Method for preparing gas sensor based on SnO2 doped CeO2 nano material

Abstract

The invention discloses a method for preparing a gas sensor based on a SnO2-doped CeO2 nano material, which comprises the following steps: setting different molar ratios of tin salt and cerium salt, respectively dissolving the tin salt and the cerium salt in deionized water, and continuously stirring until the tin salt and the cerium salt are completely dissolved to form different homogeneous precursor solutions; the preparation method comprises the following steps: firstly atomizing different homogeneous precursor solutions, combusting by using layered plane flame at 700-800 DEG C, then cooling, realizing rapid nucleation and deposition of particles by using a large temperature gradient, collecting to obtain SnO2-doped CeO2 nano-powder, and calcining the SnO2-doped CeO2 nano-powder; the calcined powder and ethyl alcohol are mixed into slurry, and the indirectly-heated gas sensing element is prepared; testing response conditions, response / recovery time and long-term stability of each indirectly-heated gas sensing element to hydrogen at different temperatures, and screening out a tin salt and cerium salt molar ratio with optimal performance in a required test environment; the required gas sensor is prepared after the slurry with the optimal molar ratio is used for coating. The gas sensor has relatively good selectivity, relatively high sensitivity and relatively high response speed on hydrogen.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor metal oxide gas sensor technology, specifically a method for preparing a gas sensor based on SnO2-doped CeO2 nanomaterials. Background Technology

[0002] Hydrogen, as a new energy source, boasts a high calorific value, rapid combustion, and pollution-free combustion products. Currently, it is primarily used as an industrial raw material in petroleum, chemical, fertilizer, and metallurgical industries. As a clean and efficient secondary energy source, hydrogen plays a crucial role in building a multi-energy complementary system based primarily on renewable energy. While hydrogen energy offers advantages such as high efficiency and cleanliness, and is poised to replace traditional energy sources in the future, its low density makes it prone to leakage from orifices and it exhibits strong diffusivity. In the event of a leak, hydrogen will rapidly disperse into the surrounding environment. Furthermore, hydrogen's explosive limits range from 4% to 75%, a wide range with a very low lower explosive limit, meaning that a leak will quickly reach this limit. Additionally, hydrogen has a very low minimum ignition energy, approximately 0.02 mJ, the lowest among combustible gases. Therefore, hydrogen leaks have a significant potential for explosions. Hydrogen explosions are extremely destructive, causing severe damage to surrounding facilities, buildings, structures, and people, potentially leading to even more serious disasters. The current consumption of hydrogen is very large and is increasing year by year. At the same time, the requirements for its preparation, storage, transportation and use are extremely strict. The urgent problem to be solved is the safety of hydrogen production, storage and transportation. It is of great significance to develop a gas sensor that can accurately detect hydrogen and avoid its explosion that could cause serious casualties and property damage.

[0003] Currently, the materials used in gas sensors that are crucial to their performance are mainly synthetic metal semiconductor oxide nanomaterials, which are commonly prepared using methods such as hydrothermal deposition, sol-gel deposition, vapor deposition, and magnetron sputtering. However, these existing methods are complex, costly, and produce large-sized products, ultimately resulting in sensors with low sensitivity to hydrogen and slow response times.

[0004] Therefore, the research direction of this invention is to provide a new preparation method that enables the gas sensor to have better selectivity, higher sensitivity, and faster response speed to hydrogen. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method for preparing a gas sensor based on SnO2-doped CeO2 nanomaterials. By controlling the morphology and size appropriately, the specific surface area of ​​the nanomaterials is increased, and the reactive sites are increased, so that the gas sensor prepared by it has good selectivity for hydrogen, high sensitivity, and fast response speed.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a method for preparing a gas sensor based on SnO2-doped CeO2 nanomaterials, comprising the following steps: Step 1: Dissolve the tin salt and cerium salt in deionized water according to the set molar ratio of tin salt and cerium salt, and continue stirring until completely dissolved to form a homogeneous precursor solution; Step 2: The homogeneous precursor liquid from Step 1 is first atomized and then cooled after combustion in a layered planar flame at 700~800℃. The large temperature gradient is used to achieve rapid nucleation and deposition of particles. SnO2-doped CeO2 nanopowder is collected and calcined. Step 3: Mix the calcined powder with ethanol to form a slurry, grind it, coat it evenly on an Al2O3 ceramic tube with a platinum electrode, and dry it. After drying at 400℃ for 2 hours, weld on a nickel-chromium heating wire to make a side-heated gas sensing element, and then perform an aging treatment. Step 4: Set different molar ratios of tin salt and cerium salt, and repeat steps 1 to 3 respectively to obtain side-heated gas sensing elements prepared with different doping ratios. Step 5: Test the response of each side-heated gas sensing element obtained in Step 4 to hydrogen at different temperatures, the response / recovery time and long-term stability, and screen out the optimal molar ratio of tin salt to cerium salt under the required test environment. Step 6: The slurry corresponding to the molar ratio selected in Step 5 is coated onto the portable semiconductor gas sensor to produce the required gas sensor.

