WO2023272666A1 - 一种聚合物修饰石墨烯复合材料及其传感器与应用 - Google Patents

一种聚合物修饰石墨烯复合材料及其传感器与应用 Download PDF

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WO2023272666A1
WO2023272666A1 PCT/CN2021/103886 CN2021103886W WO2023272666A1 WO 2023272666 A1 WO2023272666 A1 WO 2023272666A1 CN 2021103886 W CN2021103886 W CN 2021103886W WO 2023272666 A1 WO2023272666 A1 WO 2023272666A1
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composite material
polymer
graphene
gas
graphene composite
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PCT/CN2021/103886
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French (fr)
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王艳艳
吴哲昆
应舒杨
黄曼曼
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苏州大学
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/182—Graphene
    • C01B32/194—After-treatment
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G39/00—Compounds of molybdenum
    • C01G39/06—Sulfides
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
    • C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Definitions

  • the invention belongs to gas sensor technology, in particular to a polymer-modified graphene composite material and its sensor and application.
  • the invention discloses a polymer-modified graphene composite material, that is, polypyrrole is modified on the surface of the molybdenum disulfide/graphene quantum dot/graphene oxide ternary composite material.
  • the composite material of the invention has more active sites, good thermal stability and chemical stability, and is beneficial to gas adsorption.
  • the corresponding morphology, crystal phase and composition of the composite material were characterized.
  • the research results showed that the polypyrrole modified MoS 2 /rGO/GQDs composite material was better than the MoS 2 /rGO/GQDs composite material in terms of response sensitivity and detection limit. materials, MoS 2 /rGO and MoS 2 /GQDs materials are significantly improved, and have excellent repeatability and selectivity.
  • the invention discloses a polymer-modified graphene composite material, which comprises molybdenum disulfide, graphene, graphene quantum dots and a polymer.
  • the present invention forms a graphene composite material with molybdenum disulfide, graphene, and graphene quantum dots, and then modifies the polymer to obtain a polymer-modified graphene composite material, which has more active sites, is beneficial to the adsorption of gases, and is more More chemically adsorbed oxygen participates in the reaction, so that electrons are extracted by NO2 gas faster, so that the polypyrrole-modified MoS2/rGO/GQDs composite material can fully contact and react with gas molecules while improving the electrical conductivity.
  • the composite material has abundant pores. Providing more reaction sites for the adsorption of molecules is an effective means to improve the gas-sensing response performance of materials.
  • the invention discloses the application of the polymer-modified graphene composite material in the preparation of gas sensors, especially the application in the preparation of nitrogen dioxide sensors.
  • the invention discloses a gas sensor, which comprises a substrate and a gas-sensing material, and the gas-sensing material is the above-mentioned polymer-modified graphene composite material.
  • the substrates are existing products, such as interdigitated electrodes.
  • the inventiveness of the present invention lies in compounding new gas-sensitive materials on the existing substrates to obtain a new sensor with excellent nitrogen dioxide detection performance.
  • the invention discloses a preparation method of the above-mentioned gas sensor.
  • the mixture of molybdenum disulfide, graphene oxide, graphene quantum dots and water is heated and reacted to obtain a graphene composite material; Finally, the polymer is modified on the surface of the graphene composite to obtain a gas sensor.
  • graphene is reduced graphene oxide (rGO); graphene quantum dots (GQDs) are prepared by hydrothermal method, and flower-shaped dots are prepared by using sodium molybdate and thiourea as molybdenum and sulfur sources MoS 2 , using the existing improved Hummers method to prepare GO, using MoS 2 , GO and GQDs as raw materials, using hydrothermal method to prepare MoS 2 /rGO/GQDs composite material, and then using pyrrole in situ gas phase redox modification method
  • the prepared polypyrrole-modified MoS2/rGO/GQDs composite material is the product of the present invention. It was further prepared as a sensor, and the response characteristics of the sensor to NO 2 gas at room temperature were explored.
  • benzopyrene is used as a raw material to obtain graphene quantum dots through nitration, freezing, alkali etching and thermal reaction.
  • sodium molybdate dihydrate and thiourea are used as raw materials to obtain molybdenum disulfide through hydrothermal reaction.
  • the temperature of the hydrothermal reaction is 160-220° C., and the time is 15-25 hours.
  • the mixture of molybdenum disulfide, graphene oxide, graphene quantum dots, and water is heated and reacted to obtain a graphene composite material; then the polymer is modified on the surface of the graphene composite material to obtain a polymer-modified graphene composite material. Specifically, centrifugation is performed after the heating reaction, and the thick liquid in the lower layer is dried to obtain a graphene composite material.
  • the temperature of the heating reaction is 180-220° C., and the time is 10-15 hours.
  • the mass ratio of molybdenum disulfide, graphene quantum dots and graphene oxide is (3-25):(0.8-1.2):1, preferably (5-15):1:1.
  • the polymer is polypyrrole; the pyrrole is used as a raw material, and the gas-phase polymerization is carried out on the surface of the graphene composite material to obtain the polymer-modified graphene composite material.
