Nickel oxide-based semiconductor gas-sensitive material, preparation method and application thereof, and hemp gas-sensitive sensor

Abstract

The invention provides a nickel oxide-based semiconductor gas-sensitive material, a preparation method and application thereof, and a hemp gas-sensitive sensor, and belongs to the technical field of gas-sensitive sensors. The preparation method comprises the following steps: taking a nickel source as a raw material, adding an additive and urea, taking water as a solvent, synthesizing nickel oxide by adopting a hydrothermal method, and then modifying ions of the nickel oxide by adopting a modifier to obtain the nickel oxide-based semiconductor gas-sensitive material with the mesoporous structure. The prepared nickel oxide-based semiconductor gas-sensitive material with the mesoporous structure has high sensitivity and quick response to 3-methyl-2-butene-1-mercaptan serving as a main odor component of hemp, and a prepared gas-sensitive sensor has the advantages of high inspection speed, small volume, portability and the like, can be applied to supervision fields such as customs investigation and the like, and has wide application prospects. The method can enrich the finding means of precursor chemicals and flammable and explosive chemicals.

Description

Technical Field

[0001] The present invention relates to the technical field of gas sensors, and in particular to a nickel oxide-based semiconductor gas-sensitive material, a preparation method and application thereof, and a hemp gas sensor. Background Art

[0002] So far, the research and production of metal oxide semiconductor gas sensors has a history of more than 50 years. Due to the advantages of good thermal stability, low material cost, stable components, and simple manufacturing process, metal oxide semiconductors have become one of the sensor materials with the largest output, the most types, and the most extensive applications in the world.

[0003] In recent years, gas sensors have been used at home and abroad to detect odor molecules and identify the quality and species of animals and plants. For example, the French AlphaMOS sensor is mainly used for the quality identification of products such as meat, coffee, and grains, the British Aroma SCAN sensor is mainly used for the quality inspection of cheese and meat products, and the German Airsense sensor is mainly used for the analysis and identification of beverages, meat, grains, and aquatic products. Domestic related companies have also carried out research in related fields. For example, the gas alarm and ethanol sensors produced by Weisheng Company belong to this type of sensor. Domestic and foreign researchers have studied the sensitive materials required for port quarantine. Liu Fengjun et al. (Fabrication of 1D Zn2SnO4 nanowire and 2D ZnOnanosheet hybrid hierarchical structures for use in triethylamine gas sensors, Sensors & Actuators: B Chemical, 2019, 291, 155-163.) prepared a Zn2SnO4 / ZnO heterostructure, which has excellent gas-sensitive properties for triethylamine and is used for the detection of shrimps, sea cucumbers, etc. Vellingiri Kowsalya et al. (Validation of'lock-and-key'mechanism ofa metal–organic framework inselective sensing oftrimethylamine,RSCAdvances,2019,9,7818-7825.) reported a metal-organic framework material that also exhibited excellent gas-sensing properties for triethylamine. Xie Xiang et al. (Facilesynthesis and superior ethyl acetate sensing performance of Au decorated ZnOflower-like architectures,Ceramics International,2017,43,5053-5060.) prepared Au-modified ZnO flower-like structures, which have excellent gas-sensing properties for ethyl acetate and can be used for the detection of foreign fruits at border ports. From the above analysis of the current status of research at home and abroad, it can be seen that the application of gas sensors in the field of customs inspection has good feasibility.

[0004] At present, for the inspection of precursor drugs and explosives at customs ports, the existing method is mainly to randomly inspect goods through X-ray machines at a certain ratio, which makes it difficult to achieve full coverage; drug detection dogs also have olfactory fatigue and periodic problems in their work. Since November 2021, the US research team has discovered that the special smell of marijuana is mainly composed of sulfides, especially 3-methyl-2-butene-1-thiol. However, to date, there has been no research and report on semiconductor gas-sensitive materials and semiconductor gas-sensitive sensors for detecting the odor of marijuana. Therefore, the development and research of marijuana odor gas-sensitive semiconductor materials and gas-sensitive sensors with high sensitivity and selectivity is of great significance to the real-time and accurate monitoring of marijuana. Summary of the invention