[0007] Furthermore, in step one, the tin salt is SnCl2·2H2O or SnCl4·5H2O, and the cerium salt is one of Ce(NO3)4Ⅳ, Ce(NO3)3·6H2O, CeCl3·7H2O, or (NH4)2Ce(NO3)6.

[0008] Furthermore, the concentration of tin salt in the homogeneous precursor solution of step one is not less than 0.2 mol.

[0009] Furthermore, the preparation of nanoparticles in step two is achieved using a synthesis generating device, which includes a jet atomizing device, a conveying pipe, a conical burner, a solid-phase water-cooled substrate, and a gas flow control system. The jet atomizing device is connected to the conical burner through the conveying pipe. The slurry is injected into the jet atomizing device and atomized by the input gas, and then transported to the conical burner through the conveying pipe. The conical burner is positioned above the solid-phase water-cooled substrate, and the flame generated by the combustion of combustible gas in the conical burner is directed towards the solid-phase water-cooled substrate, forming a layered planar flame of 700~800℃ above the solid-phase water-cooled substrate to burn the atomized slurry. The synthesis product after combustion falls onto the solid-phase water-cooled substrate and is rapidly cooled to obtain SnO2-doped CeO2 nanoparticles. The gas flow control system is used to control the gas flow rate entering the jet atomizing device and the conical burner.

[0010] Furthermore, the preheating temperature of the conveying pipeline is 60~70℃; the burner is filled with ethylene, oxygen and nitrogen loaded with homogeneous precursor liquid, and an inert protective gas (nitrogen) is introduced into the outer layer; the solid phase water-cooled substrate is a stainless steel disc with a diameter of 15cm and a thickness of 2.5cm, and its interior is equipped with a serpentine channel filled with cooling water to keep its temperature at 10~15℃.

[0011] Furthermore, in step two, a temperature measuring device is used to test the center temperature of the layered planar flame. This device includes a fixed platform, a moving platform, a thermocouple, and two ceramic jackets. The fixed platform has a track on its upper part, and the moving platform has a guide rail on its lower part. The moving platform is mounted on the track of the fixed platform via the guide rail, allowing it to move relative to the fixed platform along the track. The two ceramic jackets are arranged parallel to each other on the moving platform. The thermocouple is located between one end of the two ceramic jackets, and both ends of the thermocouple are connected to a temperature measuring instrument via the ceramic jackets. A spring is located between the two ceramic jackets near their other ends, and the spring applies a pre-tension force to keep the thermocouple taut. When the moving platform moves the thermocouple to the center of the layered planar flame, the thermocouple measures the temperature at the center of the flame and obtains the temperature data through the temperature measuring instrument. After completion, the moving platform moves the thermocouple away from the flame.

[0012] Furthermore, in step two, the collected nanoparticles are calcined at 600°C for 2 hours.

[0013] Furthermore, the aging process in step three specifically involves aging the side-heated gas sensing element at 180°C under a heating voltage on an aging table for 72 hours.

[0014] Furthermore, in step five, the optimal molar ratio of tin salt to cerium salt was selected as 20:1.

[0015] Compared with the prior art, the present invention has the following significant advantages: (1) The present invention synthesizes SnO2-doped CeO2 nanomaterials and uses a large temperature gradient to achieve rapid nucleation and deposition of particles. The obtained nanomaterials have the characteristics of small particle size (minimum average particle size of 17.72 nm), uniform distribution and high specific surface area.

