Molybdenum disulfide / zinc stannate composite material and preparation method and application thereof
The molybdenum disulfide nanosheets prepared by lysine-assisted ball milling peeling method are compounded with zinc stannate to form an n-n heterojunction, which solves the problems of high working temperature and low sensitivity of existing gas-sensitive materials, and realizes high-sensitivity room temperature ammonia detection.
Patent Information
- Application Number
- CN202510321041.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-18
- Publication Date
- 2025-06-13
AI Technical Summary
The existing gas-sensitive materials for detecting ammonia gas have problems of high operating temperature requirements and low sensitivity.
Molybdenum disulfide nanosheets were prepared by lysine-assisted ball milling peeling method and composited with zinc stannate to form an n-n heterojunction to improve gas-sensitive performance.
It realizes high sensitivity ammonia detection under room temperature conditions, improving the performance and stability of the gas-sensitive sensor.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention belongs to the field of gas sensing materials and their preparation, and particularly relates to a molybdenum disulfide / zinc stannate composite material, a preparation method thereof, and an application thereof. Background Art
[0002] Ammonia is toxic, flammable and explosive, and has a strong pungent smell. It is reported that exposure to 25 ppm of ammonia for 8 hours will have harmful effects on human health. Even a small amount of ammonia can cause irreparable damage to human skin, eyes, respiratory system and mucous membranes, and even cause death in extreme cases. Therefore, it is particularly important to develop a flexible sensor with sensing performance for room temperature ammonia.
[0003] Gas sensing materials are the core components of gas sensors. The most promising gas sensing materials for manufacturing flexible and wearable gas sensing devices are two-dimensional (2D) semiconductor nanomaterials. Among them, molybdenum disulfide has been widely used as a gas sensing material due to its unique graphene-like layered structure, rich surface active sites and tunable bandgap. However, previous studies have found that molybdenum disulfide has many deficiencies, such as: the existence of weak van der Waals forces between molybdenum disulfide layers makes it easy for molybdenum disulfide nanosheets to agglomerate and disperse unevenly, thus affecting its performance; untreated single molybdenum disulfide performs relatively poorly in terms of sensitivity, working temperature, etc.
[0004] In order to improve the performance of gas sensors, researchers have proposed various strategies such as defect modulation, heterostructure construction, noble metal nanoparticle modification and morphology control, etc., to reduce the coverage of the environment on molybdenum disulfide nanosheets and improve the gas sensing performance of molybdenum disulfide. Among them, constructing a heterostructure by combining a metal oxide semiconductor and molybdenum disulfide nanosheets can generate an electronic effect, which can significantly improve the gas sensing performance of molybdenum disulfide.
[0005] Previously, a single metal oxide semiconductor and molybdenum disulfide nanosheets were combined to construct a heterostructure to improve the gas sensing performance. However, single metal oxide semiconductors such as tin oxide, zinc oxide, etc., have a relatively simple electronic structure and are prone to phase change or degradation at high temperature or during long-term use. After being combined with molybdenum disulfide nanosheets, although the gas sensing performance can be improved, its sensitivity is low and its stability is poor, etc. Summary of the Invention
[0006] In order to solve the problems such as high working temperature requirements and low sensitivity existing in the existing gas sensing materials for detecting ammonia, the present invention provides a molybdenum disulfide / zinc stannate composite material, a preparation method thereof, and an application thereof.
[0007] The present invention is realized through the following technical solutions: In the first aspect, the present invention provides a preparation method of a molybdenum disulfide / zinc stannate composite material, including: S1: Using lysine as a ball-milling aid, ball-mill molybdenum disulfide. After ball-milling, perform solid-liquid separation, wash the obtained solid, then add it to a solvent and ultrasonicate. Centrifuge and take the supernatant, and freeze-dry the supernatant to obtain molybdenum disulfide nanosheets; S2: Add molybdenum disulfide nanosheets and zinc stannate to a mixed solution of water and ethanol, ultrasonically disperse, and perform solid-liquid separation to obtain a molybdenum disulfide / zinc stannate composite material.
[0008] Preferably, in S1, the mass ratio of molybdenum disulfide to lysine is 1:(1 - 5).
[0009] Preferably, in S1, the ball-milling speed is 450 - 650 rpm.
[0010] Preferably, in S1, the ball-milling time is 6 - 12 hours.
