups (gas sensing functional groups) A, B, and S, is used. This compound imparts high sensitivity, high selectivity, and a wide range of usability as a gas sensing material.

In the above formula I,
A is an alkyl group having 1 to 10 carbon atoms or a phenyl group,
B is a hydrogen atom, a halogen atom or a halogen compound;
S is a sulfur atom, a nitrogen atom, an oxygen atom, or a polar compound composed of these atoms;
A, B, and S are different substances;
n is equal to or greater than 100 and equal to or less than 100,000.

In the above A, examples of the alkyl group having 1 to 10 carbon atoms include CH ₃ --, CH ₃ CH ₂ --, and combinations thereof, and examples of the phenyl group include C ₆ H ₅ --, C ₆ H ₅ CH ₂ --, and combinations thereof.

In the above B, the halogen atom may be one or a combination of two or more selected from the group consisting of fluorine atom (F), chlorine atom (Cl), bromine atom (Br), iodine atom (I), and astatine atom (At), which belong to group 17 of the periodic table, and preferably one or a combination of two or more selected from the group consisting of fluorine atom (F), chlorine atom (Cl), and bromine atom (Br).

In the above B, the halogen compound may be, for example, one or a combination of two or more selected from the group consisting of H-, Cl-, and F-. Preferably, in order to differentiate the function from that of A, it is composed of different compounds having optical isomer structures, and imparts an alignment or directionality to the molecular structure.

In the S, examples of polar compounds composed of sulfur, nitrogen, or oxygen atoms include one or more combinations selected from the group consisting of -O-, -OCH ₂ -, -CO-, -COO-, CO-NH-, -CH=CH-COO-, -OCO-CH ₂ -, -C=O, -NH ₃ , -OH ²⁺ , -OH, and -COOH. The selectivity of gas components is distinguished based on the molecular structure of the S composed of these groups. For example, -NH ₃ is selectively sensitive to ammonia gas components, and -C=O, -CH=CH-COO-, or -COOH can have high sensitivity to gas components such as acetone or aldehyde (preferably formaldehyde). Of course, these descriptions are illustrative, and the present invention is not limited to the selectivity or functionality of the S for a specific gas.

In particular, the structure of the functional groups S and A in the surface structure of the nano-substance determines the selectivity of the gas to be detected, as shown in Figure 3. The basic structure of the functional groups S and A can include a carboxyl group, an alcohol group, a ketone group, an amine group, a phenyl, and a C1 _{-C6 compound} . It is preferable that the functional groups S and A are composed of different substances having structural characteristics as optical isomers.

n is 100 or more and 100,000 or less, and preferably 1,000 or more and 10,000 or less.

(Carbon materials)
Carbon materials are made up of carbon atoms, and mainly allotropes of carbon are used. Carbon materials, as gas sensing materials, impart high electrical conductivity and realize high sensing properties.

Examples of the carbon material include one or a combination of two or more selected from the group consisting of natural or synthetic (cubic crystal system) diamond , lonsdaleite (natural or synthetic hexagonal crystal diamond), graphite (plate-like graphene laminate; for example, graphite, graphite), amorphous carbon (carbon powder such as charcoal, activated carbon, carbon black, or acetylene black), glassy carbon, graphene, fullerene (spherical graphene structure), carbon nanotube (cylindrical graphene structure), carbon nanohorn (cylindrical graphene structure), carbon nanobud, carbon nanofiber, carbon nanofoam, and carbyne.

In the present invention, the carbon material may be one or a combination of two or more selected from the group consisting of graphite, amorphous carbon, glassy carbon, graphene, fullerene, carbon nanotube, carbon nanohorn, carbon nanobud, carbon nanofiber, and carbon nanofoam. Preferably, the carbon material may be one or a combination of two or more selected from the group consisting of graphite, amorphous carbon, graphene, fullerene, carbon nanotube (preferably single-walled carbon nanotube), carbon nanohorn, carbon nanobud, carbon nanofiber, and carbon nanofoam. More preferably, the carbon material may be one or a combination of two or more selected from the group consisting of graphene, fullerene, carbon nanotube (preferably single-walled carbon nanotube), carbon nanohorn, carbon nanobud, carbon nanofiber, and carbon nanofoam.

(Chemical Bond)
According to one aspect of the present invention, it is preferable that the compound represented by the chemical formula I is bonded to the carbon material directly or via a bonding group (by a chemical bond, a physical bond, or a mixed bond thereof, preferably a chemical bond).

The bonding group is a divalent bonding group, and is, for example, -(C ₂ )m [m is 1 or more and 10 or less]-, -O-, -S-, -OCH ₂ -, -CH ₂ O-, -CO-, -COO-, -OCO-, -CO-S-, -S-CO-, -O-CO-O-, -CO-NH-, -NH-CO-, -SCH _{2 -, -CH 2 S-, -CF 2 O- ,} -OCF ₂ -, -CF ₂ S-, -SCF ₂ -, -CH=CH-COO-, -CH=CH-OCO-, -COO-CH=CH-, -OCO-CH=CH-, -COO-CH ₂ CH ₂ -, -OCO-CH ₂ CH ₂ -, -CH ₂ CH ₂ -COO-, -CH ₂ CH ₂ Examples thereof include one or a combination of two or more selected from the group consisting of -OCO-, _-COO - _CH2- , -OCO- _CH2- , _-CH2 -COO-, -CH2-OCO-, -CH=CH-, -N=N-, -CH=N-N=CH-, -CF=CF-, and -C≡C-.

