Methane gas sensitive material, preparation method and application thereof

Abstract

The application relates to the technical field of gas sensing, and discloses a methane gas-sensitive material and a preparation method and application thereof, wherein the methane gas-sensitive material comprises Ti2CTx and SnO2 nanomaterials loaded on the Ti2CTx; the content of the SnO2 nanomaterials is 5-35 wt% based on the total weight of the methane gas-sensitive material. X The application adopts Ti2CT X as a modifier to improve the sensing performance (high working temperature and long response time) of SnO2, and the prepared SnO2@Ti2CT X The methane gas-sensitive material has a series of unique physical and chemical properties, such as high conductivity and good stability, Ti2CT X can synergistically accelerate the response speed of methane and improve the response intensity; based on the SnO2@Ti2CT X The sensor prepared from the methane gas-sensitive material has good linear response to methane gas in the range of 0-500 ppm under room temperature conditions; in addition, the sensor has good reproducibility, an extremely low detection limit (1 ppm) and good sensitivity.

Description

Technical Field

[0001] This invention relates to the field of gas sensing technology, specifically to a methane gas-sensitive material, its preparation method, and its application. Background Technology

[0002] Methane is a major component of coal mine gas, natural gas, shale gas, and biogas. However, due to its colorless, odorless, flammable, and explosive properties, it poses a potential threat during use. In industrial production, gas hazards, especially methane explosions, are a major factor limiting safe production in coal mines. It is noteworthy that methane concentrations in the air ranging from 4.9% to 15% can lead to coal mine gas explosions and fires, causing serious casualties and property damage.

[0003] Therefore, achieving quantitative detection of methane using reliable gas sensors is crucial. Traditional chemiluminescence (CET) gas sensors, typically fabricated from low-cost, small-sized metal-oxide-semiconductor (MOS) materials, play a vital role in methane detection. To date, various MOS materials capable of detecting methane have been reported, such as tin oxide (SnO2), zinc oxide (ZnO), indium oxide (In2O3), and nickel oxide (NiO). Among all these MOS materials, SnO2 was the first to be discovered for methane detection and exhibits the best response to methane, making it one of the most promising gas sensing materials. Currently, most commercially available MOS-type methane gas sensors are developed using tin oxide as the base material. However, pure tin oxide sensors still suffer from drawbacks, such as low sensitivity, poor stability, and high operating temperature. Addressing these issues is a key focus of current methane gas sensor research. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of low sensitivity, poor stability and high operating temperature of pure tin oxide sensors in the prior art, and to provide a methane gas-sensitive material, its preparation method and application.

[0005] To achieve the above objectives, the present invention provides a methane gas-sensitive material, the methane gas-sensitive material comprising Ti2CTx and a substrate loaded on the Ti2CTx. X SnO2 nanomaterials on;

[0006] Based on the total weight of the methane gas-sensitive material, the content of the SnO2 nanomaterial is 5-35 wt%.

[0007] Preferably, the specific surface area of ​​the methane gas-sensitive material is 100–600 m². 2 / g.

[0008] Preferably, the SnO2 nanomaterial is selected from one or more of SnO2 nanoparticles, SnO2 nanosheets, and SnO2 nanospheres;

[0009] Preferably, the SnO2 nanoparticles have a size of 100–500 nm;

[0010] Preferably, the thickness of the SnO2 nanosheets is 10–200 nm;

[0011] Preferably, the SnO2 nanospheres have a diameter of 600–1500 nm.

[0012] A second aspect of the present invention provides a method for preparing the methane gas-sensitive material as described above, the method comprising:

[0013] (1) SnO2 nanomaterials and Ti2CT X Mix with the first solvent;

[0014] (2) The material obtained in step (1) is subjected to solid-liquid separation, and then the obtained solid material is freeze-dried.

[0015] Preferably, in step (1), the Ti2CT X The weight ratio of SnO2 nanomaterials used is 1:0.1 to 0.5;

[0016] Preferably, in step (1), the Ti2CT X The weight ratio of the amount of solvent used to the first solvent is 1:100 to 400;

[0017] Preferably, in step (1), the mixing conditions include: a temperature of 0–100°C and a time of 2–36 h;

[0018] Preferably, in step (1), the first solvent is selected from one or more of water, ethanol, methanol, chloroform and acetone;

[0019] Preferably, in step (2), the freeze-drying conditions include: a temperature of -70 to -40°C and a time of 2 to 36 hours.

[0020] Preferably, the method further includes preparing Ti2CT according to the following steps. X :

[0021] Ti₂AlC is mixed with a solution containing fluoride ions and hydrogen ions, and then the first reaction is carried out.

[0022] Preferably, the conditions for the first reaction include: a temperature of 10–70°C and a time of 10–48 h.

[0023] Preferably, the SnO2 nanomaterial is selected from one or more of SnO2 nanoparticles, SnO2 nanosheets, and SnO2 nanospheres.

[0024] Preferably, the SnO2 nanoparticles are prepared according to the following steps:

[0025] Oxalic acid dihydrate, stannous chloride dihydrate and water are mixed, then mixed with polyvinylpyrrolidone, and then the first hydrothermal reaction is carried out.

[0026] The obtained product was washed, separated from its solid state, dried, and then subjected to a first calcination.

[0027] Preferably, the weight ratio of oxalic acid dihydrate, stannous chloride dihydrate, and polyvinylpyrrolidone is 1:0.05-0.2:0.2-0.8.

[0028] Preferably, the conditions for the first hydrothermal reaction include: a temperature of 100–200°C and a time of 5–30 h;

[0029] Preferably, the conditions for the first roasting include: a temperature of 400–600°C and a time of 5–20 h.

[0030] A third aspect of the present invention provides a methane gas-sensitive material prepared by the method described above.

[0031] A fourth aspect of the present invention provides a methane sensor comprising the methane gas-sensitive material as described above.

[0032] The fifth aspect of the present invention provides a method for preparing a methane sensor as described above, the method comprising: mixing and grinding a methane gas-sensitive material and an organic solvent, and then coating the mixture onto the surface of an electrode to form a sensing film;

[0033] Preferably, the thickness of the sensing film is 200–5000 nm.

[0034] The sixth aspect of the present invention provides an application of the methane gas-sensitive material or the methane sensor described above in methane detection.

[0035] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0036] 1. This invention uses Ti2CT X SnO2 was used as a modifier to improve the sensing performance of SnO2 (high operating temperature and long response time). The prepared SnO2@Ti2CT X Methane gas-sensitive materials possess a series of unique physical and chemical properties, such as high conductivity and good stability. (Ti2CT) X It can synergistically accelerate the response rate of methane and increase the response intensity with SnO2.

[0037] 2. The SnO2@Ti2CT provided by this invention X Methane gas-sensitive material, SnO2 supported on Ti2CT X The surface and interlayer of the sheets form a hamburger-like structure, which can accelerate the transmission of electrical signals, thereby greatly improving response and recovery capabilities.

