KR102092452B1 - Gas sensor and mebber using metal oxide nanofibers including nanoscale catalysts and multichannel, and manufacturing method thereof - Google Patents

Abstract

 Embodiments according to the present invention relates to a member for a gas sensor, a gas sensor using the same, and a method for manufacturing the same, and specifically, nanoparticle catalyst is used for a nanoparticle catalyst inside the nanofiber by using apoferritin containing the nanoparticle catalyst in an internal hollow structure. The present invention relates to a member for a gas sensor, a gas sensor, and a manufacturing method using a multi-channel metal oxide nanofiber material functionalized by being uniformly attached to a multi-channel and an external surface.

Description

Gas sensor member and its manufacturing method using metal oxide nanofibers containing nanoparticle catalyst and multi-channel pores {GAS SENSOR AND MEBBER USING METAL OXIDE NANOFIBERS INCLUDING NANOSCALE CATALYSTS AND MULTICHANNEL, AND MANUFACTURING METHOD THEREOF}

Embodiments of the present invention relates to a member for a gas sensor using a nanoparticle catalyst and a metal oxide nanofiber containing multi-channel pores, a gas sensor, and a method for manufacturing the same, specifically, phase separation of two polymers that are not mixed with each other By combining phenomenon and electrospinning, multi-channel pores are formed inside the nanofiber, and the animal protein apoferritin is used as a binding means for the nanoparticle catalyst, so that the nanoparticle catalyst is used for the internal multichannel and external surface of the nanofiber. It relates to a multi-channel metal oxide nanofibers functionalized by being uniformly bonded to the gas sensor and a method for manufacturing the multichannel metal oxide nanofibers using the multi-channel metal oxide nanofiber as a member for a gas sensor.

Metal oxide semiconductor-based resistance change type gas sensors have attracted great attention for reasons of simple manufacturing method, portability, and high sensitivity. Attempts to commercialize the metal oxide semiconductor-based resistance change type gas sensor in various fields such as observation of air pollution sources, alcohol breathalyzers, gas detectors for sick house syndrome, and diagnosis of diseases are taking place. In particular, as health care becomes more and more important, exhalation analysis gas sensor technology, which can be used for early diagnosis and daily diagnosis of diseases, has attracted great attention. In a person's exhalation, biomarker gas indicating a specific disease is included. In a person's exhalation, a specific biomarker gas is present 2-10 times more than a healthy person. For example, diabetics have 2-6 times more acetone gas in their exhalation than healthy people. Therefore, if a specific biomarker gas contained in a person's exhalation can be selectively detected using a gas sensor, a specific disease can be diagnosed early. However, since human exhalation is very high and includes hundreds of gas mixtures, it is required to develop a highly sensitive and highly selective sensor capable of selectively detecting a specific biomarker gas even in a humid atmosphere. In addition, since biomarker gases in exhalation are released at very low concentrations ranging from 10 parts per billion (ppb) to 10 parts per million (ppm), it is necessary to study a sensing material capable of selectively detecting trace amounts of gas. Do.

The metal oxide semiconductor-based resistance change type gas sensor detects a specific gas by measuring the change in electrical resistance according to the adsorption and desorption reactions of the gas generated on the surface of the sensing material. Therefore, in order to increase the sensitivity of the gas sensor, it is necessary to increase the surface area of the sensing material to increase the surface reaction of the sensing material and the specific gas. In addition, the sensing material of the hollow structure promotes the diffusion of gas not only to the outside but also to the inside of the sensing material, so that the sensing material can react more effectively with the gas. In addition, a catalyst can be bound to the surface of the sensing material, thereby enhancing selective surface reaction. Catalysts used in metal oxides for gas sensors typically include chemical sensitizers such as platinum (Pt) and gold (Au), and electronic sensitizers such as palladium (Pd) and nickel (Ni). have. These catalysts enhance the selective surface reaction of the sensing material and the target gas, and promote the adsorption and desorption reactions of the gas, thereby greatly improving the sensing characteristics of the gas sensor.

In order to meet the above-described strategies for increasing the characteristics of the gas sensor, it is essential to utilize a nanomaterial functionalized with a catalyst. Nanomaterials are expected to effectively increase the reaction of gases due to the large surface area. Accordingly, studies using various nano structures such as nanoparticles, nanofibers, and nanosheets as sensing materials for gas sensors are actively being conducted. In particular, nanofibers have a large aspect ratio, one-dimensional structure, and are promoted as a sensing material for gas sensors because they promote diffusion of gas through a number of pores formed by entanglement between nanofibers. Among these methods of synthesizing nanofibers, electrospinning is a very simple process and a variety of applications. In particular, electrospinning can very easily synthesize one-dimensional nanofibers with a catalyst bound by mixing catalyst particles in a solution. Because of these advantages, studies using nanofibers synthesized through electrospinning as sensing materials for gas sensors are actively being conducted.

Despite such numerous research results, gas sensors for disease diagnosis have not been commercialized. In order to commercialize a gas sensor that can diagnose diseases through exhalation analysis, in fact, high-sensitivity characteristics capable of detecting 10 ppb to 10 ppm levels of gas, fast reaction speed within a few seconds for use as a real-time analysis device, and only specific gases are selected Both the ability to detect and stability that does not decrease the reaction force after hundreds of reactions must be secured. In order to satisfy the above-mentioned factors, it is necessary to not only uniformly bind the nano-sized catalyst to the sensing material, but also to create a synergistic effect between the catalyst and the nanostructure through shape control of the sensing material. That is, it is necessary to study the structure that can maximize the effect of the catalyst.

Embodiments according to the present invention, including the nanoparticle catalyst of the size of 1-5 nm in the inner hollow of the animal protein apoferritin (apoferritin), by combining the phase separation and electrospinning of two polymers that are not mixed with each other , A plurality of second polymer fibers occupying a discontinuous phase inside the first polymer fiber occupying the continuous phase of the nanofibers, and composite nanofibers in which apoferritin containing nanoparticle catalysts in the inner hollow is uniformly contained inside and on the surface Is synthesized, and then, through the high-temperature heat treatment, the second polymer fibers are decomposed, multi-channel pores are formed inside the nanofibers, apoperitin is decomposed, and nanoparticle catalysts are uniformly bound to the inner multi-channels and the outer surface of the nanofibers. It provides a method for synthesizing functionalized sensing substances.

In particular, the formation of multi-channels not only increases the sensitivity by increasing the gas reaction through an increase in the specific surface area, but also provides an efficient gas reaction through a structure in which the gas can diffuse into the interior of the nanofibers. Since the catalyst bound to the inside is also functionalized, the sensing characteristics are significantly increased. In addition, during the high temperature heat treatment process of the nanofibers, as the thermal decomposition of the second polymer occupying the discontinuous phase occurs at a temperature higher than the crystallization of the metal oxide precursor, the heat transferred to the metal oxide particles is reduced, and a number of second polymer fibers The growth of metal oxide particles is suppressed according to the support inside the nanofibers, thereby forming a metal oxide having a small particle size. This small particle size maximizes the resistance change depending on the presence or absence of gas, resulting in high-sensitivity characteristics that can detect even trace amounts of gas. In the present invention, the nanoparticle catalyst is functionalized by being uniformly bound to the inner multichannel and the outer side of the nanofiber, and proposes a multichannel metal oxide nanofiber sensing material synthesis technology and a gas sensor technology using the same. .

The metal oxide precursor is oxidized and crystallized by heat treatment on a composite nanofiber comprising apoferritin containing a nanoparticle catalyst in an interior hollow, two polymers that are not mixed with each other, and a metal oxide precursor to form metal oxide nanofibers, , As the multi-channel by phase separation of the two polymers is formed inside the metal oxide nanofiber, and the apoferrin is removed by the heat treatment, the inside of each of the multi-channel and the metal oxide nanofiber outer surface It provides a multi-channel metal oxide nanofibers, characterized in that the nanoparticle catalyst is bound and functionalized.

According to one side, the composite nanofibers include a first polymer fiber in which the metal oxide precursor is mixed while occupying a continuous phase of the nanofibers by phase separation of the two polymers, and inside the first polymer fiber. It may further include a plurality of second polymer fibers occupying the discontinuous phase, and further include the apoferritin on the surface and inside.

According to another aspect, through the heat treatment, the metal oxide precursor forms a multi-channel form formed inside the nanofiber by removing the second polymer fiber in the process of thermally decomposing the first polymer fiber and the second polymer fiber. It is oxidized and crystallized and maintained as a metal oxide, and the apoferritine is thermally decomposed to form pores in the nanofibers, and at the same time, the nanoparticle catalyst contained in the apoferritin's hollow interior is bound to the surface of the nanofiber and each of the multichannel It can be characterized by being.

According to another aspect, in the process of heat treatment for the composite nanofibers, as the thermal decomposition of a plurality of second polymer fibers occupying a discontinuous phase occurs at a relatively higher temperature than crystallization of the metal oxide precursor, the metal oxide particles It may be characterized in that the heat transferred is reduced, thereby limiting the size of the metal oxide particles.

According to another aspect, the thermal decomposition of the second polymer fiber may be characterized in that it occurs at a temperature relatively higher than the temperature included in the range of 50-150 ° C than the crystallization of the metal oxide precursor.

According to another aspect, the size of the metal oxide particles forming the metal oxide nanofibers may be characterized in that included in the range of 1 to 20 nm.

According to another aspect, the two polymers are polyvinylpyrrolidone, poly (styreneacrylonitrile), polystyrene, cellulose acetate, poly ( It is composed of a combination of a first polymer selected from ethylene oxide), poly (methylmethacrylate), and a second polymer including polyacrylonitrile. It can be characterized as.

