Preparation method and application of mesoporous silver oxide-tin dioxide nanosphere gas sensitive material
By preparing mesoporous silver oxide-tin dioxide nanosphere gas-sensitive materials, the problem that semiconductor metal oxide gas sensors cannot distinguish between ethanol and formaldehyde at high temperatures has been solved, and efficient and selective detection of formaldehyde at low temperatures has been achieved, with good anti-interference and long lifespan.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XI AN JIAOTONG UNIV
- Filing Date
- 2022-10-21
- Publication Date
- 2026-07-21
Smart Images
Figure CN116106366B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of gas-sensitive materials technology, and relates to a method for preparing mesoporous silver oxide-tin dioxide nanosphere gas-sensitive materials and their application. Background Technology
[0002] Formaldehyde is a ubiquitous indoor pollutant that poses serious health risks. High concentrations of formaldehyde gas can cause eye irritation, respiratory illnesses, impaired immune function, and even cancer. Therefore, there is a need to develop a formaldehyde sensor to monitor and detect indoor pollutants. Semiconductor metal oxide (SMO) gas sensors have attracted widespread attention due to their advantages such as low cost, high sensitivity, portability, and ease of integration. The main disadvantages of SMO gas sensors include high operating temperature (150-400℃) and low selectivity. SMO gas sensors typically exhibit high response and fast response speed at higher operating temperatures (>150℃). At high temperatures, gas sensors generally show similar responses to formaldehyde and other reducing interfering gases. Most SMO gas sensors respond more strongly to ethanol than formaldehyde because ethanol is ubiquitous and its concentration is often higher than formaldehyde. Therefore, ordinary SMO gas sensors cannot effectively distinguish between ethanol and formaldehyde, leading to false alarms. Furthermore, formaldehyde sensing is performed at lower operating temperatures to reduce energy consumption and extend sensor lifespan. Developing a semiconductor metal oxide gas sensor that can selectively detect formaldehyde at low operating temperatures remains a significant challenge. Summary of the Invention
[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing mesoporous silver oxide-tin dioxide nanosphere gas-sensitive materials and their applications. The mesoporous silver oxide-tin dioxide nanosphere gas-sensitive materials prepared by this method can detect formaldehyde gas under low temperature conditions.
[0004] To achieve the above objectives, the preparation method of the mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material of the present invention includes the following steps:
[0005] Mesoporous silver oxide-tin dioxide nanosphere gas-sensitive materials were prepared by a one-step hydrothermal method using tannic acid as a complexing and reducing agent, and stannous sulfate and silver nitrate as metal precursors.
[0006] The mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material is coated on a ceramic tube electrode to detect formaldehyde, with a response time of 44s.
[0007] The mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material has a detection range of 50 ppb-20 ppm for formaldehyde gas.
[0008] The mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material can detect formaldehyde gas at a temperature of 25-125℃.
[0009] The mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material has a detection limit of 23.6 ppb for formaldehyde gas.
[0010] Specifically, the following steps are included:
[0011] Tannic acid was dissolved in a mixed solvent of water and ethanol, the pH was adjusted, formaldehyde was added, and after stirring, stannous sulfate and silver nitrate solution were added and stirred to react. After the reaction was completed, the mixture was subjected to hydrothermal constant temperature, and then the precipitate was collected by centrifugation, dried and calcined to obtain mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material.
[0012] The molar ratio of tin ions in stannous sulfate to silver ions in silver nitrate solution is (10-200):1.
[0013] Adjust the pH to 8-10.
[0014] Application of a mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material in formaldehyde detection.
