A MXene@Au self-healing hydrogel gas-sensitive material, gas-sensitive element, gas sensor, preparation method and application thereof

Abstract

The invention relates to the technical field of gas sensors, and in particular to a MXene@Au self-healing hydrogel gas-sensitive material, a gas-sensitive element, a gas sensor, a preparation method and an application thereof. PVA is dissolved in ultrapure water at 95°C, and then a MXene@Au composite material dispersion is added, and a tannic acid solution is added after stirring and dispersing, and stirring is continued to allow the tannic acid and the PVA to react completely, and the PVA / MXene@Au self-healing hydrogel is taken out after soaking for 30 minutes to obtain the PVA / MXene@Au self-healing hydrogel; then the self-healing hydrogel is pressed into a suitable shape in a mold, and finally the obtained PVA / MXene@Au self-healing hydrogel is connected in series with a fixed resistor and two dry batteries to form a closed loop, and a voltmeter is connected and connected in parallel with the fixed resistor to obtain the PVA / MXene@Au self-healing hydrogel gas sensor, which solves the problems that the MXene material has a high resistivity at room temperature and has a poor gas response, and the traditional gas sensor has a poor mechanical property. The prepared gas sensor has certain mechanical properties, good self-healing performance, high selectivity, and good responsiveness to trimethylamine gas.

Description

Technical Field

[0001] The present invention relates to the technical field of gas sensors, and in particular to a MXene@Au self-healing hydrogel gas-sensitive material, a gas-sensitive element, a gas sensor, a preparation method and applications thereof. Background Art

[0002] As an effective method for detecting toxic gases in the environment, gas sensors are becoming increasingly important in preventing human health problems caused by toxic gas pollution in the environment. Among the common toxic gases, trimethylamine is extremely harmful to the human body. Excessive concentrations of trimethylamine gas can irritate people's eyes, cause headaches, breathing difficulties, lung infections, and even cause death in severe cases. Trimethylamine gas is a relatively common gas in human daily life. It is usually produced during the corruption of meat. Therefore, the concentration of trimethylamine can also be used to judge the freshness of food. For this reason, detecting the concentration of trimethylamine gas in the environment is of great significance for preventing poisoning caused by excessive concentration of trimethylamine gas and protecting human life and health safety.

[0003] Polyvinyl alcohol (PVA) is a relatively safe polymer material that is non-toxic, odorless and pollution-free. PVA has the advantages of good biocompatibility with the human body, easy film formation and good mechanical properties, making it an ideal material for hydrogels.

[0004] MXene is a new type of semiconductor material with the advantages of large specific surface area and rich surface functional groups, which provide abundant active sites for the adsorption of gas molecules. However, its high resistivity at room temperature and easy cracking after drying are not conducive to its application in gas sensors.

[0005] In view of the above-mentioned defects, the inventors of the present invention finally obtained the present invention after a long period of research and practice. Summary of the invention

[0006] The purpose of the present invention is to solve the problem of how to use the self-healing hydrogel prepared from the MXene@Au composite material for gas sensing, and provide a MXene@Au self-healing hydrogel gas-sensitive material, a gas-sensitive element, a gas sensor, a preparation method and applications thereof.

[0007] In order to achieve the above object, the present invention discloses a method for preparing a MXene@Au self-healing hydrogel, comprising the following steps:

[0008] S1: Preparation of MXene@Au composite material: Take 0-3 parts by volume of MXene dispersion, add 0-3 parts of HAuCl4·XH2O solution into the MXene dispersion and stir for 30 minutes to obtain the final product MXene@Au composite material;

[0009] S2: Preparation of MXene@Au self-healing hydrogel: Take 0 to 2.5 parts by volume of MXene@Au composite material and add it to 6.66 parts of PVA solution. After stirring, add ultrapure water to 10 parts. Continue to stir evenly and then add 20 mL of tannic acid solution. After the reaction is complete, soak for 30 minutes to obtain MXene@Au self-healing hydrogel.

[0010] In step S1, the concentration of the MXene dispersion is 10 mg / mL, the concentration of the HAuCl4·XH2O solution is 10 mg / mL, the solvent for preparing the HAuCl4·XH2O solution is ultrapure water, and the HAuCl4·XH2O solution needs to be stored at low temperature and away from light.

[0011] The mass fraction of the PVA solution in step S2 is 12%, the concentration of the tannic acid solution is 0.05 mg / mL to 0.25 mg / mL, the solvent for preparing the PVA solution is ultrapure water, and the dissolution conditions are condensing, refluxing, stirring and dissolving in a 95° C. water bath for 3 hours.

