SnO2-based gas sensitive material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of preparation of gas sensitive materials. The invention discloses a SnO2-based gas sensitive material as well as a preparation method and application thereof. The preparation method comprises the following steps: S1, preparing a SnO2 precursor solution; s2, the SnO2 precursor solution is subjected to a reaction at the temperature of 130-150 DEG C, washing, drying and calcination are carried out, and SnO2 nanosheets are prepared; s3, preparing a Nb precursor solution and a MoS2 precursor solution; and S4, stirring and mixing the SnO2 nanosheets, the Nb precursor solution and the MoS2 precursor solution, adding the halloysite nanotube dispersion liquid, stirring and mixing, reacting at 180-220 DEG C, washing, drying and calcining to obtain the SnO2-based gas sensitive material. The SnO2-based gas sensitive material prepared by the invention is low in working temperature, high in sensitivity and good in long-term stability.

Description

Technical Field

[0001] This application relates to the field of gas-sensitive material preparation technology, and in particular to a SnO2-based gas-sensitive material, its preparation method, and its application. Background Technology

[0002] With the rapid development of air quality monitoring, industrial safety, environmental monitoring, and smart home technologies, the demand for gas detection is increasing. Metal oxide semiconductors are widely used as gas-sensitive materials due to their advantages such as fast response, high response value, and good stability, enabling the detection of different gases.

[0003] Among many metal oxides, tin dioxide (SnO2) has become one of the preferred materials in the field of gas sensors due to its excellent chemical stability and good conductivity. It is used to detect various gases, such as carbon monoxide, hydrogen, formaldehyde, and sulfur dioxide, meeting diverse needs from indoor air quality monitoring to industrial environmental control.

[0004] However, despite the significant achievements of SnO2-based gas-sensitive materials in the field of gas sensing, several challenges remain for the detection of specific gases such as sulfur dioxide. Current SnO2-based sulfur dioxide sensors on the market exhibit obvious limitations in terms of operating temperature, sensitivity, and long-term stability. Specifically, the operating temperature is too high, typically around 400°C, which means high energy consumption and limited application range; insufficient sensitivity limits the sensor's detection capability in low-concentration sulfur dioxide environments; and poor long-term stability leads to a gradual decline in performance over time, affecting data reliability. Chinese patent CN112408463A discloses a high-response-sensitivity SnO2 gas-sensitive material, which solves the problems of high operating temperature and low response sensitivity, but fails to simultaneously maintain high sensitivity and long-term stability.

[0005] Therefore, there is an urgent need to develop a SnO2-based gas-sensitive material with low operating temperature, high sensitivity, and good long-term stability. Summary of the Invention

[0006] In order to solve at least one of the above-mentioned technical problems and develop a SnO2-based gas-sensitive material with low operating temperature, high sensitivity and good long-term stability, this application provides a SnO2-based gas-sensitive material, its preparation method and application.

[0007] On the one hand, this application provides a method for preparing a SnO2-based gas-sensitive material, comprising the following steps: S1. Dissolve SnCl4·5H2O in deionized water, add surfactant and alkaline solution, stir and mix to prepare SnO2 precursor solution; S2. The SnO2 precursor solution is reacted at 130-150°C for 10-24 hours, washed, dried, and calcined to obtain SnO2 nanosheets. S3. Dissolve NbCl5 and (NH4)2MoS4 in ethanol and deionized water, respectively, to prepare Nb precursor solution and MoS2 precursor solution. S4. The SnO2 nanosheets, Nb precursor solution and MoS2 precursor solution are stirred and mixed, halloysite nanotube dispersion is added, stirred and mixed, and reacted at 180-220℃ for 10-24h. The mixture is then washed, dried and calcined to obtain SnO2-based gas-sensitive material.

