Preparation method and application of Co-based two-dimensional metal oxide gas sensing material

Abstract

The invention discloses a preparation method and application of a Co-based two-dimensional metal oxide gas sensing material, and the preparation method comprises the following steps: reacting, centrifuging, drying and calcining a mixture containing an amine compound, a surfactant and a cobalt precursor to obtain the Co-based two-dimensional metal oxide gas sensing material, the calcination is carried out in an inactive atmosphere; the Co-based two-dimensional metal oxide in the Co-based two-dimensional metal oxide gas sensing material is CoO. According to the invention, the nano two-dimensional metal oxide is applied to the triethylamine gas sensor for the first time, and rapid, efficient and high-sensitivity detection of triethylamine gas at a relatively low temperature is realized. The two-dimensional structure improves the specific surface area of the material, and provides convenience for electron transmission.

Description

Technical Field

[0001] The present application relates to a preparation method and application of a Co-based two-dimensional metal oxide gas sensing material, and belongs to the technical field of nano-functional materials and environmental monitoring. Background Art

[0002] Triethylamine (TEA), as one of the common volatile organic compounds (VOCs), is often used as a solvent, curing agent, catalyst, etc. in industry. However, this organic compound is harmful to the human body and can cause irreversible chemical burns to the eyes and skin. In addition, the gas can cause strong irritation to the respiratory tract and can cause a series of complications such as pulmonary edema after inhalation. What's more serious is that if women inhale triethylamine, they may become infertile. According to the standards of the National Occupational Safety and Health Administration, the concentration of triethylamine in the air must not exceed 10ppm, so the detection of triethylamine in production and life is very necessary.

[0003] At present, the main methods for detecting triethylamine are chromatography, mass spectrometry, etc. These methods require expensive instruments and complex operations, and laboratory personnel need professional training before they can perform the detection. Therefore, it is of great significance to develop a triethylamine gas sensor with low cost, fast detection, high sensitivity and strong specificity.

[0004] Gas sensor technology can not only effectively detect the concentration and composition of the target gas, but also has the characteristics of small device size, portability and simple structure, and is easier to develop in the direction of miniaturization and intelligence. The key to preparing a gas sensor with good performance lies in the preparation of gas-sensitive sensing materials. Metal oxide semiconductor nanostructures have attracted extensive attention from researchers due to their low cost, simple preparation method and high detection sensitivity. However, single metal oxides also have disadvantages such as low stability, poor selectivity and high operating temperature, which limit their large-scale application. Therefore, the modification of the original metal oxide is conducive to the improvement of the gas-sensitive performance of the sensor. Summary of the invention

[0005] The basic mechanism of semiconductor resistive gas sensors is to change the resistance of the sensor by the reaction between the absorbed target gas molecules and the chemically adsorbed oxygen species on the surface of the sensing material, and to detect the concentration of the target gas by the change in resistance in the presence or absence of the target gas. Among the various types of gas sensing materials, metal oxide materials are widely favored by researchers due to their low cost, simple preparation method, strong controllability, etc., and have the prospect of large-scale industrialization.

[0006] The gas sensing performance of metal oxides is closely related to size, structure and morphology. A high BET specific surface area is conducive to increasing the contact between gas and the material surface, thereby improving the gas sensing performance. Therefore, designing metal oxide nanosheets with a two-dimensional structure is conducive to improving the BET specific surface area of ​​the original metal oxide material. The two-dimensional structure is also conducive to the adsorption of gas on the surface of the sensing material, thereby ultimately improving the gas sensing response. In addition, the edges of the two-dimensional structure have abundant surface dangling bonds and appropriate lattice distortion. These unique electronic structures are conducive to improving the accessibility of the material to the target gas. The ideal two-dimensional metal oxide platform is conducive to further improving the gas sensing performance of gas sensors and also lays the foundation for its functionalization. In summary, designing new two-dimensional semiconductor metal oxide nanostructures is the key to improving the performance of gas sensors.