[0005] The purpose of the present invention is to provide a nickel oxide-based semiconductor gas-sensitive material, a preparation method and application thereof, and a cannabis gas-sensitive sensor. The nickel oxide-based semiconductor gas-sensitive material can realize rapid identification and response to the odor of cannabis, has high sensitivity and selectivity, and is of great significance for realizing real-time and accurate monitoring of cannabis.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a nickel oxide-based semiconductor gas-sensitive material, comprising the following steps:

[0008] Mixing the nickel source, the additive, urea and water, and performing hydrothermal treatment to obtain a hydrothermal product;

[0009] The hydrothermal product is subjected to a first calcination to obtain nickel oxide;

[0010] The nickel oxide, water and a modifier are mixed and modified to obtain a precursor;

[0011] The precursor is subjected to a second calcination to obtain a nickel oxide-based semiconductor gas-sensitive material;

[0012] The additives include a binder and / or a metal compound;

[0013] The modifying agents include chloroauric acid, lysine and sodium borohydride.

[0014] Preferably, the nickel source includes nickel chloride; the binder includes one or more of PVP, PVA, CMC and PEG; and the metal compound includes one or more of cadmium nitrate, chromium nitrate, indium nitrate and silver nitrate.

[0015] Preferably, the mass ratio of the nickel source, additive, urea and water is 0.5-4:0.1-1:1-6:90-99.

[0016] Preferably, the temperature of the hydrothermal treatment is 120-180° C., and the time is 4-12 hours.

[0017] Preferably, the temperature of the first calcination is 300-800° C., and the time is 2-4 hours.

[0018] Preferably, the molar ratio of nickel oxide to modifier is (2-5):(0.5-2); the molar ratio of chloroauric acid, lysine and sodium borohydride in the modifier is (0.5-2.5):(1-12):(90-200); the modification temperature is 25-80°C and the modification time is 30-100 min.

[0019] Preferably, the second calcination is performed at a temperature of 200 to 500° C. and for a time of 1 to 3 hours.

[0020] The present invention provides a nickel oxide-based semiconductor gas-sensitive material prepared by the preparation method described in the above technical solution.

[0021] The present invention provides the application of the nickel oxide-based semiconductor gas-sensitive material described in the above technical solution in monitoring the odor of marijuana.

[0022] The present invention provides a cannabis gas sensor, which adopts the nickel oxide-based semiconductor gas-sensitive material described in the above technical solution.

[0023] The present invention provides a method for preparing a nickel oxide-based semiconductor gas-sensitive material. The present invention uses a nickel source as a raw material, adds different additives and urea, uses water as a solvent, adopts a hydrothermal method to synthesize nickel oxide, and then uses a modifier to modify its ions to obtain a mesoporous nickel oxide-based semiconductor gas-sensitive material. The prepared mesoporous nickel oxide-based gas-sensitive material has typical P-type semiconductor characteristics, and the gas-sensitive reaction mainly occurs on the surface of the material. The gas-sensitive sensing is achieved by the change in carrier concentration caused by the target gas and the oxygen adsorbed on the surface of the material during the reaction process: the oxygen molecules in the air will be adsorbed on the surface of the NiO crystal and take electrons from the conduction band to form surface adsorbed oxygen, and the holes generated in the valence band will migrate to the surface, and finally form a hole accumulation layer on the surface close to NiO, so that NiO exhibits a low resistance value in the air. When the sensor containing the gas-sensitive material is exposed to 3-methyl-2-butene-1-thiol gas, the target gas molecules will be adsorbed on the surface of the material and react with O -When a reaction occurs, electrons will be released, and these released electrons will return to the conduction band and combine with holes, making the hole accumulation layer on the NiO surface thinner and increasing the sensor resistance. After NiO is modified with Au ions, due to the deposition of Au ions on the surface and the inner wall of the pores, it is more difficult for the electron beam to penetrate the porous sphere, which can increase the baseline resistance of the sensor and thus improve the sensor's response to 3-methyl-2-butene-1-thiol. Therefore, the nickel oxide-based semiconductor gas-sensitive material with a mesoporous structure prepared by the present invention has high sensitivity to 3-methyl-2-butene-1-thiol, the main odor component of cannabis, and fast response. The gas-sensitive sensor has the advantages of fast inspection rate, small size, and portability, and can be applied to regulatory fields such as customs inspection, and can enrich the means of seizing easy-to-prepare drugs and flammable and explosive chemicals.

