KR20210127374A - Gas sensors and member using one-dimensional nanofibers sensitized, and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a gas sensor. More specifically, the gas sensor of the present invention comprises an electrode for measuring the gas sensor, and a one-dimensional porous metal oxide nanofiber to which a metal nanoparticle catalyst is bound to an upper portion of the electrode for measuring the gas sensor. The present invention relates to the high-performance one-dimensional porous metal oxide nanofiber-based gas sensor which maximizes a gas reaction, and a manufacturing method thereof.

Description

One-dimensional porous metal oxide nanofiber-based gas sensor and manufacturing method thereof

The present invention relates to a gas sensor, and more particularly, a one-dimensional nanofiber-based gas sensor showing high sensitivity and high-speed response with high performance using a metal nanoparticle catalyst prepared including a sodium-based halide as a stabilizer, and the same It relates to a manufacturing method.

Among the various gas detection methods, the metal oxide-based resistance-variable gas sensor operates on the simple principle of measuring the resistance change that occurs when a specific target gas molecule is adsorbed and desorbed from the surface. Therefore, a gas sensor system with a simple structure can be built, miniaturization and mass production are easy, and interoperability with other devices is excellent. Because of these advantages, the resistance variable gas sensor is applied to various fields such as air pollutants, toxic gases and narcotics detection sensors, and research for grafting it to wearable devices is being actively conducted.

In order to apply this metal oxide-based gas sensor to industrial fields and daily life, it is a high-sensitivity that can detect even a very small amount of gas, high selectivity that is highly reactive and distinct from other coexisting gases, and a high-speed sensing material that can clearly detect resistance changes within a short time. development is needed The performance of the three main sensors can be improved by maximizing the surface area that can react with oxygen and target gas through the nanostructure of the sensor material. Since a metal oxide semiconductor (MOS) gas sensor operates by a surface chemical reaction, the larger the specific surface area of the sensor structure, the easier the gas reaction on the surface and high reactivity. Among the gas sensor structures that have been made and evaluated so far, nanofibers have advantages such as a large specific surface area and a long aspect ratio, so that almost the entire area of the material can participate in the reaction with the gas. Due to this, the range of resistance change resulting from the formation and disappearance of an electron-depletion layer or depletion layer due to oxygen adsorption and desorption on the sensing material surface increases, resulting in high sensitivity that can detect even a very small amount of gas at a level of several ppm (parts per million). can be obtained

However, if the sensing material is unconditionally made of a nanostructure with a large specific surface area, such as a nanofiber, the gas adsorption is improved regardless of the composition, but it is difficult to clearly separate the resistance change due to only the target gas among various coexisting gases. Therefore, in order to solve this problem, studies are being actively conducted to improve sensitivity and selectivity by binding a metal or metal oxide catalyst to a sensing material.

As a catalyst for improving the performance of a sensing material, not only transition metals such as nickel (Ni) and iron (Fe), but also noble metals such as platinum (Pt), lead (Pd), and gold (Au) are mainly used. In particular, noble metal catalysts are very effective because they induce sensitivity and selectivity improvement through chemical sensitization that increases the concentration of oxygen adsorbing species participating in surface gas reaction, and electronic sensitization in which the oxidation number of the catalyst itself is changed by gas adsorption. However, in order to maximize the sensor performance improvement effect using the catalyst, it is necessary to maximize the contact area with the gas through the nanostructure of the catalyst itself, uniform distribution, and suppression of coarsening caused by agglomeration.

As such, in the case of the metal oxide gas sensor member in the form of a film or agglomerated particles, the thickness of the gimji layer is several hundred nm or more, which makes it difficult for the target gas to reach the inside of the sensing material. do not participate in In addition, when used for a long time at a high temperature of 200° C. or higher, it was difficult to stably drive for a long time because of the coarsening phenomenon caused by the growth of grains of metal oxide and the deterioration of the metal particle catalyst.

