Preparation method of LaBO3 gas sensitive material, gas sensitive sensor and application

Abstract

The invention discloses a preparation method of a LaBO3 gas sensitive material, a gas sensitive sensor and application, and relates to the technical field of gas sensors. The spherical LaBO3 nano-particles are prepared by adopting a sol-gel method and have smaller particle size and larger specific surface area, so that the sensitivity of gas detection is enhanced; the LaBO3 nanoparticles are uniformly and tightly distributed, so that a good electron conduction network can be formed, and the response speed of gas detection is increased; the LaBO3 nano-particles have remarkable response to SO2F2 gas and are a novel gas sensitive material, and a gas sensitive sensor prepared by taking the LaBO3 nano-particles as the gas sensitive material is suitable for effective detection of SO2F2 gas in a complex environment and has huge application potential.

Description

Technical Field

[0001] The present invention relates to the technical field of gas sensors, and in particular to a preparation method of a LaBO3 gas-sensitive material, a gas-sensitive sensor and applications. Background Art

[0002] Sulfur hexafluoride (SF6) is widely used as an insulating gas for high-voltage electrical equipment due to its good insulation properties and arc extinguishing ability. However, during the operation of the equipment, factors such as arc discharge and local overheating may cause SF6 gas to decompose and generate chemically active byproducts such as sulfuryl difluoride (SO2F2); the accumulation of these decomposition products will reduce the insulation performance of electrical equipment and even endanger the stability of the system; therefore, real-time monitoring and detection of SO2F2 is crucial to ensure the safe operation of the power system.

[0003] In the existing technology, sensors for SF6 decomposition products such as SO2F2 often have shortcomings such as insufficient sensitivity and slow response time. In particular, the performance of sensors tends to decrease significantly in high temperature and high humidity environments. Therefore, the development of a sensor material with high sensitivity, fast response speed and adaptability to complex environments has become an urgent technical need. Summary of the invention

[0004] The present invention provides a preparation method of a LaBO3 gas-sensitive material, a gas-sensitive sensor and application thereof, aiming at efficiently detecting SO2F2.

[0005] The LaBO3 gas-sensitive material provided by the present invention is prepared by a sol-gel method. The preparation method of the LaBO3 gas-sensitive material comprises the following steps:

[0006] S1, adding boric acid and lanthanum nitrate into distilled water, stirring thoroughly to dissolve, and then adding citric acid as a complexing agent to prepare a mixed solution;

[0007] S2, stirring the mixed solution at 60° C. for 2 h to obtain a sol;

[0008] S3, drying the sol to obtain a dried gel;

[0009] S4, calcining the gel at 500° C. for 3 h to obtain LaBO 3 nanoparticles.

[0010] Optionally, the concentration of boric acid in the mixed solution is 0.1M, and the concentration of lanthanum nitrate is 0.1M.

[0011] Optionally, in step S3, the condition for drying the sol is constant temperature drying at 150°C.

[0012] Optionally, in step S4, the particle size of the LaBO3 nanoparticles is 20-150 nm.

[0013] The gas sensor provided by the present invention comprises a substrate, interdigital electrodes arranged on the substrate, and a gas sensitive layer arranged on the interdigital electrodes;

[0014] The gas-sensitive layer comprises LaBO3 nanoparticles prepared by the above-mentioned method for preparing the LaBO3 gas-sensitive material.

[0015] Optionally, the gas sensor is prepared by the following steps:

[0016] S5, preparing interdigital electrodes on the substrate;

[0017] S6, dispersing the LaBO3 nanoparticles in ethanol to obtain a LaBO3 nanoparticle dispersion;

[0018] S7, using a spin coating method to evenly coat the LaBO3 nanoparticle dispersion on the surface of the interdigital electrode;

[0019] S8, drying the interdigital electrode coated with the LaBO3 nanoparticle dispersion at 80°C, and then sintering at 400°C for 1h to obtain the gas sensing layer;

[0020] Optionally, the step S5 specifically includes the following steps:

[0021] S51, depositing a silver thin film on the surface of the substrate by electron beam evaporation;

[0022] S52, patterning the silver film by photolithography to obtain the interdigitated electrodes, wherein the electrode spacing of the interdigitated electrodes can be 20 μm;

[0023] S53, performing thermal annealing on the interdigital electrodes, wherein the thermal annealing temperature is 150° C. and the thermal annealing time is 1 hour.