[0012] The preparation conditions of the tannic acid solution in step S2 are as follows: adding tannic acid to ultrapure water and ultrasonically dispersing at 800W until the tannic acid is completely dissolved.

[0013] The present invention also discloses a MXene@Au self-healing hydrogel prepared by the preparation method.

[0014] The present invention also discloses a method for preparing a gas sensor using the MXene@Au self-healing hydrogel, comprising the following processes: cutting the MXene@Au self-healing hydrogel into a size that meets the requirements, and preparing the gas sensor by this method.

[0015] The present invention also discloses a method for preparing a gas sensor using the MXene@Au self-healing hydrogel, comprising the following process: connecting the MXene@Au self-healing hydrogel, a 12kΩ fixed resistor and two dry batteries in series to form a closed loop, connecting a voltmeter and connecting the voltmeter in parallel with the fixed resistor to obtain a MXene@Au self-healing hydrogel gas sensor, as well as a gas sensor prepared by this method, and application of the gas sensor in detecting trimethylamine gas concentration.

[0016] When MXene is exposed to air, the O2 adsorbed on its surface will obtain electrons from MXene to form a layer of oxygen anions on the surface of MXene. In this process, the MXene@Au self-healing hydrogel loses electrons, resulting in a decrease in the concentration of carriers in the MXene@Au self-healing hydrogel. The resistivity of the hydrogel will continue to increase until the process of forming oxygen anions balances the electron loss of MXene. When the MXene@Au self-healing hydrogel is exposed to trimethylamine gas, the trimethylamine gas will first be adsorbed on MXene due to the concentration difference and because MXene has a large specific surface area and rich surface functional groups. After that, the trimethylamine gas molecules will chemically react with the oxygen anions on the surface of MXene and release electrons to MXene. Since this process releases electrons to the MXene material, the carrier concentration of the MXene@Au self-healing hydrogel will increase. Therefore, the resistivity of the MXene@Au self-healing hydrogel will decrease during this process.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: the preparation process of the present invention is simple, MXene and gold nanoparticles are successfully compounded by an in-situ synthesis method to obtain a MXene@Au composite material and the composite material is added to a PVA solution, and a MXene@Au self-healing hydrogel with self-healing properties is obtained by simple stirring, which is applied to a gas sensor. The prepared gas sensor has the advantages of a simple preparation method, high selectivity for trimethylamine gas, good responsiveness, detectability at room temperature, certain mechanical properties and superior self-healing properties, and has great application prospects in the direction of room temperature wearable gas sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Optical photos of the self-repairing of Comparative Example 1 and Example 1 of the present invention at room temperature and their microstructures under a scanning electron microscope;

[0019] Figure 2 Optical photos of the MXene@Au sensor in Comparative Example 6 of the present invention and test results of selectivity to different gases at 10 ppm;

[0020] Figure 3 The test results of the PVP / MXene@Au self-healing hydrogel sensor for different gases at 10 ppm in Example 2 of the present invention;

[0021] Figure 4 Response-recovery curve of the PVP / MXene@Au self-healing hydrogel sensor to trimethylamine gas of different concentrations in Example 3 of the present invention;

[0022] Figure 5The test results of the repeatability of the PVP / MXene@Au self-healing hydrogel sensor to 10ppm trimethylamine gas in Example 4 of the present invention;

[0023] Figure 6 This is the test result of the stability of the PVP / MXene@Au self-healing hydrogel sensor to 10 ppm trimethylamine gas in Example 5 of the present invention. DETAILED DESCRIPTION

[0024] The above and other technical features and advantages of the present invention are described in more detail below in conjunction with the accompanying drawings.

[0025] Comparative Example 1

[0026] Take 6.66g (10wt%) PVP solution, add ultrapure water to 10g, heat and stir until completely dissolved to obtain solution A. Take 3g tannic acid powder and dissolve it in 20mL ultrapure water, and obtain solution B after ultrasonic dissolution. Pour the prepared solution B into solution A, stir while pouring until it becomes solid, and then soak it in the solution for 30min to obtain PVP / MXene@Au self-healing hydrogel. Take the PVP / MXene@Au self-healing hydrogel out of the tannic acid solution, wipe it dry, and cut it into a 20mm*10mm*2mm cuboid. The PVP / MXene@Au self-healing hydrogel gas sensor prepared by the above preparation method is connected in series with a 12kΩ fixed resistor and 2 dry batteries to form a closed loop, connected to a voltmeter and connected in parallel with the fixed resistor to obtain the prepared gas sensor. Test its gas-sensitive performance to 10ppm trimethylamine gas.

