KR20100008550A - A gas sensor of metaloxide including catalyst and a fbrication method thereof - Google Patents

Abstract

PURPOSE: A metal oxide gas sensor having a catalyst and a manufacturing method thereof are provided to improve high sensitive peculiarity and selectivity by distributing metal catalysts of a nanometer size uniformly. CONSTITUTION: A metal oxide gas sensor having a catalyst comprises a sensor substrate and sensor materials. The sensor materials compressed and formed on one surface of the sensor substrate. The sensor materials have a porous thin layer. The porous thin layer has a nanofiber network structure which comprises metal catalyst particles(12) and nano particles(11). The metal catalyst particles are distributed in the surface and inside of the nanofiber network structure. The nanofiber network structure has a flat belt form. The average diameter of the metal catalyst particles is 1-100nm.

Description

A metal oxide gas sensor comprising a catalyst and a method of manufacturing the same {A GAS SENSOR OF METALOXIDE INCLUDING CATALYST AND A FBRICATION METHOD THEREOF}

The present invention relates to a gas sensor and a method for manufacturing the same, and more particularly, to a gas sensor and a method for producing the same comprising a metal catalyst and a metal oxide layer capable of screening hazardous environmental gases with high sensitivity.

As environmental pollution becomes serious, high sensitivity that can measure environmental harmful substances (HC, alcohol, NOx, SOx, NH ₃ , CO, CO ₂ , DMMP, phenol, acetone, formaldehyde, etc.) at concentration below 1 ppm There is a growing interest in sensors. Especially in confined areas such as subways and public buildings, and in densely populated areas, it is important to have a system that can measure air pollution continuously in real time and warn you when the limit is exceeded. You should also have.

Metal oxides (ZnO, SnO ₂ , WO ₃ , TiO ₂ Etc.) materials having a band gap between 3.0 and 4.8 eV may have semiconductor characteristics. When gas (NOx, CO, H ₂ , HC, SOx, etc.) is adsorbed on the surface of the semiconducting metal oxide, the resistance of the metal oxide is changed through the oxidation / reduction process. The greater the change in resistance, the better the sensing characteristics of the sensor containing the metal oxide. For this purpose, it is important for the metal oxide to have a wider surface area and to have a porous structure in which harmful gases can move well on the surface of the metal oxide.

In addition, in order to apply the sensor to the vehicle's air quality sensor (Air Quality Sensor) it is important to quickly check the external harmful gas. For this purpose, the response speed of the sensor should be fast. Also important is the selectivity that can clearly distinguish when multiple hazardous gases are present at the same time. This can be said to secure Sensitivity, Selectivity, Speed and Stability represented by 4S.

In the gas sensor field, these chemical sensors are widely used in the form of bulk and thick films, but recently, as the demand for miniaturization and integration increases, a thin film capable of detecting accurate and sub-ppm levels can be detected. And MEMS-based sensor devices.

In particular, the most ideal sensor in terms of ultra-high sensitivity and fast sensor response speed is a sensor using metal oxide nanowires having a one-dimensional structure. However, in the case of a sensor using individual nanowires, high sensitivity is obtained, but noise due to instability of contact resistance is generated, making it difficult to manufacture a highly reproducible device. In addition, electrical contact and assembly of individual nanowires must be addressed.

As a result, fabrication of the sensor using a network of nanowires, rather than the fabrication of a sensor device using single nanowires, can ensure high reproducibility and stability of the electrical signal. In particular, it is necessary to use a metal catalyst together to further increase sensitivity and to provide selectivity of the sensor using the nanowire network.

The present invention has been made to solve these conventional problems, the object of the present invention,

First, the nanometer-sized metal catalyst is uniformly distributed on and inside the metal oxide nanofiber network to provide an ultra-sensitive sensor having high sensitivity and high selectivity.

Second, to provide a very high sensitivity of the mechanical, thermal, and electrical stability by greatly increasing the adhesion between the substrate on which the sensor electrode is formed and the metal oxide containing the metal catalyst,

Third, to provide a simple method of manufacturing a sensor having the above characteristics in a low-cost process and high yield.

In order to achieve these purposes,

The present invention,

It includes a substrate formed with a sensor electrode (hereinafter referred to as a "sensor substrate") and a sensor material formed on one surface of the sensor substrate,

The sensor material provides a gas sensor comprising a metal catalyst particle and a porous thin layer of a metal oxide having a network structure of nano-fibers including metal oxide nanoparticles.

In addition, the metal catalyst particles of the sensor material provides a gas sensor, characterized in that distributed on the surface and the inside of the network structure of the nano-fiber (Nano-fiber) including the nanoparticles of the metal oxide.

In addition, the present invention,

Spinning a solution containing a metal catalyst precursor, a metal oxide precursor, a polymer, and a solvent on the sensor substrate to form a composite fiber;

Compressing the composite fiber on the sensor electrode by thermocompression or thermocompression; And

It provides a gas sensor manufacturing method comprising the step of removing the polymer from the composite fiber by heat-treating the compressed composite fiber.

The gas sensor manufactured according to the present invention has a structure in which particles of the metal catalyst are uniformly distributed on the surface and inside of the nanofiber network structure including fine nanoparticles of metal oxides, so that the specific surface area is greatly increased. It is possible to further enhance the gas detection characteristics by the metal catalyst.

In addition, various kinds of metal oxides and metal catalysts may be variously changed to simultaneously provide high sensitivity and selectivity of the sensor to various gases.

In addition, the adhesion between the sensor substrate and the thin metal oxide nanofiber network layer including the metal catalyst may be greatly improved through thermal compression or thermal pressurization to manufacture a sensor having high electrical and mechanical stability.

In addition, the thickness of the metal oxide layer, which is a sensor sensing material layer, can be easily adjusted by adjusting the radiation time.

Hereinafter, the present invention will be described in detail.

I. Gas sensor

The gas sensor of the present invention includes a sensor substrate on which an electrode capable of measuring a change in resistance is formed and a sensor material formed on the sensor substrate.

The sensor electrode is platinum (Pt), gold (Au), palladium (Pd), iridium (Ir), silver (Ag), ruthenium (Ru), nickel (Ni), stainless steel (STS), aluminum (Al), 1 type selected from the group consisting of molybdenum (Mo), chromium (Cr), copper (Cu), titanium (Ti), tungsten (W), ITO (In doped SnO ₂ ) and FTO (F doped SnO ₂ ) Alternatively, two or more kinds of electrodes are preferably disposed on a substrate, preferably a ceramic substrate, an alumina (Al ₂ O ₃ ) substrate, a silicon (Si) substrate and a silicon oxide (SiO ₂ ) substrate on which an insulating layer is deposited. The sensor substrate preferably includes a substrate in which the sensor electrode is patterned in the form of an interdigital electrode.

In the gas sensor of the present invention, at least two sensor substrates are arranged, and different sensor materials may be formed on the at least two sensor substrates.