[0008] By adopting the above technical solution, the structure of the SnO2 nanosheets in this application helps to improve the response speed and sensitivity of the gas-sensitive material, while the calcination process enhances the stability of the gas-sensitive material. Nb precursor solution, MoS2 precursor solution, and halloysite nanotube dispersion are added to the SnO2 nanosheets, and a composite material is formed through a high-temperature reaction. The SnO2 nanosheets have a large specific surface area, which is beneficial for the adsorption and detection of gas molecules and can also accelerate the electron transport rate, thereby improving the response time and sensitivity of the sensor. Nb doping can provide SnO2 with additional free electrons, increasing the material's conductivity and optimizing electron mobility, thereby reducing the degradation of material performance under long-term use or high-temperature environments and improving long-term stability. Furthermore, Nb doping may also trap harmful holes or electrons by forming energy traps, preventing them from diffusing in the material and causing performance degradation. MoS2 doping can reduce the grain boundary barrier height in the SnO2-based gas-sensitive material, making it easier for charge carriers to transport within the material, reducing the energy required for gas detection, and thus lowering the operating temperature. The addition of halloysite nanotubes not only improves the mechanical strength and stability of the material, but also provides more gas adsorption sites, further enhancing sensitivity and stability.

[0009] Therefore, the SnO2-based gas-sensitive material prepared by the method of this application effectively reduces the operating temperature and improves the sensitivity and long-term stability.

[0010] Optionally, in step S1, the weight ratio of SnCl4·5H2O, deionized water, and alkaline solution is 1:10-20:0.05-0.1; the surfactant accounts for 0.1-1% of the SnO2 precursor solution; and the mass fraction of the alkaline solution is 2-5%.

[0011] By adopting the above technical solution, the amount of surfactant added in this application can reduce the interaction forces between particles in the solution, promote uniform dispersion, avoid agglomeration, and help improve the performance of the final gas-sensitive material. The amount of alkali added ensures a moderately alkaline environment in the solution, while avoiding side reactions or structural damage caused by excessive alkali.

[0012] Optionally, in step S1, the surfactant is selected from one of octadecyl dimethyl benzyl ammonium chloride, hexadecyl pyridine bromide, and dodecyl trimethyl ammonium chloride; The alkaline solution is selected from either urea or ammonia water.

[0013] By adopting the above technical solution, the surfactant in this application can effectively reduce particle aggregation, promote the uniform dispersion of SnO2 precursor, and help form a more uniform nanostructure. The alkaline solution used in this application is either urea or ammonia water, which is milder and avoids excessively vigorous side reactions.

[0014] Optionally, in step S3, the weight ratio of NbCl5 to ethanol is 1:20-30; and the weight ratio of (NH4)2MoS4 to deionized water is 1:30-40.

[0015] Optionally, in step S4, the molar ratio of Sn, Nb, and Mo elements in the SnO2 nanosheets, Nb precursor solution, and MoS2 precursor solution is 1:0.05-0.1:0.05-0.1. The halloysite nanotube dispersion accounts for 5-10% of the total weight.

[0016] By adopting the above technical solution, the molar ratio of Sn, Nb and Mo elements in this application helps to control the uniformity of doping, avoid the formation of large defects or phase separation, and thus optimize the overall performance of the material.

[0017] Optionally, in step S2, the drying temperature is 50–70°C and the drying time is 10–15 h; the calcination temperature is 400–600°C and the calcination time is 2–4 h. In step S4, the drying temperature is 50–70°C and the drying time is 10–15 h; the calcination temperature is 400–600°C and the calcination time is 2–4 h.

[0018] By adopting the above technical solution, the drying temperature and drying time of this application ensure drying and avoid cracking or other adverse reactions caused by moisture during subsequent calcination. The calcination temperature and calcination time of this application ensure the complete progress of the reaction and also avoid grain growth or phase transformation caused by excessively high temperatures.

[0019] Optionally, in steps S2 and S4, washing involves centrifuging three times each with deionized water and alcohol.

