A preparation method and application of CDs / Au / ZnO gas sensitive sensing material

Abstract

The invention discloses a preparation method and application of a CDs / Au / ZnO gas-sensitive sensing material. The specific preparation process is: using CDs as a reducing agent to obtain precursor Au nanoparticles in a green, pollution-free and simple method, and then combining with zinc acetate by a one-pot hydrothermal method to obtain a CDs / Au / Zn5(CO3)2(OH)6 precursor, and then calcining for 2 hours in a high-temperature inert atmosphere at 500°C to obtain a CDs / Au / ZnO gas-sensitive sensing material, and applying the CDs / Au / ZnO gas-sensitive sensing material to an alumina ceramic tube containing a gold electrode to make a gas sensor for the detection of acetone gas. The preparation method of the invention is simple, the manufacturing cost is low, and high response, high selectivity, and rapid response and recovery to acetone gas can be achieved, and low-concentration acetone detection can be achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation and application of precious metal modified semiconductor metal oxide nanomaterials, and specifically relates to a method for preparing a CDs / Au / ZnO gas sensitive sensor material and application thereof in preparing an acetone gas sensor. Background Art

[0002] In recent years, explosive and toxic volatile organic compounds, such as ethanol, acetone, isopropanol, acetaldehyde, formaldehyde, etc., have posed an increasingly serious threat to people's health, the transportation industry and the ecological environment. There is an urgent need for simple and effective detection methods. Gas sensors, as a device for detecting gas, can effectively detect gas types and concentrations. Among them, gas sensors based on semiconductor metal oxides have the advantages of small size, high stability, easy operation, and low manufacturing cost, and have been widely studied worldwide.

[0003] Among the many conductive metal oxides, ZnO is a typical n-type semiconductor and is considered to be one of the main sensing materials for detecting acetone. However, ZnO still has disadvantages in detecting acetone, such as low response, slow response and slow response recovery, poor selectivity, and it is very difficult to accurately analyze low-concentration acetone. Therefore, it is necessary to design and develop an acetone gas sensor with high response and selectivity based on ZnO. In general, modifying noble metals is an effective method to significantly improve the sensing performance of gas-sensitive sensing materials, which is due to the excellent catalytic activity of noble metals that improves the sensing performance of semiconductor metal oxides, or directly improving the surface properties of semiconductor metal oxides through the electronic interaction of noble metals.

[0004] Among the numerous gas-sensitive sensing materials of semiconductor metal oxides modified with precious metals, Au is regarded as an effective catalyst that can significantly improve the sensing performance in detecting target gas molecules. To obtain semiconductor metal oxides modified with Au, reducing agents such as ascorbic acid and sodium citrate are generally used to obtain precursor Au nanoparticles. However, in recent years, as people pay more and more attention to green and environmental protection, the use of green and low-toxic carbon dots to reduce precious metals has received widespread attention. At present, many literatures have reported examples of carbon dots reducing precious metals. For example, Liu et al. (Journal of Colloid and Interface Science, 555, (2019), 423-430) used CQDs containing some oxygen-containing groups to in situ reduce Pd(II), and the obtained CQDs@Pd nanoclusters can be used to enhance the catalytic reduction of aromatic nitro compounds by SnS2; Li et al. (Biosensors and Bioelectronics, 87, (2017), 772-778) used carbon dots synthesized by ethylene glycol to reduce HAuCl4 to prepare Au nanoparticles / carbon quantum dot complexes, and combined the advantages of fluorescence and colorimetry to detect arginine using a two-dimensional optical sensing platform; for example, Nguyen et al. (Journal of The Electrochemical Society, 168, (2021), 044509) used straw-derived carbon dots as direct reductants and stabilizers to synthesize Au / Cdot nanohybrid electrocatalysts to improve hydrogen evolution reaction. It can be seen that carbon dots have great application potential in reducing precious metals. However, the application of carbon dots to reduce gold particles for gas sensing has not been reported. Therefore, the present invention attempts to use carbon dots (CDs) as a reducing agent, and then use the reduced Au nanoparticles to modify ZnO to prepare a CDs / Au / ZnO nanofunctional material, and study its gas-sensitive properties, which has important theoretical and experimental significance. This material is expected to become a very promising gas sensing material, and this synthesis method also provides a new universal strategy for efficient sensitive materials. Summary of the invention

[0005] The technical problem solved by the present invention is to provide a method for preparing a green, pollution-free and low-manufacturing-cost CDs / Au / ZnO gas-sensitive sensing material. The CDs / Au / ZnO gas-sensitive sensing material prepared by the method can be used to prepare an acetone gas sensor and can achieve high-performance detection of acetone gas.