Figure 1a is a schematic diagram showing a network of nanofibers comprising metal catalyst particles in accordance with the present invention, consisting of metal oxide nanoparticles.

Referring to FIG. 1A, the sensor material of the present invention includes a metal oxide layer having a nanofiber network structure including metal catalyst particles and nanoparticles of metal oxide, wherein the metal catalyst particles are nanofiber network. Evenly located on the surface and inside of the structure. The metal oxide layer is preferably in the form of a flat belt.

On the other hand, in the sensor material of the present invention, since the metal oxide constituting the nanofiber network structure is present in nanoscale in the ratio of the surface depletion layer due to the spillover effect by the metal catalyst particles, the surface of the metal oxide surface The depletion layer ratio may be maximized to increase the reactivity of the metal oxide nanoparticles (see FIG. 1B).

The metal catalyst is preferably one selected from the group consisting of copper (Cu), iron (Fe), palladium (Pd), silver (Ag), platinum (Pt), nickel (Ni) and gold (Au) or It contains 2 or more types.

The metal oxide may be one kind or two or more kinds selected from the group consisting of SnO ₂ , TiO ₂ , ZnO, VO ₂ , In ₂ O ₃ , NiO, MoO ₃ , SrTiO ₃ , Fe ₂ O ₃ , WO ₃ and CuO. have. Nanoparticles of the metal oxide is preferably in the grain (grain) or rod (rod) shape.

In the ratio of the metal catalyst and the metal oxide of the gas sensor of the present invention, when the metal atom of the metal catalyst satisfies 0.1 to 50 at% of the total metal atom (sum of the metal atom of the metal catalyst and the metal atom of the metal oxide), The effect of the gas sensor of the present invention can be achieved.

The average diameters of the metal catalyst particles and the metal oxide nanoparticles are each 1 to 100 nm, and the average diameter of the nanofibers is preferably 50 to 3000 nm. If the above range is satisfied, metal catalyst particles may be uniformly distributed on the surface and inside of the nanofiber network structure including nanoparticles of metal oxides, and an ultra-high sensitivity sensor having high sensitivity and selectivity may be realized.

II. Manufacturing method of gas sensor

Method of manufacturing a gas sensor of the present invention comprises the steps of spinning a solution containing a metal catalyst precursor, a metal oxide precursor, a polymer and a solvent on a sensor substrate on which an electrode capable of measuring a change in resistance to form a composite fiber; Pressing the composite fiber on the sensor substrate by thermal compression or thermal pressing; And removing the polymer from the composite fiber by heat treating the compressed composite fiber.

Hereinafter, the manufacturing method of the gas sensor of the present invention will be described in detail for each step.

1. Forming a composite fiber on the sensor substrate

1-1. Preparation of Spinning Solutions

2 is a flowchart illustrating a method of manufacturing the gas sensor of the present invention.

For spinning, a mixed solution containing a metal catalyst precursor, a metal oxide precursor, a polymer, and a solvent (hereinafter referred to as "spinning liquid") is prepared.

The metal catalyst precursor is a material capable of becoming a metal catalyst after spinning and heat treatment of the spinning solution, preferably copper (Cu), iron (Fe), palladium (Pd), silver (Ag), platinum (Pt), nickel It is a precursor containing 1 type (s) or 2 or more types chosen from the group which consists of (Ni) and gold (Au). The metal catalyst precursor is not limited to a specific precursor as long as it contains the metal component and is dissolved in a polymer and a solvent to be spun. Metal catalyst precursors preferably include, but are not limited to, acetate, sulfide, and chloride salts of the metals. More specific examples include hydrogen tetrachloroaurate (III) Hydrate: HAuCl ₄ nH ₂ O, and Palladium (II) acetate trimer: [Pd (C ₂ H ₃ O ₂ ) ₂ ] ₃ ), silver nitrate (Silver Nitrate Solution, AgNO ₃ ), silver chloride (Silver Chloride, AgCl).

The metal oxide precursor is a material capable of becoming a metal oxide after spinning and heat treatment of the spinning solution, preferably tin (Sn), titanium (Ti), zinc (Zn), vanadium (V), indium (In), nickel (Ni), molybdenum (Mo), strontium (Sr), iron (Fe), tungsten (W), copper (Cu), calcium (Ca), niobium (Nb), cobalt (Co), and gallium (Ga) It is a precursor containing one or two or more components selected from the group consisting of. The metal oxide precursor may preferably form oxides of SnO ₂ , TiO ₂ , ZnO, VO ₂ , In ₂ O ₃ , NiO, MoO ₃ , SrTiO ₃ , Fe ₂ O ₃ , WO ₃ or CuO after spinning and heat treatment. As far as possible, no constraint is placed on specific precursors.

In the ratio of the metal catalyst and the metal oxide of the gas sensor, various combinations provided that the metal atom of the metal catalyst satisfies 0.1 to 50 at% of the total metal atom (the sum of the metal atoms of the metal catalyst and the metal oxide of the metal oxide). The combination of the metal catalyst precursor and the metal oxide precursor can be used.

The polymer increases the viscosity of the spinning solution to form a fibrous phase during spinning, and controls the structure of the spun fiber by the compatibility of the metal catalyst precursor and the metal oxide precursor. The polymer is polyurethane, polyetherurethane, polyurethane copolymer, cellulose acetate, cellulose acetate butylate, cellulose acetate propionate, polymethylmethacrylate (PMMA), polymethylacrylate (PMA), polyacryl copolymer , Polyvinylacetate (PVAc), polyvinylacetate copolymer, polyvinyl alcohol (PVA), polyfuryl alcohol (PPFA), polystyrene, polystyrene copolymer, polyethylene oxide (PEO), polypropylene oxide (PPO), polyethylene oxide Copolymers, polypropylene oxide copolymers, polycarbonate (PC), polyvinylchloride (PVC), polycaprolactone, polyvinylpyrrolidone (PVP), polyvinyl fluoride, polyvinylidene fluoride copolymer and It is preferable that it is 1 type, or 2 or more types chosen from the group which consists of polyamides. However, the polymer is not limited thereto, and is not particularly limited as long as it can be formed into nanofibers by spinning.

The solvent may be one selected from the group consisting of dimethylformamide (DMF), acetone, detrahydrofuran, toluene, water and mixtures thereof. However, the present invention is not limited thereto.

In the spinning solution of the present invention, an additive may be added for smooth spinning. The additive is preferably acetic acid, cetyltrimethyl ammonium bromide (CTAB), or the like.

1-2. Preparation of Precursor-Polymer Composite Fiber Including Metal Catalyst Precursor and Metal Oxide Precursor

Subsequently, the spinning solution obtained above is spun onto the substrate on which the sensor electrode is formed. Due to the spinning, a network of super-fine (including metal catalyst precursor and metal oxide precursor) precursor-polymer composite fibers is formed by a phase separation or mutual mixing process between the metal catalyst precursor and the metal oxide precursor and the polymer.

