Gas-sensitive sensing material based on SnO2 / SnS2 composite material as well as preparation method and application of gas-sensitive sensing material

Abstract

The invention provides a gas-sensitive sensing material based on a SnO2 / SnS2 composite material as well as a preparation method and application of the gas-sensitive sensing material. The preparation method comprises the following steps: firstly, synthesizing SnO2 nanoflowers consisting of ultrathin nanosheets by using a hydrothermal method, then constructing a SnO2 / SnS2 composite material by using an in-situ high-temperature vulcanization method, and coating an aluminum oxide ceramic tube containing a gold electrode with the composite material. The prepared gas sensitive sensor has the advantages of high sensitivity, good stability and selectivity, and fast response and recovery at room temperature. According to the gas sensitive sensor prepared by the method, the working temperature of a traditional SnO2 gas sensitive sensor can be reduced by utilizing the heterojunction effect, the gas sensitive performance is improved, the response value can reach 80% or above, and the gas sensitive sensor has important research significance and wide application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation and application of semiconductor gas-sensitive sensor materials, and specifically relates to a gas-sensitive sensor material based on SnO2 / SnS2 composite material and a preparation method and application thereof. Background Art

[0002] Chemical warfare agents (CWAs), as highly toxic compounds, pose a huge threat to military personnel and civilians in the modern geopolitical environment. Sarin (GB, isopropyl methylphosphonate) is a nerve agent with excellent stability, rapid action, strong lethality, and long-lasting damage. Therefore, real-time early warning and detection of sarin agents are crucial to protecting human health and environmental safety.

[0003] Among various rapid and portable detection technologies, chemical resistance gas sensors have attracted much attention due to their advantages such as simple operation, low cost, real-time response, and miniaturization. Among them, gas sensors based on metal oxide semiconductors (MOS) have the advantages of simple preparation, high response value, and fast response speed. Tin oxide (SnO2), as an n-type metal oxide semiconductor with a wide band gap (3.6eV), has excellent electrical, optical, and electrochemical properties and has received extensive attention in the detection of sarin agents. Among them, the three-dimensional nanoflower-shaped tin oxide formed by stacking two-dimensional layered nanosheets can not only provide a large specific surface area and provide more active sites for gas reactions on the material surface, but also this petal structure makes the stacked three-dimensional flower-like structure have a larger gap surface, and at the same time exposes more active sites at the edge, thereby providing the possibility for rapid gas adsorption and desorption.

[0004] However, pure tin oxide-based gas sensors have defects such as high operating temperature, slow response time, inability to fully recover, and poor selectivity in the process of detecting sarin. SnS2 is an n-type semiconductor. Since its work function is close to that of SnO2, it is easy for electrons to move between SnO2 and SnS2, which helps to promote the adsorption of surface oxygen, thereby possibly improving the gas sensing performance at low temperatures. Therefore, constructing SnO2 / SnS2 heterojunction nanoflowers is considered to be one of the effective ways to improve gas sensing performance. However, due to the limitations of the preparation process, there are few studies on SnO2 / SnS2 composites in the detection of sarin. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] The present invention provides a gas-sensitive sensing material based on SnO2 / SnS2 composite material and a preparation method and application thereof, so as to solve the technical problem of how to manufacture the gas-sensitive sensing material based on SnO2 / SnS2 composite material conveniently and at low cost.

[0007] (II) Technical solution

[0008] In order to solve the above technical problems, the present invention proposes a method for preparing a gas sensitive sensing material based on SnO2 / SnS2 composite material, a simple hydrothermal method is used to obtain SnO2 nanoflowers composed of ultrathin nanosheets, and then the SnO2 nanoflowers are calcined and sulfurized in a double-temperature zone tubular furnace to obtain a gas sensitive sensing material based on SnO2 / SnS2 composite material.

[0009] Furthermore, the method for preparing the gas sensitive sensor material comprises the following steps:

[0010] S1. Preparation of SnO2 nanoflowers

[0011] Dissolve SnCl2·2H2O and sodium citrate in deionized water and stir; add sodium hydroxide solution to the solution, pour the solution into a polytetrafluoroethylene reactor, heat, and naturally cool to room temperature; centrifuge and wash the obtained product, and dry it under vacuum conditions; calcine the dried product in an air atmosphere to obtain SnO2 nanoflowers;

[0012] Preparation of S2.SnO2 / SnS2

[0013] The sulfur powder and SnO2 nanoflowers are placed at the air inlet and air outlet of a double-temperature zone tubular furnace respectively for calcination and sulfurization; the temperature of the air inlet and air outlet is raised to 180-200°C and 500-600°C; the mixture is naturally cooled to room temperature to obtain a gas sensitive sensing material based on SnO2 / SnS2 composite material.

