Gas-sensitive material, preparation method and application thereof, and gas-sensitive component

Abstract

The preparation method comprises the following steps: adding stannic chloride, sodium hydroxide and polyvinylpyrrolidone into absolute ethyl alcohol and deionized water, stirring, adding a chloroauric acid solution, uniformly stirring and mixing to obtain a mixed solution, carrying out a hydrothermal reaction on the mixed solution, and drying to obtain the gas-sensitive material. The preparation method comprises the following steps: adding an Au / SnO2 solution into a hydrothermal reaction kettle, carrying out hydrothermal reaction, cooling to obtain a hydrothermal product, carrying out solid-liquid separation on the hydrothermal product, washing the solid obtained by solid-liquid separation to obtain a precipitate, drying the precipitate, calcining, and cooling to room temperature to obtain the Au / SnO2 gas sensitive material. The Au / SnO2 gas sensitive material is prepared by doping metal Au into SnO2, so that the sensitivity and selectivity of the gas sensitive material are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of gas-sensitive materials, and in particular to a gas-sensitive material and a preparation method, application and gas-sensitive component thereof. Background Art

[0002] Heart disease is one of the leading causes of death worldwide, and early non-invasive testing is needed to assess the condition and risk. Trace amounts of carbon monoxide exhaled by heart disease patients have become a potential biomarker.

[0003] At present, the gas-sensitive materials used in gas sensors for detecting carbon monoxide have low sensitivity in practical applications, which affects the detection performance of the gas sensor.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0005] The technical task of the present invention is to provide a gas-sensitive material and its preparation method, application and gas-sensitive component in view of the above shortcomings. By doping metal Au into SnO2 to prepare Au / SnO2 gas-sensitive material, the sensitivity of the gas-sensitive material is improved, thereby solving the above problems.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] According to one aspect of the present application, a method for preparing a gas-sensitive material is provided, comprising:

[0008] Add tin tetrachloride, sodium hydroxide and polyvinyl pyrrolidone to anhydrous ethanol and deionized water, stir, add chloroauric acid solution, stir and mix to obtain a mixed solution; subject the mixed solution to a hydrothermal reaction, cool after the hydrothermal reaction to obtain a hydrothermal product; separate the hydrothermal product into a solid and a liquid, wash the solid separated from the solid and the liquid to obtain a precipitate; dry and calcine the precipitate, and cool to room temperature to obtain an Au / SnO2 gas-sensitive material.

[0009] In some embodiments, the tin tetrachloride is tin tetrachloride pentahydrate, wherein the mass ratio of the tin tetrachloride pentahydrate, the sodium hydroxide and the polyvinyl pyrrolidone is 179:120:50, and the volume ratio of the anhydrous ethanol and the deionized water is 1:1.

[0010] In some embodiments, the concentration of the chloroauric acid solution is 2.284 mg / mL, and the mass ratio of the chloroauric acid solution to tin tetrachloride is 1:3580.

[0011] In some embodiments, the temperature of the hydrothermal reaction is 160-170° C., and the time of the hydrothermal reaction is 24 hours.

[0012] In some embodiments, the solid-liquid separation is centrifugal separation, wherein the rotation speed of the centrifugal separation is 10000-12000r / min, and the centrifugation time is 1-2min; the drying temperature is 60-80°C, and the time is 12h; the calcination temperature is 450-500°C, the time is 3-4h, and the heating rate is 3-5°C / min.

[0013] According to another aspect of the present application, a gas-sensitive material prepared according to the above method is provided, comprising spherical SnO2 and metal Au doped into the SnO2.

[0014] In some embodiments, the doping amount of the metal Au is 1-2 wt %.

[0015] According to another aspect of the present application, there is provided a use of the gas-sensitive material in detecting carbon monoxide, a heart disease exhaled marker.

[0016] According to another aspect of the present application, a gas-sensitive component is provided, including a gas-sensitive material prepared by the method for preparing a gas-sensitive material or the gas-sensitive material.

[0017] According to another aspect of the present application, a method for preparing a gas-sensitive component is provided, comprising: welding an Al2O3 ceramic tube and a heating resistor wire to a base; dissolving the gas-sensitive material in 1 drop of anhydrous ethanol, stirring with a brush until it becomes a paste, to obtain a paste; applying the paste evenly on the surface of the Al2O3 ceramic tube, drying in an oven at 60°C for 2 minutes, repeating the applying and drying operations 3 times, to obtain a gas-sensitive component.