In order to form a network of the composite fibers, known electrospinning, melt-blown, flash spinning or electrostatic melt-blown methods Spinning may be performed using one selected from the group consisting of: Among these, it is preferable to use the electrospinning method.

3 illustrates the electrospinning method. When using the electrospinning method, by applying a voltage of 7 ~ 20㎸ by controlling the discharge rate of the solution to 10 ~ 50㎛ / minute it can be produced an ultra-fine fibers having an average diameter of 50 ~ 3000nm of the composite fiber. . Electrospinning conditions, such as the distance between the other tip and the substrate, are a common range. The electrospinning is preferably carried out until the composite fiber layer is formed on the sensor substrate with a thickness of 0.1 ~ 10㎛. By controlling the emission time, the thickness of the metal oxide layer, which is a sensor sensing material layer, can be easily adjusted.

Meanwhile, in the gas sensor of the present invention, at least two sensor substrates are arranged, and different sensor solutions may be formed by spinning different spinning solutions on the at least two sensor substrates.

2. Thermo-compression or thermo-pressurization step

Subsequently, the spun composite fiber is thermally compressed at a temperature equal to or higher than the glass transition temperature of the polymer to be pressed onto the sensor substrate.

If the partial and total melting of the polymer can be induced without pressing, the composite fiber may be pressed onto the sensor substrate by applying heat at a temperature slightly higher than the glass transition temperature of the polymer or by thermally pressurizing it using hot compressed air. . At this time, in order to suppress the sudden volatilization of the polymer, it may be subjected to a heat treatment step by step at a low temperature (for example, 100 ℃, 200 ℃) after the heat pressurization at a high temperature.

The pressure, temperature, and time of the thermal compression or thermal pressurization are appropriately selected in consideration of the type of polymer used, the glass transition temperature, and the like. In consideration of the type of polymer used and the glass transition temperature, the pressure range may be selected from 0.01 MPa to 10 MPa, and the compression time may be selected from 10 seconds to 10 minutes. More preferably, the pressure is 0.1 MPa for 30 seconds.

By the thermal compression or thermal pressurization, the flow between the metal catalyst precursor and the metal oxide precursor and the polymer separated from the phase during spinning is suppressed, and after the heat treatment, the nanoparticles include nanometer-sized metal catalyst particles and metal oxide nanoparticles. The thermocompression or thermocompression step of the fiber network partially or entirely melts the polymer in the composite fiber to increase the adhesion between the composite fiber and the sensor substrate. In contrast, nanofibers not subjected to thermal compression are easily detached from the substrate after heat treatment.

3. Manufacturing Step of Metal Oxide Nanofiber Network Including Metal Catalyst

Subsequently, the composite fiber compressed to the sensor substrate is heat treated to remove the polymer. The heat treatment temperature and time are determined in consideration of the crystallization and firing temperature of the metal oxide used. The heat treatment may be performed in a temperature range of 400 ~ 800 ℃ according to the type of the metal oxide precursor.

When the sensor substrate on which the composite fiber including the metal catalyst precursor and the metal oxide precursor is formed is thermally compressed or thermally pressed, the heat treatment may be performed to form a metal oxide layer having a unique structure including a metal catalyst and greatly improving specific surface area and pore density. Can be. As a result, sensitivity to gas is greatly improved, and an ultra-high sensitivity sensor having high selectivity with respect to gas can be obtained according to the type and content of metal catalyst used.

The metal oxide layer formed on one surface of the sensor substrate is a porous thin layer, and includes a nanometer-sized metal catalyst particle, and has a network structure of flat belt-shaped nanofibers including metal oxide nanoparticles. Due to this structure, the specific surface area (reaction area) is maximized, and a fast gas reaction is obtained by the porous structure and the metal catalyst nanoparticles. In addition, the adhesion between the thin metal oxide layer and the sensor substrate is greatly improved due to thermal compression (or thermal pressurization) and heat treatment.

The average diameters of the metal catalyst particles and the metal oxide nanoparticles are each 1 to 100 nm, and the average diameter of the nanofibers is preferably 50 to 3000 nm. The size of the metal catalyst particles and the metal oxide nanoparticles can be controlled by the amount of each precursor added and the heat treatment temperature used.

The metal oxide nanoparticles may have a crystalline structure and an amorphous structure depending on the heat treatment temperature.

The metal catalyst particles may be in the form of crystalline metals or precious metals which have been partially oxidized.

Hereinafter, the present invention will be described in detail with reference to examples, but these examples are only presented to more clearly understand the present invention, and are not intended to limit the scope of the present invention. It will be determined within the scope of the technical spirit of the claims.

[ Example  One] Gold catalyst precursor  Precursor-Polyvinylacetate Composite Fiber Containing Tin Oxide Precursor Thermocompression Post-heat treatment  through Au - SnO ₂  Composition Nanofiber  Network manufacturing

A polymer solution in which 0.4 g of polyvinylacetate (Mw: 1,000,000) was dissolved in 2.5 ml of dimethylformamide and dissolved for about a day, and hydrogen tetrachloroaurate (III) Hydrate: HAuCl ₄ nH ₂ O, a metal catalyst precursor ) And tin acetate (Sn (CH ₃ COO) ₄ ), which is a metal oxide precursor, were mixed with each other in a solution of 2.5 ml of dimethylformamide (DMF) at a ratio of 0.101 g: 0.899 g, respectively, to prepare a spinning solution.

The prepared spinning solution was transferred to a syringe, mounted on an electrospinning apparatus, and a voltage was applied between the tip of the syringe tip and the lower substrate to obtain ultrafine composite fibers. At this time, the voltage was 14 kV, the flow rate was 15 µl / min, and the distance between the tip and the substrate was 10 cm. The sensor substrate is made of alumina (Al ₂ O ₃ ) in which Au is formed of an interdigital electrode (finger width: 200 μm, finger spacing: 200 μm, finger length: 8 mm, finger pair: 7). The substrate was used. The SEM photograph of the obtained ultrafine composite fiber is shown in FIG. 4A.

The sensor substrate on which the precursor-polymer composite fiber including the electrospun gold catalyst precursor and the tin oxide precursor were laminated was thermally pressed for 30 seconds at a pressure of 0.1 MPa in a press heated to 120 ° C. At this time, the surface structure was also changed according to the applied pressure. In addition, different thermal pressurization temperatures could be determined depending on the polymer used. 4b shows a structure in which precursor-polymer composite fibers including a gold catalyst precursor and a tin oxide precursor are connected to each other through the overall melting process of the polymer (PVAc) occurring during the thermocompression bonding process.

After the thermal compression process, heat treatment was performed at 450 ℃ for 30 minutes.

