Two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material and preparation method thereof

Abstract

The invention provides a two-dimensional multilayer titanium carbide / binary zinc-manganese oxide composite gas-sensitive material and a preparation method thereof, and the two-dimensional multilayer titanium carbide / binary zinc-manganese oxide composite gas-sensitive material is obtained by immersing alkali-treated two-dimensional multilayer titanium carbide into a zinc-manganese oxide seed growth solution and utilizing a seed layer induced self-assembly method. The compounding of the two-dimensional titanium carbide and the binary zinc-manganese oxide endows the material with a larger specific surface area, so that the number of active sites is increased, more oxygen vacancies are favorably formed, the concentration of adsorbed oxygen participating in a sensing reaction is increased, the gas-sensitive effect on NO2 is further improved, gas detection can be performed at room temperature, and the working temperature of the pure ZnO gas-sensitive material is reduced. Compared with a pure ZnO gas-sensitive material, the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material has an ultrahigh response value, a fast response speed and excellent selectivity on NO2 under the excitation of ultraviolet light, and has important practical significance in monitoring and real-time monitoring of NO2 in industrial production activities.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor metal oxide functional materials and gas sensitive sensor technology, and specifically relates to a two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas sensitive material and a preparation method thereof. Background Art

[0002] Nitrogen dioxide (NO2) is a toxic and harmful atmospheric pollutant gas. It comes from natural factors such as lightning and microbial life activities, and human factors such as fossil fuel combustion and automobile exhaust emissions. On the one hand, NO2 gas is the main cause of many environmental problems. NO2 emitted into the atmosphere not only causes atmospheric photochemical pollution, but also reacts with water molecules in the air to form nitric acid rain. The presence of NO2 also has a certain interference with the performance of chemical detection equipment. On the other hand, NO2 threatens human life and health, mainly damaging the human respiratory system. Long-term contact will cause coughing, chest tightness, respiratory tract infection, and even death. Therefore, timely and accurate monitoring of NO2 is of great significance to human health and environmental protection. In recent decades of research, metal oxide-based gas sensors are considered to be one of the most promising gas detection devices due to their low cost, real-time monitoring and simple preparation methods. Among them, ZnO, as a typical n-type semiconductor material, has a wide bandgap (3.37eV), strong chemical stability and excellent photoelectric properties, and has received great attention in NO2 gas-sensitive detection.

[0003] MXene is a new type of two-dimensional nanomaterial with rich surface functional groups. n+1 X n T z It represents, where M refers to transition metal, X refers to carbon and / or nitrogen, T x Indicates such as O 2- OH - 、F - The surface groups of MXene are n = 1, 2, 3. The suffix "ene" of MXene indicates their similarity to graphene. MXenes materials have attracted people's attention due to their advantages such as large specific surface area, high conductivity, and adjustable surface end groups. They have broad application prospects in energy storage, catalysis, electromagnetic shielding and sensors. Among the many MXene materials, two-dimensional titanium carbide Ti3C2T x It is the earliest discovered and most studied material. In recent years, researchers have combined Ti3C2T x MXene and metal oxides are combined to construct nanocomposite gas-sensitive materials to prepare high-performance, low-power gas sensors, which have potential application prospects in gas sensing. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] The present invention provides a two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material and a preparation method thereof, so as to solve the technical problems of high working temperature and low response value of pure ZnO gas-sensitive material to NO2.

[0006] (II) Technical solution

[0007] In order to solve the above technical problems, the present invention proposes a method for preparing a two-dimensional multilayer titanium carbide / binary zinc-manganese oxide composite gas-sensitive material. The method for preparing the composite gas-sensitive material comprises the following steps: using anhydrous zinc acetate, manganese acetate tetrahydrate and two-dimensional multilayer titanium carbide treated with alkali as raw materials, methanol as solvent, sodium hydroxide and zinc hydroxide precursors as growth solutions, and hexadecyltrimethylammonium bromide as surfactant; and adopting a seed layer induced self-assembly method to prepare a two-dimensional multilayer titanium carbide / zinc-manganese oxide composite gas-sensitive material precursor. After heat treatment in an air atmosphere, a two-dimensional multilayer titanium carbide / binary zinc-manganese oxide composite gas-sensitive material consisting of multiple layers of titanium carbide and zinc-manganese oxide nanosheets grown on the surface and between layers of the titanium carbide is obtained.