[0020] By adopting the above technical solution, deionized water will not introduce additional ionic pollution during washing, which helps to maintain the purity and performance of the material; ethanol can further remove organic pollutants on the surface of the material and is easy to volatilize, which is beneficial to subsequent treatment.

[0021] Optionally, in step S4, the halloysite nanotube dispersion is prepared by adding halloysite nanotubes to deionized water and ultrasonically dispersing them to obtain a halloysite nanotube dispersion with a concentration of 1-5%.

[0022] Secondly, this application provides SnO2-based gas-sensitive materials prepared by the above-mentioned method.

[0023] By adopting the above technical solution, the SnO2-based gas-sensitive material prepared by the preparation method of the SnO2-based gas-sensitive material of this application has a low operating temperature, high sensitivity, and good long-term stability.

[0024] Thirdly, this application provides the application of SnO2-based gas-sensitive materials prepared by the above-mentioned method in the detection of sulfur dioxide.

[0025] By adopting the above technical solution, the SnO2-based gas-sensitive material prepared by the method of this application has a low operating temperature, making it suitable for more application scenarios. It exhibits high sensitivity, enabling rapid detection of low concentrations of sulfur dioxide, which is particularly important for air quality monitoring and preventative maintenance. Furthermore, it demonstrates good long-term stability, extending the sensor's lifespan.

[0026] In summary, the present invention has at least one of the following beneficial technical effects: 1. The SnO2-based gas-sensitive material prepared by the method of this application effectively reduces the operating temperature and improves the sensitivity and long-term stability.

[0027] 2. Nb doping in this application can reduce the degradation of material performance under long-term use and improve long-term stability; MoS2 doping can reduce the energy required by the material when detecting gas and lower the operating temperature.

[0028] 3. The addition of halloysite nanotubes provides more gas adsorption sites, further improving sensitivity and stability. Attached Figure Description

[0029] Figure 1 This is a SEM image of the SnO2 nanosheets obtained in step S2 of Example 2 of this application; Figure 2 The graphs show the 90-day long-term stability test results of the sulfur dioxide gas sensors prepared in Application Example 2, Comparative Example 1, and Comparative Example 3 of this application. Detailed Implementation

[0030] The present application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0031] This application designs a method for preparing SnO2-based gas-sensitive materials, including the following steps: S1. Dissolve SnCl4·5H2O in deionized water, add surfactant and alkaline solution, stir and mix to prepare SnO2 precursor solution; S2. The SnO2 precursor solution is reacted at 130-150°C for 10-24 hours, washed, dried, and calcined to obtain SnO2 nanosheets. S3. Dissolve NbCl5 and (NH4)2MoS4 in ethanol and deionized water, respectively, to prepare Nb precursor solution and MoS2 precursor solution. S4. The SnO2 nanosheets, Nb precursor solution and MoS2 precursor solution are stirred and mixed, halloysite nanotube dispersion is added, stirred and mixed, and reacted at 180-220℃ for 10-24h. The mixture is then washed, dried and calcined to obtain SnO2-based gas-sensitive material.

[0032] The SnO2-based gas-sensitive material of this application is prepared by the above-mentioned method for preparing SnO2-based gas-sensitive materials.

[0033] The SnO2-based gas-sensitive material prepared by the method described in this application can be used in the detection of sulfur dioxide.

[0034] The applicant has designed the technical solution described in this application to address the problems of existing SnO2-based gas-sensitive materials, such as excessively high operating temperature, insufficient sensitivity, and poor long-term stability.

[0035] The SnO2-based gas-sensitive material prepared by the method described in this application has a low operating temperature, high sensitivity, and good long-term stability, making it suitable for a wider range of applications.

