Methane sensor for room temperature detection and detection method thereof

Abstract

The application discloses a kind of methane sensors and its detection method of room temperature detection, belong to methane detection technical field.To solve the problem of high temperature of methane sensor operation.This application glass fiber epoxy resin composite substrate, Au interdigital electrode, Ag doped NH2-C3N4 / CoAl-LDO nano sensing material layer, double-row needle structure device I;Support, double-row female, battery, ultraviolet lamp, resistance acquisition chip, bluetooth module constitute device II;Double-row female, resistance acquisition chip, bluetooth module, battery are sequentially installed on the bottom plate of the support from left to right, one end of double-row female is connected with resistance acquisition chip, and the resistance acquisition chip is connected with bluetooth module;The ultraviolet lamp is installed on the top plate of the support;Device I is placed below the ultraviolet lamp, and the other end of double-row female of device I is connected with double-row female, and battery acts as the overall power supply of a kind of methane sensor of room temperature detection.

Description

Technical Field

[0001] This invention belongs to the field of methane detection technology, specifically relating to a room temperature methane sensor and its detection method. Background Technology

[0002] With the global trend towards a cleaner and lower-carbon energy structure, natural gas, as a highly efficient and low-pollution fossil fuel, has seen its production, storage, transportation, and application scale continuously expand, becoming one of the core energy sources in industrial production, urban heating, residential life, and power generation. Methane, as the main component of natural gas (accounting for over 90%), has become an ideal alternative to traditional high-pollution energy sources due to its high combustion efficiency and low pollutant emissions. However, methane is inherently colorless, odorless, flammable, and explosive, with an explosive limit of 5% to 15% (volume fraction) in air. In scenarios such as natural gas pipeline transportation, coal mining, petrochemical production, and household gas use, leaks are prone to occur due to factors such as pipeline aging and corrosion, equipment sealing failure, and improper operation. Methane leaks not only cause significant energy waste but can also trigger major safety accidents such as explosions and fires, seriously threatening human life and property. Furthermore, as a potent greenhouse gas, methane leaks and emissions exacerbate global warming, causing long-term impacts on the ecological environment. Therefore, developing highly sensitive, real-time-response, and reliable methane detection technologies is crucial to ensuring the safe and efficient use of methane and reducing environmental risks.

[0003] Currently, methane sensors on the market can be classified into catalytic combustion type, metal oxide semiconductor type, optical type, and electrochemical type according to their detection principles. Among them, catalytic combustion type and metal oxide semiconductor type sensors have become mainstream products in industrial and civilian scenarios due to their simple structure and low cost. However, both types of sensors have significant technical bottlenecks: (1) High operating temperature requirements. Catalytic combustion type sensors need to achieve methane catalytic combustion at a high temperature of 300~500℃, and metal oxide semiconductor type sensors also need a heating temperature of 200~400℃ to activate the activity of the sensing material. Both require additional integration of micro heating modules, resulting in complex sensor processes and high energy consumption, making it difficult to adapt to portable, low-power detection devices and special scenarios where heating is not possible; (2) Insufficient activity of sensing materials at room temperature. Not only is the response sensitivity low and the detection lower limit difficult to meet the requirements of low-concentration leakage early warning, but there are also problems such as slow desorption of methane molecules and slow recovery speed, which affect the efficiency of sensor recycling; (3) Although optical type sensors have high detection accuracy, they have problems such as high cost, large size, and complex maintenance, which limit their large-scale application. Therefore, developing a room temperature methane sensor that requires no high-temperature heating, consumes little energy, has a compact structure, and combines high sensitivity with rapid recovery performance has become an urgent direction to overcome the limitations of existing technologies and meet the needs of practical applications. Summary of the Invention

[0004] The problem to be solved by the present invention is to overcome the shortcomings of existing methane sensors, such as high operating temperature, high energy consumption and slow recovery speed, and to propose a room temperature methane sensor and its detection method.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A methane sensor for room temperature detection includes a glass fiber epoxy resin composite substrate, Au interdigitated electrodes, Ag-doped NH2-C3N4 / CoAl-LDO nanosensing material layer, a double row of pin headers, a support, a double row of female headers, a battery, an ultraviolet lamp, a resistance acquisition chip, and a Bluetooth module. The device I consists of a glass fiber epoxy resin composite substrate, Au interdigitated electrodes, an Ag-doped NH2-C3N4 / CoAl-LDO nanosensing material layer, and a double-row pin header. Au interdigitated electrodes are prepared on the surface of the glass fiber epoxy resin composite substrate by chemical deposition. An Ag-doped NH2-C3N4 / CoAl-LDO nanosensing material layer is uniformly coated on the sensing area of ​​the Au interdigitated electrodes. The leads of the Au interdigitated electrodes are connected to a double-row pin header. The preparation method of the Ag-doped NH2-C3N4 / CoAl-LDO nanosensing material layer is as follows: 0.5~50mg of Ag-doped NH2-C3N4 / CoAl-LDO nanosensing material is ultrasonically dispersed in 5 times the volume of ethanol solution to prepare a suspension. The suspension is uniformly coated on the sensing area of ​​the Au interdigitated electrode (2). After drying at 60~70℃ for 2~3h, the modification of the sensing material is completed. The support, double-row connector, battery, ultraviolet lamp, resistance acquisition chip, and Bluetooth module constitute device II. The double-row connector, resistance acquisition chip, Bluetooth module, and battery are installed sequentially from left to right on the base plate of the support. One end of the double-row connector is connected to the resistance acquisition chip, and the resistance acquisition chip is connected to the Bluetooth module. The ultraviolet lamp is installed on the top plate of the support. Device I is placed below the ultraviolet lamp, and the double-row connector of device I is connected to the other end of the double-row connector. The battery provides overall power to a room temperature methane sensor.