[0007] The purpose of the present invention is to provide a low-cost and easy-to-operate preparation of a Co-based two-dimensional metal oxide gas sensing material, and to use the metal oxide in a gas sensor to achieve rapid and sensitive detection of trace triethylamine in production and life.

[0008] Based on this purpose, the present invention first prepares a new type of Co-based two-dimensional metal oxide gas sensing material, and utilizes the unique two-dimensional structure, large specific surface area and abundant edge surface dangling bonds of the material to detect trace triethylamine gas.

[0009] According to one aspect of the present application, a method for preparing a Co-based two-dimensional metal oxide gas sensing material is provided, the preparation method comprising:

[0010] reacting, centrifuging, drying and calcining a mixture containing an amine compound, a surfactant and a cobalt precursor to obtain the Co-based two-dimensional metal oxide gas sensing material;

[0011] The calcination is performed under an inert atmosphere.

[0012] Optionally, the Co-based two-dimensional metal oxide in the Co-based two-dimensional metal oxide gas sensing material is CoO.

[0013] Optionally, the preparation method includes: adding an amine compound to a certain amount of metal precursor, adding a mixture of water and ethanol and mixing evenly, then adding a surfactant, mixing evenly, reacting, centrifuging, drying, and calcining to obtain the Co-based two-dimensional metal oxide gas sensing material.

[0014] Optionally, the volume ratio of water to ethanol in the mixture of water and ethanol is selected from any value of 1:1, 1:2, 2:1 or a range between any two of the above.

[0015] Optionally, the surfactant is selected from at least one of oleic acid, oleylamine, sodium oleate, hexadecyltrimethylammonium bromide and sodium dodecyl sulfate.

[0016] Optionally, the mass ratio of the cobalt precursor: surfactant: amine compound is 0.5g~1g: 0.5g~1g: 0.5g~1g;

[0017] The mass of the amine compound is calculated by its own mass, the mass of the surfactant is calculated by its own mass, and the mass of the cobalt precursor is calculated by its own mass.

[0018] Optionally, the cobalt precursor is selected from at least one of cobalt sulfate, cobalt chloride, cobalt nitrate, cobalt acetate, and an organic cobalt compound.

[0019] Optionally, the amine compound is selected from at least one of urea, hexamethylenetetramine and ammonium chloride.

[0020] Optionally, the organic cobalt compound is selected from at least one of cobalt oxalate, cobalt acetylacetonate, and cobalt disodium ethylenediaminetetraacetate.

[0021] Optionally, the inert atmosphere is selected from at least one of nitrogen, argon and helium.

[0022] Optionally, the reaction temperature is 140-180° C., and the reaction time is 6-12 hours.

[0023] Optionally, the reaction temperature is selected from any value of 140°C, 150°C, 160°C, 170°C, 180°C or a range between any two of the above points.

[0024] Optionally, the reaction time is selected from any value among 6h, 8h, 10h, 12h or a range between any two of the above points.

[0025] Optionally, the drying temperature is 50-85° C., and the drying time is 6-12 hours.

[0026] Optionally, the drying temperature is selected from any value of 50°C, 60°C, 70°C, 80°C, 85°C or a range between any two of the above points.

[0027] Optionally, the drying time is selected from any value among 6h, 8h, 10h, 12h or a range between any two of the above points.

[0028] Optionally, the calcination temperature is 300-600° C., and the calcination time is 1-3 hours.

[0029] Optionally, the calcination temperature is selected from any value of 300°C, 350°C, 400°C, 500°C, 600°C or a range between any two of the above points.

[0030] Optionally, the calcination time is selected from any value of 1 h, 1.5 h, 2 h, 2.5 h, 3 h, or a range between any two of the above points.

[0031] Optionally, the number of centrifugation is 5 to 9 times.

[0032] Optionally, the number of centrifugation is selected from any value among 5 times, 7 times, 8 times, 9 times, or a range value between any two of the above points.

[0033] Optionally, the reaction further includes washing with polar and non-polar solvents.

[0034] Optionally, the non-polar solvent is selected from at least one of hexane, cyclohexane, carbon tetrachloride, benzene and toluene.