[0016] (2) The present invention controls the flame temperature at 700~800℃ by adjusting the ratio of oxygen to ethylene, forming a stable layered planar flame, and precisely controls the molar ratio of tin source to cerium source, thereby accurately obtaining nanomaterials with different doping ratios, realizing the precise preparation of nanomaterials with the required ratio, which is convenient for subsequent fabrication of gas sensors.

[0017] (3) In this invention, SnO2-doped CeO2 nanomaterials of different proportions are used to make side-heated sensors, and the performance of gas sensors of different proportions is tested. The optimal molar ratio of tin salt to cerium salt is selected, and the slurry corresponding to the molar ratio is coated on the portable semiconductor gas sensor to make a portable gas sensor with good selectivity, high sensitivity and fast response speed for hydrogen. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the synthesis generating apparatus in this invention.

[0019] Figure 2 This is a schematic diagram of the temperature measuring device in this invention.

[0020] Figure 3 for Figure 2 Top view.

[0021] Figure 4 The image shows the XRD pattern of the product.

[0022] The SnO2-doped CeO2 nanomaterials prepared in Examples 3 and 4 correspond to standard cards PDF#71-0652 and PDF#81-0792, respectively.

[0023] Figure 5 This is the EDS diagram of the product from Example 6.

[0024] Figure 6 SEM images of the products from Examples 1 to 6.

[0025] Figure 7 This is a mapping diagram of the product elements in Example 4.

[0026] Among them, (a) HAADF diagram, (b) Sn element diagram, (c) O element diagram and (d) Ce element spectrum.

[0027] Figure 8 This is a particle size distribution diagram of the product from Example 4.

[0028] Figure 9 The graph shows a comparison of the response values ​​of the gas sensors prepared in Examples 1 to 6 and the gas sensors in Comparative Examples 1 and 2 to 300 ppm hydrogen at 240~400°C.

[0029] In the diagram: 1-jet atomizing device, 2-conveying pipe, 3-conical burner, 4-solid phase water-cooled substrate, 5-gas flow control system, 2-1-fixed platform, 2-2-track, 2-3-moving platform, 2-4-spring, 2-5-ceramic jacket, 2-6-thermocouple. Detailed Implementation

[0030] The present invention will be further described below with reference to embodiments.

[0031] Example 1: Weigh 0.7012 g of SnCl4·5H2O and 0.7763 g of Ce(NO3)4•Ⅳ using an analytical balance, add them to 10 mL of deionized water, and stir until homogeneous to obtain a homogeneous mixed solution with a Sn:Ce molar ratio of 1:1, which serves as the homogeneous precursor solution. Nanomaterials are prepared using a synthesis generator. Specifically, the inlet rates of ethylene, oxygen, carrier gas (nitrogen), atomizing and breaking gas, and inert protective gas (nitrogen) are adjusted using a gas flow control system 5. The temperature of the flame plane center is measured using a temperature measuring device. Thermocouples 2-6 in the temperature measuring device are OMEGAP13R-010 thermocouples, and the temperature of the layered planar flame is controlled at 1046 K. The temperature of the preheating device in the delivery pipeline 2 is preheated to 70 °C, and the circulating water cooling system is turned on to control the temperature of the solid water-cooled substrate 4 at approximately 10 °C. The distance between the solid water-cooled substrate 4 and the nozzle of the conical burner 3 is 30 mm, and the deposition time of the synthesis product on the solid water-cooled substrate 4 is 20 min. The product was then annealed at 600°C for 3 hours in a tubular furnace. The calcined powder was mixed with ethanol to form a slurry, ground, and then uniformly coated onto an Al2O3 ceramic tube with a platinum electrode. After drying at 400°C for 2 hours, a nickel-chromium heating wire was welded on to fabricate a side-heated gas sensing element, which was then aged at 180°C for 72 hours on an aging table. The product and corresponding sensor of Example 1 are denoted as 1SnO2:CeO2.