[0036] The raw materials used in this application are as follows: Octadecyl dimethyl benzyl ammonium chloride: CAS: 122-19-0. Specific Implementation

[0037] Examples 1-3 Example 1 This embodiment provides a SnO2-based gas-sensitive material and its preparation method. The preparation method includes the following steps: S1. Dissolve SnCl4·5H2O in deionized water, add surfactant and alkali solution, stir and mix to prepare SnO2 precursor solution; wherein, the weight ratio of SnCl4·5H2O, deionized water and alkali solution is 1:10:0.05; the surfactant accounts for 1% of the SnO2 precursor solution; the mass fraction of alkali solution is 2%; the surfactant is octadecyl dimethyl benzyl ammonium chloride; the alkali solution is ammonia water; S2. The SnO2 precursor solution was reacted at 150℃ for 10h, centrifuged 3 times each with deionized water and alcohol, dried at 50℃ for 15h, and calcined at 600℃ for 2h to obtain SnO2 nanosheets. S3. NbCl5 and (NH4)2MoS4 were dissolved in ethanol and deionized water, respectively, to prepare Nb precursor solution and MoS2 precursor solution; wherein the weight ratio of NbCl5 to ethanol was 1:20; the weight ratio of (NH4)2MoS4 to deionized water was 1:30. S4. SnO2 nanosheets, Nb precursor solution and MoS2 precursor solution were stirred and mixed, halloysite nanotube dispersion was added, stirred and mixed, reacted at 180℃ for 24h, centrifuged 3 times each with deionized water and ethanol, dried at 70℃ for 10h, and calcined at 500℃ for 3h to obtain SnO2-based gas-sensitive material; wherein the molar ratio of Sn, Nb and Mo was 1:0.07:0.07; the halloysite nanotube dispersion accounted for 5% of the total weight.

[0038] The method for preparing halloysite nanotube dispersion is as follows: Halloysite nanotubes are added to deionized water and ultrasonically dispersed to obtain halloysite nanotube dispersion with a concentration of 5%.

[0039] Example 2 This embodiment provides a SnO2-based gas-sensitive material and its preparation method. The preparation method includes the following steps: S1. Dissolve SnCl4·5H2O in deionized water, add surfactant and alkali solution, stir and mix to prepare SnO2 precursor solution; wherein, the weight ratio of SnCl4·5H2O, deionized water and alkali solution is 1:15:0.07; the surfactant accounts for 0.5% of the SnO2 precursor solution; the mass fraction of alkali solution is 3.5%; the surfactant is octadecyl dimethyl benzyl ammonium chloride; the alkali solution is ammonia water; S2. The SnO2 precursor solution was reacted at 140℃ for 17h, centrifuged 3 times each with deionized water and alcohol, dried at 60℃ for 12h, and calcined at 500℃ for 3h to obtain SnO2 nanosheets. S3. NbCl5 and (NH4)2MoS4 were dissolved in ethanol and deionized water, respectively, to prepare Nb precursor solution and MoS2 precursor solution; wherein the weight ratio of NbCl5 to ethanol was 1:25; the weight ratio of (NH4)2MoS4 to deionized water was 1:35. S4. SnO2 nanosheets, Nb precursor solution and MoS2 precursor solution were stirred and mixed, halloysite nanotube dispersion was added, stirred and mixed, reacted at 200℃ for 17h, centrifuged 3 times each with deionized water and ethanol, dried at 60℃ for 12h, and calcined at 500℃ for 3h to obtain SnO2-based gas-sensitive material; wherein the molar ratio of Sn, Nb and Mo was 1:0.07:0.07; halloysite nanotube dispersion accounted for 7.5% of the total weight.

[0040] The method for preparing halloysite nanotube dispersion is as follows: Halloysite nanotubes are added to deionized water and ultrasonically dispersed to obtain halloysite nanotube dispersion with a concentration of 3%.