[0011] Preferably, in S1, the ultrasonic time is 1 - 5 hours.
[0012] Preferably, in S2, the mass ratio of molybdenum disulfide nanosheets to zinc stannate is (3 - 1):1.
[0013] Preferably, in S2, the mass ratio of water to ethanol is 1:(1 - 5).
[0014] In a second aspect, the present invention provides a molybdenum disulfide / zinc stannate composite material obtained by the described preparation method.
[0015] In a third aspect, the present invention provides a gas sensor, including a gas-sensitive sensing layer, and the gas-sensitive material on the gas-sensitive sensing layer is the described molybdenum disulfide / zinc stannate composite material.
[0016] In a second aspect, the present invention provides the application of the described molybdenum disulfide / zinc stannate composite material or the described gas sensor in ammonia detection.
[0017] Compared with the prior art, the present invention has the following beneficial effects: The present invention prepares molybdenum disulfide nanosheets by using lysine-assisted ball milling exfoliation method. By utilizing the physical shear force during the ball milling and ultrasonic processes, the weak van der Waals force between the layers of molybdenum disulfide is overcome, promoting the lateral exfoliation of molybdenum disulfide. The amino and carboxyl functional groups in lysine attach to the surface or edges of molybdenum disulfide, forming stable chemical bond connections, functionalizing molybdenum disulfide, thereby improving the dispersion stability of molybdenum disulfide nanosheets and obtaining few-layer molybdenum disulfide nanosheets. Molybdenum disulfide nanosheets have a natural bandgap and a high carrier mobility, and there are a large number of unsaturated bonds at the edges that can serve as reactive sites; zinc stannate is an n-type semiconductor double metal oxide with a perovskite structure. Compared with zinc oxide and tin oxide, it has the characteristics of strong conductivity, a high electron mobility, and a matching transition of the electronic structure; the molybdenum disulfide nanosheets are combined with zinc stannate to form an n-n heterojunction. The formation of the n-n heterojunction enhances the response to ammonia of molybdenum disulfide. This is because when the sensor is exposed to the reducing gas ammonia, a large number of electrons are released into the conduction band, resulting in the contraction of the electron depletion region, an increase in the carrier concentration, and a decrease in the resistance, thereby enhancing the response. The decrease in the sensor resistance when exposed to a reducing gas is a characteristic of n-type semiconductor materials. The synergistic effect of the combination of molybdenum disulfide nanosheets and zinc stannate can provide a large number of active sites that are beneficial for the adsorption and desorption of ammonia molecules, effectively improving the sensitivity of the molybdenum disulfide / zinc stannate composite material to the target gas ammonia.
[0018] The gas-sensitive sensor prepared from the composite material of the present invention has a high sensitivity at room temperature, realizes the deviceization of the flexible gas-sensitive sensor, and expands the application field of flexible sensor devices. Detailed implementation manners
[0019] The following specific examples illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.
[0020] It should be noted that the process equipment or devices not specifically noted in the following examples all adopt conventional equipment or devices in the art.
[0021] It should be noted that the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units need not be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, rather than limiting the arrangement order of each method step or the scope in which the present invention can be implemented. The change or adjustment of their relative relationship, without substantial change in the technical content, should also be regarded as the scope in which the present invention can be implemented.
[0022] The preparation method of the molybdenum disulfide / zinc stannate composite material described in the present invention includes: S1. Using lysine as a ball-milling aid, ball-mill molybdenum disulfide. After ball-milling, perform solid-liquid separation. Wash the obtained solid, then add it to a solvent and ultrasonicate. Centrifuge and take the upper clear liquid, and freeze-dry the upper clear liquid to obtain molybdenum disulfide nanosheets; S2. Add the molybdenum disulfide nanosheets and zinc stannate to a mixed solution of water and ethanol, ultrasonically disperse, and perform solid-liquid separation to obtain the molybdenum disulfide / zinc stannate composite material.
