A carbonyl fluoride high-response gas-sensitive material, a preparation method and application thereof, and a sensor

Abstract

The application belongs to the technical field of gas detection, and particularly relates to a carbonyl fluoride high-response gas sensitive material, a preparation method and application thereof, and a sensor. The carbonyl fluoride high-response gas sensitive material provided in the application is contacted with carbonyl fluoride (COF2) gas, and electrons are transferred from Au-doped SnO2 microparticles to carbonyl fluoride gas molecules, which is an exothermic reaction. The Au-doped SnO2 microparticles and the carbonyl fluoride gas can be strongly adsorbed, the resistance of the Au-doped SnO2 microparticles is increased, and the change of the resistance and the concentration of the carbonyl fluoride gas are in a linear relationship, so that the technical problem that there is a lack of a carbonyl fluoride gas sensitive material for detection in the prior art is solved.

Description

Technical Field

[0001] This application belongs to the field of gas detection technology, and particularly relates to a highly responsive carbonyl fluoride gas-sensitive material, its preparation method and application, and a sensor. Background Technology

[0002] Perfluoroisobutyronitrile (C4F7N) has begun to be used as a substitute gas for sulfur hexafluoride (SF6) in the field of electrical equipment insulation due to its good insulation properties and environmental friendliness.

[0003] In practical applications, due to the presence of trace amounts of water and oxygen in electrical equipment, and the potential for internal discharge or overheating faults, perfluoroisobutyronitrile (PFONI) decomposes to varying degrees, producing decomposition gases such as carbonyl fluoride (COF2). The decomposition of PFONI significantly reduces the insulating properties of these gases, leading to equipment malfunctions and even threatening the stable operation of the power grid. Furthermore, COF2 gas is biotoxic and may endanger the safety of on-site personnel; therefore, it is necessary to develop suitable sensors to monitor the presence of these gases.

[0004] In resistive gas sensors, the gas-sensitive material changes its resistance after adsorbing a certain gas, thus enabling the detection of that gas. Resistive gas sensors offer advantages such as long lifespan, low cost, fast detection speed, small size, and simple measurement system, making them a commonly used method for detecting the decomposition components of perfluoroisobutyronitrile (PFONI). However, current resistive gas sensors are typically designed for detecting PFONI gas, and research on sensors for detecting fluorocarbonyl fluoride (FCF), a component of PFONI, is limited, resulting in a lack of gas-sensitive materials suitable for detecting FCF. Summary of the Invention

[0005] In view of this, this application provides a highly responsive carbonyl fluoride gas-sensitive material, its preparation method, applications, and sensors to solve the technical problem of the lack of existing technologies for detecting carbonyl fluoride gas-sensitive materials.

[0006] The first aspect of this application provides a highly responsive gas-sensitive material of fluorinated carbonyl fluoride, comprising Au-doped SnO2 micron-sized particles.

[0007] Preferably, the mass ratio of Au to SnO2 in the Au-doped SnO2 micron particles is 1 to 10:100.

[0008] Preferably, the mass ratio of Au to SnO2 in the Au-doped SnO2 micron particles is 5:100.

[0009] Preferably, the Au-doped SnO2 micron particles have a particle size of 1–20 μm.

[0010] The second aspect of this application provides a method for preparing a highly responsive carbonyl fluoride gas-sensitive material, used to prepare the highly responsive carbonyl fluoride gas-sensitive material described in the first aspect; the preparation method includes the following steps:

[0011] Step A1: Mix the soaking solution of Bengal soybeans, the aqueous solution of tin tetrachloride, and tetrachloroauric acid, then centrifuge and filter to obtain Au-doped SnO2 micron-sized particle precursors;

[0012] Step A2: Calcining the Au-doped SnO2 micron-sized particle precursor to obtain Au-doped SnO2 micron-sized particles.

[0013] Preferably, in step A1, the volume ratio of the Bengal bean soaking solution to the tin tetrachloride aqueous solution is 1:1 to 3;

[0014] The molar ratio of tin atoms in the tin tetrachloride aqueous solution to gold atoms in tetrachloroauric acid is 66:0.5-5.

[0015] Preferably, the molar ratio of tin atoms in the tin tetrachloride aqueous solution to gold atoms in tetrachloroauric acid is 66:2.5.

[0016] Preferably, in step A2, the calcination time is 500-700℃ for 4-8 hours.

