A sensor for detecting decomposition components of local faults in C4F7N and its fabrication method.

Abstract

The application provides a sensor for C4F7N local fault decomposition component detection and a preparation method thereof, and belongs to the technical field of gas sensing. The sensor comprises a gas-sensitive material, a screening layer material and an interdigital electrode, the gas-sensitive material is covered on the surface of the interdigital electrode, and the screening layer material is covered on the surface of the gas-sensitive material. In the application, SnO2, Pd-SnO2 and MoS2-SnO2 are used as the gas-sensitive material, the gas-sensitive material is covered on the surface of the interdigital electrode in a drop-coating mode, then the screening layer material Co3(HITP)2 is covered on the surface of the gas-sensitive material in a screen printing mode, thereby forming a double-layer sensor structure. The double-layer structure sensor can detect the decomposition components C3F6, CO and CHF3 of C4F7N under the strong interference of the C4F7N background gas, the three gas-sensitive materials have certain response selectivity for the three gases, and the detection lower limits are 0.195 ppm, 3.12 ppm and 3.66 ppm respectively; and the double-layer structure sensor array has certain qualitative and quantitative identification ability for the mixed gas.

Description

Technical Field

[0001] This invention relates to the field of gas sensing technology, specifically to a sensor for detecting the decomposition components of local faults in C4F7N and its preparation method. Background Technology

[0002] SF6 is a commonly used insulating gas in the power industry, possessing excellent insulation and arc-extinguishing properties. However, SF6 is also a gas with a strong greenhouse effect, and its use is explicitly restricted by clauses in the Kyoto Protocol and the Paris Agreement. To reduce the power system's dependence on SF6, industry experts and scholars have begun to search for new environmentally friendly gases as insulating media in power systems. Among them, C4F7N, as a new type of environmentally friendly gas, has an insulation performance 2.2 times that of SF6, while its potential greenhouse effect is only 1 / 11 of that of SF6, demonstrating extremely high application potential. In the field, as gas-insulated equipment operates, local defects such as free metal particles and poor conductor contact inevitably appear inside. These defects will lead to partial discharge and local overheating faults. Under the influence of these faults, C4F7N will decompose and generate stable characteristic gaseous byproducts. By detecting C3F6, CO, and CHF3 in these characteristic gaseous byproducts, internal faults can be detected in a timely manner, and corresponding operation and maintenance measures can be taken. However, due to its strong electron affinity and the active functional group cyano (-CN), C4F7N exhibits strong interference with the detection of its decomposition components. Therefore, in the early stages of the application of C4F7N-insulated equipment, there is an urgent need to develop a gas sensor that is easy to prepare, low in cost, can operate at room temperature, and has high sensitivity and selectivity for fault decomposition components to address potential internal latent faults that may occur during equipment operation. Summary of the Invention

[0003] To address the shortcomings of the existing technologies, this invention provides a sensor and its preparation method for detecting local fault decomposition components of environmentally friendly insulating gas C4F7N. This sensor is used for real-time monitoring of C4F7N fault decomposition components, which can promptly detect internal equipment faults and facilitate timely implementation of corresponding maintenance measures.

[0004] To achieve the above objectives, the specific technical solution of the present invention is as follows:

[0005] A sensor for detecting decomposition components of local faults in C4F7N includes a gas-sensitive material, a screening layer material, and interdigitated electrodes. The gas-sensitive material covers the surface of the interdigitated electrodes, and the screening layer material covers the surface of the gas-sensitive material. The screening layer material includes a two-dimensional metal-organic framework material, Co3(HITP)2.

[0006] Furthermore, the gas-sensitive material is applied to the surface of the interdigitated electrode by drop coating, and the screening layer material is applied to the surface of the gas-sensitive material by screen printing.

[0007] Furthermore, the mass ratio of the gas-sensitive material to the screening layer material is 20:1.