Korean Patent Publication No. 10-2014-0123563

In consideration of the above points, the present invention is a method for easily manufacturing a one-dimensional porous metal oxide nanofiber having a very thin thickness using an electrospinning technique in order to maximize the gas reaction, and a metal nanoparticle catalyst using a sodium-based halide , prepare an electrospinning solution in which the metal nanoparticle catalyst, metal precursor, and polymer are dispersed, and oxidatively heat-treat the composite nanofiber synthesized using the electrospinning method to produce a one-dimensional porous metal oxide nanofiber . The high porosity of such one-dimensional porous metal oxide nanofibers facilitates gas in and out through the pores and increases the residence time in the vicinity of the sensing material, thereby promoting gas diffusion and reaction and minimizing inactive points that do not participate in the reaction. An object of the present invention is to provide a one-dimensional porous metal oxide nanofiber-based gas sensor that dramatically increases the surface reaction of the gas and a method for manufacturing the same.

In order to achieve the above object, the one-dimensional porous metal oxide nanofiber-based gas sensor of the present invention comprises an electrode for gas sensor measurement, and one-dimensional porous metal oxide nanofiber on the upper portion for the gas sensor measurement electrode. do.

In the one-dimensional porous metal oxide nanofiber-based gas sensor of the present invention, the gas sensor measurement electrode is hydrogen (H ₂ ), carbon monoxide (CO), acetylene (C ₂ H ₂ ), etc., transformer oil gas, environmental harmful gas and toxic Resistance variable gas that can detect oxidizing gases such as nitrogen dioxide (NO ₂ ), nitrogen monoxide (NO), and reducing gases such as ethanol (C ₂ H ₅ OH), hydrogen sulfide (H ₂ S), and methane (CH _{4 )} It is preferable that it is an electrode for sensor measurement.

In the one-dimensional porous metal oxide nanofiber-based gas sensor of the present invention, the one-dimensional porous metal oxide nanofiber is a metal nanoparticle catalyst formed by mixing a metal catalyst precursor and a sodium-based halide, a metal precursor, and electricity containing a polymer Composite nanofibers formed by electrospinning a spinning solution are one-dimensional porous metal oxide nanofibers in which metal oxide particles are bound by oxidation heat treatment.

The one-dimensional porous metal oxide nanofiber may have a pore size of 50 nm to 100 μm, a thickness of 5 nm to 5 μm, a diameter of 50 nm to 5 μm, and a length of 1 μm to 500 μm.

The one-dimensional porous metal oxide nanofiber is composed of metal oxide particles having a grain size in the range of 1 nm to 40 nm depending on the heat treatment temperature, and an empty space is formed between the metal oxide particles to form a surface of 1 nm to 10 nm. Mesopores with a size of nm are included.

In addition, in order to achieve the above object, the one-dimensional porous metal oxide nanofiber-based gas sensor manufacturing method of the present invention comprises the steps of (a) reacting a metal catalyst precursor with a sodium-based halide to prepare a metal nanoparticle catalyst, (b) preparing an electrospinning solution by dispersing the metal nanoparticle catalyst, a metal precursor, and a polymer in a solvent, (c) preparing a composite nanofiber having a plurality of pores by electrospinning the electrospinning solution , (d) forming a one-dimensional porous metal oxide nanofiber by oxidative heat treatment of the composite nanofiber, and (e) dispersing the one-dimensional porous metal oxide nanofiber in an organic solvent to prepare a nanofiber solution, It may include the step of manufacturing a gas sensor by coating the nanofiber solution on the electrode for gas sensor measurement.

In (a), the metal catalyst precursor is Pt, Pd, Rh, Ru, Ni, Co, Cr, Ir, Au, Ag, Zn, W, Sn, Sr, In, Pb, Fe, Cu, V, Ta, If any one metal salt selected from Sb, Sc, Ti, Mn, Ga, and Ge is included, as long as it is an anionic metal precursor that is soluble in a solvent, there is no great restriction, preferably K ₂ PtCl ₄ , K ₂ PdCl ₄ , H ₂ AuCl ₄ , H ₂ PtCl ₆ , Na ₂ PtCl ₄ , Na ₂ PdCl ₄ , Na ₂ AuCl ₄ , Na ₃ RhCl ₆ , Na ₂ IrCl ₆ Any one selected from the group may be used.

The sodium-based halide is preferably any one selected from sodium iodide (NaI), sodium bromide (NaBr), sodium chloride (NaCl), and sodium fluoride (NaF) as a stabilizer. , most preferably sodium iodide (NaI).

In addition, in the preparation of the metal nanoparticle catalyst in step (a), N,N'-dimethylformamide, dimethyl sulfoxide, N,N'-dimethylacetamide, N-methylpyrrolidone, deionized water, ethanol, tetra The metal catalyst precursor and the sodium-based halide may be reacted using a compatible solvent such as hydrofuran or furfuryl alcohol.

