CN116818850A - Novel gas sensor and preparation method thereof - Google Patents

Abstract

The invention discloses a novel gas sensor and a preparation method thereof, wherein the novel gas sensor comprises an interdigital electrode and a sensitive composite film material; the sensitive composite film material comprises an MXene material and a metal organic framework material; the MXene material is Ti ₃ C ₂ The metal organic framework material is HKUST-1. Ti in the sensitive composite film material MXene/HKUST-1 ₃ C ₂ And HKUST-1 is 1: (1.12-1.82). The gas sensor obtained by the invention has more excellent responsiveness of ammonia gas and selectivity of gas, and meanwhile, the adverse effect of water vapor on the gas sensor is small.

Description

A new type of gas sensor and its preparation method

Technical field

The invention belongs to the technical field of gas sensors, and specifically relates to a new type of gas sensor and a preparation method thereof.

Background technique

The rapid development of society and the improvement of people's living standards have also brought about environmental pollution problems. In particular, toxic and harmful gases in air pollution have always been the "killers" of people's health. Therefore, accurate detection of these toxic and harmful gases is crucial to ensuring People's physical health is of great significance. Currently commercialized resistive gas sensors based on metal oxides have high operating temperatures (200-500°C) and require heating devices during operation. Therefore, they consume large amounts of energy, are not conducive to integration, and are not suitable for flammable and explosive environments. At the same time, poor selectivity and susceptibility to humidity interference in the environment also severely limit further applications. Ammonia can affect human respiratory tract, etc. Traditional ammonia gas sensors have shortcomings such as high operating temperature, poor gas selectivity and low low-temperature conductivity. At present, the emergence of new two-dimensional materials such as reduced graphene oxide (rGO), tungsten disulfide (WS ₂ ), and molybdenum disulfide (MoS ₂ ) can help solve the above problems to a certain extent.

Contents of the invention

In view of the technical problems existing in the above prior art, the purpose of the present invention is to provide a new type of gas sensor. The gas sensor includes an interdigital electrode and a sensitive composite film material; the sensitive composite film material includes MXene material and a metal-organic material. Frame material; the MXene material is Ti ₃ C ₂ and the metal-organic framework material is HKUST-1.

Further, the composite weight ratio of Ti ₃ C ₂ and HKUST-1 in the sensitive composite film material MXene/HKUST-1 is 1: (1.12~1.82).

Another object of the present invention is to provide a preparation method of a new gas sensor, which preparation method includes the following steps:

S1: Preparation of MXene material precursor.

S2: Add the aqueous solution of copper nitrate to the MXene material precursor, then add the aqueous sodium hydroxide solution dropwise, stir magnetically at room temperature for 10 to 20 hours, add polyvinylpyrrolidone, stir and let stand.

S3: Add the methanol solution of trimesic acid to the product of step S2, stir slowly at room temperature for 2 to 3 hours, and then centrifuge. The centrifuged product is then dispersed in a mixed solution of ethanol and deionized water to obtain MXene/HKUST. -1 solution, add polydopamine and stir for 30 to 50 minutes, then spray it onto the interdigital electrode plane, and vacuum dry it at 50 to 65°C to obtain the gas sensor.

As a preferred version, the concentration of the copper nitrate aqueous solution is 15-20mM;

And/or, the concentration of the sodium hydroxide aqueous solution is 18-22mM.

As a preferred option, the preparation steps of the MXene material precursor are as follows:

(1) Disperse Ti ₃ AlC ₂ and NaOH evenly in the crucible, then move it to a quartz tube, pass in nitrogen, raise the temperature to 500-600°C, react for 30-50 hours, and then cool to room temperature.

(2) Move the above product into the reaction kettle, add deionized water, and then sonicate for 40 to 60 minutes to obtain a suspension, which is the MXene material precursor.

As a more preferred version, the molar ratio of Ti ₃ AlC ₂ and NaOH is 1:13-16.

As a more preferred version, the heating rate is 0.5-0.8°C/min.

As a preferred embodiment, the concentration of the methanol solution of trimesic acid is 0.05-0.09 mg/mL.