[0018] The technical solutions provided in the embodiments of the present application include at least the following beneficial effects:

[0019] The present application uses metal Au to modify SnO2, which can increase the specific surface area of ​​the gas-sensitive material, thereby improving the sensitivity of the gas-sensitive material in practical applications.

[0020] Furthermore, the present application dopes SnO2 with precious metal Au, which has catalytic activity and can reduce the activation energy of chemical adsorption of the measured gas, promote the reaction between gas molecules and the surface of the gas-sensitive material, thereby further improving the sensitivity of the gas-sensitive material.

[0021] Furthermore, the present application can more accurately select carbon monoxide gas for detection by selecting the precious metal Au to be doped into SnO2 and selecting different doping amounts, thereby further improving the sensitivity and accuracy of the gas-sensitive material. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 A flow chart of a method for preparing a gas-sensitive material in an embodiment of the present application is shown.

[0024] Figure 2 The X-ray diffraction patterns of the gas-sensitive materials in Examples 1-2 of the present application and the comparative example are shown.

[0025] Figure 3 The scanning electron microscope images of the gas-sensitive materials in Examples 1-2 of the present application and the comparative example are shown.

[0026] Figure 4 The graph shows the test results of the temperature sensitivity of the gas-sensitive components prepared by the gas-sensitive materials in Examples 1-2 of the present application and the comparative example.

[0027] Figure 5 The graph shows the test results of the sensitivity of the gas-sensitive components prepared by the gas-sensitive materials in Example 2 of the present application and the comparative example to the carbon monoxide concentration.

[0028] Figure 6 A graph showing the repeatability test results of the gas-sensitive component prepared by the gas-sensitive material in Example 2 of the present application is shown.

[0029] Figure 7 A graph showing the selectivity test results of the gas-sensitive component prepared by the gas-sensitive material in Example 2 of the present application is shown. DETAILED DESCRIPTION

[0030] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described below in conjunction with the accompanying drawings and embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0031] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0032] Embodiment 1:

[0033] Please see attached Figure 1 , a method for preparing a gas-sensitive material, comprising the following steps:

[0034] S100, add 3.58 g of tin tetrachloride pentahydrate, 2.4 g of sodium hydroxide and 1.0 g of polyvinyl pyrrolidone to 20 ml of anhydrous ethanol and 20 ml of deionized water and stir, then add 442 uL of 2.284 mg / mL chloroauric acid and stir for 40 min to obtain a mixed solution;

[0035] S200, subjecting the mixed solution obtained in S100 to a hydrothermal reaction at a temperature of 170° C. for 24 hours, and cooling after the reaction to obtain a hydrothermal product;

[0036] S300, centrifuging and washing the hydrothermal product twice, with a centrifugal speed of 12000 r / min and a centrifugal time of 2 min to obtain a precipitate;

[0037] S400, drying the precipitate in an oven at 60° C. for 12 h, calcining it at 500° C. for 4 h, and cooling it to room temperature to obtain a 1.0 wt% Au / SnO2 gas-sensitive material.

[0038] Example 2

[0039] S100, add 3.58 g of tin tetrachloride pentahydrate, 2.4 g of sodium hydroxide and 1.0 g of polyvinyl pyrrolidone to 20 ml of anhydrous ethanol and 20 ml of deionized water and stir, then add 884 uL of 2.284 mg / mL chloroauric acid and stir for 40 min to obtain a mixed solution;

[0040] S200, subjecting the mixed solution obtained in S100 to a hydrothermal reaction at a temperature of 160° C. for 24 h, and cooling after the reaction to obtain a hydrothermal product;

[0041] S300, centrifuging and washing the hydrothermal product twice, with a centrifugal speed of 12000 r / min and a centrifugal time of 2 min to obtain a precipitate;

[0042] S400, drying the precipitate in an oven at 60° C. for 12 h, calcining it at 500° C. for 4 h, and cooling it to room temperature to obtain a 2.0 wt% Au / SnO2 gas-sensitive material.

[0043] Comparative Example:

[0044] 3.58g of tin tetrachloride pentahydrate SnCl4, 2.4g of sodium hydroxide and 1.0g of polyvinyl pyrrolidone were added into 20ml of anhydrous ethanol and 20ml of deionized water and stirred to form a mixed solution; the mixed solution was subjected to a hydrothermal reaction at a temperature of 160°C for 24h, and after the reaction was completed, the hydrothermal product was obtained by cooling; the hydrothermal product was centrifuged and washed twice at a centrifugal speed of 10000r / min and a centrifugal time of 1min, and a precipitate was obtained after washing the obtained solid; the precipitate was dried in an oven at 60°C overnight, calcined at 450°C for 3h, and after cooling to room temperature, a SnO2 gas-sensitive material was obtained.