[0014] Furthermore, the method for preparing the gas sensitive sensor material comprises the following steps:

[0015] S1. Preparation of SnO2 nanoflowers

[0016] Dissolve 0.5-1.0g SnCl2·2H2O and 2.5-3.0g sodium citrate in 10mL deionized water and stir magnetically for 5 minutes; add 8-12mL sodium hydroxide solution dropwise to the above solution, pour the above solution into a 25mL polytetrafluoroethylene reactor, heat at 180-200℃ for 12 hours, and cool naturally to room temperature; centrifuge the obtained product and wash it with acetone and ethanol several times respectively, and dry it under vacuum for 12 hours; calcine the dried product in an air atmosphere at 400-500℃ for 4 hours to obtain SnO2 nanoflowers;

[0017] Preparation of S2.SnO2 / SnS2

[0018] 100-300 mg of sulfur powder and 100 mg of SnO2 nanoflowers are placed at the air inlet and air outlet ends of a double-temperature zone tubular furnace respectively for calcination and sulfurization; the temperatures of the air inlet and air outlet ends are raised to 180-200°C and 500-600°C; the mixture is naturally cooled to room temperature to obtain a gas sensitive sensing material based on SnO2 / SnS2 composite material.

[0019] Furthermore, in step S1, the concentration of the sodium hydroxide solution is 0.2 mol / L.

[0020] Furthermore, in step S2, during the entire calcination and sulfurization process, nitrogen is kept flowing continuously at 0.2 to 0.3 L / min.

[0021] Furthermore, in step S2, within 1 hour, the temperatures of the air inlet end and the air outlet end are respectively raised to 180-200° C. and 500-600° C.

[0022] Furthermore, in step S2, the air inlet end and the air outlet end are maintained at the highest temperature for 0.5 to 1 hour respectively.

[0023] In addition, the present invention also proposes a gas-sensitive sensing material based on SnO2 / SnS2 composite material, which is prepared by the above method. The gas-sensitive sensing material has a nanoflower morphology composed of ultra-thin nanosheets, and the crystal structure is a tetragonal phase crystal structure. SnS2 is distributed on the surface of SnO2, and the crystal structure is a hexagonal crystal system.

[0024] In addition, the present invention also proposes a gas sensor, characterized in that the gas sensor is a gas sensor with a gas-sensitive sensing material based on the SnO2 / SnS2 composite material as a sensing layer, obtained by applying the above-mentioned gas-sensitive sensing material based on the SnO2 / SnS2 composite material to an alumina ceramic tube containing a gold electrode.

[0025] In addition, the present invention also proposes an application of the gas sensor, which uses the gas sensor to quickly detect sarin and its simulant gas under room temperature conditions.

[0026] (III) Beneficial effects

[0027] The present invention proposes a gas-sensitive sensing material based on SnO2 / SnS2 composite material, and a preparation method and application thereof. First, a SnO2 nanoflower composed of ultra-thin nanosheets is synthesized by a hydrothermal method, and then a SnO2 / SnS2 composite material is constructed by an in-situ high-temperature sulfurization method. The composite material is coated on an alumina ceramic tube containing a gold electrode to prepare a gas sensor with high sensitivity, good stability and selectivity, and fast response recovery at room temperature. The gas sensor prepared by this method can utilize the heterojunction effect to reduce the operating temperature of the traditional SnO2 gas sensor, improve the gas-sensitive performance, and the response value can reach more than 80%, which has important research significance and broad application prospects.

[0028] Compared with the prior art, the present invention has the following technical effects:

[0029] 1. The present invention provides a novel preparation method for obtaining SnO2 / SnS2 sensing materials. A simple hydrothermal method is used to obtain SnO2 nanoflowers composed of ultrathin nanosheets, and then the SnO2 nanoflowers are calcined and sulfurized in a double-temperature zone tubular furnace to obtain SnO2 / SnS2 gas-sensitive sensing materials. The method is simple and controllable, low-cost, and has great significance for actual production applications.

[0030] 2. The SnO2 / SnS2 gas-sensitive sensing material prepared by the present invention has the following structural characteristics: the synthesized SnO2 / SnS2 is a three-dimensional nanoflower morphology composed of nanosheets, and the three-dimensional nanoflower has special properties such as small size effect, surface effect, quantum size effect, etc. At the same time, the SnO2 / SnS2 prepared by the present invention has a typical nn-type heterostructure, which can significantly improve the gas-sensitive performance of tin oxide to sarin and its simulant gas through the heterojunction effect.