According to another aspect, the weight ratio of the second polymer occupying the discontinuous phase in the composite nanofiber to the weight of the first polymer occupying the continuous phase in the composite nanofiber may be characterized in that it is included in the range of 50 to 150%. You can.

According to another aspect, the number of the multi-channels may be included in the range of 5 to 20 per one of the composite nanofibers, and the diameter of individual channels may be included in the range of 10 to 50 nm.

According to another aspect, the apoferritine is a structure having a hollow inside, encapsulating one or more catalytic metal ions into the inner hollow, and the diameter of the nanoparticle catalyst generated by reduction of the catalytic metal ion is 1 to 1 It may be characterized by being included in the range of 5 nm.

According to another aspect, the weight ratio of the nanoparticle catalyst may be characterized in that it is included in a concentration range of 0.01 to 1 wt% compared to the multi-channel metal oxide nanofiber.

According to another aspect, the nanoparticle catalyst is platinum (IV) chloride, platinum (II) acetate, gold (I, III) chloride, gold (III) acetate, silver chloride, silver acetate, Iron (III) chloride, Iron (III) acetate, Nickel (II) chloride, Nickel (II) acetate, Ruthenium (III) chloride, RutheniumAcetate, Iridium (III) chloride, Iridium acetate, Tantalum (V) chloride, Palladium (II) chloride, Lanthanum (III) It may be characterized by being formed by catalytic metal ions synthesized, including at least one metal salt selected from acetate, Copper (II) sulfate and Rhodium (III) chloride.

According to another aspect, the nanoparticle catalyst, Pt, Au, Ag, Fe, Ni, Ru, Ir, Ta, Pd, La, Cu, as the catalytic metal ion contained in the hollow inside of the apoferritin is reduced At least one nanoparticle catalyst selected from Rh, Co, Cr, Zn, W, Sn, Sr, In, Pb, V, Sb, Sc, Ti, Mn, Ga and Ge, included in the interior hollow of the apoferritin, The nanoparticle catalyst contained inside the hollow structure of apoferritin is Pt, PtO, PtO ₂ , Au, Ag, Fe ₂ O ₃ , NiO, RuO ₂ , IrO ₂ , Ta ₂ O ₅ , PdO, PdO ₂ , after heat treatment CuO, Rh ₂ O ₃ , Co ₃ O ₄ , Cr ₂ O ₃ , ZnO, WO ₃ , SnO ₂ , SrO, In ₂ O ₃ , PbO, V ₂ O ₅ , VO ₂ , VO, Sb ₂ O ₃ , Sc ₂ O ₃ , TiO ₂ , MnO ₂ , Ga ₂ O ₃ And may be characterized by being substituted with at least one nanoparticle catalyst of GeO ₂ and bound to the outer surface of the metal oxide nanofiber.

Provided is a gas sensor comprising a sensing material formed by coating multi-channel metal oxide nanofibers on a sensor electrode capable of measuring a change in resistance according to one of the above-described embodiments.

A method for manufacturing a multi-channel metal oxide nanofiber, comprising: (a) synthesizing a nanoparticle catalyst inside a hollow structure of apoferritin; (b) synthesizing an electrospinning solution by dissolving two polymers that are not mixed with each other in a solvent together with a metal oxide precursor; (c) Composite electrospinning comprising apoferritin containing the synthesized nanoparticle catalyst in the synthesized electrospinning solution, and apoferritin containing the nanoparticle catalyst, a metal oxide precursor, and two polymers that are not mixed with each other. Preparing a solution; (d) electrospinning the composite electrospinning solution to produce a composite nanofiber in which apoferritin containing a nanoparticle catalyst is bound to the surface and inside of a metal oxide precursor and a polymer composite nanofiber; And (e) heat-treating the composite nanofibers so that the nanoparticle catalyst is uniformly bound to the inner multichannel and outer surfaces of the multichannel metal oxide nanofibers to produce functionalized multichannel metal oxide nanofibers. It provides a method for manufacturing a multi-channel metal oxide nanofiber.

According to one side, in the step (a), in order to embed the nanoparticle catalyst in the inner hollow of the apoferritin, the catalyst metal salt is added to the solution in which the apoferritin is dissolved to embed a catalyst metal ion, and a reducing agent is added. By reducing the catalytic metal ion to the catalytic metal particles.

According to another aspect, in the step (a), a reducing agent for reducing catalytic metal ions embedded in the hollow of the apoferritin, sodium borohydride (NaBH ₄ ), lithium aluminum hydride (LiAlH ₄ ), nascent (atomic) hydrogen , zinc-mercury amalgam (Zn (Hg)), oxalic acid (C ₂ H ₂ O ₄ ), formic acid (HCOOH), ascorbic acid (C ₆ H ₈ O ₆ ), sodium amalgam, diborane and iron (II) sulfate It may be characterized in that it comprises at least one of.

According to another aspect, in the step (e), in the process in which the two polymers are thermally decomposed and removed through the heat treatment, the second polymer occupying the discontinuous phase is decomposed to form a multi-channel, , The continuous polymer, the first polymer is decomposed, the metal oxide precursor mixed with the first polymer is oxidized and crystallized while maintaining the formed multi-channel form, the apoferritin is decomposed and the nanoparticle catalyst contained in the hollow It may be characterized in that it is bound to the table of the inner and nanofibers of the formed multi-channel.

According to another aspect, in the step (e), the apoferritin is an animal protein having a hollow structure, and pores having a size included in the range of 1 to 15 nm in nanofibers as the protein shell is decomposed during the heat treatment process. It may be characterized by forming.

According to another aspect, the method of manufacturing the multi-channel metal oxide nanofibers, (f) pulverizing and dispersing the multi-channel metal oxide nanofibers in a solvent, spin coating and drop coating on a sensor electrode for a resistance change type gas sensor. And it may be characterized in that it further comprises the step of coating using at least one coating process of the inkjet printing.

According to the present invention, when synthesizing multi-channel metal oxide nanofibers in which a nano-sized catalyst is bound by using a phase separation phenomenon of apoferritin containing a nanoparticle catalyst and two polymers that are not mixed with each other, the nanoparticle catalyst Provides an electronic or chemical sensitization effect, the specific surface area is increased through the multi-channel nanofiber structure, and the area where the gas reacts increases, and the gas can easily penetrate into the channel, so that the gas can penetrate the inside and outside of the nanofiber. It provides all reaction efficiency, and the catalyst existing inside the nanofiber is functionalized through the channel, so that the effect of the catalyst is maximized, it is possible to manufacture a multi-channel metal oxide nanofiber sensing material with excellent sensitivity and selective sensing ability. have. In addition, during the high temperature heat treatment process of the nanofibers, as the thermal decomposition of the second polymer occupying the discontinuous phase occurs at a temperature higher than the crystallization of the metal oxide precursor, the heat transferred to the metal oxide particles is reduced, and a number of second polymer fibers The growth of metal oxide particles is suppressed according to the support inside the nanofibers, thereby forming a metal oxide having a small particle size. This small particle size maximizes the resistance change depending on the presence or absence of gas, resulting in high-sensitivity characteristics that can detect even trace amounts of gas. In addition, since the nano-sized catalyst is embedded in the hollow structure of apoferritin and because these nanoparticle catalysts are uniformly bound to the surface of the metal oxide nanofibers due to the excellent dispersibility of apoferritin, aggregation between the catalyst particles even at a high driving temperature Since it does not occur, it is possible to expect a very good catalytic effect, and has the effect of disclosing a member for a gas sensor, a gas sensor, and a method for manufacturing the gas having selective sensing ability, stability, and excellent sensing characteristics.