The metal nanoparticle catalyst prepared in step (a) can be obtained through washing and oven drying using centrifugation.

In step (b), if the metal precursor is in the form of any one selected from acetate, chloride, acetylacetonate, nitrate, methoxide, ethoxide, butoxide, isopropoxide, and sulfide containing metal salts Can be used without limitation, more preferably SnCl ₂ , Zn ₄ O(CO ₂ ) ₆ , Zn ₃ O(CO ₂ ) ₆ , Cr ₃ O(CO ₂ ) ₆ , In ₃ O(CO ₂ ) ₆ , Ga ₃ O(CO ₂ ) ₆ , Cu ₂ O(CO ₂ ) ₄ , Zn ₂ O(CO ₂ ) ₄ , Fe ₂ O(CO ₂ ) ₄ , Mo ₂ O(CO ₂ ) ₄ , Cr ₂ O(CO _{2 )} ) ₄ , Co ₂ O(CO ₂ ) ₄ , Ru ₂ O(CO ₂ ) ₄ , Zr ₆ O ₄ (OH ₄ ), Zr ₆ O ₄ (CO ₂ ) ₁₂ , Zr ₆ O ₈ (CO ₂ ) ₈ , In(C ₅ HO ₄ N ₂ ) ₄ , Na(OH) ₂ (SO ₃ ) ₃ , Cu ₂ (CNS) ₄ , Zn(C ₃ H ₃ N ₂ ) ₄ , Ni ₄ (C ₃ H ₃ N ₂ ) ₈ , Zn ₃ O ₃ (CO ₂ ) ₃ , Mg ₃ O ₃ (CO ₂ ) ₃ , Co ₃ O ₃ (CO ₂ ) ₃ , Ni ₃ O ₃ (CO ₂ ) ₃ , Mn ₃ O ₃ (CO ₂ ) ₃ , Fe ₃ O ₃ (CO ₂ ) ₃ , Cu ₃ O ₃ (CO ₂ ) ₃ , Al(OH)(CO ₂ ) ₂ , VO(CO ₂ ) ₂ , Zn(NO ₃ ) ₂ , Zn(O _{2 )} CCH ₃ ), Co(NO ₃ ) ₂ , and Co(O ₂ CCH ₃ ) may be used.

The polymer is polymethyl methacrylate (PMMA), polyvinyl pyrrolidone (PVP), polyvinyl acetate (polyvinyl acetate, PVAc), polyvinyl alcohol (polyvinyl alcohol, PVA), polystyrene ( polystyrene, PS), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), poly acryl acid (PAA), poly diallyldimethylammonium chloride, PDADMAC) and polystyrene sulfonate (polystyrene sulfonate, PSS) may be used.

The solvent is compatible with N,N'-dimethylformamide, dimethyl sulfoxide, N,N'-dimethylacetamide, N-methylpyrrolidone, deionized water, ethanol, tetrahydrofuran, furfuryl alcohol, chloroform Any one selected from among may be used.

In the step (b), the electrospinning solution may be prepared in a weight ratio of 1:0.001 to 1:2 of the polymer and the metal precursor in the electrospinning solution.

The step (c) is a step of manufacturing a composite nanofiber using an electrospinning technique. The solvent evaporates during the electrospinning process, and the metal nanoparticle catalyst and the metal precursor are uniformly distributed inside and on the surface of the nanofiber. It has the form of a membrane.

In step (d), the composite nanofiber may be subjected to oxidation heat treatment by heating the composite nanofiber to a temperature of 400° C. to 1,000° C. at a temperature increase rate of 5° C. per minute to 50° C. per minute.

In step (d), if the oxidative heat treatment process undergoes thermal decomposition, the polymer is removed and the metal precursor is oxidized and crystallized to form crystal grains. In this process, numerous pores are created inside the nanofiber to obtain a one-dimensional porous metal oxide nanofiber. These nanofibers have an open pore structure in the range of 50 nm to 100 μm, and the thickness can be adjusted in the range of 5 nm to 5 μm, diameter 50 nm to 5 μm, and length 1 μm to 500 μm. In addition, it is characterized in that the grain size can be adjusted in the range of 1 nm to 40 nm.