[0027] Comparative Example 2

[0028] Take 0.33mL (10mg / mL) of MXene solution and 0.17mL (10mg / mL) and add them to 6.66g (10wt%) PVP solution, add ultrapure water to 10g, heat and stir until completely dissolved to obtain solution A. Take 3g of tannic acid powder and dissolve it in 20mL of ultrapure water, and obtain solution B after ultrasonic dissolution. Pour the prepared solution B into solution A, stir while pouring until it becomes solid, and then soak it in the solution for 30min to obtain PVP / MXene@Au self-healing hydrogel. Take the PVP / MXene@Au self-healing hydrogel out of the tannic acid solution, wipe it dry, and cut it into a 20mm*10mm*2mm cuboid. The PVP / MXene@Au self-healing hydrogel gas sensor prepared by the above preparation method is connected in series with a 12kΩ fixed resistor and 2 dry batteries to form a closed loop, connected to a voltmeter and connected in parallel with the fixed resistor to obtain the prepared gas sensor. The gas-sensing performance of the sensor to 10ppm trimethylamine gas was tested.

[0029] Comparative Example 3

[0030] Take 0.67mL (10mg / mL) of MXene solution and 0.33mL (10mg / mL) and add them to 6.66g (10wt%) PVP solution, add ultrapure water to 10g, heat and stir until completely dissolved to obtain solution A. Take 3g of tannic acid powder and dissolve it in 20mL of ultrapure water, and obtain solution B after ultrasonic dissolution. Pour the prepared solution B into solution A, stir while pouring until it becomes solid, and then soak it in the solution for 30min to obtain PVP / MXene@Au self-healing hydrogel. Take the PVP / MXene@Au self-healing hydrogel out of the tannic acid solution, wipe it dry, and cut it into a 20mm*10mm*2mm cuboid. The PVP / MXene@Au self-healing hydrogel gas sensor prepared by the above preparation method is connected in series with a 12kΩ fixed resistor and 2 dry batteries to form a closed loop, connected to a voltmeter and connected in parallel with the fixed resistor to obtain the prepared gas sensor. The gas-sensing performance of the sensor to 10ppm trimethylamine gas was tested.

[0031] Comparative Example 4

[0032] Take 1.33mL (10mg / mL) of MXene solution and 0.67mL (10mg / mL) and add them to 6.66g (10wt%) PVP solution, add ultrapure water to 10g, heat and stir until completely dissolved to obtain solution A. Take 3g of tannic acid powder and dissolve it in 20mL of ultrapure water, and obtain solution B after ultrasonic dissolution. Pour the prepared solution B into solution A, stir while pouring until it becomes solid, and then soak it in the solution for 30min to obtain PVP / MXene@Au self-healing hydrogel. Take the PVP / MXene@Au self-healing hydrogel out of the tannic acid solution, wipe it dry, and cut it into a 20mm*10mm*2mm cuboid. The PVP / MXene@Au self-healing hydrogel gas sensor prepared by the above preparation method is connected in series with a 12kΩ fixed resistor and 2 dry batteries to form a closed loop, connected to a voltmeter and connected in parallel with the fixed resistor to obtain the prepared gas sensor. The gas-sensing performance of the sensor to 10ppm trimethylamine gas was tested.

[0033] Comparative Example 5

[0034] Take 1.67mL (10mg / mL) of MXene solution and 0.83mL (10mg / mL) and add them to 6.66g (10wt%) PVP solution, add ultrapure water to 10g, heat and stir until completely dissolved to obtain solution A. Take 3g of tannic acid powder and dissolve it in 20mL of ultrapure water, and obtain solution B after ultrasonic dissolution. Pour the prepared solution B into solution A, stir while pouring until it becomes solid, and then soak it in the solution for 30min to obtain PVP / MXene@Au self-healing hydrogel. Take the PVP / MXene@Au self-healing hydrogel out of the tannic acid solution, wipe it dry, and cut it into a 20mm*10mm*2mm cuboid. The PVP / MXene@Au self-healing hydrogel gas sensor prepared by the above preparation method is connected in series with a 12kΩ fixed resistor and 2 dry batteries to form a closed loop, connected to a voltmeter and connected in parallel with the fixed resistor to obtain the prepared gas sensor. The gas-sensing performance of the sensor to 10ppm trimethylamine gas was tested.

