阅读说明：本技术 一种石墨烯基气敏材料及其制备方法及其应用 (Graphene-based gas-sensitive material, and preparation method and application thereof ) 是由 矫维成 黄亦凡 王荣国 赫晓东 于 2020-11-16 设计创作，主要内容包括：本发明提供了一种石墨烯基气敏材料及其制备方法及其应用,其制备方法包括如下步骤：步骤S1,准备氧化石墨烯；步骤S2,采用水热法制备石墨烯和硫化锡的复合材料,使硫化锡片层在静电吸附作用下,在氧化石墨烯的表面结晶生长,同时,氧化石墨烯在水热作用下还原生成石墨烯。采用本发明技术方案,通过硫化锡和石墨烯的协同作用,在室温下可以快速吸附二氧化氮分子,具有极高的灵敏度,在室温下也可以快速脱附,有利于在短时间内进行多次气敏响应,且对除二氧化氮外其他气体几乎不产生响应；制备方法快速、简便,可重复,易于控制。(The invention provides a graphene-based gas-sensitive material, a preparation method and application thereof, wherein the preparation method comprises the following steps: step S1, preparing graphene oxide; step S2, preparing the composite material of graphene and tin sulfide by a hydrothermal method, so that a tin sulfide layer grows on the surface of graphene oxide in a crystallization manner under the action of electrostatic adsorption, and meanwhile, the graphene oxide is reduced to generate graphene under the action of hydrothermal. By adopting the technical scheme of the invention, through the synergistic effect of tin sulfide and graphene, nitrogen dioxide molecules can be quickly adsorbed at room temperature, the sensitivity is extremely high, the nitrogen dioxide molecules can be quickly desorbed at room temperature, multiple gas-sensitive responses can be favorably carried out in a short time, and the nitrogen dioxide molecules hardly generate responses to other gases except nitrogen dioxide; the preparation method is rapid, simple, repeatable and easy to control.)

1. A preparation method of a graphene-based gas-sensitive material is characterized by comprising the following steps: which comprises the following steps:

step S1, preparing graphene oxide;

step S2, preparing the composite material of graphene and tin sulfide by a hydrothermal method, so that a tin sulfide layer grows on the surface of graphene oxide in a crystallization manner under the action of electrostatic adsorption, and meanwhile, the graphene oxide is reduced to generate graphene under the action of hydrothermal.

2. The method for preparing the graphene-based gas-sensitive material according to claim 1, wherein: in the reaction of step S2, potassium stannate was used as the tin source, l-cysteine as the sulfur source, and CTAB as the linker.

3. The method for preparing the graphene-based gas-sensitive material according to claim 1, wherein: in the step S2, first dissolving CTAB in deionized water, adding graphene oxide, and performing ultrasonic dispersion to fully disperse the graphene oxide to obtain a graphene oxide dispersion solution; continuously stirring to ensure that the graphene oxide and CTAB are fully adsorbed; adding potassium stannate and l-cysteine, continuing stirring, then carrying out hydrothermal reaction, cooling, centrifuging and washing.

4. The method for preparing the graphene-based gas-sensitive material according to claim 3, wherein: the temperature of the hydrothermal reaction is 180-250 ℃.

5. The method for preparing the graphene-based gas-sensitive material according to claim 3, wherein: the stirring speed is 300-400 r/min, and the stirring time is 1-3 h.

6. The method for preparing the graphene-based gas-sensitive material according to claim 1, wherein: the mass ratio of the graphene oxide to the tin sulfide is 1: 20 to 160.

7. The method for preparing the graphene-based gas-sensitive material according to any one of claims 1 to 6, wherein: in step S1, oxidizing natural graphite with an oxidizing agent to generate oxygen-containing functional groups on the surface of the natural graphite, and then expanding and peeling the natural graphite to obtain graphene oxide.

8. A graphene-based gas-sensitive material characterized by: the graphene-based gas-sensitive material is prepared by the preparation method of the graphene-based gas-sensitive material as claimed in any one of claims 1 to 7.

9. Use of the graphene-based gas-sensitive material according to claim 8, wherein: the graphene-based gas-sensitive material is used for detecting nitrogen dioxide gas.

Technical Field

The invention belongs to the technical field of new materials, and particularly relates to a graphene-based gas-sensitive material, and a preparation method and application thereof.