[0038] 3. The SnO2@Ti2CT provided by this invention X Methane gas-sensitive materials directly address the problem of methane leakage monitoring and detection in the atmospheric environment. They can detect leaked methane in the environment with high sensitivity and selectivity at room temperature, reducing the hazards caused by methane leaks and thus ensuring the safety of personnel, the environment, and equipment.

[0039] 4. This invention employs an in-situ self-assembly method to modify Ti2CT with SnO2. X SnO2@Ti2CT can be prepared in one step. X Methane gas-sensitive materials have a simple preparation process, are easy to industrialize, and are conducive to the large-scale production and application of sensors.

[0040] 5. Based on the SnO2@Ti2CT described in this invention X The sensor made from methane gas-sensitive material exhibits good linear response to methane gas in the range of 0–500 ppm at room temperature. In addition, the sensor has good reproducibility, an extremely low detection limit (1 ppm), and good sensitivity. Attached Figure Description

[0041] Figure 1 The Ti2CT obtained in Example 1 of this invention X Scanning electron microscope image;

[0042] Figure 2 This is a scanning electron microscope image of the SnO2 nanoparticles prepared in Example 1 of this invention;

[0043] Figure 3 The SnO2@Ti2CT prepared in Example 1 of this invention X Scanning electron microscope image of a methane gas-sensitive material;

[0044] Figure 4 This is the SnO2@Ti2CT prepared in Example 3 of the present invention. X Scanning electron microscope image of a methane gas-sensitive material;

[0045] Figure 5 This is a response curve of a methane sensor made from the methane gas-sensitive material prepared in Embodiment 1 and Comparative Examples 1-2 of the present invention to different concentrations of methane. Detailed Implementation

[0046] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0047] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0048] Most MOS-type methane gas sensors currently on the market are developed using tin oxide as the basic material. However, pure tin oxide sensors still have some drawbacks, such as low sensitivity, poor stability, and high operating temperature. How to solve these problems is the focus of current research on methane gas sensors.

[0049] This invention has discovered through research that Ti2CT X The combination with SnO2 effectively reduces resistance, thus achieving room temperature detection. SnO2@Ti2CT X The formation of the complex provides abundant active adsorption sites for methane, improving sensing performance. Therefore, this invention provides a methane gas-sensitive material, its preparation method, and its application. This methane gas-sensitive material comprises Ti2CTx and a substrate loaded on the Ti2CTx substrate. X The SnO2 nanomaterials are used; based on the total weight of the methane gas-sensitive material, the content of the SnO2 nanomaterials is 5-35 wt%.

[0050] The invention described based on Ti2CT X Methane gas-sensitive materials based on SnO2 exhibit characteristics such as low operating temperature, high sensitivity, good stability, and good selectivity, for example: SnO2@Ti2CT X The methane gas-sensitive material can achieve an ultrafast response to 1 ppm methane within 10 seconds at room temperature, with a detection range of 1 ppm to 500 ppm.

[0051] In this invention, monodisperse SnO2 nanomaterials are uniformly modified on Ti2CT. X The above serves as an active site for the rapid adsorption and dissociation of methane.

[0052] In this invention, Ti2CT X The microstructure is accordion-like sheets, with each nanosheet having a thickness of 10–150 nm. This facilitates the embedding of SnO2 nanomaterials into Ti2CT. XWithin the hierarchical structure, this avoids the aggregation of SnO2 nanomaterials and inhibits Ti2CT. X The collapse of the structure is beneficial to the improvement of stability, charge migration, transport and sensing performance, and can also provide an ideal diffusion channel for methane.

[0053] This invention improves the stability and sensitivity to methane gas by controlling the loading of SnO2 nanomaterials in the methane gas-sensitive material. In specific embodiments, based on the total weight of the methane gas-sensitive material, the content of the SnO2 nanomaterials can be 5 wt%, 10 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 23 wt%, 24 wt%, 25 wt%, 30 wt%, or 35 wt%.

[0054] In a preferred embodiment, the SnO2 nanomaterial content is 10-30 wt%, based on the total weight of the methane gas-sensitive material.

[0055] In a preferred embodiment, to improve the adsorption capacity of the methane gas-sensitive material for methane gas, the specific surface area of ​​the methane gas-sensitive material is 100–600 m². 2 / g.

[0056] In a preferred embodiment, the SnO2 nanomaterial is selected from one or more of SnO2 nanoparticles, SnO2 nanosheets, and SnO2 microspheres. By selecting the above-mentioned types of SnO2 nanomaterials, the SnO2 nanomaterials can be better embedded in Ti2CT. X Internally, improve Ti2CT X This addresses the issue of collapse, thereby improving its stability.

[0057] In a preferred embodiment, the size (diameter) of the SnO2 nanoparticles is 100–500 nm.

[0058] In a preferred embodiment, the thickness of the SnO2 nanosheet is 10–200 nm.

[0059] In a preferred embodiment, the diameter of the SnO2 nanospheres is 600–1500 nm.

[0060] The SnO2 and Ti2CT based invention X The methane gas-sensitive material exhibits good conductivity and stability, along with excellent sensitivity and response to methane. This is primarily due to the large specific surface area of ​​SnO2 nanomaterials, which, acting as active sites, can rapidly adsorb and dissociate methane. Furthermore, based on SnO2 and Ti2CT... XThe methane gas-sensitive material exhibits distinct layers, providing an ideal channel for methane diffusion; furthermore, SnO2 nanomaterials embedded with Ti2CT... X Within the hierarchical structure, this avoids both the aggregation of SnO2 nanomaterials and the inhibition of Ti2CT. X The collapse of the structure is beneficial to the improvement of stability, charge migration, transmission and sensing performance.

[0061] The present invention also provides a method for preparing the methane gas-sensitive material as described above, the method comprising:

[0062] (1) SnO2 nanomaterials and Ti2CT X Mix with the first solvent;

[0063] (2) The material obtained in step (1) is subjected to solid-liquid separation, and then the obtained solid material is freeze-dried to obtain SnO2@Ti2CT. X Methane gas-sensitive materials.

[0064] This invention prepares SnO2@Ti2CT via an in-situ method. X A methane gas-sensitive material, this composite material has a higher specific surface area than the single component, which provides more active sites for the adsorption of methane molecules. It exhibits fast response speed, high repeatability, and high selectivity to methane at room temperature, thus demonstrating excellent sensing performance as a methane gas-sensitive material. Furthermore, the methane response performance of this material is significantly better than that of the original SnO2, indicating that Ti2CT… X The addition of [a specific ingredient] plays a key role in improving the sensing performance of SnO2.

[0065] For the Ti2CT X Regarding the relationship between the amount of SnO2 nanomaterials used and the quantity, this invention does not impose any limitations, as long as the loading of SnO2 nanomaterials in the prepared methane gas-sensitive material is adjusted to be 5-35 wt%. To improve the performance of SnO2 and Ti2CT-based materials... X The stability and sensitivity to methane gas of the methane gas-sensitive material are improved. In the preferred embodiment, in step (1), Ti2CT... X The weight ratio of Ti2CTx to SnO2 nanomaterials is 1:0.1 to 0.5; specifically, the weight ratio of Ti2CTx to SnO2 nanomaterials can be 1:0.1, 1:0.2, 1:0.3, 1:0.4 or 1:0.5.

