Preparation method and application of tin disulfide / indium oxide heterojunction

Abstract

A preparation method and application of a tin disulfide / indium oxide heterojunction, and relates to the technical field of gas sensor material preparation. The purpose of the present invention is to solve the problem that most traditional nitrogen dioxide sensors cannot be used to work at room temperature, or the nitrogen dioxide gas sensors used for room temperature detection have large volume and low sensitivity. Method: Add SnS2 to anhydrous ethanol, stir evenly, then add indium nitrate hydrate, continue stirring for 1 to 2 hours, and then ultrasonicate for 0.1 to 10 minutes after the stirring is completed to obtain solution a, heat solution a to 150 to 180°C, and hydrothermally react for 5 to 10 hours, cool after the reaction is completed, collect the precipitate after the reaction and wash it, and dry it after washing to obtain a tin disulfide / indium oxide heterojunction. The present invention can obtain a preparation method and application of a tin disulfide / indium oxide heterojunction.

Description

Technical Field

[0001] The invention relates to the technical field of gas sensor material preparation, and in particular to a preparation method of a tin disulfide / indium oxide heterojunction and application thereof. Background Art

[0002] With the rapid development of modern industry, energy-based industrial growth consumes a large amount of fossil fuels, and the emission of atmospheric pollutants is also increasing year by year, leading to the continuous aggravation of environmental pollution and global warming. In addition to producing a large amount of greenhouse gas-carbon dioxide, the combustion of fossil fuels also produces a large amount of nitrogen oxides. Among them, NO 2 It is the most common and largest type of nitrogen oxide. 2 It is a toxic gas. A large amount of NO in the air 2 The presence of NO will cause natural disasters such as acid rain, which will cause trees to die, birds and animals to become extinct, the land to crack, and a large area of ​​land to be lifeless. It will also damage our living environment, dissolve concrete, reduce the strength of buildings, and threaten our living safety. In addition, NO 2 It is also one of the main causes of photochemical smog. Excessive NO inhalation by the human body 2 The gas can cause pulmonary edema, which can cause instant death in severe cases. 2 Therefore, it is necessary to strictly control and reduce NO 2 Gas emissions. But traditional NO 2 Many sensors cannot work at room temperature, or the NO 2 Gas sensors have disadvantages such as large size and low sensitivity. Therefore, the development and research of NO 2 Gas sensors can help detect NO 2 Effectively control gas emissions. Summary of the invention

[0003] The purpose of the present invention is to solve the traditional NO 2 Most sensors cannot work at room temperature, or are used for NO detection at room temperature. 2 Gas sensors have the problems of large size and low sensitivity, and a preparation method of a tin disulfide / indium oxide heterojunction and its application are provided.

[0004] A method for preparing a tin disulfide / indium oxide heterojunction is carried out according to the following steps:

[0005] SnS 2 Add to anhydrous ethanol, stir evenly, then add indium nitrate hydrate, continue stirring for 1 to 2 hours, and then ultrasonicate for 0.1 to 10 minutes after the stirring is completed to obtain solution a, SnS 2The molar ratio of the tin disulfide to indium nitrate hydrate is 0.05:(0.1-1); the solution a is heated to 150-180° C., and a hydrothermal reaction is carried out at a temperature of 150-180° C. for 5-10 hours. After the reaction is completed, the solution is cooled, and the precipitate after the reaction is collected and washed, and then dried to obtain a tin disulfide / indium oxide heterojunction.

[0006] Application of a tin disulfide / indium oxide heterojunction, wherein the tin disulfide / indium oxide heterojunction is used to prepare NO 2 Gas sensor.

[0007] Principle of the present invention:

[0008] The present invention is due to In 2 O 3 SnS 2 When forming a heterojunction, In 2 O 3 The Fermi level of SnS 2 , making In 2 O 3 The electrons are transferred to SnS 2 , improve SnS 2 conductivity, thereby achieving room temperature NO 2 At the same time, due to the formation of the heterojunction, the NO 2 The adsorbed active sites ultimately improve the sensing sensitivity.

[0009] Beneficial effects of the present invention:

[0010] (1) The present invention successfully prepared SnS by a one-step hydrothermal method. 2 / In 2 O 3 Heterojunction, which is prepared into NO 2 Gas sensor for NO at room temperature 2 Gas detection, the sensor is 1ppm NO at 25℃ 2 The sensitivity of the gas is as high as 2610%, and the detection limit can reach 0.25ppm, while SnS 2 andIn 2 O 3 None of them can independently achieve NO 2 Highly sensitive detection of gases.

[0011] The SnS prepared in the present invention 2 / In 2 O 3 Heterojunction, with high sensitivity and good repeatability, and good selectivity and long-term stability, is SnS 2 / In 2 O 3Heterojunction for commercial production of NO 2 Gas sensors provide the possibility of being used for NO 2 Industrial production of gas detection, while avoiding the traditional NO 2 Most sensors cannot work at room temperature, or the NO 2 Gas sensors have disadvantages such as large size and low sensitivity.