(Sensing conditions)
The gas sensing material according to the present invention is subjected to an atmospheric pressure of 1 to 5 atmospheres, preferably 1 atmosphere or normal pressure. The relative humidity is preferably 10% to 100%, and 20% to 60%. The temperature is preferably -50°C to 100°C, and 10°C to 40°C. Gas is sensed and detected under a combination of these sensing conditions. In particular, in the present invention, the gas sensing material is used to detect gases emitted by respiratory exhalation in a living body.

(Gas: X group)
The gas to be sensed may be a nitrogen-based compound, an alcohol, a ketone, or an aldehyde, and is preferably ammonia, urea, acetone, formaldehyde, acetaldehyde, or an alcohol having 1 to 5 carbon atoms.

(Other gases: Y group)
In the present invention, the gas to be sensed is a thiol compound (mercaptan compound), specifically an alkyl mercaptan having 1 to 5 carbon atoms, preferably methyl mercaptan or ethyl mercaptan.

The gas sensing material of the present invention is capable of detecting gases at a level of 1 PPM or less under the above-mentioned wide range of sensing conditions, achieving excellent high sensitivity, and is capable of detecting gases at temperatures between -50°C and 100°C, particularly at room temperature, achieving high sensitivity at relative humidity between 10% and 100%, and making it possible to achieve thin films of the order of 500 nm or less and low resistance.

(Production example)
According to the first aspect of the present invention, the gas sensing material is obtained by mixing the compound represented by the [chemical formula I] with a carbon material. According to the second aspect of the present invention, the gas sensing material is obtained by forming a first layer or a second layer containing the compound represented by the [chemical formula I] and a first layer or a second layer containing a carbon material, respectively, and then forming a second layer. According to the third aspect of the present invention, the gas sensing material is obtained as a complex by preparing the compound represented by the [chemical formula I] and a carbon material, and chemically bonding the compound represented by the [chemical formula I] with the carbon material directly or via a bonding group. The details of the manufacturing method will be described later.

[Gas sensing material: Group X]
According to one aspect of the present invention, a gas sensing material is proposed which is composed of a polypyrrole derivative (represented by [Chemical Formula I]) represented by the following [Chemical Formula II] and carbon nanotubes.

In the above formula II,
A, B, S, and n are as defined in Formula I.

The gas sensing material represented by the above chemical formula II is formed by bonding the polypyrrole derivative represented by the above chemical formula I to a carbon nanotube (preferably a single-walled carbon nanotube) via a carbonyl group.

[Ammonia gas sensing material]
According to one aspect of the present invention, there is provided an (ammonia) gas sensing material, comprising:
The gas is ammonia,
In the above formula I and formula II,
A is a phenyl group;
B is a hydrogen atom, a halogen atom or a halogen compound;
S is a nitrogen atom or a nitrogen-containing functional group;
A, B, and S are different substances;
A gas sensing material is proposed, where n is 100 to 100,000.

In the above B, the halogen atom or halogen compound and the n are the same as defined in the above Chemical Formula I.
In the above S, the nitrogen atom-containing functional group can be one or a combination of two or more selected from the group consisting of an amino group, an imino group, a nitro group, a nitroso group, an azo group, a hydrazo group, a diazo group, and a cyano group, and preferably one or a combination of two or more selected from the group consisting of an amino group, an imino group, a nitro group, a nitroso group, an azo group, a hydrazo group, a diazo group, and a cyano group.

(Sensing conditions)
The gas sensing material according to the present invention has an atmospheric pressure of 1 to 5 atmospheres, preferably normal pressure, a relative humidity of 0% to 100%, preferably 20% to 60%, a temperature of -30°C to 100°C, preferably 10°C to 40°C, and ammonia gas is sensed and detected in these combinations. Particularly, in the present invention, it is used to sense gases emitted by respiratory exhalation in a living body.

[Acetone gas sensing material]
According to one aspect of the present invention, there is provided an (acetone) gas sensing material comprising:
The gas is acetone,
In the above formula I and formula II,
A is a methyl group or an oxygen atom;
B is a hydrogen atom or a sulfur atom;
S is ^-OH , -OH or -COOH;
A, B, and S are different substances;
A gas sensing material is proposed, where n is 100 to 100,000.

(Sensing conditions)
The gas sensing material has an atmospheric pressure of 1 to 5 atmospheres, preferably normal pressure, a relative humidity of 0% to 100%, preferably 20% to 60%, and a temperature of -30°C to 100°C, preferably 10°C to 40°C. In addition, ammonia gas is sensed and detected in these combinations. Particularly, in the present invention, it is used to sense gases emitted by respiratory exhalation in a living body.