In step (e), the nanofiber solution may be coated on the electrode for gas sensor measurement by using any one coating process selected from drop coating, spin coating, inkjet printing, and dispensing, and the gas sensor in the form of a substrate If there is a method that can uniformly coat the one-dimensional porous metal oxide nanofiber on the electrode for measurement, various coating processes can be applied without any restrictions.

As the organic solvent used when preparing the nanofiber solution in step (e), an alcohol having 1 to 6 carbon atoms (C1 to C6) may be used. For example, methanol, ethanol, propanol, etc. may be used, and ethanol may be preferably used among them.

According to the present invention, the one-dimensional porous metal oxide nanofiber has crystal grains of about 20 nm or less, and has a larger specific surface area and higher gas permeability than a general thin film or particle structure. Therefore, the one-dimensional porous metal oxide nanofiber-based gas sensor maximizes gas diffusion and adsorption and desorption reactions on the nanofiber surface due to the large number of pores and the large specific surface area of the one-dimensional porous metal oxide nanofiber. In addition, the nano-catalyst particles are uniformly bound to the metal oxide nanofiber, and the surface reaction of the gas is remarkably accelerated by chemical sensitization and electronic sensitization effects. Disclosed is a gas sensor member, a gas sensor, and a method for manufacturing the same, which show excellent performance such as high sensitivity, high selectivity, fast reaction/recovery speed, and high stability that can selectively and quickly detect a trace amount of a specific gas from this accelerating effect. have a possible effect.

1 is a flowchart of a one-dimensional porous metal oxide nanofiber-based gas sensor manufacturing method according to an embodiment of the present invention.
2 is a transmission electron microscope and X-ray spectroscopy image of a one-dimensional porous metal oxide nanofiber functionalized with a catalyst according to an embodiment of the present invention.
3 is an X-ray diffraction analysis result of a one-dimensional porous metal oxide nanofiber functionalized with a catalyst according to an embodiment of the present invention.
4 is a graph showing the reaction sensitivity for each temperature to hydrogen gas of a one-dimensional porous metal oxide nanofiber functionalized with a catalyst according to an embodiment of the present invention.
5 is a graph showing a change in resistance to hydrogen gas of a one-dimensional porous metal oxide nanofiber functionalized with a catalyst according to an embodiment of the present invention.

Hereinafter, the one-dimensional porous metal oxide nanofiber-based gas sensor of the present invention will be described in detail with reference to the accompanying drawings, which can be implemented in various different forms by those of ordinary skill in the art to which the present invention pertains as an example. Therefore, it is not limited to what is demonstrated here.

In describing the present invention, if it is determined that a detailed description of a related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

1 is a flowchart of a one-dimensional porous metal oxide nanofiber-based gas sensor manufacturing method according to an embodiment of the present invention. Hereinafter, each of the above steps will be described in more detail.

As shown in FIG. 1, the one-dimensional porous metal oxide nanofiber-based gas sensor manufacturing method is (a) reacting a metal catalyst precursor with a sodium-based halide to prepare a metal nanoparticle catalyst (S110), (b) Preparing an electrospinning solution by dispersing the metal nanoparticle catalyst, a metal precursor, and a polymer in a solvent (S120), (c) electrospinning the electrospinning solution to prepare a composite nanofiber having a plurality of pores (S130), (d) forming one-dimensional porous metal oxide nanofibers by oxidative heat treatment of the composite nanofibers (S140), and (e) dispersing the one-dimensional porous metal oxide nanofibers in an organic solvent to nanofibers Preparing a solution, and coating the nanofiber solution on the electrode for gas sensor measurement may include the step of manufacturing a gas sensor (S150).

First, (a) step (S110) is a step of preparing a metal nanoparticle catalyst by using a sodium-based halide as a stabilizer. Here, the stabilizer is not limited as long as it is a sodium-based halide, which is a halide containing sodium (Na), and includes, for example, NaI, NaBr, NaCl, and the like.

(a) In step (S110), the metal precursor and the sodium-based halide are each dissolved in a separately predetermined solvent, the metal precursor and the sodium-based halide are mixed in an appropriate ratio, respectively, and stirred sufficiently until all are completely dissolved. give. The metal nanoparticle catalyst is prepared while the sodium-based halide and the metal precursor are uniformly mixed by sufficiently stirring at a temperature range of 20°C to 100°C for 1 hour to 24 hours.