[0008] Furthermore, the preparation method specifically comprises the following steps:

[0009] S1. The two-dimensional multilayer titanium carbide is dispersed in a potassium hydroxide solution, stirred, ultrasonically dispersed, dissolved, centrifuged and dried to obtain an alkali-treated two-dimensional multilayer titanium carbide;

[0010] S2. dissolving the alkali-treated two-dimensional multilayer titanium carbide in methanol, stirring magnetically, dispersing and dissolving by ultrasonic, then adding anhydrous zinc acetate, manganese acetate tetrahydrate and hexadecyltrimethylammonium bromide, stirring to obtain a first solution; dissolving sodium hydroxide in methanol, stirring magnetically to obtain a second solution; mixing the first solution and the second solution, stirring magnetically, and standing at room temperature to obtain a two-dimensional multilayer titanium carbide / binary zinc-manganese oxide seed layer solution, centrifuging and drying the precipitate to obtain a two-dimensional multilayer titanium carbide / binary zinc-manganese oxide seed layer powder;

[0011] S3. dissolving sodium hydroxide in deionized water, stirring, adding a zinc hydroxide precursor, stirring, and then adding a two-dimensional multilayer titanium carbide / binary zinc manganese oxide seed layer powder to obtain a mixed solution;

[0012] S4. In a water bath, the mixed solution obtained in step S3 is stirred at a constant temperature by magnetic force, and the precipitate is dried after centrifugation to obtain a two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material precursor;

[0013] S5. The two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material precursor is subjected to high-temperature heat treatment in an air atmosphere to obtain a two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material.

[0014] Furthermore, in step S1, the two-dimensional multilayer titanium carbide is dispersed in a 2 mol / L potassium hydroxide solution, stirred for 4 hours at a stirring rate of 500 r / min, and ultrasonically dispersed and dissolved for 1 hour. After the reaction, it is centrifuged, washed, and dried with ionized water to obtain alkali-treated two-dimensional multilayer titanium carbide.

[0015] Further, in step S2, the alkali-treated two-dimensional multilayer titanium carbide is dissolved in methanol, magnetically stirred for 20 minutes at a stirring rate of 500 r / min, and ultrasonically dispersed and dissolved for 30 minutes, and then anhydrous zinc acetate, manganese acetate tetrahydrate and hexadecyltrimethylammonium bromide are added, the molar ratio of the zinc source to the manganese source is 1:2, and stirred for 2 hours to obtain a first solution; sodium hydroxide is dissolved in methanol, magnetically stirred for 20 minutes at a stirring rate of 500 r / min to obtain a second solution; the first solution and the second solution are mixed, magnetically stirred for 10 minutes at a stirring rate of 500 r / min, and allowed to stand at room temperature for 2 hours to obtain a two-dimensional multilayer titanium carbide / binary zinc manganese oxide seed layer solution, which is washed after centrifugation, and the precipitate is dried to obtain a two-dimensional multilayer titanium carbide / binary zinc manganese oxide seed layer powder.

[0016] Further, in step S3, sodium hydroxide is dissolved in deionized water, magnetically stirred for 10 minutes at 25°C and 500r / min, a zinc hydroxide precursor is added, the mass ratio of sodium hydroxide to zinc hydroxide precursor is 2:1, and stirring is carried out for 10 minutes; in step S4, the mixed solution obtained in step S3 is magnetically stirred at a constant temperature for 40 minutes at a water bath temperature of 80°C and a stirring rate of 300r / min; in step S5, a high-temperature heat treatment is carried out in an air atmosphere to calcine the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material precursor at 300°C for 2 hours at a heating rate of 3°C / min.

[0017] In addition, the present invention also proposes a two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material, and the composite gas-sensitive material is prepared by the above method.

[0018] In addition, the present invention also proposes an application of a two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material, and applies the above two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material to gas sensing detection.

[0019] Furthermore, the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material was used to detect NO2 at 25°C and under ultraviolet light.

[0020] In addition, the present invention also proposes a method for preparing a gas sensitive element, which comprises mixing the above-mentioned two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas sensitive material with deionized water to form a two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas sensitive material slurry; drop-coating the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas sensitive material slurry on an Ag-Pd electrode, and naturally drying it at room temperature to obtain a gas sensitive element.

[0021] Furthermore, the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material is placed in an agate mortar, deionized water is added and ground to form a two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material slurry; a rubber-tipped dropper is used to drop the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material slurry onto the Ag-Pd electrode.

