Preparation method of Bi2MoO6 gas sensitive material, gas sensitive sensor and application
Bi2MoO6 nanoparticles were prepared by solvent thermal method and used for gas-sensitive layers of gas-sensitive sensors, which solved the problems of low sensitivity and slow response time of existing NO gas-sensitive sensors, and achieved efficient and rapid detection of NO gas, which was suitable for complex environments. .
Patent Information
- Application Number
- CN202411704517.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-26
- Publication Date
- 2025-02-18
AI Technical Summary
Existing NO gas-sensitive sensors have problems such as low sensitivity, slow response time, and poor performance in high temperature and complex environments, making it difficult to achieve real-time and accurate NO detection.
Bi2MoO6 nanoparticles were prepared by solvothermal method and used for the gas-sensitive layer of the gas-sensitive sensor. Bi2MoO6 nanoparticles were deposited on the surface of the interdigital electrode by electrophoretic deposition to form a gas-sensitive layer with high reactive sites.
Improves the sensitivity and response speed of gas detection. Bi2MoO6 nanoparticles have significant response characteristics and excellent detection sensitivity to low-concentration NO gases, and have good chemical stability and thermal stability. They are suitable for NO in complex environments such as high temperature and high humidity. Gas detection.
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Figure CN119461483A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of gas sensors, and in particular to a preparation method of a Bi2MoO6 gas-sensitive material, a gas-sensitive sensor and applications. Background Art
[0002] Nitrogen monoxide (NO) is one of the main by-products of industrial production, motor vehicle emissions and fossil fuel combustion, which can have adverse effects on the atmospheric environment and human health. Monitoring and controlling NO emissions is crucial to environmental protection and public health.
[0003] Currently, the gas-sensitive materials of NO gas sensors are usually metal oxide semiconductor materials such as tin dioxide, tungsten oxide, zinc oxide, or some conductive polymer materials with specific responses. However, these NO gas sensors usually have defects such as low sensitivity, slow response time, and poor performance under high temperature and complex environments. Therefore, developing a sensor material with high sensitivity, fast response, and adaptability to complex environments to achieve real-time and accurate NO detection has become a key technical issue. Summary of the invention
[0004] The present invention provides a preparation method of a Bi2MoO6 gas-sensitive material, a gas-sensitive sensor and applications, aiming at efficiently detecting NO gas.
[0005] The Bi2MoO6 gas-sensitive material provided by the present invention is prepared by a solvent thermal method, and the preparation method comprises the following steps:
[0006] S1, dissolving bismuth nitrate and sodium molybdate in dimethyl sulfoxide, adding polyethylene glycol as a dispersant, and stirring to obtain a reaction solution;
[0007] S2, placing the reaction solution into a reaction kettle, sealing and reacting at 200° C. for 10 h to obtain Bi2MoO6 nanoparticles;
[0008] S3, washing and drying the Bi2MoO6 nanoparticles.
[0009] Optionally, the concentration of bismuth nitrate in the reaction solution is 0.1M, and the concentration of sodium molybdate is 0.1M.
[0010] Optionally, the step S3 specifically includes the following steps:
[0011] S31, washing the Bi2MoO6 nanoparticles obtained in step S2 with ethanol;
[0012] S32, drying the Bi2MoO6 nanoparticles at 60°C.
[0013] Optionally, the particle size of the Bi2MoO6 nanoparticles is 20-300 nm.
[0014] 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;
[0015] The gas-sensitive layer comprises Bi2MoO6 nanoparticles prepared by the above-mentioned method for preparing the Bi2MoO6 gas-sensitive material.
[0016] Optionally, the gas sensor is prepared by the following steps:
[0017] S4, preparing interdigital electrodes on the substrate;
[0018] S5, dispersing the Bi2MoO6 nanoparticles in a mixed solution of ethanol and acetone, and adjusting the mixed solution to a preset pH value;
[0019] S6, placing the substrate and the interdigital electrodes obtained in step S4 in the mixed solution, and depositing the Bi2MoO6 nanoparticles on the surface of the interdigital electrodes by electrophoretic deposition;
[0020] S7, drying and sintering the interdigital electrode deposited with the Bi2MoO6 nanoparticles at 150°C to obtain the gas sensing layer.