[0008] Furthermore, the preparation steps of Co3(HITP)2 are as follows:

[0009] S1. Mix Co(NO3)2·6H2O and DMF, heat to 65 °C, and then add an aqueous solution of 2,3,6,7,10,11-hexaaminotriphenylhexahydrochloride (HATP·6HCl) to obtain a mixture;

[0010] S2. Add 2 mol / L NaOAc aqueous solution to the mixture and react at 65 °C for 2 h. Filter the obtained black powder, centrifuge and wash it several times, and dry it to obtain Co3(HITP)2 particles.

[0011] Furthermore, the molar ratio of Co(NO3)2·6H2O to 2,3,6,7,10,11-hexaaminotriphenylhexahydrochloride is 1:0.25.

[0012] Furthermore, the gas-sensitive material includes SnO2 (tin dioxide), Pd-SnO2 (palladium-doped tin dioxide), and MoS2-SnO2 (tin dioxide-doped molybdenum disulfide).

[0013] Furthermore, the SnO2 is obtained by electrospinning and calcining raw materials including tin dichloride.

[0014] Furthermore, the preparation steps of the SnO2 include:

[0015] S1. Mix SnCl2·2H2O, ethanol and N,N-dimethylformamide (DMF) evenly at room temperature, then add polyvinylpyrrolidone (PVP) and mix thoroughly at 60~70 °C to form a viscous colloidal mixture as a precursor solution for electrospinning.

[0016] S2. Nanofibers are obtained by electrospinning the precursor solution.

[0017] S3. Anneal the nanofibers in air at 500 °C for 2 hours to remove PVP and obtain pure SnO2 nanofibers.

[0018] Furthermore, the molecular weight of the polyvinylpyrrolidone is 1,300,000.

[0019] Furthermore, the mass ratio of SnCl2·2H2O to polyvinylpyrrolidone is 1:(4.3~4.5).

[0020] Furthermore, the electrospinning process parameters are as follows: constant voltage of 15 kV, electrode distance of 13 cm, and pumping rate of 0.8 mL / h.

[0021] Furthermore, the Pd-SnO2 is prepared by a hydrothermal method.

[0022] Furthermore, the preparation steps of the Pd-SnO2 include:

[0023] S1. SnCl2·2H2O, C6H5Na3O7·2H2O, PdCl2, ethanol and water are thoroughly mixed at room temperature to obtain a precursor suspension;

[0024] S2. The precursor suspension was reacted at 180 °C for 12 h. After cooling to room temperature, it was filtered, centrifuged, washed, and dried to obtain Pd-SnO2 particles.

[0025] Furthermore, the molar ratio of SnCl2·2H2O, C6H5Na3O7·2H2O, and PdCl2 is 5:10:0.2.

[0026] Furthermore, the MoS2-SnO2 is obtained by growing particulate SnO2 on the surface of MoS2 nanoflowers.

[0027] Furthermore, the preparation steps of the MoS2-SnO2 include:

[0028] S1. Mix Na2MoO4·2H2O, CH3CSNH2 and water at room temperature until homogeneous, then add hexadecyltrimethylammonium bromide (CTAB) and mix until homogeneous to obtain a mixture;

[0029] S2. The mixture was reacted at 180 °C for 24 h, cooled to room temperature, and then centrifuged, washed, and dried to obtain MoS2 nanoflowers.

[0030] S3. MoS2 nanoflowers, SnCl2·2H2O and water were thoroughly mixed and reacted at 180 °C for 12 h. After cooling to room temperature, MoS2-SnO2 particles were obtained by repeated centrifugation, washing and drying.

[0031] Furthermore, the mass ratio of Na2MoO4·2H2O, CH3CSNH2, and hexadecyltrimethylammonium bromide is 1:1:0.3.

[0032] Furthermore, the mass ratio of the MoS2 nanoflowers to SnCl2·2H2O is 4:1.

