阅读说明：本技术 一种用于海鲜新鲜度检测的半导体气体传感器的制备方法 (Preparation method of semiconductor gas sensor for detecting freshness of seafood ) 是由 闫文君 张尔攀 凌敏 于 2020-12-31 设计创作，主要内容包括：本发明公开了一种用于海鲜新鲜度检测的半导体气体传感器的制备方法,本发明开发了一种对三甲胺气体具有超快响应和良好选择性的半导体核壳结构纳米材料Co-3O-4@ZnO,该材料通过氧化核壳结构ZIF67@ZIF8制得,具有多孔性和空心结构；将Co3O4@ZnO纳米材料与松油醇混合研磨均匀,形成有一定粘度的浆料；采用基于MEMS技术的集成有微加热器的硅基底叉指电极芯片作传感器芯片,将上述制备的浆料涂覆于叉指电极中间位置,获得性能稳定的传感器件。本发明制备的传感器检测三甲胺气体时具有良好的选择性,不受乙醇、氨气等干扰,且受环境湿度影响极小,响应迅速、恢复彻底。(The invention discloses a preparation method of a semiconductor gas sensor for detecting seafood freshness, and develops a semiconductor core-shell structure nano material Co with ultrafast response and good selectivity to trimethylamine gas 3 O 4 @ ZnO, which is prepared by oxidizing a core-shell structure ZIF67@ ZIF8, and has a porous and hollow structure; mixing and grinding the Co3O4@ ZnO nano material and terpineol uniformly to form slurry with certain viscosity; and coating the prepared slurry on the middle position of the interdigital electrode to obtain the sensor device with stable performance. The sensor prepared by the invention has good selectivity when detecting trimethylamine gas, is not interfered by ethanol, ammonia gas and the like, is slightly influenced by the environmental humidity, and has quick response and thorough recovery.)

1. A preparation method of a semiconductor gas sensor for detecting freshness of seafood is characterized by comprising the following steps:

step one, respectively preparing a cobalt acetate dihydrate aqueous solution and a dimethyl imidazole aqueous solution, taking a zinc acetate dihydrate aqueous solution and a dimethyl imidazole aqueous solution, mixing the two solutions in equal volumes, standing the obtained mixed solution at room temperature for 30min, performing centrifugal separation on precipitates in the mixed solution, washing, and drying under vacuum conditions to obtain a product ZIF 67;

step two, taking 5-20 mg of the product obtained in the step 1, and dispersing the product into 4-6 mL of 1.9mol/L dimethyl imidazole aqueous solution to obtain a mixed solution A;

step three, adding a certain amount of zinc acetate dihydrate water solution with the concentration of 120mmol/L into the mixed solution A obtained in the step 2, wherein the volume ratio of the zinc acetate dihydrate water solution to the solution A is 1:1, fully mixing uniformly, and then placing for 30min at room temperature; centrifuging the precipitate in the mixed solution, washing, and drying in vacuum to obtain [email protected] ZIF8 with a core-shell nano structure;

step four, calcining the ZIF core-shell structure nano material prepared in the step 3 in air at the temperature of 350-450 ℃ for 2h at the heating rate of 1-2 ℃/min to obtain porous hollow Co₃O₄@ ZnO core-shell structure;

step five, mixing the Co prepared in the step 4₃O₄Grinding and uniformly mixing the @ ZnO core-shell structure nano material and terpineol to form viscous slurry; the preparation method comprises the steps of adopting a silicon substrate interdigital electrode chip integrated with a micro-heater based on an MEMS technology as a sensor chip, coating the prepared slurry on the middle position of an interdigital electrode, removing an organic solvent terpineol by using the integrated micro-heater, and preparing a sensitive material Co₃O₄@ ZnO semiconductor gas sensingThe sensor has ultrasensitive selection specificity to trimethylamine gas and can be used for detecting the freshness of seafood.

2. The preparation method of the semiconductor gas sensor for seafood freshness detection, as claimed in claim 1, is characterized in that the synthesis of the [email protected] ZIF8 core-shell structure takes ZIF67 as a core and ZIF8 as an outer shell, the ZIF67 is synthesized in step 1, and the ZIF8 shell is wrapped on the surface of ZIF67 in step three.

3. The method for preparing a semiconductor gas sensor for detecting the freshness of seafood as claimed in claim 1, wherein the concentration of the cobalt acetate dihydrate solution in the first step and the third step is 120 mmol/L; the concentration of the dimethyl imidazole aqueous solution is 6 mol/L.

4. The method for preparing the semiconductor gas sensor for detecting the freshness of the seafood as claimed in claim 3, wherein the amounts of the zinc acetate dihydrate aqueous solution and the dimethyl imidazole aqueous solution are respectively 8-10 mL.