[0012] (2) SnS prepared by the present invention 2 / In 2 O 3 Heterojunctions for the preparation of NO 2 Gas sensors can be used for detection of boiler flue gas before emission and monitoring of nitrogen oxide content in the atmospheric environment.

[0013] The invention can obtain a preparation method of a tin disulfide / indium oxide heterojunction and application thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The SnS prepared in Example 1 2 / In 2 O 3 SEM image of the heterojunction.

[0015] Figure 2 The SnS prepared in Example 1 2 / In 2 O 3 XRD pattern of heterojunction, a represents In 2 O 3 , b represents SnS 2 / In 2 O 3 , c represents SnS 2 .

[0016] Figure 3 The SnS prepared in Example 1 2 / In 2 O 3 The heterojunction reacts with different concentrations of NO at room temperature. 2 Dynamic response curve.

[0017] Figure 4 The SnS prepared in Example 1 2 / In 2 O 3 Selectivity test diagram of heterojunction for different gases.

[0018] Figure 5 The SnS prepared in Example 1 2 / In 2 O 3Heterojunction to 0.5ppm NO 2 Long-term stability test chart. DETAILED DESCRIPTION

[0019] Specific implementation method 1: In this implementation method, a method for preparing a tin disulfide / indium oxide heterojunction is carried out according to the following steps:

[0020] SnS 2 Add to anhydrous ethanol, stir evenly, then add indium nitrate hydrate, continue stirring for 1 to 2 hours, and then ultrasonicate for 0.1 to 10 minutes after the stirring is completed to obtain solution a, SnS 2 The molar ratio of the tin disulfide to indium nitrate hydrate is 0.05:(0.1-1); the solution a is heated to 150-180° C., and a hydrothermal reaction is carried out at a temperature of 150-180° C. for 5-10 hours. After the reaction is completed, the solution is cooled, and the precipitate after the reaction is collected and washed, and then dried to obtain a tin disulfide / indium oxide heterojunction.

[0021] Specific implementation method 2: This implementation method is different from the specific implementation method 1 in that: SnS 2 Add into anhydrous ethanol and stir with a magnetic stirrer until uniform.

[0022] The other steps are the same as those in the first specific implementation.

[0023] Specific implementation method 3: This implementation method is different from specific implementation method 1 or 2 in that: SnS 2 The ratio of the amount of substance to the volume of anhydrous ethanol is 0.05mmol:(20~40)mL.

[0024] The other steps are the same as those in the first or second embodiment.

[0025] Specific embodiment 4: The difference between this embodiment and specific embodiments 1 to 3 is that solution a is transferred to the inner lining of the reaction kettle and heated to 150-180°C.

[0026] The other steps are the same as those in Specific Embodiments 1 to 3.

[0027] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that solution a is heated to 170-180° C. and subjected to hydrothermal reaction at 170-180° C. for 5-6 hours.

[0028] The other steps are the same as those in Specific Embodiments 1 to 4.

[0029] Specific implementation method 6: The difference between this implementation method and specific implementation methods 1 to 5 is that the precipitate after the reaction is collected, first washed with ultrapure water for 3 to 5 times, and then washed with ethanol for 3 to 5 times.

[0030] The other steps are the same as those in Specific Embodiments 1 to 5.

[0031] Specific embodiment 7: The difference between this embodiment and specific embodiments 1 to 6 is that after cleaning, the mixture is dried at 60 to 80° C. for 10 to 12 hours to obtain a tin disulfide / indium oxide heterojunction.

[0032] The other steps are the same as those in Specific Embodiments 1 to 6.

[0033] Specific embodiment 8: The tin disulfide / indium oxide heterojunction described in this embodiment is used to prepare NO 2 Gas sensor.

[0034] The following examples are used to verify the beneficial effects of the present invention:

[0035] Example 1: A method for preparing a tin disulfide / indium oxide heterojunction is carried out according to the following steps:

[0036] 1. Take a 50mL beaker, first use a 50mL measuring cylinder to weigh 32mL of anhydrous ethanol and pour it into the 50mL beaker, then use an electronic balance to weigh 0.05mmol SnS 2 Pour into a beaker and stir well on a magnetic stirrer.

[0037] 2. After the above solution is stirred evenly, add 0.25 mmol of indium nitrate hydrate and continue stirring for 1 hour. After stirring, ultrasonicate for 1 minute to completely dissolve the residual drugs at the bottom and wall of the beaker due to the evaporation of alcohol to obtain solution a.

[0038] 3. Transfer 32 mL of solution a to the inner lining of a 40 mL reactor, heat to 180 °C, and perform hydrothermal reaction at 180 °C for 6 h.