[0015] The present invention has the following beneficial effects:
[0016] The preparation method and application of the mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material of this invention involves using tannic acid as a complexing and reducing agent, and stannous sulfate and silver nitrate as metal precursors. The mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material is prepared via a one-step hydrothermal method. This material, coated onto a ceramic tube electrode, can be used for formaldehyde detection at low temperatures, with a response time of only 44 seconds. It exhibits good selectivity and anti-interference properties, and the baseline showed no significant drift after 30 days of continuous operation. Experiments show that the mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material prepared by this invention has a formaldehyde gas concentration detection range of 50 ppb (0-20 ppm), a detection temperature of 25-125℃, and a detection limit as low as 23.6 ppb, demonstrating excellent selectivity and anti-interference properties. Attached Figure Description
[0017] Figure 1 (a) is a SEM image of the mesoporous silver oxide-tin dioxide nanospheres prepared in Example 1;
[0018] Figure 1 (b) is a SEM image of the mesoporous silver oxide-tin dioxide nanospheres prepared in Example 2;
[0019] Figure 1 (c) is a SEM image of the mesoporous silver oxide-tin dioxide nanospheres prepared in Example 3;
[0020] Figure 1 (d) is a TEM image of the mesoporous silver oxide-tin dioxide nanospheres prepared in Example 2;
[0021] Figure 1 (e) is a high-resolution TEM image of the mesoporous silver oxide-tin dioxide nanospheres prepared in Example 2;
[0022] Figure 1 (f) is a photograph of the elemental distribution of the mesoporous silver oxide-tin dioxide nanospheres prepared in Example 2;
[0023] Figure 2 (a) is a diagram showing the nitrogen adsorption-desorption process of the mesoporous silver oxide-tin dioxide nanospheres prepared in Examples 1, 2 and 3;
[0024] Figure 2 (b) is a pore size distribution diagram of the mesoporous silver oxide-tin dioxide nanospheres prepared in Examples 1, 2 and 3;
[0025] Figure 3 The XRD patterns are of the mesoporous silver oxide-tin dioxide nanospheres prepared in Examples 1, 2 and 3.
[0026] Figure 4 (a) The response of the mesoporous silver oxide-tin dioxide nanospheres prepared in Examples 1, 2 and 3 to 10 ppm formaldehyde gas at different operating temperatures;
[0027] Figure 4 (b) is a response / recovery time diagram of mesoporous silver oxide-tin dioxide nanospheres prepared in Example 2 at the optimal operating temperature to 10 ppm formaldehyde gas;
[0028] Figure 4 (c) is a repeatable response diagram of mesoporous silver oxide-tin dioxide nanospheres prepared in Example 2 to 10 ppm formaldehyde gas at the optimal operating temperature;
[0029] Figure 4 (de) is the response curve of mesoporous silver oxide-tin dioxide nanospheres prepared in Example 2 at the optimal working temperature to different concentrations of formaldehyde gas;
[0030] Figure 4 (f) is a graph showing the linear relationship between the responses of the mesoporous silver oxide-tin dioxide nanospheres prepared in Example 2 to different concentrations of formaldehyde at the optimal operating temperature.
[0031] Figure 5 (a) is a response diagram of mesoporous silver oxide-tin dioxide nanospheres prepared in Examples 1, 2 and 3 to 10 ppm of different gases;
[0032] Figure 5 (b) is a ratio distribution diagram of the response of the mesoporous silver oxide-tin dioxide nanospheres prepared in Example 2 to 10 ppm formaldehyde and 10 ppm other gases.
[0033] Figure 5 (c) is a graph showing the ratio of the response of the mesoporous silver oxide-tin dioxide nanospheres prepared in Example 2 to 10 ppm formaldehyde + 10 ppm other gases to the response to 10 ppm formaldehyde.
[0034] Figure 5 (d) is a graph showing the ratio of the response of the mesoporous silver oxide-tin dioxide nanospheres prepared in Example 2 to 10 ppm formaldehyde + different concentrations of ethanol gas to the response to 10 ppm formaldehyde.
[0035] Figure 6 This is a SEM image of the mesoporous silver oxide-tin dioxide nanospheres prepared in Example 4. Detailed Implementation
[0036] To enable those skilled in the art to better understand the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, not all embodiments, and are not intended to limit the scope of the present invention. Furthermore, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion regarding the concepts disclosed in the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.
