Preparation method of an ultrasensitive room-temperature hydrogen sensor

Abstract

The present invention discloses a preparation method of an ultrasensitive room-temperature hydrogen sensor. In this method, first, DNA, deionized water, 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt, and acetic acid are taken and mixed and magnetically stirred for 2 h to obtain a uniform solution A. An aqueous solution of graphene oxide is added to a solution obtained by adding one of palladium dichloride, nickel nitrate hexahydrate, or cobalt nitrate hexahydrate and graphene oxide to deionized water, and ultrasonic treatment is carried out to completely dissolve palladium dichloride. The obtained clear solution is added to solution B, and hydrazine is added, followed by continuous magnetic stirring to make the solution uniformly mixed. The obtained mixed solution is poured into a reaction kettle for hydrothermal reaction, and then the hydrothermal reaction product is washed with deionized water. The washed reaction product is quickly frozen with liquid nitrogen and placed in a freeze-drying device for freeze-drying to finally obtain a gas-sensitive material. The hydrogen sensor of the present invention does not require any heating and can directly work at room temperature. The detected hydrogen concentration can be as low as 50 ppb, and the response time is short.

Description

Technical Field

[0001] The present invention relates to a resistive hydrogen sensor, and particularly to an ultrasensitive room-temperature hydrogen sensor, which can be used for early safety warning of lithium-ion batteries and various fields involving hydrogen. Background Art

[0002] Due to advantages such as high energy density, long cycle life, and environmental friendliness, lithium-ion batteries have become one of the most competitive electrochemical energy storage technologies in the fields of electric vehicles and large-scale energy storage. Excessively high temperature of the battery system is extremely likely to induce an exothermic chain reaction inside the battery, causing the battery to rapidly heat up, leading to smoking, fire, or even explosion. Research has found that a small amount of H2 is often generated inside the lithium battery before it gets out of control. Rapid detection of trace H2 is the most effective means for early safety warning of lithium-ion batteries. Semiconductor resistive gas sensors are small in size, low in cost, and high in sensitivity, and are currently the most widely used and studied, and can be directly integrated with integrated circuits. However, currently, resistive hydrogen sensors have a high detection concentration and a high operating temperature. Due to the flammability and explosiveness of hydrogen, the high operating temperature of the device will pose a safety hazard.

[0003] In response to this, the present invention has for the first time developed an ultrasensitive room-temperature hydrogen sensor for low-concentration hydrogen detection, which is particularly suitable for early safety warning of lithium-ion batteries and also suitable for safety monitoring in various application scenarios involving hydrogen. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the present invention has developed an ultrasensitive room-temperature hydrogen sensor based on graphene. The sensor prepared from this gas-sensitive material can detect ultra-low-concentration hydrogen at room temperature.

[0005] A preparation method for an ultrasensitive room-temperature hydrogen sensor is as follows:

[0006] Step (1): Take DNA, deionized water, 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt, and acetic acid, mix them, and stir magnetically for 2 h to obtain a uniform solution A; wherein the mass ratio of DNA to the volume of deionized water is 60-200:1, the mass ratio of 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt to the volume of deionized water is 3000:2, and the mass ratio of acetic acid to the volume of deionized water is 21:2;

[0007] Step (2): Add 1 mol / L graphene oxide aqueous solution to solution A obtained in step (1), and stir magnetically for 12 h to obtain solution B; the volume ratio of deionized water to graphene oxide aqueous solution is 2:3 - 5; Step (3): Take one of palladium dichloride, nickel nitrate hexahydrate or cobalt nitrate hexahydrate, and add it to deionized water at a molar ratio of 1:20 to the graphene oxide used in step (2), and ultrasonicate for 30 min to completely dissolve palladium dichloride, nickel nitrate hexahydrate or cobalt nitrate hexahydrate to obtain a clear solution. Add the obtained clear solution to solution B obtained in step (2), and add hydrazine, and continue to stir magnetically for 30 min to make the solution mix evenly; the volume of deionized water in step (3) is the same as that in step (1); the volume ratio of hydrazine in step (3) to the graphene oxide aqueous solution added in step (2) is 2 - 3:1;

[0008] Step (4): Pour the mixed solution obtained in step (3) into a reaction kettle, carry out hydrothermal reaction at 80 - 100 °C for 80 - 150 min, and then wash the hydrothermal reaction product with deionized water for more than 3 times;

[0009] Step (5): Quickly freeze the washed reaction product in step (4) with liquid nitrogen for 5 min, and then put it into a freeze-drying device for freeze-drying at -4 °C for 36 - 50 h. The finally obtained product is the gas-sensitive material;

[0010] Step (6): Take the gas-sensitive material obtained in step (5) for grinding. According to the mass ratio of the gas-sensitive material to ethylene glycol of 1:30, gradually add ethylene glycol dropwise while grinding until a uniform slurry is obtained. Take an appropriate amount of the slurry and coat it on the surface of the sensor electrode of the ceramic substrate, and then heat at 60 - 90 °C for more than 24 h to obtain an ultrasensitive room-temperature hydrogen sensor.