Here, as long as it is a metal precursor that is soluble in a solvent, there is no restriction on the material, and as an example of a representative metal precursor, K ₂ PtCl ₄ , K ₂ PdCl ₄ , H ₂ AuCl ₄ , H ₂ PtCl ₆ , Na ₂ PtCl ₄ , Na ₂ PdCl ₄ , Na ₂ AuCl ₄ , Na ₃ RhCl ₆ , Na ₂ IrCl ₆ and the like.

The metal nanoparticle catalyst prepared in this way (a) in step (S110) is recovered by being redispersed in a solvent through centrifugal separation and washing processes. The centrifugation conditions are not limited as long as the particles are precipitated, and the drying temperature is also not limited.

(b) step (S120) is a step of preparing an electrospinning solution for producing nanofibers, and all of the metal nanoparticle catalyst, metal precursor, and polymer prepared through step (a) are mixed in an appropriate ratio in the mixed solution The metal precursor and the polymer are uniformly mixed in the electrospinning solution by sufficiently stirring for 1 hour to 24 hours at a temperature range of 20° C. to 100° C. until dissolved.

Examples of typical metal precursors used at this time are SnCl ₂ , Zn ₄ O(CO ₂ ) ₆ , Zn ₃ O(CO ₂ ) ₆ , Cr ₃ O(CO ₂ ) ₆ , In ₃ O(CO ₂ ) ₆ , Ga ₃ O (CO ₂ ) ₆ , Cu ₂ O(CO ₂ ) ₄ , Zn ₂ O(CO ₂ ) ₄ , Fe ₂ O(CO ₂ ) ₄ , Mo ₂ O(CO ₂ ) ₄ , Cr ₂ O(CO ₂ ) ₄ , Co ₂ O(CO ₂ ) ₄ , Ru ₂ O(CO ₂ ) ₄ , Zr ₆ O ₄ (OH ₄ ), Zr ₆ O ₄ (CO ₂ ) ₁₂ , Zr ₆ O ₈ (CO ₂ ) ₈ , In( C ₅ HO ₄ N ₂ ) ₄ , Na(OH) ₂ (SO ₃ ) ₃ , Cu ₂ (CNS) ₄ , Zn(C ₃ H ₃ N ₂ ) ₄ , Ni ₄ (C ₃ H ₃ N ₂ ) ₈ , Zn ₃ O ₃ (CO ₂ ) ₃ , Mg ₃ O ₃ (CO ₂ ) ₃ , Co ₃ O ₃ (CO ₂ ) ₃ , Ni ₃ O ₃ (CO ₂ ) ₃ , Mn ₃ O ₃ (CO ₂ ) ₃ , Fe ₃ O ₃ (CO ₂ ) ₃ , Cu ₃ O ₃ (CO ₂ ) ₃ , Al(OH)(CO ₂ ) ₂ , VO(CO ₂ ) ₂ , Zn(NO ₃ ) ₂ , Zn(O ₂ CCH _{3 )} ), Co(NO ₃ ) ₂ , Co(O ₂ CCH ₃ ), and the like.

(c) In step (S130), the electrospinning solution prepared in (b) step (S120) is used in the electrospinning method to prepare a composite nanofiber. After filling a syringe with the electrospinning solution in which the metal nanoparticle catalyst, the metal precursor, and the polymer are dispersed, a predetermined amount is discharged. The electrospinning system includes a high voltage device, a grounded conductive substrate, a syringe, and a syringe nozzle. When an electric field of about 5 kV to 30 kV is applied between the solution filled in the syringe and the conductive substrate, the discharged spinning solution is obtained on the conductive substrate. The discharge amount can be adjusted in the range of 0.01ml/min to 1.0ml/min, and a one-dimensional composite nanofiber felt having a desired diameter and thickness can be manufactured by controlling the voltage and the discharge amount.

(d) In step (S140), a one-dimensional porous metal oxide nanofiber is prepared. When the composite nanofiber obtained in step (c) (S130) is subjected to oxidation heat treatment at 400° C. to 1,000° C., the polymer is thermally decomposed, and the metal precursor becomes a metal oxide. In particular, as the polymer is thermally decomposed and removed, the nanofiber contains many pores therein, thereby forming a one-dimensional porous metal oxide nanofiber to which a metal nanoparticle catalyst is bound.

