阅读说明：本技术 一种器件表面原位组装石墨烯气凝胶的制备方法及气敏应用 (Preparation method and gas-sensitive application of graphene aerogel assembled on surface of device in situ ) 是由 邵高峰 沈晓冬 于 2019-10-22 设计创作，主要内容包括：本发明涉及一种器件表面原位组装石墨烯气凝胶的制备方法及气敏应用,本发明将石墨烯气凝胶的制备过程和转移到器件表面过程合二为一,极大地简化了石墨烯气凝胶气体传感器的制备过程,最大限度地提高了石墨烯气凝胶的气体传感性能。原位组装得到的聚吡咯耦合W<Sub>18</Sub>O<Sub>49</Sub>纳米线/氮掺杂石墨烯气凝胶的气体传感器对低浓度NO<Sub>2</Sub>具有优异的响应性能。此外该方法可适用于制备导电聚合物-纳米金属氧化物-石墨烯三元复合气凝胶,以及在其他功能器件表面组装石墨烯基气凝胶。(The invention relates to a preparation method and gas-sensitive application of graphene aerogel assembled on the surface of a device in situ. Polypyrrole coupling W obtained by in-situ assembly 18 O 49 Nanowire/nitrogen-doped graphene aerogel gas sensor for low-concentration NO 2 Has excellent response performance. In addition, the method can be suitable for preparing the conductive polymer-nano metal oxide-graphene ternary composite aerogel and assembling the graphene-based aerogel on the surfaces of other functional devices.)

1. A preparation method of graphene aerogel assembled on the surface of a device in situ is characterized by comprising the following steps: the method comprises the following steps:

1)W₁₈O₄₉preparing the nano wire: weighing WCl₆Dissolving the powder in absolute ethyl alcohol, fully stirring for 10-30min to form a light yellow solution, adding polyvinylpyrrolidone (PVP), and fully stirring for 10-30 min;

then transferring the prepared solution into a reaction kettle for solvothermal reaction, wherein the reaction temperature is 160-200 ℃, and the reaction time is 12-48 h; reacting the resultant W₁₈O₄₉Repeatedly washing the nanowires by absolute ethyl alcohol and deionized water for later use;

2) hydroxylating the surface of the device: preparing Piranha solution, placing the device in Piranha solution, treating at 90 ℃ for 30 minutes, then thoroughly rinsing with ultrapure water and drying with flowing nitrogen to obtain a clean surface;

3) preparation of polypyrrole coupled W₁₈O₄₉Nanowire/graphene hydrogel PrGOWH: mixing W in the step 1)₁₈O₄₉Mixing the nanowires and the graphene oxide aqueous solution according to a certain mass ratio, carrying out ultrasonic dispersion for 15-60 min, then adding a pyrrole monomer, and carrying out ultrasonic dispersion for 15-60 min;

and then, dropwise transferring the mixed solution to the surface of the hydroxylated device in the step 2) for in-situ assembly, wherein the reaction temperature is 20-40 ℃, the reaction time is 12-36 h, and polypyrrole coupling W is obtained on the surface of the device₁₈O₄₉Nanowire/graphene hydrogel PrGOWH;

4) polypyrrole coupling W for in-situ assembly on device surface₁₈O₄₉Nanowire/graphene aerogel: coupling the polypyrrole in the step 3) with W₁₈O₄₉Putting the nanowire/graphene hydrogel PrGOWH device into an aging solution, aging for 24-72 h, freezing for 12-24 h at-20 to-80 ℃, taking out, putting into a freeze drying device, and drying for 12-72 h to obtain polypyrrole coupling W₁₈O₄₉Nanowire/graphene aerogel PrGOWA;

5) preparation of polypyrrole coupled W₁₈O₄₉Nanowire/nitrogen-doped graphene aerogel PGWA: subjecting the product obtained in step 4) toCoupled with polypyrrole W₁₈O₄₉Placing the nanowire/graphene aerogel PrGOWA in a tube furnace, heating to 200-300 ℃ at a heating rate of 1-5 ℃/min under the protection of atmosphere, keeping the temperature for 1-3 h, and then naturally cooling to obtain polypyrrole coupling W₁₈O₄₉Nanowire/nitrogen doped graphene aerogel PGWA.