[0006] Furthermore, the Au interdigitated electrode has a finger width of 0.05mm~0.5mm, a finger spacing of 0.05mm~0.5mm, a finger pair count of 30~50, a sensing area of ​​2mm×4mm~15mm×20mm, and an electrode thickness of 0.02μm~0.1μm.

[0007] Furthermore, the support consists of a top plate and a bottom plate that are double-layered copper-clad laminates, with the top plate and bottom plate connected by multiple hexagonal copper pillars to form a cuboid cavity shape.

[0008] Furthermore, the ultraviolet lamp vertically irradiates the Ag-doped NH2-C3N4 / CoAl-LDO nanosensor material layer.

[0009] Furthermore, the preparation method of the Ag-doped NH2-C3N4 / CoAl-LDO nanosensor material includes the following steps: Step 1. Preparation of graphitic carbon nitride C3N4: Take a certain mass of melamine and spread it evenly in a porcelain boat; put the porcelain boat into a muffle furnace, set the heating rate to 5~10℃ / min and heat to 500℃, and calcine at a constant temperature of 500℃ in air for 4 hours; after the muffle furnace cools naturally to room temperature, take out the calcined product and grind it thoroughly into a fine powder with a mortar and pestle to obtain graphitic carbon nitride C3N4; Step 2. Amine-modified carbon nitride (NH) 2- Preparation of C3N4: Measure 30 mL of ammonia water and 90 mL of anhydrous ethanol into a beaker, stir evenly to prepare a mixed solvent; weigh 1 g of C3N4 powder obtained in step 1 and add it to the mixed solvent, sonicate until the powder is completely dispersed, transfer the dispersion to a three-necked flask, place it in a 70℃ constant temperature oil bath, and react at a constant temperature for 10-12 hours; after the reaction is completed, cool to room temperature and perform vacuum filtration; place the filter cake in a vacuum oven and dry at 60℃ for 24 hours, grind after drying to obtain NH2-C3N4 powder for later use; Step 3. Preparation of CoAl-LDHs: Weigh 0.8 mmol of cobalt nitrate hexahydrate, 0.4 mmol of aluminum nitrate nonahydrate, 4 mmol of ammonium fluoride, and 28 mmol of urea, and add them sequentially to a beaker containing 35 mL of deionized water. Stir magnetically for 1 hour until all solid reagents are completely dissolved, forming a clear and transparent precursor solution. Transfer the precursor solution to a hydrothermal reactor lined with polytetrafluoroethylene, seal it, and place it in a forced-air drying oven. Heat at 90°C for 6-8 hours. After the reaction is complete, allow the reactor to cool naturally to room temperature, open the reactor, and perform vacuum filtration. Place the filter cake in a vacuum oven and dry at 60°C for 24 hours to obtain CoAl-LDHs powder for later use. Step 4. Preparation of CoAl-LDO: Weigh the CoAl-LDHs powder obtained in Step 3 and spread it evenly in a porcelain boat; place the porcelain boat in a muffle furnace and calcine at a constant temperature of 500℃ for 4 hours; after the muffle furnace cools naturally to room temperature, take out the product, grind it evenly to obtain CoAl-LDO powder, and collect it for later use. Step 5. Preparation of NH2-C3N4 / CoAl-LDO composite material: Measure 50 mL of deionized water into a beaker, add 0.5 g of NH2-C3N4 powder obtained in step 2 and 1 g of CoAl-LDO powder obtained in step 4, and then add 0.015 g of polyvinylpyrrolidone; sonicate until the powder is completely dispersed, and then magnetically stir for 4 hours to obtain a mixture; transfer the mixture to a centrifuge tube and centrifuge at 8000 r / min; collect the solid product after centrifugation, put it in a vacuum oven, dry at 60℃ for 24 hours, grind it to obtain NH2-C3N4 / CoAl-LDO composite material for later use; Step 6. Preparation of Ag-doped NH2-C3N4 / CoAl-LDO composite material: Measure 50 mL of deionized water into a beaker, add 1 g of the NH2-C3N4 / CoAl-LDO composite material obtained in step 5, and ultrasonically disperse until a uniform suspension is formed; add 0.05~2.5 wt% silver nitrate solution and ascorbic acid at 3 times the mass of silver nitrate to the suspension in sequence; add KOH solution dropwise to adjust the pH value of the system to 8~9, and then transfer to a water bath and react at 40℃ for 12~16 hours; after the reaction is completed, centrifuge at 8000 r / min to separate and collect the solid product; put the product into a vacuum oven and dry at 40℃ for 24 hours, and grind to obtain the Ag-doped NH2-C3N4 / CoAl-LDO composite material.