The accompanying drawings included as part of the detailed description to aid understanding of the present invention provide embodiments of the present invention, and describe the technical spirit of the present invention together with the detailed description.
1 is a schematic diagram of a member for a multi-channel metal oxide nanofiber gas sensor in which a nano-sized catalyst according to an embodiment of the present invention is functionalized by being uniformly bound to an inner multi-channel and outer surface of a nano-fiber.
Figure 2 is a flow chart of a method for manufacturing a gas sensor using a multi-channel metal oxide nanofiber structure functionalized with nano-sized catalysts uniformly bound to the inner multi-channel and outer surfaces of the nano-fibers according to an embodiment of the present invention.
Figure 3 shows the manufacturing process of the multi-channel metal oxide nanofiber structure functionalized by the nano-sized catalyst uniformly bound to the inner multi-channel and outer surfaces of the nanofibers through an electrospinning method and a heat treatment process according to an embodiment of the present invention. It is a picture showing.
FIG. 4 is a transmission electron micrograph of apoferritin containing Pt nanoparticle catalyst according to Example 1 of the present invention.
Figure 5 is a composite containing apoferritin, polyvinylpyrrolidone, polyacrylonitrile, polyacrylonitrile, tin oxide precursor containing a Pt nanoparticle catalyst synthesized after electrospinning according to Example 2 of the present invention It is a scanning electron microscope photograph of nanofibers.
6 is a scanning electron microscope photograph of multi-channel SnO ₂ nanofibers in which Pt nanoparticles synthesized after high-temperature heat treatment according to Example 2 of the present invention are uniformly bonded to the inner multichannels and outer surfaces of nanofibers.
FIG. 7 is a transmission electron micrograph and component analysis photograph of multichannel SnO ₂ nanofibers in which Pt nanoparticles synthesized after heat treatment according to Example 2 of the present invention are uniformly bonded to the inner multichannel and outer surfaces of nanofibers.
8 is a scanning electron microscope photograph of the SnO ₂ nanofibers in which the Pt nanoparticle catalyst prepared through Comparative Example 1 of the present invention is bound.
9 is a scanning electron microscope photograph of SnO ₂ nanofibers in which the Pt nanoparticle catalyst prepared through Comparative Example 3 of the present invention is not bound.
10 is an Experimental Example 1 of the present invention, according to Comparative Examples 3 and 2, to form a multi-channel SnO ₂ nanofibers in which Pt nanoparticle catalyst is bound and SnO ₂ nanofibers in which Pt nanoparticle catalyst is not bound In the process, polyvinylpyrrolidone, a composite of nanofibers of tin oxide precursors and apoferritin containing Pt nanoparticle catalyst, polyvinylpyrrolidone, polyacrylonitrile, and tin oxide precursors It is a graph showing the change in mass and the degree of heat transfer according to the heat treatment of the composite nanofiber.
Figure 11 is an experimental example 2 of the present invention, Example 2 and Comparative Examples 1 and 2, the binder multichannel Pt nanoparticle catalysts according to 3 SnO ₂ nanofibers, Pt nanoparticle catalyst binder of SnO ₂ nanofibers, This is a graph of reactivity to acetone gas (0.4-5 ppm) at 400 ° C. of a multi-channel SnO ₂ nanofiber without a Pt nanoparticle catalyst and a SnO ₂ nanofiber-based gas sensor without a Pt nanoparticle catalyst.
Figure 12 is an experimental example 2 of the present invention, Example 2 and Comparative Examples 1 and 2, the binder multichannel Pt nanoparticle catalysts according to 3 SnO ₂ nanofibers, Pt nanoparticle catalyst binder of SnO ₂ nanofibers, When the concentration of acetone is 1, 2, 3, 4, 5 ppm at 400 ℃ of multi-channel SnO ₂ nanofibers without Pt nanoparticle catalyst and SnO ₂ nanofibers-based gas sensor without Pt nanoparticle catalyst This is the result of evaluating the characteristics of the reaction rate of the gas sensor.
13 is Experimental Example 2 of the present invention, Pt nanoparticle catalyst according to Example 2 is a multi-channel SnO ₂ nanofiber-based gas sensor at 400 ℃ 1 ppm of gas (acetone, hydrogen sulfide, toluene, ethanol, Sensitivity characteristics to methane, carbon monoxide, formaldehyde, and ammonia).
14 shows Experimental Example 2 of the present invention, and it is a result of repeated sensitivity measurement of 1 ppm acetone gas at 400 ° C. of a multi-channel SnO ₂ nanofiber-based gas sensor in which the Pt nanoparticle catalyst according to Example 2 is bound.

The present invention can be applied to various transformations and can have various embodiments. Hereinafter, specific embodiments will be described in detail with reference to the accompanying drawings.

In the description of the present invention, when it is determined that a detailed description of known technologies related to the present invention may obscure the subject matter of the present invention, the detailed description will be omitted.

Terms such as first and second may be used to describe various components, but the components are not limited by the terms, and the terms are for the purpose of distinguishing one component from other components only. Is used.

Hereinafter, a gas sensor member, a gas sensor using multi-channel metal oxide nanofibers functionalized with nanoparticle catalysts embedded in the hollow structure of apoferritin uniformly bonded to the inner multichannel and outer surfaces of multichannel metal oxide nanofibers, and The manufacturing method will be described in detail with reference to the accompanying drawings.

In one embodiment of the present invention, apoferritin / catalyst is synthesized, and the nanoparticle catalysts are uniformly bound to the inner multichannel and outer surfaces of the nanofibers. Provided is a method for manufacturing a sensing material including an effect and a member for a gas sensor using the same.

A method of manufacturing a sensing material and a member for a gas sensor using the sensing material according to the present embodiment includes (a) embedding a nanoparticle catalyst inside a hollow structure of apoferritin; (b) synthesizing an electrospinning solution by dissolving two polymers and metal oxide precursors that are not mixed with each other in a solvent; (c) preparing a composite electrospinning solution composed of two polymers, apoperitin / metal oxide precursor / incorporating nanoparticle catalyst, by mixing apoperitin with nanoparticle catalyst in an electrospinning solution; (d) electrospinning the composite electrospinning solution to produce a composite nanofiber in which apoferritin containing a nanoparticle catalyst is uniformly contained on the surface and inside of a metal oxide precursor / two polymer composite nanofibers; (e) Through high-temperature heat treatment, the polymer is thermally decomposed to form multiple channels inside the nanofibers, the metal oxide precursor is oxidized and crystallized, and apoferritine is thermally decomposed, so that the nanoparticle catalyst is multi-channel metal oxide nanofibers. Preparing a functionalized multi-channel metal oxide nanofiber uniformly bound to the channel and the outer surface; (f) At least one coating process of spin coating, drop coating, inkjet printing, and dispensing on the sensor electrode for resistance-changing gas sensor by pulverizing and dispersing the nano-channel catalyst-bonded multi-channel metal oxide nanofiber in a solvent. It may include the step of coating using.

At this time, in the step (a), apoferritin is an animal protein having an internal hollow having a size of 8 nm, and one or more catalytic metal ions may be embedded in the internal hollow, and through a reduction process, a diameter of 1-5 nm It forms nanoparticles with a range. In order to embed the catalytic metal ions into the inner hollow of apoferritin, a catalytic metal ion is embedded in a solution in which apoferritin is dissolved, and a reducing agent is added to reduce the catalytic metal ion to catalytic metal particles. Representative metal salts used to embed catalytic metal ions in the interior hollow of apoferritin, platinum (IV) chloride, platinum (II) acetate, gold (I, III) chloride, gold (III) acetate, silver chloride, silver acetate, Iron (III) chloride, Iron (III) acetate, Nickel (II) chloride, Nickel (II) acetate, Ruthenium (III) chloride, RutheniumAcetate, Iridium (III) chloride, Iridium acetate, Tantalum (V) chloride, Palladium (II) chloride, Lanthanum (III) acetate, Copper (II) sulfate, and Rhodium (III) chloride, etc., and using these metal salts, the embedded metal ions undergo a reduction process, Pt, Au, Ag, Fe, Ni , Ru, Ir, Ta, Pd, La, Cu, Rh, Co, Cr, Zn, W, Sn, Sr, In, Pb, V, Sb, Sc, Ti, Mn, Ga and Ge. Reducing agents for reducing metal ions include sodium borohydride (NaBH ₄ ), lithium aluminum hydride (LiAlH ₄ ), nascent (atomic) hydrogen, zinc-mercury amalgam (Zn (Hg)), oxalic acid (C ₂ H ₂ O ₄ ), formic acid (HCOOH), ascorbic acid (C ₆ H ₈ O ₆ ), sodium amalgam, diborane and iron (II) sulfate. The final synthesized, nanoparticle catalyst-embedded apoferritin is prepared by centrifugation and washing, followed by dispersion in a solvent.

In addition, the step (b) is a step of dissolving the metal oxide precursor and two polymers that are not mixed with each other in one solvent. Typical metal oxide precursors include metal-containing acetate, nitrate, chloride, acetylacetonate, methoxide, ethoxide, butoxide, There are isopropoxide and sulfide, and two polymers that do not mix with each other are typically polyvinylpyrolidone and polyacrylonitrile, poly (styreneacrylonitrile) and polyacrylonitrile, cellulose acetate and polyacrylonitrile, poly (methylmethacrylate) and polyacrylonitrile , polystyrene and polyacrylonitrile, and poly (ethylene oxide) and polyacrylonitrile. These two polymers can be dissolved in the same solvent, but cannot be mixed with each other, so that phase separation occurs with the first polymer occupying the continuous phase in the solvent and the second polymer occupying the discontinuous phase. The weight ratio of the second polymer can be variously adjusted in the range of 50-150% of the weight of the first polymer.

In addition, in the step (c), the apoferritin containing the nanoparticle catalyst synthesized in the step (a) is mixed with the electrospinning solution synthesized in the step (b), and the apoferritin containing the nanoparticle catalyst / This is a step of preparing a complex electrospinning solution composed of a metal oxide precursor / two polymers. In the state in which the solution synthesized in step (b) is agitated, a solution in which apoferritine containing a nanoparticle catalyst is dispersed is slowly added to prepare a composite electrospinning solution. When preparing the electrospinning solution, the concentration of apoferritin in which the nanoparticle catalyst is embedded may be variously adjusted in the range of 0.01-1 wt% compared to the metal oxide.

In addition, in step (d), the composite electrospinning solution synthesized in step (c) is electrospinned to synthesize a nanoparticle catalyst-embedded apoferritin / metal oxide precursor / composite nanofiber composed of two polymers. It is a step. During the process of electrospinning the nanofibers, due to the phase separation phenomenon of two polymers that are not mixed with each other, a large number of second polymer fibers occupying a discontinuous phase exist inside the first polymer fibers occupying the continuous phase of the nanofibers, The metal oxide precursor is present with the first polymer that can be mixed, and because of the excellent dispersibility of apoferritin with a nanoparticle catalyst embedded therein, the apoferritin / catalyst is uniformly distributed inside and on the surface of the composite nanofiber. Have