[0041] Example 3 This embodiment provides a SnO2-based gas-sensitive material and its preparation method. The preparation method includes the following steps: S1. Dissolve SnCl4·5H2O in deionized water, add surfactant and alkali solution, stir and mix to prepare SnO2 precursor solution; wherein, the weight ratio of SnCl4·5H2O, deionized water and alkali solution is 1:20:0.1; the surfactant accounts for 0.1% of the SnO2 precursor solution; the mass fraction of alkali solution is 5%; the surfactant is octadecyl dimethyl benzyl ammonium chloride; the alkali solution is ammonia water; S2. The SnO2 precursor solution was reacted at 130℃ for 24h, centrifuged 3 times each with deionized water and alcohol, dried at 70℃ for 10h, and calcined at 400℃ for 4h to obtain SnO2 nanosheets. S3. NbCl5 and (NH4)2MoS4 were dissolved in ethanol and deionized water, respectively, to prepare Nb precursor solution and MoS2 precursor solution; wherein the weight ratio of NbCl5 to ethanol was 1:30; the weight ratio of (NH4)2MoS4 to deionized water was 1:40. S4. SnO2 nanosheets, Nb precursor solution and MoS2 precursor solution were stirred and mixed, halloysite nanotube dispersion was added, stirred and mixed, reacted at 220℃ for 10h, centrifuged 3 times each with deionized water and ethanol, dried at 50℃ for 15h, and calcined at 500℃ for 3h to obtain SnO2-based gas-sensitive material; wherein the molar ratio of Sn, Nb and Mo was 1:0.07:0.07; the halloysite nanotube dispersion accounted for 10% of the total weight.

[0042] The method for preparing halloysite nanotube dispersion is as follows: halloysite nanotubes are added to deionized water and ultrasonically dispersed to obtain halloysite nanotube dispersion with a concentration of 1%.

[0043] Comparative Examples 1-3 Comparative Example 1 The difference between Comparative Example 1 and Example 2 is that Comparative Example 1 is not doped with Nb, that is, steps S3 and S4 are as follows: S3. Dissolve (NH4)2MoS4 in deionized water to prepare a MoS2 precursor solution; wherein the weight ratio of (NH4)2MoS4 to deionized water is 1:35. S4. SnO2 nanosheets and MoS2 precursor solution were stirred and mixed, halloysite nanotube dispersion was added, stirred and mixed, and reacted at 200℃ for 17h. The mixture was centrifuged three times each with deionized water and alcohol, dried at 60℃ for 12h, and calcined at 500℃ for 3h to obtain SnO2-based gas-sensitive material; wherein the molar ratio of Sn to Mo was 1:0.07; and the halloysite nanotube dispersion accounted for 7.5% of the total weight.

[0044] Comparative Example 2 The difference between Comparative Example 2 and Example 2 is that Comparative Example 2 is not doped with MoS2, that is, steps S3 and S4 are as follows: S3. Dissolve NbCl5 in ethanol to prepare an Nb precursor solution; wherein the weight ratio of NbCl5 to ethanol is 1:25. S4. SnO2 nanosheets and Nb precursor solution were stirred and mixed, halloysite nanotube dispersion was added, stirred and mixed, and reacted at 200℃ for 17h. The mixture was centrifuged three times each with deionized water and alcohol, dried at 60℃ for 12h, and calcined at 500℃ for 3h to obtain SnO2-based gas-sensitive material. The molar ratio of Sn to Nb was 1:0.07, and the halloysite nanotube dispersion accounted for 7.5% of the total weight.

[0045] Comparative Example 3 The difference between Comparative Example 3 and Example 2 is that Comparative Example 3 did not include halloysite nanotube dispersion, i.e., step S4 is: S4. SnO2 nanosheets, Nb precursor solution and MoS2 precursor solution were stirred and mixed, reacted at 200℃ for 17h, centrifuged three times each with deionized water and alcohol, dried at 60℃ for 12h, and calcined at 500℃ for 3h to obtain SnO2-based gas-sensitive material; wherein the molar ratio of Sn, Nb and Mo elements was 1:0.07:0.07.