[0037] The accompanying drawings show structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not drawn to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.
[0038] The preparation method of the mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material of the present invention includes the following steps:
[0039] Tannic acid was dissolved in a mixed solvent of water and ethanol, the pH was adjusted to 8-10, formaldehyde was added, and the mixture was stirred for 24 hours. Stannous sulfate and silver nitrate solution were then added and stirred for 12 hours. After the reaction was completed, the mixture was hydrothermally heated at 100℃ for 12 hours. The precipitate was then collected by centrifugation, dried, and calcined for 3 hours to obtain mesoporous silver oxide-tin dioxide nanosphere gas-sensitive materials.
[0040] The molar ratio of tin ions in stannous sulfate to silver ions in silver nitrate solution is (10-200):1.
[0041] The mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material is coated on a ceramic tube electrode to detect formaldehyde, with a response time of 44 s. The detection range of the mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material for formaldehyde gas is 50 ppb-20 ppm. The detection temperature of the mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material for formaldehyde gas is 25-125℃. The detection limit of the mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material for formaldehyde gas is 23.6 ppb, and it has good selectivity and anti-interference ability, with no significant baseline drift after 30 days of continuous operation.
[0042] The application of the mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material prepared in this invention in formaldehyde detection.
[0043] Example 1
[0044] The preparation method of the mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material of the present invention includes the following steps:
[0045] 1) Accurately weigh 0.2g of tannic acid and add it to a mixture of 37mL of ultrapure water and 8mL of anhydrous ethanol. After it is fully dissolved, add 0.35mL of ammonia (25wt%) to adjust the pH to 9.5, and then add 4mL of formaldehyde solution (3.7wt%) to obtain a yellow transparent solution. Stir the reaction for 24h.
[0046] 2) Accurately weigh 0.07 g of SnSO4 and 3 mg of AgNO3, dissolve them completely in 2 mL of ultrapure water, add them to the solution obtained in step 1), and continue stirring for 12 h to obtain Ag / Sn-TA polymer nanospheres;
[0047] 3) The Ag / Sn-TA polymer nanospheres were collected by centrifugation and calcined in a muffle furnace for 3 hours at a temperature of 400℃ to obtain silver oxide-tin dioxide nanospheres.
[0048] 4) The obtained silver oxide-tin dioxide nanospheres were ground with ethanol into a paste. The paste was coated on the alumina electrode tube, which was then calcined at 300°C for 1 hour and aged at 150°C for two days to obtain a semiconductor metal oxide gas sensor for selectively detecting formaldehyde.
[0049] like Figure 1 As shown in Figure a, the silver oxide-tin dioxide nanospheres prepared in this embodiment have a uniform particle size.
[0050] like Figure 2 a and Figure 2 As shown in b, the silver oxide-tin dioxide nanospheres prepared in this embodiment have a high specific surface area and a large pore size.
[0051] like Figure 3 As shown, the XRD diffraction peaks of the silver oxide-tin dioxide nanospheres prepared in this embodiment can be completely matched with SnO2 and Ag2O.
[0052] like Figure 4 As shown in Figure a, the optimal operating temperature for formaldehyde detection of the silver oxide-tin dioxide nanospheres prepared in this embodiment is 75°C, and the response to 10 ppm formaldehyde gas at 75°C is as high as 15.19.
[0053] like Figure 5 As shown in Figure a, the silver oxide-tin dioxide nanospheres prepared in this embodiment show almost no response to gases other than formaldehyde, indicating that they have good selectivity.
[0054] Example 2
[0055] The preparation method of the mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material of the present invention includes the following steps:
[0056] 1) Accurately weigh 0.2g of tannic acid and add it to a mixture of 37mL of ultrapure water and 8mL of anhydrous ethanol. After it is fully dissolved, add 0.35mL of ammonia (25wt%) to adjust the pH to 8.5, and then add 4mL of formaldehyde solution (3.7wt%) to obtain a yellow transparent solution. Stir the reaction for 24h.