[0006] The present invention adopts the following technical scheme to solve the above technical problems. A method for preparing a CDs / Au / ZnO gas-sensitive sensor material is characterized in that the specific process is: using CDs as a reducing agent to reduce HAuCl4 to obtain a precursor Au nanoparticle, then using a one-pot hydrothermal method to combine with zinc acetate to obtain a CDs / Au / Zn5(CO3)2(OH)6 precursor, and then calcining at 500°C for 2h in an inert atmosphere to obtain a CDs / Au / ZnO gas-sensitive sensor material. The CDs / Au / ZnO gas-sensitive sensor material The CDs / Au nanoparticles are evenly distributed on the ZnO nanorods, wherein the length of the ZnO nanorods is 35-70 nm, the particle size of the CDs / Au nanoparticles is 18-20 nm, and the CDs / Au nanoparticles are in a monodisperse state. The CDs / Au / ZnO gas-sensitive sensing material is applied to an alumina ceramic tube containing a gold electrode to make a gas sensor for selectively detecting acetone gas, thereby achieving high response, high selectivity, rapid response and recovery to acetone gas, and can also detect low-concentration acetone gas.

[0007] The method for preparing the CDs / Au / ZnO gas sensitive sensor material of the present invention is characterized by the following specific steps:

[0008] Step S1: Preparation of solid CDs: 0.5-1 g of citric acid was dissolved in 5-10 mL of deionized water, and then 300-350 μL of ethylenediamine was added. The mixed solution was transferred to a high-pressure reactor and kept at 180° C. for 8-10 hours. After the high-pressure reactor was naturally cooled to room temperature, the obtained solution was dialyzed with a dialysis bag for 3-5 days, and then filtered with a 0.22 μm filter membrane. The filtrate was then dried in an oven at 100° C. for 10-12 hours to finally obtain solid CDs with reducing properties.

[0009] Step S2: Preparation of precursor Au nanoparticles. The solid CDs obtained in step S1 are dispersed in deionized water to obtain a CDs solution with a concentration of 0.5 mg / mL. 7-10 mL of the CDs solution with a concentration of 0.5 mg / mL is taken, 1-2 mL of a 0.02 M sodium hydroxide solution is added, and after mixing evenly, 0.005 mmol of HAuCl4 solution is added dropwise. After the mixed solution is reacted at room temperature for 4-10 hours, the color of the solution turns purple-red, thereby obtaining a CDs / Au precursor solution reduced by CDs;

[0010] Step S3: Preparation of CDs / Au / ZnO gas sensitive sensing material, take 1mmol of zinc acetate and dissolve it in 20~30mL deionized water, then add the CDs / Au precursor solution prepared in step S2 to the zinc acetate solution, continue to add dropwise 20~30mL of an aqueous solution composed of 1.4mmol anhydrous sodium sulfate and 2mmol anhydrous sodium carbonate, stir for 20~30min, transfer the mixed solution to a high pressure reactor, and then place it in an oven at 180°C for 2~3h, wait for the high pressure reactor to cool naturally to room temperature, collect the bottom precipitate by centrifugation, wash it with deionized water and anhydrous ethanol several times, and then place it in a vacuum drying oven at 60°C for 5~6h, and finally calcine it at 500°C for 2~5h in a N2 atmosphere to obtain CDs / Au / ZnO gas sensitive sensing material.

[0011] The application of the CDs / Au / ZnO gas-sensitive sensing material in an acetone gas sensor of the present invention is characterized in that the CDs / Au / ZnO gas-sensitive sensing material is applied to an alumina ceramic tube containing a gold electrode, and the resulting gas sensor can be used to selectively detect acetone gas.