[0033] The method for preparing the sensor for detecting the decomposition components of local faults in C4F7N includes the following steps:

[0034] (1) Prepare solutions of SnO2, Pd-SnO2 and MoS2-SnO2 respectively, and drop the solutions onto the surface of the interdigitated electrode. After vacuum drying at 65 °C, a gas-sensitive layer is formed.

[0035] (2) The screening layer material solution is screen printed onto the surface of the gas-sensitive layer and then vacuum dried at 65 °C to form a screening layer, thus obtaining a sensor for detecting the decomposition components of C4F7N local faults.

[0036] Furthermore, the concentrations of the SnO2, Pd-SnO2, and MoS2-SnO2 solutions are all 1 mg / 40 μL.

[0037] Furthermore, the concentration of the screening layer material solution is 1 mg / 200 μL.

[0038] The design principle of this invention is as follows: This invention uses SnO2, Pd-SnO2, and MoS2-SnO2 as gas-sensitive materials. These gas-sensitive materials are coated onto the surface of the interdigitated electrode via drop-coating. Then, a screening layer material, Co3(HITP)2, is screen-printed onto the surface of the gas-sensitive materials, thereby forming a double-layer sensing structure. When the Co3(HITP)2 screening layer in this invention comes into contact with C4F7N gas molecules, the Co in Co3(HITP)2... 2+ Ions interact strongly with the -CN groups in C4F7N molecules, causing C4F7N molecules in the background gas to be bound to the surface of the Co3(HITP)2 screening layer. The micropores in Co3(HITP)2 provide diffusion channels for the faulty decomposition component gas molecules, allowing the gas-sensitive layer below the screening layer to contact the target gas molecules and undergo charge transfer, resulting in a selective response. SnO2, Pd-SnO2, and MoS2-SnO2 in the gas-sensitive layer can selectively respond to the components C3F6, CO, and CHF3 produced by the decomposition of C4F7N based on their active sites, respectively. This constitutes a sensing array, which, after processing by the KPCA algorithm, enables qualitative and quantitative identification of the mixed gas.

[0039] Compared with the prior art, the advantages of the present invention are:

[0040] (1) The dual-layer gas sensor based on Co3(HITP)2 screening and filtration provided by the present invention is used for real-time monitoring of C4F7N fault decomposition components, which can promptly detect internal faults of equipment and promptly carry out corresponding operation and maintenance measures; in addition, the sensor has a low detection limit, and its detection limits for C3F6, CO and CHF3 are 0.195 ppm, 3.12 ppm and 3.66 ppm, respectively.

[0041] (2) The present invention constructs a double-layer sensor by coating a Co3(HITP)2 screening layer on the surface of different gas-sensitive materials. While retaining the selectivity of the original gas-sensitive materials, it significantly improves the sensor’s ability to suppress interference from high-concentration C4F7N background gas. Attached Figure Description

[0042] Figure 1 The morphology of SnO2 nanofibers provided by this invention is shown under a scanning electron microscope.

[0043] Figure 2 The morphology of Pd-SnO2 particles provided by this invention is shown under a scanning electron microscope.

[0044] Figure 3 The morphology of MoS2-SnO2 particles provided by this invention is shown under a scanning electron microscope.

[0045] Figure 4 The image shows the morphology of the Co3(HITP)2 particles provided by this invention under a scanning electron microscope.

[0046] Figure 5 This is a comparison diagram of the response of the sensor pair prepared in Example 1 and Comparative Example 1 to C4F7N.

[0047] Figure 6 The image shows the effect of KPCA processing on the sensing data of a single gas and a gas mixture prepared by the sensor in Example 1. Detailed Implementation

[0048] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] This invention provides a sensor for detecting decomposition components of local faults in C4F7N, comprising a gas-sensitive material, a screening layer material, and interdigitated electrodes. The gas-sensitive material covers the surface of the interdigitated electrodes, and the screening layer material covers the surface of the gas-sensitive material. The screening layer material comprises a two-dimensional metal-organic framework material Co3(HITP)2.