[0010] Furthermore, the Bluetooth module connects to an external terminal.

[0011] A method for retrieving methane using a room temperature detection sensor includes the following steps: S1. Connect the battery power supply, turn on the ultraviolet lamp for preheating for 5 minutes, and use the resistance acquisition chip to collect the baseline resistance R of the Ag-doped NH2-C3N4 / CoAl-LDO composite material layer in air. a ; S2. The room-temperature methane sensor is placed in a methane-containing detection environment. Methane gas diffuses to and adsorbs onto the surface of the Ag-doped NH2-C3N4 / CoAl-LDO nanosensor material layer. Under ultraviolet light excitation, methane molecules are activated, causing a change in the resistance of the Ag-doped NH2-C3N4 / CoAl-LDO nanosensor material layer. The resistance acquisition chip captures this changed resistance R in real time. g ; S3. The response value is calculated as follows: According to the linear fitting equation x is the concentration of methane in the gas to be tested (ppm), and y is the response value. The methane concentration x is deduced from the detected response value y and transmitted to an external terminal via Bluetooth module to achieve quantitative detection. S4. After the detection is completed, the ultraviolet lamp continues to irradiate to promote the desorption of residual gas on the surface of the Ag-doped NH2-C3N4 / CoAl-LDO nanosensor material layer, and the sensor returns to the baseline state for the next detection.

[0012] The beneficial effects of this invention are: This invention discloses a room-temperature methane sensor. Through the synergistic effect of the three-dimensional layered structure of Ag-doped NH₂-C₃N₄ / CoAl-LDO nanomaterials, Ag catalytic sites, and heterojunction interfaces, combined with ultraviolet (UV) irradiation activation, methane molecule activation and rapid reaction can be achieved without high-temperature heating, solving the problems of high energy consumption and poor room-temperature response of existing sensors. UV light not only provides energy for the breaking of carbon-hydrogen bonds in methane molecules but also promotes gas desorption on the surface of the sensing material, significantly improving the sensor's recovery speed and ensuring efficient recycling. In the methane concentration range of 2000 ppm to 500 ppm, this sensor not only exhibits high sensitivity at room temperature but also demonstrates a rapid recovery speed (recovery time less than 200 s). The linearly fitted detection equation is as follows: (x represents the concentration of methane in the gas being tested, in ppm; y represents the response). The detection limit for methane reaches 500 ppm, and the linear correlation coefficient reaches 0.92899. A double-layer copper-clad laminate substrate integrates the data processing module and sensing unit, resulting in a compact structure. Combined with Bluetooth wireless transmission, it enables portable real-time detection. The overall process is simple and cost-effective, suitable for various scenarios such as industrial leak early warning and residential gas detection, with broad application prospects. Attached Figure Description

[0013] Figure 1 A three-dimensional structural schematic diagram of a methane sensor for room temperature detection provided by the present invention; Figure 2 SEM images of Ag-doped C3N4 / CoAl-LDO nanosensor materials prepared in Example 1; Figure 3 The XRD pattern of the Ag-doped C3N4 / CoAl-LDO nanosensor material prepared in Example 1; Figure 4 The dynamic sensing response of the room temperature methane sensor based on Ag-doped NH2-C3N4 / CoAl-LDO prepared in Example 1 to 500ppm~2000ppm methane gas is shown in the figure. Figure 5 The repeatability test diagram of the room temperature methane sensor based on Ag-doped NH2-C3N4 / CoAl-LDO prepared in Example 1 for 2000ppm methane gas. Figure 6The linear fitting curve of the response value of the room temperature methane sensor based on Ag-doped NH2-C3N4 / CoAl-LDO prepared in Example 1 to methane gas from 500ppm to 2000ppm is shown. Figure 7 This is a schematic diagram of the structure of device I; Figure 8 This is a schematic diagram of the structure of device II; In the figure, 1 is the glass fiber epoxy resin composite substrate; 2 is the Au interdigitated electrode; 3 is the Ag-doped NH2-C3N4 / CoAl-LDO nanosensor material layer; 4 is the double row of pin headers; 5 is the cuboid cavity of the copper-clad laminate; 6 is the double row of pin headers; 7 is the battery; 8 is the ultraviolet lamp; 9 is the resistance acquisition chip; and 10 is the Bluetooth module. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described specific embodiments are merely a part of the embodiments of the invention, and not all of them. The components of the specific embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations, and the invention may also have other embodiments.