[0031] 3. The SnO2 / SnS2 gas-sensitive sensing material prepared by the present invention has good response / recovery, high response and selectivity to sarin and its simulants. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 XRD patterns of SnO2 and SnO2 / SnS2;

[0033] Figure 2 It is a scanning electron microscope image of SnO2 / SnS2-200;

[0034] Figure 3 This is a high-resolution transmission electron microscopy image of SnO2 / SnS2-200;

[0035] Figure 4 The dynamic response recovery curve of SnO2 / SnS2-200 based gas sensor to 0.01-2.0ppm concentration of sarin at room temperature;

[0036] Figure 5 This is the dynamic response recovery curve of SnO2 / SnS2-200 based gas sensor to 1.0ppm concentration of sarin at room temperature;

[0037] Figure 6 This is the long-term stability diagram of SnO2 / SnS2-200 based gas sensor sensing 1ppm sarin at room temperature within 30 days;

[0038] Figure 7a This is a scanning electron microscope image of SnO2 / SnS2-300. Figure 7b This is a high-resolution transmission electron microscopy image;

[0039] Figure 8 The response values ​​of SnO2 / SnS2-300 based gas sensors to 1 ppm of different target gases (DMMP, 2-CEES, triethylamine, nitrogen dioxide, sulfur dioxide, hydrogen, ethanol and ammonia) at room temperature;

[0040] Figure 9a This is a scanning electron microscope image of SnO2. Figure 9b High-resolution transmission electron microscopy image. DETAILED DESCRIPTION

[0041] In order to make the purpose, content and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below in conjunction with the drawings and examples.

[0042] Example 1

[0043] SnO2 / SnS2-200 gas sensitive sensing material is prepared and a gas sensor is made. The specific process is as follows:

[0044] S1. 0.9g SnCl2·2H2O and 2.94g sodium citrate were dissolved in 10mL deionized water, magnetically stirred for 5 minutes, and then 10mL sodium hydroxide solution (0.2mol / L) was added dropwise to the above solution, and the above solution was poured into a polytetrafluoroethylene reactor (25mL), and then heated at 180-200°C for 12 hours. After naturally cooling to room temperature, the obtained product was centrifuged and washed several times with acetone and ethanol, respectively, and then dried under vacuum for 12 hours. Finally, the dried product was calcined in an air atmosphere at 400-500°C for 4 hours to obtain SnO2 three-dimensional nanoflowers.

[0045] S2. Place 200 mg of sulfur powder and 100 mg of SnO2 three-dimensional nanoflowers at the air inlet and outlet of a dual-temperature zone tubular furnace for calcination and sulfurization. During the entire sulfurization process, nitrogen is kept flowing continuously (0.2-0.3 L / min). Then, within 1 hour, the temperature of the air inlet and outlet is raised to 180-200°C and 500-600°C, respectively, and the temperature of the two zones is maintained at the highest point for 1 hour. Finally, cool naturally to room temperature to obtain the SnO2 / SnS2-200 composite material.

[0046] A small amount of the prepared SnO2 / SnS2-200 gas sensitive sensing material was placed in a mortar, ethanol was added for grinding, and the material was evenly applied on the alumina ceramic tube electrodes with gold electrodes at both ends to obtain a gas sensor with SnO2 / SnS2-200 gas sensitive sensing material as the sensing layer.

[0047] The X-ray diffraction pattern of SnO2 / SnS2-200 gas-sensitive material is as follows Figure 1 As shown in Figure 1, the sample contains both tetragonal tin oxide and hexagonal tin sulfide, with no diffraction peaks of other impurities. The scanning electron microscope spectrum of SnO2 / SnS2-200 gas-sensitive material is shown in Figure 1. Figure 2 As shown in Figure 2, it can be clearly observed that the prepared SnO2 / SnS2-200 is a three-dimensional nanoflower morphology composed of ultra-thin nanosheets. The high-resolution transmission electron microscopy spectrum of the SnO2 / SnS2-200 gas-sensitive material is shown in Figure 2. Figure 3 As shown in Figure 1, it can be clearly observed that the main exposed crystal planes are the 110 crystal plane of SnO2 and the 101 crystal plane of SnS2. Figure 4 As shown in the figure, the SnO2 / SnS2-200 based gas sensor has a good linear relationship with 0.01-2.0ppm sarin, with the lowest practical detection limit of 10ppb and a response value of 2.8%. The dynamic gas sensing test of SnO2 / SnS2-200 based gas sensor for sarin is shown in the figure. Figure 5 As shown in the figure, under room temperature, the SnO2 / SnS2-200 based gas sensor has a faster response recovery time to 1.0 ppm sarin, which is 7S and 35S respectively, and the response value is 80%. Figure 6 It can be seen that the SnO2 / SnS2-200 based gas sensor has long-term stability.