[0017] A third aspect of this application provides a gas sensor, comprising the carbonyl fluoride high-response gas-sensitive material and resistance detection device described in the first aspect;

[0018] The highly responsive gas-sensitive material of carbonyl fluoride is coated on the surface of the resistance detection device.

[0019] Preferably, the resistance detection device is an interdigitated electrode.

[0020] The fourth aspect of this application provides the application of the gas-sensitive sensor described in the third aspect in the online monitoring of carbonyl fluoride in electrical equipment.

[0021] Preferably, the application specifically includes:

[0022] Step B1: Input the resistance value of the carbonyl fluoride high-response gas-sensitive material obtained by the resistance detection device into the carbonyl fluoride responsivity calculation formula to obtain the carbonyl fluoride responsivity.

[0023] Step B2: Input the obtained carbonyl fluoride responsivity into the linear relationship between carbonyl fluoride responsivity and carbonyl fluoride concentration to obtain the carbonyl fluoride concentration.

[0024] Preferably, in step B1, the formula for calculating the responsiveness of the carbonyl fluoride is: S = R g -R0 / R0, where R0 represents the resistance value before the introduction of carbonyl fluoride gas, R gThe resistance value is denoted by fluorinated carbon gas, and S is the fluorinated carbon responsivity.

[0025] In step B2, the linear relationship between the carbonyl fluoride responsiveness and the carbonyl fluoride concentration is: y = 1.998x - 6.055, where y is the carbonyl fluoride responsiveness and x is the carbonyl fluoride concentration.

[0026] The carbonyl fluoride highly responsive gas-sensitive material provided in this application exhibits high selectivity and high responsiveness to carbonyl fluoride, a component of perfluoroisobutyronitrile gas decomposition in electrical equipment. After adsorbing carbonyl fluoride, the interdigitated electrode shows an increase in resistance, which is linearly related to the carbonyl fluoride concentration. Therefore, online monitoring of carbonyl fluoride, a component of perfluoroisobutyronitrile gas decomposition in electrical equipment, is realized.

[0027] In summary, this application provides a highly responsive gas-sensitive material of carbonyl fluoride, its preparation method, and its applications and sensors. The highly responsive gas-sensitive material of carbonyl fluoride provided in this application is Au-doped SnO2 micron-sized particles. After the Au-doped SnO2 micron-sized particles come into contact with the F atoms in carbonyl fluoride gas (COF2), both the charge transfer and adsorption energy are negative, indicating that the adsorption range after the Au-doped SnO2 micron-sized particles come into contact with the carbonyl fluoride gas is a stable adsorption model. The adsorption process is an exothermic reaction, during which the carbonyl fluoride gas molecules gain electrons, while the Au-doped SnO2 micron-sized particles... The particles lose electrons on their surface, and compared with pure SnO2 microparticles, the adsorption energy is further reduced after Au doping. This indicates that Au can play a catalytic role, making the adsorption effect stronger and further shortening the response and recovery time of the final sensor. At the same time, after Au-doped SnO2 microparticles adsorb carbonyl fluoride gas, their resistance increases, and the rate of change of resistance value is linearly related to the carbonyl fluoride gas concentration. This shows that the Au-doped SnO2 microparticles provided in this application can be used for the detection of carbonyl fluoride gas concentration, solving the technical problem of lacking gas-sensitive materials for detecting carbonyl fluoride in the prior art. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 Scanning electron microscope image of the carbonyl fluoride highly responsive gas-sensitive material provided in Example 2 of this application (magnification: ×2000);

[0030] Figure 2Scanning electron microscope image of the highly responsive gas-sensitive material of carbonyl fluoride provided in Example 2 of this application (magnification: ×15000);

[0031] Figure 3 This is the elemental distribution diagram of the highly responsive carbonyl fluoride gas-sensitive material provided in Example 2 of this application;

[0032] Figure 4 The gas sensor constructed from the highly responsive carbonyl fluoride gas-sensitive material provided in Example 2 of this application shows the response curves of carbonyl fluoride gas at different concentrations.

[0033] Figure 5 A linear relationship graph of the responsivity of carbonyl fluoride and the concentration of carbonyl fluoride was constructed using a gas-sensitive sensor based on the high-response gas-sensitive material provided in Example 2 of this application.

