KR101817015B1 - Gas sensor and member using catalyst functionalized macroporous tungsten oxide nanofibers synthesized by catalyst decorated polymeric colloid templates, and manufacturing method thereof - Google Patents

Abstract

Disclosed are a sensor material comprising a one-dimensional porous metal oxide nanofiber in which catalytic particles are uniformly transferred at a position where spherical and elliptical pores and irregular-shaped concavo-convex structures are formed on the surface, and a manufacturing method thereof. The present invention relates to a porous metal oxide nanofiber sensor material having a one-dimensional structure with maximized catalytic effect by using a block copolymer template in which catalyst nanoparticles are uniformly bound to form a plurality of pores in a finally formed gas sensing material to activate the diffusion and reaction of gas, and by uniformly transferring the catalyst nanoparticles.

Description

Technical Field [0001] The present invention relates to a method for manufacturing porous metal oxide nanofibers to which a catalyst having a functionalized polymer colloid as a template is transferred, and a gas sensor including the porous metal oxide nanofiber, thereof}

The present invention relates to a member for a gas sensor, a gas sensor using the same, and a manufacturing method thereof. More particularly, the present invention relates to a gas sensor using a spherical polymer colloid having uniformly distributed catalysts as a template, Metal oxide semiconductor nanofibers in which a large number of macropores are formed and nano-sized catalysts are uniformly transferred to pores formed, members for gas sensors using the same, gas sensors and a method for manufacturing the same.

Since gas sensing materials using metal oxides operate based on simple resistance change principle, it is possible to construct sensors without complicated circuits, so commercialized prototypes are developed to detect a large number of harmful environmental gases in a simple and compact form. In addition, since a sensor can be manufactured using only a very small amount of material, interest in developing a portable gas sensor has recently been focused. Basically, the metal oxide based gas sensing material changes its electrical resistance value by the chemical reaction occurring on the surface. Therefore, as the chemical reaction occurring on the surface is maximized, the resistance change of the metal oxide sensing material is maximized, and ultimately, a gas sensor having excellent sensing characteristics can be developed. From this point of view, the surface area of the metal oxide sensing material must be maximized to maximize the chemical reaction area occurring on the surface, and a material having high sensing properties can be developed. In addition, it can be said that the structure in which the metal oxide sensing material includes a plurality of pores can exhibit a high sensitivity sensing characteristic since the gas molecules can easily penetrate into the sensing material to promote the gas reaction on the surface.

In addition to the sensing properties, the selectivity to selectively sense a specific gas is a very important factor in gas sensor performance. Generally, a method of increasing the selectivity is achieved by further bonding the catalytic material to the surface of the metal oxide sensing material. It is known that noble metal catalysts such as platinum (Pt), gold (Au), palladium (Pd), silver (Ag) These noble metal catalysts bind to the surface of the metal oxide and promote the chemical reaction so as to easily react with the decomposition reaction of the gas molecules on the surface and the ionized oxygen adsorbed on the metal oxide surface. Therefore, the role of the catalyst not only promotes the reaction with the gas at the surface of the metal oxide sensing material to exhibit the high sensitivity characteristic, but also serves to enhance the selectivity by promoting the decomposition reaction and the chemical reaction for the specific gas.

As nanotechnology has been rapidly developed, metal oxide gas sensing materials having various nanostructures and surface structures are being developed. Particularly, the conventional micro-particle type metal oxide sensing material has a relatively large particle size and a dense structure between the particles and particles, so that the gas can not easily penetrate into the sensing material, It is difficult to obtain high sensitivity characteristics. In order to overcome such disadvantages, a highly sensitive gas sensing material has been developed using a metal oxide sensing material having a wide surface area and high porosity such as nano-rods, nanofibers, and nanowires using nanotechnology.

In addition to this, control of the optimized structure and dispersity of catalyst materials has led to the development of ultra-sensitive sensing materials that have not been obtained previously, and new application fields are being developed using metal oxide sensing materials. The catalyst material should generally have a miniaturized size of less than 10 nanometers (nm), and at the same time, the catalyst must have a high degree of non-aggregation to activate the chemical reaction through the catalyst on the metal oxide surface. From this point of view, it is necessary to develop a catalyst material of a new method which has not been attempted conventionally, and to develop a technique for uniformly bonding the catalyst to the surface of the metal oxide.

The metal oxide composite gas sensing material having a new type of highly acidic catalytic bonding method and porous structure exhibits an extremely sensitive sensing property and selectivity against chemical gas. Therefore, not only conventionally used hermetic environmental gas sensing sensors, (Biomarker) gas of ppb (part-per-billion) indicating a correlation with diseases contained in the exhalation gas of the gaseous effluent gas.

In the embodiments of the present invention, when a block copolymer in which catalyst particles are uniformly bound is used as a template and the block copolymer to which the synthesized catalyst is bound is subjected to electrospinning using electrospinning technology, A polymer / metal oxide precursor composite nanofiber having a one-dimensional structure in which a block copolymer having a functional group bonded thereto is uniformly bound. In addition, when an additional high-temperature sintering process is performed, a metal oxide nanofiber having a one-dimensional structure can be developed, and a plurality of pores are formed on the surface of the metal oxide having a one-dimensional structure by the block copolymer template, And the catalyst particles are uniformly transferred to the formed pore positions.

Particularly, in the block copolymer in which the catalyst particles are uniformly bound, since the catalyst particles have a size of 10 nm or less, excellent catalytic efficiency can be exhibited when they uniformly bind to the surface of the metal oxide. Also, a spherical block copolymer template having a size range of 50-500 nm is decomposed by heat treatment at a high temperature, and a large number of pores can be formed on the surface of the metal oxide nanofiber. The size of the formed pores is characterized by forming macro pores at 10-300 nm. Characterized in that catalytic particles transferred from the block copolymer are bound to the pore-forming sites, and the catalytic particles are uniformly distributed on the surface of the metal oxide nanofibers as the pores are uniformly formed. Gas sensor application technology is presented.

This is because, in order to solve the problems of the prior art, a nanoparticle catalyst having a very small size of 10 nm or less is bound to the surface of the metal oxide without agglomeration of each other, and at the same time, a porous metal oxide nanofiber structure including a plurality of circular and elliptical pores A gas sensor member capable of detecting an extremely small amount of gas by synthesizing a catalyst using a block copolymer template uniformly bound thereto, a gas sensor using the gas sensor, and a method of manufacturing the same.

