Preparation method of tin dioxide porous nanomaterial and hydrogen sensor
By using porous nanomaterials in tin dioxide as the sensing film of hydrogen sensors, the problems of low sensitivity and long response time of existing hydrogen sensors are solved, and the hydrogen detection effect with high sensitivity, fast response and low power consumption is achieved.
Patent Information
- Application Number
- CN202311183976.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-09-13
- Publication Date
- 2025-03-14
AI Technical Summary
The existing semiconductor metal oxide material hydrogen sensors have the disadvantages of low sensitivity, long response and reply time, making it difficult to effectively detect trace amounts of hydrogen at room temperature, especially in the presence of a variety of interfering gases.
A tin dioxide porous nanomaterial was used as a sensing film, and a tin dioxide porous nanomaterial with a high specific surface area and two-dimensional nanostructure was prepared as a sensing film for a hydrogen sensor by reacting a mixture containing tin compounds, potassium halides, and hydrochloric acid until the solution was completely evaporated and annealed.
The high sensitivity, fast response and good response reversibility of the hydrogen sensor are achieved, and trace amounts of hydrogen can be effectively detected at room temperature and in the presence of a variety of interfering gases. The sensor has low power consumption and good portability.
Smart Images
Figure CN119612581A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to a preparation method of a porous tin dioxide nanomaterial and a hydrogen sensor, belonging to the technical field of gas sensors. Background Art
[0002] Hydrogen is a potential clean energy source and is gradually becoming a substitute for traditional energy. In addition, hydrogen is also a good industrial raw material. About 60% of the world's hydrogen is used in the synthetic ammonia industry. Industrial hydrogen is mainly produced from natural gas and water gas. The potential threat of hydrogen as a flammable and explosive gas cannot be ignored. Since hydrogen has a very small ignition point energy and a wide range of explosion limits in the air, it is necessary to monitor the concentration of this gas.
[0003] Hydrogen is a highly flammable and explosive gas, especially when the concentration in the air exceeds 4%, it will form an explosive mixture. The manufacture of hydrogen sensors can be used to monitor potential hydrogen leaks, so as to detect and take measures early to ensure the safety of production facilities, storage facilities and other related environments. To this end, people have conducted a lot of research on different types of equipment in an attempt to obtain hydrogen sensors with high sensitivity and good stability. Hydrogen chemical gas sensors based on metal oxide semiconductors have the advantages of low manufacturing cost, simple operation, high sensitivity, good stability, and good compatibility with technology, and have broad application prospects.
[0004] Existing hydrogen sensors made of semiconductor metal oxide materials have the disadvantages of low sensitivity and long response and recovery time. Summary of the invention
[0005] In order to solve the above problems, the purpose of the present invention is to provide a hydrogen sensor with high selectivity and high sensitivity, and with good response recovery and repeatability, which can meet the detection needs of trace hydrogen at room temperature and in the presence of multiple interfering gases.
[0006] The hydrogen sensor based on tin dioxide porous nanomaterials in this application has high sensitivity and good stability, greatly reduces the power consumption during the use of the sensor, and improves the portability of the sensor. It has important practical and research value in this technical field.
[0007] According to one aspect of the present application, a method for preparing a porous tin dioxide nanomaterial is provided, the preparation method comprising:
[0008] A mixture containing tin compounds, potassium halide, hydrochloric acid and a solvent is reacted until the solution in the mixture is completely evaporated and annealed to obtain the tin dioxide porous nanomaterial.
[0009] Optionally, the tin compound is selected from stannous chloride and / or stannic chloride.
[0010] Optionally, the potassium halide is selected from potassium chloride and / or potassium bromide.
[0011] Optionally, the concentration of the hydrochloric acid is 1-12M.
[0012] Optionally, the concentration of the hydrochloric acid is selected from any value of 1M, 2M, 5M, 7M, 10M, 12M or a range between any two of the above.
[0013] Optionally, the solvent is ethanol and freshly prepared hydrochloric acid.
[0014] Optionally, the solvent is selected from at least one of ethanol, ethanol, water and methanol.
[0015] Optionally, the mass ratio of the tin compound to the potassium halide is 1:2-10.