[0034] Figure 6 The figures are schematic diagrams of the carbonyl fluoride highly responsive gas-sensitive material and ordinary tin dioxide particle structure provided in Embodiment 2 of this application. In the figures, a is a schematic diagram of the ordinary tin dioxide particle structure and b is a schematic diagram of the carbonyl fluoride highly responsive gas-sensitive material structure.

[0035] Figure 7 This is a density of states diagram of the surface of the carbonyl fluoride high-response gas-sensitive material provided in Example 2 of this application before and after adsorption of carbonyl fluoride gas. Detailed Implementation

[0036] This application provides a highly responsive carbonyl fluoride gas-sensitive material, its preparation method, applications, and sensors, to address the lack of technical solutions for detecting carbonyl fluoride gas-sensitive materials in the prior art.

[0037] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0038] Example 1

[0039] Given that current resistive gas sensors are typically designed for the detection of perfluoroisobutyronitrile (PFN) gas and lack the ability to detect the decomposition component of PPFN, fluorocarbonyl fluoride (COF2), Example 1 of this application provides Au-doped SnO2 microparticles as a COF2 gas-sensitive material. When the Au-doped SnO2 microparticles come into contact with F atoms in the COF2 gas, the adsorption process is exothermic, and electrons are transferred from the Au-doped SnO2 microparticles to the COF2 gas molecules. That is, the Au-doped SnO2 microparticles and the COF2 gas molecules... In OF2, the charge transfer and adsorption energy of F atoms after contact are both negative. Au-doped SnO2 microparticles and carbonyl fluoride gas can undergo strong adsorption, and Au doping can further promote the adsorption of carbonyl fluoride gas, increasing the resistance of Au-doped SnO2 microparticles. Experimental results show that the change in resistance is linearly related to the concentration of carbonyl fluoride gas. This indicates that the Au-doped SnO2 microparticles provided in this application can be used to detect the concentration of carbonyl fluoride gas, overcoming the current lack of gas-sensitive materials for detecting carbonyl fluoride gas.

[0040] For the structure of Au-doped SnO2 micron-sized particles, such as Figure 1-2 As shown in the figure, its structure consists of spherical particles with a size of approximately 1 μm, in which Au is uniformly and stably distributed. The elemental distribution of the Au-doped SnO2 micron-sized particles is as follows: Figure 3 As shown, it includes elements such as oxygen, gold, and tin.

[0041] Meanwhile, regarding the amount of gold doping in Au-doped SnO2 microparticles, this application allows for selecting a mass ratio of Au to SnO2 of 1 to 10:100. When the mass ratio of Au to SnO2 is 5:100, Au-doped SnO2 microparticles with high selectivity and high response can be obtained.

[0042] Example 2

[0043] Example 2 of this application provides an embodiment of a method for preparing Au-doped SnO2 micron particles, which can be used to prepare the Au-doped SnO2 micron particles described in Example 1; including the steps of preparing a bean soaking solution, preparing an Au-doped SnO2 micron particle precursor, and preparing the Au-doped SnO2 micron particles.

[0044] The steps for preparing the Bengali bean soaking solution include: soaking 20g of dried Bengali beans (C. arietinum L.) in 50mL of deionized water at room temperature for 6 hours, removing the soaked Bengali beans, and further filtering the solution using a glass fiber filter to remove particulate matter. 10mL of the filtered Bengali bean soaking solution is then taken out for use.

[0045] The steps for preparing Au-doped SnO2 micron-sized particle precursors include: adding 10 mL of an aqueous SnCl4 solution (0.01 M) to 10 mL of a pea soaking solution and diluting to 50 mL; then adding approximately 0.0038 mol of HAuCl4 to the resulting solution to obtain an Au doping ratio of 5 wt% (Au:particulate SnO2 mass ratio of 5:100). After centrifuging the resulting solution, the product is collected and repeatedly filtered and washed to obtain Au-doped SnO2 micron-sized particle precursor powder.

[0046] The steps for preparing Au-doped SnO2 micron particles include: calcining the obtained Au-doped SnO2 micron particle precursor powder at 600℃ for 6 hours to finally obtain dry Au-doped granular SnO2 material.

[0047] Experimental Example 1

[0048] Example 1 of this experiment tests the performance of Au-doped SnO2 micron particles described in Example 2 as a carbonyl fluoride gas-sensitive material.