In order to solve the above-mentioned problems, a block copolymer template having a size of 10 nm or less is uniformly bound to a block copolymer template according to an aspect of the present invention, and the block copolymer template to which the catalyst is bound is mixed with a metal oxide precursor and a polymer Polymer composite nanofibers having a one-dimensional structure in which a block copolymer template formed by electrospinning and uniformly bound with the catalyst-bound block copolymer is produced, and the metal oxide precursor / The present invention provides a sensing material comprising porous metal oxide nanofibers formed by bonding a catalyst having a one-dimensional structure by removing a polymer component through a heat treatment process and oxidizing a metal oxide precursor, and a method for manufacturing a member for a gas sensor using the same. During the high-temperature heat treatment process, a block copolymer component composed of a polymer is removed, and a plurality of pores are formed on the surface of the metal oxide nanofibers having a one-dimensional structure. The catalyst nanoparticles attached to the surface of the block copolymer have a one- Is transferred to the pore surface formed in the metal oxide nanofiber.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sensing material according to the present invention and a method of manufacturing a member for a gas sensor using the same are manufactured by: (a) synthesizing a block copolymer template in which a catalyst is uniformly bound; (b) preparing an electrospinning solution by mixing the prepared block copolymer template uniformly bound with a metal oxide precursor and a solution in which the polymer is dissolved; (c) forming composite nanofibers in which the prepared catalyst-bound block copolymer template is uniformly distributed on the inside and the surface of the metal oxide precursor / polymer composite nanofiber by electrospinning the electrospin solution; (d) removing the polymer component constituting the block copolymer sacrificial layer template and the composite nanofiber composed of the polymer component during the high-temperature heat treatment process, and oxidizing the metal oxide precursor to form the metal oxide nanofiber having a one- Forming a one-dimensional porous metal oxide nanofiber in which a catalyst is uniformly bound to a pore position while a block copolymer template to which a catalyst is bound is removed, the porous metal oxide nanofiber forming an irregular-shaped concavo-convex structure with pores; (e) dispersing or crushing the one-dimensional porous metal oxide nanofibers prepared through the block copolymer template bound with the catalyst and the sensing material uniformly bound to the catalyst in a plurality of pore positions, Fabricating a resistance variable semiconductor gas sensor using at least one coating process such as drop coating, spin coating, ink jet printing, or dispensing on a sensor electrode; And a method for producing a porous catalyst-metal oxide nanofiber composite sensing material for a gas sensor capable of detecting a biomarker gas for diagnosis of environmentally harmful gases and diseases.

Here, in the step (a), the block copolymer is composed of a polymer material, and a unique structure is formed when different polymer materials are exposed to a specific solvent. When a specific metal salt is further dissolved in the solution, a block copolymer template in which metal particles are uniformly bound due to strong attraction between a metal salt and a specific polymer block can be produced. The block copolymer template in which the metal catalyst particles are uniformly bound may have a spherical structure, and specifically, the portion where the metal catalyst particles are bound is swollen so that the whole structure has a raspberry shape. (II) nitrate, Copper (II) chloride, Cobalt (II) nitrate, Cobalt (II) acetate, Lanthanum (III) nitrate (III) acetate, platinum (IV) chloride, platinum (II) acetate, gold (III) chloride, (II) chloride, nickel (II) acetate, ruthenium (III) chloride, ruthenium acetate, iridium acetate, tantalum (V) chloride and palladium (II) chloride. It does not limit the kind of the special metal salt. The block copolymer template to which the synthesized metal catalyst particles are bound may have a broad size range of 50-500 nm, and the metal particles have a size ranging from 1-10 nm.

The step (b) is a step of preparing an electrospinning solution for progressing electrospinning. The step (b) dissolves the polymer and the metal oxide precursor, which function as a template for effectively synthesizing the nanofibers in the electrospinning process, Can be manufactured. Representative polymers used herein include polymers such as polymethylmethacrylate (PMMA), polyvinylpyrrolidone (PVP), polyvinyl acetate (PVAc), polyvinyl alcohol (PVA), polyacrylonitrile (PAN), polyethylene oxide polypropylene oxide (PEO), polypropylene oxide (PPO), polyethylene oxide copolymer, polypropylene oxide copolymer, polycarbonate (PC), polyvinylchloride (PVC), polycaprolactone And polyvinylidene fluoride. Representative metal salts include metal salts such as acetate, chloride, acetylacetonate, nitrate, methoxide, ethoxide, butoxide, isopropoxide, sulfide, etc. . In addition, the block copolymer template with catalyst particles synthesized in the step (a) may be uniformly dispersed to prepare an electrospinning solution.

In the step (c), the metal oxide precursor / polymer composite nanofibers having a one-dimensional structure in which the block copolymer sacrificial layer template uniformly bound with the metal catalyst particles are uniformly bound to the surface and the interior thereof, .

In the step (d), the polymer constituting the polymer / metal oxide precursor composite nanofibers is decomposed and removed through the high-temperature heat treatment, and at the same time, the block copolymer template having the metal catalyst particles bound thereto is also decomposed and removed at high temperatures. The block copolymer template having a polymer component is characterized in that it forms a large number of pores on the surface and inside of the metal oxide nanofibers having a one-dimensional structure in the process of being decomposed and removed, and on the surface of the block copolymer template And uniformly formed metal catalyst particles are transferred and bound. Here, the size of the pores formed on the surface and inside of the metal oxide nanofibers having a one-dimensional structure is in the range of 10-300 nm.

In the step (e), the dispersion solution obtained by dispersing the porous metal oxide nanofibers having the one-dimensional structure transferred with the catalyst obtained in the step (d) in a solvent is applied to a previously prepared sensor electrode A coating method such as drop coating, spin coating, inkjet printing, dispensing, or the like) on the substrate (e.g., an alumina insulator substrate on which parallel electrodes are formed). Here, if the method is capable of uniformly coating the transferred 1-dimensional porous metal oxide nanofibers with the metal catalyst particles, there is no particular restriction on the coating method.

The 1-dimensional porous metal oxide nanofiber structure to which the fabricated catalyst is transferred may have a length in the range of 1 to 500 μm, and the thickness of the fibers may be in the range of 100 nm to 50 μm And may include circular or elliptical pores.

According to the present invention, by using a block copolymer template in which catalyst nanoparticles are uniformly bound, a plurality of pores are formed in a gas sensing material to be finally produced to activate gas diffusion and reaction, the present invention relates to the development of a porous metal oxide nanofiber sensing material having a one-dimensional structure maximizing the catalytic effect by uniformly transferring catalyst nanoparticles of a size smaller than the nanometer size. The block copolymer template uniformly bound with the synthesized catalyst has a spherical shape, and the catalyst is uniformly bound, and the portion where the catalyst is bound is selectively swollen to have a raspberry shape. . If the block copolymer template with the catalyst thus synthesized is uniformly distributed in the electrospinning solution and the polymer nanofibers prepared by electrospinning are heat treated at a high temperature to remove the polymer component, A plurality of spherical or elliptical pores having a diameter in the range of 10 to 300 nm can be formed by the catalyst particles and the catalyst nanoparticles are uniformly transferred to the positions where the pores are formed, The porous metal oxide nanofiber can be developed.