As a preferred embodiment, the volume ratio of the aqueous solution of copper nitrate, aqueous sodium hydroxide solution and polyvinylpyrrolidone is 1: (0.3~0.4): (0.15~0.35).

As a preferred embodiment, the volume ratio of the aqueous solution of copper nitrate and the methanol solution of trimesic acid is 1: (0.6-0.9).

As a preferred embodiment, the volume ratio of ethanol and deionized water is 1:1.2-2.

As a preferred solution, the centrifugation rate is 6000-8000r/min, and the centrifugation time is 4-8min;

And/or, the amount of polydopamine added accounts for 20% to 30% of the MXene/HKUST-1 solution.

In the present invention, the metal organic framework material HKUST and the MXene material are used to composite. The MXene material has a layered structure, and there are abundant functional groups such as hydroxyl groups, carboxyl groups, etc. between the layers, which makes the MXene material Ti ₃ C ₂ have a certain electrical property. negative, and further easily captures copper ions in water. Furthermore, after adding the methanol solution of trimesic acid, a metal organic framework material HKUST-1 with smaller grains is formed between the layered structures at room temperature, and HKUST-1 adheres Between the layers and on the surface of Ti ₃ C ₂ material.

Moreover, the metal-organic framework material in the present invention is synthesized at room temperature, which is much smaller than the particle size of the product produced by the traditional high-temperature and high-pressure synthesis method, and is easy to be compounded with MXene materials; when the sensitive composite thin film material MXene/HKUST-1 is placed in ammonia gas , since the surface of the composite material is rich in oxygen ions O ₂ ^- , the reaction between oxygen ions and ammonia causes the transfer of free electrons in the composite material, reducing the hole conductivity of the sensitive composite thin film material MXene/HKUST-1 and further increasing it. The resistance of the thin film material achieves the sensing effect. This electron transfer ability is closely related to the gas itself to be tested, so it has more sensitive sensing performance.

In addition, polydopamine is used to modify MXene/HKUST-1 to a certain extent. The phenolic hydroxyl groups in the catechol structure of polydopamine are easily combined with the functional groups in the gaps between the MXene layers and inside the pores of HKUST-1 in the form of chemical bonds, thus making the The phenolic hydroxyl group of polydopamine is not affinity with water vapor, thus reducing the impact of water vapor on the sensor.

Compared with the prior art, the present invention also has the following beneficial effects:

In the present invention, compared with the rGO composite metal-organic framework material HKUST-1 in the prior art, the gas sensing material obtained from the composite thin film material MXene/HKUST-1 has better ammonia responsivity and gas selectivity. At the same time, water vapor has less adverse effects on gas sensors.

Description of the drawings

No pictures attached.

Detailed ways

The following is a specific and detailed description of the embodiment of the present invention. This embodiment is implemented on the premise of the technical solution of the present invention, and provides detailed implementation modes and specific operating processes. It should be pointed out that for those of ordinary skill in this technical field, It is said that several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Example 1

A method for preparing a new type of gas sensor, including the following steps:

S1: Preparation of MXene material precursor.

S2: Add the aqueous solution of copper nitrate to the MXene material precursor, then add the aqueous sodium hydroxide solution dropwise, stir magnetically at room temperature for 10 hours, add polyvinylpyrrolidone, stir and let stand.

S3: Add the methanol solution of trimesic acid to the product of step S2, stir slowly for 2 hours at room temperature, and then centrifuge. The centrifuged product is then dispersed in a mixed solution of ethanol and deionized water to obtain MXene/HKUST-1 Solution, add polydopamine and stir for 30 minutes, spray onto the interdigital electrode plane, and vacuum dry at 50°C to obtain the gas sensor.

The composite weight ratio of Ti ₃ C ₂ and HKUST-1 is 1:1.12.

The concentration of the copper nitrate aqueous solution is 15mM; the concentration of the sodium hydroxide aqueous solution is 18mM.

The preparation steps of the MXene material precursor are as follows:

(1) Ti ₃ AlC ₂ and NaOH are evenly dispersed in the crucible, then moved to a quartz tube, nitrogen gas is passed in, the temperature is raised to 500°C, and the reaction is carried out for 30 hours and then cooled to room temperature.