  • iron salt is used as an oxidant for gas-phase polymerization; before gas-phase polymerization, the graphene composite material is subjected to surface treatment, including plasma treatment, soaking in ammonium persulfate aqueous solution, and potassium hydroxide aqueous solution.
  • the present invention adopts the hydrothermal method to prepare the GQDs dispersion liquid, and then adopts the simple hydrothermal method to prepare the MoS 2 /rGO/GQDs composite material, and transfers the MoS 2 /rGO/GQDs composite material dispersion liquid to the fork
  • a composite material sensor is prepared, and then pyrrole is used as a raw material to carry out gas phase polymerization on the surface of the MoS 2 /rGO/GQDs composite material to obtain a polymer-modified graphene composite material.
  • the test results show that when the NO 2 gas concentration is 50 ppm, the MoS 2 /rGO/GQDs composite gas sensor has a response value of 23.2%, and the polymer-modified graphene composite material of the present invention as a sensor of the gas-sensing material reaches 30.9%.
  • MoS 2 /rGO MoS 2 /GQDs and MoS 2 /rGO/GQDs, it is significantly improved, and has excellent repeatability and selectivity.
  • Figure 2 is a SEM image: (a) MoS 2 /rGO/GQDs-1; (b) MoS 2 /rGO/GQDs-2; (c) MoS 2 /rGO/GQDs-3; (d) MoS 2 /rGO/ GQDs-4; (e) MoS 2 /rGO/GQDs-5; (f) MoS 2 prepared by hydrothermal method.
  • Figure 3 is a SEM image of the interdigitated electrodes.
  • Figure 4 shows the response curves of MoS 2 /rGO/GQDs composite gas sensors with different mass ratios to 5 ppm NO 2 .
  • Figure 5 shows the repeatability test of polypyrrole-modified MoS 2 /rGO/GQDs-3 composite gas sensor for 5 ppm NO 2 .
  • Fig. 6 is the selectivity test of polypyrrole modified MoS 2 /rGO/GQDs-3 composite gas sensor.
  • Example 1 Polypyrrole-modified graphene composite material preparation of graphene quantum dots (GQDs), the experimental steps are as follows: Weigh 1 g of benzopyrene into a flask, add 80 ml of HNO3 solution (mass concentration 65%), Place it at 80 °C for 12 h to complete the nitration reaction, take out the flask and let it cool naturally, then filter the product with deionized water until the filtrate becomes colorless to obtain the product 1,3,6-trinitro Pyrene; the above product 1,3,6-trinitropyrene was freeze-dried at -52 °C for 12 h and turned into a foam, and then 1.5 g was weighed in 300 ml of NaOH solution with a concentration of 2 mol/l, Routine ultrasonication for 3 hours, followed by magnetic stirring for 5 hours, then poured into a reaction kettle, placed in an oven, and reacted at 200 °C for 8 hours, after cooling to room temperature, added deionized water, and
  • Figure 1 shows that there are many nano-dot-shaped particles with a radius ranging from tens of nanometers and a height of several nanometers, similar to a single-layer disk rather than a sphere.
  • Molybdenum disulfide preparation the process is as follows: Weigh 1.21 g of sodium molybdate dihydrate and 2.36 g of thiourea in a beaker, add water to make a 40 ml solution, stir for 3 hours, and react at 200°C for 18 hours; the reaction is over Naturally cool to room temperature, suck out the yellow supernatant with a dropper, wash the bottom precipitate with ethanol and deionized water, filter and transfer the filter cake to a vacuum drying oven, and dry at 60 °C for 8 h to obtain MoS 2 powder.
  • Graphene oxide was prepared by the improved Hummers method, for example: at room temperature, put 2 g of natural graphite into a three-neck flask, then add 50 ml of concentrated nitric acid (mass concentration 65%), stir for 30 min, and then add 1 g of sodium nitrate, stirred for 2 h under ice bath. Within half an hour, a total of 7.3 g of potassium permanganate was added three times, kept at 35 °C and stirred for 2 h, and the solution turned yellowish brown. Add 80 ml of deionized water to the solution and keep it for 30 min, during which the temperature of the solution will rise sharply.
  • the above-mentioned MoS 2 powder, GQDs solution, and GO dispersion were used to prepare graphene composite materials, specifically: weigh 75 mg of molybdenum disulfide powder, add it to 25 ml of deionized water, add 25 ml of GO solution (1mg /ml) and 25 ml GQDs solution (1mg/ml) (molybdenum disulfide, graphene quantum dots, graphene oxide mass ratio is 3:1:1), conventional ultrasonic dispersion for 3 h followed by stirring for 5 h to obtain a mixed solution, Transfer the mixed solution to a reaction kettle and react at 200 °C for 12 h. After the reaction, it was naturally cooled to room temperature.
  • the volumes of the GQDs solution and the GO dispersion were replaced to obtain molybdenum disulfide, graphene quantum dots, and graphene oxide mass ratios of 5:1:1, 10:1:1, 15:1:1 , 25:1:1, and the rest remain unchanged, the obtained products are MoS 2 /rGO/GQDs-2, MoS 2 /rGO/GQDs-3, MoS 2 /rGO/GQDs-4, MoS 2 /rGO/GQDs- 5.