[0022] (III) Beneficial effects

[0023] The present invention proposes a two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material and a preparation method thereof. The two-dimensional multilayer titanium carbide is subjected to surface alkali treatment to obtain an alkali-treated two-dimensional multilayer titanium carbide, and then the alkali-treated two-dimensional multilayer titanium carbide is immersed in a zinc manganese oxide seed growth solution, and a seed layer induced self-assembly method is used to obtain a two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material. The preparation process of the method is simple and the cost is low. The composite of the two-dimensional titanium carbide and the binary zinc manganese oxide gives the material a larger specific surface area, increases the number of active sites, and is conducive to the formation of more oxygen vacancies, thereby increasing the concentration of adsorbed oxygen participating in the sensing reaction, further improving the gas-sensitive effect of NO2, and being able to perform gas detection at room temperature, reducing the working temperature of the pure ZnO gas-sensitive material. Compared with the pure ZnO gas-sensitive material, the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material has an ultra-high response value, a fast response speed and excellent selectivity to NO2 under ultraviolet light excitation, and has important practical significance for monitoring and real-time monitoring of NO2 in industrial production activities. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The XRD diffraction pattern of the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material prepared in Example;

[0025] Figure 2 This is a scanning electron microscope (SEM) image of a two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material prepared in Example;

[0026] Figure 3 The Fourier transform infrared spectrum (FT-IR) of the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material prepared in Example;

[0027] Figure 4The two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material prepared in the embodiment shows a NO2 response curve of 100ppm-250ppb at 25°C and under ultraviolet light;

[0028] Figure 5 This is an enlarged view of the response curve of the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material prepared in Example to 1ppm-250ppb NO2 under ultraviolet light at 25°C;

[0029] Figure 6 The response curve of the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material prepared in the example to 100 ppm NO2 at 25°C and under ultraviolet light;

[0030] Figure 7 Response curves of the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material prepared in the example to 100 ppm NO2 and the other five interfering gases under ultraviolet light at 25°C. DETAILED DESCRIPTION

[0031] In order to make the purpose, content and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below in conjunction with the drawings and examples.

[0032] This embodiment provides a method for preparing a two-dimensional multilayer titanium carbide / binary zinc and manganese oxide composite gas-sensitive material with a zinc and manganese molar ratio of 1:2, which specifically includes the following steps:

[0033] S1. Weigh 0.3 g of two-dimensional multilayer titanium carbide and disperse it in 40 ml of 2 mol / L (4.48 g) potassium hydroxide solution. Stir it magnetically at 25°C and 500 r / min for 4 hours. Collect the product by centrifugation after the reaction, wash it with deionized water three times, and dry it at 60°C for 12 hours to obtain alkali-treated two-dimensional multilayer titanium carbide.

[0034] S2. Dissolve 0.1 g of the alkali-treated two-dimensional multilayer titanium carbide obtained in step S1 in 50 ml of methanol, stir magnetically at 25° C. and 500 r / min for 20 min, disperse and dissolve ultrasonically for 30 min, then add 0.06 g of anhydrous zinc acetate, 0.16 g of manganese acetate tetrahydrate and 0.006 g of hexadecyltrimethylammonium bromide, stir magnetically at 25° C. and 500 r / min for 2 h to obtain a first solution, dissolve 0.02 g of sodium hydroxide in 50 ml of methanol, stir magnetically at 25° C. and 500 r / min for 20 min to obtain a second solution, mix the first solution and the second solution, stir magnetically at 25° C. and 500 r / min for 10 min, let stand for 2 h to obtain a two-dimensional multilayer titanium carbide / binary zinc-manganese oxide seed layer solution, collect the product by centrifugation after the reaction, wash it three times with ionized water, and dry it at 60° C. for 12 h to obtain 0.05 g of two-dimensional multilayer titanium carbide / binary zinc-manganese oxide seed layer powder.

[0035] S3. Dissolve 0.5 g of sodium hydroxide in 30 ml of deionized water, stir magnetically for 10 min at 25°C and 500 r / min, add 0.25 g of zinc hydroxide precursor, stir magnetically for 10 min, and then add 0.05 g of the two-dimensional multilayer titanium carbide / binary zinc manganese oxide seed layer powder obtained in step S2 to obtain a mixed solution.

[0036] S4. Under the conditions of a water bath temperature of 80°C and a stirring rate of 300 r / min, the mixed solution of step S3 was magnetically stirred at a constant temperature for 40 min. After the reaction, the product was collected by centrifugation, washed with deionized water three times, and dried at 60°C for 12 h to obtain 60 mg of a two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material precursor.

[0037] S5. Spread 60 mg of the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material precursor obtained in step S4 on a ceramic crucible, and calcine it in a muffle furnace at 300°C (heating rate 3°C / min) for 2 hours to obtain 55 mg of the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material.

[0038] The specific steps of preparing a gas sensor using the above two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas sensing material are as follows:

[0039] S1. Weigh 15 mg of two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas sensing material into an agate mortar, add 2 ml of deionized water, and grind into a slurry with appropriate intensity.