[0057] 2) Accurately weigh 0.07 g of SnSO4 and 5 mg of AgNO3, dissolve them completely in 2 mL of ultrapure water, add them to the solution obtained in step 1, and continue stirring for 12 h to obtain Ag / Sn-TA polymer nanospheres;
[0058] 3) The Ag / Sn-TA polymer nanospheres were collected by centrifugation and calcined in a muffle furnace for 3 hours at a temperature of 400℃ to obtain silver oxide-tin dioxide nanospheres.
[0059] 4) The obtained silver oxide-tin dioxide nanospheres were ground with ethanol into a paste. The paste was coated on an alumina electrode tube, which was then calcined at 300°C for 1 hour and aged at 150°C for two days to obtain a semiconductor metal oxide gas sensor for selectively detecting formaldehyde.
[0060] like Figure 1 As shown in b, the silver oxide-tin dioxide nanospheres prepared in this embodiment have a uniform particle size.
[0061] like Figure 2 a and Figure 2 As shown in b, the silver oxide-tin dioxide nanospheres prepared in this embodiment have a high specific surface area and a large pore size.
[0062] like Figure 3 As shown, the XRD diffraction peaks of the silver oxide-tin dioxide nanospheres prepared in this embodiment can be completely matched with SnO2 and Ag2O.
[0063] like Figure 4 As shown in Figure a, the optimal operating temperature for formaldehyde detection of the silver oxide-tin dioxide nanospheres prepared in this embodiment is 75°C, and the response to 10 ppm formaldehyde gas at 75°C is as high as 140.33.
[0064] like Figure 4 As shown in b, the response / recovery times of the silver oxide-tin dioxide nanospheres prepared in this embodiment to 10 ppm formaldehyde are 44 / 222 s, respectively.
[0065] like Figure 4 As shown in c, the silver oxide-tin dioxide nanospheres prepared in this embodiment showed almost no change in baseline and response to 10 ppm formaldehyde in 5 cycles, indicating good repeatability.
[0066] like Figure 4 d and Figure 4 As shown in Figure e, the silver oxide-tin dioxide nanospheres prepared in this embodiment have different responses to formaldehyde gas of different concentrations, and the response gradually increases with the increase of formaldehyde gas concentration.
[0067] like Figure 4 As shown in f, the detection limit of the silver oxide-tin dioxide nanospheres prepared in this embodiment was calculated to be 23.6 ppb.
[0068] like Figure 5 a and Figure 5 As shown in b, the silver oxide-tin dioxide nanospheres prepared in this embodiment exhibit a response to formaldehyde that is 93.34-128.35 times greater than that to other gases, indicating good selectivity.
[0069] like Figure 5 As shown in Figure c, the silver oxide-tin dioxide nanospheres prepared in this embodiment exhibit almost identical responses to 10 ppm formaldehyde and other gases as to 10 ppm formaldehyde gas, indicating good anti-interference properties.
[0070] like Figure 5 As shown in d, the silver oxide-tin dioxide nanospheres prepared in this embodiment showed almost no change in response when different concentrations of ethanol were added to 10 ppm formaldehyde, indicating that they have good resistance to ethanol interference.
[0071] Example 3
[0072] The preparation method of the mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material of the present invention includes the following steps:
[0073] 1) Accurately weigh 0.2g of tannic acid and add it to a mixture of 37mL of ultrapure water and 8mL of anhydrous ethanol. After it is fully dissolved, add 0.35mL of ammonia (25wt%) to adjust the pH to 10, and then add 4mL of formaldehyde solution (3.7wt%) to obtain a yellow transparent solution. Stir the reaction for 24h.