[0032] The above-mentioned synthesis generating apparatus, such as Figure 1As shown, it includes a jet atomizing device 1, a conveying pipe 2, a conical burner 3, a solid-phase water-cooled substrate 4, and a gas flow control system 5. The jet atomizing device 1 is connected to the conical burner 3 through the conveying pipe 2. The slurry is injected into the jet atomizing device 1 and atomized by the input gas. After being broken, mixed, and atomized, it is transported to the conical burner 3 through the conveying pipe 2. The conical burner 3 is located above the solid-phase water-cooled substrate 4, and the flame generated by the combustion of combustible gas in the conical burner 3 is directed towards the solid-phase water-cooled substrate 4, so that a layered planar flame of 700~800℃ is formed above the solid-phase water-cooled substrate 4 to burn the atomized slurry. The synthesized product after combustion falls onto the solid-phase water-cooled substrate 4 and is rapidly cooled to obtain SnO2-doped CeO2 nanopowder. The gas flow control system 5 is used to control the gas flow rate entering the jet atomizing device 1 and the conical burner 3.

[0033] The center temperature of a layered planar flame is measured using a temperature measuring device, such as... Figure 2 and 3 As shown, it includes a fixed platform 2-1, a movable platform 2-3, a thermocouple 2-6, and two ceramic jackets 2-5. The fixed platform 2-1 has a track 2-2 on its upper part, and the movable platform 2-3 has a guide rail on its lower part. The movable platform 2-3 is mounted on the track 2-2 of the fixed platform 2-1 via the guide rail, allowing it to move relative to the fixed platform 2-1 along the track 2-2. The two ceramic jackets 2-5 are arranged parallel to each other on the movable platform 2-3, and the thermocouple 2-6 is located within the two ceramic jackets. Between one end of 2-5, and both ends of thermocouple 2-6 are connected to the thermometer via ceramic jackets 2-5. A spring 2-4 is provided between the two ceramic jackets 2-5 near the other end. The spring 2-4 applies a pre-stressed tension to keep thermocouple 2-6 in a taut state. When the moving platform 2-3 moves thermocouple 2-6 to the center of the layered planar flame, thermocouple 2-6 measures the temperature of the flame center and obtains the temperature data through the thermometer. After completion, the moving platform 2-3 moves thermocouple 2-6 away from the flame.

[0034] Example 2: The entire preparation process was basically the same as in Example 1, except that: 0.7012 g of SnCl4·5H2O and 0.1526 g of Ce(NO3)4•Ⅳ were weighed using an analytical balance, added to 10 mL of deionized water, and stirred until homogeneous to obtain a homogeneous mixed solution with a Sn:Ce molar ratio of 5:1, which served as the homogeneous precursor solution. The product and corresponding sensor of Example 2 are denoted as 5SnO2:CeO2.

[0035] Example 3: The entire preparation process was basically the same as in Example 1, except that: 0.7012 g of SnCl4·5H2O and 0.0776 g of Ce(NO3)4•Ⅳ were weighed using an analytical balance, added to 10 mL of deionized water, and stirred until homogeneous to obtain a homogeneous mixed solution with a Sn:Ce molar ratio of 10:1, which served as the homogeneous precursor solution. The product and corresponding sensor of Example 3 are denoted as 10SnO2:CeO2.

[0036] Example 4: The entire preparation process was basically the same as in Example 1, except that: 0.7012 g of SnCl4·5H2O and 0.0388 g of Ce(NO3)4•Ⅳ were weighed using an analytical balance, added to 10 mL of deionized water, and stirred until homogeneous to obtain a homogeneous mixed solution with a Sn:Ce molar ratio of 20:1, which served as the homogeneous precursor solution. The product and corresponding sensor of Example 4 are denoted as 20SnO2:CeO2.

[0037] Example 5: The entire preparation process was basically the same as in Example 1, except that: 0.7012 g of SnCl4·5H2O and 0.01526 g of Ce(NO3)4•Ⅳ were weighed using an analytical balance, added to 10 mL of deionized water, and stirred until homogeneous to obtain a homogeneous mixed solution with a Sn:Ce molar ratio of 50:1, which served as the homogeneous precursor solution. The product and corresponding sensor of Example 5 are denoted as 50SnO2:CeO2.

[0038] Example 6: The entire preparation process was basically the same as in Example 1, except that: 0.7012 g of SnCl4·5H2O and 0.00776 g of Ce(NO3)4•Ⅳ were weighed using an analytical balance, added to 10 mL of deionized water, and stirred until homogeneous to obtain a homogeneous mixed solution with a Sn:Ce molar ratio of 100:1 as the homogeneous precursor solution. The product and corresponding sensor of Example 6 are denoted as 100SnO2:CeO2.