[0046] Experimental testing Testing items and testing methods The SnO2-based gas-sensitive materials prepared in Examples 1-3 and Comparative Examples 1-3 were mixed with deionized water at a weight ratio of 1:1, ground into a slurry, uniformly coated on a ceramic substrate, air-dried, and electrode welded to obtain a sulfur dioxide gas sensor, thus obtaining Application Examples 1-3 and Application Comparative Examples 1-3.

[0047] Optimal operating temperature: The gas response values ​​of sulfur dioxide gas sensors prepared in Application Examples 1-3 and Comparative Examples 1-3 to 5 ppm sulfur dioxide were measured at different operating temperatures, and the optimal operating temperature was recorded.

[0048] Gas-sensitive response value: At the optimal operating temperature, the gas-sensitive response values ​​of the sulfur dioxide gas sensors prepared in Application Examples 1-3 and Comparative Examples 1-3 to 5 ppm sulfur dioxide were detected. The formula for calculating the gas-sensitive response value is: S = R a / R g , where R a R is the resistance value of the sample when it is in the atmosphere. g It is the resistance value of the sample after the gas to be tested is introduced.

[0049] Gas sensitivity response value change trend: At the optimal operating temperature, the sulfur dioxide gas sensors prepared in Application Examples 1-3 and Comparative Examples 1-3 were exposed to 5 ppm of sulfur dioxide every 15 days for 90 days, and the change trend of gas sensitivity response value was detected.

[0050] The sulfur dioxide gas sensors prepared in Application Examples 1-3 and Comparative Examples 1-3 were tested for optimal operating temperature, gas-sensitive response value, and trend of gas-sensitive response value. The test results are shown in Table 1.

[0051] Table 1 As can be seen from the test results in Table 1, the sulfur dioxide gas sensors prepared in Examples 1-3 have low optimal operating temperatures, high gas sensitivity response values, and good long-term stability. Therefore, the SnO2-based gas-sensitive materials prepared in Examples 1-3 of this application have low operating temperatures, high sensitivity, and good long-term stability.

[0052] Compared with the undoped SnO2-based gas-sensitive material in Comparative Example 1, the long-term stability of the material is significantly worse. It is inferred that Nb doping can reduce the degradation of material performance under long-term use and improve long-term stability.

[0053] In Comparative Example 2, the optimal operating temperature of the SnO2-based gas-sensitive material prepared without MoS2 doping increased. This suggests that MoS2 doping can reduce the energy required for the material to detect gases and lower the operating temperature.

[0054] In Comparative Example 3, without the addition of halloysite nanotube dispersion, the sensitivity and long-term stability of the SnO2-based gas-sensitive material decreased.

[0055] Examples 4-7 Example 4 The difference between Example 4 and Example 2 is that in step S4 of Example 4, the calcination temperature is 400°C.

[0056] Example 5 The difference between Example 5 and Example 2 is that in step S4 of Example 5, the calcination temperature is 600°C.

[0057] Example 6 The difference between Example 6 and Example 2 is that in step S4 of Example 6, the molar ratio of Sn, Nb and Mo is 1:0.05:0.05.

[0058] Example 7 The difference between Example 7 and Example 2 is that in step S4 of Example 7, the molar ratio of Sn, Nb and Mo is 1:0.1:0.1.

[0059] The SnO2-based gas-sensitive materials obtained in Examples 4-7 were mixed with deionized water at a weight ratio of 1:1, ground into a slurry, uniformly coated on a ceramic substrate, air-dried, and then electrode-welded to obtain a sulfur dioxide gas sensor, thus obtaining Application Examples 4-7.

[0060] The sulfur dioxide gas sensors prepared in Examples 4 to 7 were used to detect the optimal operating temperature, gas-sensitive response value, and the trend of change of the gas-sensitive response value. The detection results are shown in Table 2.

[0061] Table 2 As can be seen from the test results in Table 2, among Examples 4, 5 and 2, the SnO2-based gas-sensitive material prepared in Example 2 has the lowest optimal operating temperature and the best sensitivity.