[0023] The present invention uses lysine-assisted ball-milling exfoliation method to prepare molybdenum disulfide nanosheets. Utilize the physical shear force during ball-milling and ultrasonication to overcome the weak van der Waals force between the layers of molybdenum disulfide, and promote the lateral exfoliation of molybdenum disulfide. The amino and carboxyl functional groups in lysine attach to the surface or edge of molybdenum disulfide to form stable chemical bond connections, functionalize molybdenum disulfide, thereby improving the dispersion stability of molybdenum disulfide nanosheets and obtaining few-layer molybdenum disulfide nanosheets. The molybdenum disulfide nanosheets prepared by the lysine-assisted ball-milling exfoliation method show a typical few-layer structure and have a high specific surface area, which is beneficial to promoting the adsorption of the alkaline gas ammonia on its surface and subsequent gas-sensing reactions. At the same time, the molybdenum disulfide nanosheets and zinc stannate are compounded to construct a gas-sensing material. Their synergistic effect can provide more sufficient space and more active sites for the adsorption of gas molecules, and improve the gas-sensing performance of the gas-sensing material.
[0024] In some embodiments of the present invention, in S1, the mass ratio of molybdenum disulfide to lysine is 1:(1 - 5).
[0025] In some embodiments of the present invention, in S1, the ball-milling speed is 450 - 650 rpm, more preferably 650 rpm; the ball-milling time is 6 - 12 hours, more preferably 12 hours. The greater the ball-milling speed and the longer the ball-milling time, the more beneficial it is to reduce the size of molybdenum disulfide nanosheets and increase the specific surface area of molybdenum disulfide nanosheets, and thus more beneficial to improving the gas-sensing performance.
[0026] In some embodiments of the present invention, in S1, the solvent used is a mixed solution of water and ethanol, the ultrasonic power is 300 - 800 W, and the ultrasonic time is 1 - 5 hours; the centrifugation speed is 2000 - 4000 rpm, and the time is 20 - 60 minutes. The aggregated and thick nanosheets are removed by centrifugation, and small-sized molybdenum disulfide nanosheets are retained.
[0027] In some embodiments of the present invention, in S2, the mass ratio of molybdenum disulfide nanosheets to zinc stannate is (3 - 1):1.
[0028] In some embodiments of the present invention, in S2, the mass ratio of water to ethanol is 1:(1 - 5).
[0029] The gas sensor prepared by using the molybdenum disulfide / zinc stannate composite material of the present invention for monitoring ammonia has high sensitivity, low operating temperature, and is green and environmentally friendly.
[0030] All chemical drugs and reagents in the present invention are of analytical pure grade and are not further purified.
[0031] Example 1 The molybdenum disulfide nanosheets provided in this example are prepared as follows: Using the lysine-assisted ball milling exfoliation method, bulk molybdenum disulfide and lysine are transferred to a 500 mL ball milling jar with zirconia balls of different sizes at a mass ratio of 1:3. The mixture is ball milled at 450 rpm for 3 hours using a planetary ball mill. After ball milling, the product is collected, washed several times by centrifugation and suction filtration with water and ethanol, ultrasonicated at 600 W for 2 h, then centrifugally washed 3 times with water and ethanol respectively to remove the aggregated and thick nanosheets. The supernatant is collected, and part of the sample is dried overnight in a freeze dryer to obtain molybdenum disulfide nanosheets.
[0032] Example 2 The molybdenum disulfide nanosheets provided in this example are prepared as follows: Using the lysine-assisted ball milling exfoliation method, bulk molybdenum disulfide and lysine are transferred to a 500 mL ball milling jar with zirconia balls of different sizes at a mass ratio of 1:1. The mixture is ball milled at 450 rpm for 6 hours using a planetary ball mill. After ball milling, the product is collected, washed several times by centrifugation and suction filtration with water and ethanol, ultrasonicated at 600 W for 1 h, then centrifugally washed 3 times with water and ethanol respectively to remove the aggregated and thick nanosheets. The supernatant is collected, and part of the sample is dried overnight in a freeze dryer to obtain molybdenum disulfide nanosheets.
[0033] Example 3 The molybdenum disulfide nanosheets provided in this example are prepared as follows: Using the lysine-assisted ball milling exfoliation method, bulk molybdenum disulfide and lysine were transferred to a 500 mL ball milling jar with zirconia balls of different sizes at a mass ratio of 1:5. The mixture was ball milled at 650 rpm for 6 hours using a planetary ball mill. After ball milling, the product was collected, washed several times by centrifugation and suction filtration with water and ethanol, sonicated at 600 W for 3 h, and then centrifugally washed 3 times with water and ethanol respectively to remove agglomerated and thick nanosheets. The supernatant was collected, and part of the sample was dried overnight in a freeze dryer to obtain molybdenum disulfide nanosheets.