4c shows that after undergoing thermal compression and heat treatment at 450 ° C. for 30 minutes, a continuous flat belt-shaped nanofiber network consisting of fine nanoparticles of tin oxide is obtained. It can be seen that fine nanometer-sized gold catalyst particles are evenly distributed on the surface of the continuous nanofiber network.

The average diameter of the nanofibers of tin oxide (SnO ₂ ) including the gold catalyst heat-treated at 450 ℃ is 200 ~ 1000nm, the average size of the tin oxide nanoparticles constituting the nanofiber is 10nm, of the gold catalyst particles The average size is 30 nm.

[ Example 2 ] Gold catalyst precursor  Precursor-Polyvinylacetate Composite Fiber Containing Tin Oxide Precursor Thermocompression  Through heat treatment Au - SnO ₂  Composition Nanofiber  Network manufacturing

0.502 g and 0.498 g of hydrogen tetrachloroaorate hydrate and metal oxide tin acetate, metal catalyst precursors, respectively, were dissolved in 2.5 ml of dimethylformamide, and 0.4 g of polyvinylacetate (Mw: 1,000,000) was dissolved in 2.5 ml of dimethylformamide. Each was stirred and mixed, and electrospinning, thermocompression bonding, and heat treatment were performed as in Example 1.

5A and 5B are SEM photographs of the metal oxide layer of the gas sensor of Example 2. FIG.

Comparing FIG. 5B and FIG. 4C, as the content of the gold catalyst precursor increases in the ratio [Au] / [Sn], the gold catalyst particles contained in the surface or the inside of the tin oxide nanofibers in the form of a flat belt after heat treatment. You can see more distribution. As shown in this embodiment, by controlling the content ratio of the metal catalyst precursor and the metal oxide precursor, it is possible to easily control the content of the metal catalyst contained in the metal oxide nanofiber network obtained through the thermal compression process and the heat treatment process.

[ Example  3] Gold catalyst precursor  Thermocompression of precursor-polyvinylacetate composite fibers comprising a titanium oxide precursor and Post heat treatment  Through the process Au - TiO ₂  Composition Nanofiber  Network manufacturing

0.4 g of polyvinylacetate (Mw: 1,000,000) was dissolved in 2.5 ml of dimethylformamide for about a day, and a polymer solution precursor hydrogen tetrachloroaorate hydrate and a metal oxide precursor titanium propoxide (Ti propoxide: Ti (OCH (CH3) 2) 4)) was mixed with a solution in which 0.122 g and 0.878 g, respectively, were dissolved in 2.5 ml of dimethylformamide (DMF).

The spinning solution was electrospun, thermally compressed and heat treated as in Example 1. SEM images of the results of each step are shown in FIGS. 6A to 6C.

The average diameter of the titanium oxide (TiO ₂ ) nanofibers including the gold catalyst heat-treated at 450 ℃ according to the present invention is 200 ~ 1000nm, the average size of the titanium oxide nanoparticles constituting the nanofiber is 15nm, gold catalyst The average size of the particles is 20 nm.

[ Example  4] thermocompression bonding of precursor-polyvinylacetate composite fibers comprising palladium catalyst precursor and tin oxide precursor; Post heat treatment  Through the process Pd - SnO ₂  Composition Nanofiber  Network manufacturing

A polymer solution in which 0.4 g of polyvinylacetate (Mw: 1,000,000) was dissolved in 2.5 ml of dimethylformamide and dissolved for about a day, and a palladium acetate trimer (Pd (C ₂ H ₃ O) as a metal catalyst precursor: ₂ ) ₂ ] ₃ ) and a solution in which 0.05 g and 0.95 g of tin acetate, a metal oxide precursor, respectively, were dissolved in 2.5 ml of dimethylformamide (DMF).

The spinning solution was electrospun, thermally compressed and heat treated as in Example 1. SEM images of the results of each step are shown in FIGS. 7A to 7C.

Figure 7a shows a SEM photograph of the precursor-polymer composite fiber comprising a palladium catalyst precursor and a tin oxide precursor obtained through electrospinning. FIG. 7B illustrates a structure in which precursor-polymer composite fibers including a palladium catalyst precursor and a tin oxide precursor are melted and connected to each other through a melting process of a polymer (PVAc) occurring in a thermocompression bonding process, and FIG. 7C illustrates a thermocompression bonding process. After the heat treatment at 450 ° C. for 30 minutes, the results show that a continuous flat belt-shaped tin oxide nanofiber network composed of fine nanoparticles is obtained. It can be seen that fine nanometer-sized palladium catalyst particles are uniformly distributed on the surface of the continuous tin oxide nanofiber network.

[ Example  5] thermocompression bonding of precursor-polyvinylacetate composite fibers comprising palladium catalyst precursor and tin oxide precursor; Post heat treatment  Through the process Pd - SnO ₂  Composition Nanofiber  Network manufacturing

0.25 g and 0.75 g of palladium acetate trimer and tin acetate, respectively, were dissolved in 2.5 ml of dimethylformamide, and 0.4 g of polyvinylacetate (Mw: 1,000,000) was dissolved in 2.5 ml of dimethylformamide. Was prepared.

The spinning solution was electrospun, thermally compressed and heat treated as in Example 1.

SEM images of the results of each step are shown in FIGS. 8A to 8C. A scanning electron micrograph of the precursor-polymer composite fiber including the obtained palladium catalyst precursor and tin oxide precursor is shown in FIG. 8A. FIG. 8B shows a structure in which precursor-polymer composite fibers including a palladium catalyst precursor and a tin oxide precursor are connected to each other through the overall melting process of the polymer (PVAc) occurring during the thermal compression process, and after palladium undergoes the thermal compression process It can be confirmed by scanning electron micrographs that they are aggregated together and distributed as ultrafine particles. FIG. 8C shows that a tin oxide nanofiber network in the form of a continuous flat belt consisting of fine nanoparticles is obtained after thermal compression and heat treatment. It can be seen that fine palladium catalyst nanoparticles are evenly distributed on the surface of the continuous tin oxide nanofiber network.

Comparing FIG. 8C and FIG. 7C performed by varying the ratio of [Pd] / [Sn], as the content of the palladium catalyst precursor increases, the palladium catalyst contained in the surface or inside of the tin oxide nanofiber in the form of flat belt after heat treatment It can be seen that there is more distribution of particles. As shown in this embodiment, by controlling the content ratio of the metal catalyst precursor and the metal oxide precursor, it is possible to easily control the content of the metal catalyst contained in the metal oxide nanofiber network obtained through the thermal compression process and the heat treatment process.

[ Example  6] Silver catalyst precursor  Thermocompression bonding of precursor-polyvinylacetate composite fibers comprising tin oxide precursors and Post heat treatment  Through the process Ag - SnO ₂  Composition Nanofiber  Network manufacturing

0.2 g of silver nitrate (AgNO ₃ ) and 0.8 g of tin acetate were dissolved in 2.5 ml of dimethylformamide, and 0.4 g of polyvinylacetate (Mw: 1,000,000) was dissolved in 2.5 ml of dimethylformamide. Each of these was stirred and mixed to prepare a spinning solution. The spinning solution was electrospun, thermally compressed and heat treated as in Example 1.