(2) Move the above product into the reaction kettle, add deionized water, and then sonicate for 40 minutes to obtain a suspension, which is the MXene material precursor.

The molar ratio of Ti ₃ AlC ₂ and NaOH is 1:13.

The heating rate is 0.5°C/min.

The concentration of the methanol solution of trimesic acid is 0.05 mg/mL.

The volume ratio of the copper nitrate aqueous solution, sodium hydroxide aqueous solution and polyvinylpyrrolidone is 1:0.3:0.15.

The volume ratio of the aqueous solution of copper nitrate and the methanol solution of trimesic acid is 1:0.6.

The volume ratio of ethanol and deionized water is 1:1.2.

The centrifugation rate is 6000 r/min, and the centrifugation time is 4 minutes; the amount of polydopamine added accounts for 20% of the MXene/HKUST-1 solution.

Example 2

A method for preparing a new type of gas sensor, including the following steps:

S1: Preparation of MXene material precursor.

S2: Add the aqueous solution of copper nitrate to the MXene material precursor, then add the aqueous sodium hydroxide solution dropwise, stir magnetically at room temperature for 20 hours, add polyvinylpyrrolidone, stir and let stand.

S3: Add the methanol solution of trimesic acid to the product of step S2, stir slowly for 3 hours at room temperature, and then centrifuge. The centrifuged product is then dispersed in a mixed solution of ethanol and deionized water to obtain MXene/HKUST-1 Solution, add polydopamine and stir for 50 minutes, spray onto the interdigital electrode plane, and vacuum dry at 65°C to obtain the gas sensor.

The composite weight ratio of Ti ₃ C ₂ and HKUST-1 is 1:1.82.

The concentration of the copper nitrate aqueous solution is 20mM; the concentration of the sodium hydroxide aqueous solution is 22mM.

The preparation steps of the MXene material precursor are as follows:

(1) Ti ₃ AlC ₂ and NaOH are evenly dispersed in the crucible, then moved to a quartz tube, nitrogen gas is passed in, the temperature is raised to 600°C, and the reaction is carried out for 50 hours and then cooled to room temperature.

(2) Move the above product into the reaction kettle, add deionized water, and then sonicate for 60 minutes to obtain a suspension, which is the MXene material precursor.

The molar ratio of Ti ₃ AlC ₂ and NaOH is 1:16.

The heating rate is 0.8°C/min.

The concentration of the methanol solution of trimesic acid is 0.09 mg/mL.

The volume ratio of the copper nitrate aqueous solution, sodium hydroxide aqueous solution and polyvinylpyrrolidone is 1:0.4:0.35.

The volume ratio of the aqueous solution of copper nitrate and the methanol solution of trimesic acid is 1:0.9.

The volume ratio of ethanol and deionized water is 1:2.

The centrifugation rate is 8000 r/min, and the centrifugation time is 8 minutes; the amount of polydopamine added accounts for 30% of the MXene/HKUST-1 solution.

Example 3

A method for preparing a new type of gas sensor, including the following steps:

S1: Preparation of MXene material precursor.

S2: Add the aqueous solution of copper nitrate to the MXene material precursor, then add the aqueous sodium hydroxide solution dropwise, stir magnetically at room temperature for 15 hours, add polyvinylpyrrolidone, stir and let stand.

S3: Add the methanol solution of trimesic acid to the product of step S2, stir slowly for 3 hours at room temperature, and then centrifuge. The centrifuged product is then dispersed in a mixed solution of ethanol and deionized water to obtain MXene/HKUST-1 The solution was added with polydopamine and stirred for 40 minutes, then sprayed onto the interdigital electrode plane, and vacuum dried at 55°C to obtain the gas sensor.

The composite weight ratio of Ti ₃ C ₂ and HKUST-1 is 1:1.32.

The concentration of the copper nitrate aqueous solution is 16mM; the concentration of the sodium hydroxide aqueous solution is 20mM.

