Au-N-Ti3C2Tx gas sensitive material as well as preparation method and application thereof

Abstract

The invention discloses an Au-N-Ti3C2Tx gas sensitive material as well as a preparation method and application thereof, and belongs to the technical field of gas sensitive materials. The chemical formula of the gas sensitive material is Aua-Nb-Ti3C2Tx, a is greater than or equal to 1 and less than or equal to 3, and b is greater than or equal to 1 and less than or equal to 4; the structure of the gas sensitive material is that lamellar gold nanoparticles are loaded on a two-dimensional accordion-shaped Ti < 3 > C < 2 > T < x > nanosheet. The interlayer spacing of the Ti < 3 > C < 2 > T < x > nanosheets is 0.2 nm to 0.3 nm; the particle size of the gold nanoparticles ranges from 6 nm to 8 nm, and the interlamellar spacing of the gold nanoparticles ranges from 0.2 nm to 0.3 nm. According to the Au-N-Ti3C2Tx gas sensitive material as well as the preparation method and the application thereof, gold nanoparticle loading, N atom doping and Ti3C2Tx gas sensitive material are utilized to construct a composite material, Ti3C2Tx lattice dislocation, Schottky barrier formation and noble metal catalysis are realized, and the problems of low sensor response, poor stability and resistance baseline value drift are solved; and high-selectivity detection of NH3 at room temperature is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of gas-sensitive materials, and particularly relates to an Au-N-Ti 3 C 2 T x gas-sensitive material, its preparation method and application. Background Art

[0002] With the rapid growth of the economic and technological levels, the accompanying environmental pollution problems have become increasingly severe, and at the same time, the human health problems caused have occurred frequently. Therefore, people have also paid more and more attention to the detection of the surrounding environmental pollution and the monitoring of the human health problems caused. Therefore, designing an efficient gas sensor with characteristics such as portability and simple structure has become one of the forefront hotspots in the fields of environmental and disease detection.

[0003] At present, metal oxide semiconductor gas sensors have attracted much attention due to their advantages such as low cost, easy manufacturing, high sensitivity, and short response / recovery time. However, the intrinsic carrier concentration of traditional gas sensors based on metal oxide semiconductors is much smaller than the carrier concentration of impurity ionization, which means that the device usually needs a relatively high working temperature (200 - 400 °C) to achieve the optimal gas-sensitive performance. The high working temperature has also become an obstacle to the miniaturization and integration development of the sensor system. Facing the problem that traditional metal oxide semiconductor gas sensors need to work at a relatively high temperature, based on the research and development of new materials and the regulation of surface and interface electrons, constructing a gas sensor with excellent performance at low temperature or even room temperature is one of the important breakthroughs for future gas sensors.

[0004] Two-dimensional Ti 3 C 2 T x materials have realized the effective detection of gases at low temperature or even room temperature due to their controllable bandgap structure and rich surface functional groups. However, the response of existing Ti 3 C 2 T x gas sensors is lower than that of oxides, the recovery ability is poor, and the Ti 3 C 2 T x material sensors have problems such as poor response stability and drift of the resistance baseline value. Especially when Ti 3 C 2 T x is tightly combined with oxygen molecules, their sensing characteristics cannot be maintained for a long time. Summary of the Invention

[0005] The object of the present invention is to provide an Au-N-Ti 3 C 2 T xGas-sensitive material, its preparation method and application, using Au nanoparticle loading, N atom doping and combination with Ti 3 C 2 T x to construct a composite material with the gas-sensitive material, achieving lattice dislocation of Ti 3 C 2 T x , formation of Schottky barriers and catalytic effects of noble metals, solving the problems of low sensor response, poor stability and drift of the resistance baseline value; achieving high-selectivity detection of NH 3 at room temperature.

[0006] To achieve the above object, the present invention provides a Au-N-Ti 3 C 2 T x gas-sensitive material, and the chemical formula of the gas-sensitive material is Au a -N b -Ti 3 C 2 T x , where 1 ≤ a ≤ 3 and 1 ≤ b ≤ 4; the structure of the gas-sensitive material is that sheet-like Au nanoparticles are loaded on two-dimensional accordion-shaped Ti 3 C 2 T x nanosheets.

[0007] Preferably, the layer spacing of the Ti 3 C 2 T x nanosheets is 0.2 nm - 0.3 nm; the particle size of the Au nanoparticles is 6 nm - 8 nm, and the sheet spacing of the Au nanoparticles is 0.2 nm - 0.3 nm.