[0021] Optionally, the step S4 specifically includes the following steps:
[0022] S41, preparing a rhodium thin film on the substrate by physical vapor deposition;
[0023] S42, patterning the rhodium film by laser etching to obtain the interdigitated electrodes;
[0024] S43, thermally annealing the interdigital electrodes at 200°C.
[0025] Optionally, in step S6, the deposition voltage of the electrophoretic deposition is 50 V, and the deposition time is 3 min.
[0026] Optionally, after step S7, the following steps are also included:
[0027] S8, encapsulating the substrate and the interdigital electrodes with organic silica gel; the encapsulated gas sensor is provided with an opening, and the gas-sensitive layer is connected to the external environment through the opening.
[0028] The present invention also proposes the use of the above-mentioned Bi2MoO6 gas-sensitive material or gas-sensitive sensor in detecting NO gas.
[0029] The present invention has the following beneficial effects:
[0030] The present invention adopts a solvothermal method to prepare Bi2MoO6 nanoparticles with a small particle size, relatively uniform dispersion and abundant surface structural defects. The specific surface area of the Bi2MoO6 nanoparticles is significantly increased, and more reactive sites can be provided, thereby enhancing the sensitivity and response speed of gas detection. Selectivity tests and sensitivity tests are performed on the Bi2MoO6 nanoparticles prepared by the present invention, and it is found that the Bi2MoO6 nanoparticles have significant response characteristics and excellent detection sensitivity to low-concentration NO gas, and the Bi2MoO6 nanoparticles have good chemical stability and thermal stability. The gas sensor using the Bi2MoO6 nanoparticles as the gas-sensitive material is suitable for the detection of NO gas in complex environments such as high temperature and high humidity. BRIEF DESCRIPTION OF THE DRAWINGS
[0031] 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.
[0032] Figure 1 This is a microscopic morphology structure diagram of Bi2MoO6 nanoparticles prepared by the present invention;
[0033] Figure 2 is a histogram of the response characteristics of the gas sensor of the present invention to different gases;
[0034] Figure 3 The graph is a response curve of the gas sensor of the present invention to NO gas of different concentrations. DETAILED DESCRIPTION
[0035] 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.
[0036] After intensive research, the inventors of the present application discovered that a Bi2MoO6 nanoparticle with a small particle size and uniform dispersion can be prepared by a specific method. The Bi2MoO6 nanoparticle has a significant response to NO gas and can be used to efficiently detect NO gas, providing a new solution for NO gas detection.
[0037] Preparation method of Bi2MoO6 gas sensitive material
[0038] The first aspect of the present application provides a method for preparing a Bi2MoO6 gas-sensitive material, wherein the Bi2MoO6 gas-sensitive material is prepared by a solvent thermal method, and specifically comprises the following steps:
[0039] S1, dissolving bismuth nitrate and sodium molybdate in dimethyl sulfoxide, adding polyethylene glycol as a dispersant, and stirring to obtain a reaction solution.
[0040] In this step, dimethyl sulfoxide (DMSO) as a polar solvent is beneficial to dissolve bismuth nitrate and sodium molybdate, and promotes the growth of Bi2MoO6 crystals in the subsequent solvothermal synthesis of Bi2MoO6 nanoparticles.
[0041] Furthermore, in order to control the particle size and dispersibility of Bi2MoO6 nanoparticles, polyethylene glycol (PEG) was added to the reaction solution as a dispersant.
[0042] Specifically, PEG molecules provide a certain viscous environment in the reaction solution, impose certain restrictions on the growth of Bi2MoO6 nanoparticles in the solvothermal reaction, slow down the growth rate of the nanoparticles, and thus obtain nanoparticles with a moderate particle size; on the other hand, PEG molecules can be adsorbed on the surface of Bi2MoO6 nanoparticles, effectively inhibiting the agglomeration of nanoparticles through the steric hindrance effect, and helping to form highly dispersed nanoparticles during the solvothermal reaction; the added concentration and molecular weight of PEG can be reasonably selected according to the concentrations of bismuth nitrate and sodium molybdate in the reaction solution and the particle size of the target Bi2MoO6 nanoparticles.