As mentioned above, by maximizing the sensor characteristics through the shape control of the gas sensor member and the catalytic reaction effect, it has a high sensitivity characteristic capable of detecting a trace amount of gas, and has excellent selectivity for detecting a specific gas, A gas sensor member, and a manufacturing method thereof.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
1 is a schematic view of a member for a one-dimensional porous metal oxide nanofiber gas sensor in which a nanoparticle catalyst according to an embodiment of the present invention is uniformly bonded and includes a plurality of circular or elliptical pores.
FIG. 2 is a graph showing the results of a method of uniformly dispersing a block copolymer template uniformly bound with a catalyst according to an embodiment of the present invention in an electrospinning solution to obtain a block copolymer template having a one- Metal oxide precursor / polymer composite nanofibers are uniformly dispersed on the surface and inside of the metal oxide precursor / polymer composite nanofiber.
FIG. 3 is a cross-sectional view illustrating a method of forming a plurality of pores by using a block copolymer template to which catalysts are bound according to an embodiment of the present invention, forming a one-dimensional porous metal oxide nanofiber structure in which catalyst nanoparticles are uniformly transferred at pore- Fig.
FIG. 4 is a scanning electron microscope (SEM) image of a block copolymer template bonded with spherical and raspberry-like catalyst nanoparticles serving as a sacrificial layer template according to Example 1 of the present invention.
FIG. 5 is a transmission electron microscope photograph of a block copolymer template bonded with spherical and raspberry shaped catalyst nanoparticles serving as a sacrificial layer template according to Example 1 of the present invention.
FIG. 6 is an enlarged transmission electron micrograph of a spherical shape and a raspberry-type catalyst nanoparticle-bound block copolymer template serving as a sacrificial layer template according to Example 1 of the present invention.
FIG. 7 is a graph showing the results obtained by uniformly dispersing a block copolymer template in which platinum (Pt) catalyst nanoparticles are bound to a tungsten oxide precursor / polyvinyl pyrrolidone (PVP) composite spinning solution according to Example 2 of the present invention, And the composite nanofibers formed through the microspheres.
FIG. 8 is a graph showing the results of thermal treatment of a tungsten oxide precursor / polyvinylpyrrolidone composite nanofiber having a uniformly distributed block copolymer template bonded with platinum catalyst nanoparticles according to Example 2 at high temperature, Fig. 3 is a scanning electron micrograph of a porous tungsten oxide nanofiber that is bonded to the surface of the porous tungsten oxide nanofibers.
9 is a graph showing the results of a heat treatment at a high temperature of a tungsten oxide precursor / polyvinyl pyrrolidone composite nanofiber in which a block copolymer template with platinum catalyst nanoparticles bound thereto uniformly distributed according to Example 2 of the present invention, Lt; RTI ID = 0.0 > of < / RTI > porous tungsten oxide nanofibers.
10 is a graph showing the results of a heat treatment at a high temperature of a tungsten oxide precursor / polyvinyl pyrrolidone composite nanofiber in which a block copolymer template having platinum catalyst nanoparticles bound thereto uniformly distributed according to Example 2 of the present invention, Of the porous tungsten oxide nanofiber.
11 is a graph showing the results of a heat treatment at a high temperature of a tungsten oxide precursor / polyvinyl pyrrolidone composite nanofiber in which a block copolymer template having platinum catalyst nanoparticles bound thereto uniformly distributed according to Example 2 of the present invention, FIG. 2 is an enlarged transmission electron micrograph of porous tungsten oxide nanofibers bonded to the surface of the porous support; FIG.
12 is a graph showing the results of thermal treatment of a tungsten oxide precursor / polyvinylpyrrolidone composite nanofiber having a uniformly distributed block copolymer template bonded with platinum catalyst nanoparticles according to an embodiment 2 of the present invention at a high temperature, Of the porous tungsten oxide nanofibers that are bonded to each other by using a transmission electron microscope.
13 is a scanning electron micrograph of a tungsten oxide / polyvinyl pyrrolidone composite nanofiber prepared without using a block copolymer template to which platinum catalyst nanoparticles are bound according to Comparative Example 1 of the present invention.
FIG. 14 is a graph showing the results of the heat treatment of the tungsten oxide / polyvinyl pyrrolidone composite nanofiber fabricated without using the block copolymer template having the platinum catalyst nanoparticles bound thereto according to Comparative Example 1 of the present invention, Scanning electron micrograph of the oxide nanofibers.
Fig. 15 is a graph showing the results of measurement of the surface tension of porous tungsten oxide nanofibers and pure tungsten oxide nanofibers prepared according to Example 1, Example 2, Comparative Example 1 and Experimental Example 1 of the present invention, ppm hydrogen sulfide (H ₂ S) gas.
16 is a graph showing the relationship between the temperature of the porous tungsten oxide nanofibers and the pure tungsten oxide nanofibers, which were prepared according to Example 1, Example 2, Comparative Example 1, and Experimental Example 1, In which the concentration of hydrogen sulfide gas is 5 ppm.
17 is a graph showing the relationship between the amount of hydrogen sulfide and acetone (CH (ppm)) at 5 ppm of the porous tungsten oxide nanofibers and the pure tungsten oxide nanofibers prepared according to Example 1, Example 2, Comparative Example 1, ₃ COCH ₃ ), methylmercaptan (CH ₃ SH), and toluene (C ₆ H ₅ CH ₃ ) gas.
18 is a graph showing the results of principal component analysis using the porous tungsten oxide nanofibers and the pure tungsten oxide nanofibers bonded with the platinum catalyst prepared according to Example 1, Example 2, Comparative Example 1 and Experimental Example 1 of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments will be described in detail below with reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

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

A member for a gas sensor using a one-dimensional porous metal oxide nanofiber structure including a nanoparticle catalyst prepared using a block copolymer template in which catalyst nanoparticles are uniformly bound and having a plurality of spherical and elliptical pores, And a method of manufacturing the same will be described in detail with reference to the accompanying drawings.

A porous metal oxide nanofiber having a one-dimensional structure in which a catalyst prepared after an electrospinning process and a high-temperature heat treatment process are bonded using a sacrificial layer block copolymer template having a catalyst uniformly bound thereto, It is possible to exhibit excellent sensing characteristics with respect to biomarker gas discharged through harmful environmental gas or human exhalation by a plurality of spherical and elliptical pores formed by removing the particle catalyst and block copolymer template. The sacrificial layer block copolymer template in which the catalyst is homogeneously bound dissolves the block copolymer in a specific solvent, so that the different polymer blocks form a regular structure. As typical block copolymers, poly (styrene-b-acrylic acid), poly (styrene-b-ethylene oxide) Poly (styrene-b-4-vinyl pyridine), and poly (styrene-b-dimethylsiloxane), and any one block copolymer or specific molecular weight is not limited as long as it can form a regular structure. By further adding a metal salt thereto, it is possible to form a block copolymer template in which a catalyst salt is selectively bound to one of the polymers, and the metal catalyst particles are uniformly bound naturally without further reduction process. The metal salts include copper (II) nitrate, copper (II) chloride, cobalt (II) nitrate, cobalt (II) acetate, lanthanum (III) nitrate, lanthanum (III) acetate, platinum (II) acetate, Ruthenium (III) chloride, Iron (III) acetate, Nickel (II) acetate, ), chloride, ruthenium acetate, iridium (III) chloride, iridium acetate, tantalum (V) chloride and palladium (II) chloride. If it is a salt, there is no specific restriction. The block copolymer template having the formed catalyst nanoparticles bound thereto has a spherical shape and is characterized by having a raspberry shape that swells up selectively in the process of bonding with the catalyst on the surface. In addition, the block copolymer template having the synthesized catalyst nanoparticles bound thereto may be formed in a range of 50-500 nm in diameter, and the catalyst particles uniformly bound to the block copolymer template surface may have a size of 10 nm or less .

As mentioned above about the influence of the size and distribution of the catalyst particles on the sensing characteristics, in order to maximize the gas sensing characteristic, the smaller the size of the catalyst particle is several nm, and the smaller the aggregation between the catalysts is, the better the catalytic activity reaction is. From this point of view, when the catalyst nanoparticles formed to a size of 10 nm or less and uniformly dispersed on the surface of the block copolymer are transferred to the surface of the metal oxide nanofiber, they can exhibit excellent gas sensing characteristics.