[0012] The CDs / Au / ZnO gas-sensitive sensing material of the present invention is used to prepare a gas sensor, which is applied to the detection of acetone gas. The specific preparation process of the acetone gas sensor is as follows: a small amount of the prepared CDs / Au / ZnO gas-sensitive sensing material is placed in a mortar, an appropriate amount of ethanol solution is added, and then it is continuously ground to obtain a paste; a certain amount of the paste is dipped with a brush and evenly applied to an alumina ceramic tube with gold electrodes at both ends, and placed in a 60°C oven for drying; a nickel-chromium heating wire is used as a heater, and the working temperature is controlled by adjusting the heating voltage; then the ceramic tube containing the nickel-chromium heating wire is welded to a high-temperature resistant base; finally, the prepared gas-sensitive sensor is aged at 350°C for 48 to 96 hours, and a gas sensor with the CDs / Au / ZnO gas-sensitive sensing material as a sensing layer is obtained, which can realize the detection of acetone gas, and the acetone gas sensor has good selectivity, high response, and response / recovery to acetone gas.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] 1. The present invention provides a novel preparation method to obtain a zinc oxide sensor material modified with precious metal gold nanoparticles, using cheap and easy-to-prepare CDs to reduce Au nanoparticles at room temperature, then reacting the obtained CDs / Au with a zinc acetate precursor under hydrothermal conditions, and finally calcining to obtain a CDs / Au / ZnO gas-sensitive sensor material. The preparation method has few steps, simple operation, and is green and pollution-free.

[0015] 2. The CDs / Au / ZnO gas-sensitive sensing material prepared by the present invention has the following structural characteristics: the size of Au nanoparticles reduced by CDs is about 18-20 nm and is in a monodisperse state. After hydrothermal calcination, the CDs / Au nanoparticles are uniformly distributed on the ZnO nanorods, wherein the length of the ZnO nanorods is 35-70 nm. Therefore, when CDs / Au is evenly dispersed between the ZnO nanorods, the synergistic effect of CDs and Au nanoparticles can significantly improve the gas-sensitive performance of the ZnO nanorods to acetone gas.

[0016] 3. The CDs / Au / ZnO gas-sensitive sensing material prepared by the present invention effectively improves the response sensitivity and selectivity to acetone gas compared with pure ZnO. The response to 100ppm acetone at an operating temperature of 310°C can reach 185.9, and the response and recovery time are 7s and 23s respectively. It still responds to ppb-level acetone, realizing the detection of low-concentration acetone. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a TEM image of the CDs / Au / ZnO gas-sensitive sensor material prepared in Example 1, where the inset is a TEM image of CDs / Au. It can be seen from the figure that the Au nanoparticles reduced by CDs have a size of about 18-20 nm and are monodispersed. After hydrothermal calcination, a gas-sensitive sensor material in which CDs / Au is uniformly distributed on the nanorod ZnO is obtained, wherein the length of the ZnO nanorod is 35-70 nm.

[0018] Figure 2 Schematic diagram of a sensor prepared by applying the gas sensitive sensing material prepared in Example 1 on an alumina ceramic tube. Figure 2 It can be seen that the sensor manufactured in Example 1 is composed of the following parts: a platinum wire 1, a CDs / Au / ZnO gas sensitive sensing material sensing layer 2, a nickel-chromium heating wire 3, a gold electrode 4, an alumina ceramic tube 5 and a high temperature resistant base 6.

[0019] Figure 3 The following is a graph showing the selective response sensitivity of the sensors made in Examples 1, 2, 3 and Example 1 to 100 ppm acetone test gas. Figure 3As shown, the sensors of Comparative Examples 1, 2, 3 and Example 1 were tested at 310°C for 100ppm methanol, acetic acid, ethanol, ammonia, toluene, acetone, ethyl acetate, acetaldehyde, dichloromethane, formaldehyde and cyclohexane. By comparing the test results, it was found that Example 1 showed excellent selectivity for acetone, and the response value reached 185.9 at the highest, which was better than Comparative Examples 1, 2 and 3. By comparing Comparative Example 1 with Comparative Example 2 or Comparative Example 3 with Example 1, it was found that the response sensitivity of CDs / ZnO and CDs / Au / ZnO gas-sensitive sensing materials to acetone was higher than that of ZnO and Au / ZnO gas-sensitive sensing materials without CDs, indicating that CDs has a certain effect on improving the gas-sensitive performance of ZnO. The above results confirm that the acetone sensor made in Example 1 can achieve high response and high selectivity to acetone gas.