[0011] Preferably, the DNA concentration of the precursor solution prepared in step (1) is 60 g / L to 200 g / L.

[0012] Preferably, the mass ratio of DNA, 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt and acetic acid added in step (1) is 40:1000:7 to 120:1000:7.

[0013] Preferably, wash with deionized water 5 times in step (4).

[0014] Preferably, the concentration of the palladium dichloride, or nickel nitrate hexahydrate, or cobalt nitrate hexahydrate solution prepared in step (3) is 0.1 mol / L.

[0015] Preferably, freeze-dry at -4 °C for 40 - 48 h in step (5).

[0016] Preferably, the DNA is sodium deoxyribonucleate, CAS No.: 100403-24-5.

[0017] Advantages:

[0018] 1. The hydrogen sensor of the present invention does not require any heating and can directly operate at room temperature;

[0019] 2. The hydrogen sensor of the present invention can detect hydrogen concentration as low as 50 ppb at room temperature;

[0020] 3. The response time of the hydrogen sensor of the present invention for detecting hydrogen at room temperature is 20 - 30 s, and the recovery time is 30 - 40 s. Description of the Drawings

[0021] Figure 1 It is a schematic diagram of the room temperature hydrogen sensor in the present invention;

[0022] Figure 2 The response / recovery curve of the sensor in Example 1 for detecting ultra-low concentration hydrogen;

[0023] Figure 3 The response / recovery curve of the sensor in Example 2 for detecting ultra-low concentration hydrogen;

[0024] Figure 4 The response / recovery curve of the sensor in Example 3 for detecting ultra-low concentration hydrogen;

[0025] Figure 5 The response / recovery curve of the sensor in Example 4 for detecting ultra-low concentration hydrogen;

[0026] Figure 6 The response / recovery curve of the sensor in Example 5 for detecting ultra-low concentration hydrogen. Detailed Embodiments

[0027] Example 1

[0028] (1) Take 240 mg of DNA, 2 ml of deionized water, 3 g of 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt, and 21 μl of acetic acid, mix and stir magnetically for 10 h to obtain a uniform solution A;

[0029] (2) Take 4 ml of 1 mol / L graphene oxide aqueous solution and add it to the solution A obtained in step (1), stir magnetically for 2 h to obtain solution B;

[0030] (3) Take 0.2 mmol of palladium dichloride and add it to 2 ml of deionized water, ultrasonicate for 30 min to completely dissolve palladium dichloride to obtain a clear solution, add the obtained clear solution to the solution B obtained in step (2), and add 10 μl of hydrazine, continue to stir magnetically for 30 min to make the solution evenly mixed;

[0031] (4) Pour the mixed solution obtained in step (3) into a reaction kettle, carry out hydrothermal reaction at 80 °C for 2 h, and then wash the hydrothermal reaction product with deionized water three times;

[0032] (5) Rapidly freeze the washed reaction product in step (4) with liquid nitrogen for 5 min, and then put it into a freeze-drying device for freeze-drying at -4 °C for 48 h. The finally obtained product is the gas-sensitive material;

[0033] (6) Take 0.05 mg of the gas-sensitive material obtained in step (5), add 2 μL of ethylene glycol dropwise while grinding, grind until a uniform slurry is obtained, take an appropriate amount of the slurry and coat it on the surface of the sensor electrode of the ceramic substrate, and then heat it at 60 °C for 48 h to obtain an ultrasensitive room-temperature hydrogen sensor.

[0034] The room-temperature hydrogen sensor prepared in Example 1 is as Figure 1 shown. Using a ceramic chip as the substrate, there is only a pair of interdigital electrodes for the output of the sensor current signal;

[0035] The response / recovery change of the current value of the hydrogen sensor prepared in Example 1 to 0.05 - 5 ppm hydrogen at room temperature and the sensitivity to different concentrations of hydrogen are as Figure 2 shown. The sensitivity to 0.05 ppm hydrogen is as high as 60 / ppm, the response time to different concentrations of hydrogen is 20 - 30 s, and the recovery time is 30 - 40 s.

[0036] Example 2

[0037] This example is similar to Example 1, except that the DNA used in step (1) is 160 mg.

[0038] The response / recovery change of the current value of the hydrogen sensor prepared in Example 2 to 0.05 - 5 ppm hydrogen at room temperature and the sensitivity to different concentrations of hydrogen are as Figure 3 shown. The sensitivity to 0.05 ppm hydrogen is as high as 45 / ppm, the response time to different concentrations of hydrogen is 30 - 40 s, and the recovery time is 40 - 50 s.

[0039] Example 3

[0040] This example is similar to Example 1, except that the DNA used in step (1) is 360 mg.