[One embodiment of gas sensing material: Group Y]
[Gas sensing material]
According to one aspect of the present invention, there is provided a gas sensing material, comprising:
The present invention has a structure of a polypyrrole derivative and carbon nanotubes represented by the following [chemical formula III],
A gas sensing material is proposed in which the gas is acetone, ammonia, formaldehyde, or methyl mercaptan.

(Sensing conditions)
The gas sensing material according to the present invention has an atmospheric pressure of 1 to 5 atmospheres, preferably normal pressure, and a temperature of -30° C. to 100° C., preferably 10° C. to 40° C. In addition, in these combinations, each of the gases acetone, ammonia, formaldehyde, and methyl mercaptan is sensed and detected.

[(Acetone) Gas Sensing Material]
According to one aspect of the present invention, there is provided an (acetone) gas sensing material comprising:
The present invention has a structure of a polypyrrole derivative and carbon nanotubes represented by the following chemical formula IV:
A gas sensing material is proposed in which the gas is acetone.

(Sensing conditions)
The gas sensing material according to the present invention is subjected to an atmospheric pressure of 1 to 5 atmospheres, preferably normal pressure, and a temperature of -30° C. to 100° C., preferably 10° C. to 40° C. In addition, in these combinations, acetone is sensed and detected.

[Gas sensor: gas sensing element]
The present invention can propose a gas sensor (gas sensing element) comprising an electrode and the gas sensing material of the present invention.
The gas sensor according to the present invention can be constructed by forming the gas sensing material according to the present invention into a transparent thin film and sandwiching it between transparent electrodes, as shown in FIG.
The gas sensor according to the present invention is a main component of a gas sensing device, and is particularly used as one of the multi-function sensors for sensing gas, pressure, contact, temperature, etc.

[Method of manufacturing gas sensing material]
In one aspect of the present invention, there is provided a method for producing a gas sensing material according to the present invention, comprising the steps of:
(S1) preparing a conjugated polymer monomer, a carbon material, a transition metal salt catalyst, an emulsifier and/or a dispersant, and a functional organic substance;
(S2) A carbon material, a transition metal salt, and an emulsifier and/or a dispersant are mixed to obtain a dispersion,
(S3) adding the conjugated polymer monomer and the functional organic substance to the dispersion liquid and carrying out emulsion polymerization;
(S4) A production method is proposed, which includes purifying and separating the polymerization product to obtain the gas sensing material.

(S1)
In (S1), a conjugated polymer monomer, a carbon material, a transition metal salt catalyst, an emulsifier and/or a dispersant, and a functional organic substance are prepared.

<Monomers for conjugated polymers>
The monomer of the conjugated polymer is a monomer that constitutes a conjugated polymer synthesized by emulsion polymerization. The monomer of the conjugated polymer may be one or a combination of two or more selected from the group consisting of pyrrole, aniline, thiophene, 3,4-ethylenedioxythiophene, and thiophene, and is preferably pyrrole. The conjugated polymer may be one or a combination of two or more selected from the group consisting of polypyrrole, polyaniline, polythiophene, poly-3,4-ethylenedioxythiophene, and polythiophene, and is preferably polypyrrole.

Carbon Materials
The carbon material may be the same as that described in the section on gas sensing material. In the present invention, preferably, carbon nanotubes, more preferably single-walled carbon nanotubes, are used. The length of the carbon nanotubes is preferably 1 μm or more, more preferably 10 μm or more.

<Transition metal salt catalyst>
The transition metal salt catalyst is a catalyst that promotes emulsion polymerization of a pyrrole monomer. A specific example of the transition metal salt catalyst is one selected from the group consisting of iron chloride (FeCl ₃ ) and Fe(III) tosylate.

<Functional organic substances: organic compounds with gas-sensing functional groups>
The functional organic substance is a substance that introduces a gas sensing functional group into the gas sensing material. Examples of the functional organic substance include one or a combination of two or more selected from the group consisting of polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), polyacrylamide (PAA), dodecyl sulfonate, camphorsulfonic acid, and hexadecyltrimethylammonium salt.

By introducing a functional organic substance into a conjugated polymer as a specific functional group, it is possible to realize, for example, the functional groups A, B, and S (gas-sensing functional groups) in the above chemical formula I.

(S2)
In (S2), a carbon material, a transition metal salt, and an emulsifier and/or a dispersant are mixed to obtain a dispersion.

<Dispersion Liquid>
The dispersion can be obtained by dissolving and/or dispersing each material in water or a polar solvent. Dispersion can be carried out under various conditions, and in fact may be carried out in an air atmosphere at room temperature (about 25° C.).

(S3)
In (S3), the conjugated polymer monomer and the functional organic substance are added to the dispersion liquid and emulsion-polymerized.

(S3)
In (S3), the conjugated polymer monomer and the functional organic substance are emulsion-polymerized to include functional groups (gas-sensing functional groups) A, B and/or S (e.g., carboxyl groups, alcohol groups, ketone groups, or amine groups) on the surface of the conjugated polymer, thereby forming nanoparticles or nanorods of the conjugated polymer. On the surface of the nanoparticles or nanorods of the conjugated polymer, a gas-sensing material having a structure in which a positive charge and a gas-sensing functional group are connected (capped) while maintaining a chemical bond relationship can be generated. The gas-sensing material is generated as a particle shape having a diameter of 30 nm to 100 nm, a cylindrical shape having a diameter of 30 nm to 100 nm, and a length of 5 nm to 100 μm.