[0034] Example 4 The molybdenum disulfide nanosheets provided in this example were prepared as follows: Using the lysine-assisted ball milling exfoliation method, bulk molybdenum disulfide and lysine were transferred to a 500 mL ball milling jar with zirconia balls of different sizes at a mass ratio of 1:3. The mixture was ball milled at 450 rpm for 9 hours using a planetary ball mill. After ball milling, the product was collected, washed several times by centrifugation and suction filtration with water and ethanol, sonicated at 600 W for 4 h, and then centrifugally washed 3 times with water and ethanol respectively to remove agglomerated and thick nanosheets. The supernatant was collected, and part of the sample was dried overnight in a freeze dryer to obtain molybdenum disulfide nanosheets.
[0035] Example 5 The molybdenum disulfide nanosheets provided in this example were prepared as follows: Using the lysine-assisted ball milling exfoliation method, bulk molybdenum disulfide and lysine were transferred to a 500 mL ball milling jar with zirconia balls of different sizes at a mass ratio of 1:3. The mixture was ball milled at 450 rpm for 12 hours using a planetary ball mill. After ball milling, the product was collected, washed several times by centrifugation and suction filtration with water and ethanol, sonicated at 600 W for 5 h, and then centrifugally washed 3 times with water and ethanol respectively to remove agglomerated and thick nanosheets. The supernatant was collected, and part of the sample was dried overnight in a freeze dryer to obtain molybdenum disulfide nanosheets.
[0036] Example 6 The molybdenum disulfide nanosheets provided in this example were prepared as follows: Using the lysine-assisted ball milling exfoliation method, bulk molybdenum disulfide and lysine were transferred to a 500 mL ball milling jar with zirconia balls of different sizes at a mass ratio of 1:3. The mixture was ball milled at 650 rpm for 12 hours using a planetary ball mill. After ball milling, the product was collected, washed several times by centrifugation and suction filtration with water and ethanol, sonicated at 600 W for 2 h, and then centrifugally washed 3 times with water and ethanol respectively to remove agglomerated and thick nanosheets. The supernatant was collected, and part of the sample was dried overnight in a freeze dryer to obtain molybdenum disulfide nanosheets.
[0037] Comparative Example 1 The molybdenum disulfide nanosheets provided in this comparative example were prepared as follows: Using the ball milling exfoliation method, bulk MoS 2 was transferred to a 500 mL ball milling jar with zirconia balls of different sizes, and ball milled for 12 hours at a speed of 450 rpm using a planetary ball mill. After ball milling, the product was collected, washed several times by centrifugation and suction filtration with water and ethanol, sonicated for 2 h at 600 W, and then centrifugally washed 3 times with water and ethanol respectively to remove agglomerated and thick nanosheets. The supernatant was collected, and part of the sample was dried overnight in a freeze dryer to obtain molybdenum disulfide nanosheets.
[0038] Taking the non-addition of lysine-assisted ball milling as a blank sample and comparing it with the addition of lysine-assisted ball milling, the test results are shown in Table 1. It can be seen from Table 1 that when using the lysine-assisted ball milling exfoliation method to prepare molybdenum disulfide nanosheets, different ball milling aids, ball milling times, and ball milling speeds will all affect the size and specific surface area of molybdenum disulfide nanosheets. With the changes in ball milling aids, ball milling times, and ball milling speeds, the size and specific surface area of molybdenum disulfide nanosheets have changed greatly. Among them, the size of bulk molybdenum disulfide has been exfoliated from the micron scale to the nanoscale, and the increase in specific surface area helps to promote the adsorption of alkaline gas ammonia on the surface of the gas-sensitive material and subsequent gas-sensitive reactions.