[0050] In the following specific embodiments, the gas-sensitive material is coated onto the surface of the interdigitated electrode by drop coating, and the screening layer material is coated onto the surface of the gas-sensitive material by screen printing.

[0051] In the following specific embodiments, the mass ratio of the gas-sensitive material to the screening layer material is 20:1.

[0052] In the following specific embodiments, the gas-sensitive material includes SnO2 (tin dioxide), Pd-SnO2 (palladium-doped tin dioxide), and MoS2-SnO2 (tin dioxide-doped molybdenum disulfide).

[0053] In the following specific embodiments, the SnO2 is obtained by electrospinning and calcining of raw materials including tin dichloride; the Pd-SnO2 particles are prepared by hydrothermal method; and the MoS2-SnO2 is obtained by growing granular SnO2 on the surface of MoS2 nanoflowers.

[0054] The specific steps for preparing SnO2 are as follows:

[0055] S1. Add 0.328 g of SnCl2·2H2O, 5 mL of ethanol, and 5 mL of DMF to a reagent bottle and stir for 10 min at room temperature. Then add 1.445 g of polyvinylpyrrolidone (PVP, molecular weight = 1,300,000) and stir at 65 °C for 8 h to form a viscous colloidal mixture as a precursor solution for electrospinning.

[0056] S2. The precursor solution was loaded into a plastic syringe and electrospun at a constant voltage of 15 kV, an electrode distance of 13 cm and a pumping rate of 0.8 mL / h to obtain nanofibers.

[0057] S3. The nanofibers were annealed in a muffle furnace at 500 °C in air for 2 hours to remove PVP, finally obtaining pure SnO2 nanofibers. The morphology of the SnO2 nanofibers under a scanning electron microscope is shown in the figure below. Figure 1 As shown.

[0058] The specific steps for preparing Pd-SnO2 are as follows:

[0059] S1. Add 1.128 g of SnCl2·2H2O, 2.941 g of C6H5Na3O7·2H2O, 0.0369 g of PdCl2, 20 mL of ethanol and 20 mL of deionized water to a beaker and stir thoroughly at room temperature for 1 h to obtain a precursor suspension.

[0060] S2. The precursor suspension was transferred to a 50 mL stainless steel autoclave lined with polytetrafluoroethylene and reacted at 180 °C for 12 h. After cooling to room temperature, the reaction product was filtered out of the solution, followed by multiple centrifugal washings with ethanol and deionized water, and finally freeze-dried to obtain Pd-SnO2 particles. The morphology of the Pd-SnO2 particles under a scanning electron microscope is shown in the figure below. Figure 2 As shown.

[0061] The specific steps for preparing MoS2-SnO2 are as follows:

[0062] S1. Add 1 g of Na2MoO4·2H2O, 1 g of CH3CSNH2 and 50 mL of deionized water to a beaker and stir at room temperature for 10 min. Then add 0.3 g of hexadecyltrimethylammonium bromide (CTAB) to the above solution and continue stirring for 30 min to obtain a mixture.

[0063] S2. The mixture was transferred to a 100 mL stainless steel autoclave lined with polytetrafluoroethylene and reacted at 180 °C for 24 h. The precipitate was separated by centrifugation and purified by washing with ethanol and deionized water multiple times. After freeze-drying for 12 hours, MoS2 nanoflowers were obtained.

[0064] S3, MoS2 nanoflowers and SnCl2·2H2O were mixed in deionized water at a mass ratio of 4:1 and stirred thoroughly for 1 h to obtain a mixture. This mixture was then subjected to a hydrothermal reaction at 180 °C for 12 h. After cooling to room temperature, the product was purified by repeated centrifugation and washing with ethanol and deionized water. MoS2-SnO2 particles were obtained by freeze-drying. The morphology of the MoS2-SnO2 particles under a scanning electron microscope is shown in the image below. Figure 3 As shown.