[0024] The specific surface area of ​​the mesoporous nickel oxide-based semiconductor gas-sensitive material prepared by the present invention is as high as 73.665 m 2 / g, with an average pore size of 7.82nm. Due to its high powder surface activity and large specific surface area, it has high gas permeability, which significantly improves the gas sensitivity of nickel oxide and improves its selectivity for the odor of cannabis, especially the odor of 3-methyl-2-butene-1-thiol, the main component of cannabis, thereby realizing the monitoring of the odor of cannabis. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a scanning electron microscope image of the nickel oxide-based gas-sensitive material prepared in Example 1;

[0026] Figure 2 Isothermal adsorption-desorption curve and pore size distribution curve of the nickel oxide-based gas-sensitive material prepared in Example 1;

[0027] Figure 3 The sensitivity results of nickel oxide-based gas-sensitive materials to 3-methyl-2-butene-1-thiol under different modification conditions. DETAILED DESCRIPTION

[0028] In the present invention, unless otherwise specified, the required raw materials or reagents are commercially available products well known to those skilled in the art.

[0029] The present invention provides a method for preparing a nickel oxide-based semiconductor gas-sensitive material, comprising the following steps:

[0030] Mixing the nickel source, the additive, urea and water, and performing hydrothermal treatment to obtain a hydrothermal product;

[0031] The hydrothermal product is subjected to a first calcination to obtain nickel oxide;

[0032] The nickel oxide, water and a modifier are mixed and modified to obtain a precursor;

[0033] The precursor is subjected to a second calcination to obtain a nickel oxide-based semiconductor gas-sensitive material;

[0034] The additives include a binder and / or a metal compound;

[0035] The modifying agents include chloroauric acid, lysine and sodium borohydride.

[0036] In the present invention, the nickel source preferably includes nickel chloride; the binder preferably includes one or more of PVP, PVA, CMC and PEG; the metal compound preferably includes one or more of cadmium nitrate, chromium nitrate, indium nitrate and silver nitrate. When the binder or metal compound is two or more of the corresponding types, the present invention has no special limitation on the ratio of different types, and any ratio is acceptable.

[0037] In the present invention, the mass ratio of the nickel source, additive, urea and water is preferably 0.5-4:0.1-1:1-6:90-99, and more preferably 1-4:0.5-1:2-6:90-99.

[0038] In the present invention, the nickel source, additive, urea and water are preferably mixed by magnetic stirring, and the stirring time is preferably 10 to 40 minutes, more preferably 20 to 30 minutes.

[0039] In the present invention, the temperature of the hydrothermal treatment is preferably 120-180° C., more preferably 150-160° C., and the time is preferably 4-12 hours, more preferably 6-8 hours. During the hydrothermal treatment, the nickel source reacts with the additive and urea to generate nickel oxide.

[0040] After the hydrothermal treatment is completed, the present invention preferably cools the obtained product to room temperature and then sequentially performs suction filtration and drying to obtain a hydrothermal product; the drying temperature is preferably 60 to 100°C, more preferably 80 to 90°C.

[0041] In the present invention, the temperature of the first calcination is preferably 300-800°C, more preferably 500-600°C, and the time is preferably 2-4h, more preferably 2-3h. During the first calcination, nickel oxide reacts with oxygen in the air to generate nickel oxide at high temperature. When chromium ions are further added through metal compounds, the chromium ions are doped into the nickel oxide lattice to generate oxygen vacancies, which promotes the adsorption and ionization process of surface oxygen, and is beneficial to the improvement of gas sensing performance.

[0042] In the present invention, the nickel oxide, water and modifier are preferably mixed by ultrasonically dispersing the nickel oxide in water, and the ultrasonic time is preferably 10 to 30 minutes, more preferably 15 to 20 minutes; the modifier is added to the obtained suspension and stirred for modification.