[0074] 2) Accurately weigh 0.07 g of SnSO4 and 10 mg of AgNO3, dissolve them completely in 2 mL of ultrapure water, add them to the solution obtained in step 1, and continue stirring for 12 h to obtain Ag / Sn-TA polymer nanospheres;
[0075] 3) The Ag / Sn-TA polymer nanospheres were collected by centrifugation and calcined in a muffle furnace for 3 hours at a temperature of 400℃ to obtain silver oxide-tin dioxide nanospheres.
[0076] 4) Grind silver oxide-tin dioxide nanospheres with ethanol into a paste, coat the paste onto an alumina electrode tube, calcine the electrode tube at 300℃ for 1 hour, and then age it at 150℃ for two days to obtain a semiconductor metal oxide gas sensor for selectively detecting formaldehyde.
[0077] like Figure 1 As shown in c, the silver oxide-tin dioxide nanospheres prepared in this embodiment have a uniform particle size.
[0078] like Figure 2 a and Figure 2 As shown in b, the silver oxide-tin dioxide nanospheres prepared in this embodiment have a high specific surface area and a large pore size.
[0079] like Figure 3 As shown, the XRD diffraction peaks of the silver oxide-tin dioxide nanospheres prepared in this embodiment can be completely matched with SnO2 and Ag2O.
[0080] like Figure 4 As shown in Figure a, the optimal operating temperature for formaldehyde detection of the silver oxide-tin dioxide nanospheres prepared in this embodiment is 75°C, and the response to 10 ppm formaldehyde at 75°C is as high as 29.38.
[0081] like Figure 5As shown in Figure a, the silver oxide-tin dioxide nanospheres prepared in this embodiment show almost no response to gases other than formaldehyde, indicating that they have good selectivity.
[0082] Example 4
[0083] The preparation method of the mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material of the present invention includes the following steps:
[0084] 1) Accurately weigh 0.2g of tannic acid and add it to a mixture of 37mL of ultrapure water and 8mL of anhydrous ethanol. After it is fully dissolved, add 0.35mL of ammonia (25wt%) to adjust the pH to 8, and then add 4mL of formaldehyde solution (3.7wt%) to obtain a yellow transparent solution. Stir the reaction for 24h.
[0085] 2) Accurately weigh 0.07 g of SnCl2·2H2O and 2 mg of AgNO3, dissolve them completely in 2 mL of ultrapure water, add them to the solution obtained in step 1, and continue stirring for 12 h to obtain Ag / Sn-TA polymer nanospheres;
[0086] 3) The sample was collected by centrifugation and calcined in a muffle furnace for 3 hours at a temperature of 400℃ to obtain silver oxide-tin dioxide nanospheres;
[0087] 4) The obtained silver oxide-tin dioxide nanospheres were ground with ethanol into a paste. The paste was coated on an alumina electrode tube, which was then calcined at 300°C for 1 hour and aged at 150°C for two days to obtain a semiconductor metal oxide gas sensor for selectively detecting formaldehyde.
[0088] like Figure 6 As shown, the silver oxide-tin dioxide nanospheres prepared in this embodiment have a uniform particle size.
[0089] Example 5
[0090] The preparation method of the mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material of the present invention includes the following steps:
[0091] Tannic acid was dissolved in a mixed solvent of water and ethanol, the pH was adjusted to 9.5, formaldehyde was added, and the mixture was stirred for 24 hours. Stannous sulfate and silver nitrate solution were then added, and the mixture was stirred for 12 hours. After the reaction was completed, the mixture was hydrothermally heated at 100°C for 12 hours. The precipitate was then collected by centrifugation, dried, and calcined for 3 hours to obtain mesoporous silver oxide-tin dioxide nanosphere gas-sensitive materials.
[0092] The molar ratio of tin ions in stannous sulfate to silver ions in silver nitrate solution is 150:1.