[0045] The gas-sensitive materials prepared in the above Examples 1-2 and Comparative Examples were subjected to X-ray diffraction, and the results are shown in Figure 2 , Figure 2 The XRD patterns of SnO2 gas-sensitive material, 1.0wt% Au / SnO2 gas-sensitive material and 2.0wt% Au / SnO2 gas-sensitive material are included. The prepared samples have four main diffraction peaks at diffraction angles of 26.579°, 33.864°, 38.966° and 51.757°, which correspond to the (110), (101), (111) and (211) crystal planes of SnO2 (PDF#98-000-0151). Figure 2 As shown, an obvious peak shift is observed at low angles, which is caused by the incorporation of Au noble metal.

[0046] The gas-sensitive materials prepared in the above-mentioned Examples 1-2 and the comparative example were observed using a scanning electron microscope. The results are shown in Figure 3 ,in, Figure 3 a and 3b are scanning electron microscope photos of SnO2 gas-sensitive materials prepared in comparative example. Figure 3 c and 3d are scanning electron microscope photos of the 1.0wt% Au / SnO2 gas-sensitive material prepared in Example 1. Figure 3 e and 3f are scanning electron microscope photos of the 2.0wt% Au / SnO2 gas-sensitive material prepared in Example 2. Figure 3 As shown, the SnO2 gas-sensitive material prepared in the comparative example is spherical and has many burrs on the surface. After being doped with metal Au, the Au / SnO2 gas-sensitive material maintains a spherical shape with small protrusions on the surface. The specific surface area of ​​the Au / SnO2 gas-sensitive material is increased, which is more conducive to the adsorption of carbon monoxide gas on its surface, thereby improving the sensitivity of the gas-sensitive material in practical applications.

[0047] Example 3: Preparation of gas-sensitive components

[0048] First, the Al2O3 ceramic tube and the heating resistance wire were welded to the base, and then 5 mg of the above-prepared SnO2, 1.0wt% Au / SnO2 and 2.0wt% Au / SnO2 gas-sensitive materials were dissolved in 1 drop of anhydrous ethanol, and stirred with a brush until it became a paste. Finally, the paste was evenly coated on the surface of the Al2O3 ceramic tube and placed in a 60°C oven for 2 minutes. The above operation was repeated 3 times, and after drying, the SnO2 gas-sensitive component, 1.0wt% Au / SnO2 gas-sensitive component and 2.0wt% Au / SnO2 gas-sensitive component were obtained.

[0049] The SnO2 gas-sensitive element, 1.0wt% Au / SnO2 gas-sensitive element and 2.0wt% Au / SnO2 gas-sensitive element prepared in Example 3 were tested for carbon monoxide sensing performance, wherein the gas-sensitive element includes an Au electrode, an Al2O3 ceramic tube, a nickel-chromium heating resistor wire and a bakelite base. A dynamic gas distribution analysis system was used for the test, and the gas flow rate was controlled by a precision gas flow controller (MFC) to make the test results more reliable. The adjustment of the test target gas of different concentrations can be achieved by controlling the flow rate of the target gas and the air. The test chamber is connected to a heating device to change the operating temperature of the gas-sensitive element (160-340°C). The response (S) of the sensor to the target gas is defined as S=Ra / Rg, where Ra and Rg are the sensor resistances in the air and the target gas, respectively. Response time (τ res) and recovery time (τ recov) It is defined as the time required to reach 90% of the total difference in resistance before and after. During the test, the ambient temperature was 25°C-30°C and the relative humidity (RH) was 15%-30%.

[0050] The test results of the carbon monoxide sensing performance of gas sensitive materials are detailed in Figure 4 —7.

[0051] See also Figure 4 , at different temperatures, the gas-sensing detection curves of SnO2 gas-sensing device, 1.0wt% Au / SnO2 gas-sensing device and 2.0wt% Au / SnO2 gas-sensing device for carbon monoxide gas with a concentration of 100ppm. Figure 4 It can be seen that 1.0wt% Au / SnO2 gas-sensitive material and 2.0wt% Au / SnO2 gas-sensitive material have higher response values ​​to carbon monoxide gas. At 220°C, the corresponding response values ​​are 1.84 and 2.35, respectively.