[0043] In the present invention, the molar ratio of the nickel oxide to the modifier is preferably (2-5):(0.5-2), more preferably (2.4-4.0):(1.0-1.5), and further preferably 2.7:1.29; the molar ratio of chloroauric acid, lysine and sodium borohydride in the modifier is preferably (0.5-2.5):(1-12):(90-200), and more preferably 1:8:120.

[0044] The modifier of the present invention is preferably used in the form of a modifier solution, and the modifier solution preferably includes an aqueous solution of chloroauric acid (HAuCl4), lysine (C6H 14 N2O2) aqueous solution and sodium borohydride (NaBH4) aqueous solution; the concentration of the chloroauric acid aqueous solution is preferably 0.01-0.1 mol / L, the concentration of the lysine aqueous solution is preferably 0.01-0.1 mol / L, and the concentration of the sodium borohydride aqueous solution is preferably 0.1-0.5 mol / L; the volume ratio of the chloroauric acid aqueous solution, the lysine aqueous solution and the sodium borohydride aqueous solution is preferably 1-2.8:6.46-10:10-15.7, more preferably 1:8:12; the present invention preferably adds chloroauric acid aqueous solution and lysine aqueous solution to the obtained suspension, stirs for 30 minutes, then adds sodium borohydride aqueous solution, and stirs for modification.

[0045] In the present invention, the modification temperature is preferably 25 to 80° C., more preferably 25 to 30° C., and the modification time is preferably 30 to 100 min, more preferably 40 to 80 min. During the modification process, the uniform release of gold ions is controlled by the complexation of lysine, and chloroauric acid is reduced to Au ions under the action of sodium borohydride, so that the Au ions are further uniformly deposited on the mesoporous nickel oxide spheres.

[0046] After the modification is completed, the obtained product is preferably centrifuged, washed and dried in sequence to obtain an Au-modified mesoporous nickel oxide precursor. The solvent used for the centrifugal washing is preferably deionized water or anhydrous ethanol.

[0047] In the present invention, the temperature of the second calcination is preferably 200-500° C., more preferably 300-400° C., and the time is preferably 1-3 hours, more preferably 1-2 hours. In the present invention, residual lysine is removed by the second calcination.

[0048] The present invention provides a nickel oxide-based semiconductor gas-sensitive material prepared by the preparation method described in the above technical solution.

[0049] The present invention provides the application of the nickel oxide-based semiconductor gas-sensitive material described in the above technical solution in monitoring the odor of marijuana.

[0050] The present invention provides a cannabis gas sensor, which uses the nickel oxide-based semiconductor gas-sensitive material described in the above technical solution. The present invention has no special limitation on the specific structure of the cannabis gas sensor. The gas sensor structure known in the art uses the nickel oxide-based semiconductor gas-sensitive material described in the present invention as the gas-sensitive material, and adjusts the circuit and matching appropriate resistors in a conventional manner.

[0051] Since the special smell of cannabis is mainly composed of sulfides, especially 3-methyl-2-butene-1-thiol, the cannabis gas sensor of the present invention mainly performs gas sensing on 3-methyl-2-butene-1-thiol.

[0052] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0053] Example 1

[0054] Step 1: Take 1g nickel chloride, 0.5g PVP and 2g urea and add them into 60mL deionized water, stir magnetically for 20min to mix evenly, pour the resulting solution into a reactor, and hydroheat at 160℃ for 6h;

[0055] Step 2: After the reactor is cooled to room temperature, it is filtered and dried at 80°C. The obtained powder is calcined at 500°C for 2h to obtain nickel oxide powder;

[0056] Step 3: Take 0.2 g (0.0027 mol) of the above nickel oxide powder and ultrasonically disperse it in 120 mL of deionized water for 15 min;

[0057] Step 4: Add 1 mL of chloroauric acid aqueous solution (0.01 mol / L) and 8 mL of lysine aqueous solution (0.01 mol / L) to the suspension after ultrasonic dispersion, stir for 30 min, then add 12 mL of sodium borohydride aqueous solution (0.1 mol / L), continue stirring and modifying at 25 ° C for 40 min, collect the powder by centrifugation, wash the obtained powder with anhydrous ethanol and dry it to obtain a precursor of mesoporous nickel oxide;

[0058] Step 5: Calcine the obtained precursor at 300°C for 1 hour to obtain a nickel oxide-based gas-sensitive material.