[0008] The preparation method of the above Au-N-Ti 3 C 2 T x gas-sensitive material includes the following steps:

[0009] S1. Add Ti 3 AlC 2 to hydrofluoric acid, stir and process at 40 °C for 20 h - 28 h using a water bath, and obtain a product with a pH of 7 after centrifugation; dry the above product to obtain Ti 3 C 2 T x gas-sensitive material;

[0010] S2. Add thiourea and Ti 3 C 2 T xis added to deionized water and stirred thoroughly; then it is placed in a high-pressure reactor and treated at 160 °C - 200 °C for 10 h - 15 h, and after centrifugal drying treatment, N-Ti 3 C 2 T x gas-sensitive material;

[0011] S3. Dissolve sodium citrate in deionized water and ultrasonically dissolve it to obtain an aqueous sodium citrate solution;

[0012] Dissolve AuCl 3 ·HCl·4H 2 O in deionized water and stir at 90 °C for 30 min to obtain an AuCl 3 ·HCl·4H 2 O solution;

[0013] Pour the aqueous sodium citrate solution into the AuCl 3 ·HCl·4H 2 O solution, stir at 97 °C at 3500 rpm for 30 min, and then obtain a gold nanoparticle solution;

[0014] S4. Add N-Ti 3 C 2 T x to deionized water to obtain an N-Ti 3 C 2 T x solution, and dropwise add the gold nanoparticle solution to obtain a mixture; then place the mixture in a high-pressure reactor and treat it at 110 °C - 130 °C for 7 h - 9 h, and after centrifugal drying treatment, obtain Au-N-Ti 3 C 2 T x gas-sensitive material.

[0015] Preferably, in the S1, the mass concentration of hydrofluoric acid is 33%, and the mass ratio of Ti 3 AlC 2 to hydrofluoric acid is 1:5 - 7; the drying treatment is drying under vacuum at 60 °C.

[0016] Preferably, in the S2, the mass ratio of thiourea to Ti 3 C 2 T x is 1 - 7:10.

[0017] Preferably, in the S3, the mass concentration of the aqueous sodium citrate solution is 0.2 g / L - 0.3 g / L, and the mass concentration of the AuCl 3 ·HCl·4H 2 O solution is 0.02 g / mL,

[0018] Preferably, in S3, the particle size of the gold nanoparticles in the gold nanoparticle solution is 6 nm - 8 nm.

[0019] Preferably, in S4, the mass concentration of the N-Ti 3 C 2 T x solution is 1.25 g / L, and the volume ratio of the gold nanoparticle solution to deionized water is 1 - 5:40.

[0020] Add the Au-N-Ti 3 C 2 T x gas-sensitive material to deionized water and grind it for 10 min. The mass concentration of the Au-N-Ti 3 C 2 T x gas-sensitive material is 2 g / L. Drop the ground product onto the Ag-Pd interdigital electrode to obtain a gas sensor.

[0021] The gas sensor is applied in NH 3 gas detection at room temperature.

[0022] The Au-N-Ti 3 C 2 T x gas-sensitive material and its preparation method and application have the following advantages and positive effects:

[0023] 1. In the Au-N-Ti 3 C 2 T x gas-sensitive material of the present invention, N atom doping and loading of Au nanoparticles are carried out to achieve lattice dislocation of Ti 3 C 2 T x and increase the active sites; and a Schottky barrier is formed, increasing the resistance and the sensitivity; the particle effect of the noble metal Au increases the catalytic activity of Ti 3 C 2 Tx, which can effectively improve the response speed and recovery speed of the sensor and has high stability, solving the problem of the drift of the resistance baseline value of Ti 3 C 2 Tx.

[0024] 2. The gas sensor prepared with the gas-sensitive material of the present invention can achieve efficient detection of NH 3 at room temperature, and has the advantages of fast response speed, fast recovery speed and high stability.

[0025] 3. The preparation method of the gas-sensitive material of the present invention is simple, easy to operate and environmentally friendly.