In addition, in the step (e), the second polymer occupying the discontinuous phase is decomposed through the high-temperature heat treatment at 500-700 ° C. of the composite nanofiber synthesized in the step (d), leaving multiple channels inside the nanofiber. , Multi-channel metal oxide nanofibers in which the metal oxide precursor is oxidized and crystallized while maintaining a multi-channel form, and the apoferritine is decomposed to include nanoparticle catalysts included in the inner hollow and uniformly bound to the multi-channel and outer surfaces of the nanofibers Synthesizes. In this heat treatment process, since the temperature at which the second polymer is thermally decomposed is higher than the crystallization temperature of the metal oxide precursor by 50-150 ° C., heat transferred to the metal oxide particles is reduced, and a number of second polymer fibers are formed of nanofibers. The growth of metal oxide particles is suppressed according to the support from the inside, thereby forming a metal oxide having a small particle size of 1 to 20 nm. In addition, the apoferritin is an animal protein composed of an outer diameter of 12 nm and an inner diameter of 8 nm, and is characterized by leaving micropores having a size range of 1 to 15 nm in nanofibers as the protein shell decomposes during the heat treatment process. In addition, the nanoparticle catalyst contained in the hollow structure of apoferritin is Pt, PtO, PtO ₂ , Au, Ag, Fe ₂ O ₃ , NiO, RuO ₂ , IrO ₂ , Ta ₂ O ₅ , PdO, PdO ₂ after heat treatment , CuO, Rh ₂ O ₃ , Co ₃ O ₄ , Cr ₂ O ₃ , ZnO, WO ₃ , SnO ₂ , SrO, In ₂ O ₃ , PbO, V ₂ O ₅ , VO ₂ , VO, Sb ₂ O ₃ , It may be substituted with at least one nanoparticle catalyst of Sc ₂ O ₃ , TiO ₂ , MnO ₂ , Ga ₂ O ₃ and GeO ₂ . In addition, the metal oxide nanofiber formed at this time is ZnO, SnO ₂ , WO ₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , NiO, TiO ₂ , CuO, In ₂ O ₃ , Zn ₂ SnO ₄ , Co ₃ O ₄ , PdO, LaCoO ₃ , NiCo ₂ O ₄ , Ca ₂ Mn ₃ O ₈ , ZrO ₂ , Al ₂ O ₃ , B ₂ O ₃ , V ₂ O ₅ , Cr ₃ O ₄ , CeO ₂ , Pr ₆ O ₁₁ , Nd ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₄ O ₇ , Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , Yb ₂ O ₃ , Lu ₂ O ₃ , Ag ₂ V ₄ O ₁₁ , Ag ₂ O, Li _0.3 La _0.57 TiO ₃ , LiV ₃ O ₈ , RuO ₂ , IrO ₂ , MnO ₂ , InTaO ₄ , ITO, IZO, InTaO ₄ , MgO, Ga ₂ O ₃ , CaCu ₃ Ti _{4 O 12, Ag 3 PO 4} , BaTiO 3, NiTiO 3, SrTiO 3, Sr 2 Nb 2 O 7, Sr 2 Ta 2 O 7 and _{Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2} O more than one or two selected from _3-7 It can be composed of various composite materials.

In addition, in step (f), after dispersing the multi-channel metal oxide nanofibers in which the nano-sized catalyst synthesized in step (e) is bound and dispersing it in a solvent, the dispersion solution is prepared in advance for a resistance change type gas sensor. This is a step of coating on the sensor electrode using at least one coating process of spin coating, drop coating, ink-jet printing, and dispensing. Any coating method can be used as long as the sensing material can be uniformly coated on the sensor electrode.

Here, the size of the nanoparticle catalyst bound to the synthesized nanofibers has a range of 1-5 nm, and the diameter of the nanofibers has a range of 300-500 nm. In addition, the size of one channel existing inside the nanofibers has a range of 10-50 nm, and the number has a range of 5-20.

In the case of the synthesized sensing material, the nanoparticle catalyst of 5 nm or less is functionalized by being uniformly bound to the inner multichannel and surface of the nanofiber, and as the multichannel is formed, the specific surface area is increased to increase the gas reaction, Since the gas can diffuse inside the nanofiber, it provides an efficient gas reaction, and the catalyst particles present inside the nanofiber are functionalized to maximize the effect of the catalyst.

As described above, the nanoparticle catalysts having a size range of 1-5 nm are embedded in the inner hollow of apoferritin, and the two polymer composite spinning solutions in which the apoferritin containing the nanoparticle catalyst is not mixed with each other as a metal oxide precursor / After mixing, electrospinning may be performed to uniformly bind apoferrin with a nanoparticle catalyst on the surface and inside of the metal oxide precursor / polymer composite nanofiber. During electrospinning, the phase separation of the two polymers results in a large number of second polymer fibers occupying a discontinuous phase inside the first polymer fibers occupying the continuous phase of the nanofibers, and the metal oxide precursor is a first polymer that can be mixed. Aperferrin coexisting in the fiber and embedded with the nanoparticle catalyst may be uniformly contained on the surface and inside of the nanofiber. Subsequently, through the high-temperature heat treatment process, the second polymer is thermally decomposed to leave multiple channels inside the fiber, and the metal oxide precursor is oxidized and crystallized while maintaining the multi-channel shape, and the apoferritine is thermally decomposed to cause fine pores in the nanofiber. The nanoparticle catalyst, which was included in the inner hollow, is uniformly bound to the surface of the nanofiber and the multi-channel inside, so that a functional sensing material for a gas sensor can be synthesized in large quantities.

Here, since the nanoparticle catalysts are uniformly bound to a very small size (1-5 nm), the effect of the catalyst appearing when the gas reacts with the nanofibers can be maximized, and the catalyst particles aggregate together even at a high operating temperature. It did not increase the stability of the gas sensor. In addition, a metal oxide having a small particle size is formed by the role of the second polymer in a high-temperature heat treatment process, which maximizes resistance change depending on the presence or absence of gas, and brings high-sensitivity characteristics that can detect even a very small amount of gas. In addition, through a structure in which multiple channels are formed inside the nanofiber, an increased specific surface area is obtained, and the gas can easily penetrate the inside of the nanofiber, thereby providing an efficient gas reaction. Sensing characteristics were significantly increased by maximizing the effect of the catalyst by enabling the contact of.

Figure 1 is a nanoparticle catalyst 122 according to an embodiment of the present invention is embedded apoferritin 121 is decomposed after high temperature heat treatment and the nanoparticle catalyst is uniformly bonded to the multi-channel inner and outer surfaces of the nanofibers to functionalize It shows a schematic diagram of the gas sensor member 100 using the multi-channel metal oxide nanofiber 110. The nanoparticle catalyst with a very small size of 1-5 nm is uniformly contained inside and outside of the nanofiber, and is characterized by showing excellent gas sensing characteristics.

Through the gas sensor member 100 using the multi-channel metal oxide nanofibers to which the nano-sized catalyst particles are bound, a sensor having excellent sensitivity and selective detection ability for a specific gas is realized, and a living body included in a person's exhalation Selective detection of surface gas enables early diagnosis and daily diagnosis of disease. In addition, it is possible to effectively control the catalytic properties by quantitatively controlling the amount of catalyst contained in the multi-channel nanofibers, and detecting various types of gases through the synthesis of various types of nanoparticle catalyst / metal oxide composite multi-channel nanofibers. It is possible to simply manufacture a member for a gas sensor that can be used for.

Figure 2 shows a flow chart of a method for manufacturing a gas sensor using a multi-channel metal oxide nanofiber structure functionalized with nano-sized catalysts uniformly bound to the inner multichannel and outer surfaces of nanofibers according to an embodiment of the present invention. As can be seen in the flow chart, the gas sensor manufacturing method comprises the steps of binding the nanoparticle catalyst to the inner hollow of apoferritin (S210), the metal oxide precursor / two polymer electrospinning solution containing the nanoparticle catalyst embedded therein. Adding to the step of preparing a composite electrospinning solution (S220), the first polymer / discontinuous phase occupying the apoferritin / metal oxide precursor / continuous phase in which the nanoparticle catalyst is embedded by using the electrospinning method of the mixed solution prepared above Synthesizing a composite nanofiber composed of a second polymer that occupies (S230), the nanoparticle catalyst is uniformly bound to the inner multichannel and outer surface of the nanofiber through high temperature heat treatment of the synthesized composite nanofiber, and the functionalized multi It may be configured to include the step of manufacturing the channel metal oxide nanofibers (S240). Hereinafter, each step will be described in more detail.

First, look at the step (S210) of binding the nanoparticle catalyst to the inner hollow of apoferritin. The apoferritin used in this step is an animal protein and has a hollow structure with an outer diameter of 12 nm and an inner diameter of 8 nm. One or two or more catalytic metal ions may be embedded in the internal hollow structure, and nanoparticles having a diameter range of 1-5 nm may be formed through a reduction process. In order to embed the catalytic metal ions into the inner hollow of apoferritin, the catalytic metal ion is diffused into the inner hollow of apoferritin by adding a catalytic metal salt to the solution in which the apoferritin is dissolved, and a reducing agent is added to catalyze the catalytic metal ion into the catalytic metal particles Reduce to. Representative metal salts used to embed metal ions in the hollow inside of apoferritin, platinum (IV) chloride, platinum (II) acetate, gold (I, III) chloride, gold (III) acetate, silver chloride, silver acetate , Iron (III) chloride, Iron (III) acetate, Nickel (II) chloride, Nickel (II) acetate, Ruthenium (III) chloride, RutheniumAcetate, Iridium (III) chloride, Iridium acetate, Tantalum (V) chloride, Palladium ( II) chloride, Lanthanum (III) acetate, Copper (II) sulfate, and Rhodium (III) chloride. Metal salts containing metal ions that can diffuse inside the hollow are not limited. Using these metal salts, the embedded metal ions undergo a reduction process, Pt, Au, Ag, Fe, Ni, Ru, Ir, Ta, Pd, La, Cu, Rh, Co, Cr, Zn, W, Sn, Sr , In, Pb, V, Sb, Sc, Ti, Mn, Ga and Ge. Reducing agents for reducing metal ions include sodium borohydride (NaBH ₄ ), lithium aluminum hydride (LiAlH ₄ ), nascent (atomic) hydrogen, zinc-mercury amalgam (Zn (Hg)), oxalic acid (C ₂ H ₂ O ₄ ), formic acid (HCOOH), ascorbic acid (C ₆ H ₈ O ₆ ), sodium amalgam, diborane, and iron (II) sulfate, etc., which are reduced using at least one reducing agent. The final synthesized, nanoparticle catalyst-embedded apoferritin is prepared by centrifugation and washing, followed by dispersion in a solvent.