[0035] Optionally, the polar solvent is selected from at least one of water, ethanol and methanol.

[0036] According to another aspect of the present application, a Co-based two-dimensional metal oxide gas sensor material prepared by the preparation method described above is provided, and the BET surface area of ​​the Co-based two-dimensional metal oxide gas sensor material is 102-140.

[0037] According to another aspect of the present application, there is provided an application of the above-mentioned Co-based two-dimensional metal oxide gas sensing material in a triethylamine gas sensor.

[0038] Optionally, the detection limit of the triethylamine gas sensor for triethylamine is 100-120 ppb.

[0039] Optionally, the detection limit of the triethylamine gas sensor for triethylamine is selected from any value of 100 ppb, 105 ppb, 110 ppb, 115 ppb, 120 ppb or a range value between any two of the above points.

[0040] Optionally, the triethylamine gas sensor has better selectivity for triethylamine.

[0041] As a specific implementation, the present invention is implemented by the following technical solutions:

[0042] 1. Preparation of a Co-based two-dimensional metal oxide gas sensing material and its application in triethylamine gas sensing, the preparation method comprising the following preparation steps:

[0043] Step a, preparing a Co-based two-dimensional metal oxide gas sensing material;

[0044] Step b, constructing a triethylamine gas sensor;

[0045] Among them, the specific steps of step a for preparing Co-based two-dimensional metal oxide gas sensing material are:

[0046] (1) 0.5 g of urea was dissolved in a mixture of 20 mL of water and 30 mL of ethanol, and the mixture was stirred to form a uniform, transparent solution. Then, 0.5 g of hexadecyltrimethylammonium bromide (CTAB) was added to the solution under stirring, and the mixture was stirred to obtain a uniform solution.

[0047] (2) 0.5 g of cobalt precursor is further added to the uniform solution in (1), and stirred continuously to obtain a uniform system, and slowly poured into a stainless steel reactor lined with Teflon; the reactor is sealed and kept heated at 140-180° C. for 6-12 hours.

[0048] (3) Collect the product of step (2), wash it with a non-polar solvent, then wash it with a polar solvent, centrifuge it five times, and dry it under vacuum at 50°C.

[0049] (4) The product obtained in step (3) is placed in a muffle furnace and calcined at a temperature of 300 to 600° C. for 1 to 3 hours. The calcination conditions are in air and N 2 to obtain a Co-based two-dimensional metal oxide gas sensing material.

[0050] Step b: The specific construction steps of constructing the triethylamine gas sensor are:

[0051] (1) Using the interdigital electrode as the gas sensing electrode, add the prepared sample to an appropriate amount of solvent and mix to form a uniform slurry. Evenly drop the slurry on the electrode surface to form a film. Dry the interdigital electrode in an oven to evaporate the solvent to obtain a sensing film.

[0052] (2) The electrode obtained in step (1) is then aged in an oven to remove the organic solvent remaining on the electrode, thereby obtaining a gas sensing electrode with stable resistance. The gas sensing electrode is connected to a test instrument to obtain a triethylamine gas sensor.

[0053] Optionally, in step (1), the solvent is selected from at least one of ultrapure water, anhydrous ethanol, and acetone.

[0054] (1) A two-dimensional metal oxide gas-sensitive material is obtained by synthesizing an intermediate through a simple and effective hydrothermal method, achieving two-dimensional growth of the precursor through a surfactant, and then annealing the precursor;

[0055] (2) The material has a good two-dimensional nanosheet structure, and metal oxide nanostructures of different phases can be obtained by controlling the calcination conditions;

[0056] (3) The synergistic effect of the material's unique two-dimensional nanosheet structure, the abundant surface dangling bonds at the edge of the two-dimensional structure, and the appropriate lattice distortion ultimately leads to a significant improvement in sensor performance.