[0020] Figure 4 is the response sensitivity curve of the sensor made in Example 1 to low concentration acetone, such as Figure 4 As shown, the sensor produced in Example 1 still has a high response to the ppb level acetone test gas at the optimal operating temperature of 310°C, indicating that the sensor produced in Example 1 can accurately analyze low concentration acetone and show a good linear relationship.

[0021] Figure 5 is the response and recovery curve of the sensor made in Example 1 to 100 ppm acetone, Figure 5 It can be seen that the response time of the sensor produced in Example 1 to the acetone test gas at an operating temperature of 310° C. is 7 s and the recovery time is 23 s, which shows that the sensor produced in Example 1 can achieve the purpose of rapid detection of acetone and exhibits good gas-sensitive performance. DETAILED DESCRIPTION

[0022] The above contents of the present invention are further described in detail below through examples, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples, and all technologies implemented based on the above contents of the present invention belong to the scope of the present invention.

[0023] Example 1

[0024] The CDs / Au / ZnO gas sensitive sensing material was prepared and the acetone gas sensor was made. The specific process is as follows:

[0025] Take 0.5g of citric acid and dissolve it in 10mL of deionized water, slowly add 320μL of ethylenediamine, transfer the mixed solution to a high-pressure reactor and keep it at 180℃ for 8h, wait for the high-pressure reactor to cool naturally to room temperature, dialyze the resulting solution with a dialysis bag for 3d, and then filter it with a 0.22μm filter membrane, and then place the filtrate in an oven at 100℃ to dry for 10h, and finally obtain solid CDs with reducing properties.

[0026] Solid CDs were dispersed in deionized water to obtain a CDs solution with a concentration of 0.5 mg / mL. 7 mL of the CDs solution with a concentration of 0.5 mg / mL was taken, 1 mL of a 0.02 M sodium hydroxide solution was added and mixed evenly, and 0.005 mmol of HAuCl4 solution was added dropwise to make the total volume of the solution reach 10 mL. The solution was allowed to stand at room temperature. After several hours of reaction, the color of the solution gradually turned purple-red, thereby obtaining a CDs / Au precursor solution.

[0027] Take 1 mmol of zinc acetate and dissolve it in 20 mL of deionized water, then take 10 mL of the prepared CDs / Au precursor solution and add it to the zinc acetate solution; continue to add 20 mL of an aqueous solution composed of 1.4 mmol of anhydrous sodium sulfate and 2 mmol of anhydrous sodium carbonate dropwise, and stir for 20 minutes; transfer the above mixed solution to a high-pressure reactor, place it in an oven at 180°C for 2 hours, wait for the high-pressure reactor to naturally cool to room temperature, collect the bottom precipitate by centrifugation, and wash it twice with deionized water and ethanol respectively; place it in a vacuum drying oven at 60°C and dry it for 5 hours, and then calcine it at 500°C for 2 hours under N2 atmosphere to finally obtain CDs / Au / ZnO gas sensitive sensing material.

[0028] A small amount of the prepared CDs / Au / ZnO gas-sensitive sensing material is placed in a mortar, and an appropriate amount of ethanol solution is added, followed by continuous grinding with a pestle to obtain a paste; a certain amount of the paste is dipped with a brush and evenly applied to an alumina ceramic tube containing gold electrodes at both ends, and then placed in a 60°C oven to dry for 10 minutes; a nickel-chromium heating wire is used as a heater, and the working temperature is controlled by adjusting the heating voltage; the ceramic tube containing the nickel-chromium heating wire is then welded to a high-temperature resistant base; finally, the prepared gas sensor is aged at 350°C for 72 hours, and finally a gas sensor with a CDs / Au / ZnO gas-sensitive sensing material as a sensing layer is prepared, which can realize the detection of acetone gas.