Subsequently, a step (S220) of preparing a polymer composite electrospinning solution of apoferritin / metal oxide precursor / two kinds in which a nanoparticle catalyst is embedded by adding the synthesized apoferritin is examined. In this step (S220), by utilizing the apoferritin embedded with the nanoparticle catalyst prepared in S210, to prepare a metal oxide precursor / two polymer composite electrospinning solution in which they are uniformly dispersed. Here, the two polymers are soluble in one solvent but have properties that cannot be mixed with each other. Two polymers that are not mixed with each other include polyvinylpyrolidone and polyacrylonitrile, poly (styreneacrylonitrile) and polyacrylonitrile, cellulose acetate and polyacrylonitrile, poly (methylmethacrylate) and polyacrylonitrile, polystyrene and polyacrylonitrile and poly (ethylene oxide) and polyacrylonitrile. In these two polymers, phase separation occurs in one solvent into a first polymer that occupies a continuous phase and a second polymer that occupies a discontinuous phase. The weight ratio of the second polymer may be variously adjusted in a range of 50-150% relative to the weight of the first polymer. In addition, the metal oxide precursor used in this step is typically a metal containing acetate, nitrate, chloride, acetylacetonate, methoxide, ethoxide, butoxide, isopropoxide, sulfide, etc. As long as it is a precursor that forms a metal oxide having the characteristics of the gas sensor sensor, it is not limited to a specific metal salt. The solvent used in this step is a compatible solvent such as N, N'-dimethylformamide, dimethyl sulfoxide, N, N'-dimethylacetamide, N-methylpyrrolidone, deionized water, ethanol, etc. A solvent that can simultaneously dissolve two polymers that are not mixed with each other should be selected.

In the process of preparing the electrospinning solution, after the metal oxide precursor and the first polymer are sufficiently dissolved in a solvent, the second polymer is added to dissolve and stirred for 5 to 24 hours, and finally the process (S210) is performed. The nanoparticle catalyst synthesized through is added and mixed with apoferritin. Finally, the mixture is stirred for 2 hours to 6 hours so that the two polymers with a nanoparticle catalyst-embedded apoferritin, a metal oxide precursor, are uniformly mixed in the solution.

Subsequently, the composite solution prepared above is synthesized by using the electrospinning method to synthesize a composite nanofiber composed of a first polymer occupying a nanoparticle catalyst embedded apoferritin / metal oxide precursor / continuous phase / second polymer occupying the discontinuous phase Step S230 is performed. In performing the electrospinning method, the nanoparticle catalyst prepared above is filled with apoferritin / metal oxide precursor / two polymer composite electrospinning solution in a syringe, and then the syringe is pumped at a constant speed using a syringe pump. By pushing, a certain amount of spinning solution is discharged per unit time. The electrospinning system may include a high voltage generator, a grounded conductive substrate, a syringe, and a syringe pump, and a syringe needle is applied by applying a high voltage (5-30 kV) electric field between the needle end of the syringe filled with the solution and the conductive substrate. The spinning solution discharged through is transformed into a nanofiber form and integrated on a conductive substrate. The discharge rate can be variously adjusted to about 0.01 ml / min to 0.5 ml / min, and apoferritin with a nanoparticle catalyst having a desired size can be adjusted by adjusting the diameter or length of the nanofibers through the control of the voltage and the discharge amount. / Metal oxide precursor / Composite nanofibers composed of two polymers can be produced. In the electrospinning of this step, due to the phase separation phenomenon of two polymers that are not mixed with each other, a plurality of second polymer fibers occupying a discontinuous phase are present inside the first polymer fibers occupying the continuous phase of the nanofibers, and the metal oxide precursor Is present with the first polymer that can be mixed, and because of the excellent dispersibility of apoferritin with a nanoparticle catalyst embedded therein, the nanoparticles / apoferritin are uniformly distributed inside and on the surface of the composite nanofiber.

Finally, the step of manufacturing the multi-channel metal oxide nanofibers functionalized by uniformly bonding the nanoparticle catalysts to the multi-channel metal oxide inner and outer surfaces of the multi-channel metal oxide by heat-treating the produced composite nanofiber (S240). Perform. In this step, heat treatment is performed in a temperature range of 500-700 ° C to thermally decompose the polymer and apoferritin, forming multiple channels inside the nanofiber, and the nanoparticle catalyst embedded in the apoferritin inside and outside the nanofiber. Make sure to adhere evenly. In the process of heat treatment, the second polymer occupying the discontinuous phase is decomposed to leave a multi-channel, and the metal oxide precursor is oxidized and crystallized while maintaining the multi-channel form, and the apoferritin is decomposed to include nanoparticles in the inner hollow Multichannel metal oxide nanofibers in which the catalyst is uniformly bound to the multichannel of the nanofibers and the outer surface are synthesized. In this heat treatment process, since the temperature at which the second polymer is thermally decomposed is higher than the crystallization temperature of the metal oxide precursor by 50-150 ° C., heat transferred to the metal oxide particles decreases, and a number of second polymer fibers are formed of nanofibers. The growth of metal oxide particles is suppressed according to the support from the inside, thereby forming a metal oxide having a small particle size of 1 to 20 nm. In addition, the apoferritin is an animal protein composed of an outer diameter of 12 nm and an inner diameter of 8 nm, and is characterized by leaving micropores having a size range of 1 to 15 nm in nanofibers as the protein shell decomposes during the heat treatment process. In addition, the nanoparticle catalyst contained in the hollow structure of apoferritin is Pt, PtO, PtO ₂ , Au, Ag, Fe ₂ O ₃ , NiO, RuO ₂ , IrO ₂ , Ta ₂ O ₅ , PdO, PdO ₂ after heat treatment , CuO, Rh ₂ O ₃ , Co ₃ O ₄ , Cr ₂ O ₃ , ZnO, WO ₃ , SnO ₂ , SrO, In ₂ O ₃ , PbO, V ₂ O ₅ , VO ₂ , VO, Sb ₂ O ₃ , It is substituted with at least one nanoparticle catalyst of Sc ₂ O ₃ , TiO ₂ , MnO ₂ , Ga ₂ O ₃ and GeO ₂ . In addition, the metal oxide nanofiber formed in this step is ZnO, SnO ₂ , WO ₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , NiO, TiO ₂ , CuO, In ₂ O ₃ , Zn ₂ SnO ₄ , Co ₃ O ₄ , PdO, LaCoO ₃ , NiCo ₂ O ₄ , Ca ₂ Mn ₃ O ₈ , ZrO ₂ , Al ₂ O ₃ , B ₂ O ₃ , V ₂ O ₅ , Cr ₃ O ₄ , CeO ₂ , Pr ₆ O ₁₁ , Nd ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₄ O ₇ , Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , Yb ₂ O ₃ , Lu ₂ O ₃ , Ag ₂ V ₄ O ₁₁ , Ag ₂ O, Li _{0 . 3} La _{0 . 57} TiO ₃ , LiV ₃ O ₈ , RuO ₂ , IrO ₂ , MnO ₂ , InTaO ₄ , ITO, IZO, InTaO ₄ , MgO, Ga ₂ O ₃ , CaCu ₃ Ti ₄ O ₁₂ , Ag ₃ PO ₄ , BaTiO ₃ , _{NiTiO 3, SrTiO 3, Sr 2} Nb 2 O 7, Sr 2 Ta 2 O 7 and Ba _{0. 5} Sr _{0 . 5} Co _{0 . 8} Fe _{0 . 2} O _{3 -} and it may be variously configured with one or more composites selected from the group consisting of _7.

3 schematically shows a manufacturing process sequence according to a method of manufacturing a member for a gas sensor using a multi-channel metal oxide nanofiber with a nano-sized catalyst bound using an electrospinning method according to an embodiment of the present invention.

In the first step (S310), a nanoparticle catalyst-embedded apoferritin / metal oxide precursor / composite electrospinning solution composed of two polymers is electrospinned to uniformly disperse the apoferritin containing the nanoparticle catalyst. An example of producing a composite nanofiber is shown.

The second step, step S320, shows a process of heat-treating the composite nanofibers synthesized in step S310 at a high temperature. The second polymer occupying the discontinuous phase is thermally decomposed, leaving a large number of channels inside the nanofibers, apoferritin decomposition, and the embedded nanoparticle catalysts are uniformly bound to the nanofibers.

Hereinafter, the present invention will be described in detail through examples and comparative examples. The examples and comparative examples are only for illustrating the present invention, and the present invention is not limited to the following examples.

Example  1: Preparation of apoferritin containing Pt nanoparticle catalyst

First, 0.5 g of apoferritin is treated with a sodium hydroxide (NaOH) solution (0.1 mol / L) to adjust the pH to 8.5. Thereafter, a separately prepared aqueous solution of Pt precursor (H ₂ PtCl ₆ H ₂ O) (1.6 wt%) was added to the apoferritin solution and stirred at room temperature at a rate of 100 rpm for 1 hour or 3 hours to give the Pt ion apoferritin. Allow to diffuse into the internal hollow structure. Subsequently, in order to reduce the Pt ions embedded in apoferritin to Pt particles, an aqueous sodium borohydride (NaBH ₄ ) solution (0.1 mol / L) is added and stirred at room temperature at a rate of 200 rpm for 10 to 30 minutes. Thereafter, the agitated solution is centrifuged to separate the apoferritine containing Pt nanoparticles from the solution, and washed with ethanol. After performing the centrifugation and ethanol washing process three or more times, the collected apoferritin is dispersed in a solution of 2.5 g of N, N'-dimethylformamide (D, NMF), and the prepared dispersion is It is used when preparing electrospinning solution.