[0048] Example 2

[0049] SnO2 / SnS2-300 gas sensitive sensing material is prepared and a gas sensor is made. The specific process is as follows:

[0050] S1. 0.9g SnCl2·2H2O and 2.94g sodium citrate were dissolved in 10mL deionized water, magnetically stirred for 5 minutes, and then 10mL sodium hydroxide solution (0.2mol / L) was added dropwise to the above solution, and the solution was poured into a polytetrafluoroethylene reactor (25mL), and then heated at 180-200°C for 12 hours. After naturally cooling to room temperature, the obtained product was centrifuged and washed several times with acetone and ethanol, respectively, and then dried under vacuum conditions for 12 hours. Finally, the dried product was calcined in an air atmosphere at 400-500°C for 4 hours to obtain SnO2 three-dimensional nanoflowers.

[0051] S2. 300 mg of sulfur powder and 100 mg of SnO2 three-dimensional nanoflowers were placed at the air inlet and outlet of a dual-temperature zone tubular furnace for calcination and sulfurization. During the entire sulfurization process, nitrogen was kept flowing continuously (0.2-0.3 L / min). Then, within 1 hour, the temperatures of the air inlet and outlet were raised to 180-200°C and 500-600°C, respectively, and the temperatures of the two zones were kept at the highest point for 1 hour. Finally, the SnO2 / SnS2-300 composite material was obtained by natural cooling to room temperature.

[0052] A small amount of the prepared SnO2 / SnS2-300 gas sensitive sensing material is placed in a mortar, ethanol is added for grinding, and the material is evenly applied on an alumina ceramic tube electrode with gold electrodes at both ends to obtain a gas sensor with the SnO2 / SnS2-300 gas sensitive sensing material as the sensing layer.

[0053] The X-ray diffraction pattern of SnO2 / SnS2-300 gas-sensitive material is as follows Figure 1 As shown in Figure 1, the sample contains both tetragonal tin oxide and hexagonal tin sulfide, with no diffraction peaks of other impurities. The scanning electron microscope image and high-resolution transmission electron microscope image of SnO2 / SnS2-300 gas-sensitive material are shown in Figure 1. Figure 7a and 7b As shown in the figure, it can be clearly observed that the prepared SnO2 / SnS2-200 is a three-dimensional nanoflower morphology composed of ultrathin nanosheets, and the main exposed crystal planes are the 110 crystal plane of SnO2 and the 101 crystal plane of SnS2. Figure 8 It can be seen that under room temperature conditions, the SnO2 / SnS2-300 based gas sensor has good selectivity for DMMP.

[0054] Comparative Example 1

[0055] Preparation of SnO2 nanoflower gas-sensitive sensing materials and production of DMMP gas sensors. The specific process is as follows:

[0056] 0.9g SnCl2·2H2O and 2.94g sodium citrate were dissolved in 10mL deionized water, magnetically stirred for 5 minutes, and then 10mL sodium hydroxide solution (0.2mol / L) was added dropwise to the above solution, and the solution was poured into a polytetrafluoroethylene reactor (25mL), and then heated at 180-200°C for 12 hours. After naturally cooling to room temperature, the obtained product was centrifuged and washed several times with acetone and ethanol, respectively, and then dried under vacuum for 12 hours. Finally, the dried product was calcined in an air atmosphere at 400-500°C for 4 hours to obtain SnO2 three-dimensional nanoflowers.

[0057] A small amount of the prepared SnO2 three-dimensional nanoflower gas-sensitive sensing material is placed in a mortar, ethanol is added to grind it, and it is evenly applied on the alumina ceramic tube electrodes with gold electrodes at both ends to obtain a gas sensor with the SnO2 gas-sensitive sensing material as the sensing layer.

[0058] The X-ray diffraction pattern of SnO2 three-dimensional nanoflower gas-sensitive material is shown in Figure 1 As shown in Figure 2, the sample is a tetragonal crystal system with no diffraction peaks of other impurities. The scanning electron microscope image and high-resolution transmission electron microscope image of SnO2 gas-sensitive material are shown in Figure 2. Figure 9a and 9b As shown in the figure, it can be clearly observed that the prepared SnO2 is a three-dimensional nanoflower morphology composed of ultrathin nanosheets, and the main exposed crystal plane is the 110 crystal plane. At room temperature, the SnO2-based gas sensor has no response to DMMP.