The prepared catalyst nanoparticles-bound block copolymer template may be uniformly dispersed in an electrospinning solution to produce catalyst-porous metal oxide nanofibers having a one-dimensional structure. The electrospinning solution is composed of a metal oxide precursor and a specific polymer, and may be prepared by dissolving it in a specific solvent. The process of homogeneously dispersing the block copolymer template in which the catalyst nanoparticles are bound to the electrospinning mixed solution thus prepared can be further performed. When the electrospinning process is performed using the prepared mixed solution, a metal oxide precursor / polymer composite nanofiber having uniformly distributed block copolymer template with catalyst nanoparticles can be produced. When the composite nanofibers thus produced are thermally treated at a high temperature, the polymer components are decomposed and removed, and the metal oxide precursor is oxidized to form metal oxide nanofibers. In addition, since the block copolymer template having the catalytic nanoparticles bound on the surface and inside of the metal oxide precursor / polymer composite nanofiber is similarly decomposed and removed at high temperature, many pores are formed on the surface and inside of the metal oxide nanofiber . The pores formed can be formed in the range of 10-300 nm, which is a contracted size than the block copolymer template. In addition, the catalyst nanoparticles uniformly bound to the surface of the block copolymer can be transferred to the surface and inside of the metal oxide nanofibers during the high-temperature heat treatment process and can be bound. Thus, the catalyst nanoparticles may characteristically bind at the locations where a plurality of pores are formed. At this time, the bound catalyst is characterized by having a size of 10 nm or less. When the block copolymer template having the catalyst nanoparticles bound thereto is used in the electrospinning process, nanofibers are formed through the electrospinning process without additional pore forming process and catalyst formation process, and the high temperature heat treatment process is performed, The present invention provides an easy production process method capable of producing uniformly bound porous metal oxide nanofibers. A gas sensor member, a gas sensor, and a manufacturing method thereof are implemented in an efficient and easy process for manufacturing a gas sensor member having the above characteristics.

1 is a schematic view of a gas sensor member using a one-dimensional porous nanofiber 100 including a nanoparticle catalyst 103 and circular or elliptical pores 102 according to an embodiment of the present invention . Here, the pores formed on the surface and inside of the metal oxide nanofiber are formed by decomposing a block copolymer template composed of a polymer component in a high-temperature heat treatment process. Since the gas molecules easily penetrate to activate the reaction on the surface, Can be obtained. Also, the catalyst nanoparticles are formed by transferring metal nanoparticles from the block copolymer template to which the catalyst nanoparticles are bound, so that the catalyst particles are uniformly transferred to the positions where the pores are formed. The transferred catalyst nanoparticles can activate the decomposition reaction of the gas when the gas is injected to improve the sensing property and selectivity of the metal oxide sensing material. The porous metal oxide nanofibers having a catalyst-1-dimensional structure have a nanofiber shape composed of metal oxide particles 104 while being crystallized at a high temperature.

The block copolymer template to which the catalyst particles are bound can uniformly bind various kinds of metal catalyst nanoparticles to the surface of the block copolymer depending on the type of the metal salt that is additionally included in the production process. (II) chloride, cobalt (II) nitrate, cobalt (II) acetate, lanthanum (III) nitrate, lanthanum (III) acetate, platinum (II) chloride, Nickel (II) acetate, Ruthenium (III) chloride, Iron (III) acetate, Pd, Rh, Ru, Ni, Co, Cr, Pd, Pd, Pd, Pd, A block copolymer template to which a nanoparticle catalyst such as Ir, Au, Ag, Zn, W, Sn, Sr, In, Pb, Fe, Cu, V, Ta, Sb, Sc, Ti, Mn, Can be synthesized.

FIG. 2 is a diagram illustrating a method of fabricating a one-dimensional porous metal oxide nanofiber in which a nanoparticle catalyst is bound using a block copolymer template prepared as described above. An electrospinning process 200 may be utilized to fabricate the one-dimensional porous metal oxide nanofibers. The electrospinning process begins with the preparation of an electrospinning solution 201 consisting of a metal oxide precursor / polymer. The polymer used in the preparation of the electrospinning solution serves to hold the metal oxide particles, which are formed as a metal oxide precursor under heat treatment at a high temperature, in a nanofiber shape. Typical polymer materials include polymethylmethacrylate (PMMA), polyvinylpyrrolidone (PVP), polyvinyl acetate (PVAc), polyvinyl alcohol (PVA), polystyrene (PS), and polyacrylonitrile (PAN) , Polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), polydianil dimethylammonium chloride (PDADMAC) and polystyrene sulfonate (PSS). Examples of the solvent constituting the electrospinning solution include N, N'-dimethylformamide, dimethylsulfoxide, N, N'-dimethylacetamide (N-methylpyrrolidone), DI water, ethanol, etc., but a solvent capable of simultaneously dissolving the metal oxide precursor and the polymer should be selected.

The block copolymer template 400 having the catalyst nanoparticles bound to the prepared metal oxide precursor / polymer mixed electrospinning solution may further be dispersed. The block copolymer template to which the catalyst nanoparticles are bound can be uniformly mixed and dispersed in the electrospinning solution. Electrospinning is performed using the mixed spinning solution. The electrospinning is carried out in such a manner that the mixed spinning solution is contained in the electrospinning syringe and the high voltage 204 is applied between the electrospinning nozzle 202 and the current collecting plate 203 to uniformly disperse the block copolymer template to which the catalyst nanoparticles are bound The metal oxide precursor / polymer composite nanofibers 300 can be formed. In the formed composite nanofiber, the metal oxide precursor and the polymer may have a uniformly mixed shape 301, and the block copolymer 400 to which the catalyst particles are bound may be uniformly mixed on the surface and inside of the metal oxide precursor / Can be distributed. The catalyst particles (401) bound to the surface of the block copolymer to which the catalyst particles are bound are bound with regular arrangement, and the block copolymer (402) to which the catalyst particles are bound has a spherical shape do. The block copolymer template in the portion to which the catalyst is attached is characterized by having a bulge shape to have a generally raspberry shape. The diameter of the block copolymer template to which the catalyst nanoparticles are bound is in the range of 50-500 nm, and the catalyst particles have a size of 10 nm or less.

The metal oxide precursor / polymer composite nanofiber in which the prepared catalyst particle-bound block copolymer template is uniformly dispersed on the surface and inside is further subjected to a high temperature heat treatment to obtain a porous metal oxide nanofiber having a one- . The metal oxide nanofibers can be made of various materials in accordance with the metal oxide precursor added when preparing the electrospinning solution. More specifically, it is preferable to use 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 , Li ₄ Ti ₅ O ₁₂ , Li ₄ Ti ₅ O ₁₂ , 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, Li 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, Li ₂ MnO ₄ , LiCoO ₂ , LiMn ₂ O ₄ , Ga ₂ O ₃ , LiNiO ₂ , CaCu ₃ Ti ₄ O ₁₂ , Li (Ni, Mn, Co) O ₂ , LiFePO ₄ , Li _4, Li (Mn, Fe) O ₂ , Li _y (Cr _x Mn _{2 -x} ) O _{4 + z} , LiCoMnO ₄ , Ag ₃ PO ₄ , BaTiO ₃ , NiTiO ₃ , SrTiO ₃ , Sr ₂ Nb ₂ O ₇ , Sr ₂ Ta ₂ O _7, Ba _{0 . 5} Sr _{0 . 5} Co _{0 . 8} Fe _{0 . 2} O _{3 -7,} and the like can be produced. The metal oxide nanofibers having a one-dimensional structure in which the prepared catalyst nanoparticles are bound may have a length in the range of 1 μm to 500 μm in the longitudinal direction, and the thickness of the fibers is in the range of 100 nm to 50 μm . Further, the diameter of the pores formed on the surface is in the range of 10-300 nm.