[0024] Optionally, in step S7, the spin coating speed is 2000 rpm and the spin coating time is 30 s.

[0025] Optionally, after step S8, the following steps are also included:

[0026] S9, encapsulating the substrate and the interdigital electrodes with ultraviolet curing adhesive; the encapsulated gas sensor is provided with an opening, and the gas-sensitive layer is connected to the external environment through the opening.

[0027] The present invention also proposes the use of the above-mentioned LaBO3 gas-sensitive material or gas-sensitive sensor in detecting SO2F2 gas.

[0028] The present invention has the following beneficial effects:

[0029] The present invention adopts a sol-gel method to prepare spherical LaBO3 nanoparticles, which have a small particle size and a large specific surface area, thereby enhancing the sensitivity of gas detection; the LaBO3 nanoparticles are evenly and tightly distributed, and a good electron conduction network can be formed, thereby improving the response speed of gas detection; the LaBO3 nanoparticles prepared by the present invention have a significant response to SO2F2 gas, thus filling the gap in the research related to LaBO3 as a SO2F2 gas-sensitive material, and LaBO3 has good thermal stability and chemical stability, thereby being suitable for the effective detection of SO2F2 gas in complex environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] 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 or the description of the prior art 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 labor.

[0031] Figure 1 This is a microscopic morphology structure diagram of LaBO3 nanoparticles prepared by the present invention;

[0032] Figure 2 is a histogram of the response characteristics of the gas sensor of the present invention to different gases;

[0033] Figure 3 The graph is a response curve of the gas sensor of the present invention to SO2F2 gas of different concentrations. DETAILED DESCRIPTION

[0034] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] After intensive research, the inventors of this application discovered that LaBO3 nanoparticles prepared by a specific method have a significant response to SO2F2 gas and can be used to efficiently detect SO2F2 gas. They are suitable for real-time monitoring and detection of SO2F2, the decomposition product of SF6 gas, in high-voltage electrical equipment, and are crucial to ensuring the safe operation of the power system.

[0036] Preparation method of LaBO3 gas-sensitive material

[0037] The first aspect of the present application provides a method for preparing a LaBO3 gas-sensitive material, wherein the LaBO3 gas-sensitive material is prepared by a sol-gel method, and specifically comprises the following steps:

[0038] S1, adding boric acid (H3BO3) and lanthanum nitrate (La(NO3)3) into distilled water, stirring thoroughly to dissolve, and then adding citric acid as a complexing agent to prepare a mixed solution.

[0039] In this step, the carboxyl and hydroxyl groups in the citric acid molecules can provide lone pairs of electrons to form stable complexes with lanthanum ions in the mixed solution, which can enhance the dispersion and activity of LaBO3 nanoparticles prepared by the sol-gel method.

[0040] S2, fully stirring the mixed solution at 60° C. to obtain a sol.

[0041] In this step, due to the complexation reaction occurring in the mixed solution, the mixed solution forms a sol with uniform composition after being fully stirred at 60°C.

[0042] S3, drying the sol to obtain a dried gel.

[0043] In this step, the sol is dried to remove excess solvent and reaction by-products (eg, decomposition products of nitric acid, etc.).

[0044] S4, calcining the dried gel at 500°C to obtain LaBO3 nanoparticles.