Background

The detection of the nitrogen dioxide gas plays an important role in the aspects of environmental protection, industrial production, medical diagnosis and the like. The united states Environmental Protection Agency (EPA) has recognized that nitrogen dioxide gas at concentrations in excess of 100ppb can be harmful to humans. At present, the core gas-sensitive sensing material in the gas sensor for nitrogen dioxide is mainly semiconductor metal oxide. Such gas sensitive materials require a high sensing temperature, require heating in a room temperature environment, and thus are difficult to respond quickly. And the gas-sensitive material is difficult to desorb the target gas, and after one sensing reaction is carried out, the next sensing can be carried out only by carrying out a desorption reaction for a certain time in a high-temperature environment, so that the repeatability detection capability of the sensor is greatly limited. Moreover, the current gas sensitive materials are mainly used for detecting target gases with parts per million concentration (ppm level), and have low sensitivity, and are difficult to detect target gases with lower concentration (parts per billion concentration, ppb level). In addition, due to poor selectivity of the current sensor, other gases in the detection environment are easy to interfere with the sensor.

Disclosure of Invention

Aiming at the technical problems, the invention discloses a graphene-based gas-sensitive material, a preparation method and application thereof, and solves the problems that the existing sensor is poor in selectivity, and other gases in the detection environment are easy to interfere with the sensor.

In contrast, the technical scheme adopted by the invention is as follows:

a preparation method of a graphene-based gas-sensitive material comprises the following steps:

step S1, preparing graphene oxide;

step S2, preparing the composite material of graphene and tin sulfide by a hydrothermal method, so that a tin sulfide layer grows on the surface of graphene oxide in a crystallization manner under the action of electrostatic adsorption, and meanwhile, the graphene oxide is reduced to generate graphene under the action of hydrothermal.

The composite material obtained by the technical scheme can quickly adsorb nitrogen dioxide molecules at room temperature, has extremely high sensitivity to ppb-level nitrogen dioxide gas, can quickly react and recover, has good selectivity, and can meet the current gas-sensitive sensing requirement; can be rapidly desorbed at room temperature, has little response to other gases except nitrogen dioxide, and can be used for gas detection of the billionth concentration of nitrogen dioxide at room temperature. The gas-sensitive material has wide application prospect in gas detection under extremely low concentration. The preparation method of the material has the advantages of rapidness, simplicity, convenience, repeatability, easy control and the like.

As a further improvement of the invention, in the reaction of step S2, potassium stannate is used as a tin source, l-cysteine is used as a sulfur source, and CTAB is used as a linking agent.

As a further improvement of the invention, in step S2, first dissolving CTAB in deionized water, adding graphene oxide, and performing ultrasonic dispersion to fully disperse the graphene oxide to obtain a graphene oxide dispersion solution; continuously stirring to ensure that the graphene oxide and CTAB are fully adsorbed; adding potassium stannate and l-cysteine, continuing stirring, then carrying out hydrothermal reaction, cooling, centrifuging and washing.

As a further improvement of the invention, the temperature of the hydrothermal reaction is 180-250 ℃. Further, the temperature of the hydrothermal reaction is 200 ℃.

As a further improvement of the invention, the stirring speed is 300-400 r/min, and the stirring time is 1-3 h.

As a further improvement of the present invention, the mass ratio of the graphene oxide to the tin sulfide is 1: 20 to 160. Further, the mass ratio of the graphene oxide to the tin sulfide is 1: 140-160, or the mass ratio of the graphene oxide to the tin sulfide is 1: 25 to 30. When the mass ratio of the graphene oxide to the tin sulfide is 1: 140-160, and the obtained composite material is an n-type gas-sensitive material. The mass ratio of the graphene oxide to the tin sulfide is 1: 25-30, and the obtained composite material is a p-type gas-sensitive material. By adopting the technical scheme, the ratio of the graphene to the tin sulfide can be adjusted according to needs, and the gas-sensitive material can generate semiconductor p-n type conversion, so that different responses can be generated to nitrogen dioxide gas.

As a further improvement of the present invention, in step S1, natural graphite is oxidized by an oxidizing agent to generate oxygen-containing functional groups on the surface thereof, and then the graphene oxide is obtained by expansion exfoliation.

The invention also discloses a graphene-based gas-sensitive material which is prepared by adopting the preparation method of any one of the graphene-based gas-sensitive materials.

The invention also discloses an application of the graphene-based gas-sensitive material, and the graphene-based gas-sensitive material is used for detecting nitrogen dioxide gas. Further, the graphene-based gas-sensitive material is used for detecting nitrogen dioxide gas with ppb level content.