[0029] Comparative Example 1

[0030] The ZnO gas-sensitive sensing material is prepared and the acetone gas sensor is made. The specific process is as follows:

[0031] Take 1mmol of zinc acetate and dissolve it in 30mL of deionized water, add 20mL of an aqueous solution composed of 1.4mmol of anhydrous sodium sulfate and 2mmol of anhydrous sodium carbonate dropwise, and stir for 20min; transfer the mixed solution to a high-pressure reactor, place it in an oven at 180℃ for 2h, wait for the high-pressure reactor to cool naturally to room temperature, collect the bottom precipitate by centrifugation, and wash it twice with deionized water and ethanol respectively; place it in a vacuum drying oven at 60℃ and dry it for 5h, and then calcine it at 500℃ for 2h under N2 atmosphere to finally obtain ZnO gas sensitive sensing material.

[0032] A small amount of the prepared ZnO gas sensitive sensor material is placed in a mortar, and an appropriate amount of ethanol solution is added, followed by continuous grinding to obtain a paste; a certain amount of the paste is dipped with a brush and evenly applied to an alumina ceramic tube with gold electrodes at both ends, and the tube is placed in a 60°C oven and dried for 10 minutes; a nickel-chromium heating wire is used as a heater, and the working temperature is controlled by adjusting the heating voltage; the ceramic tube containing the nickel-chromium heating wire is then welded to a high-temperature resistant base; finally, the prepared gas sensor is aged at 350°C for 72 hours, and finally a gas sensor with a ZnO gas sensitive sensor material as a sensing layer is prepared for the detection of acetone gas.

[0033] Comparative Example 2

[0034] The CDs / ZnO gas sensitive sensing material was prepared and the acetone gas sensor was made. The specific process is as follows:

[0035] Take 0.5g of citric acid and dissolve it in 10mL of deionized water, slowly add 320μL of ethylenediamine, transfer the mixed solution to an autoclave, keep it at 180℃ for 8h, wait for the autoclave to cool naturally to room temperature, dialyze the obtained solution with a dialysis bag for 3d, filter it with a 0.22μm filter membrane, and then place the filtrate in an oven at 100℃ to dry for 10h, and finally obtain solid CDs with reducing properties.

[0036] Take 1mmol of zinc acetate and dissolve it in 30mL of deionized water, add 3.5mg of CDs, mix well and then add 20mL of an aqueous solution composed of 1.4mmol of anhydrous sodium sulfate and 2mol of anhydrous sodium carbonate dropwise, and stir for 20min; transfer the mixed solution to a high-pressure reactor, place it in an oven at 180℃ for 2h, wait for the high-pressure reactor to cool naturally to room temperature, collect the bottom precipitate by centrifugation, wash it twice with deionized water and ethanol respectively; place it in a vacuum drying oven at 60℃ and dry it for 5h, and then calcine it at 500℃ for 2h in a N2 atmosphere to finally obtain CDs / ZnO gas sensitive sensing material.

[0037] A small amount of the prepared CDs / ZnO gas-sensitive sensing material is placed in a mortar, and an appropriate amount of ethanol solution is added, followed by continuous grinding to obtain a paste; a certain amount of the paste is dipped with a brush and evenly applied to an alumina ceramic tube with gold electrodes at both ends, and the tube is placed in a 60°C oven and dried for 10 minutes; a nickel-chromium heating wire is used as a heater, and the working temperature is controlled by adjusting the heating voltage; the ceramic tube containing the nickel-chromium heating wire is then welded to a high-temperature resistant base; finally, the prepared gas sensor is aged at 350°C for 72 hours, and finally a gas sensor with CDs / ZnO gas-sensitive sensing material as the sensing layer is prepared for the detection of acetone gas.

[0038] Comparative Example 3

[0039] The Au / ZnO gas sensitive sensing material was prepared and the acetone gas sensor was made. The specific process is as follows:

[0040] Take 1mmol of zinc acetate and dissolve it in 30mL of deionized water, then add polyvinyl pyrrolidone (PVP, 0.5g) and glycine (2.7mmol), and stir vigorously to form a uniform solution; then add 20mL of an aqueous solution composed of 1.4mmol of anhydrous sodium sulfate and 2mmol of anhydrous sodium carbonate dropwise, and stir for 20min; transfer the above mixed solution to a high-pressure reactor, place it in an oven at 180℃ for 2h, wait for the high-pressure reactor to cool naturally to room temperature, collect the bottom precipitate by centrifugation, and wash it twice with deionized water and ethanol respectively; place it in a vacuum drying oven at 60℃ and dry it for 5h, and then calcine it at 500℃ for 2h in a N2 atmosphere to finally obtain Au / ZnO gas sensitive sensing material.