In (S3), the gas sensing material produced is as shown in Figures 2 and 3. As shown in Figure 2, the selectivity of a specific gas is determined by the structure of the gas sensing functional groups S and A in the surface structure of the nanoparticles, and the gas sensing functional groups may be, for example, a carboxy group, an alcohol group, a ketone group, an amine group, a phenyl group, and a group of a _C1-6 compound, and S and A are different substances and are characterized by having structural characteristics as optical isomers. In addition, the gas selectivity is determined by the structure of the gas sensing functional groups S and A in the surface structure of the gas sensing substrate (nanorod) shown in Figure 3.

In (S3), the emulsion polymerization reaction is carried out at a low temperature below room temperature, preferably below 0°C. By controlling the polymerization temperature, it is easy to form nano-sized particles or rods and improve the electrical conductivity.

(S4)
In (S4), the polymerization product is purified and separated to obtain the gas sensing material.
In (S4), the nano-structured gas sensing material obtained in (S3) is purified and separated, for example, by centrifugation to separate the remaining raw materials, by-products, etc. Also, preferably, the obtained nano-structured gas sensing material may be dispersed in a solvent (e.g., a tetrahydrofuran aqueous solution) and subjected to solid-liquid separation to remove impurities such as unreacted substances, and this process may be repeated two or three times. In fact, the unreacted substances dispersed in the tetrahydrofuran solution are individually separated in the upper layer, and the nano-structured gas sensing material can be separated in the lower layer due to the difference in specific gravity. Also, according to a preferred embodiment, by using a chloroform solvent, the unreacted polymer can be additionally removed, and a pure nano-structured gas sensing material can be obtained.
The obtained gas sensing material is produced as spherical particles having a diameter of 30 nm to 100 nm, or as rod-shaped structures having a diameter of 30 nm to 100 nm and a length of 5 nm to 100 μm.

(Optional additional process)
The obtained gas sensing material can be prepared as a dispersion by secondary dispersion in water or an organic solvent such as methanol, butanol, or isopropanol, and then coated onto a substrate to obtain a gas sensing thin film material.

[Gas sensing material obtained by the manufacturing method of gas sensing material]
In one aspect of the present invention, a gas sensing material (gas sensor) obtained by the method for producing a gas sensing material according to the present invention is proposed.
(S1) preparing a conjugated polymer monomer, a carbon material, a transition metal salt catalyst, an emulsifier and/or a dispersant, and a functional organic substance;
(S2) A carbon material, a transition metal salt, and an emulsifier and/or a dispersant are mixed to obtain a dispersion,
(S3) adding the conjugated polymer monomer and the functional organic substance to the dispersion liquid and carrying out emulsion polymerization;
(S4) A gas sensing material (gas sensor) obtained by purifying and separating the polymerization product.
Therefore, the method for producing the gas sensing material (gas sensor) is the same as that explained in the section "Method for producing the gas sensing material".

The present invention will be described using the following examples, but the scope of the present invention should not be interpreted as being limited to these examples. Furthermore, various aspects of the present invention disclosed in this specification can be easily implemented by those skilled in the art from these examples.

[Embodiment: Group X]
[Manufacture of gas sensing material]
(Gas sensing material 1)
In the reactor, 1% by weight of PVP (polyvinylpyrrolidone: molecular weight 1,300,000) was dissolved and dispersed in deionized water as a dispersant, and then 2.7 g of iron chloride (FeCl ₃ ) was added.
Next, 0.3 molar ratio of PA (phenylalanine) to pyrrole monomer was added to form micelles with a size of 60 μm. After adding 2% by weight of pyrrole monomer, the mixture was reacted by emulsion polymerization at 0° C. for 5 hours. After the reaction was completed, methanol was added in an amount approximately equal to that of the reaction solution, and the mixture was separated and collected, and the reaction product particles were then collected.
The synthesized nanostructured sensing material was subjected to secondary purification and separation by centrifugation to obtain a spherical nanoparticle structure (gas sensing material 1).
As shown in FIG. 4, this nanoparticle structure (gas sensing material 1) was a nanoparticle of conductive polymer polypyrrole with phenylalanine functional groups bound to the surface, and had an average diameter of about 50 nm to 80 nm.

(Gas sensing material 2)
Gas sensing material 2 was obtained in the same manner as gas sensing material 1, except that 0.003 wt % of single-walled carbon nanotubes (SWCNT) and hexadecyltrimethylammonium salt (HDTMA) were used as a dispersant, and polymerization was carried out while stirring at about 1000 rpm.
The gas sensing material 2 was a rod-shaped body having a size of 200 nm to 10 μm. The gas sensing material 2 was a conjugated carbon nanomaterial having a structure in which the surface of a single-walled carbon nanotube was covered with a conductive polymer polypyrrole having a phenylalanine functional group bonded to the surface, and the electron microscope photograph of this is as shown in FIG.