[0015] Therefore, the following detailed description of specific embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected specific embodiments of the invention. All other specific embodiments obtained by those skilled in the art based on these specific embodiments without inventive effort are within the scope of protection of this invention.

[0016] To further understand the invention's content, features, and effects, the following specific embodiments are provided, along with accompanying drawings. Figure 1 - Appendix Figure 8 Detailed explanation is as follows:

[0017] Example 1: This embodiment provides a room temperature methane sensor, including a glass fiber epoxy resin composite substrate 1, an Au interdigitated electrode 2, an Ag-doped NH2-C3N4 / CoAl-LDO nanosensing material layer 3, a double row of pins 4, a support 5, a double row of sockets 6, a battery 7, an ultraviolet lamp 8, a resistance acquisition chip 9, and a Bluetooth module 10. The device I consists of a glass fiber epoxy resin composite substrate 1, an Au interdigitated electrode 2, an Ag-doped NH2-C3N4 / CoAl-LDO nanosensing material layer 3, and a double-row pin header 4. The Au interdigitated electrode 2 is prepared on the surface of the glass fiber epoxy resin composite substrate 1 by chemical deposition. The Ag-doped NH2-C3N4 / CoAl-LDO nanosensing material layer 3 is uniformly coated on the sensing area of ​​the Au interdigitated electrode 2. The leads of the Au interdigitated electrode 2 are connected to the double-row pin header 4. The support 5, double-row connector 6, battery 7, ultraviolet lamp 8, resistance acquisition chip 9, and Bluetooth module 10 constitute device II. The double-row connector 6, resistance acquisition chip 9, Bluetooth module 10, and battery 7 are installed sequentially from left to right on the base plate of the support 5. One end of the double-row connector 6 is connected to the resistance acquisition chip 9, and the resistance acquisition chip 9 is connected to the Bluetooth module 10. The ultraviolet lamp 8 is installed on the top plate of the support 5. Device I is placed below the ultraviolet lamp 8. The double-row pin header 4 of device I is connected to the other end of the double-row connector 6. The battery 7 provides overall power to a room temperature methane sensor.

[0018] Furthermore, a glass fiber epoxy resin composite board with dimensions of 12mm×22mm×1.6mm was selected as the substrate, and Au interdigitated electrodes 2 were prepared on its surface by chemical deposition. The Au interdigitated electrodes 2 have a finger width of 0.1mm, a finger spacing of 0.1mm, a finger pair number of 30, a sensing area of ​​10mm×11mm, and an electrode thickness of 0.02μm. Furthermore, an Ag-doped NH₂-C₃N₄ / CoAl-LDO nanosensor material layer was prepared. 0.5 mg of the Ag-doped NH₂-C₃N₄ / CoAl-LDO nanosensor material was ultrasonically dispersed in 5 times its volume of ethanol solution to prepare a suspension. This suspension was then uniformly coated onto the sensing area of ​​the Au interdigital electrode 2 and dried at 70°C for 3 hours to complete the modification of the sensing material. The XRD pattern of this material is attached. Figure 2 Corresponding to the standard card, SEM images (attached) Figure 3 This reveals its three-dimensional hierarchical layered structure, which provides ample gas adsorption channels and active sites; Furthermore, a double-row pin header 4 with a pin length of 6mm is selected and soldered to the lead-out end of the Au interdigital electrode 2 to complete the assembly of device I.

[0019] Furthermore, a double-layer copper-clad laminate with dimensions of 3cm×9cm×1.6mm was selected, and the upper and lower layers were connected by hexagonal copper pillars to form a cuboid cavity 5 (with dimensions of 3cm×9cm×3cm). The components of the data processing module were welded into the cavity to complete the assembly of device II.

[0020] Furthermore, device I is inserted into the lower interface of device II cavity, so that the double row of pins 4 and double row of females 6 are connected; the battery 7 in the data processing module is a 3.7V lithium battery, the resistance acquisition chip 9 is an ADS1115, the Bluetooth module 10 is a BLE5.0 module, and the ultraviolet lamp 8 is welded to the cavity directly above the sensing material 3 to ensure that the ultraviolet light uniformly illuminates the sensing area; the sensing area of ​​the sensor is open on all sides without obstruction, ensuring that methane gas can freely diffuse to the surface of Ag-doped NH2-C3N4 / CoAl-LDO nano-nano sensing material 3.

[0021] The performance test results of the room temperature methane sensor described in this embodiment are as follows: Table 1 shows a performance comparison between the Ag-doped NH2-C3N4 / CoAl-LDO nanosensor layer prepared in this embodiment and existing sensing materials: Table 1

[0022] The Ag-doped NH2-C3N4 / CoAl-LDO nanosensing material layer described in this embodiment effectively overcomes the performance defects of existing sensitive materials through the structural innovation of "layered NH2-C3N4 / CoAl-LDO composite + Ag noble metal doping". Its beneficial effects are as follows: 1. Room temperature stable sensing significantly reduces device energy consumption and safety risks. Compared with the dependence of existing SnO2-based (such as SnO2-rGO-PdPt requiring 150℃, SnO2-PdPt requiring 200℃) and ZnO-based (such as rGO / ZnO requiring 350℃) sensitive materials on high temperature driving, the material of this application can stably achieve the response of the target gas at room temperature (RT) without the need for an additional heating module. This avoids the problems of increased device energy consumption and complex heat dissipation design caused by high temperature, and also eliminates the overheating safety hazards in flammable and explosive gas detection scenarios, greatly improving the portability and application adaptability of the device.