[0041] A small amount of the prepared Au / ZnO gas sensitive sensor material is placed in a mortar, and an appropriate amount of ethanol solution is added, followed by continuous grinding to obtain a paste; a certain amount of the paste is dipped with a brush and evenly applied to an alumina ceramic tube with gold electrodes at both ends, and the tube is placed in a 60°C oven for drying for 10 minutes; a nickel-chromium heating wire is used as a heater, and the working temperature is controlled by adjusting the heating voltage; the ceramic tube containing the nickel-chromium heating wire is then welded to a high-temperature resistant base; finally, the prepared gas sensor is aged at 350°C for 72 hours, and finally a gas sensor with Au / ZnO gas sensitive sensor material as the sensing layer is prepared for the detection of acetone gas.

[0042] The above embodiments describe the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for illustrating the principles of the present invention. Without departing from the scope of the principles of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for preparing CDs / Au / ZnO gas sensitive sensing material, characterized in that The specific process is: Step S1: solid CDs are dispersed in deionized water to obtain a CDs solution with a concentration of 0.5 mg / mL, 7-10 mL of the CDs solution with a concentration of 0.5 mg / mL is taken, 1-2 mL of a 0.02 M sodium hydroxide solution is added and mixed evenly, and then 0.005 mmol of HAuCl4 solution is added dropwise, and the mixed solution is reacted at room temperature for 4-10 hours, and the color of the solution turns purple-red, thereby obtaining a CDs / Au precursor solution reduced by CDs; Step S2: Take 1 mmol of zinc acetate and dissolve it in 20-30 mL of deionized water, then add the CDs / Au precursor solution prepared in step S1 to the zinc acetate solution, continue to dropwise add 20-30 mL of an aqueous solution composed of 1.4 mmol of anhydrous sodium sulfate and 2 mmol of anhydrous sodium carbonate, stir for 20-30 min, transfer the mixed solution to a high-pressure reactor, and then place it in an oven at 180° C. for 2-3 h, wait for the high-pressure reactor to cool naturally to room temperature, collect the bottom precipitate by centrifugation, wash it with deionized water and anhydrous ethanol several times, and then place it in a vacuum drying oven at 60° C. for 5-6 h, and finally calcine it at 500° C. for 2-5 h in a N2 atmosphere to obtain a CDs / Au / ZnO gas sensitive sensing material; In the CDs / Au / ZnO gas-sensitive sensing material, CDs / Au nanoparticles are uniformly distributed on the nanorod ZnO, wherein the length of the ZnO nanorod is 35-70 nm, the particle size of the CDs / Au nanoparticles is 18-20 nm, and the CDs / Au nanoparticles are in a monodisperse state. The CDs / Au / ZnO gas-sensitive sensing material is applied to an alumina ceramic tube containing a gold electrode to prepare a gas sensor for selectively detecting acetone gas, thereby achieving high response, high selectivity, and rapid response and recovery to acetone gas, and can detect low-concentration acetone gas.

2. The method for preparing the CDs / Au / ZnO gas sensitive sensor material according to claim 1, characterized in that The specific preparation process of the solid CDs in step S1 is as follows: 0.5-1 g of citric acid is dissolved in 5-10 mL of deionized water, and then 300-350 μL of ethylenediamine is added, and the mixed solution is transferred to a high-pressure reactor and maintained at 180° C. for 8-10 hours. After the high-pressure reactor is naturally cooled to room temperature, the obtained solution is dialyzed with a dialysis bag for 3-5 days, and then filtered with a 0.22 μm filter membrane, and then the filtrate is dried in an oven at 100° C. for 10-12 hours to finally obtain solid CDs with reducing properties.

3. Application of the CDs / Au / ZnO gas sensitive sensing material prepared according to the method of claim 1 or 2 in an acetone gas sensor, characterized in that: The CDs / Au / ZnO gas sensitive sensing material is applied to an alumina ceramic tube containing a gold electrode, and the manufactured gas sensor is used for selectively detecting acetone gas.

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