[0057] 2. The gas sensor based on the two-dimensional metal oxide gas-sensitive material is applied to the detection of triethylamine gas molecules, and its characteristics are that the specific detection method is:

[0058] (1) Using interdigital electrodes as gas sensing electrodes, 5-10 μL of slurry was dropped onto the surface of the substrate with Ag-Pd printed interdigital electrodes. The electrodes were dried at 65-100°C to form a sensing film.

[0059] (2) The modified interdigital electrode is heated in an oven to 180-200° C. for 12-24 hours to remove the residual organic solvent, thereby obtaining a triethylamine gas sensor to be tested.

[0060] (3) The gas sensor test is carried out using a static gas distribution method, that is, a certain amount of triethylamine liquid is evaporated on a hot stage using a micro-injector to obtain a certain concentration of triethylamine gas. The vaporized triethylamine gas evaporates in the test chamber, and the triethylamine gas molecules are detected by recording the resistance change of the sensor before and after the gas is introduced.

[0061] (4) Record the initial resistance of the sensor in air as R a , different concentrations of triethylamine were introduced into the test chamber, and the resistance when the gas was introduced was recorded as R g , with R g With R a Draw a working curve based on the relationship between the ratio and the concentration of triethylamine gas molecules.

[0062] The beneficial effects of this application include:

[0063] (1) The triethylamine gas sensor of the present invention is simple to prepare and easy to operate, and can achieve rapid, sensitive, and highly selective detection of triethylamine gas molecules at low cost. In addition, the test conditions close to room temperature provide conditions for portable detection of the sensor, and thus the sensor has market development prospects.

[0064] (2) The present invention is the first to synthesize a Co-based two-dimensional metal oxide gas sensing material by a simple hydrothermal synthesis followed by a subsequent heat treatment process, and adjusts the phase structure by changing the conditions during the subsequent calcination process.

[0065] This method has three main advantages: First, during the hydrothermal synthesis process, the decomposition of amine substances results in a precursor with high crystallinity, which provides a strong guarantee for the maintenance of the morphology during the subsequent heat treatment process and enhances the robustness of the material; second, under the action of surfactants, the precursor can achieve two-dimensional growth, thereby providing conditions for obtaining metal oxides with two-dimensional sheet structures. Third, during the annealing process, while the sample completes the transformation from precursor to metal oxide, a large number of rich oxygen defects are generated on the surface of the nanosheets. As adsorption active sites, the existence of defect states can enhance the material's adsorption capacity for the target gas. In addition, the regulation of the electronic state of the material surface by the defect structure also enhances the material's reactivity to the target gas. Therefore, the simple and effective preparation of this material has important scientific significance and application value.

[0066] (3) The present invention is the first to apply Co-based two-dimensional metal oxide gas sensing materials to the preparation of triethylamine gas sensors. The porous structure increases the BET surface area of ​​the material, providing more reactive sites for gas molecules. The presence of abundant oxygen defects significantly increases the accessibility of the material to target gas molecules, greatly improving the detection sensitivity of the triethylamine gas sensor. It also provides a technical reference for related sensors, such as photoelectrochemical sensors, electrochemical sensors, etc., and has a wide range of potential use value.

[0067] (4) The present invention applies the nano two-dimensional metal oxide to triethylamine gas sensor for the first time, achieving rapid, efficient and highly sensitive detection of triethylamine gas at a relatively low temperature. The two-dimensional structure increases the specific surface area of ​​the material and facilitates the transmission of electrons. In addition, the edge of the ultra-thin material has more surface unsaturated sites, which increases the accessibility of the material to the target gas molecules and greatly improves the detection sensitivity of the triethylamine gas sensor. The successful preparation of this material also provides a technical reference for related sensors, such as photoelectrochemical sensors, electrochemical sensors, etc., and has a wide range of potential use value. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 This is the XRD spectrum of the Co-based two-dimensional metal oxide gas sensing material precursor prepared in Example 1 of the present application.

[0069] Figure 2 This is a working curve diagram of the gas sensor in Example 11 of the present application.