[0066] To better disperse SnO2 nanomaterials, in a preferred embodiment, in step (1), Ti2CT XThe weight ratio of Ti2CTx to the first solvent is 1:100 to 400; specifically, the weight ratio of Ti2CTx to the first solvent can be 1:100, 1:150, 1:200, 1:250, 1:300, 1:350 or 1:400.

[0067] In this invention, there are no special requirements for the first solvent, and conventional solvents in the art can be used. In a preferred embodiment, the first solvent is selected from one or more of water, ethanol, methanol, chloroform, and acetone.

[0068] In order to further improve the stability of the methane gas-sensitive material and its sensitivity to methane gas, in a preferred embodiment, the mixing conditions in step (1) include: a temperature of 0 to 100°C and a time of 2 to 36 hours; specifically, the temperature can be 20°C, 40°C, 60°C, 80°C or 100°C, and the time can be 6 hours, 12 hours, 18 hours, 24 hours, 30 hours or 36 hours.

[0069] In a preferred embodiment, step (1) specifically includes: applying Ti2CT... X After mixing with the first solvent, the mixture is ultrasonically treated, then SnO2 nanomaterials are added and stirred under light-protected conditions, followed by reflux.

[0070] More preferably, the conditions for the ultrasonic treatment include: power of 500-700W, temperature of 20-30℃, and time of 20-60min.

[0071] More preferably, the stirring time under light-protected conditions is 2 to 4 hours.

[0072] More preferably, the reflux conditions include a temperature of 50–70°C and a time of 5–7 hours.

[0073] In a preferred embodiment, in step (2), solid-liquid separation is performed by centrifugation at a speed of 8000-10000 r / min.

[0074] In a preferred embodiment, in step (2), the freeze-drying conditions include: a temperature of -70 to -40°C and a time of 2 to 36 hours; specifically, the temperature can be -70°C, -65°C, -60°C, -55°C, -50°C, -45°C, or -40°C; and the time can be 6 hours, 12 hours, 18 hours, 24 hours, 30 hours, or 36 hours.

[0075] For the Ti2CT X The specific source of the Ti2CT is not limited in this invention; it can be purchased or prepared by the user. In a preferred embodiment, in step (1), the Ti2CT... XTo achieve self-preparation, specifically, the method also includes preparing Ti2CT according to the following steps. X :

[0076] The first reaction was carried out by mixing Ti3AlC2 with a solution containing fluoride ions and hydrogen ions.

[0077] In a preferred embodiment, the conditions for the first reaction include: a temperature of 10–70°C and a time of 5–50 h; specifically, the temperature can be 10°C, 20°C, 30°C, 35°C, 40°C, 50°C, 60°C, or 70°C; and the time can be 10 h, 12 h, 24 h, 36 h, or 50 h.

[0078] In a preferred embodiment, Ti2CT X The specific preparation process includes:

[0079] A1. After mixing Ti3AlC2 with a solution containing fluoride ions and hydrogen ions, a first reaction is carried out, followed by solid-liquid separation. The resulting solid product is washed, vacuum filtered, and the precipitate is collected.

[0080] A2. Dry the precipitate obtained in step A1;

[0081] A3. The intermediate material obtained after drying in step A2 is subjected to ultrasonic and solid-liquid separation treatment.

[0082] In the method described in this invention, the solid-liquid separation, washing, drying, and ultrasonication are all conventional methods in the art.

[0083] In a specific implementation, a polytetrafluoroethylene membrane with a pore size of 0.22 μm is used to perform vacuum filtration on the washed material.

[0084] In one specific implementation, the Ti2CT X The preparation is carried out according to the following steps: Ti3AlC2 is mixed with a solution containing fluoride ions and hydrogen ions and reacted, then solid-liquid separation and washing are performed until the pH value of the supernatant is 6. The washed material is vacuum filtered using a polytetrafluoroethylene membrane with a pore size of 0.22 μm, then dried in a vacuum drying oven, the dried material is dispersed in water and subjected to low-temperature ultrasonic treatment, and finally solid-liquid separation is performed.

[0085] In this invention, there are no special requirements regarding the specific type of solution containing fluoride and hydrogen ions, as long as the solution contains fluoride and hydrogen ions. Specifically, for example, it can be a mixed solution of hydrofluoric acid or an inorganic acid and a fluoride salt.

[0086] The present invention also does not require a specific amount of the solution containing fluoride ions and hydrogen ions, as long as the Al atoms in Ti2AlC can be removed.

[0087] Ti2CT prepared using the above-described preparation process X The microstructure is accordion-like sheets with a thickness of 10–150 nm, which is beneficial for the embedding of SnO2 nanomaterials into Ti2CT. X Within the hierarchical structure, this avoids the aggregation of SnO2 nanomaterials and inhibits Ti2CT. X The collapse of the structure is beneficial to the improvement of stability, charge migration, transport and sensing performance, and can also provide an ideal diffusion channel for methane.

[0088] In a preferred embodiment, in step (1), the SnO2 nanomaterial is selected from one or more of SnO2 nanoparticles, SnO2 nanosheets, and SnO2 nanospheres. Based on this, the SnO2 nanomaterial can be better embedded in Ti2CT. X Internally, improve Ti2CT X This addresses the issue of collapse, thereby improving its stability.

[0089] In a preferred embodiment, the SnO2 nanoparticles have a size (diameter) of 100–500 nm.

[0090] This invention does not limit the specific source of the SnO2 nanoparticles, as long as their size is 100-500 nm. In a preferred embodiment, the SnO2 nanoparticles are prepared according to the following steps: oxalic acid dihydrate, stannous chloride dihydrate, and water are mixed, then mixed with polyvinylpyrrolidone (PVP), followed by a first hydrothermal reaction; the resulting product is washed, subjected to solid-liquid separation, and the resulting solid product is dried, followed by a first calcination.

[0091] In a preferred embodiment, the weight ratio of oxalic acid dihydrate, stannous chloride dihydrate, and polyvinylpyrrolidone is 1:0.05-0.2:0.3-0.8.

[0092] In a preferred embodiment, the conditions for the first hydrothermal reaction include: a temperature of 100–200°C and a time of 5–30 h; specifically, the temperature can be 100°C, 120°C, 130°C, 150°C, 160°C, 180°C, or 200°C; and the time can be 5 h, 7 h, 10 h, 12 h, 15 h, 20 h, 25 h, or 30 h.

[0093] In a preferred embodiment, the conditions for the first roasting include: a temperature of 400–600°C and a time of 5–20 h; specifically, the temperature can be 400°C, 450°C, 500°C, 550°C, or 600°C; and the time can be 5 h, 7 h, 10 h, 12 h, 15 h, or 20 h.

[0094] In a specific embodiment, the preparation process of the SnO2 nanoparticles specifically includes: adding oxalic acid dihydrate and stannous chloride dihydrate to deionized water, stirring thoroughly, adding polyvinylpyrrolidone (PVP), stirring the solution thoroughly, transferring it to a 100mL polytetrafluoroethylene reactor for a first hydrothermal reaction, then washing with ethanol and water, followed by drying, and finally performing a first calcination.