[0049] The performance testing process included: placing the Au-doped SnO2 micron-sized particle material prepared in Example 2 on the interdigitated electrode of a resistance detection device at room temperature to construct a gas sensor. After passing through a background gas of perfluoroisobutyronitrile (C4F7N) for 30 min, carbonyl fluoride (COF2) gas with concentrations of 10 ppm, 20 ppm, 30 ppm, 40 ppm and 50 ppm was passed through, with each passage lasting 75 s. After passing through carbonyl fluoride (COF2) gas at different concentrations, perfluoroisobutyronitrile (C4F7N) gas was passed through again for 175 s to recover.

[0050] Test results are as follows Figure 4 As shown, from Figure 4 It can be seen that the response sensitivity of the gas sensor increases significantly with the increase of COF2 gas concentration; the response sensitivity is calculated using the formula: S = R g -R0 / R0, where R0 represents the air resistance before the introduction of carbonyl fluoride gas, which is 90kΩ at room temperature, R g The resistance value is denoted by S after the introduction of carbonyl fluoride gas, and S is the response sensitivity of carbonyl fluoride. The calculated response sensitivities of the gas sensor to carbonyl fluoride (COF2) gas at 10 ppm, 20 ppm, 30 ppm, 40 ppm and 50 ppm at room temperature are 16.7%, 31.2%, 51.7%, 74% and 95.4%, respectively.

[0051] Simultaneously, a linear relationship graph between response sensitivity and COF2 gas concentration was established, such as... Figure 5As shown, the fitted linear relationship is y = 1.998x - 6.055, where y is the responsiveness of fluorinated carbon and x is the concentration of fluorinated carbon; R 2 =0.9951, and still has a good response to 10 ppm of carbonyl fluoride (COF2) gas, which indicates that the Au-doped SnO2 micron particles provided in this application are a high-response gas-sensitive material of carbonyl fluoride, which can meet the requirements of the carbonyl fluoride (COF2) gas sensor.

[0052] Furthermore, to investigate the mechanism of Au-doped SnO2 microparticles adsorbing carbonyl fluoride (COF2) gas, this application uses the DFT method to simulate and design a gas-sensitive material for detecting carbonyl fluoride (COF2) gas. The simulation calculation uses the Dmol3 module in Material Studio software.

[0053] First, structural models of granular SnO2 materials and Au-doped SnO2 micron-sized particles were established, and then structural optimization was performed to obtain the optimal structure. A schematic diagram of the structure is shown below. Figure 6 As shown; the above calculations use the DFT-D algorithm to correct for the van der Waals forces present on the surface, and employ the generalized gradient approximation (GGA) method and the Perdew-Burke-Ernzehof (PBE) functional to handle the exchange correlation between electrons; the convergence criterion for structural optimization is set as follows: the geometric energy difference is less than 1.0 × 10⁻⁶. -5 Ha, the force on each atom is less than The maximum displacement distance of each atom is less than

[0054] Then, an adsorption model was established by bringing F atoms of carbonyl fluoride (COF2) gas close to the surface of SnO2 crystal in the structural model, and the adsorption energy and charge transfer amount were calculated.

[0055] The adsorption energy is calculated using the formula: E ad =E Au-SnO2 + gas -E Au-SnO2 -E gas In the calculation formula, E Au-SnO2 + gas E represents the energy of the system after gas adsorption. Au-SnO2 For the energy of the Au-SnO2 system before adsorption, E gas E is the energy of a gas molecule. adThe adsorption energy is the energy change of the system after the adsorption of gas molecules. When the adsorption energy is negative, it indicates that the adsorption process is exothermic and the adsorption is stable. If the adsorption energy is positive, the adsorption is unstable. That is, the larger the negative value, the stronger the adsorption. When undoped Au-atom particulate SnO2 material adsorbs, the adsorption energy is -1.01 eV, while the adsorption energy calculated by the Au-doped SnO2 micron particle adsorption model is -1.71 eV. This indicates that Au plays a catalytic role, making the adsorption of carbonyl fluoride by the gas-sensitive material more effective, which is beneficial to improving the response and recovery time of the sensor.