[0070] Figure 3 This is a gas sensor selectivity diagram in Example 12 of the present application. DETAILED DESCRIPTION

[0071] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0072] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0073] In the examples of the present application, the instruments used to characterize the Co-based two-dimensional metal oxide gas sensing material are as follows:

[0074] Instrument Model Manufacturer RX I Fourier Transform Infrared Spectrometer Perkin Elmer TGA55 Thermogravimetric Analyzer TA Corporation Model Smart Lab SE XRD Nippon Rigaku Co., Ltd. Gemini 300 Field Emission Scanning Electron Microscope Carl Zeiss AG Optical and electrical integrated test platform CGS-MT KQ3200DB CNC Ultrasonic Cleaner Kunshan Ultrasonic Instrument Co., Ltd.

[0075] Example 1 Preparation of Co-based two-dimensional metal oxide gas sensing materials rich in oxygen defects

[0076] (1) 0.5 g of urea was dissolved in a mixture of 20 mL of water and 30 mL of ethanol, and the mixture was stirred to form a uniform, transparent solution. Then, 0.5 g of hexadecyltrimethylammonium bromide (CTAB) was added to the solution under stirring, and the mixture was stirred to obtain a uniform solution.

[0077] (2) 0.5 g of cobalt nitrate was further added to the homogeneous solution in (1), and the mixture was stirred continuously to obtain a uniform system, and the mixture was slowly poured into a stainless steel reactor lined with Teflon; the reactor was sealed and heated at 140° C. for 6 hours.

[0078] (3) The product of step (2) was collected, washed with n-hexane, then washed with ethanol and ultrapure water for five times, and centrifuged and dried under vacuum at 50° C. for 12 h.

[0079] (4) The product obtained in step (3) is placed in a muffle furnace and calcined in air at a temperature of 300° C. for 3 hours to obtain a Co-based two-dimensional metal oxide gas sensing material rich in oxygen defects with a BET surface area of ​​110. Figure 1 It can be seen that the obtained material has a good crystalline phase.

[0080] Example 2 Preparation of Co-based two-dimensional metal oxide gas sensing materials rich in oxygen defects

[0081] (1) 0.6 g of urea was dissolved in a mixture of 25 mL of water and 30 mL of ethanol, and the mixture was stirred to form a uniform, transparent solution. Then, 0.5 g of hexadecyltrimethylammonium bromide (CTAB) was added to the solution under stirring, and the mixture was stirred to obtain a uniform solution.

[0082] (2) 0.5 g of cobalt nitrate was further added to the homogeneous solution in (1), and the mixture was stirred continuously to obtain a uniform system, and the mixture was slowly poured into a stainless steel reactor lined with Teflon; the reactor was sealed and heated at 140° C. for 6 hours.

[0083] (3) The product of step (2) was collected, washed with n-hexane, then washed with ethanol and ultrapure water for five times, and centrifuged and dried under vacuum at 50° C. for 12 h.

[0084] (4) The product obtained in step (3) is placed in a muffle furnace and calcined in air at a temperature of 350° C. for 2 hours to obtain a Co-based two-dimensional metal oxide gas sensing material rich in oxygen defects with a BET surface area of ​​121.

[0085] Example 3 Preparation of Co-based two-dimensional metal oxide gas sensing materials rich in oxygen defects

[0086] (1) 0.5 g of urea was dissolved in a mixture of 20 mL of water and 30 mL of ethanol, and the mixture was stirred to form a uniform, transparent solution. Then, 0.5 g of hexadecyltrimethylammonium bromide (CTAB) was added to the solution under stirring, and the mixture was stirred to obtain a uniform solution.

[0087] (2) 0.5 g of cobalt nitrate was further added to the homogeneous solution in (1), and the mixture was stirred continuously to obtain a uniform system, and the mixture was slowly poured into a stainless steel reactor lined with Teflon; the reactor was sealed and heated at 140° C. for 6 hours.

[0088] (3) The product of step (2) was collected, washed with n-hexane, then washed with ethanol and ultrapure water for five times, and centrifuged and dried under vacuum at 50° C. for 12 h.