[0059] Example 2

[0060] Step 1: Take 1g nickel chloride, 0.05g Cr(NO3)3 and 2g urea and add them into 60mL deionized water, stir magnetically for 20min to mix evenly, pour the resulting solution into a reactor, and hydroheat at 160℃ for 6h;

[0061] Step 2: After the reactor is cooled to room temperature, it is filtered and dried at 80°C. The obtained powder is calcined at 500°C for 2h to obtain nickel oxide powder;

[0062] Step 3: Take 0.2 g of the above nickel oxide powder and ultrasonically disperse it in 120 mL of deionized water for 15 min;

[0063] Step 4: Add 1 mL of chloroauric acid aqueous solution (0.01 mol / L) and 8 mL of lysine aqueous solution (0.01 mol / L) to the suspension after ultrasonic dispersion, stir for 30 min, then add 12 mL of sodium borohydride aqueous solution (0.1 mol / L), continue stirring and modifying at 25 ° C for 40 min, collect the powder by centrifugation, wash the obtained powder with anhydrous ethanol and dry it to obtain a precursor of mesoporous nickel oxide;

[0064] Step 5: Calcine the obtained precursor at 300°C for 1 hour to obtain a nickel oxide-based gas-sensitive material.

[0065] Example 3

[0066] Step 1: Take 1g nickel chloride, 0.075g Cr(NO3)3 and 2g urea and add them into 60mL deionized water, stir magnetically for 20min to mix evenly, pour the resulting solution into a reactor, and hydroheat at 160℃ for 6h;

[0067] Step 2: After the reactor is cooled to room temperature, it is filtered and dried at 80°C. The obtained powder is calcined at 500°C for 2h to obtain nickel oxide powder;

[0068] Step 3: Take 0.2 g of the above nickel oxide powder and ultrasonically disperse it in 120 mL of deionized water for 15 min;

[0069] Step 4: Add 1 mL of chloroauric acid aqueous solution (0.01 mol / L) and 8 mL of lysine aqueous solution (0.01 mol / L) to the suspension after ultrasonic dispersion, stir for 30 min, then add 12 mL of sodium borohydride aqueous solution (0.1 mol / L), continue stirring and modifying at 25 ° C for 40 min, collect the powder by centrifugation, wash the obtained powder with anhydrous ethanol and dry it to obtain a precursor of mesoporous nickel oxide;

[0070] Step 5: Calcine the obtained precursor at 300°C for 1 hour to obtain a nickel oxide-based gas-sensitive material.

[0071] Example 4

[0072] Step 1: Take 1g nickel chloride, 0.1g Cr(NO3)3 and 2g urea and add them into 60mL deionized water, stir magnetically for 20min to mix evenly, pour the resulting solution into a reactor, and hydroheat at 160℃ for 6h;

[0073] Step 2: After the reactor is cooled to room temperature, it is filtered and dried at 80°C. The obtained powder is calcined at 500°C for 2h to obtain nickel oxide powder;

[0074] Step 3: Take 0.18g of the above nickel oxide powder and ultrasonically disperse it in 120mL of deionized water for 15min;

[0075] Step 4: Add 1 mL of chloroauric acid aqueous solution (0.01 mol / L) and 8 mL of lysine aqueous solution (0.01 mol / L) to the suspension after ultrasonic dispersion, stir for 30 min, then add 12 mL of sodium borohydride aqueous solution (0.1 mol / L), continue stirring and modifying at 25 ° C for 40 min, collect the powder by centrifugation, wash the obtained powder with anhydrous ethanol and dry it to obtain a precursor of mesoporous nickel oxide;

[0076] Step 5: Calcine the obtained precursor at 300°C for 1 hour to obtain a nickel oxide-based gas-sensitive material.

[0077] Characterization and performance testing

[0078] Figure 1 This is a scanning electron microscope image of the nickel oxide-based gas-sensitive material prepared in Example 1; Figure 1 As shown, the prepared nickel oxide-based gas-sensitive material spherical particles have a particle size of less than 100 nm, and smaller modifier particles are dispersed on the surface.