[0039] Table 1
[0040] Example 7 The molybdenum disulfide / zinc stannate composite material provided in this example was prepared as follows: Using the lysine-assisted ball milling exfoliation method, bulk molybdenum disulfide and lysine were transferred to a 500 mL ball milling jar with zirconia balls of different sizes at a mass ratio of 1:3, and the mixture was ball milled for 12 hours at a speed of 650 rpm using a planetary ball mill. After ball milling, the product was collected, washed several times by centrifugation and suction filtration with water and ethanol, sonicated for 2 h at 600 W, and then centrifugally washed 3 times with water and ethanol respectively to remove agglomerated and thick nanosheets. The supernatant was collected, and part of the sample was dried overnight in a freeze dryer to obtain molybdenum disulfide nanosheets. The molybdenum disulfide nanosheets and zinc stannate prepared by hydrothermal method were mixed at a mass ratio of 1:1, dispersed by mechanical stirring and sonication in a mixed solution of 5 mL of deionized water and ethanol (the volume ratio of deionized water to ethanol is 1:1), and then the molybdenum disulfide / zinc stannate composite material obtained in the mixed solution was deposited on the surface of cellulose paper to form a gas-sensitive sensing layer.
[0041] The molybdenum disulfide / zinc stannate composite material of Example 7 was used to prepare a gas sensor, and then the prepared gas sensor was placed at room temperature to detect ammonia at different concentrations. The results are shown in Table 2. As can be seen from Table 2, when the ammonia concentration is 150 ppm, the sensitivity is as high as 9.356. It can be observed that the gas sensor has good response and recovery characteristics to ammonia at room temperature, with high sensitivity and good repeatability; where the sensitivity S = ΔR / R a , ΔR is the difference between the resistance of the gas sensor in the ammonia atmosphere and the initial resistance.
[0042] Table 2
[0043] Example 8 The molybdenum disulfide / zinc stannate composite material provided in this example is prepared as follows: Using lysine-assisted ball milling exfoliation method, bulk molybdenum disulfide and lysine were transferred to a 500 mL ball milling jar with zirconia balls of different sizes at a mass ratio of 1:3, and the mixture was ball milled at 650 rpm for 12 hours using a planetary ball mill. After ball milling, the product was collected, washed several times by centrifugation and suction filtration with water and ethanol, sonicated at 600 W for 2 h, and then centrifuged and washed 3 times with water and ethanol respectively to remove agglomerated and thick nanosheets. The supernatant was collected, and part of the sample was dried overnight in a freeze dryer to obtain molybdenum disulfide nanosheets. The molybdenum disulfide nanosheets and zinc stannate prepared by hydrothermal method were mixed at a mass ratio of 2:1, dispersed by mechanical stirring and sonication in a mixture of 5 mL of deionized water and ethanol (the volume ratio of deionized water to ethanol is 1:5), and then the molybdenum disulfide / zinc stannate composite material obtained in the mixture was deposited on the surface of cellulose paper to form a gas sensing layer.
[0044] The molybdenum disulfide / zinc stannate composite material of Example 8 was used to prepare a gas sensor, and then the prepared gas sensor was placed at room temperature to detect ammonia at different concentrations. The results are shown in Table 3. As can be seen from Table 3, when the ammonia concentration is 150 ppm, the sensitivity is as high as 11.667. It can be observed that the gas sensor has good response and recovery characteristics to ammonia at room temperature; where the sensitivity S = ΔR / R a , ΔR is the difference between the resistance of the gas sensor in the ammonia atmosphere and the initial resistance.
[0045] Table 3
[0046] Example 9 The molybdenum disulfide / zinc stannate composite material provided in this example is prepared as follows: Using the lysine-assisted ball milling exfoliation method, bulk molybdenum disulfide and lysine were transferred to a 500 mL ball milling jar with zirconia balls of different sizes at a mass ratio of 1:3. The mixture was ball milled at 650 rpm for 12 hours using a planetary ball mill. After ball milling, the product was collected and washed several times by centrifugation and suction filtration with water and ethanol, sonicated at 600 W for 2 h, and then centrifuged and washed 3 times with water and ethanol respectively to remove agglomerated and thick nanosheets. The supernatant was collected, and part of the sample was dried overnight in a freeze dryer to prepare molybdenum disulfide nanosheets. The molybdenum disulfide nanosheets and zinc stannate prepared by the hydrothermal method were mixed at a mass ratio of 3:1, dispersed by mechanical stirring and sonication in a mixture of 5 mL of deionized water and ethanol (the volume ratio of deionized water to ethanol was 1:2), and then the molybdenum disulfide / zinc stannate composite material obtained in the mixture was deposited on the surface of cellulose paper to form a gas-sensing layer.