[0026] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Description of the Drawings

[0027] Figure 1 It is a flowchart of an embodiment of the present invention;

[0028] Figure 2 It is the SEM image and HRTEM image of the present invention; (a) and (b) are the SEM images of Ti 3 C 2 T x in Comparative Example 1, (c) and (d) are the SEM images of Au2-N4-Ti 3 C 2 T x in Example 2, (e) and (f) are the HRTEM images of Au2-N4-Ti 3 C 2 T x in Example 2;

[0029] Figure 3 It is the response values of the gas sensors prepared in Examples 1-3 and Comparative Examples 1-5 of the present invention to each gas at 100 ppm at room temperature;

[0030] Figure 4 It is the response curve of the Ti 3 C 2 T x gas sensor prepared in Comparative Example 1 of the present invention to 100 ppm of NH 3 ;

[0031] Figure 5 It is the response curves of the TC-N1, TC-N2, TC-N3, and TC-N4 gas sensors prepared in Comparative Examples 2-5 of the present invention to 100 ppm of NH 3 ;

[0032] Figure 6 It is the response curves of the TC-N4-Au1, TC-N4-Au2, and TC-N4-Au3 gas sensors prepared in Examples 1-3 of the present invention to 100 ppm of NH 3 ;

[0033] Figure 7 It is the response time and recovery time of the Ti 3 C 2 T x 、TC-N4, and TC-N4-Au2 gas sensors prepared in Comparative Example 1, Comparative Example 5, and Example 2 of the present invention in 100 ppm of NH 3 ;

[0034] Figure 8 Response of the TC-N4-Au2 gas sensor prepared in Example 2 of the present invention to NH3 in the range of 1 ppm - 100 ppm 3 in it. Detailed implementation manners

[0035] In this application, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. In case of inconsistency, the meaning described in this specification or the meaning obtained according to the content recorded in this specification shall prevail. Additionally, the terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application. For the purpose of accurately describing the technical content in this application and for accurately understanding the present invention, the following explanatory notes or definitions are given for the terms used in this specification before explaining the specific implementation manners:

[0036] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0037] As Figure 1 shown. A Au-N-Ti 3 C 2 T x gas-sensitive material, the chemical formula of the gas-sensitive material is Au a -N b -Ti 3 C 2 T x , where 1 ≤ a ≤ 3 and 1 ≤ b ≤ 4. The structure of the gas-sensitive material is that lamellar Au nanoparticles are loaded on a two-dimensional accordion-shaped Ti 3 C 2 T x nanosheet.

[0038] Ti 3 C 2 T x The interlayer spacing of the nanosheet is 0.2 nm - 0.3 nm. The particle size of the Au nanoparticles is 6 nm - 8 nm, and the inter-sheet spacing of the Au nanoparticles is 0.2 nm - 0.3 nm.

[0039] In the present invention, the -OH groups on the surface of Ti 3 C 2 T x have the strongest binding energy to NH 3 , so that NH 3 molecules will not detach from the Ti 3 C 2 T xThe surface is completely desorbed, resulting in the problem of resistance baseline drift in the sensor. Through N atom doping, the surface -OH groups are replaced by N atoms, and the N atoms are absorbed through the -O end, resulting in N-Ti 3 C 2 T x The content of -OH and -O ends on the surface is less, making Ti 3 C 2 T x layer oxidation reduced. This promotes the desorption process of NH 3 and solves the problem of resistance baseline value drift of Ti 3 C 2 T x and makes the sensor exhibit high stability. In addition, N atoms can also replace the carbon atoms in Ti 3 C 2 T x to cause lattice dislocation of N-Ti 3 C 2 T x and increase the active sites, thereby enhancing the adsorption capacity of N-Ti 3 C 2 T x for NH 3 and making the sensor highly selective to NH 3 .

[0040] By loading Au nanoparticles, the quantum size effect of Au nanoparticles and their high catalytic activity are used to increase the interaction between NH 3 molecules and the sensing layer, and promote the dissociation and diffusion of NH 3 , thereby improving the response speed and recovery speed of the sensor. In addition, the work functions of Au and Ti 3 C 2 T x are different. When in contact, electrons move from Ti 3 C 2 T x to Au, making the Fermi levels equal to form a Schottky barrier. Due to the flow of electrons, relative to the original Ti 3 C 2 T x , the depletion layer width inside Au-N-Ti 3 C 2 T x increases. NH 3 gas acts as an electron donor. When it comes into contact with NH 3 gas, electrons return to the surface of the sensing layer, resulting in a significant change in the resistance of the gas sensor and thus improving the response of the sensor.

[0041] The above Au-N-Ti3 C 2 T x Preparation method of gas-sensitive material, comprising the following steps:

[0042] S1. Add Ti 3 AlC 2 to hydrofluoric acid, stir and process at 40 °C for 20 h - 28 h using a water bath, and obtain a product with a pH of 7 after centrifugation; dry the above product to obtain Ti 3 C 2 T x gas-sensitive material.

[0043] The mass concentration of hydrofluoric acid is 33%, and the mass ratio of Ti 3 AlC 2 to hydrofluoric acid is 1:5 - 7; the drying treatment is drying under vacuum at 60 °C.