FIG. 3 schematically shows a manufacturing process sequence according to a method of manufacturing a member for a gas sensor using a one-dimensional porous metal oxide semiconductor nanofibers in which a nanoparticle catalyst is uniformly bound by an electrospinning process according to an embodiment of the present invention. . According to the flowchart of FIG. 3, the method for manufacturing a member for a gas sensor comprises the steps of: (S501) preparing a block copolymer template in which a catalyst is uniformly bound, a block copolymer template to which the synthesized nanoparticle catalyst is bound and a metal oxide precursor (S502), the block copolymer template to which the catalyst nanoparticles are bound by electrospinning is uniformly distributed on the surface and inside of the metal oxide precursor / polymer composite nanofiber (S503), synthesizing a one-dimensional porous metal oxide nanofiber structure including a nanoparticle catalyst including a plurality of circular or elliptical pores through a high-temperature heat treatment and uniformly binding to pore sites (S504), and using the porous metal oxide nanofibers to which the catalyst is uniformly transferred, And a step (S505) of manufacturing a gas sensor capable of detecting a bio-indicator gas for disease diagnosis in real time. In addition, the pores formed in the porous metal oxide nanofibers having a one-dimensional structure can form irregular-shaped irregularities on the surface of the metal oxide nanofibers. Each of the above steps will be described in more detail below.

First, a step (S501) of producing a block copolymer template in which a catalyst is uniformly bound is described.

Examples of the block copolymer template used in this step S501 include poly (styrene-b-acrylic acid), poly (styrene-b-ethylene oxide) 2-vinyl pyridine, poly (styrene-b-4-vinyl pyridine), and poly (styrene-b-dimethylsiloxane) may be used. If a block copolymer can form an internal structure among the block copolymers, There is no restriction on merging templates. The block copolymer template may be subjected to a process of dispersing it in a specific solvent. The solvent used herein may be selected from the group consisting of ethanol, water, chloroform, N, N'-dimethylformamide, dimethylsulfoxide, N, N'-dimethyl Compatible solvents such as N, N'-dimethylacetamide, N-methylpyrrolidone and the like can be used. If the block copolymer template can be dispersed, there is no limitation on a specific solvent. In addition, a surfactant may be added to the emulsion, followed by pulverization with an ultrasonic pulverizer to obtain an emulsified solution. In addition, annealing at a high temperature is performed to form a regular structure within the block copolymer to prepare fine particles of polymer. The metal salt precursor is dissolved in a solvent and mixed with fine particles composed of the polymer to form a block copolymer having catalyst particles uniformly bound thereto. The metal salt precursor is selected from the group consisting of copper (II) nitrate, copper (II) chloride, cobalt (II) nitrate, cobalt (II) acetate, lanthanum (III) nitrate, lanthanum (III) acetate, platinum (III) chloride, iron (III) chloride, nickel (II) chloride, nickel (II) acetate, and ruthenium (III) The metal particles formed on the surface of the block copolymer may include Pt, Pd, Rh (I) chloride, Ruthenium Acetate, Iridium (III) chloride, iridium acetate, Tantalum , Ru, Ni, Co, Cr, Ir, Au, Ag, Zn, W, Sn, Sr, In, Pb, Fe, Cu, V, Ta, Sb, Sc, Ti, Mn, . The content of the metal particles bound to the surface of the block copolymer template can be controlled by controlling the content of the metal salt. The molar ratio of the block copolymer to the metal salt to the metal salt may be in the range of 1: 0.001 to 1:10. For example, the block copolymer and the metal salt are preferably maintained in a molar ratio of 1: 1 . When the metal salt precursor and the block copolymer template are mixed and stirred for 24 hours, the metal salt is regularly formed on the surface of the block copolymer as a metal. Additional washing may be performed to remove metal salt ions and impurities that are not participating in the reaction, and the washing process may be carried out using a centrifuge at a rotational speed of 10,000-20,000 rpm for 10-30 minutes. Here, only the block copolymer template to which the catalyst nanoparticles are finally bound is collected and used.

Next, a step (S502) of preparing a metal oxide precursor / polymer mixture spinning solution containing a block copolymer template to which the synthesized nanoparticle catalyst is bound will be described.

In this step (S502), the block copolymer template with the prepared nanoparticle catalyst is added to the metal oxide precursor / polymer mixed solution, so that the block copolymer template colloid bound to the nanoparticle catalyst is uniformly dispersed in the spinning solution And stirred to prepare a mixed spinning solution. Here, the polymer and block copolymer template used in the manufacturing of spinning solution are not limited to specific materials as long as they can be removed during high-temperature heat treatment. Typically, polymethylmethacrylate (PMMA), polyvinylpyrrolidone (PVP ), Polyvinyl acetate (PVAc), polyvinyl alcohol (PVA), polyacrylonitrile (PAN), polyethylene oxide (PEO), polypropylene oxide (PPO), polyethylene oxide copolymer, Polymers such as oxide copolymers, polycarbonate (PC), polyvinylchloride (PVC), polycaprolactone, and polyvinylidene fluoride.

Additionally, the metal oxide precursor used in this step should be dissolved in the solvent during the high-temperature heat _{treatment, 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 , Li ₄ Ti ₅ O ₁₂ , Li ₄ Ti ₅ O ₁₂ , 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, Li 2 MnO 4, LiCoO 2, LiMn 2 O 4, Ga 2 O 3, LiNiO 2 _{, CaCu 3 Ti 4 O 12,} Li (Ni, Mn, Co) O 2, LiFePO 4, Li (Mn, Co, Ni) PO 4, Li (Mn, Fe) O 2, Li y (Cr x Mn 2- _x ) O _{4 + z} , LiCoMnO ₄ , Ag ₃ PO ₄ , BaTiO ₃ , NiTiO ₃ , SrTiO ₃ , Sr ₂ Nb ₂ O ₇ , Sr ₂ Ta ₂ O _7, Ba _{0 . 5} Sr _{0 . 5} Co _{0 . 8} Fe _{0 . 2} O _{3 -7,} and the like, a precursor including a metal oxide nanofiber or a metal salt capable of forming a nanotube, which causes a change in resistance upon adsorption and desorption of a gas, does not limit the specific metal salt.

The ratio by weight of the metal oxide precursor to the polymer for forming the spinning solution is preferably about 1: 1-5, and the ratio of the metal oxide precursor to the nanoparticle catalyst synthesized using the block copolymer template with catalyst nanoparticles is 1 : 0.001-50 is preferable.

In step S502, the process of preparing the mixed electrospinning solution first dissolves the metal oxide precursor in a solvent and disperses the block copolymer template in which the pre-formed nanoparticle catalyst is bound in turn into the solution. Here, as a method of dispersing, there is a method of stirring at a rotation speed of 500 rpm for 1 hour or more. In order to impart viscosity to the prepared solution in order to facilitate electrospinning, the polymer is added at an appropriate ratio and the polymer is sufficiently stirred until dissolved in the solution. The agitation is preferably carried out at room temperature or below at 50 DEG C, and the agitation is carried out for 5 hours to 48 hours with sufficient stirring to uniformly mix the block hollow polymer template with the nanoparticle catalyst attached thereto in the metal oxide precursor and the polymer solution .

The prepared electric discharge mixture solution is electrospun to prepare a metal oxide precursor / polymer composite nanofiber uniformly distributed on the surface and inside of the nanofiber of the block hollow polymer template to which the catalyst nanoparticles are bound (S503) .