[Manufacture of gas detection sensor]
(Gas sensor 1)
As the carbon material, single-walled carbon nanotubes (SWCNTs) used in the manufacture of the gas sensing material 2 were used. SWCNTs and the gas sensing material 1 were formed on a comb-shaped electrode substrate, which had a metal comb-shaped electrode formed on a glass substrate, by spin coating at room temperature (25°C). The resistance value was adjusted to 10Ω or more and 1MΩ or less by adjusting the rotation speed to 500-7000 rpm, and the gas sensing sensor 1 was obtained.

(Gas sensor 2)
The dispersion of the gas sensing material 2 was formed into a film at room temperature (25° C.) by spin coating in the same manner as in the manufacture of the gas sensor 1. The resistance value was adjusted to 10Ω or more and 1MΩ or less by adjusting the rotation speed at 500 rpm to 7000 rpm, and the gas sensor 2 was obtained.

(Gas Sensor (Comparative Example 1))
As a comparative example 1, a gas sensor 1 from which only the carbon material was removed was used.

Example 1 [Gas sensor evaluation test (ammonia)]
(test)
The gas sensor 1 was installed in a gas introduction vessel, and the response of ammonia gas was measured at room temperature (25°C). 100 ppb ammonia gas diluted with pure air and pure air were alternately flowed. In both cases, the flow rate was 300 sccm and the relative humidity was 0%. The gas response was monitored by applying a voltage to the sensor using an electrometer to measure the current and monitor the resistance value. The change in resistance is shown in Figure 6.
On the other hand, for comparison, a gas sensor (Comparative Example 1) was used in which the carbon material was omitted from the gas sensing material 1, and the response to ammonia gas of the same concentration was evaluated under the same conditions as above. The results are shown in FIG.

(result)
As shown in Figure 6, it was confirmed that the resistance increases with ammonia and returns to normal with pure air. It was also confirmed that the change in resistance (ΔR) observed at this time was sufficiently large.
On the other hand, as shown in Fig. 7, it was confirmed that the noise increased and the sensitivity was low compared to the characteristics of the gas sensor of the present invention. Here, the sensitivity is expressed as S (%) = ΔR (resistance change value) / R0 (initial resistance value) × 100, and a decrease in sensitivity was observed because R0 was high.

Example 2 [Evaluation test of gas sensor (ammonia)]
(test)
The gas sensor 1 was used to evaluate the ammonia gas sensing performance.
The resistance change was confirmed when the ammonia concentration was 100 ppb, 500 ppb, and 1 ppm, and the amount of change was plotted against the concentration as an index called S. The results are shown in FIG.

(result)
In Fig. 8, the concentration at which the extrapolated S is higher than the noise level is called the limit of detection (LOD). In the present invention, a detection sensitivity of 20 ppb was obtained.

Example 3 [Evaluation test of gas sensor (ammonia)]
(test)
The gas sensor 2 was used to evaluate the detection performance of ammonia gas. The evaluation result at an ammonia concentration of 500 ppb is shown in Fig. 9. In addition, the resistance change at ammonia concentrations of 100 ppb, 500 ppb, and 1 ppm was confirmed, and the amount of change was plotted against the concentration as an index called S. The results are shown in Fig. 10.

(result)
In Fig. 10, the concentration at which the extrapolated S is higher than the noise level is called the limit of detection (LOD). In the present invention, a detection sensitivity of 20 ppb was obtained.
Both the gas sensor 1 and the gas sensor 2 showed high sensitivity with a detection limit of about 20 ppb for ammonia gas. Ammonia gas has three hydrogen atoms and one lone pair at the center of the nitrogen atom. When the gas sensor of Comparative Example 1 was used, ammonia gas reacts with the positive charge of the phenylalanine functional group, and as a result, the conductivity of the polaron structure of the doped polypyrrole is reduced, which is thought to be detected as a change in electrical signal.

On the other hand, in the gas detection sensor 1 (comprising gas sensing material 1 and carbon material) and gas detection sensor 2 (comprising gas sensing material 2) according to the present invention, the conductive polymer polypyrrole having phenylalanine functional groups that react specifically to ammonia gas and the carbon material that exhibits high conductivity form a complex that forms an electrical path, so it is believed that sensitivity is improved because the weak current change caused by gas adsorption in the functional group-containing conductive polymer polypyrrole can be sensitively read as an electrical signal by the highly conductive, low-noise carbon material.

Example 4 [Evaluation test of gas sensor (ammonia)]
(test)
The gas sensor 1 was used to measure the response of ammonia gas under humid conditions. The gas sensor 1 was attached to a container into which gas was introduced, and the response of ammonia gas was measured at room temperature. 500 ppb ammonia gas diluted with pure air and pure air were alternately flowed. The flow rate for both was 300 sccm. The humidity was measured at relative humidity of 50% and 70%. The results are shown in FIG. 11. It was confirmed that the resistance increases with ammonia and returns to normal with air.
In the present invention, even when the humidity was 50% and 70%, the same or higher detection sensitivity as that at 0% RH was obtained.