[0016] Optionally, the mass ratio of the tin compound to the potassium halide is selected from any value of 1:2, 1:4, 1:5, 1:7, 1:10 or a range between any two of the above values.
[0017] Optionally, the volume ratio of the ethanol to the hydrochloric acid is 1:1-2.
[0018] Optionally, the tin compound can be completely dissolved in ethanol, and potassium chloride can be completely dissolved in hydrochloric acid.
[0019] Optionally, the mass volume ratio of the tin compound to hydrochloric acid is 1:60-360.
[0020] Optionally, the reaction temperature is 50-70° C., and the reaction time is 8-12 h.
[0021] Optionally, the reaction temperature is selected from any value of 50°C, 55°C, 60°C, 65°C, 70°C or a range between any two of the above values.
[0022] Optionally, the reaction time is selected from any value among 8h, 9h, 10h, 11h, 12h or a range between any two of the above.
[0023] Optionally, the annealing temperature is 300-500° C., and the annealing time is 1-3 hours.
[0024] Optionally, the annealing temperature is selected from any value of 300° C., 350° C., 400° C., 450° C., 500° C., or a range between any two of the above values.
[0025] Optionally, a water removal treatment is performed before the annealing.
[0026] According to another aspect of the present application, a porous tin dioxide nanomaterial prepared by the preparation method described above is provided, wherein the porous tin dioxide nanomaterial is a two-dimensional nanostructure;
[0027] The specific surface area of the tin dioxide porous nanomaterial is 200 to 700 m 2 / g;
[0028] The diameter of the tin dioxide porous nano material is 500-2000nm.
[0029] Optionally, the diameter of the porous tin dioxide nanomaterial is selected from any value of 500 nm, 1000 nm, 1500 nm, 2000 nm, or a range between any two of the above points.
[0030] According to another aspect of the present application, a hydrogen sensor is provided, the hydrogen sensor comprising a sensing membrane, the sensing membrane comprising a tin dioxide porous nanomaterial;
[0031] The tin dioxide porous nanomaterial is selected from the tin dioxide porous nanomaterials described above.
[0032] Optionally, the sensing film has a thickness of 10 to 2000 nm.
[0033] Optionally, the thickness of the sensing film is selected from any value of 10 nm, 100 nm, 500 nm, 1000 nm, 2000 nm or a range between any two of the above points.
[0034] Optionally, the operating relative humidity of the hydrogen sensor is 25-75%.
[0035] As a specific implementation, the present invention is implemented by the following technical solutions:
[0036] A hydrogen sensor with nanomaterial as sensing membrane consists of a sensing membrane, an electrode pair, a heating resistor wire, and an insulating substrate. The electrode pair is fixed on the surface of the insulating substrate, the sensing membrane is covered on the electrode pair and the insulating substrate between the electrode pairs, the heating resistor wire is located inside the insulating substrate and is externally connected to a DC power supply to control the test temperature, and the electrode pair is provided with leads for transmitting electrical signals. The sensing membrane is a porous tin dioxide nanomaterial.
[0037] Optionally, the relative humidity of the working environment ranges from 25 to 75%.
[0038] The method for preparing the sensing film of the hydrogen sensor comprises the following steps:
[0039] (1) A certain amount of stannous chloride dihydrate and potassium chloride are dissolved in the same volume of anhydrous ethanol and freshly prepared 1M hydrochloric acid, respectively, and the mass ratio of stannous chloride dihydrate to potassium chloride is 1:2-10;
[0040] (2) After being fully mixed, react in an oil bath at 50-70° C. for 8-12 hours until the solution is completely evaporated;
[0041] (3) After removing water from the reaction product, annealing is performed at 300-500°C for 1 hour.
[0042] The present invention uses a film made of porous tin dioxide nanomaterial as a sensitive element, and coats the sensitive element on a ceramic substrate with electrodes printed on the surface to obtain a resistive thin film hydrogen sensor; the sensor signal is the change in the resistance value of the porous tin dioxide nanomaterial film under air and hydrogen gas atmosphere with air as the background.
[0043] The porous tin dioxide nanomaterial has a high specific surface area due to its two-dimensional nanostructure, and the porous morphology further increases its specific surface area. The porous tin dioxide nanomaterial of the present invention can be conveniently fixed on an electrode pair and a substrate, and a sensor is constructed by coating.