[0043] S2, the reaction solution is loaded into a reactor, and the reaction is sealed at 200° C. for 10 h to obtain Bi2MoO6 nanoparticles.
[0044] In this step, bismuth nitrate and sodium molybdate in the mixed solution react in a sealed reactor to generate Bi2MoO6 nanoparticles; the particle size and dispersion of the nanoparticles can be optimized by controlling the reaction temperature and reaction time. For example, reacting at a lower temperature can slow down the growth rate of the crystal nucleus, so that the generated nanoparticles have a smaller particle size and a more uniform distribution.
[0045] S3, washing and drying the Bi2MoO6 nanoparticles.
[0046] In this step, the purpose of washing and drying the Bi2MoO6 nanoparticle product is to remove solvent residues and reaction by-products (such as sodium salt).
[0047] In one embodiment, ethanol can be used to clean the Bi2MoO6 nanoparticles. Ethanol does not react with Bi2MoO6 and can be easily dried and removed.
[0048] Example
[0049] 0.1 M bismuth nitrate (Bi(NO3)3) and 0.1 M sodium molybdate (Na2MoO4) were dissolved in dimethyl sulfoxide (DMSO), polyethylene glycol was added as a dispersant, and the mixture was stirred thoroughly to obtain a reaction solution.
[0050] The reaction solution was added into a reactor and sealed, and reacted at 200°C for 10 h to obtain highly dispersed Bi2MoO6 nanoparticles.
[0051] The obtained Bi2MoO6 nanoparticles are washed with ethanol for multiple times, for example, 2-5 times, and then dried at 60°C to remove solvent residues and reaction by-products, thereby preparing target Bi2MoO6 nanoparticles.
[0052] like Figure 1 As shown, the Bi2MoO6 nanoparticles prepared in this embodiment have a smaller particle size (particle size is 20-300nm) and better dispersibility without serious clustering; in addition, the surface structure of the Bi2MoO6 nanoparticles prepared in this embodiment is irregular, forming abundant surface structural defects.
[0053] The Bi2MoO6 nanoparticles prepared in this embodiment have excellent gas adsorption capacity. The adsorbed gas molecules, such as NO molecules, will undergo redox reactions with the active sites on the Bi2MoO6 nanoparticles, causing a change in the carrier concentration on the surface of the nanoparticles. This change changes the conductivity of the nanoparticles. The Bi2MoO6 nanoparticles are prepared into the gas-sensitive layer of a gas sensor, and the presence of NO gas can be detected and the concentration of NO gas can be accurately reflected by measuring the change in the conductivity of the gas-sensitive layer.
[0054] The Bi2MoO6 nanoparticles prepared in this embodiment have a small particle size and are evenly dispersed, and have a large specific surface area, which can provide more active sites for gas detection (such as lattice defects, oxygen vacancy defects, metal ion active sites, etc.) that can react, thereby enhancing the sensitivity of gas detection; and the irregular surface structure forms abundant structural defects and spatial sites, thereby increasing the active sites for gas detection, further enhancing the sensitivity of gas detection; the active sites of the Bi2MoO6 nanoparticles are highly matched with the size and shape of the NO gas molecules, so that the NO gas molecules can rapidly undergo redox reactions after being adsorbed onto the surface of the Bi2MoO6 nanoparticles, resulting in a change in conductivity, and can thus be used as a gas-sensitive material to achieve efficient detection of NO gas.
[0055] Gas Sensor
[0056] Based on the Bi2MoO6 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 Bi2MoO6 nanoparticles prepared in the above-mentioned preparation method embodiment.
[0057] The gas sensor is prepared by the following steps:
[0058] S4, preparing interdigitated electrodes on a substrate.