(result)
The results of using the gas sensor 1 and the results of using only the conductive polypyrrole having phenylalanine functional groups as a gas sensor (Comparative Example 1) are shown in Figure 12. In Figure 12, the dashed line shows the measured value using the gas sensor containing only the conductive polypyrrole having phenylalanine functional groups (Comparative Example 1). It was confirmed that the gas sensor according to the present invention has better humidity resistance than the conductive polypyrrole alone (Comparative Example 1).

Example 5 [Evaluation test of gas sensor (acetone)]
(test)
The gas sensor 1 was evaluated for its acetone gas sensing performance. The gas sensor 1 was attached to a container into which gas was introduced, and the response to acetone gas was measured at room temperature. 100 ppm acetone gas diluted with pure air and pure air were alternately flowed. In both cases, the flow rate was 300 sccm. The humidity was measured at 0% relative humidity. The acetone sensitivity was confirmed to be approximately 100 ppm. It was difficult to confirm a response at a lower acetone gas concentration. This result shows that there is selectivity for acetone.

(result)
From the results of the above examples, it can be seen that, when using the product manufactured by the gas sensor manufacturing method according to the present invention, a gas sensor (film) with significantly improved ammonia gas sensing characteristics can be manufactured even at room temperature below 40° C. Furthermore, according to the present invention, there is no change in sensitivity even at high humidity conditions of 80% or more, which shows a very effective effect required for commercialization.

[Embodiment: Group Y]
[Manufacture of gas sensing material]
(Gas sensing material 3)
In the reactor, 1% by weight of PVP (polyvinylpyrrolidone: molecular weight 1,300,000) was dissolved and dispersed in deionized water as a dispersant, and then 2.7 g of iron chloride (FeCl ₃ ) was added.
Next, LA (lactic acid) was added at a molar ratio of 0.3 to the pyrrole monomer to form micelles with a size of 60 μm. After adding 2% by weight of pyrrole monomer, the reaction was carried out by emulsion polymerization at 0° C. for 5 hours. After the reaction was completed, methanol was added in an amount approximately equal to that of the reaction solution, and the reaction product particles were separated and collected.
The synthesized nanostructured sensing material was subjected to secondary purification and separation by centrifugation to obtain a spherical nanoparticle structure (gas sensing material 3).

(Gas sensing material 4)
Gas sensing material 4 (structure represented by [chemical formula III]) was obtained in the same manner as gas sensing material 3, except that 0.003 wt % of single-walled carbon nanotubes (SWCNT) and hexadecyltrimethylammonium salt (HDTMA) were used as a dispersant and polymerization was carried out while stirring at about 1000 rpm.
The gas sensing material 4 was a rod-shaped body having a size of 200 nm to 10 μm. The gas sensing material 4 was obtained as a conjugated carbon nanomaterial having a structure in which a conductive polymer polypyrrole having a lactic acid functional group bonded to the surface covers the surface of a single-walled carbon nanotube.

(Gas sensing material 5)
In the reactor, 1% by weight of PVP (polyvinylpyrrolidone: molecular weight 1,300,000) was dissolved and dispersed in deionized water as a dispersant, and then 2.7 g of iron chloride (FeCl ₃ ) was added.
Next, 0.3 molar ratio of PLA (phenyllactic acid) to pyrrole monomer was added to form micelles with a size of 60 μm. After adding 2% by weight of pyrrole monomer, the reaction was carried out by emulsion polymerization at 0°C for 5 hours. After the reaction was completed, methanol was added in an amount approximately equal to that of the reaction solution, and the reaction product particles were separated and collected.
The synthesized nanostructured sensing material was subjected to secondary purification and separation by centrifugation to obtain a spherical nanoparticle structure (gas sensing material 5).

(Gas sensing material 6)
Gas sensing material 6 (structure represented by [chemical formula IV]) was obtained in the same manner as gas sensing material 5, except that 0.003 wt % of single-walled carbon nanotubes (SWCNT) and hexadecyltrimethylammonium salt (HDTMA) were used as a dispersant and polymerization was carried out while stirring at about 1000 rpm.
The gas sensing material 6 was a rod-shaped body having a size of 200 nm to 10 μm. The gas sensing material 4 was obtained as a conjugated carbon nanomaterial having a structure in which a conductive polymer polypyrrole having a phenyllactic acid functional group bonded to the surface covers the surface of a single-walled carbon nanotube.

[Manufacture of gas detection sensor]
(Gas sensor 3)
The dispersion of the gas sensing material 4 was drop-cast onto a comb-shaped electrode substrate having a metal comb-shaped electrode formed on a glass substrate, and a film was formed at room temperature (25° C.). The resistance value was adjusted to 10Ω or more and 100MΩ or less by adjusting the number of drop-casts, and the gas sensing sensor 3 was obtained.

(Gas sensor 4)
The dispersion of the gas sensing material 6 was drop-cast onto a comb-shaped electrode substrate having a metal comb-shaped electrode formed on a glass substrate, and a film was formed at room temperature (25° C.). The resistance value was adjusted to 10Ω or more and 100MΩ or less by adjusting the number of drop-casts, and the gas sensing sensor 4 was obtained.