[0044] The beneficial effects of this application include:
[0045] 1) The tin dioxide porous nanomaterial provided in the present application has a fine two-dimensional nanostructure and a large specific surface area, which enables the sensor to have high sensitivity, rapid response and good response reversibility.
[0046] 2) Compared with traditional semiconductor gas sensors, the hydrogen sensor of the present invention can fix the sensing film on the electrode pair and the substrate by simple methods (such as drop coating, spin coating, etc.). The film forming method is simple and has good processability, which is conducive to processing on electrodes of different shapes, solving the problem that traditional gas sensors require high-temperature sintering and complex processing.
[0047] 3) The sensor provided in this application can work under simple DC power supply heating conditions, the sensor power consumption is very small, and the sensor is relatively small as a whole, and has the advantage of being portable. BRIEF DESCRIPTION OF THE DRAWINGS
[0048] Figure 1 This is the dynamic response curve of the sensor in Example 2 of the present application to hydrogen at room temperature.
[0049] Figure 2 This is the curve of the response of the sensor to hydrogen at room temperature as the gas concentration changes in Example 2 of the present application.
[0050] Figure 3This is the response curve of the sensor in Example 2 of the present application to 10 ppm hydrogen at 240°C.
[0051] Figure 4 This is a line graph of the response of the sensor in Example 2 of the present application to 10 ppm hydrogen at temperatures ranging from 200 to 300°C.
[0052] Figure 5 These are scanning electron microscope images of the porous tin dioxide nanomaterial in Example 1 of the present application (A: scanning electron microscope image of the porous tin dioxide nanomaterial, scale is 500 nm; B: scanning electron microscope image of the porous tin dioxide nanomaterial, scale is 1.0 um). DETAILED DESCRIPTION
[0053] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.
[0054] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.
[0055] In the examples of the present application, a field emission scanning electron microscope instrument is used to perform scanning electron microscopy characterization on the porous nanomaterial.
[0056] Example 1
[0057] The preparation of a porous tin dioxide nanomaterial sensing membrane comprises the following steps: adding 0.5 g of stannous chloride dihydrate to 36 ml of an ethanol solution, adding 5 g of potassium chloride to 36 ml of a newly prepared 1M hydrochloric acid, stirring and ultrasonically oscillating the two solutions to fully mix them, reacting in an oil bath at 60° C. and stirring until the solution is completely evaporated to dryness, annealing a reaction product at 330° C. in a tube furnace for 1 hour, and centrifuging the reaction product to remove water to obtain a porous tin dioxide nanomaterial. Figure 5 It can be seen that the prepared tin dioxide porous nanomaterials are in the form of uneven sheets and are stacked together, with diameters ranging from 500 to 2000 nm and a thickness of about 100 nm.
[0058] Example 2 Construction of Hydrogen Sensor
[0059] A hydrogen sensor is composed of a sensing film, an electrode, a heating resistance wire, and an insulating substrate. The insulating substrate is made of ceramic, is cylindrical, and has a size of 4 mm×1.2 mm. The electrode is a gold electrode. The sensing film is the tin dioxide nanomaterial prepared in Example 1. The gold electrode is fixed on the surface of the ceramic substrate, the sensing film is coated on the ceramic substrate, the heating resistance wire is located inside the insulating substrate and is externally connected to a DC power supply to control the test temperature, and a wire is provided on the gold electrode for transmitting an electrical signal.
[0060] The porous tin dioxide nanomaterial prepared in Example 1 was drop-coated on the surface of the ceramic tube, and the sensing film thickness was 100 nm. A room temperature hydrogen sensor based on the porous tin dioxide nanomaterial was obtained.
[0061] Sensor testing: A digital multimeter was used to measure the changes in the resistance of the sensor in air and in a hydrogen atmosphere with air as the background at concentrations of 0.2ppm, 0.5ppm, 1ppm, 2ppm, 5ppm, 10ppm, and 15ppm, respectively, as the sensor signal.