[0047] The molybdenum disulfide / zinc stannate composite material of Example 9 was used to prepare a gas sensor, and then the prepared gas sensor was placed at room temperature to detect ammonia at different concentrations. The results are shown in Table 4. It can be seen from Table 4 that when the ammonia concentration is 150 ppm, the sensitivity is as high as 10.436, and it can be observed that the gas sensor has good response and recovery characteristics to ammonia at room temperature; where the sensitivity S = ΔR / R a , and ΔR is the difference between the resistance of the gas sensor in the ammonia atmosphere and the initial resistance.
[0048] Table 4
[0049] Comparative Example 2 The molybdenum disulfide gas-sensing material provided in this comparative example was prepared as follows: Using the lysine-assisted ball milling exfoliation method, bulk molybdenum disulfide and lysine were transferred to a 500 mL ball milling jar with zirconia balls of different sizes at a mass ratio of 1:3. The mixture was ball milled at 650 rpm for 12 hours using a planetary ball mill. After ball milling, the product was collected and washed several times by centrifugation and suction filtration with water and ethanol, sonicated at 600 W for 2 h, and then centrifuged and washed 3 times with water and ethanol respectively to remove agglomerated and thick nanosheets. The supernatant was collected, and part of the sample was dried overnight in a freeze dryer to prepare molybdenum disulfide nanosheets. The molybdenum disulfide nanosheets were dispersed by mechanical stirring and sonication in a mixture of 5 mL of deionized water and ethanol (the volume ratio of deionized water to ethanol was 1:1), and then the molybdenum disulfide obtained in the mixture was deposited on the surface of cellulose paper to form a gas-sensing layer.
[0050] The molybdenum disulfide nanosheets of Comparative Example 2 were used as the gas-sensitive material to prepare a gas-sensitive sensor, and then the prepared gas-sensitive sensor was placed at room temperature to detect ammonia at different concentrations. The results are shown in Table 5. It can be seen from Table 5 that when the ammonia concentration is 150 ppm, the sensitivity is only 3.338, which is much lower than that of the gas-sensitive sensor prepared with the molybdenum disulfide / zinc stannate composite material of Example 7, indicating that the introduction of zinc stannate can significantly improve the response of the gas-sensitive sensor to ammonia. Among them, the sensitivity S = ΔR / R a , where ΔR is the difference between the resistance of the gas-sensitive sensor in the ammonia atmosphere and the initial resistance.
[0051] Table 5
[0052] Comparative Example 3 The molybdenum disulfide / zinc oxide composite material provided in this comparative example was prepared as follows: Using the lysine-assisted ball milling and exfoliation method, bulk molybdenum disulfide and lysine were transferred to a 500 mL ball milling jar with zirconia balls of different sizes at a mass ratio of 1:3, and the mixture was ball milled at 650 rpm for 12 hours using a planetary ball mill. After ball milling, the product was collected, washed several times by centrifugation and suction filtration with water and ethanol, sonicated at 600 W for 2 h, and then centrifuged and washed 3 times with water and ethanol respectively to remove the agglomerated and thick nanosheets. The supernatant was collected, and part of the sample was dried overnight in a freeze dryer to obtain molybdenum disulfide nanosheets. The molybdenum disulfide nanosheets and zinc oxide were mixed at a mass ratio of 3:1, dispersed in a mixture of 5 mL of deionized water and ethanol (the volume ratio of deionized water to ethanol is 1:2) by mechanical stirring and sonication, and then the molybdenum disulfide / zinc oxide composite material obtained in the mixture was deposited on the surface of cellulose paper to form a gas-sensitive sensing layer.
[0053] The molybdenum disulfide / zinc oxide composite material of Comparative Example 3 was used to prepare a gas-sensitive sensor, and then the prepared gas-sensitive sensor was placed at room temperature to detect ammonia at different concentrations. The results are shown in Table 6. When the ammonia concentration is 150 ppm, the sensitivity is only 5.648, which is lower than that of the gas-sensitive sensor prepared with the molybdenum disulfide / zinc stannate composite material of Example 9, indicating that compounding molybdenum disulfide with zinc stannate to construct a gas-sensitive material can effectively improve the gas-sensitive performance through their synergistic effect.