[0089] (4) The product obtained in step (3) is placed in a muffle furnace and calcined in air at a temperature of 350° C. for 1 hour to obtain a Co-based two-dimensional metal oxide gas sensing material rich in oxygen defects with a BET surface area of ​​107.

[0090] Example 4 Preparation of Co-based two-dimensional metal oxide gas sensing materials rich in oxygen defects

[0091] (1) 0.5 g of urea was dissolved in a mixture of 20 mL of water and 30 mL of ethanol, and the mixture was stirred to form a uniform, transparent solution. Then, 0.5 g of hexadecyltrimethylammonium bromide (CTAB) was added to the solution under stirring, and the mixture was stirred to obtain a uniform solution.

[0092] (2) 0.5 g of cobalt nitrate was further added to the homogeneous solution in (1), and the mixture was stirred continuously to obtain a uniform system, and the mixture was slowly poured into a stainless steel reactor lined with Teflon; the reactor was sealed and heated at 160° C. for 6 hours.

[0093] (3) The product of step (2) was collected, washed with n-hexane, then washed with ethanol and ultrapure water for five times, and centrifuged and dried under vacuum at 50° C. for 12 h.

[0094] (4) The product obtained in step (3) is placed in a muffle furnace and calcined in air at a temperature of 400° C. for 3 hours to obtain a Co-based two-dimensional metal oxide gas sensing material rich in oxygen defects with a BET surface area of ​​125.

[0095] Example 5 Preparation of Co-based two-dimensional metal oxide gas sensing materials rich in oxygen defects

[0096] (1) 0.5 g of urea was dissolved in a mixture of 20 mL of water and 30 mL of ethanol, and the mixture was stirred to form a uniform, transparent solution. Then, 0.5 g of hexadecyltrimethylammonium bromide (CTAB) was added to the solution under stirring, and the mixture was stirred to obtain a uniform solution.

[0097] (2) 0.5 g of cobalt chloride was further added to the homogeneous solution in (1), and the mixture was stirred continuously to obtain a uniform system, and the mixture was slowly poured into a stainless steel reactor lined with Teflon; the reactor was sealed and heated at 140° C. for 7 hours.

[0098] (3) The product of step (2) was collected, washed with n-hexane, then washed with ethanol and ultrapure water for five times, and centrifuged and dried under vacuum at 50° C. for 12 h.

[0099] (4) The product obtained in step (3) is placed in a muffle furnace and calcined at 300° C. in N 2 for 3 hours to obtain a Co-based two-dimensional metal oxide gas sensing material rich in oxygen defects with a BET surface area of ​​110.

[0100] Example 6

[0101] (1) 0.5 g of ammonium chloride was dissolved in a mixture of 20 mL of water and 30 mL of ethanol, and the mixture was stirred to form a uniform, transparent solution. Then, 0.5 g of oleic acid was added to the solution under stirring, and the mixture was stirred to obtain a uniform solution.

[0102] (2) 0.5 g of cobalt neodecanoate was further added to the homogeneous solution in (1), and stirred continuously to obtain a uniform system, and then slowly poured into a stainless steel reactor lined with Teflon; the reactor was sealed and kept heated at 160° C. for 6 hours.

[0103] (3) The product of step (2) was collected, washed with cyclohexane, and then washed with ethanol and ultrapure water for five times, and then centrifuged and dried under vacuum at 50° C. for 5 h.

[0104] (4) The product obtained in step (3) is placed in a muffle furnace and calcined at 500° C. in N 2 for 3 hours to obtain a Co-based two-dimensional metal oxide gas sensing material rich in oxygen defects with a BET surface area of ​​125.

[0105] Example 7

[0106] (1) 0.5 g of ammonium chloride was dissolved in a mixture of 20 mL of water and 30 mL of ethanol, and the mixture was stirred to form a uniform, transparent solution. Then, 0.5 g of oleic acid was added to the solution under stirring, and the mixture was stirred to obtain a uniform solution.