Technical Field

The invention relates to a semiconductor gas sensor, in particular to a semiconductor gas sensor for detecting the freshness of seafood.

Background

The seafood product is extremely easy to rot, trimethylamine gas can be generated when the seafood product is placed for a long time, and the freshness of the seafood product can be detected through the concentration of the trimethylamine gas. At present, the trimethylamine semiconductor gas sensor has poor selectivity, high detection concentration and long response/recovery time, and the application of the trimethylamine semiconductor gas sensor is limited.

Disclosure of Invention

Aiming at the defects of the prior art, the invention develops a semiconductor gas-sensitive material with ultrahigh sensitivity and selectivity specificity to trimethylamine gas through the design of core-shell structure nano materials, and prepares a semiconductor gas sensor for detecting the freshness of seafood.

A semiconductor gas sensor for detecting the freshness of seafood specifically comprises the following steps:

step one, respectively preparing a cobalt acetate dihydrate aqueous solution and a dimethyl imidazole aqueous solution with certain concentrations, respectively taking a certain amount of a zinc acetate dihydrate aqueous solution and a certain amount of a dimethyl imidazole aqueous solution, uniformly mixing the two solutions in equal volumes, standing the obtained mixed solution at room temperature for 30min, centrifugally separating precipitates in the mixed solution, washing, and drying under vacuum conditions to obtain a product ZIF 67;

step two, taking a certain amount of the product obtained in the step 1, and dispersing the product into a dimethyl imidazole aqueous solution to obtain a mixed solution A;

step three, preparing a zinc acetate dihydrate aqueous solution with a certain concentration, adding the zinc acetate dihydrate aqueous solution into the mixed solution A obtained in the step 2, mixing the zinc acetate dihydrate aqueous solution and the mixed solution A in equal volume, fully mixing the two solutions uniformly, and then placing the mixture at room temperature for 30 min. And (3) carrying out centrifugal separation, washing and vacuum drying on the precipitate in the mixed solution to obtain [email protected] ZIF8 with a core-shell nano structure.

Step four, calcining the ZIF core-shell structure nano material prepared in the step 3 in air to obtain porous hollow Co₃O₄@ ZnO core-shell structure.

Step five, mixing the Co prepared in the step 4₃O₄Grinding and uniformly mixing the @ ZnO core-shell structure nano material and terpineol to form slurry with certain viscosity; the preparation method comprises the steps of adopting a silicon substrate interdigital electrode chip integrated with a micro-heater based on an MEMS technology as a sensor chip, coating the prepared slurry on the middle position of an interdigital electrode, removing an organic solvent terpineol by using the integrated micro-heater, and preparing a sensitive material Co₃O₄@ ZnO semiconductor gas sensor having ultrasensitive selectivity specificity for trimethylamine gasAnd can be used for detecting the freshness of seafood.

Preferably, the synthesis of the [email protected] ZIF8 core-shell structure takes ZIF67 as a core and ZIF8 as an outer shell, ZIF67 is synthesized in step 1, and a ZIF8 shell is wrapped on the surface of ZIF67 in step three.

Preferably, the concentration of the cobalt acetate dihydrate aqueous solution in the first step and the third step is 120 mmol/L; the concentration of the dimethyl imidazole aqueous solution is 6 mol/L.

Preferably, the amount of the zinc acetate dihydrate aqueous solution and the amount of the dimethyl imidazole aqueous solution are respectively 8-10 mL.

Has the advantages that:

1. the gas sensor prepared by the invention has good selective detection performance on trimethylamine gas;

2. the gas sensor prepared by the invention has ultra-rapid detection characteristic on low-concentration trimethylamine gas and has higher sensitivity;

3. when the gas sensor prepared by the invention is used for detecting low-concentration trimethylamine gas, the influence of high-concentration formaldehyde, ethanol, ammonia gas and other gases is hardly influenced.

4. When the gas sensor prepared by the invention is used for detecting trimethylamine gas, the influence of the environmental humidity is extremely small.

Drawings

FIG. 1 shows Co prepared in example 1₃O₄@ ZnO core-shell structure nano material;

FIG. 2 is a graph showing the sensitivity of the gas sensor prepared in example 1 to trimethylamine, formaldehyde, ethanol and ammonia gas;

FIG. 3 is a graph showing the sensitivity response/recovery curves of the gas sensor prepared in example 1 to various concentrations of trimethylamine gas;

FIG. 4 is a graph showing the sensitivity response/recovery of the gas sensor prepared in example 1 to trimethylamine gas at different humidities;

FIG. 5 is a graph showing the sensitivity response/recovery of the gas sensor prepared in example 1 to 33ppm of trimethylamine gas;

fig. 6 is a graph showing the sensitivity response/recovery curves of the gas sensor prepared in example 2 to various concentrations of trimethylamine gas.