The preparation steps of the MXene material precursor are as follows:

(1) Ti ₃ AlC ₂ and NaOH are evenly dispersed in the crucible, then moved to a quartz tube, nitrogen gas is passed in, the temperature is raised to 550°C, and the reaction is carried out for 40 hours and then cooled to room temperature.

(2) Move the above product into the reaction kettle, add deionized water, and then sonicate for 50 minutes to obtain a suspension, which is the MXene material precursor.

The molar ratio of Ti ₃ AlC ₂ and NaOH is 1:14.

The heating rate is 0.6°C/min.

The concentration of the methanol solution of trimesic acid is 0.07 mg/mL.

The volume ratio of the copper nitrate aqueous solution, sodium hydroxide aqueous solution and polyvinylpyrrolidone is 1:0.35:0.22.

The volume ratio of the aqueous solution of copper nitrate and the methanol solution of trimesic acid is 1:0.7.

The volume ratio of ethanol and deionized water is 1:1.5.

The centrifugation rate is 7000 r/min, and the centrifugation time is 5 minutes; the amount of polydopamine added accounts for 25% of the MXene/HKUST-1 solution.

Example 4

A method for preparing a new type of gas sensor, including the following steps:

S1: Preparation of MXene material precursor.

S2: Add the aqueous solution of copper nitrate to the MXene material precursor, then add the aqueous sodium hydroxide solution dropwise, stir magnetically at room temperature for 18 hours, add polyvinylpyrrolidone, stir and let stand.

S3: Add the methanol solution of trimesic acid to the product of step S2, stir slowly for 2 hours at room temperature, and then centrifuge. The centrifuged product is then dispersed in a mixed solution of ethanol and deionized water to obtain MXene/HKUST-1 Solution, add polydopamine and stir for 30 to 50 minutes, spray onto the interdigital electrode plane, and vacuum dry at 60°C to obtain the gas sensor.

The composite weight ratio of Ti ₃ C ₂ and HKUST-1 is 1:1.68.

The concentration of the copper nitrate aqueous solution is 18mM; the concentration of the sodium hydroxide aqueous solution is 21mM.

The preparation steps of the MXene material precursor are as follows:

(1) Ti ₃ AlC ₂ and NaOH are evenly dispersed in the crucible, then moved to a quartz tube, nitrogen gas is passed in, the temperature is raised to 550°C, and the reaction is carried out for 45 hours and then cooled to room temperature.

(2) Move the above product into the reaction kettle, add deionized water, and then sonicate for 50 minutes to obtain a suspension, which is the MXene material precursor.

The molar ratio of Ti ₃ AlC ₂ and NaOH is 1:15.

The heating rate is 07°C/min.

The concentration of the methanol solution of trimesic acid is 0.08 mg/mL.

The volume ratio of the copper nitrate aqueous solution, sodium hydroxide aqueous solution and polyvinylpyrrolidone is 1:0.38:0.32.

The volume ratio of the aqueous solution of copper nitrate and the methanol solution of trimesic acid is 1:0.8.

The volume ratio of ethanol and deionized water is 1:1.8.

The centrifugation rate is 7000 r/min, and the centrifugation time is 7 minutes; the amount of polydopamine added accounts for 28% of the MXene/HKUST-1 solution.

Comparative example 1

A method for preparing a gas sensor, including the following steps:

S1: Add GO to deionized water, add the aqueous solution of copper nitrate after ultrasonic vibration for 2 hours, and stir magnetically for 25 hours. The mass volume ratio of GO and deionized water is 1 mg: 0.3 mL; the concentration of the copper nitrate aqueous solution is 20mM.

S2: Add the sodium hydroxide aqueous solution dropwise to the product of step S1, where the concentration of the sodium hydroxide aqueous solution is 22mM, let it stand at room temperature for 20h, then add polyvinylpyrrolidone, stir, transfer to the reaction kettle, and heat at 85°C React under high temperature and high pressure for 8 hours and then cool.

S3: Add the methanol solution of trimesic acid to the product of step S2, stir slowly for 3 hours at room temperature, and then centrifuge. The centrifuged product is then dispersed in a mixed solution of ethanol and deionized water to obtain rGO/HKUST-1 The solution was sprayed onto the interdigital electrode plane, and vacuum dried at 65°C to obtain the gas sensor.