[0095] In a preferred embodiment, the thickness of the SnO2 nanosheet is 10–200 nm.

[0096] This invention does not limit the specific source of the SnO2 nanosheets; they can be purchased or prepared in-house. When preparing in-house, they can be prepared using conventional methods for preparing SnO2 nanosheets in the art. In a preferred embodiment, the SnO2 nanosheets are prepared according to the following steps: dissolving tin dichloride dihydrate in deionized water, then mixing it with sodium hydroxide, subjecting the resulting mixture to a second hydrothermal reaction; washing and drying the resulting product, followed by a second calcination.

[0097] In a preferred embodiment, the weight ratio of tin dichloride dihydrate to sodium hydroxide is 1:0.4 to 0.8.

[0098] In a preferred embodiment, the conditions for the second hydrothermal reaction include: a temperature of 100–200°C and a time of 3–35 h; specifically, the temperature can be 100°C, 120°C, 130°C, 150°C, 160°C, 180°C, or 200°C; and the time can be 3 h, 4 h, 5 h, 7 h, 10 h, 15 h, 18 h, 20 h, 25 h, or 35 h.

[0099] More preferably, the temperature of the second hydrothermal reaction is 100–200°C, and the time is 3–10 hours.

[0100] In a preferred embodiment, the conditions for the second calcination include: a temperature of 400–600°C and a time of 5–30 h; specifically, the temperature can be 400°C, 450°C, 500°C, 550°C, or 600°C; and the time can be 5 h, 7 h, 8 h, 10 h, 12 h, 15 h, 20 h, 25 h, or 30 h.

[0101] In a preferred embodiment, the diameter of the SnO2 nanospheres is 600–1500 nm.

[0102] This invention does not limit the specific source of the SnO2 nanospheres; they can be purchased or prepared in-house. When preparing in-house, they can be prepared using conventional methods in the art. In a preferred embodiment, the SnO2 nanospheres are prepared according to the following steps: SnSO4 is mixed with water, then mixed with sodium benzenesulfonate, and the resulting mixture undergoes a third hydrothermal reaction; the resulting product is washed, dried, and then calcined.

[0103] In a preferred embodiment, the weight ratio of SnSO4 to sodium benzenesulfonate is 1:0.8 to 1.2.

[0104] In a preferred embodiment, the conditions for the third hydrothermal reaction include: a temperature of 100–180°C and a time of 5–30 h; specifically, the temperature can be 100°C, 120°C, 130°C, 140°C, 150°C, 160°C, or 180°C; and the time can be 5 h, 8 h, 10 h, 12 h, 15 h, 20 h, 25 h, or 30 h.

[0105] In a preferred embodiment, the conditions for the third calcination include: a temperature of 400–600°C and a time of 3–15 hours; specifically, the temperature can be 400°C, 450°C, 500°C, 550°C, or 600°C, and the time can be 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, or 15 hours.

[0106] The method provided by this invention uses in-situ synthesis technology to grow SnO2 in situ on Ti2CT. X SnO2@Ti2CT was prepared by utilizing the interaction between MXene and SnO2 in the material sheets. X Gas-sensitive materials. Ti2CT X The high conductivity of SnO2 effectively reduces the resistance of gas-sensitive materials, thereby lowering the operating temperature and enabling room-temperature detection. The supporting effect of SnO2 crystal particles can improve the poor stability caused by MXene sheet collapse, while also inhibiting SnO2 aggregation. Layered SnO2@Ti2CT X The construction of the MXene structure creates a rich interface structure, which can significantly change the charge transport rate, surface adsorption energy and active site density, thereby improving the response speed and detection sensitivity.

[0107] The present invention also provides a methane gas-sensitive material prepared by the above method.

[0108] The present invention also provides a methane sensor comprising the methane gas-sensitive material as described above.

[0109] Because the methane gas-sensitive material described above exhibits fast response speed, high sensitivity, repeatability, and selectivity to methane at room temperature, along with good stability, the methane sensor prepared based on this invention has high sensitivity to methane. It can directly address the problem of methane leakage monitoring and detection in the atmospheric environment, enabling highly selective and rapid detection of leaked methane at room temperature, reducing the hazards caused by methane leaks, and thus ensuring the safety of personnel, the environment, and equipment.

[0110] The present invention also proposes a method for preparing the above-mentioned methane sensor, the method comprising: mixing and grinding a methane gas-sensitive material and an organic solvent, and then coating it on the surface of an electrode to form a sensing film.

[0111] In a preferred embodiment, in order to improve the sensitivity of the methane sensor, the weight ratio of the methane gas-sensitive material to the organic solvent is 1:1 to 10; specifically, the weight ratio of the methane gas-sensitive material to the organic solvent can be 1:1, 1:2, 1:4, 1:6, 1:8 or 1:10.

[0112] In this invention, there are no special requirements for the organic solvent; any commonly used solvent in the art is acceptable, such as terpineol.

[0113] In a preferred embodiment, to further improve the sensitivity of the methane sensor, the thickness of the sensing film is 200–5000 nm, more preferably 200–600 nm.

[0114] The present invention also provides the application of the methane gas-sensitive material or methane sensor described above in methane detection.

[0115] In a specific implementation, when methane gas detection is performed, the aforementioned methane sensor or methane gas-sensitive material is brought into contact with a mixed gas containing methane.

[0116] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited thereto. Unless otherwise specified, the experimental methods in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available products.

[0117] In the following examples and comparative examples, an energy dispersive spectroscopy (EDS) semi-quantitative analysis of methane gas-sensitive materials was performed using an energy dispersive spectroscopy (EDS) instrument to calculate the loading of SnO2 nanomaterials.

[0118] In the following examples and comparative examples, the morphology of the prepared products was characterized using a scanning electron microscope (SEM), wherein the SEM was a Hitachi SU3800.

[0119] Example 1

[0120] Preparation of Ti2CT X (S1):

[0121] A1: Add 2g of Ti2AlC to 80ml of 32% hydrofluoric acid and stir at 30℃ for 36h. Then centrifuge and wash with deionized water until the pH of the supernatant is 6. Then vacuum filter the washed material with a polytetrafluoroethylene membrane with a pore size of 0.22μm and collect the precipitate.

[0122] A2: Dry the precipitate collected in step A1 in a vacuum drying oven at 70°C for 6 hours;

[0123] A3: Disperse the intermediate material obtained in step A2 in deionized water, sonicate at 4°C for 30 min, and then separate using a centrifuge to obtain Ti2CT. X (S1).

[0124] Preparation of SnO2 nanoparticles (M1):

[0125] Weigh 3.0 g of oxalic acid dihydrate (H2C2O4·2H2O) and 0.25 g of stannous chloride dihydrate (SnCl2·2H2O) and add them to 60 mL of deionized water. Stir magnetically until the solids are completely dissolved and the solution becomes clear. Weigh 1.0 g of polyvinylpyrrolidone (PVP) and add it to the above solution. Stir the solution thoroughly until it becomes clear again. Transfer the reaction solution to a 100 mL polytetrafluoroethylene reactor and heat at 180 °C for 15 h.