[0040] S2. Use a rubber-tipped dropper to drop the slurry onto a cleaned Ag-Pd electrode (14 mm×7 mm), and dry it naturally at room temperature to obtain a gas sensitive element as a gas sensor.

[0041] Before testing, the gas sensor was vacuum dried at 60 °C for 12 h to make the molecular structure of the material tighter for better test results.

[0042] The sensitivity is calculated by using the resistance value of the material in the target gas (Rg) and the resistance value of the material in the air environment (Ra), and defining the gas-sensitive response value as S = (Rg / Ra).

[0043] Figure 1 The XRD diffraction pattern of the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material obtained in this embodiment shows that the diffraction peaks at 31.7°, 34.4°, 36.2°, 47.5°, 56.6°, 62.8°, 66.3°, 67.8° and 69.1° are consistent with the ZnO standard spectrum (PDF#70-2551), corresponding to the (100), (002), (101), (102), (110), (103), (200), (112) and (201) crystal planes of the hexagonal fibrous mineral phase ZnO, respectively, and no other crystal phase impurity peaks are found; while the peak at 2.9° is consistent with the Ti3C2T x The (002) crystal planes of the precursor (Ti3AlC2) are consistent, proving that the present invention successfully synthesizes a two-dimensional multilayer titanium carbide / binary zinc-manganese oxide composite gas-sensitive material.

[0044] Depend on Figure 2 It can be seen that the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material presents an obvious lamellar structure, in which many small zinc manganese oxide nanosheets are about 300-500nm in diameter and are tightly attached to the interlayers and surface of the two-dimensional multilayer titanium carbide.

[0045] Figure 3 This is the Fourier infrared spectrum of the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material obtained in this example, in which the simultaneous existence of Ti-O bonds and Zn-O bonds once again proves the successful synthesis of the two-dimensional multilayer titanium carbide / binary zinc manganese oxide material.

[0046] Figure 4 This is the response of the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material obtained in this example to 100ppm-250ppb NO2 under ultraviolet light at 25°C. It can be seen that its response value increases significantly with the increase of NO2 concentration.

[0047] Figure 5This is an enlarged view of the response of the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material obtained in this example to 1ppm-250ppb NO2 under ultraviolet light at 25°C. It is worth noting that the detection limit of the sensor prepared from the above material is 250ppb, indicating that the sensor is an ideal candidate sensor for the actual detection of NO2.

[0048] Figure 6 From the response curve of the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material obtained in this embodiment to 100 ppm NO2 at 25°C and ultraviolet light, it can be clearly seen that the response time for the response to reach 280 is 8s, and the recovery time is 40s. The fast response recovery speed is due to the large specific surface area of ​​the material and the rapid migration of photogenerated carriers under ultraviolet light excitation.

[0049] Figure 7 The following are the response curves of the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material obtained in this example to 100 ppm NO2 and the other five interfering gases under ultraviolet light at 25°C. The results show that the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material has outstanding selectivity for NO2 and can achieve complete response to NO2 in a complex gas environment.

[0050] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a two-dimensional multilayer titanium carbide / binary zinc-manganese oxide composite gas-sensitive material, characterized in that: The composite gas-sensitive material preparation method comprises the following steps: using anhydrous zinc acetate, manganese acetate tetrahydrate and alkali-treated two-dimensional multilayer titanium carbide as raw materials, methanol as solvent, sodium hydroxide and zinc hydroxide precursors as growth solutions, and hexadecyltrimethylammonium bromide as surfactant, adopting a seed layer induced self-assembly method to prepare a two-dimensional multilayer titanium carbide / zinc-manganese oxide composite gas-sensitive material precursor, and after heat treatment in an air atmosphere, obtaining a two-dimensional multilayer titanium carbide / binary zinc-manganese oxide composite gas-sensitive material composed of multiple layers of titanium carbide and zinc-manganese oxide nanosheets grown on the surface and between layers of titanium carbide.