The composite weight ratio of rGO and HKUST-1 is 1:1.82.

The concentration of the methanol solution of trimesic acid is 0.09 mg/mL.

The volume ratio of the copper nitrate aqueous solution, sodium hydroxide aqueous solution and polyvinylpyrrolidone is 1:0.4:0.35.

The volume ratio of the aqueous solution of copper nitrate and the methanol solution of trimesic acid is 1:0.9.

The volume ratio of ethanol and deionized water is 1:2; the centrifugation rate is 8000r/min, and the centrifugation time is 8min.

Comparative example 2

A method for preparing a new type of gas sensor, including the following steps:

S1: Preparation of MXene material precursor.

S2: Add the aqueous solution of copper nitrate to the MXene material precursor, then add the aqueous sodium hydroxide solution dropwise, stir magnetically at room temperature for 10 hours, add polyvinylpyrrolidone, stir and let stand.

S3: Add the methanol solution of trimesic acid to the product of step S2, stir slowly for 2 hours at room temperature, and then centrifuge. The centrifuged product is then dispersed in a mixed solution of ethanol and deionized water to obtain MXene/HKUST-1 The solution is sprayed onto the plane of the interdigital electrode, and the gas sensor is obtained after vacuum drying at 50°C.

The composite weight ratio of Ti ₃ C ₂ and HKUST-1 is 1:1.12.

The concentration of the copper nitrate aqueous solution is 15mM; the concentration of the sodium hydroxide aqueous solution is 18mM.

The preparation steps of the MXene material precursor are as follows:

(1) Ti ₃ AlC ₂ and NaOH are evenly dispersed in the crucible, then moved to a quartz tube, nitrogen gas is passed in, the temperature is raised to 500°C, and the reaction is carried out for 30 hours and then cooled to room temperature.

(2) Move the above product into the reaction kettle, add deionized water, and then sonicate for 40 minutes to obtain a suspension, which is the MXene material precursor.

The molar ratio of Ti ₃ AlC ₂ and NaOH is 1:13.

The heating rate is 0.5°C/min.

The concentration of the methanol solution of trimesic acid is 0.05 mg/mL.

The volume ratio of the copper nitrate aqueous solution, sodium hydroxide aqueous solution and polyvinylpyrrolidone is 1:0.3:0.15.

The volume ratio of the aqueous solution of copper nitrate and the methanol solution of trimesic acid is 1:0.6.

The volume ratio of ethanol and deionized water is 1:1.2.

The centrifugation rate is 6000r/min, and the centrifugation time is 4min.

Performance Testing:

The gas sensor material prepared in the example was used to detect NH ₃ (150 ppm), and the responsivity results obtained are shown in Table 1. The test was to test the corresponding resistance value in an environment of 25°C, using The following formula is used to calculate the responsiveness.

Responsiveness calculation:

R=(R _g -R _a )/R _a ;

Among them, R _a - the resistance value of the gas sensor in the background gas (Ω);

R _g —The resistance value of the gas sensor in the target gas (Ω).

Table 1. Test results:

It can be seen from Table 1 that compared with the responsiveness of the sensor material to ammonia gas in Comparative Example 1, the responsiveness of the sensor materials prepared in Examples 1 to 4 of the present invention to ammonia gas is increased by about 1.4 times, effectively Improved response to ammonia gas.

In order to detect the gas sensitivity selectivity test (50ppmNH ₃ ) of the gas sensor at 60°C, the gas sensitivity selectivity test of the gas sensor to H ₂ O, CO, CO ₂ , H ₂ and NH ₃ was performed respectively. The test results are as shown in the table As shown in 2,

Table 2. Test results:

It can be seen from Table 2 that the gas sensor materials prepared in Examples 1 to 4 have a greater response to ammonia than to other gases, indicating that the sensor of the present invention has more excellent selectivity for ammonia; at the same time, the comparative example The sensor in Comparative Example 1 also has excellent selectivity for ammonia than for other gases, but the response of the sensor to ammonia in Comparative Example 1 is 1.4 times that of H ₂ O, while the sensor of the present invention is more selective for ammonia than for other gases. The response is 4.1 times that of H ₂ O, indicating that the sensor of the present invention receives less interference from water vapor.