[0126] After the reaction vessel was naturally cooled, the product was washed three times alternately with deionized water and ethanol, and then centrifuged at 9000 rpm for 10 min. The product was collected and dried in an oven at 60°C for 24 h. The product was then placed in a high-temperature crucible and placed stably in a muffle furnace and calcined at 500°C for 6 h to obtain SnO2 nanoparticles (M1).

[0127] Preparation of SnO2@Ti2CT X Methane gas-sensitive material (K1):

[0128] (1) Take 0.1g of Ti2CT X (S1) and 20g of the first solvent (obtained by mixing acetone and water in a volume ratio of 5:1) were mixed and then subjected to ultrasonic treatment. The ultrasonic treatment power was 600W, the temperature was 25℃, and the time was 60min. Then, 0.03g of SnO2 nanoparticles (M1) were added, and the mixture was stirred for 2h under light-protected conditions. Then, it was refluxed at 60℃ for 6h to obtain the intermediate product.

[0129] (2) The above intermediate product was separated into solid and liquid phases by centrifugation at a speed of 10,000 r / min. The obtained solid phase was then washed with deionized water and freeze-dried at -50°C for 8 h to obtain SnO2@Ti2CT. X Methane gas-sensitive material (K1).

[0130] Energy dispersive spectroscopy results showed that SnO2@Ti2CT X In the methane gas-sensitive material (K1), the loading (wt%) of SnO2 nanomaterials is 19%.

[0131] The product obtained in this embodiment was characterized using scanning electron microscopy, wherein SnO2@Ti2CT X Scanning electron microscope image as follows Figure 1 As shown in the scanning electron microscope image of SnO2 nanoparticles, Figure 2 As shown, the prepared SnO2@Ti2CT X Scanning electron microscope image of methane gas-sensitive material as shown below Figure 3 As shown.

[0132] Depend on Figure 1 It can be seen that Ti2CT X It consists of layered nanosheets, approximately 100 nm thick; made of Figure 2 It can be seen that SnO2 nanoparticles are spherical with a size of approximately 5–20 nm; from Figure 3 It can be seen that SnO2 nanoparticles loaded onto Ti2CT X SnO2@Ti2CT is formed on top X .

[0133] Example 2

[0134] Preparation of Ti2CT X (S2):

[0135] A1: Add 1g of Ti2AlCl to 40mL of 9mol / L HCl aqueous solution containing 1.5gLiF, stir at 45℃ for 38h, then centrifuge, wash with deionized water until the pH of the supernatant is 6, then vacuum filter the washed material with a polytetrafluoroethylene membrane with a pore size of 0.22μm, and collect the precipitate;

[0136] A2: Dry the precipitate collected in step A1 in a vacuum drying oven at 60°C for 8 hours;

[0137] A3: Disperse the intermediate material obtained in step A2 in deionized water, sonicate at 4°C for 30 min, and then separate using a centrifuge to obtain Ti2CT. X (S2);

[0138] SnO2 nanoparticles (M1) were prepared according to the method described in Example 1.

[0139] Preparation of SnO2@Ti2CT X Methane gas-sensitive material (K2):

[0140] (1) Take 0.1g of Ti2CT X (S2) and 30g of the first solvent (V(ethanol):V(water) = 4:1) were mixed and ultrasonically treated. The ultrasonic power was 800W, the temperature was 25℃, and the time was 30min. Then, 0.03g of SnO2 nanoparticles (M1) were added, and the mixture was stirred for 3h under light-protected conditions. Then, it was refluxed at 60℃ for 6h.

[0141] (2) The above intermediate product was separated into solid and liquid phases by centrifugation at a speed of 10,000 r / min. It was then washed with deionized water and freeze-dried at -50°C for 8 h to obtain SnO2@Ti2CT. X Methane gas-sensitive material (K2).

[0142] Energy dispersive spectroscopy results showed that SnO2@Ti2CT X In the methane gas-sensitive material (K2), the loading (wt%) of SnO2 nanomaterials is 18%.

[0143] The Ti2CT prepared in this embodiment X Characterization was performed using scanning electron microscopy, and the results showed that Ti2CT X It consists of layered nanosheets with a thickness of approximately 100 nm.

[0144] Example 3

[0145] Preparation of Ti2CT X (S3):

[0146] A1: Add 2g of Ti2AlC to 40mL of 9mol / L HCl aqueous solution containing 3gLiF, stir at 50℃ for 28h, then centrifuge, wash with deionized water until the pH of the supernatant is 6, then vacuum filter the washed material with a polytetrafluoroethylene membrane with a pore size of 0.22μm, and collect the precipitate.

[0147] A2: Dry the precipitate collected in step A1 in a vacuum drying oven at 70°C for 12 hours;

[0148] A3: Disperse the intermediate material obtained in step A2 in deionized water, sonicate at 10°C for 30 minutes, and then separate using a centrifuge to obtain Ti2CT. X (S3).

[0149] Preparation of SnO2 nanoparticles (M3):

[0150] Weigh 3.0 g of oxalic acid dihydrate (H2C2O4·2H2O) and 0.3 g of stannous chloride dihydrate (SnCl2·2H2O) and add them to 60 mL of deionized water. Stir magnetically until the solids are completely dissolved and the solution becomes clear. Weigh 1.1 g of polyvinylpyrrolidone (PVP) and add it to the above solution. Stir the solution thoroughly until it becomes clear again. Transfer the reaction solution to a 100 mL polytetrafluoroethylene reactor and heat at 160 °C for 20 h.

[0151] After the reaction vessel was naturally cooled, the product was washed three times alternately with deionized water and ethanol, and then centrifuged at 9000 rpm for 10 min. The product was collected and dried in an oven at 60°C for 24 h. The product was then placed in a high-temperature crucible and placed stably in a muffle furnace and calcined at 500°C for 8 h to obtain SnO2 nanoparticles (M3).

[0152] Preparation of SnO2@Ti2CT X Methane gas-sensitive material (K3):

[0153] (1) Take 0.1g of Ti2CT X (S3) and 20g of the first solvent (obtained by mixing ethanol and water in a volume ratio of 3:1) were mixed and then subjected to ultrasonic treatment. The ultrasonic treatment power was 600W, the temperature was 25℃, and the time was 40min. Then, 0.02g of SnO2 nanoparticles (M3) were added, and the mixture was stirred for 3h under light-protected conditions. Then, it was refluxed at 60℃ for 6h to obtain the intermediate product.

[0154] (2) The above intermediate product was separated into solid and liquid phases by centrifugation at a speed of 8000 r / min. The obtained solid phase was then washed with deionized water and freeze-dried at -70℃ for 6 h to obtain SnO2@Ti2CT. X Methane gas-sensitive material (K3).

[0155] Energy dispersive spectroscopy results showed that SnO2@Ti2CT X In the methane gas-sensitive material (K3), the loading (wt%) of SnO2 nanomaterials is 13%.

[0156] The product obtained in this embodiment was characterized using a scanning electron microscope, and the results are as follows: Figure 4 As shown.