[0093] Example 6
[0094] The preparation method of the mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material of the present invention includes the following steps:
[0095] Tannic acid was dissolved in a mixed solvent of water and ethanol, the pH was adjusted to 8.5, formaldehyde was added, and the mixture was stirred for 24 hours. Stannous sulfate and silver nitrate solution were then added, and the mixture was stirred for 12 hours. After the reaction was completed, the mixture was hydrothermally heated at 100°C for 12 hours. The precipitate was then collected by centrifugation, dried, and calcined for 3 hours to obtain mesoporous silver oxide-tin dioxide nanosphere gas-sensitive materials.
[0096] The molar ratio of tin ions in stannous sulfate to silver ions in silver nitrate solution is 50:1.
[0097] Example 7
[0098] The preparation method of the mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material of the present invention includes the following steps:
[0099] Tannic acid was dissolved in a mixed solvent of water and ethanol, the pH was adjusted to 9, formaldehyde was added, and the mixture was stirred for 24 hours. Then, stannous sulfate and silver nitrate solution were added and stirred for 12 hours. After the reaction was completed, the mixture was hydrothermally heated at 100°C for 12 hours. The precipitate was then collected by centrifugation, dried, and calcined for 3 hours to obtain mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material.
[0100] The molar ratio of tin ions in stannous sulfate to silver ions in silver nitrate solution is 100:1.
[0101] Example 8
[0102] The preparation method of the mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material of the present invention includes the following steps:
[0103] Tannic acid was dissolved in a mixed solvent of water and ethanol, the pH was adjusted to 10, formaldehyde was added, and the mixture was stirred for 24 hours. Then, stannous sulfate and silver nitrate solution were added and stirred for 12 hours. After the reaction was completed, the mixture was hydrothermally heated at 100°C for 12 hours. The precipitate was then collected by centrifugation, dried, and calcined for 3 hours to obtain mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material.
[0104] The molar ratio of tin ions in stannous sulfate to silver ions in silver nitrate solution is 200:1.
[0105] Example 9
[0106] The preparation method of the mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material of the present invention includes the following steps:
[0107] Tannic acid was dissolved in a mixed solvent of water and ethanol, the pH was adjusted to 8, formaldehyde was added, and the mixture was stirred for 24 hours. Then, stannous sulfate and silver nitrate solution were added and stirred for 12 hours. After the reaction was completed, the mixture was hydrothermally heated at 100°C for 12 hours. The precipitate was then collected by centrifugation, dried, and calcined for 3 hours to obtain mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material.
[0108] The molar ratio of tin ions in stannous sulfate to silver ions in silver nitrate solution is 10:1.
[0109] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.
[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.
Claims
1. A method for preparing a mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material, characterized in that, Includes the following steps: Mesoporous silver oxide-tin dioxide nanosphere gas-sensitive materials were prepared by a one-step hydrothermal method using tannic acid as a complexing and reducing agent, and stannous sulfate and silver nitrate as metal precursors. The mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material can detect formaldehyde gas at a temperature of 25-125℃. Specifically, the following steps are included: Tannic acid was dissolved in a mixed solvent of water and ethanol, the pH value was adjusted, formaldehyde was added, and after stirring for 24 hours, stannous sulfate and silver nitrate solution were added and stirred for 12 hours. After the reaction was completed, the mixture was hydrothermally heated at 100 °C for 12 hours. The precipitate was then collected by centrifugation, dried, and calcined for 3 hours to obtain mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material. The molar ratio of tin ions in stannous sulfate to silver ions in silver nitrate solution is (10-200):1; Adjust the pH to 8-10.
2. The method for preparing the mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material according to claim 1, characterized in that, The mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material is coated on a ceramic tube electrode to detect formaldehyde, with a response time of 44s.
3. The method for preparing the mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material according to claim 1, characterized in that, The mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material has a detection range of 50 ppb-20 ppm for formaldehyde gas.
4. The method for preparing the mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material according to claim 1, characterized in that, The mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material has a detection limit of 23.6 ppb for formaldehyde gas.
5. The application of the mesoporous silver oxide-tin dioxide nanosphere gas-sensitive material prepared according to any one of claims 1 to 4 in formaldehyde detection.