[0107] (2) 0.5 g of cobalt neodecanoate was further added to the homogeneous solution in (1), and stirred continuously to obtain a uniform system, and then slowly poured into a stainless steel reactor lined with Teflon; the reactor was sealed and kept heated at 150° C. for 8 hours.

[0108] (3) The product of step (2) was collected, washed with carbon tetrachloride, then washed with ethanol and ultrapure water for five times, centrifuged and dried under vacuum at 50° C. for 5 h.

[0109] (4) The product obtained in step (3) is placed in a muffle furnace and calcined at 400° C. in a N 2 atmosphere for 3 hours to obtain a Co-based two-dimensional metal oxide gas sensing material rich in oxygen defects with a BET surface area of ​​132.

[0110] Example 8

[0111] (1) 0.5 g of ammonium chloride was dissolved in a mixture of 20 mL of water and 30 mL of ethanol, and the mixture was stirred to form a uniform, transparent solution. Then, 0.5 g of sodium oleate was added to the solution under stirring, and the mixture was stirred to obtain a uniform solution.

[0112] (2) 0.5 g of cobalt acetylacetonate was further added to the homogeneous solution in (1), and the mixture was stirred continuously to obtain a uniform system, and the mixture was slowly poured into a stainless steel reactor lined with Teflon; the reactor was sealed and heated at 160° C. for 9 hours.

[0113] (3) The product of step (2) was collected, washed with carbon tetrachloride, then washed with ethanol and ultrapure water for five times, and centrifuged and dried under vacuum at 50° C. for 10 h.

[0114] (4) The product obtained in step (3) is placed in a muffle furnace and calcined at 400° C. in a N 2 atmosphere for 4 hours to obtain a Co-based two-dimensional metal oxide gas sensing material rich in oxygen defects with a BET surface area of ​​134.

[0115] Comparative Example 1

[0116] (1) Dissolve 0.5 g of ammonium chloride in a mixture of 20 mL of water and 30 mL of ethanol and stir to form a uniform, transparent solution.

[0117] (2) 0.5 g of cobalt acetylacetonate was further added to the homogeneous solution in (1), and the mixture was stirred continuously to obtain a uniform system, and the mixture was slowly poured into a stainless steel reactor lined with Teflon; the reactor was sealed and heated at 160° C. for 6 hours.

[0118] (3) The product of step (2) was collected, washed with cyclohexane, and then washed with ethanol and ultrapure water for five times, and then centrifuged and dried under vacuum at 50° C. for 5 h.

[0119] (4) The product obtained in step (3) is placed in a muffle furnace and calcined at 500° C. in N 2 for 3 hours to obtain a Co-based two-dimensional metal oxide gas sensing material rich in oxygen defects with a BET surface area of ​​125.

[0120] Example 9 Construction of triethylamine gas sensor

[0121] (1) Using the interdigital electrode as the gas sensing electrode, the Co-based two-dimensional metal oxide gas sensing material prepared in Example 1 was added to an appropriate amount of water and mixed to form a uniform slurry. Then 10 μL of the slurry was dropped on the surface of the substrate with the Ag-Pd printed interdigital electrode. The electrode was dried at 80°C to form a sensing film.

[0122] (2) The electrode obtained in step (1) is then heated in an oven to 200° C. for 5 hours to remove the residual organic solvent, thereby obtaining a triethylamine gas sensor.

[0123] Example 10 Construction of triethylamine gas sensor

[0124] (1) Using the interdigital electrode as the gas sensing electrode, the Co-based two-dimensional metal oxide gas sensing material prepared in Example 3 was added to an appropriate amount of anhydrous ethanol and mixed to form a uniform slurry. Then 5 μL of the slurry was dropped on the surface of the substrate with Ag-Pd printed interdigital electrodes. The electrode was dried at 60°C to form a sensing film.

[0125] (2) The electrode obtained in step (1) is then heated to 180° C. in an oven for 3 hours to remove the residual organic solvent, thereby obtaining a triethylamine gas sensor.