2. The method for preparing the graphene aerogel on the surface of the device in situ according to claim 1, wherein the method comprises the following steps: in step 1), WCl₆The mass/volume ratio of the powder to the absolute ethyl alcohol is (5-20): (5-7) g/L; WCl₆The mass ratio of the powder to the polyvinylpyrrolidone PVP is (50-200): (0.1-0.3).

3. The method for preparing the graphene aerogel on the surface of the device in situ according to claim 1, wherein the method comprises the following steps: in the step 2), the Piranha solution is prepared by weighing 98% H₂SO₄And H₂O₂The solution with the volume ratio of 7:3 is mixed evenly.

4. The method for preparing the graphene aerogel on the surface of the device in situ according to claim 1, wherein the method comprises the following steps: the device in the step 2) is made of Al₂O₃The Pt-based heating device comprises an insulating substrate, a Pt conductive electrode and a Pt heating electrode, wherein the conductive electrode and the heating electrode are respectively positioned on two sides of the insulating substrate.

5. The method for preparing the graphene aerogel on the surface of the device in situ according to claim 1, wherein the method comprises the following steps: the concentration of the graphene oxide aqueous solution in the step 3) is 2-10 mg/ml; w₁₈O₄₉The mass ratio of the nanowire to the graphene oxide is (1:10) - (10:1), and the mass ratio of the graphene oxide to the pyrrole monomer is (10:1) - (1: 10).

6. The method for preparing the graphene aerogel on the surface of the device in situ according to claim 1, wherein the method comprises the following steps: the aging solution in the step 4) is an organic solvent/deionized water mixed solution, and the volume ratio of the organic solvent/deionized water is (1:10) - (1: 5); wherein the organic solvent is one of ethanol, acetone or isopropanol.

7. The method for preparing the graphene aerogel on the surface of the device in situ according to claim 1, wherein the method comprises the following steps: the protective atmosphere in the step 5) is one of nitrogen, argon or argon/hydrogen mixed gas.

8. Gas sensitive application of the in situ assembled graphene aerogel on the device surface of claim 1.

Technical Field

The invention relates to the technical field of graphene aerogel preparation and gas sensors, in particular to a preparation method and gas-sensitive application of graphene aerogel assembled on the surface of a device in situ.

Background

Graphene is unique among a plurality of gas sensitive materials due to the characteristics of high conductivity, high electron transfer rate, high specific surface area and the like. However, the intrinsic graphene gas-sensitive material has the disadvantages of low sensitivity, slow response, low selectivity, non-reversibility and the like at room temperature, so the performance of the graphene-based gas-sensitive material is improved by introducing defects, element doping, metal/metal oxide/polymer functionalization, construction of a three-dimensional graphene structure, and the like by using a micro-heater.

Researches show that the self-assembly of the two-dimensional graphene oxide nanosheets into the three-dimensional graphene wet gel/aerogel material is proved to be an effective means for improving the gas-sensitive performance of graphene due to the high specific surface area and the hierarchical pore structure, such as chemically functionalized graphene hydrogel/aerogel, metal oxide/sulfide modified graphene aerogel and the like.

However, the fabrication of the current three-dimensional graphene aerogel based sensor is realized in two steps (CN108680605A, CN110161080A, Advanced Functional Materials,26(2016) 5158-. The method has the defects of uncontrollable appearance, reduced specific surface area, poor contact between the gas-sensitive material and an electrode and the like, and the performance of the device is seriously influenced.

Disclosure of Invention

The patent provides a method of device surface normal position equipment graphite alkene aerogel, unites two into one the preparation process of graphite alkene aerogel and the process of transferring to the device surface, has greatly simplified graphite alkene aerogel gas sensor's preparation process, furthest has improved the sensing performance of graphite alkene aerogel.