The sensor using the nanofiber of the present invention is ZnO, VO ₂ , In ₂ O ₃ , NiO, MoO ₃ , SrTiO ₃ , Fe ₂ having the semiconductor properties as well as SnO ₂ and TiO ₂ demonstrated in Examples 1 to 6 Flat belt-shaped nanofibers made of nanoparticles, which are formed on the surface or inside of metal oxides such as O ₃ , WO ₃ , CuO and at least one of Cu, Fe, Pd, Ag, Pt, Ni, Au Any kind of combination may be used, including the network. Various environmental gases (HC, H ₂ , O ₂ , CO, NOx, alcohol, NH ₃ , CH ₄ , SOx, DMMP, phenol, acetone, formaldehyde, VOCs, etc.) using nanofiber network materials containing such catalysts It is possible to manufacture an ultra high sensitivity sensor for detection. In particular, if it is a hazardous substance that can be detected through a change in resistance, it does not limit the specific gas.

Hereinafter, the sensor capability for various gases was tested.

[ Experimental Example  One] Pd - SnO ₂  Composition Nanofiber  Network H ₂  Gas sensor

In Example 5, Au was formed of an alumina (Al ₂ O) formed of an interdigital electrode (finger width: 200 μm, finger spacing: 200 μm, finger length: 8 mm, finger pair: 7). ₃ ) On the substrate, a sensor material is prepared in which fine palladium nanoparticles are evenly distributed on the surface of a SnO ₂ nanofiber network in the form of a continuous flat belt composed of fine nanoparticles. Using this, the change in the resistivity before and after the reaction of the sensor was measured while changing the hydrogen (H ₂ ) concentration and changing the temperature to 200 to 350 ° C. The sensor electrode on which the nanofiber network of Pd-SnO ₂ composition is formed is mounted in a quartz tube in a tube furnace. Pt / Pt-Rh (type S) thermocouples are used to measure changes in temperature while measuring resistance changes to various gas and concentration changes in thin Pd-SnO ₂ nanofiber network layers. The gas flow rate was controlled by MFC (Tylan UFC-1500A mass flow controller and Tylan RO-28 controller). The reaction was reversible and the response time was quite fast. This measurement can be carried out not only in the tube but also in the chamber in which the heating element is mounted.

FIG. 9 is a graph illustrating a result of measuring a change in resistance while changing a concentration from 50 ppb to 1500 ppb for H ₂ gas at 350 ° C. for the gas sensor of Example 5. FIG.

Referring to FIG. 9, the gas sensor of Example 5 shows the characteristics of a typical n-type semiconductor in which the resistance decreases during exposure to reducing gas (H ₂ ). Pd catalyst particles were uniformly coated on the metal oxide of the gas sensor of Example 5, and it was confirmed that gas sensor measurement was well performed even for a very small amount of H ₂ of 50 ppb. In addition, as shown in FIG. 9, the value of I / Io (I = current measured during exposure to a test gas, Io = basic current measured in the atmosphere) is I / Io = when exposed to 1500 ppb of H ₂ based on air concentration. It showed a high value above 3.5. These results demonstrate that the fifth embodiment of the gas sensor, the sensor consisting of a thin layer of the nanofiber network, Pd-SnO ₂ composition that is very promising as a useful gas sensor for the detection of H ₂ ppb level (level).

10 is a graph showing a result of measuring a change in resistance while changing the concentration of the gas sensor of Example 5 with respect to H ₂ gas at 300 ℃ to 50ppb ~ 250ppb.

Referring to FIG. 10, Pd catalyst particles were uniformly coated on the metal oxide of the gas sensor of Example 5, and it was confirmed that gas sensor measurement was well performed even for a very small amount of H ₂ of 50 ppb. In addition, I / Io value showed more than I / Io = 1.6 when exposed to 250ppb H ₂ based on air concentration. This proves that the gas sensor of Example 5 is very promising as a gas sensor useful for detecting ppb levels of H ₂ .

FIG. 11 is a graph showing the change in resistance measured while changing the concentration from 50ppb to 250ppb for H ₂ gas at 200 ° C. using the gas sensor of Example 5. FIG.

Referring to FIG. 11, in spite of the decrease in kinetics due to the low measurement temperature, it can be seen that the change in resistance is clearly observed even at 250 ppb as in FIG. 10. This result shows that when the SnO ₂ nanofiber network structure in which the fine Pd nanoparticles of the present invention are uniformly applied to the gas sensor is used, the sensor having excellent H ₂ detection characteristics can be manufactured even at a low temperature of 200 ° C. .

12 is a graph showing a reaction rate measured at a concentration of 50 ppb for H ₂ gas at 350 ° C. using the gas sensor of Example 5. FIG.

Referring to FIG. 12, it can be seen that excellent saturation of the current change occurs in 10 minutes even at an extremely low concentration of 50 ppb.

FIG. 13 is a graph showing a reaction rate measured at a concentration of 1000 ppb for H ₂ gas at 350 ° C. using the gas sensor of Example 5. FIG.

Referring to FIG. 13, it can be seen that excellent saturation of the current change occurs in 4 minutes even at a low concentration of 1000 ppb. 12 and 13, when the concentration is 1000 ppb or more, a faster response speed can be expected.

[ Experimental Example  2] Pd - SnO ₂  Composition Nanofiber  Network NO ₂  Gas sensor

Using the sensor material of Example 5, while changing the concentration of nitrogen oxides (NO ₂ ) instead of hydrogen (H ₂ ) in the same manner as Experimental Example 1, the change in the specific resistance of the sensor before and after the reaction at 200 ~ 350 ℃ It was.

14 is a graph showing the results of measuring the change in resistance while changing the concentration from 50ppb to 1500ppb for NO ₂ gas at 350 ℃ using the gas sensor of Example 5.

Referring to FIG. 14, the gas sensor of Example 5 shows the characteristics of a typical n-type semiconductor in which the resistance increases during exposure to oxidizing gas (NO ₂ ). Since the Pd catalyst particles are uniformly applied to the flat SnO ₂ nanofiber network structure composed of fine nanoparticles, it can be confirmed that the gas sensor is well measured even for a very small amount of NO ₂ of 50 ppb. In addition, the I / Io value showed a change of I / Io = 0.25 when exposed to 1500ppb of NO ₂ on the basis of atmospheric concentration.

15 is a graph showing a change in resistance measured while changing the concentration from 50ppb to 250ppb for the NO ₂ gas at 300 ° C using the gas sensor of Example 5. FIG.

Referring to FIG. 15, it can be seen that gas sensor measurement is well performed even for a very small amount of NO ₂ of 50 ppb.