[0059] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a gas-sensitive sensing material based on SnO2 / SnS2 composite material, characterized in that: The gas-sensitive sensor material preparation method adopts a simple hydrothermal method to obtain SnO2 nanoflowers composed of ultra-thin nanosheets, and then calcines and sulfurizes the SnO2 nanoflowers in a double-temperature zone tubular furnace to obtain a gas-sensitive sensor material based on a SnO2 / SnS2 composite material.

2. The method for preparing a gas-sensitive sensor material based on a SnO2 / SnS2 composite material according to claim 1, characterized in that: The method for preparing the gas sensitive sensor material comprises the following steps: S1. Preparation of SnO2 nanoflowers Dissolve SnCl2·2H2O and sodium citrate in deionized water and stir; add sodium hydroxide solution to the solution, pour the solution into a polytetrafluoroethylene reactor, heat, and naturally cool to room temperature; centrifuge and wash the obtained product, and dry it under vacuum conditions; calcine the dried product in an air atmosphere to obtain SnO2 nanoflowers; Preparation of S2.SnO2 / SnS2 The sulfur powder and SnO2 nanoflowers are placed at the air inlet and air outlet of a double-temperature zone tubular furnace respectively for calcination and sulfurization; the temperature of the air inlet and air outlet is raised to 180-200°C and 500-600°C; the mixture is naturally cooled to room temperature to obtain a gas sensitive sensing material based on SnO2 / SnS2 composite material.

3. The method for preparing a gas-sensitive sensor material based on a SnO2 / SnS2 composite material according to claim 2, characterized in that: The method for preparing the gas sensitive sensor material comprises the following steps: S1. Preparation of SnO2 nanoflowers Dissolve 0.5-1.0g SnCl2·2H2O and 2.5-3.0g sodium citrate in 10mL deionized water and stir magnetically for 5 minutes; add 8-12mL sodium hydroxide solution dropwise to the above solution, pour the above solution into a 25mL polytetrafluoroethylene reactor, heat at 180-200℃ for 12 hours, and cool naturally to room temperature; centrifuge the obtained product and wash it with acetone and ethanol several times respectively, and dry it under vacuum for 12 hours; calcine the dried product in an air atmosphere at 400-500℃ for 4 hours to obtain SnO2 nanoflowers; Preparation of S2.SnO2 / SnS2 100-300 mg of sulfur powder and 100 mg of SnO2 nanoflowers are placed at the air inlet and air outlet ends of a double-temperature zone tubular furnace respectively for calcination and sulfurization; the temperatures of the air inlet and air outlet ends are raised to 180-200°C and 500-600°C; the mixture is naturally cooled to room temperature to obtain a gas sensitive sensing material based on SnO2 / SnS2 composite material.

4. The method for preparing a gas-sensitive sensor material based on a SnO2 / SnS2 composite material according to claim 3, characterized in that: In step S1, the concentration of the sodium hydroxide solution is 0.2 mol / L.

5. The method for preparing a gas-sensitive sensor material based on a SnO2 / SnS2 composite material according to claim 3, characterized in that: In step S2, during the entire calcination and sulfurization process, nitrogen is kept flowing continuously at 0.2 to 0.3 L / min.

6. The method for preparing a gas-sensitive sensor material based on a SnO2 / SnS2 composite material according to claim 3, characterized in that: In step S2, within 1 hour, the temperature of the air inlet end and the air outlet end are respectively increased to 180-200° C. and 500-600° C.

7. The method for preparing a gas-sensitive sensor material based on a SnO2 / SnS2 composite material according to claim 3, characterized in that: In step S2, the air inlet end and the air outlet end are respectively maintained at the highest temperature for 0.5 to 1 hour.

8. A gas-sensitive sensing material based on SnO2 / SnS2 composite material, characterized in that: The gas-sensitive sensing material is prepared by the method described in any one of claims 1 to 7. The gas-sensitive sensing material has a nanoflower morphology composed of ultra-thin nanosheets, a tetragonal crystal structure, SnS2 distributed on the surface of SnO2, and a hexagonal crystal structure.

9. A gas sensor, characterized in that: The gas sensor is obtained by applying the gas-sensitive sensing material based on the SnO2 / SnS2 composite material as claimed in claim 8 onto an alumina ceramic tube containing a gold electrode to obtain a gas sensor with the gas-sensitive sensing material based on the SnO2 / SnS2 composite material as the sensing layer.

10. An application of the gas sensor according to claim 9, characterized in that: The gas sensor is used to quickly detect sarin and its simulant gas under room temperature conditions.

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