[0035] Comparative Example 6

[0036] The MXene@Au composite material was drop-coated on the interdigital electrode and dried to obtain the MXene@Au gas sensor. The MXene@Au gas sensor prepared by the above preparation method was connected in series with a 12kΩ fixed resistor and two dry batteries to form a closed loop, connected to a voltmeter and connected in parallel with the fixed resistor to obtain the prepared gas sensor. Its gas sensing performance to 10ppm trimethylamine gas was tested.

[0037] Example 1

[0038] Take 1mL (10mg / mL) of MXene solution and 0.5mL (10mg / mL) and add them to 6.66g (10wt%) PVP solution, add ultrapure water to 10g, heat and stir until completely dissolved to obtain solution A. Take 3g of tannic acid powder and dissolve it in 20mL of ultrapure water, and obtain solution B after ultrasonic dissolution. Pour the prepared solution B into solution A, stir while pouring until it becomes solid, and then soak it in the solution for 30min to obtain PVP / MXene@Au self-healing hydrogel. Take the PVP / MXene@Au self-healing hydrogel out of the tannic acid solution, wipe it dry, and cut it into a 20mm*10mm*2mm cuboid. The PVP / MXene@Au self-healing hydrogel gas sensor prepared by the above preparation method is connected in series with a 12kΩ fixed resistor and 2 dry batteries to form a closed loop, connected to a voltmeter and connected in parallel with the fixed resistor to obtain the prepared gas sensor. The gas-sensing performance of the sensor to 10ppm trimethylamine gas was tested.

[0039] Example 2

[0040] Take 1mL (10mg / mL) of MXene solution and 0.5mL (10mg / mL) and add them to 6.66g (10wt%) PVP solution, add ultrapure water to 10g, heat and stir until completely dissolved to obtain solution A. Take 3g of tannic acid powder and dissolve it in 20mL of ultrapure water, and obtain solution B after ultrasonic dissolution. Pour the prepared solution B into solution A, stir while pouring until it becomes solid, and then soak it in the solution for 30min to obtain PVP / MXene@Au self-healing hydrogel. Take the PVP / MXene@Au self-healing hydrogel out of the tannic acid solution, wipe it dry, and cut it into a 20mm*10mm*2mm cuboid. The PVP / MXene@Au self-healing hydrogel gas sensor prepared by the above preparation method is connected in series with a 12kΩ fixed resistor and 2 dry batteries to form a closed loop, connected to a voltmeter and connected in parallel with the fixed resistor to obtain the prepared gas sensor. Test its response value to different gases at 10ppm, the results are attached Figure 2 , the PVP / MXene@Au self-healing hydrogel sensor has high selectivity for trimethylamine gas.

[0041] Example 3

[0042] Take 1mL (10mg / mL) of MXene solution and 0.5mL (10mg / mL) and add them to 6.66g (10wt%) PVP solution, add ultrapure water to 10g, heat and stir until completely dissolved to obtain solution A. Take 3g of tannic acid powder and dissolve it in 20mL of ultrapure water, and obtain solution B after ultrasonic dissolution. Pour the prepared solution B into solution A, stir while pouring until it becomes solid, and then soak it in the solution for 30min to obtain PVP / MXene@Au self-healing hydrogel. Take the PVP / MXene@Au self-healing hydrogel out of the tannic acid solution, wipe it dry, and cut it into a 20mm*10mm*2mm cuboid. The PVP / MXene@Au self-healing hydrogel gas sensor prepared by the above preparation method is connected in series with a 12kΩ fixed resistor and 2 dry batteries to form a closed loop, connected to a voltmeter and connected in parallel with the fixed resistor to obtain the prepared gas sensor. The response values ​​of the test gas to different concentrations of 1ppm, 5ppm, 10ppm, 50ppm and 100ppm are shown in the attached figure. Figure 3 , the PVP / MXene@Au self-healing hydrogel sensor has a lower detection limit for trimethylamine gas.

[0043] Example 4

[0044] Take 1mL (10mg / mL) of MXene solution and 0.5mL (10mg / mL) and add them to 6.66g (10wt%) PVP solution, add ultrapure water to 10g, heat and stir until completely dissolved to obtain solution A. Take 3g of tannic acid powder and dissolve it in 20mL of ultrapure water, and obtain solution B after ultrasonic dissolution. Pour the prepared solution B into solution A, stir while pouring until it becomes solid, and then soak it in the solution for 30min to obtain PVP / MXene@Au self-healing hydrogel. Take the PVP / MXene@Au self-healing hydrogel out of the tannic acid solution, wipe it dry, and cut it into a 20mm*10mm*2mm cuboid. The PVP / MXene@Au self-healing hydrogel gas sensor prepared by the above preparation method is connected in series with a 12kΩ fixed resistor and 2 dry batteries to form a closed loop, connected to a voltmeter and connected in parallel with the fixed resistor to obtain the prepared gas sensor. Repeatedly test its response value to 10ppm trimethylamine gas, the results are attached Figure 4 , the PVP / MXene@Au self-healing hydrogel sensor has high repeatability for trimethylamine gas.