[0045] Example

[0046] 0.1M boric acid (H3BO3) and 0.1M lanthanum nitrate (La(NO3)3) were added into distilled water, and after being fully stirred and dissolved, citric acid was added as a complexing agent to prepare a mixed solution; the molar ratio of borate ions to lanthanum ions in the mixed solution was 1:1.

[0047] The mixed solution was fully stirred at 60° C. for 2 h to obtain a sol.

[0048] The sol was dried at a constant temperature of 150° C. to obtain a dried gel.

[0049] The dried gel was calcined at 500 °C for 3 h to obtain LaBO3 nanoparticles.

[0050] like Figure 1 As shown, the LaBO3 prepared in this embodiment is a nanoparticle with a highly crystalline structure; the LaBO3 nanoparticles are in the form of nanospheres, the particle size of the spherical nanoparticles is 20-150nm, the nanoparticles are distributed relatively closely, and there are tiny gaps between the particles.

[0051] Since LaBO3 has certain semiconductor properties, its conductivity will change with the adsorption and reaction of gas molecules; when LaBO3 forms a nanostructure, the surface of the nanostructure is rich in defects (such as lattice defects, oxygen vacancy defects at grain boundaries, etc.) and other active sites (such as metal ion active sites, and the pore structure can increase these active sites). These active sites can adsorb SO2F2 molecules and react, affecting the conductivity of LaBO3 nanoparticles; LaBO3 nanoparticles are prepared into the gas-sensitive layer of the gas sensor, and the concentration change of SO2F2 gas can be accurately reflected by measuring the conductivity change of the gas-sensitive layer.

[0052] The LaBO3 nanoparticles prepared in this embodiment have a spherical structure, which can increase the contact area between the material and the gas and enhance the sensitivity of gas detection; the particle size of the LaBO3 nanoparticles is 20-150nm, and the smaller particle size allows a large number of pores to be formed between the particles, which is beneficial to the diffusion, adsorption and reaction of SO2F2 molecules, further enhancing the sensitivity of gas detection; the LaBO3 nanoparticles are distributed relatively densely, and the densely distributed nanoparticles can form a good electron conduction network, making the transmission of electrical signals more stable. When the gas is adsorbed on the surface of the particles and causes a change in conductivity, the electrical signal can be transmitted rapidly, thereby improving the response speed of gas detection.

[0053] Gas Sensor

[0054] Based on the LaBO3 nanoparticles obtained in the above-mentioned preparation method embodiment, the second aspect of the present application provides a gas sensor; the gas sensor includes a substrate, interdigitated electrodes arranged on the substrate, and a gas sensitive layer arranged on the interdigitated electrodes; the gas sensitive layer contains the LaBO3 nanoparticles prepared in the above-mentioned preparation method embodiment.

[0055] The gas sensor is prepared by the following steps:

[0056] S5, preparing interdigitated electrodes on the substrate.

[0057] Specifically, the substrate material may be selected from insulating ceramics such as one or more of aluminum oxide, aluminum nitride, silicon nitride, silicon carbide, zirconium oxide, and boron nitride ceramics to ensure the stability and insulation of the gas sensor in harsh environments.

[0058] The preparation of the interdigital electrodes on the substrate specifically includes the following steps S51-S53:

[0059] S51, depositing a silver thin film on the surface of the substrate by electron beam evaporation.

[0060] Specifically, the silver film has high conductivity, which helps to improve the electrochemical response of the interdigital electrode to gas adsorption, thereby improving the response speed of the gas sensor.

[0061] It should be noted that this step may also use other conductive materials with good conductivity and environmental stability instead of the silver film, such as gold, platinum, conductive carbon layer, etc. Those skilled in the art may prepare these conductive materials using known methods according to actual needs. Accordingly, the subsequent processing steps of the silver film may also be adjusted according to the actual conductive material selected.

[0062] S52, patterning the silver film by photolithography to obtain interdigitated electrodes.

[0063] Specifically, after the pattern of the interdigitated electrodes is defined by photolithography technology, the silver film is photolithographically processed to obtain the target interdigitated electrodes. The photolithography technology can prepare interdigitated electrodes with high precision and high resolution.