(E) step (S150) may further include the step of dispersing the one-dimensional porous metal oxide nanofibers in an organic solvent and coating them on the electrode for gas sensor measurement. In this step, a dispersion solution is prepared by uniformly and stably dispersing a one-dimensional porous metal oxide nanofiber to which a metal nanoparticle catalyst is bound in an organic solvent, and the prepared dispersion solution is prepared in advance.

It is coated on an alumina insulator substrate on which an electrode for gas sensor measurement or a parallel electrode capable of measuring electrical conductivity and electrical resistance is formed using a coating process such as drop coating, spin coating, inkjet printing, or dispensing.

Hereinafter, the manufacturing method and characteristics of the one-dimensional porous metal oxide nanofiber-based gas sensor will be described in more detail through Examples and Experimental Examples.

Example 1: Preparation of metal nanoparticle catalyst using sodium iodide (NaI) as a stabilizer

Completely dissolve 190 mg _{of K 2} PdCl _{4 in} 10 ml of dimethylformamide (DMF). In addition, 0.1125 g of sodium iodide (NaI) is dissolved in 5 ml of dimethylformamide (DMF) separately. After that, the mixed solution of the two solutions is stirred at 350 rpm for 30 minutes or more. The mixed solution is transferred to the Teflon-treated reactor, sealed with an autoclave, and reacted at 200°C for 5 hours at a temperature increase rate of 5°C per minute. After completion of the reaction, the formed nanoparticles are recovered through centrifugation and washing processes.

Example 2: One-dimensional porous Pd-SnO ₂ Nanofiber Fabrication

In Example 2, a one-dimensional porous Pd-SnO ₂ nanofiber was prepared as a one-dimensional porous metal oxide nanofiber.

First, dimethylformamide (DMF) 1.35g, ethanol 1.35g, SnCl ₂ ·2H ₂ O 0.25g, polyvinylpyrrolidone (PVP, molecular weight 1,300,000 g / mol) 0.35g, the mixed solution synthesized in Example 1 The catalyst particles are added and dissolved by stirring at a rotation speed of 250 rpm for 6 hours or more. At this time, the ratio of the catalyst may be adjusted in the range of 0.00001 wt% to 1 wt%. The prepared electrospinning solution is placed in a syringe (Henke-Sass Wolf, 12ml NORM-JECT®) and electrospinning is performed (discharge rate: 0.01~1.0ml/min, nozzle: 21~25 gauge, voltage: 5~30kV) Composite nanofibers are prepared.

The composite nanofibers prepared by the above method were heat-treated at 600° C. for 1 hour at a temperature increase rate of 5° C./min, and then cooled to room temperature at a descending rate of 40° C./min. In this process, the polymer in the one-dimensional composite nanofiber is thermally decomposed to form pores, and the metal precursor is oxidized to a metal oxide. As a result, a one-dimensional porous PdO-SnO ₂ nanofiber structure is formed.

2 is a transmission electron microscope and X-ray spectroscopy images of the one _{-dimensional porous PdO-SnO 2} nanofibers synthesized in Examples 1 and 2 above. The nanofiber structure and well-dispersed Pd, Sn, and O can be seen.

3 is an X-ray diffraction analysis result of the one-dimensional porous PdO-SnO _{2 nanofibers synthesized in Examples 1 and 2 above.} The PdO pattern was not observed, and it can be confirmed that the _{SnO 2 nanofiber was well formed.}

Experimental Example 1: Gas sensor manufacturing and characteristic evaluation using one-dimensional porous PdO-SnO _{2 nanofibers}

A dispersion solution was prepared by dispersing 5 mg of the one-dimensional porous PdO-SnO _{2 nanofibers prepared in Examples 1 and 2 above in 300 μl of ethanol, respectively. 2.5} μl of this dispersion solution is drop-coated twice on an alumina (Al 2 O ₃ ) substrate (parallel gold (Au) electrode spacing: 150 μm) having a size of 3 mm × 3 mm. The sensor characteristics evaluation is carried out with the gas sensor manufactured in this way. In this Experimental Example 1, characteristic evaluation was performed on hydrogen, which is a colorless, odorless, and tasteless combustible gas at room temperature.