[0126] Embodiment 11

[0127] The triethylamine gas sensor prepared in Examples 1 to 8 is applied to the detection of triethylamine gas molecules, and the steps are as follows:

[0128] (1) Preparation of gas sensing electrode: The triethylamine gas sensor constructed in Example 10 was used as the working electrode;

[0129] (2) Preparation of standard gas: In order to obtain the required gas, triethylamine liquid was added into the test chamber using a micro syringe and evaporated directly;

[0130] (3) Drawing a working curve: Connect the electrode described in (1) to a gas sensor detection device, and distribute gas in a gas chamber using the method described in (2); test the resistance of the sensor before and after ventilation in a chamber with constant relative humidity and temperature; draw a working curve based on the relationship between the obtained resistance change and the concentration of triethylamine; the resistance change is expressed by R g / R a Indicates that R a refers to the resistance in ambient air, while R g is the resistance in the measured gas; the working curve takes the concentration of triethylamine gas molecules as the horizontal axis, R g / R a is plotted as the vertical axis. Figure 2 It can be seen that the sensor shows a good linear range for triethylamine.

[0131] Example 12

[0132] Inject interfering gas molecules with the same concentration as triethylamine into the chamber, test their gas-sensitive properties, and obtain the selectivity of the sensor. (The test method and test conditions are consistent with triethylamine gas detection); Figure 3 It can be seen that the sensor has good selectivity for triethylamine molecules.

[0133] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing a Co-based two-dimensional metal oxide gas sensing material, characterized in that: The preparation method comprises: reacting, centrifuging, drying and calcining a mixture containing an amine compound, a surfactant and a cobalt precursor to obtain the Co-based two-dimensional metal oxide gas sensing material; The calcination is performed under an inert atmosphere.

2. The preparation method according to claim 1, characterized in that: The surfactant is selected from at least one of oleic acid, oleylamine, sodium oleate, hexadecyltrimethylammonium bromide, and sodium dodecyl sulfate; Preferably, the mass ratio of the cobalt precursor: surfactant: amine compound is 0.5g~1g: 0.5g~1g: 0.5g~1g; Wherein, the mass of the amine compound is calculated by its own mass, the mass of the surfactant is calculated by its own mass, and the mass of the cobalt precursor is calculated by its own mass; Preferably, the Co-based two-dimensional metal oxide in the Co-based two-dimensional metal oxide gas sensing material is CoO.

3. The preparation method according to claim 1, characterized in that: The cobalt precursor is selected from at least one of cobalt sulfate, cobalt chloride, cobalt nitrate, cobalt acetate, and an organic cobalt compound; Preferably, the amine compound is selected from at least one of urea, hexamethylenetetramine and ammonium chloride.

4. The preparation method according to claim 2, characterized in that: The organic cobalt compound is selected from at least one of cobalt oxalate, cobalt acetylacetonate, and cobalt disodium ethylenediaminetetraacetate.

5. The preparation method according to claim 1, characterized in that: The inert atmosphere is selected from at least one of nitrogen, argon and helium; Preferably, the reaction temperature is 140-180° C., and the reaction time is 6-12 hours.

6. The preparation method according to claim 1, characterized in that: The drying temperature is 50-85°C and the drying time is 6-12h; Preferably, the calcination temperature is 300-600°C and the calcination time is 1-3h; Preferably, the number of centrifugation is 5 to 9 times.

7. The preparation method according to claim 1, characterized in that: The reaction further includes washing with polar and non-polar solvents; Preferably, the non-polar solvent is at least one selected from hexane, cyclohexane, carbon tetrachloride, benzene, and toluene; Preferably, the polar solvent is selected from at least one of water, ethanol and methanol.

8. The Co-based two-dimensional metal oxide gas sensing material prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The BET surface area of ​​the Co-based two-dimensional metal oxide gas sensing material is 102-140.

9. Use of the Co-based two-dimensional metal oxide gas sensing material according to claim 8 in a triethylamine gas sensor.

10. The use according to claim 9, characterized in that: The detection limit of triethylamine gas sensor for triethylamine is 100-120ppb.

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