[0064] S53, performing thermal annealing on the interdigital electrodes, with the thermal annealing temperature being 150°C.

[0065] Specifically, thermal annealing of the silver thin film can enhance the adhesion and durability of the silver thin film on the substrate.

[0066] After the interdigital electrodes are prepared on the substrate, a gas-sensitive layer is prepared on the interdigital electrodes by spin coating, which specifically includes the following steps:

[0067] S6, dispersing the LaBO3 nanoparticles prepared in the above preparation method example in ethanol to obtain a LaBO3 nanoparticle dispersion.

[0068] Specifically, ethanol has moderate volatility and can be well mixed with LaBO3 nanoparticles, which not only improves the preparation efficiency but also ensures the uniformity of the LaBO3 nanoparticle dispersion; and ethanol is compatible with LaBO3 nanoparticles, insulating ceramic substrates, metal interdigital electrodes, etc., and will not cause corrosion or chemical reactions to these materials.

[0069] S7, using a spin coating method to evenly coat the LaBO3 nanoparticle dispersion on the surface of the interdigital electrode.

[0070] Specifically, the gas-sensitive layer prepared by the spin coating method has good thickness uniformity and high surface flatness, which helps to improve the consistency and stability of the gas sensor. The spin coating method has low equipment requirements and a short preparation process, and is suitable for application in laboratories and industrial production, thereby improving production efficiency.

[0071] S8, drying the interdigital electrode coated with the LaBO3 nanoparticle dispersion at 80°C, and then sintering at 400°C to obtain the target gas sensing layer.

[0072] Specifically, sintering the gas-sensitive layer spin-coated on the surface of the interdigital electrode at 400° C. can further enhance the compactness and stability of the LaBO3 nanoparticles in the gas-sensitive layer and improve the gas response capability of the gas-sensitive layer.

[0073] S9, after the gas-sensitive layer is prepared, the substrate and the interdigital electrodes prepared with the gas-sensitive layer are packaged.

[0074] Specifically, when the gas sensor is used in an actual working environment, the gas sensor usually includes components such as a housing, electrode leads, pins and interfaces in addition to a substrate, interdigitated electrodes and a gas sensitive layer provided on the surface of the interdigitated electrodes. The housing is used to protect the internal components such as the interdigitated electrodes of the gas sensor from corrosion by the external environment, and the electrode leads, pins, interfaces and other components are used for electrical and communication connections with external devices. The above components are appropriately packaged to obtain a gas sensor that can be used in an actual working environment.

[0075] It should be noted that the packaged gas sensor is provided with an opening, and the gas-sensitive layer is connected to the external environment through the opening to achieve detection of the target gas.

[0076] Example

[0077] Zirconia ceramics are selected as the substrate of the gas sensor. Zirconia ceramics are resistant to high temperatures and have excellent stability, which can ensure the stability and insulation of the gas sensor in harsh environments.

[0078] The zirconia ceramic substrate is cleaned, specifically comprising the following steps:

[0079] The substrate was ultrasonically cleaned with acetone, isopropanol, and deionized water in sequence, with each cleaning lasting 5 minutes to remove organic pollutants and impurities on the surface.

[0080] The cleaned substrate was dried at 80° C. for 30 min to ensure that the substrate was completely free of moisture and impurities.

[0081] The interdigital electrodes are prepared on the cleaned substrate, specifically comprising the following steps:

[0082] A silver film is deposited on the surface of the substrate by electron beam evaporation, and the thickness of the deposited silver film is 100 nm.

[0083] The silver film is patterned by photolithography to obtain interdigitated electrodes, and the electrode spacing of the interdigitated electrodes is set to 20 μm to optimize the response speed and sensitivity of the gas sensor.

[0084] The interdigitated electrodes were thermally annealed at 150°C for 1 h.