4 is a graph showing hydrogen sensitivity by temperature evaluated by coating the one _{-dimensional porous PdO-SnO 2} nanofibers synthesized in Examples 1 and 2 according to Experimental Example 1. FIG. Here, the hydrogen sensitivity was defined as the value obtained by dividing the reference resistance at the time of air inflow by the resistance at the time of gas inflow. Performance evaluation was performed on four or more sensor arrays and the average value of the sensitivity was plotted. In this case, the error bar represents the standard deviation of these arrays. As shown in FIG. 4 , a sensitivity of about 6.7 is exhibited at 300° C. for 5 ppm hydrogen.

5 is a graph showing a change in resistance to 5 ppm hydrogen gas of _{one-dimensional porous PdO-SnO 2} nanofibers synthesized through Examples 1 and 2 and coated according to Experimental Example 1. FIG. It can be seen that the resistance decreases when 5 ppm hydrogen gas is injected after stabilization in air. This is because the surface oxygen adsorbing species releases free electrons that were bound while being desorbed by hydrogen, which is a reducing gas, thereby reducing the thickness of the electron-deficient layer. When exposed to air again, the resistance increases as oxygen is adsorbed back to the sensing material surface. In this way, when hydrogen and air are alternately injected into the enclosed space where the sensing material is placed, the resistance increases and decreases repeatedly. The one-dimensional porous nanofiber structure can facilitate gas diffusion due to its large specific surface area and large porosity, and the surface reaction is further promoted by the catalyst, thus showing much improved sensing properties.

The one-dimensional porous metal oxide nanofiber-based gas sensor of the present invention as described above can synthesize ultra-small catalyst nanoparticles of several nm in a simple one-pot method by using a sodium-based halide as a stabilizer, The synthesized primary porous metal oxide nanofibers functionalized with metal nanoparticle catalysts increase the surface reaction of gases based on a long aspect ratio, a large specific surface area and porosity, and a high active catalytic reaction point. Accordingly, there is an effect that can be applied to an effective gas sensor member, a gas sensor, and a method for manufacturing the same, showing high sensitivity characteristics capable of detecting a very small amount of gas with very high sensitivity.

Claims (15)