[0044] S2. Add thiourea and Ti 3 C 2 T x to deionized water and stir well; then place it in a high-pressure reactor and process at 160 °C - 200 °C for 10 h - 15 h, and obtain N-Ti 3 C 2 T x gas-sensitive material after centrifugation and drying.

[0045] The mass ratio of thiourea and Ti 3 C 2 T x is 1 - 7:10.

[0046] S3. Dissolve sodium citrate in deionized water and ultrasonically dissolve it to obtain an aqueous sodium citrate solution;

[0047] Dissolve AuCl 3 ·HCl·4H 2 O in deionized water, stir at 90 °C for 30 min to obtain an AuCl 3 ·HCl·4H 2 O solution;

[0048] Pour the aqueous sodium citrate solution into the AuCl 3 ·HCl·4H 2 O solution, stir at 97 °C at 3500 rpm for 30 min, and obtain a gold nanoparticle solution.

[0049] The mass concentration of the aqueous sodium citrate solution is 0.02% - 0.03%, and the mass concentration of the AuCl 3 ·HCl·4H 2 O solution is 0.02 g / mL.

[0050] The particle size of the gold nanoparticles in the gold nanoparticle solution is 6 nm - 8 nm.

[0051] S4. Add N-Ti 3 C 2 T x to deionized water to obtain an N-Ti 3 C 2 T x solution, and then dropwise add the gold nanoparticle solution to obtain a mixture; subsequently, place the mixture in a high-pressure reaction kettle and treat it at 110°C - 130°C for 7 h - 9 h, and after centrifugal drying treatment, obtain Au-N-Ti 3 C 2 T x gas-sensitive material.

[0052] The mass concentration of the N-Ti 3 C 2 T x solution is 1.25 g / L, and the volume ratio of the gold nanoparticle solution to deionized water is 1 - 5:40.

[0053] Example 1

[0054] Preparation method of Au1-N4-Ti 3 C 2 T x gas-sensitive material, comprising the following steps:

[0055] S1. Add 1 g of Ti 3 AlC 2 to 20 mL of hydrofluoric acid with a mass concentration of 33%, stir and treat it at 40°C using a water bath for 24 h, and after multiple centrifugation treatments, obtain a product with a pH of 7; dry the above product under vacuum at 60°C to obtain Ti 3 C 2 T x gas-sensitive material.

[0056] S2. Add thiourea with a mass ratio of 70% and Ti 3 C 2 T x to 40 mL of deionized water and stir well; then place it in a high-pressure reaction kettle and treat it at 180°C for 12 h, and after multiple centrifugations and drying, obtain N4-Ti 3 C 2 T x gas-sensitive material.

[0057] S3. Dissolve 0.007 g of sodium citrate in 25 mL of deionized water and ultrasonically dissolve it to obtain an aqueous sodium citrate solution;

[0058] Dissolve 30 μL of AuCl 3 ·HCl·4H 2 O in 25 mL of deionized water, stir at 90 °C for 30 min to obtain an AuCl 3 ·HCl·4H 2 O solution;

[0059] Pour the aqueous sodium citrate solution into the AuCl 3 ·HCl·4H 2 O solution, stir at 3500 rpm at 97 °C for 30 min, and then obtain a gold nanoparticle solution.

[0060] S4. Add 50 mg of N4-Ti 3 C 2 T x to 40 mL of deionized water to obtain an N4-Ti 3 C 2 T x solution, and add 1 mL of the gold nanoparticle solution to obtain a mixture; then place the mixture in a high-pressure reactor, treat it at 120 °C for 8 h, and after centrifugation and drying for several times, obtain an Au1-N4-Ti 3 C 2 T x gas-sensitive material.

[0061] Example 2

[0062] Preparation method of Au2-N4-Ti 3 C 2 T x gas-sensitive material, comprising the following steps:

[0063] S1. Add 1 g of Ti 3 AlC 2 to 20 mL of hydrofluoric acid with a mass concentration of 33%, stir and treat it at 40 °C using a water bath for 24 h, and after centrifugation for several times, obtain a product with a pH of 7; dry the above product under vacuum at 60 °C to obtain Ti 3 C 2 T x gas-sensitive material.

[0064] S2. Add thiourea with a mass ratio of 70% and Ti 3 C 2 T x to 40 mL of deionized water and stir well; then place it in a high-pressure reactor, treat it at 180 °C for 12 h, and after centrifugation and drying for several times, obtain N4-Ti 3 C 2 T x gas-sensitive material.