  • Sheet-like graphene provides sites for the growth of molybdenum disulfide and affects its agglomeration, thereby affecting the performance of gas-sensing materials.
  • Figure 2 is the SEM image of the MoS 2 /rGO/GQDs composite material and molybdenum disulfide. It can be observed Many wrinkled graphene sheets are stacked together, and MoS 2 nanoflowers and small particles of GQDs are distributed on the exposed active sites of the graphene sheets. The content of MoS2 in the material increases accordingly, resulting in agglomeration, which is not conducive to the adsorption of gas molecules.
  • the MoS 2 /rGO/GQDs composite was conventionally treated with oxygen plasma for 10 min, then soaked in 1 mmol/L APS (ammonium persulfate) aqueous solution for 2 h, and dried in an oven to form a single amino group.
  • APS ammonium persulfate
  • Comparative example 1 Prepare MoS 2 /GQDs composite material by using the above MoS 2 powder and GQDs solution, specifically: weigh 75 mg of molybdenum disulfide powder, add it to 25 ml of deionized water, add GQDs solution (two The mass ratio of molybdenum sulfide and graphene quantum dots is 10:1), conventional ultrasonic dispersion for 3 h followed by stirring for 5 h to obtain a mixed solution, which was transferred to a reactor and reacted at 90°C for 12 h, and the reaction ended naturally Cool to room temperature, remove the supernatant liquid with a straw, add deionized water, pour it into a centrifuge tube, centrifuge at a speed of 10,000 rpm/min for 5 min, and centrifuge and dilute for 5 times to obtain a thick liquid at the bottom. It was placed in the refrigerator to freeze until it was ice cube-like, and then transferred to a freeze-drying box for 16 h to obtain a
  • MoS 2 powder and GO dispersion were used to prepare MoS 2 /rGO composite materials, specifically: weigh 75 mg of molybdenum disulfide powder, add it to 25 ml of deionized water, add GO solution (molybdenum disulfide, molybdenum disulfide, Graphene oxide mass ratio is 10:1), conventional ultrasonic dispersion for 3 h followed by stirring for 5 h to obtain a mixed solution, the mixed solution was transferred to the reactor, reacted at 200 °C for 12 h, and naturally cooled to room temperature after the reaction was completed. The black precipitate was centrifuged, washed with deionized water and ethanol, and dried under vacuum at 80°C to obtain the MoS 2 /rGO composite material.
  • the SEM image of the existing interdigitated electrode is shown in Figure 3. Stick it on the metal base and conduct it with a wire, and then drop-coat 3 ⁇ L of gas-sensitive material water dispersion (concentration: 1 mg/ml) on the interdigitated electrode. After airing and vacuum drying, the sensor was obtained.
  • the gas sensitive material is MoS 2 /rGO/GQDs composite material, MoS 2 /rGO composite material, MoS 2 /GQDs composite material, MoS 2 material, rGO material or GQDs composite material.
  • Example 2 sensor use the same interdigitated electrode as in Comparative Example 1, stick it on the metal base and conduct it with a wire, and then add 3 ⁇ L MoS 2 /rGO/GQDs composite water dispersion (concentration: 1 mg/ml)
  • the MoS 2 /rGO/GQDs composite was treated with oxygen plasma for 10 min, and then soaked in 1 mmol/L APS (ammonium persulfate) aqueous solution for 2 h, dried in an oven to form a monomolecular layer of amino groups on the surface of the MoS 2 /rGO/GQDs composite, and then placed in 20 mmol/L KOH aqueous solution for 8 h, then dried, and then transferred to 20 mmol/L FeCl3 aqueous solution for 12 h, then dried, then dropwise added 0.1 ml of pyrrole solution to the bottom of the reactor liner, transferred the interdigitated electrode with the MoS 2 /rGO/GQDs composite
  • Comparative Example 2 The above-mentioned MoS 2 powder, GQDs solution, and GO dispersion liquid calcining method were used to prepare graphene composite materials, specifically: 75 mg of molybdenum disulfide powder was mixed with GO and GQDs (molybdenum disulfide, graphene quantum dots , graphene oxide mass ratio is 10:1:1, added in the form of concentrated solution), conventionally ground and placed in a tube furnace, raised from room temperature to 350°C at 5°C per minute, kept for 1 hour, and cooled naturally to obtain R-MoS 2 /rGO/GQDs composite material, according to the method of Example 2, replace the MoS 2 /rGO/GQDs composite material with R-MoS 2 /rGO/GQDs composite material to obtain a comparison sensor, for 5 ppm NO 2 gas The response is 3.5% (sensor preparation and test method are the same as embodiment).
  • Embodiment 3 The detection of NO 2 gas is carried out at room temperature, and the gas sensor is in a closed space during the test, effectively isolating the external environment. NO 2 gas is used as the detection gas, and air is used to dilute the NO 2 to obtain different concentrations of the gas to be tested.
  • the test voltage is set to 5 mV, and the precise current information collected by Agilent test instruments is integrated into an IV diagram, from which the resistance value of the gas-sensitive material is calculated.