[0023] 2. Breakthrough in Recovery Speed ​​to Overcome Room Temperature Sensing Bottlenecks and Adapt to Real-Time Monitoring Needs: Existing room temperature sensitive materials generally suffer from slow recovery speeds. For example, ZnO nanosheets (UV) take 480 seconds to recover at 1000 ppm target gas, and Ag / graphene still takes more than 22 minutes at a high concentration of 16000 ppm. In contrast, the material in this application takes only 36 seconds to recover at 500 ppm target gas and only 38 seconds at 1000 ppm target gas, which is more than 10 times faster than existing room temperature materials. It can achieve a rapid cycle of "gas adsorption-desorption" and is suitable for scenarios with high real-time response requirements, such as industrial leak early warning and indoor air quality monitoring.

[0024] 3. Superior response performance in the low to medium concentration range, matching practical application scenarios. Existing room temperature sensitive materials (such as Ag / graphene) can only achieve a response value of 2.4% at extremely high concentrations of 16,000 ppm (1.6%). However, the material of this application can achieve a response value of 13.7% in the low to medium concentration range (500 ppm) commonly found in actual environments, and the response value is further improved to 15.9% at 1,000 ppm. Within the typical actual concentration range of the target gas, the response sensitivity is significantly better than that of existing room temperature sensitive materials, and the detection accuracy can better meet the needs of practical applications.

[0025] 4. Significantly improved performance balance, with commercial application value. Existing sensitive materials suffer from performance contradictions such as "high response at high temperature but high energy consumption" and "low response at room temperature and slow speed" (e.g., SnO2-rGO-PdPt has a high response value at high temperature but a recovery time of up to 330s, and ZnO nanosheets work at room temperature but have extremely slow response / recovery speed). However, the material in this application achieves a performance balance of "room temperature operation, medium and low concentration response, and rapid recovery" through structural innovation, effectively filling the gap in the field of "low energy consumption-high performance" sensing materials and possessing broader commercial application prospects.

[0026] As attached Figure 4 As shown, within a methane concentration range of 500 ppm to 2000 ppm, the sensor exhibits a significant response, and the response value steadily increases with increasing concentration; (See attached image) Figure 5 Repeatability test results show that the sensor can continuously detect in a 2000ppm methane environment for 5 times with a response value fluctuation of less than 5%, demonstrating good stability; (Attached) Figure 6 The linear fitting curve shows that the correlation coefficient R 2 =0.92899, showing good linearity, with a detection limit of 500ppm, meeting the requirements for early warning of low-concentration methane leaks.

[0027] Example 2: A methane sensor for room temperature detection includes a glass fiber epoxy resin composite substrate 1, an Au interdigitated electrode 2, an Ag-doped NH2-C3N4 / CoAl-LDO nanosensing material layer 3, a double row of pins 4, a support 5, a double row of sockets 6, a battery 7, an ultraviolet lamp 8, a resistance acquisition chip 9, and a Bluetooth module 10. The device I consists of a glass fiber epoxy resin composite substrate 1, an Au interdigitated electrode 2, an Ag-doped NH2-C3N4 / CoAl-LDO nanosensing material layer 3, and a double-row pin header 4. The Au interdigitated electrode 2 is prepared on the surface of the glass fiber epoxy resin composite substrate 1 by chemical deposition. The Ag-doped NH2-C3N4 / CoAl-LDO nanosensing material layer 3 is uniformly coated on the sensing area of ​​the Au interdigitated electrode 2. The leads of the Au interdigitated electrode 2 are connected to the double-row pin header 4. The support 5, double-row connector 6, battery 7, ultraviolet lamp 8, resistance acquisition chip 9, and Bluetooth module 10 constitute device II. The double-row connector 6, resistance acquisition chip 9, Bluetooth module 10, and battery 7 are installed sequentially from left to right on the base plate of the support 5. One end of the double-row connector 6 is connected to the resistance acquisition chip 9, and the resistance acquisition chip 9 is connected to the Bluetooth module 10. The ultraviolet lamp 8 is installed on the top plate of the support 5. Device I is placed below the ultraviolet lamp 8. The double-row pin header 4 of device I is connected to the other end of the double-row connector 6. The battery 7 provides overall power to a room temperature methane sensor.

[0028] Furthermore, the Au interdigitated electrode 2 has a finger width of 0.05mm~0.5mm, a finger spacing of 0.05mm~0.5mm, a finger pair number of 30~50, a sensing area of ​​2mm×4mm~15mm×20mm, and an electrode thickness of 0.02μm~0.1μm.