Figure 4 shows a transmission electron microscope image of the apoferritin embedded Pt nanoparticle catalyst prepared by the above process. It can be seen that the synthesized Pt nanoparticles have a size of about 5 nm.

Example  2: Pt nanoparticle catalyst utilizes apoperitin embedded, Pt nanoparticle catalyst Bound  Producing multi-channel metal oxide nanofibers

First, 0.12 g of polyvinylpyrolidone (PVP, molecular weight: 1,300,000 g / mol) and 0.15 g of tin precursor (SnCl ₂ 2H ₂ O) were mixed in 2 ml of DMF solution, and at 300 rpm for 1 to 3 hours at room temperature. Stir at speed. Thereafter, 0.18 g of polyacrylonitrile (PAN, molecular weight: 150,000 g / mol) is added and stirred at a temperature of about 70 ° C. at a rate of 300 rpm for 6 to 12 hours. Finally, 120 μL of the apoferritin dispersion synthesized in Example 1 was added to the stirred solution to prepare a final composite electrospinning solution. After transferring the prepared electrospinning solution to a syringe (Henke-Sass Wolf, 10 mL NORM-JECT ^ⓡ ), connect it to a syringe pump, push it at a discharge rate of 0.15 ml / min, and press the syringe needle (needle, 21 gauge) and When a high voltage of 15 kV is applied between stainless steel (stainless use steel), a composite nanofiber composed of apoferritin / tin precursor / PVP / PAN with Pt nanoparticles embedded therein is synthesized.

FIG. 5 is a scanning electron microscope photograph of a composite nanofiber composed of apoferritin / tin precursor / PVP / PAN with embedded Pt nanoparticles collected after electrospinning. The diameter of the synthesized nanofibers ranges from 700 to 900 nm, and it can be seen that the surface of the nanofibers is uneven. It can be seen that the phase separation phenomenon of the two polymers that are not mixed with each other occurs through the shape of the surface.

The composite nanofibers composed of apoferritin / tin precursor / PVP / PAN with embedded Pt nanoparticles prepared in the same manner were maintained at 280 ° C. for 1 hour at a heating rate of 5 ° C./min, followed by 600 ° C. After holding for an hour, the mixture was cooled to room temperature at a rate of 40 ° C / min. The heat treatment was performed in an air atmosphere using Ney's Vulcan 3-550 small electric furnace. Here, the reason for heat treatment at 280 ° C. for one hour is to stabilize the PAN, and conditions may vary depending on the type of polymer. In addition, during heat treatment at 600 ° C., organic substances (apoferritin, PVP, PAN) are decomposed, tin precursors are oxidized and crystallized, and Pt nanoparticle catalysts are bound to form functionalized multi-channel Pt-SnO ₂ nanofibers.

6 shows a scanning electron microscope photograph of the multi-channel Pt-SnO ₂ nanofiber synthesized in Example 2. The synthesized nanofibers have a reduced diameter of 300 to 400 nm as organic matter decomposes. It can be seen that the number of channels of the multi-channel Pt-SnO ₂ nanofibers has a range of 5 to 20 per one nanofiber, and the diameter of the channel has a range of 10 to 50 nm.

7 shows transmission electron micrographs and composition analysis results of the multi-channel Pt-SnO ₂ nanofibers synthesized in Example 2. Transmission electron microscopy clearly shows the presence of multiple channels in the nanofiber. In addition, the transmission electron microscope lattice analysis shows that the Pt nanoparticle catalyst is SnO ₂ It shows that it is bound to nanofibers and shows that SnO ₂ is crystallized through electron diffraction analysis. In addition, through the transmission electron microscope component analysis (EDS), it can be confirmed that Pt is evenly dispersed in SnO ₂ nanofibers without aggregation between each other, and as the line component analysis shows a continuous zigzag form, the multi-channel structure is clearly confirmed. You can.

Comparative example  1. Pt nanoparticle catalyst Bound SnO ₂  Nano fiber

A comparative example that can be compared with Example 2 is an apoferritin-based nanoparticle catalyst-bound SnO ₂ nanofiber structure. 0.30 g of PVP and 0.15 g of tin precursor are mixed in 2 ml of DMF solution and stirred at room temperature at a rate of 300 rpm for 6 to 10 hours. To the stirred solution, 120 μl of the apoferritin dispersion synthesized in Example 1 was added to prepare a final composite electrospinning solution. After transferring the prepared electrospinning solution to a syringe (Henke-Sass Wolf, 10 mL NORM-JECT ^ⓡ ), connect it to a syringe pump, push it at a discharge rate of 0.15 ml / min, and press the syringe needle (needle, 21 gauge) and When a high voltage of 15 kV is applied between stainless steel (stainless use steel), a composite nanofiber composed of apoferritin / tin precursor / PVP with Pt nanoparticle catalyst embedded in the current collector is synthesized. The apoferritin / tin precursor / PVP composite nanofiber containing the Pt nanoparticle catalyst was maintained at 600 ° C for one hour at a rate of temperature increase of 5 ° C / min, and then cooled to room temperature at a rate of 40 ° C / min. The heat treatment was performed in an air atmosphere using Ney's Vulcan 3-550 small electric furnace. During heat treatment at 600 ° C., PVP is thermally decomposed, apoferritin is decomposed, and the embedded nanoparticle catalyst is bound to the inside and outside of the nanofiber, and the tin precursor is oxidized and crystallized to synthesize Pt-SnO ₂ nanofiber.

FIG. 8 shows a scanning electron microscope photograph of SnO ₂ nanofibers in which the Pt nanoparticle catalyst prepared in Comparative Example 1 was bound. The average diameter of the synthesized SnO ₂ nanofibers is about 250 nm, and unlike the multi-channel SnO ₂ nanofibers prepared in Example 2, a nanofiber structure without a channel was formed.

Wherein the produced Pt nanoparticle catalysts binder SnO ₂ nanofibers was used to compare the detected characteristics for a wide gas with a second embodiment the catalyst is a Pt nanoparticle binder in the production of multi-channel SnO ₂ nanofibers.

Comparative example  2. Pt nanoparticle catalyst Not bound  Multichannel SnO ₂  Nano fiber

A comparative example that can be compared with Example 2 is a multi-channel SnO ₂ nanofiber structure in which Pt nanoparticle catalyst is not bound. 0.12 g of PVP and 0.15 g of tin precursor are mixed in 2 ml of DMF solution and stirred at room temperature for 1 hour or 3 hours at a rate of 300 rpm. Thereafter, 0.18 g of PAN is added and stirred at a temperature of about 70 ° C. at a rate of 300 rpm for 6 to 12 hours to prepare a final composite electrospinning solution. After transferring the prepared electrospinning solution to a syringe (Henke-Sass Wolf, 10 mL NORM-JECT ^ⓡ ), connect it to a syringe pump, push it at a discharge rate of 0.15 ml / min, and press the syringe needle (needle, 21 gauge) and When a high voltage of 15 kV is applied between stainless steel (stainless use steel), a composite nanofiber composed of tin precursor / PVP / PAN is synthesized on the current collector.

After the composite nanofibers composed of tin precursor / PVP / PAN prepared by the above method were heated at a rate of 5 ° C./min for 1 hour at 280 ° C., and then maintained at 600 ° C. for another hour, 40 It cooled to room temperature at a descending rate of ℃ / min. The heat treatment was performed in an air atmosphere using Ney's Vulcan 3-550 small electric furnace. Here, the reason for heat treatment at 280 ° C. for one hour is to stabilize the PAN, and conditions may vary depending on the type of polymer. In addition, during heat treatment at 600 ° C., organic substances (PVP, PAN) are decomposed, and the tin precursor is oxidized and crystallized to form multi-channel SnO ₂ nanofibers.

The produced multi-channel SnO ₂ nanofibers in which the Pt nanoparticle catalyst is not bound are used to compare the sensing characteristics for multiple gases together with the multi-channel SnO ₂ nanofibers in which the Pt nanoparticle catalyst prepared in Example 2 is bound. Did.

Comparative example 3. Pt  Nanoparticle catalyst Not bound  Not SnO ₂  Nano fiber

As a comparative example that can be compared with Example 2, there is an SnO ₂ nanofiber structure in which an apoferritin-based nanoparticle catalyst is not bound. 0.30 g of PVP and 0.15 g of tin precursor are mixed in 2 ml of DMF solution and stirred at room temperature at a rate of 300 rpm for 6 to 10 hours. After transferring the prepared electrospinning solution to a syringe (Henke-Sass Wolf, 10 mL NORM-JECT ^ⓡ ), connect it to a syringe pump, push it at a discharge rate of 0.15 ml / min, and press the syringe needle (needle, 21 gauge) and When a high voltage of 15 kV is applied between stainless steel (stainless use steel), a composite nanofiber composed of a tin precursor / PVP is synthesized on the current collector. The tin precursor / PVP composite nanofiber was maintained at 600 ° C. for one hour at a rate of temperature increase of 5 ° C./min, and then cooled to room temperature at a rate of 40 ° C./min. The heat treatment was performed in an air atmosphere using Ney's Vulcan 3-550 small electric furnace. During heat treatment at 600 ° C., PVP is thermally decomposed, and the tin precursor is oxidized and crystallized to synthesize SnO ₂ nanofibers.

9 shows a scanning electron microscope photograph of SnO ₂ nanofibers in which the Pt nanoparticle catalyst synthesized in Comparative Example 3 is not bound. The average diameter of the synthesized SnO ₂ nanofibers is about 250 nm, and unlike the multi-channel SnO ₂ nanofibers prepared in Example 2, the pores in the form of channels are not seen. This result shows the role of two polymers that are not mixed with each other in forming a multi-channel structure.