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

firstly, by adopting the technical scheme of the invention, tin sulfide and graphene materials are compounded by utilizing the unique gas-sensitive performance of tin sulfide and a hydrothermal synthesis method to prepare a room-temperature gas-sensitive material with high sensitivity, wherein the tin sulfide has extremely high adsorption energy on nitrogen dioxide gas and is used as an adsorption site of target gas; the graphene has a zero band gap structure, and provides a conductive path for a tin sulfide material in the composite material, so that charges on target gas can be rapidly transferred, and obvious resistance change is generated. The tin sulfide sheets are mutually stacked on the surface of the graphene, so that the specific surface area is higher, and the adsorption effect of gas is further increased. Through the synergistic effect of tin sulfide and graphene, nitrogen dioxide molecules can be quickly adsorbed at room temperature, the high sensitivity is realized, the desorption can be quickly realized at room temperature, multiple gas-sensitive responses can be favorably carried out in a short time, and the response to other gases except nitrogen dioxide is hardly generated.

Secondly, by adjusting the ratio of graphene to tin sulfide, the gas sensitive material can generate semiconductor p-n type conversion, and generate different responses to nitrogen dioxide gas. The material has extremely high sensitivity to ppb level nitrogen dioxide gas, can be quickly reacted and recovered, has good selectivity, and can meet the current gas-sensitive sensing requirements. And the material can generate conversion of sensing types at different compounding ratios, and generate different sensing responses to target gases.

Thirdly, the preparation method of the invention is rapid, simple, convenient, repeatable and easy to control.

Drawings

Fig. 1 is an SEM image of the graphene-based gas sensitive material obtained in example 1 of the present invention.

Fig. 2 is a dynamic curve of the gas-sensitive response of the graphene-based gas-sensitive material obtained in example 1 of the present invention to nitrogen dioxide.

Fig. 3 is a dynamic curve of the gas-sensitive response of the graphene-based gas-sensitive material obtained in example 2 of the present invention to nitrogen dioxide.

Fig. 4 is a graph of the sensing performance of the graphene-based gas-sensitive material obtained in example 2 of the present invention on nitrogen dioxide.

Detailed Description

Preferred embodiments of the present invention are described in further detail below.

Example 1

A graphene-based gas-sensitive material is prepared by the following steps:

(1) and preparing graphene oxide. And preparing the graphene oxide by adopting an improved Hummers method. The principle of the oxidation process is that a strong oxidant is adopted to oxidize natural graphite, so that oxygen-containing functional groups are generated on the surface of the natural graphite, and then the natural graphite is expanded and stripped to obtain graphene oxide.

(2) Ultrasonically dissolving 0.6mmol CTAB into 20ml of deionized water, adding 1mg of graphene oxide, and ultrasonically treating for 1h to fully disperse the graphene oxide. Stirring the solution for 2 hours at the speed of 300-400 r/min to enable the graphene oxide and CTAB to be fully adsorbed. Adding 1mmol of potassium stannate and 4mmol of l-cysteine, and stirring for 30 min.

Adding deionized water, preparing 40ml of the solution, pouring the solution into a 50ml reaction kettle, and carrying out hydrothermal reaction at 200 ℃ for 24 hours. After cooling to room temperature, centrifuging at 8000r/min for 10min, and washing until the supernatant is clear. And drying the precipitate at 60 ℃ for 24h to obtain the tin sulfide/graphene composite material, wherein the composite material is an n-type gas-sensitive material. The SEM image of the composite material is shown in figure 1, the dynamic curve of gas-sensitive response to nitrogen dioxide is shown in figure 2, and the composite material has high sensitivity to 1ppm nitrogen dioxide, has good sensitivity to ppb level nitrogen dioxide, has short recovery time, and can carry out multiple gas-sensitive responses in a short time.

Example 2

On the basis of embodiment 1, the difference of this embodiment is that 5mg of graphene oxide is added, the obtained composite material is a p-type gas-sensitive material, a dynamic curve of the gas-sensitive response of the material to nitrogen dioxide is shown in fig. 3, and the sensing performance of the material to nitrogen dioxide is shown in fig. 4. Therefore, the sensitivity to the nitrogen dioxide with the concentration of 1ppm reaches more than 45 percent, and the sensitivity to the nitrogen dioxide with the ppb content level is very good.

The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.