16 is a graph showing the change in resistance measured while changing the concentration from 250ppb to 2000ppb for NO ₂ gas at 250 ℃ using the gas sensor of Example 5.

Referring to FIG. 16, gas sensor measurement is well performed even at a low measurement temperature of 250 ° C., and a particularly noticeable change in resistance is observed even at a low NO ₂ of 250 ppb.

17 is a graph showing a change in the resistance measured while changing the concentration from 25ppb to 250ppb for the NO ₂ gas at 200 ℃ using the gas sensor of Example 5.

Referring to FIG. 17, it can be seen that the resistance change is clearly observed even at the 250 ppb level despite the decrease in the kinetic due to the low measurement temperature. This result shows that when a SnO ₂ nanofiber network structure in which fine Pd nanoparticles are uniformly coated is used for a gas sensor, a sensor having excellent NO ₂ detection characteristics can be manufactured even at a low temperature of 200 ° C.

[ Experimental Example  3] Pd - SnO ₂  Composition Nanofiber  Network CO  Gas sensor

Using the sensor material of Example 5, the same as Experimental Example 1, but the change in the specific resistance before and after the reaction at 250 ~ 300 ℃ for CO instead of hydrogen (H ₂ ) was measured.

18 is a graph showing the results of measuring the change in resistance while changing the concentration from 50ppb to 250ppb for CO gas at 300 ℃ using the gas sensor of Example 5.

Referring to FIG. 18, it can be seen that the resistance hardly changes with the change of the CO gas concentration. This result shows that the flat belt SnO ₂ nanofiber network containing Pd catalyst particles has almost no reactivity with CO gas at the level of 50 ppb to 250 ppb.

19 is a graph showing the results of measuring the change in resistance while varying the concentration from 250ppb to 2000ppb for CO gas at 250 ℃ using the gas sensor of Example 5.

Experimental Example 3 is significantly different from the results showing excellent sensor responsiveness to the H ₂ and NOx gas of a very small concentration of 50ppb in Experimental Example 1 and Experimental Example 2. This suggests that the sensor, which consists of a flat belt-shaped SnO ₂ nanofiber network containing Pd catalyst particles, has better selectivity for detecting H ₂ and NO x at ppb level than CO gas. This shows that the gas sensor of the present invention is excellent in selectivity with respect to gas, and thus, when various reaction gases are present at the same time, each of them can be accurately distinguished.

[ Experimental Example  4] Ag - SnO ₂  Composition Nanofiber  Network H ₂  Gas sensor

According to Example 6, Au was formed of an alumina (Al ₂ ) formed of an interdigital electrode (finger width: 200 μm, finger spacing: 200 μm, finger length: 8 mm, finger pair: 7). O ₃₎ in microscopic flat belt in the form of SnO ₂ nanofiber network surface of the continuous phase consisting of fine nano-particles on a substrate will produce a sensor element in which the nanoparticles evenly distributed. The sensor was reacted with various gases and the resistance values before and after the reaction were measured. Experimental conditions are the same as in Experimental Example 1.

20 is a graph showing a result of measuring a change in resistance while changing the concentration from 50ppb to 250ppb for H ₂ gas at 300 ° C using the gas sensor of Example 6. FIG.

The gas sensor of Fig. Referring to 20, Embodiment 6 will see the changes in the resistance hardly for H ₂ concentration of 50ppb ~ 200ppb, also the concentration of H ₂ is when reaches 250ppb, the resistance starts to decrease. Can be. This result shows that the flat belt SnO ₂ nanofiber network containing Ag catalyst particles has a lower sensitivity than the SnO ₂ nanofiber network containing Pd catalyst particles.

21 is a graph showing a result of measuring the change in resistance while changing the concentration from 50ppb to 250ppb for H ₂ gas at 250 ℃ using the gas sensor of Example 6.

Referring to FIG. 21, similar to FIG. 20, there is no response to a change in H ₂ concentration between 50 ppb and 200 ppb, but the current increases at 250 ppb, and the reaction rate is slower at 250 ° C. than at 300 ° C. at 250 ppb. It can be seen.

[ Experimental Example  5] Ag - SnO ₂  Composition Nanofiber  Network NO ₂  Gas sensor

Using the sensor material of Example 6, the same as in Experimental Example 4, but the specific resistance change before and after the reaction was measured at 250 ~ 350 ℃ for NO ₂ instead of hydrogen (H ₂ ).

22 is a graph showing a result of measuring the change in resistance while changing the concentration from 50ppb to 250ppb with respect to NO ₂ gas at 350 ℃ using the gas sensor of Example 6.

Referring to FIG. 22, the gas sensor of Example 6 shows the characteristics of a typical n-type semiconductor in which the resistance increases during exposure to oxidizing gas (NO ₂ ). Even with low NO ₂ concentrations of 50 ppb, a significant change in resistance is observed.

FIG. 23 is a graph showing a result of measuring a change in resistance while changing a concentration from 50 ppb to 250 ppb for a NO ₂ gas at 300 ° C. using the gas sensor of Example 6. FIG.

Referring to FIG. 23, even a low NO ₂ concentration of 50 ppb exhibits excellent characteristics in which a noticeable change in resistance is observed.

24 is a graph showing the results of measuring the change in resistance while changing the concentration from 50ppb to 250ppb for NO ₂ gas at 250 ℃ using the gas sensor of Example 6.

Referring to FIG. 24, even when the NO ₂ concentration of 50 ppb is apparent, a significant change in resistance is observed.

Based on Experimental Example 4 and Experimental Example 5, it can be seen that the gas sensor using the SnO ₂ nanofiber network containing Ag catalyst particles has better selectivity of NO ₂ than H ₂ gas at a concentration of 250 ppb or less. .

[ Experimental Example  6] Ag - SnO ₂  Composition Nanofiber  Network CO  Gas sensor

Using the sensor material of Example 6, but in the same manner as in Experiment 4, the specific resistance change before and after the reaction was measured at 350 ℃ for CO instead of hydrogen (H ₂ ).

25 is a graph showing the results of measuring the change in resistance while changing the concentration from 50ppb to 250ppb for CO gas at 350 ℃ using the gas sensor of Example 6.

Referring to FIG. 25, it can be seen that the resistance hardly changes with the change of the CO gas concentration. Based on Experimental Example 4, Experimental Example 5, and Experimental Example 6, the gas sensor using the SnO ₂ nanofiber network containing Ag catalyst particles is NO ₂ , CO and H ₂ at a concentration of 250 ppb or less. It can be seen that when the gases are mixed together, NO ₂ can be selectively fractionated. This is distinguished from the thin SnO ₂ nanofiber network layer containing Pd catalyst particles showing excellent detection characteristics for H ₂ gas.

