阅读说明：本技术 一种对甲醛气体具有特异性的敏感材料的制备方法 (Preparation method of sensitive material with specificity to formaldehyde gas ) 是由 卢靖 王亚军 徐灿 李翠艳 黄剑锋 于 2019-11-25 设计创作，主要内容包括：一种对甲醛气体具有特异性的敏感材料的制备方法,将氧化石墨烯悬浮液与含有柠檬酸、葡萄糖和SnCl<Sub>2</Sub>·2H<Sub>2</Sub>O的溶液混合,加入尿素与氨水,得到混合溶液；将混合溶液在微波/紫外/超声三合一反应仪中,采用控压模式进行微波水热反应,并进行超声处理,微波水热反应完成后,得到对甲醛气体敏感材料。本发明通过将SnO<Sub>2</Sub>与NG进行复合,通过调节反应介质组成及微波水热制备工艺,控制NG中吡啶氮、石墨氮、吡咯氮三种结构的浓度和分布状态,有利于甲醛分子与复合材料特异性结合,并随之产生强响应机制。本发明中SnO<Sub>2</Sub>与NG构成的异质结,可促进载流子分离和转移,有效提升材料的灵敏度和响应速度,制得的复合材料对甲醛气体具有高的选择性。(A method for preparing sensitive material with specificity to formaldehyde gas comprises mixing graphene oxide suspension with a solution containing citric acid, glucose and SnCl 2 ·2H 2 Mixing the solution of O, and adding urea and ammonia water to obtain a mixed solution; and (3) carrying out microwave hydrothermal reaction on the mixed solution in a microwave/ultraviolet/ultrasonic three-in-one reaction instrument in a pressure control mode, carrying out ultrasonic treatment, and obtaining the formaldehyde gas sensitive material after the microwave hydrothermal reaction is finished. The invention is realized by adding SnO 2 The composite material is compounded with NG, and the concentration and distribution state of pyridine nitrogen, graphite nitrogen and pyrrole nitrogen in the NG are controlled by adjusting the composition of a reaction medium and a microwave hydrothermal preparation process, so that the specific combination of formaldehyde molecules and the composite material is facilitated, and a strong response mechanism is generated. SnO in the present invention 2 The heterojunction formed by the material and the NG can promote the separation and transfer of carriers, effectively improve the sensitivity and response speed of the material, and prepare the materialThe obtained composite material has high selectivity to formaldehyde gas.)

1. A preparation method of a sensitive material with specificity to formaldehyde gas is characterized by comprising the following steps:

1) mixing the graphene oxide suspension with citric acidGlucose and SnCl₂·2H₂Mixing the solution of O, and then adding urea and ammonia water to obtain a mixed solution;

2) carrying out microwave hydrothermal reaction on the mixed solution in a microwave/ultraviolet/ultrasonic three-in-one reaction instrument in a pressure control mode, carrying out ultrasonic treatment simultaneously, and separating, washing and vacuum drying after the microwave hydrothermal reaction is finished to obtain a sensitive material which has specificity to formaldehyde gas and has specificity to the formaldehyde gas; wherein the temperature of the microwave hydrothermal reaction is 120-200 ℃, the pressure is 1.0-5.0 MPa, and the time is 60-200 min.

2. The method for preparing the sensitive material with specificity to the formaldehyde gas as claimed in claim 1, wherein in the step 1), the graphene oxide suspension is prepared by the following steps: and adding the graphene oxide into deionized water, and performing ultrasonic dispersion to obtain a graphene oxide suspension.

3. The method for preparing the sensitive material with specificity to formaldehyde gas as claimed in claim 2, wherein the ratio of graphene oxide to deionized water is 30 mg: 15mL, the power of ultrasonic dispersion is 400-600W, and the time is 4 h.

4. The method according to claim 1, wherein the sensitive material comprises citric acid, glucose and SnCl₂·2H₂The solution of O was prepared by the following procedure: mixing citric acid, glucose and SnCl₂·2H₂And adding O into deionized water, and stirring to dissolve to obtain a solution.

5. The method according to claim 4, wherein the sensitive material is selected from the group consisting of citric acid, glucose, SnCl₂·2H₂The ratio of O to deionized water was 1 mmol: 300 mg: 1-3 mmol: 15 mL.

6. According to the rightThe method for preparing the sensitive material with specificity to formaldehyde gas according to claim 5, wherein in the step 1), the graphene oxide and SnCl are mixed₂·2H₂The mass ratio of O is 1: 5-1: 25.

7. The method for preparing the sensitive material with specificity to the formaldehyde gas as claimed in claim 5, wherein in the step 1), the mass ratio of the graphene oxide to the urea is 1: 100-1: 300.

8. The method for preparing the sensitive material with specificity to the formaldehyde gas as claimed in claim 5, wherein the molar ratio of the urea to the ammonia water in the step 1) is 3:1-1: 3.

Technical Field

The invention relates to a preparation method of a sensitive material with specificity to formaldehyde gas.

Background

Tin dioxide is an N-type semiconductor gas-sensitive material with excellent performance, and has high sensitivity to oxidizing, reducing and volatile organic compound gases. But due to the universal surface contact-redox gas-sensitive mechanism, the selectivity and the anti-interference capability of the gas-sensitive material in a mixed atmosphere are required to be improved.

The nitrogen-doped graphene oxide serving as an important derivative of graphene has the characteristics of large specific surface area and strong adsorption capacity, and has great potential in the field of gas sensors because nitrogen is doped and more active adsorption sites exist in a carbon network.