[0085] After the interdigital electrodes are prepared, a gas-sensitive layer is prepared on the interdigital electrodes by spin coating:

[0086] The LaBO3 nanoparticles were dispersed in ethanol and the LaBO3 nanoparticles in the ethanol were dispersed by ultrasound. The ultrasonic treatment time was 10 min to ensure that the nanoparticles were evenly distributed in the ethanol and to avoid agglomeration.

[0087] The LaBO3 nanoparticle dispersion was evenly coated on the surface of the interdigital electrode by spin coating. The spin coating speed was 2000 rpm and the spin coating time was 30 s to ensure uniform thickness and good adhesion of the gas sensitive layer.

[0088] The interdigitated electrodes coated with the LaBO3 nanoparticle dispersion were dried in an oven at 80°C and then sintered at 400°C for 1 h to obtain a gas sensing layer.

[0089] After the gas-sensitive layer is prepared, the substrate and interdigital electrodes are packaged:

[0090] The substrate, interdigital electrodes and peripheral components are encapsulated using UV curing adhesive, and the peripheral components include the housing, electrode leads, pins and interfaces. The UV curing adhesive is cured under ultraviolet light to achieve adhesion, has excellent high temperature resistance and moisture resistance, and can ensure the stability of the packaging structure in complex environments.

[0091] The encapsulated gas sensor is provided with openings in the gas-sensitive layer area, and the gas-sensitive layer is connected to the external environment through the openings; at the same time, a protective layer is coated around the opening area to reduce non-target responses caused by environmental factors (such as temperature, humidity, other non-target gases, etc.), so that the gas sensor can detect the target gas more accurately; the material of the protective layer can be inorganic materials such as silicon dioxide and aluminum oxide, or organic materials such as polytetrafluoroethylene and polydimethylsiloxane.

[0092] Gas sensor performance test

[0093] The third party of the present application conducted performance tests on the gas sensor provided in the above-mentioned embodiment to explore its specific response to SO2F2 gas and the sensitivity range of detecting SO2F2 gas.

[0094] First, the packaged gas sensor is tested for high temperature and humidity resistance to ensure that components other than the gas-sensitive layer are not damaged in a complex environment, to avoid non-target responses caused by environmental factors and the introduction of noise, and to ensure the accuracy of the measurement results.

[0095] The gas sensor is then placed in a sensor test box, the interdigital electrodes are connected to the data acquisition system through electrode leads, and the electrode leads are ensured to be led out through the packaging area to avoid exposure of the electrode leads to a corrosive gas environment that affects the measurement stability.

[0096] The performance test of the gas sensor includes selectivity test and sensitivity test, as follows:

[0097] 1. Selective testing

[0098] The test gases include SO2, CO2, H2S and NO2, and the concentration is set to 50ppm; among them, SO2, CO2, H2S and NO2 are common target gases in the field of gas detection.

[0099] Inject each gas into the sensor test box separately, measure the response value of the gas sensor to different gases, and record the change of conductivity or resistance value.

[0100] like Figure 2 As shown, the resistance ratio R t / R r Indicates the response value of the gas sensor, R t Indicates the resistance value of the gas sensor after contacting the target gas, R r Indicates the resistance value of the sensor in clean air or reference environment; Figure 2 It can be seen that the gas sensor responds most significantly to SO2F2, while the response to gases such as SO2, CO2, H2S and NO2 is weaker, indicating that the gas sensor has good selectivity for SO2F2.

[0101] 2. Sensitivity test

[0102] SO2F2 gas was introduced into the sensor test box at different concentrations through a gas generator. The concentrations of SO2F2 gas were set to 5ppm, 20ppm, 50ppm, 80ppm and 100ppm, respectively. At room temperature, the response values ​​of the gas sensor to different concentrations of SO2F2 gas were measured, and the conductivity changes after stabilization were recorded.