Example 6 [Evaluation test of gas sensor (acetone)]
(test)
The gas sensor 3 was attached to a gas introduction vessel, and the response of acetone gas was measured at room temperature (25°C). Pure air and 50 ppb acetone gas diluted with pure air were alternately flowed. In both cases, the flow rate was 600 sccm and the relative humidity was 0%. The gas response was monitored by applying a voltage to the sensor using an electrometer to measure the current and monitor the resistance value. The resistance change was as shown in Figure 13.

(result)
As shown in Fig. 13, the resistance was confirmed to decrease with acetone and to return to normal with pure air. The signal was reproducible over several cycles, and the signal-to-noise (S/N) ratio was 5 or higher.

Example 7 [Evaluation test of gas sensor (acetone)]
(test)
The gas sensor 4 was attached to a gas introduction vessel, and the response of acetone gas was measured at room temperature (25°C). Pure air and 50 ppb of acetone gas diluted with pure air were alternately flowed. In both cases, the flow rate was 600 sccm, and the relative humidity was 0%. The gas response was monitored by applying a voltage to the sensor using an electrometer to measure the current and monitor the resistance value. The resistance change was as shown in Figure 14.

(result)
As shown in Fig. 14, it was confirmed that the resistance was decreased by acetone and returned to normal by pure air. This signal was reproducible over several cycles, and the signal-to-noise (S/N) ratio was 10 or more.

Example 8 [Evaluation test of gas sensor (ammonia)]
(test)
The gas sensor 3 was installed in a gas introduction vessel, and the response of ammonia gas was measured at room temperature (25°C). Pure air and 1 ppm ammonia gas diluted with pure air were alternately flowed. In both cases, the flow rate was 300 sccm and the relative humidity was 0%. The gas response was monitored by applying a voltage to the sensor using an electrometer to measure the current and monitor the resistance value. The resistance change was as shown in Figure 15.
Similarly, 100 ppb ammonia gas diluted with pure air and pure air were alternately flowed. The flow rate of both was 300 sccm and the relative humidity was 0%. The gas response was monitored by applying a voltage to the sensor using an electrometer to measure the current and the resistance value. The resistance change was as shown in Figure 16.

(result)
15 and 16, it was confirmed that the resistance increased with ammonia and returned to normal with pure air. The signal was reproducible over several cycles, with the signal-to-noise (S/N) ratio at 1 ppm ammonia being 60 or more and the signal-to-noise (S/N) ratio at 100 ppb ammonia being 10 or more.

Example 9 [Evaluation test of gas sensor (formaldehyde)]
(test)
The gas sensor 3 was attached to a gas introduction vessel, and the response of formaldehyde gas was measured at room temperature (25°C). 100 ppb formaldehyde diluted with pure air and pure air were alternately flowed. In both cases, the flow rate was 300 sccm and the relative humidity was 0%. The gas response was monitored by applying a voltage to the sensor using an electrometer to measure the current and monitor the resistance value. The resistance change is shown in Figure 17.
Similarly, 50 ppb formaldehyde diluted with pure air and pure air were alternately flowed. The flow rate of both was 300 sccm and the relative humidity was 0%. The gas response was monitored by applying a voltage to the sensor using an electrometer to measure the current and the resistance value. The resistance change was as shown in Figure 18.

(result)
17 and 18, we were able to confirm the phenomenon that the resistance is reduced by formaldehyde and restored by pure air. This signal was reproducible over several cycles, and we were able to confirm high performance, with the sensitivity S (%) = ΔR (resistance change value) / R0 (initial resistance value) × 100 being 0.2 or more for a concentration of 50 ppb, and the signal-to-noise (S/N) ratio being 10 or more.

Example 10 [Evaluation test of gas sensor (methyl mercaptan)]
(test)
The gas sensor 3 was installed in a gas introduction vessel, and the response of methyl mercaptan gas was measured at room temperature (25°C). Pure air diluted 200 ppb methyl mercaptan and pure air were alternately flowed. In both cases, the flow rate was 300 sccm and the relative humidity was 0%. The gas response was monitored by applying a voltage to the sensor using an electrometer to measure the current and monitor the resistance value. The resistance change was as shown in Figure 19.

(result)
As shown in Fig. 19, it was confirmed that the resistance was reduced by methyl mercaptan and restored by pure air. This signal was reproducible over several cycles, and high performance was confirmed, with the sensitivity S (%) = ΔR (resistance change value) / R0 (initial resistance value) × 100 being 0.3 or more for a concentration of 200 ppb, and the signal-to-noise (S/N) ratio being 20 or more.

The gas sensing material of the present invention can achieve high sensitivity, high selectivity, wide range of use mobility, compact size, and low power consumption. The manufacturing method of the present invention can produce a gas sensing material that is simple, compact, and inexpensive. As a result, the gas sensing material of the present invention can be used for a wide variety of applications.

Claims (12)

A gas sensing material, comprising:
The present invention comprises a polypyrrole derivative represented by the following chemical formula I and a carbon material ,
The gas sensing material , wherein the gas is ammonia .