[0062] Among Examples 6, 7 and 2, the SnO2-based gas-sensitive material prepared in Example 2 has the lowest optimal operating temperature and the best sensitivity.

[0063] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for preparing a Sn02-based gas sensing material, characterized in that, It comprises the following steps: S1, SnCl4.5H2O is dissolved in deionized water, a surfactant and lye are added, and stirring is mixed to prepare a SnO2 precursor solution; S2, the SnO2 precursor solution is reacted at 130-150 DEG C for 10-24h, washed, dried, calcined to prepare SnO2 nanosheet; S3, NbCl5, (NH4)2MoS4 is dissolved in ethanol and deionized water respectively to prepare Nb precursor solution and MoS2 precursor solution; S4, the SnO2 nanosheet, Nb precursor solution and MoS2 precursor solution are stirred and mixed, halloysite nanotube dispersion liquid is added, stirred and mixed, reacted at 180-220 DEG C for 10-24h, washed, dried, calcined to prepare SnO2-based gas sensitive material.

2. The method of claim 1, wherein the Sn02-based gas sensing material is prepared by mixing Sn02 powder and a binder, and then compressing the mixture into a pellet. In the step S1, the weight ratio of SnCl4.5H2O, deionized water and lye is 1:10-20:0.05-0.1; the surfactant accounts for 0.1-1% of the SnO2 precursor solution; the mass fraction of the lye is 2-5%.

3. The method of claim 1, wherein the Sn02-based gas sensing material is prepared by mixing Sn02 powder, a binder, and a solvent. In the step S1, the surfactant is selected from one of octadecyl dimethyl benzyl ammonium chloride, cetylpyridinium bromide, dodecyl trimethyl ammonium chloride; The lye is selected from one of urea, ammonia.

4. The method of claim 1, wherein the Sn02-based gas sensing material is prepared by mixing Sn02 powder, a binder, and a solvent. In the step S3, the weight ratio of NbCl5 and ethanol is 1:20-30; the weight ratio of (NH4)2MoS4 and deionized water is 1:30-40.

5. The method of claim 1, wherein the Sn02-based gas sensing material is prepared by mixing Sn02 powder, a metal oxide powder, and a binder, and then compressing the mixture. In the step S4, the molar ratio of Sn element, Nb element and Mo element in the SnO2 nanosheet, Nb precursor solution and MoS2 precursor solution is 1:0.05-0.1:0.05-0.1; The halloysite nanotube dispersion liquid accounts for 5-10% of the total weight.

6. The method of claim 1, wherein the Sn02-based gas sensing material is prepared by mixing Sn02 powder, a binder, and a solvent. In the step S2, the drying temperature is 50-70 DEG C, and the drying time is 10-15h; the calcination temperature is 400-600 DEG C, and the calcination time is 2-4h; In the step S4, the drying temperature is 50-70 DEG C, and the drying time is 10-15h; the calcination temperature is 400-600 DEG C, and the calcination time is 2-4h.

7. The method of claim 1, wherein the Sn02-based gas sensing material is prepared by mixing Sn02 powder, a binder, and a solvent. In the step S2, step S4, the washing is centrifuged with deionized water and alcohol respectively for 3 times.

8. The method for preparing SnO2-based gas-sensitive materials according to claim 1, characterized in that, In the step S4, the preparation method of the halloysite nanotube dispersion liquid is that halloysite nanotube is added to deionized water, ultrasonic dispersion to prepare halloysite nanotube dispersion liquid, and the concentration is 1-5%.

9. A Sn02-based gas sensitive material, characterized in that, The SnO2-based gas sensitive material is prepared by the preparation method of the SnO2-based gas sensitive material in any one of claims 1-8.

10. The application of the SnO2-based gas sensitive material prepared by the preparation method of the SnO2-based gas sensitive material in any one of claims 1-8 in detecting sulfur dioxide.

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