[0059] 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.
[0060] The preparation of the interdigital electrodes on the substrate specifically includes the following steps S41-S43:
[0061] S41, preparing a rhodium thin film on a substrate using physical vapor deposition.
[0062] Specifically, metal rhodium has good conductivity and strong antioxidant ability, which can improve the durability of the interdigital electrodes and enhance the reliability of the gas sensor in long-term use.
[0063] It should be noted that this step may also use other conductive materials with good conductivity and environmental stability instead of the rhodium 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 rhodium film may also be adjusted according to the actual conductive material selected.
[0064] S42, patterning the rhodium film using laser etching to obtain interdigitated electrodes.
[0065] Specifically, the rhodium film is etched with laser with high processing accuracy, and the electrode spacing of the interdigitated electrodes can be defined with high precision, thereby improving the detection accuracy of the airtight sensor and the sensitivity of the gas detection area.
[0066] S43, thermally annealing the interdigital electrodes at 200°C.
[0067] Specifically, thermal annealing of the interdigital electrodes made of rhodium thin film at 200° C. can enhance the bonding force and electrical conductivity between the interdigital electrodes and the substrate.
[0068] After the interdigital electrodes are prepared on the substrate, a gas-sensitive layer is prepared on the surface of the interdigital electrodes by electrophoretic deposition, which specifically includes the following steps:
[0069] S5, dispersing the Bi2MoO6 nanoparticles prepared in the above preparation method example in a mixed solution of ethanol and acetone, and adjusting the mixed solution to a preset pH value.
[0070] Specifically, Bi2MoO6 nanoparticles are easily attracted to each other and agglomerated due to their small size and high surface energy; ethanol and acetone as organic solvents can be adsorbed on the surface of the nanoparticles, isolating the nanoparticles from each other, thereby maintaining a good dispersion state, which is beneficial to the uniform migration of the nanoparticles in the subsequent electrophoretic deposition step.
[0071] In this step, the viscosity and surface tension of the mixed solution can be adjusted by controlling the ratio of ethanol and acetone to reach a range suitable for electrophoresis, so that the nanoparticles can better contact and deposit on the electrode surface, thereby improving the adhesion and uniformity of the deposited layer.
[0072] In this step, the charge of the nanoparticles can be increased by adjusting the pH value of the mixed solution.
[0073] S6, placing the substrate and the interdigital electrodes obtained in step S4 in a mixed solution, and depositing Bi2MoO6 nanoparticles on the surfaces of the interdigital electrodes by electrophoretic deposition.
[0074] Specifically, by applying a direct current electric field, charged Bi2MoO6 nanoparticles are deposited on the surface of the interdigitated electrode to form a uniform gas-sensitive layer; electrophoretic deposition can avoid agglomeration of nanoparticles as much as possible, and the deposited gas-sensitive layer has good uniformity.
[0075] S7, drying and sintering the interdigitated electrode deposited with Bi2MoO6 nanoparticles at 150°C to obtain the target gas sensing layer.
[0076] Specifically, drying and sintering the gas sensor at 150° C. can make the gas-sensitive layer structure more compact and further improve the stability of the gas sensor.
[0077] S8, using organic silicone to encapsulate the substrate and interdigital electrodes.
[0078] 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.
[0079] In this step, the chemical properties of organic silicone are stable, and it is not easily corroded by chemical substances such as acids, alkalis, and salts. It is resistant to both high and low temperatures and can maintain stable performance over a wide temperature range. In addition, after curing, organic silicone has good elasticity and flexibility and can adapt to different installation environments and usage conditions. Therefore, as a packaging material, it can enhance the adaptability of gas sensors in complex environments, especially for a variety of scenarios for NO gas detection, such as chemical production, electronics industry, automobile exhaust detection, environmental monitoring, scientific experimental research, etc.
[0080] 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 ensure that the detected gas can directly contact the airtight layer.
[0081] Example
[0082] Alumina ceramics are selected as the substrate, which has good thermal stability and electrical insulation.