[0041] The response / recovery change of the current value of the hydrogen sensor prepared in Example 3 to 0.05 - 5 ppm hydrogen at room temperature and the sensitivity to different concentrations of hydrogen are as Figure 4 shown. The sensitivity to 0.05 ppm hydrogen is as high as 57 / ppm.

[0042] Example 4

[0043] This example is similar to Example 1, except that the metal salt used in step (3) is 0.02 mmol nickel nitrate hexahydrate.

[0044] The response / recovery changes of the hydrogen sensor prepared in Example 4 to 0.05 - 5 ppm hydrogen at room temperature and the sensitivity to different concentrations of hydrogen are as Figure 5 shown, and the sensitivity to 0.05 ppm hydrogen is as high as 34 / ppm.

[0045] Example 5

[0046] This example is similar to Example 1, except that the metal salt used in step (3) is 0.02 mmol cobalt nitrate hexahydrate.

[0047] The response / recovery changes of the hydrogen sensor prepared in Example 5 to 0.05 - 5 ppm hydrogen at room temperature and the sensitivity to different concentrations of hydrogen are as Figure 6 shown, and the sensitivity to 0.05 ppm hydrogen is as high as 15 / ppm.

[0048] The present invention uses the dynamic gas distribution method to measure the sensitive characteristics of the hydrogen sensor. When detecting hydrogen, the sensor voltage is 5V, and the sensor sensitivity is defined as

[0049]

[0050] where I s represents the current value of the sensor in a certain concentration of hydrogen to be detected, I0 represents the current value of the sensor in the background gas, C represents the detected hydrogen concentration, and the unit of C is ppm.

Claims

1. A preparation method of an ultrasensitive room-temperature hydrogen sensor, characterized in that, The method specifically includes the following steps: Step (1): Take DNA, deionized water, 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt, and acetic acid, mix them, and stir magnetically for 2 h to obtain a uniform solution A; the DNA is sodium protamine DNA, CAS No.: 100403-24-5, the mass ratio of DNA to the volume of deionized water is (60-200) g:1 L, the mass ratio of 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt to the volume of deionized water is 3000 g:2 L, and the volume ratio of acetic acid to deionized water is 21 μl:2 ml; Step (2): Take a 1 mol / L aqueous solution of graphene oxide and add it to solution A obtained in step (1), stir magnetically for 12 h to obtain solution B; the volume ratio of deionized water to the aqueous solution of graphene oxide is 2:3-5; Step (3): Take one of palladium dichloride, nickel nitrate hexahydrate, or cobalt nitrate hexahydrate, and add it to deionized water at a molar ratio of 1:20 to the graphene oxide used in step (2), sonicate for 30 min to completely dissolve palladium dichloride, nickel nitrate hexahydrate, or cobalt nitrate hexahydrate to obtain a clear solution, add the obtained clear solution to solution B obtained in step (2), and add hydrazine, then continue to stir magnetically for 30 min to make the solution evenly mixed; the volume of deionized water in step (3) is the same as the volume of deionized water in step (1); the volume ratio of hydrazine in step (3) to the aqueous solution of graphene oxide added in step (2) is 2-3:1; Step (4): Pour the mixed solution obtained in step (3) into a reaction kettle, carry out a hydrothermal reaction at 80-100 °C for 80-150 min, and then wash the hydrothermal reaction product with deionized water more than 3 times; Step (5): Quickly freeze the washed reaction product in step (4) with liquid nitrogen for 5 min, and then place it in a freeze-drying device to carry out freeze-drying at -4 °C for 36-50 h, and the finally obtained product is the gas-sensitive material; Step (6): Take the gas-sensitive material obtained in step (5) and grind it. According to the mass ratio of the gas-sensitive material to ethylene glycol of 1:30, add ethylene glycol drop by drop while grinding until a uniform slurry is obtained. Take an appropriate amount of the slurry and coat it on the surface of the sensor electrode of the ceramic substrate, and then heat it at 60-90 °C for more than 24 h to obtain an ultrasensitive room-temperature hydrogen sensor.

2. The preparation method of a super-sensitive room-temperature hydrogen sensor according to claim 1, characterized in that, The concentration of DNA in solution A prepared in step (1) is 60 g / L to 200 g / L.

3. The preparation method of a super-sensitive room-temperature hydrogen sensor according to claim 1, characterized in that, The mass ratio of DNA, 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt, and acetic acid added in step (1) is 40:1000:7 to 120:1000:

7.

4. The preparation method of a highly sensitive room-temperature hydrogen sensor according to claim 1, characterized in that: Wash 5 times with deionized water in step (4).

5. The preparation method of a super-sensitive room-temperature hydrogen sensor according to claim 1, characterized in that, The concentration of palladium dichloride, nickel nitrate hexahydrate, or cobalt nitrate hexahydrate in the clear solution prepared in step (3) is 0.1 mol / L.

6. The preparation method of a highly sensitive room-temperature hydrogen sensor according to claim 1, characterized in that: Carry out freeze-drying at -4 °C for 40-48 h in step (5).

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