[0157] Figure 4 The results showed that SnO2 nanoparticles were loaded onto Ti2CT X SnO2@Ti2CT is formed on top X .

[0158] Example 4

[0159] Preparation of Ti2CT X (S4):

[0160] A1: Add 1g of Ti2AlC to 50ml of 25% hydrofluoric acid and stir at 30℃ for 26h. Then centrifuge and wash with deionized water until the pH of the supernatant is 6. Then vacuum filter the washed material with a polytetrafluoroethylene membrane with a pore size of 0.22μm and collect the precipitate.

[0161] A2: Dry the precipitate collected in step A1 in a vacuum drying oven at 60°C for 7 hours;

[0162] A3: Disperse the intermediate material obtained in step A2 in deionized water, sonicate at 0°C for 30 minutes, and then separate using a centrifuge to obtain Ti2CT. X (S4).

[0163] SnO2 nanoparticles (M1) were prepared according to the method described in Example 1;

[0164] Preparation of SnO2@Ti2CT X Methane gas-sensitive material (K4):

[0165] (1) Take 0.1g of Ti2CT X (S4) and 40g of the first solvent (obtained by mixing acetone and ethanol in a volume ratio of 4:1) were mixed and then subjected to ultrasonic treatment at a power of 800W, a temperature of 25℃, and a time of 50min. Then, 0.04g of SnO2 nanoparticles (M1) were added, and the mixture was stirred for 2h under light-protected conditions. Then, it was refluxed at 60℃ for 6h to obtain the intermediate product.

[0166] (2) The above intermediate product was separated into solid and liquid phases by centrifugation at a speed of 10,000 r / min. The obtained solid phase was then washed with deionized water and freeze-dried at -60℃ for 8 h to obtain SnO2@Ti2CT. X Methane gas-sensitive material (K4).

[0167] Energy dispersive spectroscopy results showed that SnO2@Ti2CT X In the methane gas-sensitive material (K4), the loading (wt%) of SnO2 nanomaterials is 24%.

[0168] The Ti2CT prepared in this embodiment X Characterization was performed using scanning electron microscopy, and the results showed that Ti2CT X It consists of layered nanosheets with a thickness of approximately 85 nm.

[0169] Example 5

[0170] Preparation of Ti2CT X (S5):

[0171] A1: Add 1g of Ti2AlC to 40mL of 9mol / L HCl aqueous solution containing 3g LiF, stir at 35℃ for 40h, then centrifuge, wash with deionized water until the pH of the supernatant is 6, then vacuum filter the washed material with a polytetrafluoroethylene membrane with a pore size of 0.22μm, and collect the precipitate.

[0172] A2: Dry the precipitate collected in step A1 in a vacuum drying oven at 70°C for 8 hours;

[0173] A3: Disperse the intermediate material obtained in step A2 in deionized water, sonicate at 4°C for 30 min, and then separate using a centrifuge to obtain Ti2CT. X (S5)

[0174] Preparation of SnO2 nanosheets (M5):

[0175] Weigh 1g of tin dichloride dihydrate (SnCl2·2H2O) and dissolve it in 15mL of deionized water. After sonication, stir continuously with a magnetic stirrer for 10min to obtain a uniform dispersion. Then, add 0.5g of sodium hydroxide and stir vigorously for 10min. Then, transfer the above mixture to a 100mL high-pressure reactor lined with polytetrafluoroethylene and seal it in a muffle furnace at 180℃ for 4 hours.

[0176] After the reaction vessel naturally cooled to room temperature, the obtained yellow product was washed three times alternately with deionized water and anhydrous ethanol. The product was then placed in an oven and dried at 60°C for 24 hours. The product was then placed in a high-temperature crucible and stably placed into the muffle furnace. The product was calcined at 450°C for 8 hours to obtain SnO2 nanosheets (M5).

[0177] Preparation of SnO2@Ti2CT X Methane gas-sensitive material (K5):

[0178] (1) Take 0.1g of Ti2CT X (S5) and 35g of the first solvent (obtained by mixing ethanol and water in a volume ratio of 3:1) were mixed and then subjected to ultrasonic treatment. The ultrasonic treatment power was 500W, the temperature was 25℃, and the time was 50min. Then, 0.03g of SnO2 nanosheets (M5) were added, and the mixture was stirred for 2h under light-protected conditions. Then, it was refluxed at 50℃ for 6h to obtain the intermediate product.

[0179] (2) The above intermediate product was separated into solid and liquid phases by centrifugation at a speed of 8000 r / min. The obtained solid phase was then washed with deionized water and freeze-dried at -70℃ for 8 h to obtain SnO2@Ti2CT. X Methane gas-sensitive material (K5).

[0180] Energy dispersive spectroscopy results showed that SnO2@Ti2CT X In the methane gas-sensitive material (K5), the loading (wt%) of SnO2 nanomaterials is 16%.

[0181] The product obtained in this embodiment was characterized using scanning electron microscopy. The results showed that Ti2CT... X The nanosheets are layered nanosheets with a thickness of approximately 79 nm; the SnO2 nanosheets have a thickness of approximately 30–50 nm; SnO2 nanosheets are loaded onto Ti2CT. X SnO2@Ti2CT is formed on top X .

[0182] Example 6

[0183] Ti2CT was prepared according to the method described in Example 1. X (S1).

[0184] Preparation of SnO2 nanosheets (M6):

[0185] Weigh 1g of tin dichloride dihydrate (SnCl2·2H2O) and dissolve it in 15mL of deionized water. After sonication, stir continuously with a magnetic stirrer for 10min to obtain a uniform dispersion. Then, add 0.6g of sodium hydroxide and stir vigorously for 10min. Then, transfer the above mixture to a 100mL high-pressure reactor lined with polytetrafluoroethylene and seal it in a muffle furnace at 160℃ for 7 hours.

[0186] After the reaction vessel cooled to room temperature, the obtained yellow product was washed three times alternately with deionized water and anhydrous ethanol. The product was then dried in an oven at 60°C for 24 hours. The product was then placed in a high-temperature crucible and placed stably into the muffle furnace. The product was calcined at 500°C for 8 hours to obtain SnO2 nanosheets (M6).

[0187] Preparation of SnO2@Ti2CT X Methane gas-sensitive material (K6):

[0188] (1) Take 0.1g of Ti2CT X(S1) and 15g of the first solvent (acetone and water mixed in a volume ratio of 4:1) were mixed and then subjected to ultrasonic treatment. The ultrasonic treatment power was 500W, the temperature was 25℃, and the time was 50min. Then, 0.04g of SnO2 nanosheets (M6) were added, and the mixture was stirred for 2h under light-protected conditions. Then, it was refluxed at 50℃ for 6h to obtain the intermediate product.

[0189] (2) The above intermediate product was separated into solid and liquid phases by centrifugation at a speed of 8000 r / min. The obtained solid phase was then washed with deionized water and freeze-dried at -70℃ for 8 h to obtain SnO2@Ti2CT. X Methane gas-sensitive material (K6).

[0190] Energy dispersive spectroscopy results showed that SnO2@Ti2CT X In the methane gas-sensitive material (K6), the loading (wt%) of SnO2 nanomaterials is 23%.