[0079] Figure 2 From the isothermal adsorption-desorption curve and pore size distribution curve of the nickel oxide-based gas-sensitive material prepared in Example 1, it can be clearly seen that the synthesized spherical particles have a mesoporous structure with a pore size of approximately 5-30 nm, which will provide better assistance for the adsorption and transmission of the gas to be measured on the surface of the gas-sensitive semiconductor.

[0080] Test the sensitivity of nickel oxide-based gas-sensitive materials to 3-methyl-2-butene-1-thiol under different modification conditions: open the software during the test, set the test time to 3 minutes, the test voltage to 3.87V, insert the 4.7K resistor card, and then put the test board into the test bench. Keep the component stable for one minute. After one minute, drop the test liquid 3-methyl-2-butene-1-thiol on the addition table to fill the test cavity with test gas. After the component response is stable for one minute, remove the test gas and let the component voltage stabilize for one minute to reach about 90% of the level before the test. The test is completed. See the results. Figure 3 .

[0081] Figure 3The sensitivity results of nickel oxide-based gas-sensitive materials to 3-methyl-2-butene-1-thiol under different modification conditions, wherein pvp corresponds to the nickel oxide prepared in Example 1; 0.05Cr loading corresponds to the nickel oxide prepared in Example 2; 0.075Cr loading corresponds to the nickel oxide prepared in Example 3; 0.1Cr loading corresponds to the nickel oxide prepared in Example 4; Au-modified pvp corresponds to the nickel oxide-based gas-sensitive material prepared in Example 1; Au-modified 0.05Cr corresponds to the nickel oxide-based gas-sensitive material prepared in Example 2; Au-modified 0.075Cr corresponds to the nickel oxide-based gas-sensitive material prepared in Example 3; Au-modified 0.1Cr corresponds to the nickel oxide-based gas-sensitive material prepared in Example 4; Figure 3 It can be seen that by modifying nickel oxide, especially by modifying it with cadmium and gold, its sensitivity to 3-methyl-2-butene-1-thiol is improved, which well meets its application as a gas sensor material.

[0082] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a nickel oxide-based semiconductor gas-sensitive material, characterized in that: The following steps are involved: The nickel source, the additive, the urea and the water are mixed and subjected to a hydrothermal treatment to obtain a hydrothermal product; The hydrothermal product is subjected to a first calcination to obtain nickel oxide; The nickel oxide, water and a modifier are mixed and modified to obtain a precursor; The precursor is subjected to a second calcination to obtain a nickel oxide-based semiconductor gas-sensitive material; The additives include a binder and / or a metal compound; The modifying agents include chloroauric acid, lysine and sodium borohydride.

2. The preparation method according to claim 1, characterized in that: The nickel source includes nickel chloride; the binder includes one or more of PVP, PVA, CMC and PEG; and the metal compound includes one or more of cadmium nitrate, chromium nitrate, indium nitrate and silver nitrate.

3. The preparation method according to claim 1 or 2, characterized in that: The mass ratio of the nickel source, the additive, the urea and the water is 0.5-4:0.1-1:1-6:90-99.

4. The preparation method according to claim 3, characterized in that: The temperature of the hydrothermal treatment is 120-180° C., and the time is 4-12 hours.

5. The preparation method according to claim 1, characterized in that: The first calcination is carried out at a temperature of 300 to 800° C. and for a time of 2 to 4 hours.

6. The preparation method according to claim 1, characterized in that: The molar ratio of the nickel oxide to the modifier is (2-5):(0.5-2); the molar ratio of chloroauric acid, lysine and sodium borohydride in the modifier is (0.5-2.5):(1-12):(90-200); the modification temperature is 25-80°C and the modification time is 30-100 minutes.

7. The preparation method according to claim 1 or 6, characterized in that: The second calcination temperature is 200-500° C., and the time is 1-3 hours.

8. The nickel oxide-based semiconductor gas-sensitive material prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the nickel oxide-based semiconductor gas-sensitive material according to claim 8 in monitoring the odor of marijuana.

10. A cannabis gas sensor, characterized in that: The nickel oxide-based semiconductor gas-sensitive material according to claim 8 is used.

Images