2. The method for preparing the two-dimensional multilayer titanium carbide / binary zinc-manganese oxide composite gas-sensitive material according to claim 1, characterized in that: The preparation method specifically comprises the following steps: S1. The two-dimensional multilayer titanium carbide is dispersed in a potassium hydroxide solution, stirred, ultrasonically dispersed, dissolved, centrifuged and dried to obtain an alkali-treated two-dimensional multilayer titanium carbide; S2. dissolving the alkali-treated two-dimensional multilayer titanium carbide in methanol, magnetically stirring, ultrasonically dispersing and dissolving, and then adding anhydrous zinc acetate, manganese acetate tetrahydrate and hexadecyltrimethylammonium bromide, stirring to obtain a first solution; Dissolving sodium hydroxide in methanol, and stirring magnetically to obtain a second solution; mixing the first solution and the second solution, stirring magnetically, and standing at room temperature to obtain a two-dimensional multilayer titanium carbide / binary zinc manganese oxide seed layer solution, centrifuging and drying the precipitate to obtain a two-dimensional multilayer titanium carbide / binary zinc manganese oxide seed layer powder; S3. dissolving sodium hydroxide in deionized water, stirring, adding a zinc hydroxide precursor, stirring, and then adding a two-dimensional multilayer titanium carbide / binary zinc manganese oxide seed layer powder to obtain a mixed solution; S4. In a water bath, the mixed solution obtained in step S3 is stirred at a constant temperature by magnetic force, and the precipitate is dried after centrifugation to obtain a two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material precursor; S5. The two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material precursor is subjected to high-temperature heat treatment in an air atmosphere to obtain a two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material.

3. The method for preparing the two-dimensional multilayer titanium carbide / binary zinc-manganese oxide composite gas-sensitive material according to claim 2, characterized in that: In step S1, the two-dimensional multilayer titanium carbide is dispersed in a potassium hydroxide solution with a concentration of 2 mol / L, stirred for 4 hours at a stirring rate of 500 r / min, and ultrasonically dispersed and dissolved for 1 hour. After the reaction, it is centrifuged, washed, and dried with ionized water to obtain alkali-treated two-dimensional multilayer titanium carbide.

4. The method for preparing a two-dimensional multilayer titanium carbide / binary zinc-manganese oxide composite gas-sensitive material according to claim 2, characterized in that: In step S2, the alkali-treated two-dimensional multilayer titanium carbide is dissolved in methanol, magnetically stirred for 20 minutes at a stirring rate of 500 r / min, ultrasonically dispersed and dissolved for 30 minutes, and then anhydrous zinc acetate, manganese acetate tetrahydrate and hexadecyltrimethylammonium bromide are added, the molar ratio of the zinc source to the manganese source is 1:2, and stirred for 2 hours to obtain a first solution; Dissolve sodium hydroxide in methanol, and stir magnetically for 20 minutes at a stirring rate of 500 r / min to obtain a second solution; The first solution and the second solution were mixed, magnetically stirred for 10 minutes at a stirring rate of 500 r / min, and allowed to stand at room temperature for 2 hours to obtain a two-dimensional multilayer titanium carbide / binary zinc manganese oxide seed layer solution, which was centrifuged and washed, and the precipitate was dried to obtain a two-dimensional multilayer titanium carbide / binary zinc manganese oxide seed layer powder.

5. The method for preparing the two-dimensional multilayer titanium carbide / binary zinc-manganese oxide composite gas-sensitive material according to claim 2, characterized in that: In step S3, sodium hydroxide is dissolved in deionized water, magnetically stirred for 10 minutes at 25°C and 500r / min, a zinc hydroxide precursor is added, the mass ratio of sodium hydroxide to zinc hydroxide precursor is 2:1, and stirring is carried out for 10 minutes; in step S4, the mixed solution obtained in step S3 is magnetically stirred at a constant temperature for 40 minutes at a water bath temperature of 80°C and a stirring rate of 300r / min; in step S5, a high-temperature heat treatment is carried out in an air atmosphere to calcine the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material precursor at 300°C for 2 hours at a heating rate of 3°C / min.

6. A two-dimensional multilayer titanium carbide / binary zinc-manganese oxide composite gas-sensitive material, characterized in that: The composite gas-sensitive material is prepared by the method according to any one of claims 1 to 5.

7. Application of a two-dimensional multilayer titanium carbide / binary zinc-manganese oxide composite gas-sensitive material, characterized in that: The two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material described in claim 6 is applied to gas sensing detection.

8. The use of the two-dimensional multilayer titanium carbide / binary zinc-manganese oxide composite gas-sensitive material as claimed in claim 7, characterized in that: The two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material is used to detect NO2 at 25°C and under ultraviolet light.

9. A method for preparing a gas sensor, characterized in that: The preparation method comprises mixing the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material described in claim 6 with deionized water to form a two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material slurry; drop-coating the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material slurry on an Ag-Pd electrode, and drying it naturally at room temperature to obtain a gas-sensitive element.

10. The method for preparing a gas sensor according to claim 9, characterized in that: The preparation method comprises the following steps: placing the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material in an agate mortar, adding deionized water and grinding the material to form a two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material slurry; and using a rubber-tipped dropper to drop the two-dimensional multilayer titanium carbide / binary zinc manganese oxide composite gas-sensitive material slurry onto an Ag-Pd electrode.

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