  • the background gas is fed for 100 s to keep the output current in a stable range, and then the background gas and NO 2 gas are fed in at a certain ratio.
  • the Agilent instrument will detect the current value of the device in real time, and the change of the current Calculate the change of resistance and then calculate the response value S (%) of the sensor.
  • the calculation formula is as follows: .
  • R0 is the initial resistance of the gas-sensing material under background gas
  • R is the real-time resistance value of the gas - sensing material exposed to NO2 gas
  • Figure 4 shows the response of MoS 2 /rGO/GQDs composites to 5 ppm NO 2 gas, and the highest response value is MoS 2 /rGO/GQDs-3, which is 15.2%.
  • the response of MoS 2 /rGO/GQDs-3 to different concentrations of NO 2 gas was tested, and the response value increased from 15.2% to 23.2% as the concentration of NO 2 gas increased from 5 ppm to 50 ppm.
  • the present invention uses FeCl3 as an oxidant to prepare a polypyrrole-modified MoS2/rGO/GQDs composite material by pyrrole in-situ gas-phase redox modification method, and tests the polypyrrole-modified MoS2/rGO/GQDs-3 composite sensor with different concentrations.
  • the test results show that when the NO2 gas concentration is 5 ppm, 10 ppm, 50 ppm, 100 ppm and 200 ppm, the response values are 25.3%, 28.3%, 30.9%, 33.1% and 38.5% respectively, and it is carried out rapidly in a short time Adsorption and desorption, compared with unmodified MoS2/rGO/GQDs sensor and MoS2/GQDs sensor, MoS2/rGO sensor response value is higher, showing excellent sensitivity, indicating polypyrrole conductive polymer and graphene sheet formation Synergistically improves the interaction between gas and ⁇ electrons, increases the electron transmission rate, makes electrons be extracted by NO2 gas faster, and the response value is improved.
  • Figure 5 is the repeatability response curve of the polypyrrole-modified MoS2/rGO/GQDs-3 composite gas sensor to 5 ppm NO2 gas. After three cycles of cyclic testing, the response The value remained at 25.3%, and the response time and recovery time remained stable without any attenuation, indicating that the polypyrrole-modified sensor had good response stability and repeatability.