In carrying out the step S503, the prepared nanoparticle catalyst is transferred to a syringe which can be filled with the metal oxide precursor / polymer mixed solution containing the block copolymer to which the prepared nanoparticle catalyst is bound, A syringe pump is used to push the syringe at a constant speed to allow a certain amount of spinning fluid to be dispensed. The electrospinning system may include a high voltage generator, a grounded conductive substrate, a syringe, and a syringe nozzle. A high voltage of about 5 kV to about 30 kV is applied between the solution filled in the syringe and the conductive substrate to form an electric field. And the electrification is performed so that the spinning solution discharged through the syringe nozzle is drawn out in a nanofiber form due to the formed electric field. The spinning solution having a long spouting property is obtained by the solid-state polymer fibers obtained by evaporating and volatilizing the solvent contained in the spinning solution, and a block-like structure in which a metal oxide precursor, a polymer and a nanoparticle catalyst are uniformly bound Composite nanofibers in which the template is dispersed are produced. The rate of discharge can be adjusted from about 0.01 ml / min to about 10 ml / min, and a block copolymer template nanofiber with a metal oxide precursor / polymer / Can be produced.

Finally, the prepared composite nanofibers are heat treated at a high temperature to form a plurality of pores on the surface, and a one-dimensional porous metal oxide nanofiber structure in which nanoparticle catalysts are uniformly bonded at the positions where pores are formed is subjected to a step S504 ). ≪ / RTI > Removal of both block copolymers and polymeric materials used as sacrificial layer templates through high temperature heat treatment at 400-800 ° C forms pores of various sizes between 10-300 nm on the surface and inside of the metal oxide nanofibers. In addition, the pores formed in the porous metal oxide nanofibers having a one-dimensional structure can form irregular-shaped irregularities on the surface of the metal oxide nanofibers. In addition, the nanoparticle catalyst bound to the surface of the block copolymer is uniformly bound to the pores formed in the metal oxide nanofibers. In the final structure formed through step S504, a plurality of macroscopic pores are formed on the surface of the metal oxide nanofibers, irregularly shaped irregularities are formed on the surface of the metal oxide nanofibers, and uniformly attached to the nanoparticle catalyst around the formed pores. Dimensional structure of the porous metal oxide nanofibers.

As described above, the catalyst nanoparticles according to the embodiments of the present invention include many circular and elliptic macropores through the electrospinning process using the block copolymer template, and the catalyst nanoparticles A method of fabricating a one-dimensional porous metal oxide nanofibers uniformly bound around pores and fabricating a gas sensor member using porous metal oxide nanofibers having a one-dimensional structure is characterized in that gas easily penetrates through a plurality of pores, And the reaction rate characteristic, the sensitivity characteristic, and the selectivity of the gas sensor can be greatly improved by activating the decomposition reaction of the gas when the gas is introduced by the catalyst nanoparticles uniformly bound to the periphery of the pore .

Hereinafter, the present invention will be described in detail with reference to examples and comparative examples. The examples and comparative examples are merely intended to illustrate the present invention, and the present invention is not limited to the following examples.

Example  1: Platinum (Pt) catalyst nanoparticles Concluded  Block copolymer Template (400) manufacture

In order to synthesize a block copolymer template having platinum catalyst nanoparticles bound thereto, the following synthesis process is performed.

PS-b-P4VP (polymer Sources Inc.) having a total molecular weight (M _n ) of 235 kg / mol and a polydispersity index (PDI) of 1.18 was prepared to prepare a raspberry shaped polymer template containing a platinum catalyst Prepare. A 1 wt% solution of PS-b-P4VP in chloroform was added to 4.5 mL of distilled water containing 1 wt% of a surfactant (pluronic F108 (PEO-b-PPO-b-PEO, 15,000 g / mol, Sigma Aldrich) And emulsified by treatment with a homogenizer at 25,000 rpm for 2 minutes. Distilled water is added to the obtained aqueous emulsion to dilute the organic solvent, and the organic solvent can be reduced in pressure and evaporated using a rotary evaporator at 40 ° C. The resultant was annealed at 95 DEG C for 24 hours to form an internal structure. The dispersion is washed with deionized water and centrifuged (10,000 rpm, 20 minutes) to remove the remaining surfactant, thereby preparing fine particles of polymer.

To prepare microparticles decorated with platinum nanoparticles using the microparticles described above, a platinum precursor (K ₂ PdCl ₄ , Aldrich) solution is added to the microparticle dispersion at a 1: 1 molar ratio based on P4VP units. The mixture is stirred for 24 hours, washed with deionized water, and centrifuged (10,000 rpm, 20 minutes) to purify the polymer fine particles of raspberry type containing platinum catalyst.

4 is a scanning electron micrograph of a block copolymer template bound with platinum catalyst nanoparticles prepared in Example 1. FIG. As can be seen in FIG. 4, it can be seen that a block copolymer template with platinum catalyst nanoparticles bound with spheres of various sizes ranging from 50 to 500 nm can be identified. Platinum catalyst nanoparticles are selectively added to the surface of the P4VP block copolymer It is confirmed that it has a raspberry shape by the shape which swells while being bonded.

FIG. 5 is a transmission electron micrograph of a block copolymer template on which platinum catalyst nanoparticles prepared through Example 1 are bound. The shape of the raspberry of the block copolymer template to which the prepared platinum catalyst particles are bound can be more clearly observed. In FIG. 5, it can be seen that the part where the platinum catalyst is selectively bonded to the surface, and the platinum catalyst is bonded in a regularly dispersed form.

6 is a high-resolution transmission electron micrograph of a block copolymer template bound with platinum catalyst nanoparticles prepared in Example 1. FIG. As can be seen from FIG. 6, it can be confirmed that the platinum catalyst bound to the surface of the block copolymer template has a size of 10 nm or less.

Such a platinum catalyst having a size of several nanometers and uniformly dispersed catalyst nanoparticles can exhibit excellent catalytic activity when they are transferred to the surface of a metal oxide.

Example  2: Platinum (Pt) catalyst nanoparticles Concluded  Block copolymer Template  Production of porous tungsten oxide nanofibers (100) having a one-dimensional structure in which a platinum catalyst was uniformly transferred to pores used

0.25 g of polyvinylpyrrolidone (PVP) (Aldrich) having a molecular weight of 1,300,000 g / mol and 0.2 g of tungsten oxide precursor ammonium metatungstate hydrate (Aldrich) are dissolved in 1.5 g of water. The tungsten oxide precursor / polymer blend solution was placed in a syringe and connected to a syringe pump (Henke-Sass Wolf, 10 ml NORM-JECT), the spinning solution was pushed out at a discharge rate of 0.1 mL / min, A tungsten oxide precursor / polymer composite nanofiber web is prepared by applying a voltage of 14 kV between a needle (25 gauge) to be discharged and a current collecting substrate to obtain a nanofiber web.

The polymer is subjected to a heat treatment at high temperature to remove the tungsten oxide precursor and oxidize the tungsten oxide precursor. The high temperature heat treatment process was performed at 500 ° C. for 1 hour, and the temperature rise and fall temperature was kept constant at 4 ° C./min.

In this way, it is possible to fabricate tungsten oxide nanofibers having a one-dimensional structure by using the electrospinning technique. From the structural point of view, the specific surface area is wide and the gas easily diffuses through the pores formed between the fibers and the fibers, So that it can exhibit excellent sensing characteristics.