Detailed Description

Example 1

1) Respectively preparing a cobalt acetate dihydrate aqueous solution with the concentration of 120mmol/L and a dimethyl imidazole aqueous solution with the concentration of 6mol/L, respectively taking 10mL of a zinc acetate dihydrate aqueous solution and the dimethyl imidazole aqueous solution, respectively, fully and uniformly mixing the two solutions in equal volumes, standing the obtained mixed solution at room temperature for 30min, centrifugally separating precipitates in the mixed solution, washing, and drying under vacuum conditions to obtain a product ZIF 67;

2) taking 20mg of the product obtained in the step 1, and dispersing the product into 5mL of 1.9mol/L dimethyl imidazole aqueous solution to obtain a mixed solution A;

3) and (3) adding a zinc acetate dihydrate water solution with the concentration of 120mmol/L into the mixed solution A obtained in the step (2), wherein the volume ratio of the zinc acetate dihydrate water solution to the solution A is 1:1, fully mixing uniformly, and then placing at room temperature for 30 min. And (3) carrying out centrifugal separation, washing and vacuum drying on the precipitate in the mixed solution to obtain [email protected] ZIF8 with a core-shell nano structure.

4) Calcining the ZIF core-shell structure nano material prepared in the step 3 in air at 400 ℃ for 2h at the heating rate of 1 ℃/min to obtain porous hollow Co₃O₄@ ZnO core-shell structure.

5) Mixing the Co prepared in the step 4₃O₄The @ ZnO core-shell structure nano material and terpineol are mixed according to the mass ratio of 5: 1 grinding and uniformly mixing to form slurry with certain viscosity; the preparation method comprises the steps of adopting a silicon substrate interdigital electrode chip integrated with a micro-heater based on an MEMS technology as a sensor chip, coating the prepared slurry on the middle position of an interdigital electrode, removing an organic solvent terpineol by using the integrated micro-heater, and preparing a sensitive material Co₃O₄The @ ZnO semiconductor gas sensor has ultrasensitive selectivity specificity to trimethylamine gas and can be used for detecting freshness of seafood.

Co prepared in example 1₃O₄The @ ZnO core-shell structure is shown in figure 1, the core is Co₃O₄The outer shell is ZnO;

the sensitivity of the gas sensor prepared in example 1 to trimethylamine, formaldehyde, ethanol and ammonia gas is compared as shown in fig. 2, and the sensor has good selection specificity to low-concentration trimethylamine gas;

the sensitivity response/recovery curve of the gas sensor prepared in example 1 to trimethylamine gases with different concentrations is shown in fig. 3, when contacting with the trimethylamine gas, the sensor current rises rapidly and reaches a stable state rapidly, and the response time for detecting the trimethylamine gases with different concentrations is about 3 s; after trimethylamine gas is removed, the current of the sensor is rapidly reduced to an initial value, and the recovery time after detecting the trimethylamine gas with different concentrations is about 2 s; the sensitivity to 33ppm trimethylamine gas is about 42, and when the concentration exceeds 33ppm, the sensitivity value tends to be saturated.

The sensitivity response/recovery curve of the gas sensor prepared in example 1 to 33ppm of trimethylamine gas at different humidities of 60%, 70% and 80% is shown in fig. 4, and the ambient humidity has little influence on the sensitivity of the sensor at an operating temperature of 250 c, and the fluctuation value of the sensitivity is about 6%.

The repeatability sensitive response/recovery curve of the gas sensor prepared in example 1 to 33ppm trimethylamine gas is shown in fig. 5, the repeatability of the sensor to detect trimethylamine gas is good, the cross sensitivity to ethanol and ammonia gas is weak, and the sensor is hardly affected by ethanol and ammonia gas when detecting trimethylamine.

Example 2

This example is similar to example 1 except that 5mg of the product of step 1 in step 2) was dispersed in 5mL of a 1.9mol/L aqueous solution of dimethylimidazole to obtain a mixed solution A.

The sensitivity response/recovery curves of the gas sensor prepared in example 2 to various concentrations of trimethylamine gas are shown in fig. 6.

Example 3

The embodiment is similar to embodiment 1, except that step 4) is to calcine the ZIF core-shell structure nano material prepared in step 3 in air at 380 ℃ for 2h, and the heating rate is 1.5 ℃/min to obtain porous hollow Co₃O₄@ ZnO core-shell structure.

The invention adopts a static gas distribution method to measure the sensitive characteristic of the semiconductor sensorThe sensitivity in the detection of a gas is defined as (I)_s-I₀)/I₀Wherein, I_sIndicating the current value of the sensor in a gas to be detected with a certain concentration_，I₀Indicating the current value of the sensor in the background gas.