  • the selectivity of the sensor is also very important.
  • the gas selectivity test of the polypyrrole-modified MoS 2 /rGO/GQDs composite gas sensor is represented by industrially produced organic gases, including acetone, formaldehyde, ethyl acetate, isopropyl Alcohol, n-hexane and chloroform were tested using the saturated solution vapor in the solvent bottle, and the results are shown in Figure 6 (50ppm).

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Abstract

一种聚合物修饰石墨烯复合材料及其传感器与应用，包括二硫化钼、石墨烯、石墨烯量子点以及聚合物。具体的，在二硫化钼、石墨烯、石墨烯量子点复合材料表面修饰聚合物，得到所述聚合物修饰石墨烯复合材料，解决了现有二硫化钼传感器需要加热才可检测二氧化氮的问题，在室温下可以检测二氧化氮，测试结果表明，该聚合物修饰石墨烯复合材料制备的气体传感器的响应值高，较未修饰传感器提高30％以上，而且具有优异的重复性和选择性。

Description

一种聚合物修饰石墨烯复合材料及其传感器与应用 技术领域
本发明属于气体传感器技术，具体涉及一种聚合物修饰石墨烯复合材料及其传感器与应用。
 背景技术
随着技术的发展，气体传感器在日常生活中的需求日益增大，而在其中NO 2气体的检测是气体环境污染的关键一项。目前被用作传感器的材料一般是纳米复合材料，其中石墨烯和MoS 2材料因其强吸附能力、大比表面积等优异的特性，使其在气体传感器领域的应用不断被开拓，基于纯石墨烯和MoS 2气敏传感研究，发现石墨烯的恢复时间较长，MoS 2需要高温，不能在室温下响应，将石墨烯和二硫化钼（MoS 2）两种材料复合，虽然有改善，但是响应性等依然偏低。
技术问题
本发明公开了一种聚合物修饰石墨烯复合材料，即在二硫化钼/石墨烯量子点/氧化石墨烯三元复合材料表面修饰聚吡咯。研究表明，本发明的复合材料具有更多活性位点，良好的热稳定性与化学稳定性，利于气体的吸附。对复合材料进行相应的形貌、晶相和组分的表征，研究结果表明，聚吡咯修饰处理的MoS 2/rGO/GQDs复合材料在响应灵敏度和检测极限方面相比MoS 2/rGO/GQDs复合材料、MoS 2/rGO和MoS 2/GQDs材料提升明显，而且具有优异的重复性和选择性。
技术解决方案
本发明公开了一种聚合物修饰石墨烯复合材料，包括二硫化钼、石墨烯、石墨烯量子点以及聚合物。优选的，本发明以二硫化钼、石墨烯、石墨烯量子点组成石墨烯复合材料，然后修饰聚合物，得到聚合物修饰石墨烯复合材料，具有更多活性位点，利于气体的吸附，更多的化学吸附氧参与反应，使得电子更快的被NO2气体抽取，使得聚吡咯修饰的MoS2/rGO/GQDs 复合材料在导电性提高的同时又可与气体分子充分接触反应，复合材料丰富的孔道为分子的吸附提供更多的反应位点，是提高材料气敏响应性能的有效手段。
本发明公开了上述聚合物修饰石墨烯复合材料在制备气体传感器中的应用，尤其在制备二氧化氮传感器中的应用。
本发明公开了一种气体传感器，包括基底与气敏材料，所述气敏材料为上述聚合物修饰石墨烯复合材料。其中的基底为现有产品，比如叉指电极，本发明的创造性在于在现有基底上复合新的气敏材料，获得新的传感器，具有优异的二氧化氮检测性能。
本发明公开了上述气体传感器的制备方法，将二硫化钼、氧化石墨烯、石墨烯量子点、水的混合物加热反应，得到石墨烯复合材料；再将石墨烯复合材料滴涂在基底表面，干燥后在石墨烯复合材料表面修饰聚合物，得到气体传感器。
本发明中，石墨烯为还原氧化石墨烯（rGO）；采用水热法制备得到石墨烯量子点（GQDs），采用水热法以钼酸钠和硫脲为钼源和硫源制备出花状的MoS 2，采用现有改进的Hummers法制备得到GO，以MoS 2、GO和GQDs为原料，采用水热法制备得到MoS 2/rGO/GQDs复合材料，再采用吡咯原位气相氧化还原修饰法制备得到聚吡咯修饰的MoS2/rGO/GQDs 复合材料，为本发明的产品。进一步制备为传感器，探究了室温下传感器对NO 2气体的响应特性。
本发明中，以苯并芘为原料，经过硝基化、冷冻、碱蚀、热反应，得到石墨烯量子点。
本发明中，以二水钼酸钠和硫脲为原料，经过水热反应，得到二硫化钼。优选的，水热反应的温度为160～220℃，时间为15～25小时。
本发明中，将二硫化钼、氧化石墨烯、石墨烯量子点、水的混合物加热反应，得到石墨烯复合材料；然后在石墨烯复合材料表面修饰聚合物，得到聚合物修饰石墨烯复合材料。具体的，加热反应后进行离心处理，取下层浓稠液体进行干燥，得到石墨烯复合材料。优选的，加热反应的温度为180～220℃，时间为10～15小时。优选的，二硫化钼、石墨烯量子点、氧化石墨烯的质量比（3～25）∶（0.8～1.2）∶1，优选为（5～15）∶1∶1。