The prepared SnO ₂ nanofibers in which the Pt nanoparticle catalyst was not bound were used to compare the sensing characteristics for various gases together with the multi-channel SnO ₂ nanofibers in which the Pt nanoparticle catalyst prepared in Example 2 was bound.

Experimental example  One. PVP / Apoferritin containing tin oxide precursor composite nanofiber and Pt nanoparticle catalyst / PVP / PAN / tin oxide precursor Confirm the change in mass and the degree of heat transfer according to the heat treatment of the composite nanofiber

As can be seen from the scanning electron micrographs, the nanofibers prepared in Comparative Example 3 show a particle size of about 20 nm, whereas the multi-channel nanofibers prepared in Example 2 show a small particle size of about 10 nm. . In order to determine the cause of this, according to the heat treatment of the PVP / tin oxide precursor composite nanofibers prepared in Comparative Examples 3 and 2 and Pt nanoparticle catalyst according to the heat treatment of the apoferritin / PVP / PAN / tin oxide precursor composite nanofibers The change in mass and the degree of heat transfer were confirmed. Each of the nanofibers of 0.05 g was heat-treated in an air atmosphere from room temperature to 700 ° C with a heating rate of 5 ° C / min, and the change in mass and the degree of heat transfer were determined.

10 is an Experimental Example 1 of the present invention, according to Comparative Examples 3 and 2, to form a multi-channel SnO ₂ nanofibers in which Pt nanoparticle catalyst is bound and SnO ₂ nanofibers in which Pt nanoparticle catalyst is not bound In the process, it is a graph showing the change in mass and the degree of heat transfer according to the heat treatment of the apoferritin / PVP / PAN / tin oxide precursor composite nanofiber containing the PVP / tin oxide precursor composite nanofiber and Pt nanoparticle catalyst. In the case of PVP / tin oxide precursor composite nanofibers, the mass loss occurring at 400 ° C or higher is about 20%, whereas in the case of apoferritin / PVP / PAN / tin oxide precursor composite nanofibers containing Pt nanoparticle catalyst In, it can be seen that the mass loss occurring at 400 ° C or higher is about 45%. This can be regarded as a difference depending on the presence or absence of PAN, as previously reported, PVP decomposes below 450 ° C and PAN decomposes above 450 ° C. In addition, crystallization of SnO ₂ starts at 400 ° C. That is, in the case of apoferritin / PVP / PAN / tin oxide precursor composite nanofibers, as the decomposition of PAN occupying the discontinuous phase inside the nanofibers occurs at a temperature higher than the crystallization of SnO ₂ , the heat transferred to the SnO ₂ particles It is reduced, and the growth of SnO ₂ particles is suppressed as a number of PAN fibers are supported therein to form SnO ₂ having a small particle size.

Experimental example  2. Pt nanoparticle catalyst Bound  Multi-channel SnO ₂  Nanofiber, Pt nanoparticle catalyst Bound SnO ₂  Nanofiber, Pt nanoparticle catalyst Not bound  Multichannel SnO ₂  Nanofiber and Pt nanoparticle catalyst Not bound  Not SnO ₂  Gas sensor manufacturing and property evaluation using nanofibers

In order to utilize the sensing materials prepared in Examples 1 and 2 and Comparative Examples 1, 2 and 3 in the gas sensor for exhalation analysis, multi-channel SnO ₂ nanofibers and Pt nanoparticle catalysts in which Pt nanoparticle catalysts are bound are used. in which the binder of SnO ₂ nanofibers, Pt nanoparticle catalyst is not a binding multichannel SnO ₂ nanofibers, and dispersing SnO ₂ the Pt nanoparticle catalyst is not a binding nanofibers to 5 mg ethanol 250 μL each after 1 hour During the ultrasonic cleaning process, the grinding process is performed. Subsequently, a multi-channel SnO ₂ nanofiber with a Pt nanoparticle catalyst dispersed in the ethanol produced using a micropipette, a SnO ₂ nanofiber with a Pt nanoparticle catalyst, and a multi-particle without a Pt nanoparticle catalyst Channel SnO ₂ nanofibers, and StO ₂ nanofiber solution without Pt nanoparticle catalyst are coated on a 3 mm x 3 mm alumina (Al ₂ O ₃ ) substrate patterned with parallel gold (Au) electrodes. After that, it is dried on a hot plate at 60 ° C. By repeating this process 3 to 5 times, a sufficient amount of nanofibers was uniformly coated on the alumina sensor substrate.

In order to evaluate the characteristics of the manufactured gas sensor, the driving temperature of the sensor is maintained at 400 ° C in a humid environment (95% RH), and the concentration of acetone (CH ₃ COCH ₃ ) gas is 5, 4, 3, 2, Acetone detection characteristics were evaluated by changing to 1, 0.6 and 0.4 ppm. In addition, in this Experimental Example 2, as well as acetone gas, which is a typical example of a volatile organic compound gas, ethanol (C ₂ H ₅ OH), methane (CH ₄ ), carbon monoxide (CO), ammonia (NH ₃ ), formaldehyde (HCHO) , Hydrogen sulfide (H ₂ S), toluene (C ₆ H ₅ CH ₃ ), etc. were also evaluated for the detection characteristics to evaluate the selective gas detection capability.

Figure 11 decreases the concentration of acetone gas at 400 ℃ from 5 ppm to 0.4 ppm over time and the degree of reaction (R _air / R _{gas ,} where R _air is the resistance value of the gas sensor when air is injected, R _gas Is the resistance value of the gas sensor when acetone gas is injected). As shown in FIG. 11, the multi-channel SnO ₂ nanofibers in which the Pt nanoparticle catalyst is bound are SnO ₂ nanofibers in which the Pt nanoparticle catalyst is bound to 5 ppm of acetone gas, and the multi-channel in which the Pt nanoparticle catalyst is not bound SnO ₂ nanofibers and Pt nanoparticle catalyst showed improved sensitivity characteristics more than 8 times than SnO ₂ nanofibers without binding. This clearly shows the effect of the multi-channel structure and the uniformly dispersed nano-sized catalyst.

Figure 12 is when the concentration of acetone, 1, 2, 3, 4, 5 ppm il eseo 400 ℃, Pt nanoparticle catalyst is a binder multichannel SnO ₂ nanofibers, Pt nanoparticle catalysts binder SnO ₂ nanofibers, Pt This is a result of evaluating the properties of the multichannel SnO ₂ nanofibers without a nanoparticle catalyst, and the reaction rate of the SnO ₂ nanofiber-based gas sensor without a Pt nanoparticle catalyst. As shown in the results, it can be seen that the reaction rate of the multi-channel nanofiber structure is very fast within 12 seconds, while the reaction rate of the general nanofiber structure is relatively slow within 28 seconds. These results show that the multi-channel structure promotes gas infiltration into the nanofibers, inducing an instantaneous resistance change, causing a rapid reaction.

FIG. 13 shows the degree of reaction of acetone, ethanol, methane, carbon monoxide, ammonia, formaldehyde, hydrogen sulfide, and toluene to 1 ppm of a multi-channel SnO ₂ nanofiber with a Pt nanoparticle catalyst measured at 400 ° C. As shown in FIG. 13, the multi-channel SnO ₂ nanofiber-based gas sensor in which the Pt nanoparticle catalyst is bound exhibits a reaction level of less than 9.1 on ethanol, methane, carbon monoxide, ammonia, formaldehyde, hydrogen sulfide, and toluene gas, whereas acetone It showed a very good reaction level of 22 or higher, which confirmed the selective gas detection ability.

FIG. 14 shows the results of repeated evaluation of sensing characteristics for 1 ppm acetone of a multi-channel SnO ₂ nanofiber-based gas sensor bound with a Pt nanoparticle catalyst at 400 ° C. As shown in the results, it showed stable sensing characteristics even after 30 repetitive reactions and recovery. Through this, it was confirmed that the multi-channel SnO ₂ nanofiber-based gas sensor bound with the Pt nanoparticle catalyst has the ability to stably detect for a long time, and has stability that does not decrease the detection ability even after several detections.

The above experimental example showed the sensor characteristics of a multi-channel SnO ₂ nanofiber-based gas sensor in which a Pt nanoparticle catalyst with high sensitivity, fast reaction speed, and selectivity to acetone was bound. In addition, by changing the types of the nanoparticle catalyst and the metal oxide material, a change in gas selectivity can be expected, thereby synthesizing multiple types of multi-channel metal oxide nanofibers in which multiple types of nanoparticle catalyst particles are bound, and Gas sensor arrays with high sensitivity and selectivity can be manufactured. The multi-channel metal oxide nanofiber sensing material including the nanoparticle catalyst realized through the apoferritin can be used in a gas sensor for healthcare for analysis and diagnosis of volatile organic compound gas in exhalation.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and variations without departing from the essential characteristics of the present invention. Therefore, the embodiments described in the present invention are not intended to limit the technical spirit of the present invention, but to explain them, and are not limited to these embodiments. The scope of protection of the present invention should be interpreted by the claims below, and all technical spirits within the equivalent ranges should be interpreted as being included in the scope of the present invention.