[0062] The dynamic response curves of the hydrogen sensor to 0.2ppm, 0.5ppm, 1ppm, 2ppm, 5ppm, 10ppm, and 15ppm hydrogen concentrations at room temperature are shown in FIG. Figure 1 It can be seen that the sensor has a significant and rapid response to different concentrations of hydrogen.
[0063] The response sensitivity curves of the hydrogen sensor to 0.2ppm, 0.5ppm, 1ppm, 2ppm, 5ppm, 10ppm, and 15ppm hydrogen concentrations at room temperature are shown in FIG. Figure 2 It can be seen that the sensor has a high response sensitivity to low concentration hydrogen at room temperature, reaching 17.80 for 10ppm hydrogen, and has a good linear response to hydrogen.
[0064] The response curve of the hydrogen sensor made of porous tin dioxide nanomaterials to 10 ppm hydrogen at 240 °C is shown in Figure 3 It can be seen that at this temperature, the sensor has a good response value and a fast response speed.
[0065] Comparison of hydrogen response values of prepared tin dioxide porous nanomaterials at 200-300℃ Figure 4 It can be seen that the developed sensor exhibits the best response to hydrogen at 240 °C.
[0066] Example 3
[0067] 0.1 g of stannous chloride dihydrate was added to 30 ml of ethanol solution, and 1 g of potassium chloride was added to 30 ml of freshly prepared 1 M hydrochloric acid. The two solutions were stirred and ultrasonically oscillated to be fully mixed. The mixture was stirred in an oil bath at 50° C. until the solution was completely evaporated. The reaction product was annealed at 330° C. in a tube furnace for 1 hour. The reaction product was centrifuged to remove water to obtain a porous tin dioxide nanomaterial.
[0068] Example 4
[0069] A hydrogen sensor was constructed according to the hydrogen sensor in Example 2, and the sensing membrane was replaced with the tin dioxide nanomaterial prepared in Example 3. The material was fixed by drop coating, and the thickness of the sensing membrane was 100 nm. The response sensitivity of the hydrogen sensor to 10 ppm hydrogen was tested to be 13.01.
[0070] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.
Claims
1. A method for preparing a porous tin dioxide nanomaterial, characterized in that: The preparation method comprises: A mixture containing tin compounds, potassium halide, hydrochloric acid and a solvent is reacted until the solution in the mixture is completely evaporated and annealed to obtain the tin dioxide porous nanomaterial.
2. The preparation method according to claim 1, characterized in that: The tin compound is selected from stannous chloride and / or stannic chloride; Preferably, the potassium halide is selected from potassium chloride and / or potassium bromide; Preferably, the concentration of the hydrochloric acid is 1 to 12 M; Preferably, the solvent is selected from at least one of ethanol, water and methanol.
3. The preparation method according to claim 1, characterized in that: The mass ratio of the tin compound to the potassium halide is 1:2-10; Preferably, the volume ratio of ethanol to hydrochloric acid is 1:1-2; Preferably, the mass volume ratio of the tin compound to hydrochloric acid is 1:60-360.
4. The preparation method according to claim 1, characterized in that: The reaction temperature is 50-70° C., and the reaction time is 8-12 hours.
5. The preparation method according to claim 1, characterized in that: The annealing temperature is 300-500° C., and the annealing time is 1-3 hours.
6. The preparation method according to claim 1, characterized in that: The water removal treatment is first performed before the annealing.
7. The porous tin dioxide nanomaterial prepared by the preparation method according to any one of claims 1 to 6, characterized in that: The tin dioxide porous nanomaterial is a two-dimensional nanostructure; The specific surface area of the tin dioxide porous nanomaterial is 200 to 700 m 2 / g; The diameter of the tin dioxide porous nano material is 500-2000nm.
8. A hydrogen sensor, characterized in that: The hydrogen sensor comprises a sensing membrane, and the sensing membrane comprises a porous nanomaterial of tin dioxide; The tin dioxide porous nanomaterial is selected from the tin dioxide porous nanomaterial according to claim 7.
9. The hydrogen sensor according to claim 8, characterized in that: The thickness of the sensing film is 10 to 2000 nm.
10. The hydrogen sensor according to claim 8, characterized in that: The operating relative humidity of the hydrogen sensor is 25-75%.