[0029] Furthermore, the preparation method of the Ag-doped NH2-C3N4 / CoAl-LDO nanosensing material layer 3 is as follows: 0.5~50mg of Ag-doped NH2-C3N4 / CoAl-LDO nanosensing material is ultrasonically dispersed in 5 times the volume of ethanol solution to prepare a suspension. The suspension is uniformly coated on the sensing area of ​​the Au interdigital electrode 2 and dried at 60~70℃ for 2~3h to complete the modification of the sensing material.

[0030] Furthermore, the support 5 has a top plate and a bottom plate that are double-layered copper foil laminates, and the top plate and the bottom plate are connected by multiple hexagonal copper pillars to form a cuboid cavity shape.

[0031] Furthermore, the ultraviolet lamp 8 vertically irradiates the Ag-doped NH2-C3N4 / CoAl-LDO nanosensor material layer 3.

[0032] Furthermore, the preparation method of the Ag-doped NH2-C3N4 / CoAl-LDO nanosensor material includes the following steps: Step 1. Preparation of graphitic carbon nitride C3N4: Take a certain mass of melamine and spread it evenly in a porcelain boat; put the porcelain boat into a muffle furnace, set the heating rate to 5~10℃ / min and heat to 500℃, and calcine at a constant temperature of 500℃ in air for 4 hours; after the muffle furnace cools naturally to room temperature, take out the calcined product and grind it thoroughly into a fine powder with a mortar and pestle to obtain graphitic carbon nitride C3N4; Step 2. Amine-modified carbon nitride (NH) 2-Preparation of C3N4: Measure 30 mL of ammonia water and 90 mL of anhydrous ethanol into a beaker and stir evenly to prepare a mixed solvent; weigh 1 g of C3N4 powder obtained in step 1 and add it to the mixed solvent, sonicate until the powder is completely dispersed, transfer the dispersion to a three-necked flask, place it in a 70℃ constant temperature oil bath, and react at a constant temperature for 10 hours; after the reaction is completed, cool to room temperature and perform vacuum filtration; place the filter cake in a vacuum oven and dry it at 60℃ for 24 hours, grind it after drying to obtain NH2-C3N4 powder for later use; Step 3. Preparation of CoAl-LDHs: Weigh 0.8 mmol of cobalt nitrate hexahydrate, 0.4 mmol of aluminum nitrate nonahydrate, 4 mmol of ammonium fluoride, and 28 mmol of urea, and add them sequentially to a beaker containing 35 mL of deionized water. Stir magnetically for 1 hour until all solid reagents are completely dissolved, forming a clear and transparent precursor solution. Transfer the precursor solution to a hydrothermal reactor lined with polytetrafluoroethylene, seal it, and place it in a forced-air drying oven. Heat at 90°C for 6 hours. After the reaction is complete, allow the reactor to cool naturally to room temperature, open the reactor, and perform vacuum filtration. Place the filter cake in a vacuum oven and dry at 60°C for 24 hours to obtain CoAl-LDHs powder for later use. Step 4. Preparation of CoAl-LDO: Weigh the CoAl-LDHs powder obtained in Step 3 and spread it evenly in a porcelain boat; place the porcelain boat in a muffle furnace and calcine at a constant temperature of 500℃ for 4 hours; after the muffle furnace cools naturally to room temperature, take out the product, grind it evenly to obtain CoAl-LDO powder, and collect it for later use. Step 5. Preparation of NH2-C3N4 / CoAl-LDO composite material: Measure 50 mL of deionized water into a beaker, add 0.5 g of NH2-C3N4 powder obtained in step 2 and 1 g of CoAl-LDO powder obtained in step 4, and then add 0.015 g of polyvinylpyrrolidone; sonicate until the powder is completely dispersed, and then magnetically stir for 4 hours to obtain a mixture; transfer the mixture to a centrifuge tube and centrifuge at 8000 r / min; collect the solid product after centrifugation, put it in a vacuum oven, dry at 60℃ for 24 hours, grind it to obtain NH2-C3N4 / CoAl-LDO composite material for later use; Step 6. Preparation of Ag-doped NH2-C3N4 / CoAl-LDO composite material: Measure 50 mL of deionized water into a beaker, add 1 g of the NH2-C3N4 / CoAl-LDO composite material obtained in step 5, and ultrasonically disperse until a uniform suspension is formed; add 2.5 wt% silver nitrate solution and ascorbic acid at 3 times the mass of silver nitrate to the suspension in sequence; add KOH solution dropwise to adjust the pH value of the system to 8-9, and then transfer to a water bath and react at 40℃ for 12 hours; after the reaction is completed, centrifuge at 8000 r / min to separate and collect the solid product; put the product into a vacuum oven and dry at 60℃ for 24 hours, and grind to obtain the Ag-doped NH2-C3N4 / CoAl-LDO composite material.

[0033] Furthermore, the Bluetooth module 10 is connected to an external terminal.