[0083] The substrate was ultrasonically cleaned with acetone, ethanol and deionized water in sequence, with each cleaning time of 5 min to thoroughly remove impurities on the substrate surface.
[0084] The cleaned substrate was dried at 100 °C for 30 min to ensure that no moisture remained, which was beneficial to the stability of electrode deposition.
[0085] A rhodium film is deposited on the substrate surface using a physical vapor deposition (PVD) process, and the pattern of the interdigitated electrodes is defined with high precision using laser etching technology. The patterned rhodium film is used to obtain the interdigitated electrodes, and the electrode spacing is set to 10μm to ensure the sensitivity of the gas detection area.
[0086] After the interdigital electrodes were prepared, they were annealed at 200°C for 1 h to enhance the bonding strength and conductivity between the interdigital electrodes and the substrate.
[0087] The Bi2MoO6 nanoparticles prepared in the above-mentioned preparation method example are dispersed in a mixed solution of ethanol and acetone, and the pH value of the mixed solution is adjusted to 4 to increase the charge of the nanoparticles.
[0088] The electrophoretic deposition method was used to deposit charged Bi2MoO6 nanoparticles on the surface of the interdigitated electrode to form a uniform gas-sensitive layer by applying a DC electric field. The deposition voltage was set to 50 V and the deposition time was controlled at 3 min to ensure that the thickness of the gas-sensitive layer was uniform.
[0089] After the gas-sensitive layer is deposited, the substrate and the interdigital electrodes are dried and sintered at 150°C for 1 h to make the gas-sensitive layer structure dense and provide detection stability for the gas sensor.
[0090] Organic silicone is used to encapsulate the substrate, interdigital electrodes and outer shell, electrode leads, pins, interfaces and other peripheral components to prevent interference from moisture and impurities in complex environments. During packaging, openings are reserved above the gas-sensitive layer to ensure that the detected gas can directly contact the gas-sensitive layer through the openings.
[0091] Gas sensor performance test
[0092] 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 NO gas and the sensitivity range of detecting NO gas.
[0093] Before conducting performance testing, the gas sensor is first placed in a sensor test box. The gas sensor is connected to the data acquisition system through electrode leads, where the electrode leads are isolated from the influence of the detection gas by the packaging layer to ensure the reliability of data transmission.
[0094] The performance test of the gas sensor includes selectivity test and sensitivity test, as follows:
[0095] 1. Selective testing
[0096] The purpose of the selectivity test is to verify the specific response of the gas sensor to NO gas.
[0097] The test gases include NO, SF6, SO2, CO2, H2S and NO2, with a concentration of 50ppm. Each gas is injected into the sensor test box respectively, and the response value of the gas sensor to each gas is measured respectively.
[0098] like Figure 2 As shown, the response value can be expressed as the resistance ratio Rt / Rr, where Rt represents the resistance value of the gas sensor after contacting the detection gas, and Rr represents the resistance value of the gas sensor in clean air or a reference environment. The response value of the gas sensor to NO gas is significantly higher than that to other gases, which indicates that the gas sensor has good selectivity for NO. In practical applications, the response to interfering gases such as SF6, SO2, CO2, H2S and NO2 is weak.
[0099] 2. Sensitivity test
[0100] The purpose of the sensitivity test is to verify the response of the gas sensor to different concentrations of NO gas in order to evaluate its detection sensitivity.
[0101] NO gas is injected into the sensor test box at different concentrations through a gas generator. The concentrations can be set to 10ppm, 20ppm, 50ppm, 100ppm and 200ppm respectively. The conductivity of the gas sensor at different NO gas concentrations is measured and recorded.
[0102] like Figure 3 As shown, the test results show that the conductivity of the gas sensor increases with the increase of NO gas concentration. At a concentration of 10ppm, the gas sensor can produce a significant response, indicating that the gas sensor has a high detection sensitivity to NO gas.