本发明中，聚合物为聚吡咯；以吡咯为原料，在石墨烯复合材料表面进行气相聚合，得到聚合物修饰石墨烯复合材料。优选的，气相聚合以铁盐为氧化剂；气相聚合前，石墨烯复合材料进行表面处理，包括等离子处理、过硫酸铵水溶液浸泡、氢氧化钾水溶液浸泡。
 有益效果
本发明采用水热法制备得到GQDs的分散液，再采用简便的水热法制备得到和MoS 2/rGO/GQDs复合材料，通过滴涂MoS 2/rGO/GQDs复合材料分散液的方式转移到叉指电极上，制备得到复合材料传感器，再以吡咯为原料，在MoS 2/rGO/GQDs复合材料表面进行气相聚合，得到聚合物修饰石墨烯复合材料。测试结果表明，NO 2气体浓度为50 ppm 时，MoS 2/rGO/GQDs复合材料气体传感器具有23.2 %的响应值，本发明聚合物修饰石墨烯复合材料作为气敏材料的传感器达到30.9%，相比MoS 2/rGO、MoS 2/GQDs和MoS 2/rGO/GQDs都有明显提升，而且具有优异的重复性和选择性。
附图说明
图1 GQDs 的原子力表征图。
图2为SEM 图：（a）MoS 2/rGO/GQDs-1；（b）MoS 2/rGO/GQDs-2；（c）MoS 2/rGO/GQDs-3；（d）MoS 2/rGO/GQDs-4；（e）MoS 2/rGO/GQDs-5；（f）水热法制备的MoS 2。
图3为叉指电极的SEM 图。
图4为不同质量比的MoS 2/rGO/GQDs复合材料气体传感器对5 ppm NO 2的响应曲线。
图5为聚吡咯修饰MoS 2/rGO/GQDs-3复合材料气体传感器对5 ppm NO 2的重复性测试。
图6为聚吡咯修饰MoS 2/rGO/GQDs-3复合材料气体传感器的选择性测试。
本发明的实施方式
采用扫描电子显微镜（SEM)、X射线衍射仪（XRD）、傅里叶红外光谱（FT-IR）、拉曼光谱（Raman）、X 射线光电子能谱（XPS）分析其形貌、晶相和表面官能团，证明复合材料中各组分的成功制备及纯净程度。
实施例一 聚吡咯修饰石墨烯复合材料：石墨烯量子点（GQDs）制备，实验步骤如下：称取1 g的苯并芘于烧瓶中，加入80 ml的HNO 3溶液（质量浓度65%），将其置于80 ℃下反应12 h以完成硝基化反应，取出烧瓶自然却后使用去离子水对产物进行抽滤，直至滤液变为无色便得到产物1,3,6-三硝基芘；将上述产物1,3,6-三硝基芘于-52 ℃下冷冻干燥处理12 h，转变成泡沫状，然后称取1.5 g于300 ml浓度为2 mol/l的NaOH水溶液中，常规超声3 h然后磁力搅拌5 h，然后倒入反应釜，放置于烘箱中，200 ℃下反应8 h，冷却至室温后添加去离子水，利用0.22微米的微孔滤膜进行抽滤；将滤液进行透析处理两天，然后旋转蒸发处理，得到浓度1 mg/ml的GQDs溶液，留待进一步使用。对反应后的GQDs 颗粒进行AFM 形貌的测试，图1可以看出许多纳米点状的颗粒，半径在几十纳米不等，高度数纳米，类似于单层的盘状而非球状。
二硫化钼制备，流程如下：称取1.21 g的二水钼酸钠和2.36 g的硫脲于烧杯中，加水配置为40 ml的溶液，常规搅拌3 h后于200℃反应18 h；反应结束自然冷却至室温，用滴管吸出黄色的上清液，使用乙醇和去离子水洗涤底部沉淀，过滤后将滤饼转移至真空干燥箱中，60 ℃下干燥8 h得到MoS 2粉末。
采用改进的Hummers法制备得到氧化石墨烯，比如：室温下，向三口瓶中放入2 g 的天然石墨，然后加入50 ml 的浓硝酸（质量浓度65%），常规搅拌30 min，再加入1 g 的硝酸钠，冰浴下常规搅拌2 h。在半小时的时间内，3次放入累计7.3 g 的高锰酸钾，保持在35 ℃下搅拌2 h，溶液变为黄褐色。向溶液中加入80 ml 的去离子水，保持30 min，此过程中溶液温度会急剧上升。待溶液自然冷却至室温，加入30wt%的H 2O 2溶液，搅拌至溶液颜色变为亮黄色。将亮黄色的溶液用盐酸洗涤，进行反复透析，透析产物进行高速离心，向离心管的上清液中加入去离子水，利用细胞粉碎机进一步超声，得到均匀的GO分散液，浓度为1 mg/ml。
利用上述MoS 2粉末、GQDs溶液、GO分散液制备石墨烯复合材料，具体为：称取75 mg的二硫化钼粉末，加入到25 ml的去离子水中，常规搅拌后加入25 ml GO溶液（1mg/ml）和25 ml GQDs溶液（1mg/ml）（二硫化钼、石墨烯量子点、氧化石墨烯质量比为3∶1∶1），常规超声分散3 h随后搅拌5 h，得到混合液，将混合溶液转移至反应釜中，于200 ℃下反应12 h，反应结束自然冷却至室温，用吸管除掉上层的清液，添加去离子水，倒入离心管中，以10000 rpm/min的转速离心处理10 min，离心与稀释处理5次后，得到底部的浓稠液体，将其放置于冰箱中冷冻至冰块状，转移至冷冻干燥箱中处理16 h，得到泡沫状的MoS 2/rGO/GQDs复合材料，称为MoS 2/rGO/GQDs-1。
在上述制备方法基础上，更换GQDs溶液、GO分散液的体积，得到二硫化钼、石墨烯量子点、氧化石墨烯质量比为5∶1∶1、10∶1∶1、15∶1∶1、25∶1∶1，其余不变，得到的产品分别为MoS 2/rGO/GQDs-2、MoS 2/rGO/GQDs-3、MoS 2/rGO/GQDs-4、MoS 2/rGO/GQDs-5。