[0054] Table 6
[0055] Comparative Example 4 The molybdenum disulfide / zinc stannate composite material provided in this comparative example was prepared as follows: Using the ball milling and exfoliation method, bulk MoS 2Transfer to a 500 mL ball milling jar with zirconia balls of different sizes, and ball mill for 12 hours at a speed of 650 rpm using a planetary ball mill. After ball milling, collect the product, wash it several times by centrifugation and suction filtration with water and ethanol, ultrasonicate for 2 h at 600 W, then centrifuge and wash with water and ethanol three times respectively to remove the agglomerated and thick nanosheets, collect the supernatant, dry part of the sample overnight in a freeze dryer to obtain molybdenum disulfide nanosheets. Mix the molybdenum disulfide nanosheets and zinc stannate in a mass ratio of 2:1, disperse them in a mixture of 5 mL of deionized water and ethanol (the volume ratio of deionized water to ethanol is 1:5) by mechanical stirring and ultrasonication, and then deposit the molybdenum disulfide / zinc stannate composite material obtained in the mixture onto the surface of cellulose paper to form a gas-sensitive sensing layer.
[0056] Prepare a gas sensor with the molybdenum disulfide / zinc stannate composite material of Comparative Example 4, and then place the prepared gas sensor at room temperature to detect ammonia gas at different concentrations. The results are shown in Table 7. When the ammonia gas concentration is 150 ppm, the sensitivity is only 5.883, which is lower than that of the gas sensor prepared with the molybdenum disulfide / zinc stannate composite material of Example 8, indicating that the molybdenum disulfide nanosheets prepared by the lysine-assisted ball milling exfoliation method have a higher specific surface area, which is beneficial to promoting the adsorption of the alkaline gas ammonia on its surface and subsequent gas-sensitive reactions.
[0057] Table 7
[0058] In the present invention, the molybdenum disulfide nanosheets prepared by the lysine-assisted ball milling exfoliation method have a higher specific surface area, which is beneficial to promoting the adsorption of the alkaline gas ammonia on its surface and subsequent gas-sensitive reactions. Construct a gas-sensitive material by combining molybdenum disulfide nanosheets with stannic acid. The synergistic effect of the two can provide more sufficient space and more active sites for the adsorption of gas molecules, and improve the gas-sensitive performance of the gas-sensitive material. The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.
Claims
1. A method for preparing a molybdenum disulfide / zinc stannate composite material, characterized in that: include: S1, using lysine as a ball milling aid to ball mill molybdenum disulfide, performing solid-liquid separation after ball milling, washing the obtained solid, then adding it to a solvent and ultrasonicating it, centrifuging to obtain a supernatant, and freeze-drying the supernatant to obtain molybdenum disulfide nanosheets; S2, adding molybdenum disulfide nanosheets and zinc stannate into a mixture of water and ethanol, ultrasonically dispersing, and performing solid-liquid separation to obtain a molybdenum disulfide / zinc stannate composite material.
2. The method for preparing the molybdenum disulfide / zinc stannate composite material according to claim 1, characterized in that: In S1, the mass ratio of molybdenum disulfide to lysine is 1:(1~5).
3. The method for preparing the molybdenum disulfide / zinc stannate composite material according to claim 1, characterized in that: In S1, the ball milling speed is 450~650rpm.
4. The method for preparing the molybdenum disulfide / zinc stannate composite material according to claim 1, characterized in that: In S1, the ball milling time is 6 to 12 hours.
5. The method for preparing the molybdenum disulfide / zinc stannate composite material according to claim 1, characterized in that: In S1, the ultrasound time was 1 to 5 hours.
6. The method for preparing the molybdenum disulfide / zinc stannate composite material according to claim 1, characterized in that: In S2, the mass ratio of molybdenum disulfide nanosheets and zinc stannate is (3~1):
1.
7. The method for preparing the molybdenum disulfide / zinc stannate composite material according to claim 1, characterized in that: In S2, the mass ratio of water to ethanol is 1:(1~5).
8. A molybdenum disulfide / zinc stannate composite material obtained by the preparation method according to any one of claims 1 to 7.
9. A gas sensor, characterized in that: It comprises a gas-sensitive sensing layer, wherein the gas-sensitive material on the gas-sensitive sensing layer is the molybdenum disulfide / zinc stannate composite material as claimed in claim 9.
10. Use of the molybdenum disulfide / zinc stannate composite material according to claim 9 or the gas sensor according to claim 9 in ammonia detection.