[0065] In the following specific embodiments, the preparation steps of Co3(HITP)2 are as follows:

[0066] S1. Add 27.1 mg of Co(NO3)2·6H2O and 1.5 mL of N,N-dimethylformamide (DMF) to a beaker and heat to 65°C. Then, dissolve 8 mg of 2,3,6,7,10,11-hexaaminotriphenylhexahydrochloride (HATP·6HCl) in 1.5 mL of deionized water and add it dropwise to the above solution to obtain a mixture.

[0067] S2. Add 2 mL of 2 mol / L NaOAc aqueous solution to the mixture, stir continuously at 65 °C for 2 h, filter the resulting black powder, then wash repeatedly by centrifugation with deionized water and ethanol, and freeze-dry to obtain Co3(HITP)2 particles. The morphology of the Co3(HITP)2 particles under a scanning electron microscope is shown in the figure below. Figure 4 As shown.

[0068] Example 1

[0069] A sensor for detecting components decomposing local faults in C4F7N is fabricated using the following steps:

[0070] S1. Prepare solutions of SnO2, Pd-SnO2 and MoS2-SnO2 as 1 mg / 40 μL respectively. After sonication for 1 h, add 10 μL of each solution to the surface of the interdigitated electrode. After vacuum drying at 65 ℃ for 6 h, a gas-sensitive layer is formed.

[0071] S2. Co3(HITP)2 was prepared into a 1 mg / 200 μL solution. After sonication for 1 h, 2.5 μL was added to the surface of the dry gas-sensitive layer by screen printing. After vacuum drying at 65 ℃ for 6 h, a sensor for detecting the decomposition components of local faults in C4F7N was obtained.

[0072] Comparative Example 1

[0073] A sensor for detecting components decomposing local faults in C4F7N is fabricated using the following steps:

[0074] S1. Three materials, SnO2, Pd-SnO2 and MoS2-SnO2, were prepared into solutions of 1 mg / 40 μL. After sonication for 1 h, 10 μL of each was added dropwise to the surface of the interdigitated electrode. After vacuum drying at 65 ℃ for 6 h, a sensor for detecting the decomposition components of local faults in C4F7N was obtained.

[0075] At room temperature, the sensors prepared in Example 1 and Comparative Example 1 were placed in resistance detection devices. A 6% C4F7N / 94% CO2 mixed gas was first introduced into the device for a period of time until the sensor resistance stabilized. Subsequently, different types and concentrations of fault decomposition component gases (C3F6, CO, CHF3) were introduced into the device, and the change in sensor resistance was observed. When the response approached saturation, the 6% C4F7N / 94% CO2 mixed gas was reintroduced. The test results are as follows: Figure 5 As shown. From Figure 5 It can be seen that the presence of the Co3(HITP)2 screening layer greatly improves the sensor's sensitivity to C3F6, CO, and CHF3. Furthermore, the response data of the sensor prepared in Example 1 to single gases and mixed gases were processed by KPCA and then... Figure 6 The information is given in [the document / source]. Figure 6 It can be seen that the dotted and line regions composed of different types of gases do not overlap, indicating that the sensor has a certain qualitative and quantitative identification capability for single gases and gas mixtures.

[0076] In summary, this invention uses SnO2, Pd-SnO2, and MoS2-SnO2 as gas-sensitive materials. These materials are applied to the surface of interdigitated electrodes via drop-coating, and then a screening layer material, Co3(HITP)2, is screen-printed onto the gas-sensitive material surface, thus forming a dual-layer sensing structure. This dual-layer sensor array can detect the decomposition components C3F6, CO, and CHF3 under strong interference from the C4F7N background gas. The three gas-sensitive materials exhibit specific selectivity for each of the three gases, with detection limits of 0.195 ppm, 3.12 ppm, and 3.66 ppm, respectively. Furthermore, the experimental data processed using the KPCA algorithm forms non-overlapping sample points, indicating that this dual-layer sensor array possesses a certain qualitative and quantitative identification capability for mixed gases.