Although the metal oxide nanofibers containing tungsten oxide (WO ₃ ) are mentioned as an example in the above embodiments, the metal oxide nanofibers having a one-dimensional structure that can be produced by using electrospinning technology are 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 , Li ₄ Ti ₅ O ₁₂ , Li ₄ Ti ₅ O ₁₂ , 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, Li 2 MnO 4, LiCoO 2, LiMn 2 O 4, Ga 2 O 3, LiNiO 2 _{, CaCu 3 Ti 4 O 12,} Li (Ni, Mn, Co) O 2, LiFePO 4, Li (Mn, Co, Ni) PO 4, Li (Mn, Fe) O 2, Li y (Cr x Mn 2- _x ) O _{4 + z} , LiCoMnO ₄ , Ag ₃ PO ₄ , BaTiO ₃ , NiTiO ₃ , SrTiO ₃ , Sr ₂ Nb ₂ O ₇ , Sr ₂ Ta ₂ O _7, Ba _{0 . 5} Sr _{0 . 5} Co _{0 . 8} Fe _{0 . 2} O _{3 -7} , and the like, and metal oxides composed of one or more of them may be formed.

In order to produce a porous tungsten oxide nanofiber having a one-dimensional structure in which a platinum catalyst is transferred, a block copolymer template having a platinum catalyst attached thereto is further dispersed in the prepared tungsten oxide precursor / polymer composite spinning solution. The content of platinum in the block copolymer template to which the platinum catalyst is bound can be determined by inductive coupled plasma analysis, and the content of platinum used in Example 2 is found to be 312 mg / kg. The content of platinum bound to the surface of the block copolymer template can be controlled by varying the content of the platinum precursor in the process of preparing the block copolymer template to which the platinum catalyst is attached. The metal oxide precursor / polymer spinning solution containing the block copolymer template having the platinum catalyst bound thereto was subjected to electrospinning in the same manner as described above, and the porous tungsten oxide nano-particles having a one-dimensional structure Fibers can be produced.

FIG. 7 is a graph showing the results of the electrospinning of a metal oxide precursor / polymer spinning solution containing a block copolymer template on which a platinum catalyst is bound according to Example 2, and a metal oxide precursor / Scanning electron micrographs of precursor / polymer composite nanofibers. It is confirmed that the block copolymer template to which the platinum catalyst is bound binds to the surface and inside of the composite nanofiber to have a rough surface.

8 is a scanning electron micrograph of a metal oxide precursor / polymer composite nanofiber having a uniformly dispersed block copolymer template bound with a platinum catalyst according to Example 2 after heat treatment at a high temperature. Since the block copolymer template and the polymer were decomposed and removed at high temperature, the tungsten oxide nanofibers of one-dimensional structure were formed, and it was confirmed that many macropores were formed on the surface and inside while the block copolymer template was removed. In addition, it can be confirmed that the pores formed in the tungsten oxide nanofibers form irregular-shaped irregularities on the surfaces of the tungsten oxide nanofibers. In addition, the platinum catalyst nanoparticles bound to the surface of the block copolymer template are selectively and uniformly dispersed in the pore positions of the tungsten oxide having a one-dimensional structure. The heat-treated tungsten oxide nanofibers have a diameter of 300 nm - 2 μm and a length of 1-50 μm.

9 is an enlarged scanning electron micrograph of a porous tungsten oxide nanofiber having a one-dimensional structure to which platinum nanoparticles according to Example 2 are bound. It is possible to confirm a large number of pores formed on the surface of the tungsten oxide nanofiber, and it can be confirmed that the platinum nanoparticles are uniformly bound around the pores.

10 is a transmission electron micrograph of a porous tungsten oxide nanofiber having a one-dimensional structure to which platinum nanoparticles according to Example 2 are bound. 10, it can be seen that a large number of pores are formed not only on the surface but also inside the surface of the tungsten oxide nanofibers by the block copolymer template having the platinum catalyst nanoparticles bound thereto. At the same time, It can be seen that the catalyst particles are uniformly transferred throughout the nanofibers because they are uniformly transferred to the pore positions of the fibers.

11 is a high-resolution transmission electron micrograph of a porous tungsten oxide nanofiber having a one-dimensional structure to which platinum nanoparticles according to Example 2 are bound. As can be seen from FIG. 11, it can be confirmed that the tungsten oxide nanofibers are formed as crystalline oxides after the high-temperature heat treatment through the high-resolution transmission electron microscope. By confirming the platinum crystal lattice, the platinum catalyst can be obtained from the block copolymer template by using the tungsten oxide nanofiber surface . ≪ / RTI >

12 is a photograph of a component analysis using a transmission electron microscope of a porous tungsten oxide nanofiber having a one-dimensional structure in which platinum nanoparticles according to Example 2 are bound. As can be seen from FIG. 12, it can be seen that the porous tungsten oxide nanofibers having a one-dimensional structure in which the prepared platinum nanoparticles are bound are composed of tungsten, oxygen and platinum. Particularly, in the case of platinum catalyst nanoparticles, tungsten oxide nanofibers Therefore, it can be confirmed that they are uniformly distributed.

Comparative Example  1. Platinum (Pt) catalyst nanoparticles Concluded  Block copolymer Template  Manufacture of pure tungsten oxide nanofibers of dense structure without using

Comparative Example 1 is a method for producing pure tungsten oxide nanofibers having a dense structure without using a block copolymer template having platinum (Pt) catalyst nanoparticles bound thereto. In Example 2, a block copolymer The process is the same as the process except that the template is dispersed in the mixed spinning solution.

Specifically, 0.25 g of polyvinylpyrrolidone (PVP) (Aldrich) having a molecular weight of 1,300,000 g / mol and 0.2 g of tungsten oxide precursor ammonium metatungstate hydrate (Aldrich) are dissolved in 1.5 g of water . The tungsten oxide precursor / polymer mixture spinning solution was placed in a syringe and connected to a syringe pump (Henke-Sass Wolf, 10 ml NORM-JECT), the spinning solution was pushed out at a discharge rate of 0.1 mL / min, A tungsten oxide precursor / polymer composite nanofiber web is prepared by applying a voltage of 14 kV between a discharge needle (25 gauge) and a current collector substrate for obtaining a nanofiber web.

The polymer is subjected to a heat treatment at high temperature to remove the tungsten oxide precursor and oxidize the tungsten oxide precursor. The high temperature heat treatment process was performed at 500 ° C. for 1 hour, and the temperature rise and fall temperature was kept constant at 4 ° C./min.

13 is a scanning electron micrograph of a tungsten oxide precursor / polymer composite nanofiber fabricated without using a block copolymer template to which a platinum catalyst is bound according to Comparative Example 1. Fig. It is confirmed that the surface structure is smooth since the block copolymer template to which the platinum catalyst is bound is not used.

14 is a scanning electron micrograph of pure tungsten oxide nanofibers having a dense structure having a dense structure produced after heat treatment of a tungsten oxide precursor / polymer composite nanofiber prepared without using a block copolymer template bound with a platinum catalyst to be. The pores formed on the surface can not be confirmed because the block copolymer template with the platinum catalyst is not used, and the platinum catalyst also exhibits the pure tungsten oxide nanofiber structure without binding. It is confirmed that the pure tungsten oxide nanofibers having a formed one-dimensional structure have a diameter of 300 nm to 2 μm and a length of 1 to 50 μm in the longitudinal direction.

Experimental Example  1. Fabrication and characterization of a gas sensor using porous tungsten oxide nanofibers (100) having a one-dimensional structure in which platinum (Pt) catalysts are uniformly transferred to a plurality of pores and pure tungsten oxide nanofibers having a dense structure

Using the porous tungsten oxide nanofibers sensing material having a one-dimensional structure in which the platinum catalysts prepared in Examples 1 and 2 were bonded, it is possible to detect a harmful gas present in the surrounding environment or a volatile organic An exhalation diagnostic gas sensor for diagnosing a health condition can be manufactured with the concentration of a compound gas (biomarker gas) and its characteristics can be analyzed. Further, as shown in Comparative Example 1, a pure tungsten oxide nanofiber sensing material having a dense structure and its characteristics can be comparatively analyzed.