片状石墨烯为二硫化钼的生长提供位点并影响其团聚，从而对气敏材料的性能有影响，图2为MoS 2/rGO/GQDs复合材料以及二硫化钼的SEM图，可观察到许多褶皱状的石墨烯片堆叠在一块，MoS 2纳米花和GQDs的小颗粒分布在石墨烯片暴露的活性位点上，随着MoS 2反应加入量的逐渐增加，MoS 2/rGO/GQDs 复合材料中MoS 2的含量相应增大，产生团聚现象，不利于气体分子的吸附。
将MoS 2/rGO/GQDs复合材料先用氧等离子体常规处理10 min，然后置于1 mmol/L的APS（过硫酸铵）水溶液中浸泡2 h，烘箱中烘干，使其形成氨基的单分子层，再置于20 mmol/L的KOH水溶液中8 h，随后烘干，接着转移到20 mmol/L的FeCl3水溶液中12 h，再烘干，随后滴加0.1 ml的吡咯溶液于反应釜内胆底部，将MoS 2/rGO/GQDs复合材料转移至反应釜中，于90℃下反应12 h，以FeCl3为氧化剂引发吡咯的聚合，得到聚吡咯修饰的MoS2/rGO/GQDs。
对比例一：利用上述MoS 2粉末、GQDs溶液制备MoS 2/GQDs复合材料，具体为：称取75 mg的二硫化钼粉末，加入到25 ml的去离子水中，常规搅拌后加入GQDs溶液（二硫化钼、石墨烯量子点的质量比为10∶1），常规超声分散3 h随后搅拌5 h，得到混合液，将混合溶液转移至反应釜中，于90℃下反应12 h，反应结束自然冷却至室温，用吸管除掉上层的清液，添加去离子水，倒入离心管中，以10000 rpm/min的转速离心处理5min，离心与稀释处理5次后，得到底部的浓稠液体，将其放置于冰箱中冷冻至冰块状，转移至冷冻干燥箱中处理16 h，得到泡沫状的MoS 2/GQDs复合材料。
利用上述MoS 2粉末、GO分散液制备MoS 2/rGO复合材料，具体为：称取75 mg的二硫化钼粉末，加入到25 ml的去离子水中，常规搅拌后加入GO溶液（二硫化钼、氧化石墨烯质量比为10∶1），常规超声分散3 h随后搅拌5 h，得到混合液，将混合溶液转移至反应釜中，于200 ℃下反应12 h，反应结束自然冷却至室温，将黑色沉淀进行离心、去离子水和乙醇洗涤，于80℃下真空干燥，得到MoS 2/rGO复合材料。
将25 mL GO（1mg/ml）分散液常规超声分散3 h随后搅拌5 h，得到混合液，将混合溶液转移至反应釜中，于200℃下反应12 h，反应结束自然冷却至室温，将沉淀进行离心、去离子水和乙醇洗涤，于80℃下真空干燥，得到rGO。
现有叉指电极的SEM图见图3，将其贴在金属底座上并用线导通，然后将3μL气敏材料水分散液（浓度为1 mg/ml）滴涂在叉指电极上，自然晾干后真空干燥，得到传感器。气敏材料为MoS 2/rGO/GQDs复合材料、MoS 2/rGO复合材料、MoS 2/GQDs复合材料、MoS 2材料、rGO材料或者GQDs复合材料。
实施例二 传感器：采用与对比例一一样的叉指电极，将其贴在金属底座上并用线导通，然后将3μLMoS 2/rGO/GQDs复合材料水分散液（浓度为1 mg/ml）滴涂在叉指电极上，自然晾干后真空干燥，用氧等离子体常规处理MoS 2/rGO/GQDs复合材料10 min，然后置于1 mmol/L 的APS（过硫酸铵）水溶液中浸泡2 h，烘箱中烘干，使MoS 2/rGO/GQDs复合材料表面形成氨基的单分子层，再置于20 mmol/L的KOH水溶液中8 h，随后烘干，接着转移到20 mmol/L 的FeCl3水溶液中12 h，再烘干，随后滴加0.1 ml的吡咯溶液于反应釜内胆底部，将带有MoS 2/rGO/GQDs复合材料的叉指电极转移至反应釜中，于90 ℃下反应12 h，以FeCl3 为氧化剂引发吡咯的聚合，最后常规洗涤干燥，得到聚吡咯修饰的MoS2/rGO/GQDs，位于叉指电极表面，从而制备传感器。
对比例二：利用上述MoS 2粉末、GQDs溶液、GO分散液煅烧法制备石墨烯复合材料，具体为：称取75 mg的二硫化钼粉末与GO、GQDs混合（二硫化钼、石墨烯量子点、氧化石墨烯质量比为10∶1∶1，以浓缩液形式添加），常规研磨后置入管式炉，以5℃每分钟从室温升至350℃，保温1小时，自然冷却，得到R-MoS 2/rGO/GQDs复合材料，根据实施例二的方法，将MoS 2/rGO/GQDs复合材料替换为R-MoS 2/rGO/GQDs复合材料，得到对比传感器，对5 ppm NO 2气体的响应为3.5%（传感器制备以及测试方法与实施例一样）。
实施例三：在室温下进行NO 2气体的检测，测试时气敏元件处于密闭的空间，有效隔绝了外部的环境。以NO 2气体作检测气体，空气用来稀释NO 2得到不同浓度的待测气体。测试电压设置为5 mV，Agilent测试仪器收集的精准电流信息整合为I-V图，由此计算出气敏材料的电阻值。测试开始后，先通入100 s 时间的背景气体使输出的电流保持在稳定的范围，然后以一定比例通入背景气体和NO 2气体，安捷伦仪器会实时检测器件的电流数值，通过电流的变化推算出电阻的变化进而计算出传感器的响应值S（%），其计算公式如下： 
Figure 675514dest_path_image001
。
其中R 0为气敏材料在背景气下的初始电阻，R是气敏材料暴露于NO 2气体的实时电阻值。