[0191] Example 7

[0192] The method described in Example 3 was carried out, except that SnO2@Ti2CT was prepared. X When using methane gas-sensitive materials, the amount of SnO2 nanoparticles (M3) used is 0.04g.

[0193] Energy dispersive spectroscopy results showed that SnO2@Ti2CT X In the methane gas-sensitive material (K7), the loading (wt%) of SnO2 nanomaterials is 22%.

[0194] Example 8

[0195] The method described in Example 3 was carried out, except that SnO2@Ti2CT was prepared. X When using methane gas-sensitive materials, the amount of SnO2 nanoparticles (M3) used is 0.05g.

[0196] Energy dispersive spectroscopy results showed that SnO2@Ti2CT X In the methane gas-sensitive material (K8), the loading (wt%) of SnO2 nanomaterials is 28%.

[0197] Example 9

[0198] The method described in Example 3 was carried out, except that SnO2@Ti2CT was prepared. X When using methane gas-sensitive materials, SnO2 nanoparticles (M3) are replaced with SnO2 nanospheres (M9); wherein, SnO2 nanospheres (M9) are prepared according to the following steps:

[0199] Dissolve 0.644g SnSO4 in 30ml deionized water and stir magnetically for about 30 minutes. Then add 0.697g sodium benzenesulfonate (SDBS) to the solution. After stirring magnetically for about 1 hour, transfer the mixture to a 50ml hydrothermal reactor and react at 140℃ for 8 hours.

[0200] The product obtained by natural cooling to room temperature was washed five times by alternating centrifugation with ethanol and deionized water, and then dried at 80°C for 12 hours. Finally, the material was sintered in a muffle furnace at 600°C for 4 hours to obtain SnO2 nanospheres (M9).

[0201] Energy dispersive spectroscopy results showed that SnO2@Ti2CT X In the methane gas-sensitive material (K9), the loading (wt%) of SnO2 nanomaterials is 12%.

[0202] The SnO2 nanospheres prepared in this embodiment were characterized by scanning electron microscopy. The results showed that the diameter of the SnO2 nanospheres was about 600-700 nm.

[0203] Example 10

[0204] Preparation of Ti2CT X (S10):

[0205] A1: Add 2g of Ti3AlC2 to 40mL of 9mol / L HCl aqueous solution containing 3g LiF, stir at 25℃ for 20h, then centrifuge, wash with deionized water until the pH of the supernatant is 6, then vacuum filter the washed material with a polytetrafluoroethylene membrane with a pore size of 0.22μm, and collect the precipitate;

[0206] A2: Dry the precipitate collected in step A1 in a vacuum drying oven at 60°C for 8 hours;

[0207] A3: Disperse the intermediate material obtained in step A2 in deionized water, sonicate at 10°C for 30 minutes, and then separate using a centrifuge to obtain Ti2CT. X (S10);

[0208] Preparation of SnO2 nanospheres (M10):

[0209] Dissolve 0.644g SnSO4 in 30ml deionized water and stir magnetically for about 30 minutes. Then add 0.697g sodium benzenesulfonate (SDBS) to the solution. After stirring magnetically for about 1 hour, transfer the mixture to a 50ml hydrothermal reactor and react at 140℃ for 8 hours.

[0210] The product obtained by naturally cooling the reactor to room temperature was washed five times by alternating centrifugation with ethanol and deionized water, and then dried at 80°C for 12 hours. Finally, the material was sintered in a muffle furnace at 550°C for 4 hours to obtain SnO2 nanospheres (M10).

[0211] Preparation of SnO2@Ti2CT X Methane gas-sensitive material (K10):

[0212] (1) Take 0.1g of Ti2CT X (S10) and 20g of the first solvent (obtained by mixing ethanol and water in a volume ratio of 3:1) were mixed and then subjected to ultrasonic treatment. The ultrasonic treatment power was 700W, the temperature was 25℃, and the time was 60min. Then, 0.04g of SnO2 nanospheres (M10) were added, and the mixture was stirred for 3h under light-protected conditions. Then, it was refluxed at 50℃ for 6h to obtain the intermediate product.

[0213] (2) The above intermediate product was separated into solid and liquid phases by centrifugation at a speed of 8000 r / min. The obtained solid phase was then washed with deionized water and freeze-dried at -70℃ for 8 h to obtain SnO2@Ti2CT. X Methane gas-sensitive material (K10).

[0214] Energy dispersive spectroscopy results showed that SnO2@Ti2CT X In the methane gas-sensitive material (K5), the loading (wt%) of SnO2 nanomaterials is 25%.

[0215] The product obtained in this embodiment was characterized using scanning electron microscopy. The results showed that Ti2CT... X The nanosheets are layered nanosheets with a thickness of approximately 86 nm; the SnO2 nanospheres have a diameter of approximately 600–700 nm; SnO2 nanosheets are loaded onto Ti2CT. X SnO2@Ti2CT is formed on top X .

[0216] Comparative Example 1

[0217] The Ti2CT prepared in Example 1 X (S1) is a methane gas-sensitive material, and its microstructure is as follows: Figure 1 As shown.

[0218] Comparative Example 2

[0219] The SnO2 nanoparticles (M1) prepared in Example 1 were used as a methane gas-sensitive material, and their microstructure is as follows: Figure 2 As shown.

[0220] Comparative Example 3

[0221] The method described in Example 3 was carried out, except that SnO2@Ti2CT was prepared. X When using methane gas-sensitive materials, the amount of SnO2 nanoparticles (M3) used is 0.1g.

[0222] Energy dispersive spectroscopy results showed that SnO2@Ti2CT X In the methane gas-sensitive material (K5), the loading (wt%) of SnO2 nanomaterials is 4%.

[0223] Comparative Example 4

[0224] The method described in Example 3 was carried out, except that SnO2@Ti2CT was prepared. X When using methane gas-sensitive materials, the amount of SnO2 nanoparticles (M3) used is 0.005g.

[0225] Energy dispersive spectroscopy results showed that SnO2@Ti2CT X In the methane gas-sensitive material (K5), the loading (wt%) of SnO2 nanomaterials is 2%.

[0226] Test Example 1

[0227] The specific surface area of ​​the methane gas-sensitive materials prepared using the BET test examples and comparative examples is shown in Table 1 below.

[0228] Table 1

[0229]

[0230] As can be seen from Table 1, the methane gas-sensitive material prepared in the embodiments of the present invention has a high specific surface area, and the loading (wt%) of SnO2 nanomaterials in the methane gas-sensitive material is 5-35%.

[0231] Test Example 2

[0232] Sensing performance testing method: 2 mg of terpineol was placed in a mortar, then 1 mg of methane gas-sensitive material was added and ground for 3 minutes. The material was then coated onto the ceramic tube of the interdigitated gold electrode using a brush, and vacuum dried to form a sensing film, thus obtaining a methane sensor. The thickness of the sensing film and the initial resistance of the sensor were measured. The sensor was then placed in a test gas containing different volume concentrations of methane, and its resistance change was measured. The test gas was a mixture of methane and air. The test was conducted at room temperature (25℃). The sensor's response intensity S = ((RR) / (R ... 0) / R0)*100%, where R0 refers to the resistance of the sensor in air, and R refers to the resistance of the sensor in methane.