[ Comparative example  One] SnO ₂  Composition Nanofiber  Network NO ₂  Gas sensor

In order to compare with the sensor of the present invention prepared by uniformly distributing nanometer-sized metal catalyst on the surface and inside of the metal oxide nanofiber network, a gas sensor using a SnO ₂ nanofiber network containing no metal catalyst was prepared. SnO ₂ nanofiber networks were prepared similarly to the examples described above except that no metal catalyst was added. In other words, a spinning solution in which 6 g of tin oxide precursor (tin acetate) and 2.4 g of polymer (PVAc) were mixed in 30 ml of a solvent (DMF) was used for Au to have an interdigital electrode (finger width: 200 µm, finger spacing: 200 μm, finger length: 8 mm, finger pair (fair): formed on an alumina (Al ₂ O ₃ ) substrate formed by 7), thermocompression bonding (120 ° C., 0.1 MPa, 30 seconds), and heat treatment at 450 ° C. To prepare a sensor.

The characteristics of the sensor were measured by the method described in Experimental Example 1, and the measurement temperature was observed at 310 ° C. while changing the concentration of NO ₂ gas to 0.5 ppm to 50 ppm.

FIG. 26 is a graph illustrating a result of measuring a change in resistance while changing a concentration from 0.5 ppm to 50 ppm with respect to NO ₂ gas at 310 ° C. using the gas sensor of Comparative Example 1. FIG.

Referring to FIG. 26, for a NO ₂ concentration of 1.0 ppm or more, a large resistance change is shown, and as the concentration of NO ₂ is increased, gas sensing characteristics are further increased. However, below 0.5 ppm, due to the low gas concentration, the change of resistance was not well observed. This result shows that there is a big difference in sensitivity compared to the gas sensor of the present invention using a metal oxide nanofiber network containing a catalyst.

[ Comparative example  2] SnO ₂  Composition Nanofiber  Network NO ₂  Gas sensor

The experiment was performed in the same manner as in Comparative Example 1, wherein Au was formed of an interdigital electrode (finger width: 20 μm, finger spacing: 20 μm, finger length: 8 mm, finger pair: 10). Prepared on a (300 nm SiO ₂ ) / SiN _X / Si substrate, the width and spacing of the fingers were reduced compared to Comparative Example 1 to minimize the resistance component according to the electrode spacing, the gas sensor test was performed.

The characteristics of the sensor were measured by the method described in Experimental Example 1, and the measurement temperature was observed at 250 ° C. while varying the concentration of NO ₂ gas to 0.5 ppm to 50 ppm.

FIG. 27 is a graph showing a result of measuring a change in resistance while changing a concentration from 0.5 ppm to 50 ppm with respect to NO ₂ gas at 250 ° C. using the gas sensor of Comparative Example 2. FIG.

Referring to FIG. 27, in FIG. 26, the distance between the fingers is relatively wide at 200 μm, so that the resistance is in the range of MΩ. In FIG. 27, the change in resistance is observed in the range of KΩ as the distance between the fingers is reduced to 20 μm. It became. Due to the small finger spacing, the change of resistance can be observed relatively well even at low temperature of 250 ° C. As the concentration of NO ₂ increases, the gas sensing characteristic increases. However, at low concentrations of 0.5 ppm, the change in resistance is not large. In order to observe this precisely, in the inset figure observed at a log scale in FIG. 27, for a concentration of NO ₂ of 0.5 ppm (500 ppm), the change ratio of resistance (R / Ro) is You can see that it is 1.5. This results in less sensitivity than the SnO ₂ sensor with a uniform metal catalyst.

On the other hand, even in the sensor of the present invention using a metal oxide nanofiber network containing a metal catalyst by further reducing the electrode gap, it is possible to obtain a superior sensitivity characteristics.

The gas sensor of the present invention is not only H ₂ and NO ₂ but also various other environmental gases (HC, CO, O ₂ , NO x, alcohol, NH ₃ , CH ₄ , SO x, DMMP, phenol, acetone, formaldehyde, VOCs, etc.). Ultra-high sensitivity gas reaction can also be expected. This sensor response is possible not only at 350 ° C but also at low temperatures of 200 ° C.

In addition, the gas sensor of the present invention is manufactured by various kinds of metal oxide nanofiber networks having various metal catalysts, thereby providing not only high sensitivity but also excellent selectivity. For example, when at least two sensor substrates are arranged, and a gas sensor is manufactured by spinning a spinning solution having different selectivity for each gas on the at least two sensor substrates, the type of gas to be detected is determined. can do.

In the above, the present invention has been described with reference to the illustrated examples, which are only examples, and the present invention can be carried out in various modifications and other equivalent embodiments that are obvious to those skilled in the art. It should be understood that

Figure 1a is a schematic diagram showing a network of nanofibers comprising metal catalyst particles in accordance with the present invention, consisting of metal oxide nanoparticles.

Figure 1b is a schematic diagram illustrating the increase in the surface depletion layer ratio in the metal oxide nanoparticles increases the reactivity of the metal oxide nanoparticles.

2 is a flowchart illustrating a manufacturing method of a gas sensor according to an exemplary embodiment of the present invention.

3 is a diagram illustrating a step of performing electrospinning.

Figure 4a is a SEM photograph of the composite fiber after the electrospinning of the manufacturing process of Example 1.

Figure 4b is a SEM photograph showing the state that the polymer is melted after thermal compression during the manufacturing process of Example 1.

4C is a SEM photograph showing the metal oxide layer of the gas sensor of Example 1. FIG.

5A is a SEM photograph showing the metal oxide layer of the gas sensor of Example 2. FIG.

FIG. 5B is an enlarged SEM photograph of one region of the metal oxide layer of the gas sensor of Example 2. FIG.

Figure 6a is a SEM photograph of the composite fiber after the electrospinning of the manufacturing process of Example 3.

Figure 6b is a SEM photograph showing the state that the polymer is melted after thermal compression during the manufacturing process of Example 3.

6C is an enlarged SEM photograph of one region of the metal oxide layer of the gas sensor of Example 3. FIG.

Figure 7a is a SEM photograph of the composite fiber after the electrospinning of the manufacturing process of Example 4.

FIG. 7B is a SEM photograph showing a state in which the polymer is melted after thermal compression during the manufacturing process of Example 4. FIG.

7C is an enlarged SEM photograph of one region of the metal oxide layer of the gas sensor of Example 4. FIG.

8A is a SEM photograph of the composite fiber after electrospinning during the manufacturing process of Example 5. FIG.

FIG. 8B is a SEM photograph showing a state in which the polymer is melted after thermocompression bonding in the manufacturing process of Example 5. FIG.

8C is an enlarged SEM photograph of one region of the metal oxide layer of the gas sensor of Example 5. FIG.

9 is a graph showing the H ₂ detection characteristic measured by the gas sensor of Example 5 at 350 ° C.

10 is a graph showing the H ₂ detection characteristic measured by the gas sensor of Example 5 at 300 ° C.

11 is a graph showing the H ₂ detection characteristic measured by the gas sensor of Example 5 at 200 ° C.