图4为MoS 2/rGO/GQDs 复合材料对5 ppm NO 2气体的响应，响应值最高的是MoS 2/rGO/GQDs-3，为15.2 %。测试了MoS 2/rGO/GQDs-3对不同浓度NO 2气体的响应，随着NO 2气体的浓度从5 ppm增加至50 ppm，响应值从15.2 %增加到23.2 %。
本发明以FeCl3为氧化剂采用吡咯原位气相氧化还原修饰法制备得到聚吡咯修饰的MoS2/rGO/GQDs 复合材料，对聚吡咯修饰的  MoS2/rGO/GQDs-3复合材料传感器进行不同浓度的测试，测试结果为，NO2气体浓度为5 ppm、10 ppm、50 ppm、100 ppm 和200 ppm 时，响应值分别为25.3 %、28.3 %、30.9 %、33.1 %和38.5 %，在短时间内迅速地进行吸附与解吸附，相比未修饰处理的MoS2/rGO/GQDs 传感器和MoS2/GQDs 传感器、MoS2/rGO传感器响应值要高，显示出优异的灵敏度，说明聚吡咯导电高分子和石墨烯片层成协同提高了气体与π电子相互作用，提高了电子的传输速率，使得电子更快的被NO2 气体抽取，响应值有所提升。
测试聚吡咯修饰处理后MoS2-rGO-GQDs-3复合材料传感器对ppb 量级NO2 气体的响应，当NO2气体的浓度为50 ppb、100 ppb、200 ppb 和500 ppb时，响应值对应为14.2 %、15.6 %、17.9 %和18.8 %，具有良好的灵敏度，NO2 气体的浓度低至50 ppb浓度时仍具有14.2 %的响应，响应和恢复时间保持在150 s，说明经聚吡咯修饰后传感器不仅响应有所提升，检测范围也得到了有效的提升。
重复性对气体传感器具有十分重要的意义，图5是聚吡咯修饰的MoS2/rGO/GQDs-3复合材料气体传感器对5 ppm NO2 气体的重复性响应曲线，进行三个周期的循环测试后，响应值保持在25.3%，响应时间和恢复时间均保持稳定，未见丝毫的衰减，表明聚吡咯修饰的传感器具有完好的响应稳定性和重复性。
在室温下，测试了纯MoS 2纳米花、纯GQDs对NO 2气体的响应性能，结果表明不论对于多大浓度的NO 2气体，纯MoS 2或者纯GQDs都无响应，且纯GQDs的噪声非常大，性能很不稳定；rGO在室温下对5 ppm NO 2气体的响应为2.6%；三种单独材料在室温下气敏性能较差。MoS 2/rGO复合材料对50ppm NO 2气体的响应为17.3 %；MoS 2/GQDs复合材料对浓度50ppm NO 2气体的响应为13.5%，50ppb的响应值为9.1 %。
传感器的选择性也十分重要，对聚吡咯修饰的MoS 2/rGO/GQDs复合材料气体传感器进行气体的选择性测试，以工业生产的有机气体为代表，包括丙酮、甲醛、乙酸乙酯、异丙醇、正己烷和三氯甲烷，利用溶剂瓶中饱和的溶液蒸气进行测试，结果见图6（50ppm）。

Claims (10)

  1. 一种聚合物修饰石墨烯复合材料，其特征在于，包括二硫化钼、石墨烯、石墨烯量子点以及聚合物。
  2. 根据权利要求1所述聚合物修饰石墨烯复合材料，其特征在于，二硫化钼、石墨烯、石墨烯量子点的质量比（3～25）∶（0.8～1.2）∶1；聚合物为聚吡咯。
  3. 根据权利要求1所述聚合物修饰石墨烯复合材料，其特征在于，在二硫化钼、石墨烯、石墨烯量子点复合材料表面修饰聚合物，得到所述聚合物修饰石墨烯复合材料。
  4. 一种气体传感器，包括基底与气敏材料，其特征在于，所述气敏材料为权利要求1所述聚合物修饰石墨烯复合材料。
  5. 权利要求1所述聚合物修饰石墨烯复合材料或者权利要求4所述气体传感器在制备气体传感器中的应用。
  6. 根据权利要求5所述的应用，其特征在于，气体为二氧化氮。
  7. 权利要求1所述聚合物修饰石墨烯复合材料的制备方法，其特征在于，将二硫化钼、氧化石墨烯、石墨烯量子点、水的混合物加热反应，得到石墨烯复合材料；再采用吡咯为原料，在石墨烯复合材料表面进行气相聚合修饰聚合物，得到聚合物修饰石墨烯复合材料。
  8. 根据权利要求7所述聚合物修饰石墨烯复合材料的制备方法，其特征在于，加热反应的温度为180～220℃，时间为10～15小时；气相聚合以铁盐为氧化剂。
  9. 根据权利要求7所述聚合物修饰石墨烯复合材料的制备方法，其特征在于，采用水热法以苯化合物为原料制备得到石墨烯量子点；采用水热法以钼酸钠和硫脲为钼源和硫源制备出花状的二硫化钼。
  10. 权利要求4所述气体传感器的制备方法，其特征在于，将二硫化钼、氧化石墨烯、石墨烯量子点、水的混合物加热反应，得到石墨烯复合材料；将石墨烯复合材料滴涂在基底上，干燥，然后在石墨烯复合材料表面进行气相聚合修饰聚合物，得到气体传感器。
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CN104181209A (zh) * 2014-08-14 2014-12-03 电子科技大学 一种二氧化氮气体传感器及其制备方法
CN105845910A (zh) * 2016-05-01 2016-08-10 上海大学 花状MoS2@石墨烯纳米复合材料及其制备方法
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