Disclosure of Invention

The invention aims to provide a preparation method of a sensitive material with specificity to formaldehyde gas, the method has the advantages of simple preparation, convenient operation, strong controllability and the like, and the prepared composite material has a specific pyridine nitrogen/graphite nitrogen/pyrrole nitrogen ratio and has excellent selective sensitive response to formaldehyde gas.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of a sensitive material with specificity to formaldehyde gas comprises the following steps:

1) mixing the graphene oxide suspension with a solution containing citric acid, glucose and SnCl₂·2H₂Mixing the solution of O, and then adding urea and ammonia water to obtain a mixed solution;

2) carrying out microwave hydrothermal reaction on the mixed solution in a microwave/ultraviolet/ultrasonic three-in-one reaction instrument in a pressure control mode, simultaneously carrying out ultrasonic treatment, and separating, washing and vacuum drying after the microwave hydrothermal reaction is finished to obtain a sensitive material with specificity to formaldehyde gas; wherein the temperature of the microwave hydrothermal reaction is 120-200 ℃, the pressure is 1.0-5.0 MPa, and the time is 60-200 min.

In a further improvement of the present invention, in step 1), the graphene oxide suspension is prepared by the following process: and adding the graphene oxide into deionized water, and performing ultrasonic dispersion to obtain a graphene oxide suspension.

The further improvement of the invention is that the ratio of graphene oxide to deionized water is 30 mg: 15mL, the power of ultrasonic dispersion is 400-600W, and the time is 4 h.

The invention is further improved in that the composition contains citric acid, glucose and SnCl₂·2H₂The solution of O was prepared by the following procedure: mixing citric acid, glucose and SnCl₂·2H₂And adding O into deionized water, and stirring to dissolve to obtain a solution.

The invention further improves the method that citric acid, glucose and SnCl₂·2H₂The ratio of O to deionized water was 1 mmol: 300 mg: 1-3 mmol: 15 mL.

The further improvement of the invention is that in the step 1), the graphene oxide and SnCl are mixed₂·2H₂The mass ratio of O is 1: 5-1: 25.

The method is further improved in that in the step 1), the mass ratio of the graphene oxide to the urea is 1: 100-1: 300.

The invention is further improved in that in the step 1), the molar ratio of the urea to the ammonia water is 3:1-1: 3.

Compared with the prior art, the invention has the beneficial effects that:

the invention is realized by adding SnO₂The composite material is compounded with NG, and the concentration and distribution state of pyridine nitrogen, graphite nitrogen and pyrrole nitrogen in the NG are controlled by adjusting the composition of a reaction medium and a microwave hydrothermal preparation process, so that the specific combination of formaldehyde molecules and the composite material is facilitated, and a strong response mechanism is generated. The ammonia water is added in the invention, so that the target product has high pyridine nitrogen content, and the material has the characteristic of high selectivity to formaldehyde gas. SnO in the present invention₂The heterojunction formed by the material and the NG can promote the separation and transfer of current carriers, effectively improve the sensitivity and response speed of the material, and the prepared composite material has high selectivity on formaldehyde gas.

Drawings

FIG. 1 is a SnO prepared according to example 2 of the present invention₂XRD pattern of/NG powder;

FIG. 2 is a SnO prepared according to example 2 of the present invention₂Raman spectrum of NG powder;

FIG. 3 is a SnO prepared according to example 2 of the present invention₂Selectivity profile of/NG powder to 100ppm of different gases.

Detailed Description

The present invention will be described in detail with reference to the accompanying drawings.

The invention provides a preparation method of a sensitive material with specificity to formaldehyde gas, which comprises the following steps:

1) weighing 30mg of graphene oxide, adding the graphene oxide into 15mL of deionized water, and performing ultrasonic dispersion with the ultrasonic power of 80-100W for 4h to obtain GO suspension A;

2) adding 1mmol of citric acid, 300mg of glucose and 1-3 mmol of SnCl₂·2H₂Adding O into 15mL of deionized water, and violently stirring on a magnetic stirrer until all soluble substances are dissolved to obtain a solution B;

3) mixing suspension A with solution B to make GO and SnCl₂·2H₂The mass ratio of O is 1: 5-1: 25, then adding urea and ammonia water according to a certain proportion to enable the mass ratio of GO to urea to be 1: 100-1: 300, namely the mass of urea to be 3-9g, and enabling the molar ratio of urea to ammonia water to be 3:1-1:3, namely the volume of ammonia water to be 0.7-17.3 mL, so as to obtain a mixed solution C;

4) and then transferring the mixed solution C into a reaction kettle, installing the reaction kettle into a microwave/ultraviolet/ultrasonic three-in-one reaction instrument, performing microwave hydrothermal reaction in a pressure control mode, performing ultrasonic treatment simultaneously in the reaction, wherein the ultrasonic power is 50-300W, and providing energy accompanied by ultrasonic during the microwave hydrothermal reaction. Controlling the hydrothermal temperature at 120-200 ℃, controlling the hydrothermal pressure at 1.0-5.0 MPa, and controlling the reaction time at 60-200 min;

5) after the reaction is completed, cooling the kettle to room temperature, taking out the product, performing centrifugal separation, respectively cleaning the product with deionized water and absolute ethyl alcohol, and finally performing vacuum drying to obtain the final product of tin dioxide composite nitrogen-doped graphene oxide (SnO)₂/NG) composite material.

The invention prepares II by a microwave hydrothermal methodThe tin oxide/nitrogen-doped graphene oxide composite material (SnO) with a specific structure is obtained by precisely controlling the nitrogen doping amount and regulating and controlling the pressure environment of microwave hydrothermal₂/NG)。

The following are specific examples.