In order to detect the impact of water vapor on the gas sensitivity selectivity of the gas sensor at 60°C (50ppmNH ₃ ), the gas sensor was tested for H ₂ O, CO, CO ₂ , H ₂ , NH in Example 1 and Comparative Example 2 respectively. ₃ gas sensitivity selectivity test, the test results are shown in Table 3,

Table 3. Test results:

As can be seen from Table 3, the response of the sensor in Comparative Example 2 to ammonia gas is twice that of water vapor, indicating that the sensor in Comparative Example 2 is affected by water vapor compared to the sensor in Example 1. The impact is greater.

Claims (10)

1. The novel gas sensor is characterized by comprising interdigital electrodes and a sensitive composite film material; the sensitive composite film material comprises an MXene material and a metal organic framework material; the MXene material is Ti ₃ C ₂ The metal organic framework material is HKUST-1.

2. The novel gas sensor according to claim 1, wherein the sensitive composite film material is Ti in MXene/HKUST-1 ₃ C ₂ And HKUST-1 is 1: (1.12-1.82).

3. A method of manufacturing a novel gas sensor according to claim 1 or 2, characterized in that the method of manufacturing comprises the steps of:

s1: preparing an MXene material precursor;

s2: adding an aqueous solution of copper nitrate into an MXene material precursor, then dropwise adding an aqueous solution of sodium hydroxide, magnetically stirring at room temperature for 10-20 h, adding polyvinylpyrrolidone, stirring, and standing;

s3: and (3) adding a methanol solution of trimesic acid into the product of the step (S2), slowly stirring at room temperature for 2-3 hours, centrifuging, dispersing the centrifuged product into a mixed solution of ethanol and deionized water to obtain a MXene/HKUST-1 solution, adding polydopamine, stirring for 30-50 minutes, spraying onto the plane of an interdigital electrode, and vacuum drying at 50-65 ℃ to obtain the gas sensor.

4. A method of manufacturing a novel gas sensor according to claim 3, wherein the copper nitrate aqueous solution has a concentration of 15 to 20mM;

and/or the concentration of the sodium hydroxide aqueous solution is 18-22 mM.

5. A method of manufacturing a novel gas sensor according to claim 3, wherein the MXene material precursor is prepared by the steps of:

(1) Part Ti ₃ AlC ₂ Uniformly dispersing NaOH and the mixture in a crucible, then moving the crucible into a quartz tube, introducing nitrogen, heating to 500-600 ℃ for reaction for 30-50 hours, and cooling to room temperature;

(2) And transferring the product into a reaction kettle, adding deionized water, and performing ultrasonic treatment for 40-60 min to obtain a suspension, namely the precursor of the MXene material.

6. The method for manufacturing a novel gas sensor according to claim 5, wherein the Ti is ₃ AlC ₂ And NaOH in a molar ratio of 1:13-16.

7. The method for manufacturing a novel gas sensor according to claim 5, wherein the temperature rising rate is 0.5-0.8 ℃/min.

8. The method for manufacturing a novel gas sensor according to claim 3, wherein the concentration of the trimesic acid in the methanol solution is 0.05-0.09 mg/mL.

9. The method for preparing a novel gas sensor according to claim 3, wherein the volume ratio of the aqueous solution of copper nitrate, the aqueous solution of sodium hydroxide and the polyvinylpyrrolidone is 1: (0.3-0.4): (0.15-0.35);

and/or the number of the groups of groups,

the volume ratio of the aqueous solution of copper nitrate to the methanol solution of trimesic acid is 1: (0.6 to 0.9);

and/or the number of the groups of groups,

the volume ratio of the ethanol to the deionized water is 1: 1.2-2.

10. The method for manufacturing a novel gas sensor according to claim 3, wherein the centrifugation rate is 6000-8000 r/min and the centrifugation time is 4-8 min;

and/or the number of the groups of groups,

the added amount of the polydopamine accounts for 20-30% of the MXene/HKUST-1 solution.