[0103] In addition, in further tests, the gas sensor can respond quickly to low concentrations of NO gas (such as 10ppm), with a response time as short as 3min, and has good linear response characteristics; after multiple cycle tests on the gas sensor, it can still maintain stable gas-sensitive performance, and has the ability to recover quickly in high temperature and high humidity environments, and has good detection stability.
[0104] As can be seen from the above, the Bi2MoO6 nanoparticles prepared in the embodiment of the present invention have a significant specific response to NO gas, providing a new solution for NO gas detection; the Bi2MoO6 nanoparticles are small in size and evenly dispersed, and have abundant surface structural defects, which can provide more active sites for NO gas detection, enhancing the sensitivity and response speed of gas detection; therefore, the gas sensor prepared with Bi2MoO6 nanoparticles as gas-sensitive materials can efficiently detect NO gas. In addition, the Bi2MoO6 nanoparticles have good chemical stability and thermal stability. Further, by selecting and designing the sensor substrate, interdigital electrodes, and packaging materials, the gas sensor provided in the embodiment of the present invention is suitable for effective and stable detection of NO gas in complex environments such as high temperature and high humidity, which greatly expands the application scenarios of NO gas detection and is of great significance to industrial production, environmental protection, and scientific research.
[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 Bi2MoO6 gas-sensitive material, characterized in that: The Bi2MoO6 gas-sensitive material is prepared by a solvothermal method, and the preparation method comprises the following steps: S1, dissolving bismuth nitrate and sodium molybdate in dimethyl sulfoxide, adding polyethylene glycol as a dispersant, and stirring to obtain a reaction solution; S2, placing the reaction solution into a reaction kettle, sealing and reacting at 200° C. for 10 h to obtain Bi2MoO6 nanoparticles; S3, washing and drying the Bi2MoO6 nanoparticles.
2. The method for preparing the Bi2MoO6 gas-sensitive material according to claim 1, characterized in that: The concentration of bismuth nitrate in the reaction solution is 0.1M, and the concentration of sodium molybdate is 0.1M.
3. The method for preparing the Bi2MoO6 gas-sensitive material according to claim 1, characterized in that: The step S3 specifically comprises the following steps: S31, washing the Bi2MoO6 nanoparticles obtained in step S2 with ethanol; S32, drying the Bi2MoO6 nanoparticles at 60°C.
4. The method for preparing the Bi2MoO6 gas-sensitive material according to claim 1, characterized in that: The particle size of the Bi2MoO6 nanoparticles is 20-300nm.
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 Bi2MoO6 nanoparticles prepared by the preparation method of Bi2MoO6 gas-sensitive material according to any one of claims 1 to 4.
6. The gas sensor according to claim 5, characterized in that: The gas sensor is prepared by the following steps: S4, preparing interdigital electrodes on the substrate; S5, dispersing the Bi2MoO6 nanoparticles in a mixed solution of ethanol and acetone, and adjusting the mixed solution to a preset pH value; S6, placing the substrate and the interdigital electrodes obtained in step S4 in the mixed solution, and depositing the Bi2MoO6 nanoparticles on the surface of the interdigital electrodes by electrophoretic deposition; S7, drying and sintering the interdigital electrode deposited with the Bi2MoO6 nanoparticles at 150°C to obtain the gas sensing layer.
7. The gas sensor according to claim 6, characterized in that: The step S4 specifically comprises the following steps: S41, preparing a rhodium thin film on the substrate by physical vapor deposition; S42, patterning the rhodium film by laser etching to obtain the interdigitated electrodes; S43, thermally annealing the interdigital electrodes at 200°C.
8. The gas sensor according to claim 6, characterized in that: In step S6, the deposition voltage of the electrophoretic deposition is 50 V, and the deposition time is 3 min.
9. The gas sensor according to claim 6, characterized in that: After step S7, the method further includes the following steps: S8, encapsulating the substrate and the interdigital electrodes with organic silica gel; 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 Bi2MoO6 nanoparticles prepared by the method for preparing Bi2MoO6 gas-sensitive material according to any one of claims 1 to 4 in detecting NO gas, or use of the gas sensor according to any one of claims 5 to 9 in detecting NO gas.