[0065] S3. Dissolve 0.007 g of sodium citrate in 25 mL of deionized water and ultrasonically dissolve it to obtain an aqueous sodium citrate solution;

[0066] Dissolve 30 μL of AuCl 3 ·HCl·4H 2 O in 25 mL of deionized water, stir at 90 °C for 30 min to obtain an AuCl 3 ·HCl·4H 2 O solution;

[0067] Pour the aqueous sodium citrate solution into the AuCl 3 ·HCl·4H 2 O solution, stir at 97 °C at 3500 rpm for 30 min, and then obtain a gold nanoparticle solution.

[0068] S4. Add 50 mg of N4-Ti 3 C 2 T x to 40 mL of deionized water to obtain an N4-Ti 3 C 2 T x solution, and add 3 mL of the gold nanoparticle solution to obtain a mixture; then place the mixture in a high-pressure reaction kettle, treat it at 120 °C for 8 h, and after centrifugation and drying for multiple times, obtain an Au2-N4-Ti 3 C 2 T x gas-sensitive material.

[0069] Example 3

[0070] A preparation method of Au3-N4-Ti 3 C 2 T x gas-sensitive material, comprising the following steps:

[0071] S1. Add 1 g of Ti 3 AlC 2 to 20 mL of hydrofluoric acid with a mass concentration of 33%, stir and treat it at 40 °C using a water bath for 24 h, and after centrifugation for multiple times, obtain a product with a pH of 7; dry the above product under vacuum at 60 °C to obtain Ti 3 C 2 T x gas-sensitive material.

[0072] S2. Mix 70% by mass of thiourea and Ti 3 C 2 T xwas added to 40 mL of deionized water and stirred thoroughly; then it was placed in a high-pressure reactor and treated at 180 °C for 12 h. After centrifugation several times and drying, N4-Ti 3 C 2 T x gas-sensitive material was obtained.

[0073] S3. Dissolve 0.007 g of sodium citrate in 25 mL of deionized water and ultrasonically dissolve it to obtain an aqueous sodium citrate solution;

[0074] Pour 30 μL of AuCl 3 ·HCl·4H 2 O into 25 mL of deionized water and stir at 90 °C for 30 min to obtain an AuCl 3 ·HCl·4H 2 O solution;

[0075] Pour the aqueous sodium citrate solution into the AuCl 3 ·HCl·4H 2 O solution, stir at 97 °C at 3500 rpm for 30 min, and then obtain a gold nanoparticle solution.

[0076] S4. Add 50 mg of N4-Ti 3 C 2 T x to 40 mL of deionized water to obtain an N4-Ti 3 C 2 T x solution, and add 5 mL of the gold nanoparticle solution to obtain a mixture; then place the mixture in a high-pressure reactor and treat it at 120 °C for 8 h. After centrifugation several times and drying, Au3-N4-Ti 3 C 2 T x gas-sensitive material was obtained.

[0077] Example 4

[0078] Preparation method of Au2-N1-Ti 3 C 2 T x gas-sensitive material, comprising the following steps:

[0079] S1. Add 1 g of Ti 3 AlC 2 to 20 mL of hydrofluoric acid with a mass concentration of 33%, stir and treat it at 40 °C using a water bath for 24 h, and after centrifugation several times, obtain a product with a pH of 7; dry the above product under vacuum at 60 °C to obtain Ti 3 C 2 T x gas-sensitive material.

[0080] S2. Add thiourea with a mass ratio of 10% and Ti 3 C 2 T x to 40 mL of deionized water and stir well; then place it in a high-pressure reactor and treat it at 180 °C for 12 h. After centrifuging multiple times and drying, N1-Ti 3 C 2 T x gas-sensitive material is obtained.

[0081] S3. Dissolve 0.007 g of sodium citrate in 25 mL of deionized water and ultrasonically dissolve it to obtain an aqueous sodium citrate solution;

[0082] Dissolve 30 μL of AuCl 3 ·HCl·4H 2 O in 25 mL of deionized water and stir at 90 °C for 30 min to obtain an AuCl 3 ·HCl·4H 2 O solution;

[0083] Pour the aqueous sodium citrate solution into the AuCl 3 ·HCl·4H 2 O solution, and stir at 97 °C at 3500 rpm for 30 min to obtain a gold nanoparticle solution.