100: member for multi-channel metal oxide nanofiber gas sensor with nano-sized catalyst
110: Multi-channel metal oxide nanofibers functionalized with nanoparticle catalysts uniformly bound to the multi-channel internal and external surfaces of nanofibers
121: apoferritin with nanoparticle catalyst embedded in the hollow
122: After high temperature heat treatment, apoferritine is thermally decomposed and bound nanoparticle catalyst

Claims (20)

The metal oxide precursor is oxidized and crystallized by heat treatment on a composite nanofiber comprising apoferritin containing a nanoparticle catalyst in an interior hollow, two polymers that are not mixed with each other, and a metal oxide precursor to form metal oxide nanofibers, , As the multi-channel by phase separation of the two polymers is formed inside the metal oxide nanofiber, and the apoferrin is removed by the heat treatment, the inside of each of the multi-channel and the metal oxide nanofiber outer surface The nanoparticle catalyst is bound and functionalized,
The composite nanofibers include a first polymer fiber in which the metal oxide precursor is mixed while occupying a continuous phase of the nanofibers by phase separation of the two polymers, and occupy a discontinuous phase inside the first polymer fiber. It further comprises a plurality of second polymer fibers, and further comprises the apoferritin on the surface and inside,
In the process of heat treatment for the composite nanofibers, as the thermal decomposition of a plurality of second polymer fibers occupying a discontinuous phase occurs at a temperature higher than the crystallization of the metal oxide precursor, the heat transferred to the metal oxide particles is reduced. Multi-channel metal oxide nanofibers, characterized in that the size of the metal oxide particles is limited. delete According to claim 1,
In the process of thermally decomposing the first polymer fiber and the second polymer fiber through the heat treatment, the metal oxide precursor is oxidized to a metal oxide in the form of a multichannel formed inside the nanofiber by removing the second polymer fiber. While maintaining crystallization, the apoferritine is thermally decomposed to form pores in the nanofibers, and at the same time, the nanoparticle catalyst contained in the hollow inside of the apoferritin is attached to the surface of the nanofibers and the inside of each of the multichannels. Multi-channel metal oxide nanofiber. delete According to claim 1,
Pyrolysis of the second polymer fiber is multi-channel metal oxide nanofibers, characterized in that occurs at a relatively higher temperature than the temperature included in the range of 50-150 ℃ than the crystallization of the metal oxide precursor. The metal oxide precursor is oxidized and crystallized by heat treatment on a composite nanofiber comprising apoferritin containing a nanoparticle catalyst in an interior hollow, two polymers that are not mixed with each other, and a metal oxide precursor to form metal oxide nanofibers, , As the multi-channel by phase separation of the two polymers is formed inside the metal oxide nanofiber, and the apoferrin is removed by the heat treatment, the inside of each of the multi-channel and the metal oxide nanofiber outer surface The nanoparticle catalyst is bound and functionalized,
Multi-channel metal oxide nanofibers, characterized in that the size of the metal oxide particles forming the metal oxide nanofibers is included in the range of 1 to 20 nm. According to claim 1,
The two polymers include polyvinylpyrrolidone, poly (styreneacrylonitrile), polystyrene, cellulose acetate, and poly (ethylene oxide) (poly (ethylene oxide). ethylene oxide)), poly (methyl methacrylate) (poly (methylmethacrylate)), a multi-channel metal, characterized in that it consists of a combination of a first polymer and a second polymer including polyacrylonitrile (polyacrylonitrile). Oxide nanofibers. According to claim 1,
Multi-channel metal oxide nanofibers characterized in that the weight ratio of the second polymer occupying the discontinuous phase in the composite nanofiber to the weight of the first polymer occupying the continuous phase in the composite nanofiber is included in the range of 50 to 150% . According to claim 1,
The number of the multi-channel, multi-channel metal oxide nanofibers, characterized in that included in the range of 5 to 20 per one of the composite nanofibers, the diameter of the individual channels are included in the range of 10 to 50 nm. According to claim 1,
The apoferritin has a hollow structure inside, and encapsulates one or more catalytic metal ions into the hollow inside,
The multi-channel metal oxide nanofibers, characterized in that the diameter of the nanoparticle catalyst generated by reduction of the catalyst metal ions is included in a range of 1 to 5 nm. According to claim 1,
Multi-channel metal oxide nanofibers, characterized in that the weight ratio of the nanoparticle catalyst is contained in a concentration range of 0.01 to 1 wt% compared to the multi-channel metal oxide nanofibers. According to claim 1,
The nanoparticle catalyst is platinum (IV) chloride, platinum (II) acetate, gold (I, III) chloride, gold (III) acetate, silver chloride, silver acetate, Iron (III) chloride, Iron (III) acetate, Nickel (II) chloride, Nickel (II) acetate, Ruthenium (III) chloride, RutheniumAcetate, Iridium (III) chloride, Iridium acetate, Tantalum (V) chloride, Palladium (II) chloride, Lanthanum (III) acetate, Copper (II) Multi-channel metal oxide nanofibers, characterized by being formed by catalytic metal ions synthesized by including at least one metal salt selected from sulfate and Rhodium (III) chloride. According to claim 1,
The nanoparticle catalyst is Pt, Au, Ag, Fe, Ni, Ru, Ir, Ta, Pd, La, Cu, Rh, Co, Cr, as the catalytic metal ion contained in the inner hollow of the apoferritin is reduced At least one nanoparticle catalyst selected from Zn, W, Sn, Sr, In, Pb, V, Sb, Sc, Ti, Mn, Ga and Ge, and included in the inner hollow of the apoferritin,
The nanoparticle catalyst contained inside the hollow structure of apoferritin is Pt, PtO, PtO ₂ , Au, Ag, Fe ₂ O ₃ , NiO, RuO ₂ , IrO ₂ , Ta ₂ O ₅ , PdO, PdO ₂ , after heat treatment CuO, Rh ₂ O ₃ , Co ₃ O ₄ , Cr ₂ O ₃ , ZnO, WO ₃ , SnO ₂ , SrO, In ₂ O ₃ , PbO, V ₂ O ₅ , VO ₂ , VO, Sb ₂ O ₃ , Sc _{2 O 3, TiO 2, MnO} 2, Ga 2 O 3 and GeO ₂ are substituted with at least one nanoparticle catalyst in a multi-channel metal oxide nano-fibers, characterized in that the binding to the metal oxide nano-fiber external surface. A gas comprising a sensing material formed by coating multi-channel metal oxide nanofibers of any one of claims 1, 3, or 5 to 13 on a sensor electrode capable of measuring a change in resistance. sensor. In the manufacturing method of the multi-channel metal oxide nanofibers,
(a) synthesizing a nanoparticle catalyst inside the hollow structure of apoferritin;
(b) synthesizing an electrospinning solution by dissolving two polymers that are not mixed with each other in a solvent together with a metal oxide precursor;
(c) Composite electrospinning comprising apoferritin containing the synthesized nanoparticle catalyst in the synthesized electrospinning solution, and apoferritin containing the nanoparticle catalyst, a metal oxide precursor, and two polymers that are not mixed with each other. Preparing a solution;
(d) electrospinning the composite electrospinning solution to produce a composite nanofiber in which apoferritin containing a nanoparticle catalyst is bound to the surface and inside of a metal oxide precursor and a polymer composite nanofiber; And
(e) preparing the functionalized multichannel metal oxide nanofibers by heat-treating the composite nanofibers so that the nanoparticle catalyst is uniformly bound to the inner multichannels and outer surfaces of the multichannel metal oxide nanofibers.
Including,
The composite nanofiber comprises a first polymer fiber in which the metal oxide precursor is mixed while occupying a continuous phase of the nanofibers by phase separation of the two polymers, and has a discontinuous phase inside the first polymer fiber. Further comprising a plurality of second polymer fibers occupied, the surface and the inside further comprises the apoferritin,
In the process of heat treatment for the composite nanofibers, as the thermal decomposition of a plurality of second polymer fibers occupying a discontinuous phase occurs at a temperature higher than the crystallization of the metal oxide precursor, the heat transferred to the metal oxide particles is reduced. Method of manufacturing a multi-channel metal oxide nanofibers, characterized in that the size of the metal oxide particles is limited. The method of claim 15
Step (a) is,
In order to embed the nanoparticle catalyst in the hollow inside of the apoferritin, the catalyst metal salt is embedded in the solution in which the apoferritin is dissolved to embed a catalyst metal ion, and a reducing agent is added to reduce the catalyst metal ion to catalyst metal particles Method of manufacturing a multi-channel metal oxide nanofibers, characterized in that. The method of claim 15
Step (a) is,
The reducing agent for reducing the catalytic metal ion embedded in the hollow of the apoferritin, sodium borohydride (NaBH ₄ ), lithium aluminum hydride (LiAlH ₄ ), nascent (atomic) hydrogen, zinc-mercury amalgam (Zn (Hg)), Multi-channel comprising at least one of oxalic acid (C ₂ H ₂ O ₄ ), formic acid (HCOOH), ascorbic acid (C ₆ H ₈ O ₆ ), sodium amalgam, diborane and iron (II) sulfate Method for manufacturing metal oxide nanofibers. The method of claim 15,
In step (e),
In the process of thermally decomposing and removing the apoferritin and the two polymers through the heat treatment, the second polymer occupying the discontinuous phase is decomposed to form a multi-channel, and the first polymer, which is a continuous phase, is decomposed and the first polymer is decomposed. The metal oxide precursor mixed in is oxidized and crystallized while maintaining the shape of the formed multichannel, and the apoferritin is decomposed and the nanoparticle catalyst contained in the hollow is bound to the table of the inner and nanofibers of the formed multichannel. Method of manufacturing a multi-channel metal oxide nanofibers, characterized in that. The method of claim 15,
In step (e),
The apoferritin is a multi-channel metal oxide nanofiber characterized by forming pores having a size in the range of 1 to 15 nm in nanofibers as the protein shell decomposes during the heat treatment process, as a hollow structure of animal protein. Method of manufacturing. The method of claim 15,
(f) pulverizing the multi-channel metal oxide nanofibers and dispersing them in a solvent, and coating them using a coating process of at least one of spin coating, drop coating, and inkjet printing on a sensor electrode for a resistance change type gas sensor.
Method of manufacturing a multi-channel metal oxide nanofibers further comprising a.

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