electrode for gas sensor measurement; and
One-dimensional porous metal oxide nanofiber-based gas sensor comprising a; one-dimensional porous metal oxide nanofiber on the upper portion for the electrode for measuring the gas sensor. According to claim 1,
The one-dimensional porous metal oxide nanofiber,
A metal nanoparticle catalyst formed by mixing a metal catalyst precursor and a sodium-based halide, a metal precursor, and a composite nanofiber formed by electrospinning an electrospinning solution containing a polymer is oxidatively heat treated to form a one-dimensional porous metal to which metal oxide particles are bound One-dimensional porous metal oxide nanofiber-based gas sensor, characterized in that it is an oxide nanofiber. According to claim 1,
The one-dimensional porous metal oxide nanofiber is a one-dimensional porous metal oxide nanofiber-based gas sensor, characterized in that the pore size is 50nm to 100㎛. According to claim 1,
The one-dimensional porous metal oxide nanofiber has a thickness of 5 nm to 5 μm, a diameter of 50 nm to 5 μm, and a length of 1 μm to 500 μm. According to claim 1,
The one-dimensional porous metal oxide nanofiber-based gas sensor, characterized in that the size of the crystal grains in the metal oxide particles is 1 ㎚ to 40 ㎚. (a) preparing a metal nanoparticle catalyst by reacting a metal catalyst precursor with a sodium-based halide;
(b) dispersing the metal nanoparticle catalyst, the metal precursor, and the polymer in a solvent to prepare an electrospinning solution;
(c) preparing a composite nanofiber having a plurality of pores by electrospinning the electrospinning solution;
(d) forming a one-dimensional porous metal oxide nanofiber by oxidative heat treatment of the composite nanofiber; and
(e) preparing a nanofiber solution by dispersing the one-dimensional porous metal oxide nanofiber in an organic solvent, and coating the nanofiber solution on an electrode for gas sensor measurement to prepare a gas sensor; A one-dimensional porous metal oxide nanofiber-based gas sensor manufacturing method. 7. The method of claim 6,
The metal catalyst precursor is K ₂ PtCl ₄ , K ₂ PdCl ₄ , H ₂ AuCl ₄ , H ₂ PtCl ₆ , Na ₂ PtCl ₄ , Na ₂ PdCl ₄ , Na ₂ AuCl ₄ , Na ₃ RhCl ₆ , and Na ₂ IrCl _{6 ,} One-dimensional porous metal oxide nanofiber-based gas sensor manufacturing method comprising any one metal salt selected from. 7. The method of claim 6,
The sodium-based halide is one-dimensional porous metal oxide nano, characterized in that any one selected from sodium iodide (NaI), sodium bromide (NaBr), sodium chloride (NaCl), and sodium fluoride (NaF) A method for manufacturing a fiber-based gas sensor. 7. The method of claim 6,
The metal precursor is SnCl ₂ , Zn ₄ O(CO ₂ ) ₆ , Zn ₃ O(CO ₂ ) ₆ , Cr ₃ O(CO ₂ ) ₆ , In ₃ O(CO ₂ ) ₆ , Ga ₃ O(CO ₂ ) ₆ , Cu ₂ O(CO ₂ ) ₄ , Zn ₂ O(CO ₂ ) ₄ , Fe ₂ O(CO ₂ ) ₄ , Mo ₂ O(CO ₂ ) ₄ , Cr ₂ O(CO ₂ ) ₄ , Co ₂ O (CO ₂ ) ₄ , Ru ₂ O(CO ₂ ) ₄ , Zr ₆ O ₄ (OH ₄ ), Zr ₆ O ₄ (CO ₂ ) ₁₂ , Zr ₆ O ₈ (CO ₂ ) ₈ , In(C ₅ HO _{4 )} N ₂ ) ₄ , Na(OH) ₂ (SO ₃ ) ₃ , Cu ₂ (CNS) ₄ , Zn(C ₃ H ₃ N ₂ ) ₄ , Ni ₄ (C ₃ H ₃ N ₂ ) ₈ , Zn ₃ O ₃ (CO ₂ ) ₃ , Mg ₃ O ₃ (CO ₂ ) ₃ , Co ₃ O ₃ (CO ₂ ) ₃ , Ni ₃ O ₃ (CO ₂ ) ₃ , Mn ₃ O ₃ (CO ₂ ) ₃ , Fe ₃ O ₃ (CO ₂ ) ₃ , Cu ₃ O ₃ (CO ₂ ) ₃ , Al(OH)(CO ₂ ) ₂ , VO(CO ₂ ) ₂ , Zn(NO ₃ ) ₂ , Zn(O ₂ CCH ₃ ), Co( NO ₃ ) ₂ , and Co(O ₂ CCH ₃ ) One-dimensional porous metal oxide nanofiber-based gas sensor manufacturing method, characterized in that at least one selected from the group consisting of. 7. The method of claim 6,
The polymer is polymethyl methacrylate, polyvinyl pyrrolidone, polyvinyl acetate, polyvinyl alcohol, polystyrene, polyacrylonitrile ( polyacrylonitrile), polyvinylidene fluoride, polyacryl acid, poly diallyldimethylammonium chloride, and polystyrene sulfonate A one-dimensional porous metal oxide nanofiber-based gas sensor manufacturing method. 7. The method of claim 6,
The solvent is any one selected from N,N'-dimethylformamide, dimethyl sulfoxide, N,N'-dimethylacetamide, N-methylpyrrolidone, deionized water, ethanol, tetrahydrofuran, furfuryl alcohol, and chloroform One-dimensional porous metal oxide nanofiber-based gas sensor manufacturing method, characterized in that. 7. The method of claim 6,
Step (b) is,
One-dimensional porous metal oxide nanofiber-based gas sensor manufacturing method, characterized in that the electrospinning solution is prepared in a weight ratio of 1:0.001 to 1:2 of the polymer and the metal precursor in the electrospinning solution. 7. The method of claim 6,
Step (d) is,
One-dimensional porous metal oxide nanofiber-based gas sensor manufacturing method, characterized in that the oxidative heat treatment of the composite nanofiber at a temperature of 400 ℃ to 1,000 ℃. 7. The method of claim 6,
Step (d) is,
One-dimensional porous metal oxide nanofiber-based gas sensor manufacturing method, characterized in that the composite nanofiber is heated at a temperature increase rate of 5°C per minute to 50°C per minute. 7. The method of claim 6,
Step (e) is,
One-dimensional porous metal oxide nanofiber-based gas sensor manufacturing, characterized in that the nanofiber solution is coated on the electrode for gas sensor measurement using any one coating process selected from drop coating, spin coating, inkjet printing, and dispensing Way.

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