[0034] Example 3: The retrieval method for a room temperature methane sensor according to Example 2 includes the following steps: S1. Connect the battery power supply, turn on the ultraviolet lamp for preheating for 5 minutes, and use the resistance acquisition chip to collect the baseline resistance R of the Ag-doped NH2-C3N4 / CoAl-LDO composite material layer in air. a ; S2. The room-temperature methane sensor is placed in a methane-containing detection environment. Methane gas diffuses to and adsorbs onto the surface of the Ag-doped NH2-C3N4 / CoAl-LDO nanosensor material layer. Under ultraviolet light excitation, methane molecules are activated, causing a change in the resistance of the Ag-doped NH2-C3N4 / CoAl-LDO nanosensor material layer. The resistance acquisition chip captures this changed resistance R in real time. g ; S3. The response value is calculated as follows: According to the linear fitting equation x is the concentration of methane in the gas to be tested (ppm), and y is the response value. The methane concentration x is deduced from the detected response value y and transmitted to an external terminal via Bluetooth module to achieve quantitative detection. S4. After the detection is completed, the ultraviolet lamp continues to irradiate to promote the desorption of residual gas on the surface of the Ag-doped NH2-C3N4 / CoAl-LDO nanosensor material layer, and the sensor returns to the baseline state for the next detection.

[0035] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0036] Although this application has been described above with reference to specific embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of this application. In particular, as long as there is no structural conflict, the features in the specific embodiments disclosed in this application can be combined with each other in any way. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, this application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A methane sensor for room temperature detection, characterized in that, The components include a glass fiber epoxy resin composite substrate (1), an Au interdigitated electrode (2), an Ag-doped NH2-C3N4 / CoAl-LDO nanosensing material layer (3), a double row of pin headers (4), a support (5), a double row of female headers (6), a battery (7), an ultraviolet lamp (8), a resistance acquisition chip (9), and a Bluetooth module (10). The glass fiber epoxy resin composite substrate (1), Au interdigitated electrode (2), Ag-doped NH2-C3N4 / CoAl-LDO nanosensing material layer (3), and double-row pin header (4) constitute device I; Au interdigitated electrode (2) is prepared on the surface of glass fiber epoxy resin composite substrate (1) by chemical deposition, and Ag-doped NH2-C3N4 / CoAl-LDO nanosensing material layer (3) is uniformly coated on the sensing area of ​​Au interdigitated electrode (2), and the lead-out end of Au interdigitated electrode (2) is connected to double-row pin header (4); The preparation method of the Ag-doped NH2-C3N4 / CoAl-LDO nanosensing material layer (3) is as follows: 0.5~50mg of Ag-doped NH2-C3N4 / CoAl-LDO nanosensing material is ultrasonically dispersed in 5 times the volume of ethanol solution to prepare a suspension. The suspension is uniformly coated on the sensing area of ​​the Au interdigitated electrode (2). After drying at 60~70℃ for 2~3h, the modification of the sensing material is completed. The support (5), double-row connector (6), battery (7), ultraviolet lamp (8), resistance acquisition chip (9), and Bluetooth module (10) constitute device II; the double-row connector (6), resistance acquisition chip (9), Bluetooth module (10), and battery (7) are installed sequentially from left to right on the base plate of the support (5), one end of the double-row connector (6) is connected to the resistance acquisition chip (9), and the resistance acquisition chip (9) is connected to the Bluetooth module (10); the ultraviolet lamp (8) is installed on the top plate of the support (5); device I is placed below the ultraviolet lamp (8), the double-row pins (4) of device I are connected to the other end of the double-row connector (6), and the battery (7) provides overall power for a room temperature methane sensor.

2. The methane sensor for room temperature detection according to claim 1, characterized in that, The Au interdigitated electrode (2) has a finger width of 0.05mm~0.5mm, a finger spacing of 0.05mm~0.5mm, a finger pair number of 30~50, a sensing area of ​​2mm×4mm~15mm×20mm, and an electrode thickness of 0.02μm~0.1μm.

3. A room temperature methane sensor according to claim 2, characterized in that, The top and bottom plates of the support (5) are double-layer copper foil laminates, and the top and bottom plates are connected by multiple hexagonal copper pillars to form a cuboid cavity shape.

4. A room temperature methane sensor according to claim 3, characterized in that, The ultraviolet lamp (8) vertically irradiates the Ag-doped NH2-C3N4 / CoAl-LDO nanosensor material layer (3).