[0077] The above detailed embodiments describe the implementation of the present invention; however, the present invention is not limited to the specific details described in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A sensor for detecting components of localized faults in C4F7N, characterized in that, The system includes a gas-sensitive material, a screening layer material, and interdigitated electrodes. The gas-sensitive material covers the surface of the interdigitated electrodes and is used to selectively respond to the decomposition components C3F6, CO, and CHF3 of C4F7N molecules. The screening layer material covers the surface of the gas-sensitive material and is used to bind C4F7N molecules, eliminating interference from C4F7N molecules on their decomposition components. The screening layer material includes Co3(HITP)2. The gas-sensitive material includes SnO2, Pd-SnO2, and MoS2-SnO2. The method for preparing the sensor for detecting the decomposition components of local faults in C4F7N includes the following steps: (1) Prepare solutions of SnO2, Pd-SnO2 and MoS2-SnO2 respectively, and drop the solutions onto the surface of the interdigitated electrode. After vacuum drying, a gas-sensitive layer is formed. (2) Co3(HITP)2 solution was screen printed onto the surface of the gas-sensitive layer and then dried under vacuum to obtain a sensor for detecting the decomposition components of local faults in C4F7N.

2. The sensor for detecting decomposition components of local faults in C4F7N according to claim 1, characterized in that, The mass ratio of the gas-sensitive material to the screening layer material is 20:

1.

3. The sensor for detecting decomposition components of local faults in C4F7N according to claim 1, characterized in that, The preparation steps of Co3(HITP)2 are as follows: S1. Mix Co(NO3)2·6H2O and DMF, heat to 65 °C, and then add 2,3,6,7,10,11-hexaaminotriphenylhexahydrochloride solution to obtain a mixture; S2. Add NaOAc solution to the mixture and react at 65 °C for 2 h. After filtration, multiple centrifugation and washing, and drying, Co3(HITP)2 particles are obtained.

4. The sensor for detecting decomposition components of local faults in C4F7N according to claim 3, characterized in that, The molar ratio of Co(NO3)2·6H2O to 2,3,6,7,10,11-hexaaminotriphenylhexahydrochloride is 1:0.

25.

5. The sensor for detecting decomposition components of local faults in C4F7N according to claim 1, characterized in that, The preparation steps of SnO2 include: S1. Mix SnCl2·2H2O, ethanol and DMF evenly, then add polyvinylpyrrolidone and mix thoroughly at 60~70 ℃ to form a viscous colloidal mixture as a precursor solution for electrospinning. S2. Nanofibers are obtained by electrospinning the precursor solution. S3. Anneal the nanofibers at 500 °C to obtain pure SnO2 nanofibers.

6. The sensor for detecting decomposition components of local faults in C4F7N according to claim 1, characterized in that, The preparation steps of the Pd-SnO2 include: S1. Thoroughly mix SnCl2·2H2O, C6H5Na3O7·2H2O, PdCl2, ethanol and water to obtain a precursor suspension; S2. The precursor suspension was reacted at 180 °C for 12 h. After cooling to room temperature, it was filtered, centrifuged, washed, and dried to obtain Pd-SnO2 particles.

7. A sensor for detecting decomposition components of local faults in C4F7N according to claim 6, characterized in that, The molar ratio of SnCl2·2H2O, C6H5Na3O7·2H2O, and PdCl2 is 5:10:0.

2.

8. A sensor for detecting decomposition components of local faults in C4F7N according to claim 1, characterized in that, The preparation steps of MoS2-SnO2 include: S1. Mix Na2MoO4·2H2O, CH3CSNH2 and water evenly, then add hexadecyltrimethylammonium bromide and mix evenly to obtain a mixture; S2. The mixture was reacted at 180 °C for 24 h, cooled to room temperature, and then centrifuged, washed, and dried to obtain MoS2 nanoflowers. S3. MoS2 nanoflowers, SnCl2·2H2O and water were thoroughly mixed and reacted at 180 °C for 12 h. After cooling to room temperature, MoS2-SnO2 particles were obtained by repeated centrifugation, washing and drying.

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