[0039] Comparative Example 1: Weigh 0.7012 g of SnCl4·5H2O using an analytical balance and add it to 10 mL of deionized water. Stir until homogeneous to obtain a homogeneous mixed solution of tin source as the precursor. The other preparation procedures are the same as in Example 1. The product and corresponding sensor of Comparative Example 1 are denoted as SnO2.

[0040] Comparative Example 2: Weigh 0.7763 g of Ce(NO3)4•Ⅳ using an analytical balance, add it to 10 mL of deionized water, and stir until homogeneous to obtain a homogeneous mixed solution of cerium source as a precursor. The other preparation process is the same as in Example 1. The product and corresponding sensor of Comparative Example 2 are denoted as CeO2.

[0041] Testing and Screening: The products and gas sensors prepared in Examples 1 to 6, Comparative Examples 1 and 2 were tested and analyzed. Figure 4 The figures show the XRD patterns of the SnO2-doped CeO2 nanomaterials prepared in Examples 3 and 4. As can be seen from the figures, both SnO2 and CeO2 were synthesized by flame. All diffraction peaks in the figures correspond to the SnO2 standard card (PDF#71-0652) and the CeO2 standard card (PDF#81-0792). The two products mainly correspond to the three main diffraction peaks of SnO2 in the 2θ range of 20° to 80°, namely the (110), (101), and (211) crystal planes; and also correspond to the three main diffraction peaks of CeO2, namely the (111), (220), and (311) crystal planes. Furthermore, the absence of impurity peaks in the figures indicates that both Examples 3 and 4 formed uniform single-phase materials.

[0042] Figure 5 The image shows the EDS spectrum of the product from Example 6. The approximate distribution of O, Sn, and Ce elements can be seen in the figure, indicating the phase purity of the synthesized product. The atomic ratio of Sn to Ce is approximately 100:1, indicating that the atomic ratio of the synthesized product is consistent with the ion molar ratio of the precursor solution.

[0043] Figure 6 The images show SEM images of the products from Examples 1 to 6. The images show that the synthesized products have good dispersion and small particles, exhibiting a stacked, fine sand-like structure at a 500nm scale. The particle surfaces are relatively smooth with clear boundaries, indicating that this invention utilizes a large temperature gradient to achieve rapid nucleation and deposition of particles, resulting in small nanomaterial particles. Furthermore, a comparison of Examples 1 to 6 reveals that Example 4, with a SnO2 to CeO2 doping ratio of 20:1, exhibits the most uniform product morphology; other doping ratios result in larger CeO2 particles.

[0044] Figure 7 This is a mapping image of a partial region of the product 4 in SnO2-doped CeO2. O, Sn, and Ce are uniformly distributed in the particles, and a small amount of CeO2 nanoparticles are uniformly dispersed on the SnO2 surface. However, the Ce content is low, so the Ce distribution map is lighter in color.

[0045] Figure 8 The figure shows the particle size distribution of the product in Example 4. As can be seen from the figure, the particle size distribution is reasonable, with an average particle size of 17.72 ± 3.86 nm.

[0046] Figure 9The graph shows a comparison of the response values ​​of the sensors in Examples 1 to 6 and Comparative Examples 1 and 2 to 300 ppm hydrogen at 240–400 °C. The performance indicators show a clear trend with changes in the SnO2 to CeO2 ratio. In Example 4, when the SnO2 to CeO2 doping ratio is 20:1, the maximum response value to 300 ppm hydrogen is 9.25, and the optimal operating temperature is 280 °C. Comparative Example 1 has a lower response value than Example 4, and Comparative Example 2 shows almost no response to 300 ppm hydrogen. This indicates that the SnO2 to CeO2 ratio has a significant impact on material performance, and the performance of each example is significantly better than that of Comparative Example 2. Furthermore, two examples (Examples 4 and 5) show better performance than Comparative Example 1 in the 260–280 °C range, further illustrating the technical effectiveness of the preparation method of this invention. From a comprehensive perspective, Example 4 is the optimal example, maximizing performance indicators and providing better stability.