[0084] S4. Add 50 mg of N1-Ti 3 C 2 T x to 40 mL of deionized water to obtain an N1-Ti 3 C 2 T x solution, and add 3 mL of the gold nanoparticle solution to obtain a mixture; then place the mixture in a high-pressure reactor and treat it at 120 °C for 8 h. After centrifuging multiple times and drying, Au2-N1-Ti 3 C 2 T x gas-sensitive material is obtained.

[0085] Example 5

[0086] Preparation method of Au2-N2-Ti 3 C 2 T x gas-sensitive material, comprising the following steps:

[0087] S1. Add 1 g of Ti 3 AlC 2It was added to 20 mL of hydrofluoric acid with a mass concentration of 33%, and stirred at 40 °C for 24 h using a water bath. After multiple centrifugation treatments, a product with a pH of 7 was obtained; the above product was dried under vacuum at 60 °C to obtain Ti 3 C 2 T x gas-sensitive material.

[0088] S2. 30% by mass of thiourea and Ti 3 C 2 T x were added to 40 mL of deionized water and stirred thoroughly; then it was placed in a high-pressure reactor and treated at 180 °C for 12 h. After multiple centrifugations and drying, N2-Ti 3 C 2 T x gas-sensitive material was obtained.

[0089] S3. 0.007 g of sodium citrate was dissolved in 25 mL of deionized water and ultrasonicated to dissolve it completely to obtain an aqueous sodium citrate solution;

[0090] 30 μL of AuCl 3 ·HCl·4H 2 O was dissolved in 25 mL of deionized water and stirred at 90 °C for 30 min to obtain an AuCl 3 ·HCl·4H 2 O solution;

[0091] The aqueous sodium citrate solution was poured into the AuCl 3 ·HCl·4H 2 O solution, and stirred at 97 °C at 3500 rpm for 30 min to obtain a gold nanoparticle solution.

[0092] S4. 50 mg of N2-Ti 3 C 2 T x was added to 40 mL of deionized water to obtain an N2-Ti 3 C 2 T x solution, and 3 mL of the gold nanoparticle solution was added dropwise to obtain a mixture; then the mixture was placed in a high-pressure reactor and treated at 120 °C for 8 h. After multiple centrifugations and drying, Au2-N2-Ti 3 C 2 T x gas-sensitive material was obtained.

[0093] Example 6

[0094] Au2-N3-Ti 3 C 2 T xPreparation method of gas-sensitive material, comprising the following steps:

[0095] S1. Add 1 g of Ti 3 AlC 2 to 20 mL of hydrofluoric acid with a mass concentration of 33%, stir and process at 40 °C for 24 h using a water bath, and after multiple centrifugation treatments, obtain a product with a pH of 7; dry the above product under vacuum at 60 °C to obtain Ti 3 C 2 T x gas-sensitive material.

[0096] S2. Add thiourea with a mass ratio of 50% and Ti 3 C 2 T x to 40 mL of deionized water and stir well; then place it in a high-pressure reaction kettle and process at 180 °C for 12 h, and after multiple centrifugations and drying, obtain N3-Ti 3 C 2 T x gas-sensitive material.

[0097] S3. Dissolve 0.007 g of sodium citrate in 25 mL of deionized water and ultrasonically dissolve it to obtain an aqueous sodium citrate solution;

[0098] Dissolve 30 μL of AuCl 3 ·HCl·4H 2 O in 25 mL of deionized water and stir at 90 °C for 30 min to obtain an AuCl 3 ·HCl·4H 2 O solution;

[0099] Pour the aqueous sodium citrate solution into the AuCl 3 ·HCl·4H 2 O solution, stir at 97 °C at 3500 rpm for 30 min, and then obtain a gold nanoparticle solution.

[0100] S4. Add 50 mg of N3-Ti 3 C 2 T x to 40 mL of deionized water to obtain an N3-Ti 3 C 2 T x solution, and dropwise add 3 mL of the gold nanoparticle solution to obtain a mixed solution; then place the mixed solution in a high-pressure reaction kettle and process at 120 °C for 8 h, and after multiple centrifugations and drying treatments, obtain Au2-N3-Ti 3 C 2 T x gas-sensitive material.

[0101] Comparative Example 1

[0102] The difference between this comparative example and Example 1 is that this comparative example only goes through Step S1 to obtain Ti 3 C 2 T x gas-sensitive material.

[0103] Comparative Example 2

[0104] The difference between this comparative example and Example 4 is that this comparative example only goes through Step S1 to obtain N1-Ti 3 C 2 T x gas-sensitive material.

[0105] Comparative Example 3

[0106] The difference between this comparative example and Example 5 is that this comparative example only goes through Steps S1 and S2 to obtain N2-Ti 3 C 2 T x gas-sensitive material.