[Chemical Formula I]
[In the above chemical formula I,
A is a phenyl group;
B is a hydrogen atom, a halogen atom or a halogen compound;
S is a nitrogen atom or a nitrogen-containing functional group ;
A, B, and S are different substances;
n is 100 or more and 100,000 or less. A gas sensing material, comprising:
The coating composition comprises at least a first layer and a second layer,
Either the first layer or the second layer comprises a polypyrrole derivative represented by the following chemical formula I:
the other of the first layer or the second layer comprises a carbon material ;
A gas sensing material , wherein the gas is acetone .

[Chemical Formula I]
[In the above chemical formula I,
A is an alkyl group having 1 to 10 carbon atoms or a phenyl group,
B is a hydrogen atom ,
S is a nitrogen atom, an oxygen atom, or a polar compound composed of these atoms;
A, B, and S are different substances;
n is 100 or more and 100,000 or less. 3. The gas sensing material according to claim 1 or 2, wherein the carbon material is one or a combination of two or more selected from the group consisting of natural or synthetic (cubic) diamond , lonsdaleite, graphite, amorphous carbon, glassy carbon, graphene, fullerene, carbon nanotube, carbon nanohorn, carbon nanobud, carbon nanofiber, carbon nanofoam, and carbyne. 3. The gas sensing material according to claim 1 , wherein the compound represented by the formula I is bonded to the carbon material directly or via a bonding group. The bonding group is a divalent bonding group, and is, for example, -(C ₂ )m (m is 1 or more and 10 or less)-, -O-, -S-, -OCH ₂ -, -CH ₂ O-, -CO-, -COO-, -OCO-, -CO-S-, -S-CO-, -O-CO-O-, -CO-NH-, -NH-CO-, -SCH _{2 -, -CH 2 S-, -CF 2 O- ,} -OCF ₂ -, -CF ₂ S-, -SCF ₂ -, -CH=CH-COO-, -CH=CH-OCO-, -COO-CH=CH-, -OCO-CH=CH-, -COO-CH ₂ CH ₂ -, -OCO-CH ₂ CH ₂ -, -CH ₂ CH ₂ -COO-, -CH ₂ CH ₂ The gas sensing material according to claim 4, which is one or a combination of two or more selected from the group consisting of -OCO-, -COO-CH ₂ -, -OCO _- CH2-, -CH ₂ -COO-, -CH 2 -OCO-, -CH=CH-, -N=N-, -CH=N-N=CH-, -CF=CF-, and -C≡C-. A gas sensing material, comprising:
A gas sensing material having a structure of a polypyrrole derivative and carbon nanotubes, represented by the following chemical formula II.
[Chemical Formula II]
[In the above chemical formula II,
A is an alkyl group having 1 to 10 carbon atoms or a phenyl group,
B is a hydrogen atom, a halogen atom or a halogen compound;
S is a sulfur atom, a nitrogen atom, an oxygen atom, or a polar compound composed of these atoms;
A, B, and S are different substances;
n is 100 or more and 100,000 or less. A gas sensing material, comprising:
The present invention comprises a polypyrrole derivative represented by the following chemical formula I and a carbon material ,
A gas sensing material , wherein the gas is a thiol compound .

[Chemical Formula I]
[In the above chemical formula I,
A is an alkyl group having 1 to 10 carbon atoms or a phenyl group,
B is a hydrogen atom, a halogen atom or a halogen compound;
S is a sulfur atom, a nitrogen atom, an oxygen atom, or a polar compound composed of these atoms;
A, B, and S are different substances;
n is 100 or more and 100,000 or less. A gas sensing material, comprising:
The coating composition comprises at least a first layer and a second layer,
Either the first layer or the second layer comprises a polypyrrole derivative represented by the following chemical formula I:
the other of the first layer or the second layer comprises a carbon material ;
A gas sensing material, wherein the gas is a thiol compound.

[Chemical Formula I]
[In the above chemical formula I,
A is an alkyl group having 1 to 10 carbon atoms or a phenyl group,
B is a hydrogen atom, a halogen atom or a halogen compound;
S is a sulfur atom, a nitrogen atom, an oxygen atom, or a polar compound composed of these atoms;
A, B, and S are different substances;
n is 100 or more and 100,000 or less. The gas sensing material according to any one of claims 1 to 8 , which senses at 1 atmospheric pressure and at a relative humidity of 10% to 100%. The gas sensing material according to any one of claims 1 to 9 , which senses at 1 atmospheric pressure and at a temperature of -50°C or higher and 100°C or lower. 1. A gas sensor comprising:
The device comprises a positive electrode, a negative electrode, and a gas sensing material,
A gas sensor, wherein the gas sensing material is as defined in any one of claims 1 to 10 . A method for producing a gas sensing material, comprising the steps of:
(S1) preparing a conjugated polymer monomer, a carbon material, a transition metal salt catalyst, an emulsifier and/or a dispersant, and a functional organic substance;
(S2) A carbon material, a transition metal salt, and an emulsifier and/or a dispersant are mixed to obtain a dispersion,
(S3) adding the conjugated polymer monomer and the functional organic substance to the dispersion liquid and carrying out emulsion polymerization;
(S4) purifying and separating the polymerization product to obtain the gas sensing material.