[0047] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for fabricating a gas sensor based on SnO2-doped CeO2 nanomaterials, characterized in that, Includes the following steps: Step 1: Dissolve the tin salt and cerium salt in deionized water according to the set molar ratio of tin salt and cerium salt, and continue stirring until completely dissolved to form a homogeneous precursor solution; Step 2: The homogeneous precursor liquid from Step 1 is first atomized and then deposited and cooled by combustion in a layered planar flame at 700~800℃. The large temperature gradient is used to achieve rapid nucleation and deposition of particles. SnO2-doped CeO2 nanopowder is collected and calcined. Step 3: Mix the calcined powder with ethanol to form a slurry, grind it, coat it evenly on an Al2O3 ceramic tube with a platinum electrode, and dry it. Then, weld a nickel-chromium heating wire to make a side-heated gas sensing element and perform an aging treatment. Step 4: Set different molar ratios of tin salt and cerium salt, and repeat steps 1 to 3 respectively to obtain side-heated gas sensing elements prepared with different doping ratios. Step 5: Test the response of each side-heated gas sensing element obtained in Step 4 to hydrogen at different temperatures, the response / recovery time and long-term stability, and screen out the optimal molar ratio of tin salt to cerium salt under the required test environment. Step 6: Coat the gas sensor with the slurry corresponding to the molar ratio selected in Step 5 to produce the required gas sensor.

2. The method for preparing a gas sensor based on SnO2-doped CeO2 nanomaterials according to claim 1, characterized in that, In step one, the tin salt is SnCl2·2H2O or SnCl4·5H2O, and the cerium salt is one of Ce(NO3)4Ⅳ, Ce(NO3)3·6H2O, CeCl3·7H2O, or (NH4)2Ce(NO3)6.

3. The method for preparing a gas sensor based on SnO2-doped CeO2 nanomaterials according to claim 1, characterized in that, The concentration of tin salt in the homogeneous precursor solution of step one is not less than 0.2 mol.

4. The method for preparing a gas sensor based on SnO2-doped CeO2 nanomaterials according to claim 1, characterized in that, Step two involves preparing the nanopowder using a synthesis generating device, which includes a jet atomizing device, a conveying pipe, a conical burner, a solid-phase water-cooled substrate, and a gas flow control system. The jet atomizing device is connected to the conical burner via the conveying pipe. The slurry is injected into the jet atomizing device and atomized by input gas, then transported through the conveying pipe to the conical burner. The conical burner is positioned above the solid-phase water-cooled substrate, and the flame generated by the combustion of combustible gas in the conical burner is directed towards the solid-phase water-cooled substrate, forming a layered planar flame at 700-800°C above the solid-phase water-cooled substrate to burn the atomized slurry. The synthesized product after combustion falls onto the solid-phase water-cooled substrate and is rapidly cooled to obtain SnO2-doped CeO2 nanopowder. The gas flow control system is used to control the gas flow rate entering the jet atomizing device and the conical burner.

5. The method for preparing a gas sensor based on SnO2-doped CeO2 nanomaterials according to claim 4, characterized in that, The preheating temperature of the conveying pipeline is 60~70℃; the burner is filled with ethylene, oxygen and nitrogen loaded with homogeneous precursor liquid, and an inert protective gas is introduced into the outer layer; the solid phase water-cooled substrate is a stainless steel disc with a diameter of 15cm and a thickness of 2.5cm, and its interior is arranged with serpentine channels filled with cooling water to keep its temperature at 10~15℃.

6. The method for preparing a gas sensor based on SnO2-doped CeO2 nanomaterials according to claim 1, characterized in that, In step two, a temperature measuring device is used to test the center temperature of the layered planar flame.

7. The method for preparing a gas sensor based on SnO2-doped CeO2 nanomaterials according to claim 1, characterized in that, In step two, the collected nanoparticles are calcined at 600°C for 2 hours.

8. The method for preparing a gas sensor based on SnO2-doped CeO2 nanomaterials according to claim 1, characterized in that, The aging process in step three specifically involves aging the heated gas sensing element at 180°C under a high voltage on an aging table for 72 hours.

9. The method for preparing a gas sensor based on SnO2-doped CeO2 nanomaterials according to claim 1, characterized in that, In step five, the optimal molar ratio of tin salt to cerium salt was selected as 20:1.

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