[0056] The formula for calculating the charge transfer is: ΔQ = Q1 - Q2; where Q1 is the charge of the gas molecules after adsorption, Q2 is the charge of the gas molecules before adsorption, and ΔQ is the charge transfer amount of the system. A positive charge transfer result indicates that gas molecules lose electrons and the sensing material surface gains electrons during the entire adsorption process; a negative result indicates that gas molecules gain electrons and the sensing material surface loses electrons during the entire adsorption process. The results show a stable adsorption structure on the surface of Au-doped SnO2 micron-sized particles, with a calculated charge transfer amount of -0.18e. Furthermore, to analyze the electron gain and loss behavior during the adsorption process on the surface of Au-doped SnO2 micron-sized particles, density of states (DOS) diagrams before and after adsorption were plotted, as shown below. Figure 7 As shown, comparing the density of states diagrams before and after adsorption, it can be found that the density of states shifts to the left after adsorption (red curve); this indicates that the Au-doped SnO2 micron particles provided in this application can be used as a gas-sensitive material for carbonyl fluoride gas to monitor the carbonyl fluoride component of perfluoroisobutyronitrile gas in electrical equipment online.

[0057] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. The application of a gas-sensitive sensor in online monitoring of carbonyl fluoride in electrical equipment, characterized in that; The gas sensor includes a highly responsive carbonyl fluoride gas-sensitive material and a resistance detection device. The highly responsive gas-sensitive material of carbonyl fluoride is coated on the surface of the resistance detection device; The highly responsive gas-sensitive material of the carbonyl fluoride is Au-doped SnO2 micron-sized particles.

2. The application of the gas-sensitive sensor according to claim 1 in online monitoring of carbonyl fluoride in electrical equipment, characterized in that, The mass ratio of Au to SnO2 in the Au-doped SnO2 micron particles is 1~10:

100.

3. The application of the gas-sensitive sensor according to claim 1 in online monitoring of carbonyl fluoride in electrical equipment, characterized in that, The Au-doped SnO2 micron particles have a particle size of 1~20μm.

4. The application of the gas-sensitive sensor according to claim 1 in online monitoring of carbonyl fluoride in electrical equipment, characterized in that, The preparation method of the carbonyl fluoride highly responsive gas-sensitive material includes the following steps: Step A1: Mix the soaking solution of Bengal soybeans, the aqueous solution of tin tetrachloride, and tetrachloroauric acid, stir and centrifuge to obtain Au-doped SnO2 micron-sized particle precursors; Step A2: Calcining the Au-doped SnO2 micron-sized particle precursor to obtain Au-doped SnO2 micron-sized particles.

5. The application of the gas-sensitive sensor according to claim 4 in online monitoring of carbonyl fluoride in electrical equipment, characterized in that, In step A1, the volume ratio of the Bengal bean soaking solution to the tin tetrachloride aqueous solution is 1:1~3; The molar ratio of tin atoms in the tin tetrachloride aqueous solution to gold atoms in tetrachloroauric acid is 66:0.5~5; In step A2, the calcination time is 500~700℃ for 4~8 hours.

6. The application of the gas-sensitive sensor according to claim 1 in online monitoring of carbonyl fluoride in electrical equipment, characterized in that, The resistance detection device is an interdigitated electrode.

7. The application of the gas sensor according to claim 1 in online monitoring of carbonyl fluoride in electrical equipment, Its features are, The specific applications include: Step B1: Input the resistance value of the carbonyl fluoride high-response gas-sensitive material obtained by the resistance detection device into... The formula for calculating the responsivity of carbonyl fluoride is used to obtain the responsivity of carbonyl fluoride. Step B2: Input the obtained carbonyl fluoride responsivity into the linearity of carbonyl fluoride responsivity and carbonyl fluoride concentration. The formula yields the concentration of carbonyl fluoride.

8. The application of the gas-sensitive sensor according to claim 7 in online monitoring of carbonyl fluoride in electrical equipment, characterized in that, In step B1, the formula for calculating the responsiveness of the carbonyl fluoride is: S=(R g -R 0 ） / R 0 ， In the formula, R 0 This indicates the resistance value before the introduction of carbonyl fluoride gas. R g The resistance value after passing carbonyl fluoride gas is introduced. S The responsiveness of carbonyl fluoride; In step B2, the linear relationship between the carbonyl fluoride responsivity and the carbonyl fluoride concentration is as follows: y =1.998 x -6.055, where, y For carbonyl fluoride responsiveness, x This represents the concentration of carbonyl fluoride.

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