[0052] See also Figure 5The SnO2 gas sensor and 2.0wt% Au / SnO2 gas sensor were tested for their response to carbon monoxide (220°C) at different concentrations (10ppm, 30ppm, 50ppm, 70ppm, 100ppm) to investigate the response performance of the gas sensor to different concentrations of carbon monoxide. Figure 5 It can be seen that the response values ​​of SnO2 gas-sensitive material and 2.0wt% Au / SnO2 gas-sensitive material to carbon monoxide increase with the increase of nitric oxide concentration, and have a good linear relationship.

[0053] See also Figure 6 , the repeatability test of 100ppm carbon monoxide (220℃) was conducted using 2.0wt% Au / SnO2 gas sensing components to examine the repeatability performance of gas sensing materials. Figure 6 It can be seen that 2.0wt% Au / SnO2 gas-sensitive material has good stability to carbon monoxide. Figure 7 At the same time, the selectivity of 2.0wt% Au / SnO2 gas sensor to carbon monoxide (220℃) was tested to investigate the selectivity of gas-sensitive materials to carbon monoxide. Figure 7 It can be seen that the response performance of 2.0wt% Au / SnO2 gas-sensitive material to four different gases of 100ppm NO, 50ppm CH4, 50ppm H2S and 100ppm CO shows that 2.0wt% Au / SnO2 gas-sensitive material has good selectivity for carbon monoxide.

[0054] Through the above specific implementations, those skilled in the art can easily implement the present invention. However, it should be understood that the present invention is not limited to the above specific implementations. On the basis of the disclosed implementations, those skilled in the art can arbitrarily combine different technical features to achieve different technical solutions.

Claims

1. A method for preparing a gas-sensitive material, characterized in that: include: Add tin tetrachloride, sodium hydroxide and polyvinyl pyrrolidone to anhydrous ethanol and deionized water, stir, add chloroauric acid solution, stir and mix to obtain a mixed solution; The mixed solution is subjected to a hydrothermal reaction, and after the hydrothermal reaction, it is cooled to obtain a hydrothermal product; separating the hydrothermal product into solid and liquid, and washing the solid separated from the solid and liquid to obtain a precipitate; The precipitate is dried, calcined, and cooled to room temperature to obtain the Au / SnO2 gas-sensitive material.

2. The method for preparing a gas-sensitive material according to claim 1, characterized in that: The tin tetrachloride is tin tetrachloride pentahydrate, wherein the mass ratio of the tin tetrachloride pentahydrate, the sodium hydroxide and the polyvinyl pyrrolidone is 179:120:50, and the volume ratio of the anhydrous ethanol and the deionized water is 1:

1.

3. The method for preparing a gas-sensitive material according to claim 1, characterized in that: The concentration of the chloroauric acid solution is 2.284 mg / mL, and the mass ratio of the chloroauric acid solution to tin tetrachloride is 1:3580.

4. The method for preparing a gas-sensitive material according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 160-170° C., and the time of the hydrothermal reaction is 24 hours.

5. The method for preparing a gas-sensitive material according to claim 1, characterized in that: The solid-liquid separation is centrifugal separation, wherein the rotation speed of the centrifugal separation is 10000-12000r / min, and the centrifugal time is 1-2min; the drying temperature is 60-80°C, and the time is 12h; the calcination temperature is 450-500°C, and the time is 3-4h, and the heating rate is 3-5°C / min.

6. The gas-sensitive material obtained by the method according to claim 1, characterized in that: The invention comprises spherical SnO2 and metal Au doped into the SnO2.

7. The gas-sensitive material according to claim 6, characterized in that: The doping amount of the metal Au is 1-2 wt %.

8. Use of the gas-sensitive material according to claim 6 in detecting carbon monoxide, a marker of heart disease.

9. A gas sensing component, characterized in that: The invention comprises a gas-sensitive material prepared by the method for preparing a gas-sensitive material according to any one of claims 1 to 5 or a gas-sensitive material according to any one of claims 6 to 7.

10. The method for preparing the gas sensing element according to claim 9, characterized in that: include: Welding the Al2O3 ceramic tube and the heating resistance wire to the base; Dissolve the gas-sensitive material in 1 drop of anhydrous ethanol, and stir with a brush until it becomes a paste to obtain a paste; The paste was evenly coated on the surface of the Al2O3 ceramic tube, and dried in an oven at 60°C for 2 minutes. The coating and drying operations were repeated 3 times to obtain a gas sensing component.

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