[0107] Comparative Example 4

[0108] The difference between this comparative example and Example 6 is that this comparative example only goes through Steps S1 and S2 to obtain N3-Ti 3 C 2 T x gas-sensitive material.

[0109] Comparative Example 5

[0110] The difference between this comparative example and Example 1 is that this comparative example only goes through Steps S1 and S2 to obtain N4-Ti 3 C 2 T x gas-sensitive material.

[0111] Figure 2 are the SEM image and HRTEM image of the present invention; (a) and (b) are the SEM images of Ti 3 C 2 T x in Comparative Example 1, and (c) and (d) are the SEM images of Au2-N4-Ti 3 C 2 T x in Example 2, and (e) and (f) are the HRTEM images of Au2-N4-Ti 3 C 2 T x in Example 2. As Figure 2 shown, Au2-N4-Ti 3 C 2 Tx Ti in the gas-sensitive material 3 C 2 T x is a two-dimensional accordion-shaped nanosheet, and the sheet spacings in different orientations are 0.235 nm and 0.254 nm. On the Ti 3 C 2 T x sheet layer, AuNPs are attached. The particle size of the AuNPs is 6 nm - 8 nm, and the gold nanoparticles have a sheet-like structure with a layer spacing of 0.23 nm.

[0112] The gas-sensitive materials obtained in Examples 1 - 6 and Comparative Examples 1 - 5 were added to deionized water and ground, and the ground product was drop-coated on an Ag-Pd interdigital electrode to obtain Ti 3 C 2 T x , TC-N1, TC-N2, TC-N3, TC-N4, TC-N4-Au1, TC-N4-Au2, TC-N4-Au3 gas sensors.

[0113] Each gas sensor was placed in 100 ppm of methanol, formaldehyde, acetone, ethanol, hydrogen peroxide, toluene, NO 2 and NH 3 gases for detection at room temperature.

[0114] Figure 3 This is the response value of the gas sensors prepared in Examples 1 - 3 and Comparative Examples 1 - 5 of the present invention in 100 ppm of each gas at room temperature. As Figure 3 shown, the TC-N4-Au1, TC-N4-Au2, TC-N4-Au3 gas sensors described in Examples 1 - 3 have a relatively high response value to NH 3 , indicating that the gas sensors prepared with the gas-sensitive material described in the present invention have high selectivity for detecting NH 3 at room temperature.

[0115] Figure 4 This is the response curve of the Ti 3 C 2 T x gas sensor prepared in Comparative Example 1 of the present invention to 100 ppm of NH 3 , Figure 5 This is the response curve of the TC-N1, TC-N2, TC-N3, TC-N4 gas sensors prepared in Comparative Examples 2 - 5 of the present invention to 100 ppm of NH 3 ; Figure 6 This is the response curve of the TC-N4-Au1, TC-N4-Au2, TC-N4-Au3 gas sensors prepared in Examples 1 - 3 of the present invention to 100 ppm of NH 3Response curve. By comparing Figure 4 , Figure 5 and Figure 6 , it can be seen that the TC-N4-Au1, TC-N4-Au2, and TC-N4-Au3 gas sensors prepared in Examples 1-3 have better detection performance and stability for 100 ppm of NH 3 , and solve the problem of resistance baseline value drift.

[0116] Figure 7 This is the response time and recovery time of the Ti 3 C 2 T x , TC-N4, and TC-N4-Au2 gas sensors prepared in Comparative Example 1, Comparative Example 5, and Example 2 of the present invention in 100 ppm of NH 3 . As can be seen from Figure 7 , the response time of the Ti 3 C 2 T x gas sensor for detecting 100 ppm of NH 3 is 17 s, and the recovery time is 13 s; the response time of the TC-N4 gas sensor in Comparative Example 5 for detecting 100 ppm of NH 3 is 13 s, and the recovery time is 16 s; the response time of the TC-N4-Au2 gas sensor in Example 2 for detecting 100 ppm of NH 3 is 9 s, and the recovery time is 8 s; it can be seen that the gas sensor described in this claim has shorter detection response time and recovery time for detecting 100 ppm of NH 3 , and the detection speed is higher.

[0117] Figure 8 This is the response of the TC-N4-Au2 gas sensor prepared in Example 2 of the present invention in 1 ppm - 100 ppm of NH 3 . As shown in Figure 8 , the TC-N4-Au2 gas sensor has good detection response to 1 ppm - 100 ppm of NH 3 , and as the concentration of NH 3 increases, the detection response increases linearly.