[0045] Example 5

[0046] Take 1mL (10mg / mL) of MXene solution and 0.5mL (10mg / mL) and add them to 6.66g (10wt%) PVP solution, add ultrapure water to 10g, heat and stir until completely dissolved to obtain solution A. Take 3g of tannic acid powder and dissolve it in 20mL of ultrapure water, and obtain solution B after ultrasonic dissolution. Pour the prepared solution B into solution A, stir while pouring until it becomes solid, and then soak it in the solution for 30min to obtain PVP / MXene@Au self-healing hydrogel. Take the PVP / MXene@Au self-healing hydrogel out of the tannic acid solution, wipe it dry, and cut it into a 20mm*10mm*2mm cuboid. The PVP / MXene@Au self-healing hydrogel gas sensor prepared by the above preparation method is connected in series with a 12kΩ fixed resistor and 2 dry batteries to form a closed loop, connected to a voltmeter and connected in parallel with the fixed resistor to obtain the prepared gas sensor. The response value of the gas to 10ppm trimethylamine was tested for a long time. The results are shown in the attached Figure 5 , the PVP / MXene@Au self-healing hydrogel sensor has high stability to trimethylamine gas.

[0047] The responsiveness of the gas sensors obtained in Example 1 and Comparative Examples 2 to 5 to 10 ppm trimethylamine gas, and the effects of doping with different ratios of MXene and gold nanoparticles on the responsiveness of the composite materials are shown in Table 1 below:

[0048] Table 1 Responsiveness of composite materials with different ratios of MXene and gold nanoparticles

[0049] MXene:AuNPs Response to 10ppm trimethylamine gas Example 1 2:1 15.03 Comparative Example 2 0:1 11.67 Comparative Example 3 1:0 11.81 Comparative Example 4 1:1 13.94 Comparative Example 5 1:2 10.70

[0050] The above description is only a preferred embodiment of the present invention, which is only illustrative and not restrictive of the present invention. Those skilled in the art understand that many changes, modifications, and even equivalents may be made to the present invention within the spirit and scope defined by the claims of the present invention, but all of them will fall within the scope of protection of the present invention.

Claims

1. A MXene@Au self-healing hydrogel for preparing a gas sensor, characterized in that: The preparation method includes the following steps: connecting the MXene@Au self-healing hydrogel, a 12kΩ fixed resistor, and two dry batteries in series to form a closed loop, connecting a voltmeter and connecting in parallel with the fixed resistor to obtain a MXene@Au self-healing hydrogel gas sensor; The preparation method of the MXene@Au self-healing hydrogel comprises the following steps: S1: Preparation of MXene@Au composite material: Take 1 part by volume of MXene dispersion, add 0.5 parts of HAuCl4·XH2O solution into the MXene dispersion and stir for 30 minutes to obtain the final product MXene@Au composite material; S2: Preparation of MXene@Au self-healing hydrogel: 1.5 parts by volume of MXene@Au composite material was added to 6.66 parts of PVA solution, and ultrapure water was added to 10 parts after stirring. After continuing to stir evenly, 20 parts of tannic acid solution was added thereto. After the reaction was complete, the MXene@Au self-healing hydrogel was obtained by soaking for 30 minutes. In step S1, the concentration of the MXene dispersion is 10 mg / mL, the concentration of the HAuCl4·XH2O solution is 10 mg / mL, the solvent for preparing the HAuCl4·XH2O solution is ultrapure water, and the HAuCl4·XH2O solution needs to be stored at low temperature and away from light; The gas sensor is used in detecting the concentration of trimethylamine gas.

2. The MXene@Au self-healing hydrogel for preparing a gas sensor according to claim 1, characterized in that: The mass fraction of the PVA solution in step S2 is 12%, the concentration of the tannic acid solution is 0.05 mg / mL to 0.25 mg / mL, the solvent for preparing the PVA solution is ultrapure water, and the dissolution conditions are condensing, refluxing, stirring and dissolving in a 95° C. water bath for 3 hours.

3. The MXene@Au self-healing hydrogel for preparing a gas sensor according to claim 1, characterized in that: The preparation conditions of the tannic acid solution in step S2 are as follows: adding tannic acid to ultrapure water and ultrasonically dispersing at 800W until the tannic acid is completely dissolved.

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