The platinum catalyst prepared in Examples 1 and 2 and Comparative Example 1 was uniformly transferred to the substrate using a pure tungsten oxide nanofiber sensing material having a dense structure in which the tungsten oxide nanofiber sensing material and the platinum catalyst were not bonded, After sensor fabrication, sensor characterization can be performed. The evaluation of the characteristics of the expiratory sensor was carried out at a relative humidity of 85-95 RH%, which is similar to the gas coming from the mouth of a human, and the concentration of gas was adjusted to 5, 4, and 3 times the hydrogen sulfide (H ₂ S) , 2, and 1 ppm, and the characteristics are evaluated at the sensor operating temperature range of 250 ° C to 450 ° C. The sensitivity of the sensor can be measured by using Agilent's Model 34972A, which measures the resistance of the gas as it flows, and measures the base resistance of the sensor, _gas / R _air resistance change, R _air : resistance in air, R _gas : resistance when flowing the measurement gas).

FIG. 15 is a graph showing the sensing characteristics of a porous tungsten oxide nanofiber sensing material plated with a platinum catalyst and hydrogen sulfide (H ₂ S) gas in a concentration range of 1-5 ppm of dense pure tungsten oxide nanofibers. As can be seen from FIG. 15, it can be confirmed that the sensing performance improved by 32 times or more with respect to the hydrogen sulfide gas concentration of 5 ppm.

FIG. 16 is a graph showing the sensing characteristics of hydrogen peroxide gas at 5 ppm in a driving temperature range of 250 ° C. to 450 ° C. of a porous tungsten oxide nanofiber sensing material bonded with a platinum catalyst and a dense pure tungsten oxide nanofiber. As shown in Fig. 16, it is confirmed that the sensitivity is very good at a driving temperature of 350 DEG C of 834.2 +/- 20.1.

FIG. 17 is a graph showing the sensing characteristics of a porous tungsten oxide nanofiber sensing material bonded with a platinum catalyst and a sensing characteristic at a concentration of 5 ppm of a multi-species gas of a dense structure of pure tungsten oxide nanofibers. As shown in FIG. 17, it exhibits the best detection characteristics for hydrogen sulfide gas and is relatively low for acetone (CH ₃ COCH ₃ ), methylmercaptan (CH ₃ SH), and toluene (C ₆ H ₅ CH ₃ ) And the sensitivity value (R _air / R _gas <25).

18 is a pattern recognition graph through principal component analysis using a porous tungsten oxide nanofiber sensing material plated with a platinum catalyst and pure tungsten oxide nanofibers having a dense structure. As can be seen in FIG. 18, it can be confirmed that various gases can be selectively distinguished by confirming that various kinds of gases clearly recognize pattern recognition in the two-dimensional principal component space.

In the above experimental example, sensor characteristics of a gas sensor sensing material are shown by taking biomaterial gas as an example. However, it is expected that excellent sensor detection characteristics can be expected for H ₂ , NO _x , SO _x , HCHO, and CO ₂ , which are harmful environmental gases. In addition to platinum (Pt) catalyst nanoparticles, It would be possible to manufacture a gas sensor having excellent sensitivity and selectivity for harmful gases other than hydrogen sulfide gas by synthesizing various types of catalyst particles such as Au, Pd, Rh, Cr, Co, do. In addition, by using a porous metal oxide nanofiber sensing material having a one-dimensional structure including many kinds of circular or elliptical pores of various catalyst particles by varying kinds of metal oxide serving as a sensing material matrix, Can be manufactured. The one-dimensional porous metal oxide nanofiber sensing material in which the catalyst is uniformly transferred by using the nanoparticle catalyst bound to the surface of the block copolymer template is excellent in the hazardous environment gas sensor and the health care for analysis and diagnosis of the exhalation volatile organic compound gas It can be used for gas sensors.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art 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 illustrate the present invention. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents thereof should be construed as being included in the scope of the present invention.

Claims (17)

delete delete delete delete delete delete delete delete delete delete delete A method for manufacturing a member for a one-dimensional porous metal oxide nanofiber composite gas sensor,
(a) synthesizing a block copolymer template in which at least one or more metal catalyst particles are uniformly bound;
(b) mixing the block copolymer template with a metal oxide precursor and a solution in which the polymer is dissolved to prepare an electrospinning solution;
(c) forming a metal oxide precursor / polymer composite nanofiber by uniformly dispersing the block copolymer template in the electrospinning solution by electrospinning; And
(d) removing the polymer matrix and the block copolymer template constituting the metal oxide precursor / polymer composite nanofibers through a high-temperature heat treatment process to form spherical pores and irregular-shaped concavo-convex structures on the surface, Forming a one-dimensional porous metal oxide nanofiber in which the metal catalyst particles are uniformly transferred at a position
Dimensional porous metal oxide nanofiber composite gas sensor according to claim 1. 13. The method of claim 12,
The metal catalyst particles in step (a) may be selected from the group consisting of Copper (II) nitrate, Copper (II) chloride, Cobalt (II) nitrate, Cobalt (II) acetate, Lanthanum (III) nitrate, Lanthanum (III) chloride, iron (III) chloride, iron (III) chloride, nickel (II) acetate, ) at least one of the catalyst salts of acetate, Ruthenium (III) chloride, Ruthenium Acetate, Iridium (III) chloride, iridium acetate, Tantalum (V) chloride and Palladium
Wherein the porous metal oxide nanofiber composite gas sensor is a porous metal oxide nanofiber composite gas sensor. 13. The method of claim 12,
The polymer in step (b) may be selected from the group consisting of polymethyl methacrylate (PMMA), polyvinyl pyrrolidone (PVP), polyvinyl acetate (PVAc), polyvinyl alcohol (PVA), polyacrylonitrile Polypropylene oxide (PEO), polypropylene oxide (PPO), polyethylene oxide copolymer, polypropylene oxide copolymer, polycarbonate (PC), polyvinylchloride (PVC), polycaprolactone polycaprolactone), and polyvinylidene fluoride (hereinafter referred to as &quot; polyvinylidene fluoride &quot;
Wherein the porous metal oxide nanofiber composite gas sensor is a porous metal oxide nanofiber composite gas sensor. 13. The method of claim 12,
In the step (c), electrospinning is carried out with a voltage in the range of 5 kV to 30 kV and a spinning liquid discharge speed in the range of 0.01 ml / min to 10 ml / min
Wherein the porous metal oxide nanofiber composite gas sensor is a porous metal oxide nanofiber composite gas sensor. 13. The method of claim 12,
In the step (d), a high-temperature heat treatment is performed in a range of 400 ° C to 800 ° C
Wherein the porous metal oxide nanofiber composite gas sensor is a porous metal oxide nanofiber composite gas sensor. 13. The method of claim 12,
(e) fabricating a resistance variable semiconductor gas sensor using the one-dimensional porous metal oxide nanofiber
Further comprising:
The resistance variable type semiconductor gas sensor is used for a gas sensor capable of detecting an environmentally harmful gas or a biomaterial gas
Wherein the porous metal oxide nanofiber composite gas sensor is a porous metal oxide nanofiber composite gas sensor.

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