[0118] Therefore, by using the Au-N-Ti 3 C 2 T x gas sensitive material and its preparation method and application of the present invention, using Au nanoparticle loading, N atom doping, and constructing a composite material with the Ti 3 C 2 T x gas sensitive material, the composite material is realized with Ti 3 C2 T x Lattice dislocation, formation of Schottky barriers, and the catalytic effect of noble metals solve the problems of low sensor response, poor stability, and drift of the resistance baseline value; high-selectivity detection of NH 3 is achieved at room temperature.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. Au-N-Ti3C2T x Gas-sensitive material, characterized in that: The chemical formula of the gas-sensitive material is Au a -N b -Ti3C2T x , where 1≤a≤3, 1≤b≤4; the structure of the gas-sensitive material is a two-dimensional accordion-shaped Ti3C2T x The nanosheets are loaded with lamellar Au nanoparticles.

2. The Au-N-Ti3C2T3 according to claim 1 x Gas-sensitive material, characterized in that: The Ti3C2T x The interlayer spacing of the nanosheets is 0.2nm-0.3nm; the particle size of the Au nanoparticles is 6nm-8nm, and the interlayer spacing of the Au nanoparticles is 0.2nm-0.3nm.

3. An Au-N-Ti3C2T3 as claimed in claim 1 or 2 x A method for preparing a gas-sensitive material, characterized in that: The following steps are involved: S1. Add Ti3AlC2 to hydrofluoric acid, stir in a water bath at 40°C for 20-28h, and centrifuge to obtain a product with a pH of 7; dry the product to obtain Ti3C2T x Gas sensitive materials; S2, thiourea and Ti3C2T x The mixture was added to deionized water and stirred thoroughly; then placed in a high pressure reactor, treated at 160℃-200℃ for 10h-15h, and centrifuged to obtain N-Ti3C2T x Gas sensitive materials; S3, dissolving sodium citrate in deionized water by ultrasonication to fully dissolve it, to obtain a sodium citrate aqueous solution; AuCl3·HCl·4H2O was dissolved in deionized water and stirred at 90°C for 30 min to obtain AuCl3·HCl·4H2O solution; The sodium citrate aqueous solution was poured into the AuCl3·HCl·4H2O solution and stirred at 3500 rpm for 30 min at 97°C to obtain a gold nanoparticle solution; S4, N-Ti3C2T x Add to deionized water to obtain N-Ti3C2T x The solution was added dropwise with a gold nanoparticle solution to obtain a mixed solution; the mixed solution was then placed in a high pressure reactor, treated at 110°C-130°C for 7h-9h, and centrifuged to obtain Au-N-Ti3C2T x Gas sensitive materials.

4. The Au-N-Ti3C2T3 according to claim 3 x The method for preparing a gas-sensitive material is characterized by: In the S1, the mass concentration of hydrofluoric acid is 33%, and the mass ratio of Ti3AlC2 to hydrofluoric acid is 1:5-7; the drying treatment is drying at 60°C under vacuum conditions.

5. The Au-N-Ti3C2T3 according to claim 3 x The method for preparing a gas-sensitive material is characterized by: The S2, thiourea and Ti3C2T x The mass ratio is 1-7:

10.

6. The Au-N-Ti3C2T3 according to claim 3 x The method for preparing a gas-sensitive material is characterized by: In S3, the mass concentration of the sodium citrate aqueous solution is 0.2 g / L-0.3 g / L, and the mass concentration of the AuCl3·HCl·4H2O solution is 0.02 g / mL.

7. The Au-N-Ti3C2T3 according to claim 3 x The method for preparing a gas-sensitive material is characterized by: In S3, the particle size of the gold nanoparticles in the gold nanoparticle solution is 6nm-8nm.

8. The Au-N-Ti3C2T3 according to claim 3 x The method for preparing a gas-sensitive material is characterized by: The S4, N-Ti3C2T x The mass concentration of the solution is 1.25 g / L, and the volume ratio of the gold nanoparticle solution to deionized water is 1-5:

40.

9. An Au-N-Ti3C2T3 according to claim 1 or 2 x The application of gas-sensitive materials is characterized by: Au-N-Ti3C2T x The gas-sensitive material was added to deionized water and ground for 10 min. x The mass concentration of the gas-sensitive material is 2 g / L. The ground product is drop-coated on the Ag-Pd interdigital electrode to obtain a gas sensor. The gas sensor is used in NH3 gas detection at room temperature.

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