5. A room temperature methane sensor according to claim 4, characterized in that, The preparation method of the Ag-doped NH2-C3N4 / CoAl-LDO nanosensor material includes the following steps: Step 1. Preparation of graphitic carbon nitride C3N4: Take a certain mass of melamine and spread it evenly in a porcelain boat; put the porcelain boat into a muffle furnace, set the heating rate to 5~10℃ / min and heat to 500℃, and calcine at a constant temperature of 500℃ in air for 4 hours; after the muffle furnace cools naturally to room temperature, take out the calcined product and grind it thoroughly into a fine powder with a mortar and pestle to obtain graphitic carbon nitride C3N4; Step 2. Preparation of amino-modified carbon nitride NH2-C3N4: Measure 30 mL of ammonia water and 90 mL of anhydrous ethanol into a beaker, stir evenly to prepare a mixed solvent; weigh 1 g of C3N4 powder obtained in step 1 and add it to the mixed solvent, sonicate until the powder is completely dispersed, transfer the dispersion to a three-necked flask, place it in a 70℃ constant temperature oil bath, and react at a constant temperature for 10-12 hours; after the reaction is completed, cool to room temperature and perform vacuum filtration; place the filter cake in a vacuum oven and dry at 60℃ for 24 hours, grind after drying to obtain NH2-C3N4 powder for later use; Step 3. Preparation of CoAl-LDHs: Weigh 0.8 mmol of cobalt nitrate hexahydrate, 0.4 mmol of aluminum nitrate nonahydrate, 4 mmol of ammonium fluoride, and 28 mmol of urea, and add them sequentially to a beaker containing 35 mL of deionized water. Stir magnetically for 1 hour until all solid reagents are completely dissolved, forming a clear and transparent precursor solution. Transfer the precursor solution to a hydrothermal reactor lined with polytetrafluoroethylene, seal it, and place it in a forced-air drying oven. Heat at 90°C for 6-8 hours. After the reaction is complete, allow the reactor to cool naturally to room temperature, open the reactor, and perform vacuum filtration. Place the filter cake in a vacuum oven and dry at 60°C for 24 hours to obtain CoAl-LDHs powder for later use. Step 4. Preparation of CoAl-LDO: Weigh the CoAl-LDHs powder obtained in Step 3 and spread it evenly in a porcelain boat; place the porcelain boat in a muffle furnace and calcine at a constant temperature of 500℃ for 4 hours; after the muffle furnace cools naturally to room temperature, take out the product, grind it evenly to obtain CoAl-LDO powder, and collect it for later use. Step 5. Preparation of NH2-C3N4 / CoAl-LDO composite material: Measure 50 mL of deionized water into a beaker, add 0.5 g of NH2-C3N4 powder obtained in step 2 and 1 g of CoAl-LDO powder obtained in step 4, and then add 0.015 g of polyvinylpyrrolidone; sonicate until the powder is completely dispersed, and then magnetically stir for 4 hours to obtain a mixture; transfer the mixture to a centrifuge tube and centrifuge at 8000 r / min. The solid product after centrifugation was collected, placed in a vacuum oven, dried at 60°C for 24 hours, and then ground to obtain the NH2-C3N4 / CoAl-LDO composite material for later use. Step 6. Preparation of Ag-doped NH2-C3N4 / CoAl-LDO composite material: Measure 50 mL of deionized water into a beaker, add 1 g of the NH2-C3N4 / CoAl-LDO composite material obtained in step 5, and ultrasonically disperse until a uniform suspension is formed; add 0.05~2.5 wt% silver nitrate solution and ascorbic acid at 3 times the mass of silver nitrate to the suspension in sequence; add KOH solution dropwise to adjust the pH value of the system to 8~9, and then transfer to a water bath and react at 40℃ for 12~16 hours; after the reaction is completed, centrifuge at 8000 r / min to separate and collect the solid product; put the product into a vacuum oven and dry at 40℃ for 24 hours, and grind to obtain the Ag-doped NH2-C3N4 / CoAl-LDO composite material.

6. A methane sensor for room temperature detection according to claim 5, characterized in that, The Bluetooth module (10) is connected to an external terminal.

7. A method for detecting methane using a room temperature sensor according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Connect the battery power supply, turn on the ultraviolet lamp for preheating for 5 minutes, and use the resistance acquisition chip to collect the baseline resistance R of the Ag-doped NH2-C3N4 / CoAl-LDO composite material layer in air. a ; S2. The room-temperature methane sensor is placed in a methane-containing detection environment. Methane gas diffuses to and adsorbs onto the surface of the Ag-doped NH2-C3N4 / CoAl-LDO nanomaterial layer. Under ultraviolet irradiation, the methane molecules are activated, causing a change in the resistance of the Ag-doped NH2-C3N4 / CoAl-LDO nanomaterial layer. The resistance acquisition chip captures this change in resistance R in real time. g ; S3. The response value is calculated as y = (R g -R a ) / R a According to the linear fitting equation y=0.15667+7.87313×10⁻ 6 x, where x is the concentration of methane in the gas to be tested (ppm), and the concentration range of x is 500ppm~2000ppm; y is the response value. The methane concentration x is deduced from the detected response value y and transmitted to an external terminal via Bluetooth module to achieve quantitative detection. S4. After the detection is completed, the ultraviolet lamp continues to irradiate to promote the desorption of residual gas on the surface of the Ag-doped NH2-C3N4 / CoAl-LDO nanosensor material layer, and the sensor returns to the baseline state for the next detection.

Images