[0233] (1) Sensitivity test

[0234] The methane gas-sensitive materials prepared in Examples 1-10 and Comparative Examples 1-4 were tested using the above method, and the results are shown in Table 2 and... Figure 5 As shown, where, Figure 5 The graphs show the resistance changes of the sensors prepared in Examples 1, 1, and 2 after being exposed to methane of different concentrations for 10 seconds.

[0235] Table 2

[0236]

[0237]

[0238] From Table 2 and Figure 5 It can be seen that the sensor prepared by the methane gas-sensitive material obtained by the present invention can respond to methane with a volume concentration of 1 ppm within 10 seconds at room temperature. This indicates that the methane gas-sensitive material provided by the present invention has high sensitivity to methane, fast response speed, low lower limit of detectable methane volume concentration, low operating temperature, and low energy consumption.

[0239] (2) Selective testing

[0240] The selectivity of the sensor prepared by the methane gas-sensitive material prepared in Example 1 to methane relative to interfering gases was tested using the above method. The test gases were a mixture of air and methane, and a mixture of air and interfering gases, including ammonia, hydrogen sulfide, carbon monoxide and nitric oxide.

[0241] SnO2@Ti2CT prepared in Example 1 X The prepared sensor was placed in methane gas with a volume concentration of 1 ppm, and the results showed that the response intensity of the methane sensor was 8.93%.

[0242] SnO2@Ti2CT prepared in Example 1 X The prepared sensor was placed in a test gas with the same volume concentration of ammonia. The results showed that, at the same volume concentration, the response intensity of ammonia was only 10% of that of methane.

[0243] SnO2@Ti2CT prepared in Example 1 X The prepared sensor was placed in a test gas with the same volume concentration of hydrogen sulfide. The results showed that, at the same volume concentration, the response intensity of hydrogen sulfide was only 0.8% of that of methane.

[0244] SnO2@Ti2CT prepared in Example 1 XThe prepared sensor was placed in a test gas with the same volume concentration of carbon monoxide. The results showed that, at the same volume concentration, the response intensity of carbon monoxide was only 0.4% of that of methane.

[0245] SnO2@Ti2CT prepared in Example 1 X The prepared sensor was placed in a test gas with the same volume concentration of nitric oxide. The results showed that, at the same volume concentration, the response intensity of nitric oxide was only 1.2% of that of methane.

[0246] It should be noted that the preparation principles of Examples 2-10 are similar to those of Example 1. Therefore, the SnO2@Ti2CT prepared in Examples 2-10... X It also exhibits high selectivity for methane. Therefore, the SnO2@Ti2CT provided by this invention... X It offers a high degree of selectivity.

[0247] (3) Stability test

[0248] Using the above method, the SnO2@Ti2CT prepared in Example 3 was... X The prepared sensor was subjected to long-term testing for 1 ppm methane. After continuous use for 6 months (180 days), the change in response value was observed after 10 seconds of contact. The test results are shown in Table 3 below.

[0249] Table 3

[0250]

[0251] As can be seen from Table 3, after 6 months of continuous detection, the response value of the sensor made from the methane gas-sensitive material of the present invention remained within the range of 9.62% to 9.88%, with almost no change, indicating that the sensor made from the methane gas-sensitive material of the present invention has high stability.

[0252] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A methane gas-sensitive material, characterized in that, The methane gas-sensitive material includes Ti2CTx and loaded on the Ti2CTx. X SnO2 nanomaterials on; Based on the total weight of the methane gas-sensitive material, the content of the SnO2 nanomaterial is 5-35 wt%.

2. The methane gas-sensitive material according to claim 1, characterized in that, The specific surface area of ​​the methane gas-sensitive material is 100–600 m². 2 / g.

3. The methane gas-sensitive material according to claim 1 or 2, characterized in that, The SnO2 nanomaterial is selected from one or more of SnO2 nanoparticles, SnO2 nanosheets and SnO2 nanospheres; Preferably, the SnO2 nanoparticles have a size of 5–100 nm; Preferably, the thickness of the SnO2 nanosheets is 10–200 nm; Preferably, the SnO2 nanospheres have a diameter of 600–1500 nm.

4. A method for preparing a methane gas-sensitive material according to any one of claims 1-3, characterized in that, The method includes: (1) SnO2 nanomaterials and Ti2CT X Mix with the first solvent; (2) The material obtained in step (1) is subjected to solid-liquid separation, and then the obtained solid material is freeze-dried.

5. The method according to claim 4, characterized in that, In step (1), the Ti2CT X The weight ratio of SnO2 nanomaterials used is 1:0.1 to 0.5; Preferably, in step (1), the Ti2CT X The weight ratio of the amount of solvent used to the first solvent is 1:100 to 400; Preferably, in step (1), the mixing conditions include: a temperature of 0–100°C and a time of 2–36 h; Preferably, in step (1), the first solvent is selected from one or more of water, ethanol, methanol, chloroform and acetone; Preferably, in step (2), the freeze-drying conditions include: a temperature of -70 to -40°C and a time of 2 to 36 hours.

6. The method according to claim 4, characterized in that, The method also includes preparing Ti2CT according to the following steps X : Ti₂AlC is mixed with a solution containing fluoride ions and hydrogen ions, and then the first reaction is carried out.

7. The method according to claim 6, characterized in that, The conditions for the first reaction include: a temperature of 10–70°C and a time of 10–48 h.

8. The method according to claim 4, characterized in that, The SnO2 nanomaterial is selected from one or more of SnO2 nanoparticles, SnO2 nanosheets, and SnO2 nanospheres.

9. The method according to claim 8, characterized in that, The SnO2 nanoparticles are prepared according to the following steps: Oxalic acid dihydrate, stannous chloride dihydrate and water are mixed, then mixed with polyvinylpyrrolidone, and then the first hydrothermal reaction is carried out. The obtained product was washed, separated from its solid state, dried, and then subjected to a first calcination.

10. The method according to claim 9, characterized in that, The weight ratio of oxalic acid dihydrate, stannous chloride dihydrate, and polyvinylpyrrolidone is 1:0.05-0.2:0.2-0.

8. Preferably, the conditions for the first hydrothermal reaction include: a temperature of 100–200°C and a time of 5–30 h; Preferably, the conditions for the first roasting include: a temperature of 400–600°C and a time of 5–20 h.

11. A methane gas-sensitive material prepared by the method according to any one of claims 4-10.

12. A methane sensor, characterized in that, The methane sensor comprises the methane gas-sensitive material according to any one of claims 1-3 and 11.

13. A method for preparing the methane sensor according to claim 12, characterized in that, The method includes: mixing and grinding a methane gas-sensitive material with an organic solvent, and then coating it onto the surface of an electrode to form a sensing film; Preferably, the thickness of the sensing film is 200–5000 nm.

14. The application of the methane gas-sensitive material according to any one of claims 1-3 and 11 or the methane sensor according to claim 12 in methane detection.

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