12 is a graph showing a reaction rate measured at a concentration of 50 ppb for H ₂ gas at 350 ° C. using the gas sensor of Example 5. FIG.

FIG. 13 is a graph showing a reaction rate measured at a concentration of 1000 ppb for H ₂ gas at 350 ° C. using the gas sensor of Example 5. FIG.

14 is a graph showing the NO ₂ detection characteristic measured at 350 ° C. of the gas sensor of Example 5. FIG.

15 is a graph showing the NO ₂ detection characteristic of the gas sensor of Example 5 measured at 300 ° C.

16 is a graph showing the NO ₂ detection characteristic measured at 250 ° C. of the gas sensor of Example 5. FIG.

17 is a graph showing the NO ₂ detection characteristic measured at 200 ° C. of the gas sensor of Example 5. FIG.

18 is a graph showing the CO detection characteristics measured by the gas sensor of Example 5 at 300 ° C.

19 is a graph showing the CO detection characteristics measured by the gas sensor of Example 5 at 250 ° C.

20 is a graph showing the H ₂ detection characteristics measured by the gas sensor of Example 6 at 300 ° C.

21 is a graph showing the H ₂ detection characteristics measured by the gas sensor of Example 6 at 250 ° C.

22 is a graph showing the NO ₂ detection characteristic of the gas sensor of Example 6 measured at 350 ° C.

FIG. 23 is a graph showing the NO ₂ detection characteristic of the gas sensor of Example 6 measured at 300 ° C. FIG.

24 is a graph showing the NO ₂ detection characteristic of the gas sensor of Example 6 measured at 250 ° C.

25 is a graph showing the CO detection characteristics measured by the gas sensor of Example 6 at 350 ° C.

FIG. 26 is a graph showing NO ₂ detection characteristics measured by the gas sensor of Comparative Example 1 at 310 ° C. FIG.

27 is a graph showing the NO ₂ detection characteristic of the gas sensor of Comparative Example 2 measured at 250 ° C.

Claims (17)

It comprises a sensor substrate and a sensor material formed on the pressing surface of the sensor substrate, The sensor material is a gas sensor, characterized in that it comprises a metal catalyst particles, a porous thin layer having a network structure of nano-fiber (Nano-fiber) comprising a nanoparticle of a metal oxide. The gas sensor according to claim 1, wherein the metal catalyst particles are distributed on the surface and inside of a network structure of nano-fibers including nanoparticles of metal oxides. The gas sensor according to claim 1, wherein the network structure of the nanofibers including the nanoparticles of the metal oxide is in the form of a flat belt. The gas sensor according to claim 1, wherein the average diameter of the metal catalyst particles is 1 to 100 nm, the average diameter of the nanoparticles is 1 to 100 nm, and the average diameter of the nanofibers is 50 to 3000 nm. . The gas sensor of claim 1, wherein the metal oxide nanoparticles have a grain shape or a rod shape. The method of claim 1, wherein the metal catalyst particles are selected from the group consisting of copper (Cu), iron (Fe), palladium (Pd), silver (Ag), platinum (Pt), nickel (Ni) and gold (Au). Gas sensor, characterized in that one or two or more. The metal oxide of claim 1, wherein the metal oxide is SnO ₂ , TiO ₂ , ZnO, VO ₂ , In ₂ O ₃ , NiO, MoO ₃ , SrTiO ₃ , Fe ₂ O ₃ , WO _3, and CuO. Or two or more kinds of gas sensors. The method of claim 1, wherein the sensor substrate is platinum (Pt), gold (Au), palladium (Pd), iridium (Ir), silver (Ag), ruthenium (Ru), nickel (Ni), stainless steel (STS), Group consisting of aluminum (Al), molybdenum (Mo), chromium (Cr), copper (Cu), titanium (Ti), tungsten (W), ITO (In doped SnO ₂ ) and FTO (F doped SnO ₂ ) It is selected from the group consisting of a ceramic substrate, an alumina (Al ₂ O ₃ ) substrate, a silicon (Si) substrate and an silicon oxide (SiO ₂ ) substrate on which an insulating layer is deposited. Gas sensor. The gas sensor according to claim 1, wherein at least two sensor substrates are arranged, and different sensor materials are formed on the at least two sensor substrates. Spinning a solution containing a metal catalyst precursor, a metal oxide precursor, a polymer, and a solvent on the sensor substrate to form a composite fiber; Compressing the composite fiber on the sensor electrode by thermocompression or thermocompression; And And heat-treating the compressed composite fiber to remove the polymer from the composite fiber. The method of claim 10, wherein the metal catalyst precursor is selected from the group consisting of copper (Cu), iron (Fe), palladium (Pd), silver (Ag), platinum (Pt), nickel (Ni) and gold (Au) ions. Method for producing a gas sensor, characterized in that the precursor comprising one or two or more. The method of claim 10, wherein the metal oxide precursor is tin (Sn), titanium (Ti), zinc (Zn), vanadium (V), indium (In), nickel (Ni), molybdenum (Mo), strontium (Sr), One or two or more selected from the group consisting of iron (Fe), tungsten (W), copper (Cu), calcium (Ca), niobium (Nb), cobalt (Co), and gallium (Ga) ions Method for producing a gas sensor comprising a precursor comprising. The method of claim 10, wherein the polymer is polyurethane, polyetherurethane, polyurethane copolymer, cellulose acetate, cellulose acetate butylate, cellulose acetate propionate, polymethylmethacrylate (PMMA), polymethylacrylate (PMA). , Polyacryl copolymer, polyvinylacetate (PVAc), polyvinylacetate copolymer, polyvinyl alcohol (PVA), polyperfuryl alcohol (PPFA), polystyrene, polystyrene copolymer, polyethylene oxide (PEO), polypropylene oxide ( PPO), polyethylene oxide copolymer, polypropylene oxide copolymer, polycarbonate (PC), polyvinyl chloride (PVC), polycaprolactone, polyvinylpyrrolidone (PVP), polyvinyl fluoride, polyvinylidene paste One or two or more selected from the group consisting of a fluoride copolymer and a polyamide Method of producing a gas sensor as ranging. The method of claim 10, wherein the solvent is one selected from the group consisting of dimethylformamide (DMF), acetone, detrahydrofuran, toluene, water, and mixtures thereof. The method of claim 10, wherein the spinning is in the group consisting of electrospinning method, melt-blown method, flash spinning method and electrostatic melt-blown method Method for producing a gas sensor, characterized in that using one selected. The method of claim 10, wherein the thermocompression is a step of melting the polymer partially or entirely of the nanofiber by applying a pressure at a temperature equal to or higher than the glass transition temperature of the polymer. The method of claim 10, wherein the thermal pressurization, inducing the melting of the polymer through a heating process at a temperature above the glass transition temperature of the polymer, or pressurized using a compressed air having a temperature above the glass transition temperature of the polymer to Method of producing a gas sensor, characterized in that the step of inducing melting.

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