[0039] 4. After the reactor is cooled, collect the precipitate after the reaction, wash it with ultrapure water for 3 times, then wash it with ethanol for 3 times, and finally dry it at 60°C for 12 hours to obtain a tin disulfide / indium oxide heterojunction.

[0040] The SnS obtained by the method of Example 1 2 / In 2 O 3 Heterojunction, its scanning electron microscope Figure 1 As shown, we can see SnS 2 / In 2 O 3 The heterojunction forms a flower-like structure of about 3 μm, most of which is In 2 O 3 Nanospheres are distributed in SnS 2 To further prove that SnS 2 / In2 O 3 The successful synthesis of the heterojunction has a great impact on SnS 2 / In 2 O 3 Heterojunction, pure phase SnS 2 and Chun Sang In 2 O 3 XRD tests were carried out respectively, and the results are as follows Figure 2 As shown, SnS 2 / In 2 O 3 SnS can be seen in the heterojunction 2 andIn 2 O 3 The characteristic peaks of SnS indicate the successful synthesis of the heterostructure. 2 andIn 2 O 3 The unrelated peaks further illustrate the obtained SnS 2 / In 2 O 3 The heterojunction has no impurities.

[0041] The SnS prepared in this example 2 / In 2 O 3 The heterojunction gas-sensitive material was dissolved in acetone and ultrasonicated for 10 min to obtain SnS 2 / In 2 O 3 The heterojunction dispersion is SnS 2 / In 2 O 3 The heterojunction dispersion is dropped onto the surface of the pre-prepared Ag-Pd electrode sheet. After the acetone solvent evaporates, SnS 2 / In 2 O 3 Heterojunction materials can form a uniform film on the electrode surface and can be directly used to test the sensing of NO 2 performance.

[0042] Testing SnS by electrochemical workstation 2 / In 2 O 3 The performance of heterojunction-based gas sensors, sensitivity is defined as: Response (%) = (R g -R a ) / R a ×100, where R a is the resistance of the sensor in air, R g is the resistance value of the sensor in the gas to be tested. The test results are as follows Figure 3As shown, the test results show that at room temperature, the SnS 2 / In 2 O 3 Gas sensors prepared by heterojunction gas-sensitive materials adsorb NO 2 After the gas is released, the resistance value of the sensor will increase significantly, and with the increase of NO 2 As the concentration increases, the sensitivity of the sensor also increases significantly. At the same time, the gas sensor also has good selectivity, such as Figure 4 As shown, for 10 ppm interfering gas (H 2 S. NH 3 and CH 4 ) had almost no response, but to 0.5 ppm NO 2 The sensitivity can reach 162%.

[0043] In summary, the SnS obtained in this embodiment 2 / In 2 O 3 Heterojunction for the preparation of NO 2 Gas sensors have the characteristics of high sensitivity and good repeatability, as well as good selectivity and long-term stability. They are suitable for NO 2 Industrial production of gas detection.

Claims

1. A method for preparing a tin disulfide / indium oxide heterojunction for preparing a NO2 gas sensor, characterized in that The preparation method is carried out according to the following steps: SnS2 is added to anhydrous ethanol, stirred evenly, and then indium nitrate hydrate is added, and stirring is continued for 1 to 2 hours. After the stirring is completed, ultrasonication is performed for 0.1 to 10 minutes to obtain solution a, and the molar ratio of SnS2 to indium nitrate hydrate is 0.05:0.25; solution a is heated to 180°C, and hydrothermally reacted at 180°C for 6 hours, and then cooled after the reaction is completed, and the precipitate after the reaction is collected and washed, and then dried after washing to obtain a tin disulfide / indium oxide heterojunction; the tin disulfide / indium oxide heterojunction is used to prepare a NO2 gas sensor.

2. The method for preparing a tin disulfide / indium oxide heterojunction for preparing a NO2 gas sensor according to claim 1, characterized in that Add SnS2 into anhydrous ethanol and stir with a magnetic stirrer until uniform.

3. A method for preparing a tin disulfide / indium oxide heterojunction for preparing a NO2 gas sensor according to claim 1 or 2, characterized in that The ratio of the amount of SnS2 to the volume of anhydrous ethanol is 0.05mmol:(20~40)mL.

4. The method for preparing a tin disulfide / indium oxide heterojunction for preparing a NO2 gas sensor according to claim 1, characterized in that The precipitate after the reaction was collected, and washed with ultrapure water for 3 to 5 times, and then washed with ethanol for 3 to 5 times.

5. The method for preparing a tin disulfide / indium oxide heterojunction for preparing a NO2 gas sensor according to claim 1, characterized in that After cleaning, the mixture is dried at 60 to 80° C. for 10 to 12 hours to obtain a tin disulfide / indium oxide heterojunction.

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