[0103] like Figure 3 As shown, the conductivity of the gas sensor gradually increases with the increase of SO2F2 gas concentration, and a significant response can be produced at a SO2F2 concentration of 5ppm, indicating that the gas sensor has good sensitivity to low concentration SO2F2 gas.

[0104] It can be seen from the above that the LaBO3 nanoparticles prepared in the embodiment of the present invention have a significant response to SO2F2 gas, filling the gap in the research related to LaBO3 as a SO2F2 gas-sensitive material; since LaBO3 nanoparticles have high sensitivity and fast response speed to SO2F2 gas detection, and LaBO3 materials have good thermal stability and chemical stability, the gas sensor prepared with LaBO3 nanoparticles as the gas-sensitive material is suitable for the effective detection of SO2F2 gas in complex environments; in particular, it can be used for real-time monitoring and detection of SO2F2, the decomposition product of SF6 gas in high-voltage electrical equipment, which is of great significance to ensuring the safe operation of the power system.

[0105] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a LaBO3 gas-sensitive material, characterized in that: The LaBO3 gas-sensitive material is prepared by a sol-gel method, and the preparation method comprises the following steps: S1, adding boric acid and lanthanum nitrate into distilled water, stirring thoroughly to dissolve, and then adding citric acid as a complexing agent to prepare a mixed solution; S2, fully stirring the mixed solution at 60° C. to obtain a sol; S3, drying the sol to obtain a dried gel; S4, calcining the gel at 500° C. to obtain LaBO 3 nanoparticles.

2. The method for preparing LaBO3 gas-sensitive material according to claim 1, characterized in that: The concentration of boric acid in the mixed solution is 0.1M, and the concentration of lanthanum nitrate is 0.1M.

3. The method for preparing the LaBO3 gas-sensitive material according to claim 1, characterized in that: In the step S3, the condition for drying the sol is constant temperature drying at 150°C.

4. The method for preparing the LaBO3 gas-sensitive material according to claim 1, characterized in that: In step S4, the particle size of the LaBO3 nanoparticles is 20-150 nm.

5. A gas sensor, characterized in that: It comprises a substrate, interdigital electrodes arranged on the substrate, and a gas-sensitive layer arranged on the interdigital electrodes; The gas-sensitive layer comprises LaBO3 nanoparticles prepared by the method for preparing the LaBO3 gas-sensitive material according to any one of claims 1-4.

6. The gas sensor according to claim 5, characterized in that: The gas sensor is prepared by the following steps: S5, preparing interdigital electrodes on the substrate; S6, dispersing the LaBO3 nanoparticles in ethanol to obtain a LaBO3 nanoparticle dispersion; S7, using a spin coating method to evenly coat the LaBO3 nanoparticle dispersion on the surface of the interdigital electrode; S8, drying the interdigital electrode coated with the LaBO3 nanoparticle dispersion at 80°C, and then sintering at 400°C to obtain the gas sensing layer.

7. The gas sensor according to claim 6, characterized in that: The step S5 specifically comprises the following steps: S51, depositing a silver thin film on the surface of the substrate by electron beam evaporation; S52, patterning the silver film by photolithography to obtain the interdigital electrodes; S53, performing thermal annealing on the interdigital electrodes, with the thermal annealing temperature being 150°C.

8. The gas sensor according to claim 6, characterized in that: In step S7, the spin coating speed is 2000 rpm and the spin coating time is 30 s.

9. The gas sensor according to claim 6, characterized in that: After step S8, The following steps are involved: S9, encapsulating the substrate and the interdigital electrodes with ultraviolet curing adhesive; the encapsulated gas sensor is provided with an opening, and the gas-sensitive layer is connected to the external environment through the opening.

10. Use of LaBO3 nanoparticles prepared by the method for preparing LaBO3 gas-sensitive material according to any one of claims 1 to 4 in detecting SO2F2 gas, or use of the gas sensor according to any one of claims 5 to 9 in detecting SO2F2 gas.

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