In order to achieve the purpose, the technical scheme provided by the invention is as follows:

a preparation method of graphene aerogel assembled on the surface of a device in situ comprises the following steps:

1)W₁₈O₄₉preparing the nano wire: weighing WCl₆Dissolving the powder in absolute ethyl alcohol, fully stirring for 10-30min to form a light yellow solution, adding polyvinylpyrrolidone (PVP), and fully stirring for 10-30 min;

then transferring the prepared solution into a reaction kettle for solvothermal reaction, wherein the reaction temperature is 160-200 ℃, and the reaction time is 12-48 h; reacting the resultant W₁₈O₄₉Repeatedly washing the nanowires by absolute ethyl alcohol and deionized water for later use;

2) hydroxylating the surface of the device: preparing Piranha solution, placing the device in Piranha solution, treating at 90 ℃ for 30 minutes, then thoroughly rinsing with ultrapure water and drying with flowing nitrogen to obtain a clean surface;

3) preparation of polypyrrole coupled W₁₈O₄₉Nanowire/graphene hydrogel PrGOWH: mixing W in the step 1)₁₈O₄₉Mixing the nanowires and the graphene oxide aqueous solution according to a certain mass ratio, carrying out ultrasonic dispersion for 15-60 min, then adding a pyrrole monomer, and carrying out ultrasonic dispersion for 15-60 min;

and then, dropwise transferring the mixed solution to the surface of the hydroxylated device in the step 2) for in-situ assembly, wherein the reaction temperature is 20-40 ℃, the reaction time is 12-36 h, and polypyrrole coupling W is obtained on the surface of the device₁₈O₄₉Nanowire/graphene hydrogel PrGOWH;

4) polypyrrole coupling W for in-situ assembly on device surface₁₈O₄₉Nanowire/graphene aerogel: coupling the polypyrrole in the step 3) with W₁₈O₄₉Putting the nanowire/graphene hydrogel PrGOWH device into an aging solution, aging for 24-72 h, freezing for 12-24 h at-20 to-80 ℃, taking out, putting into a freeze drying device, and drying for 12-72 h to obtain polypyrrole coupling W₁₈O₄₉Nanowire/graphene aerogel PrGOWA;

5) preparation of polypyrrole coupled W₁₈O₄₉Nanowire/nitrogen-doped graphene aerogel PGWA: coupling the polypyrrole obtained in the step 4) with W₁₈O₄₉Placing the nanowire/graphene aerogel PrGOWA in a tube furnace, heating to 200-300 ℃ at a heating rate of 1-5 ℃/min under the protection of atmosphere, keeping the temperature for 1-3 h, and then naturally cooling to obtain polypyrrole coupling W₁₈O₄₉Nanowire/nitrogen doped graphene aerogel PGWA.

In step 1), WCl₆The mass/volume ratio of the powder to the absolute ethyl alcohol is (5-20): (5-7) g/L; WCl₆The mass ratio of the powder to the polyvinylpyrrolidone PVP is (50-200): (0.1-0.3).

In the step 2), the Piranha solution is prepared by weighing 98% H₂SO₄And H₂O₂The solution with the volume ratio of 7:3 is mixed evenly.

The device in the step 2) is made of Al₂O₃An insulating substrate, a Pt conductive electrode and a Pt heating electrode, wherein the conductive electrode and the heating electrode are respectively positioned on the insulationOn both sides of the substrate.

The concentration of the graphene oxide aqueous solution in the step 3) is 2-10 mg/ml; w₁₈O₄₉The mass ratio of the nanowires to the graphene oxide is (1:10) - (10: 1); the mass ratio of the graphene oxide to the pyrrole monomer is (10:1) - (1: 10).

The aging solution in the step 4) is an organic solvent/deionized water mixed solution, and the volume ratio of the organic solvent/deionized water is (1:10) - (1: 5); wherein the organic solvent is one of ethanol, acetone or isopropanol.

The protective atmosphere in the step 5) is one of nitrogen, argon or argon/hydrogen mixed gas.

The invention also protects the gas-sensitive application of the prepared graphene aerogel assembled on the surface of the device in situ.

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

according to the invention, the preparation process of the graphene aerogel and the process of transferring the graphene aerogel to the surface of a device are combined into a whole, so that the preparation process of the graphene aerogel gas sensor is greatly simplified, and the gas sensing performance of the graphene aerogel is improved to the maximum extent. Polypyrrole coupling W obtained by in-situ assembly₁₈O₄₉Nanowire/nitrogen-doped graphene aerogel gas sensor for low-concentration NO₂Has excellent response performance. In addition, the method can be suitable for preparing the conductive polymer-nano metal oxide-graphene ternary composite aerogel and assembling the graphene-based aerogel on the surfaces of other functional devices.

The method overcomes the problems of uncontrollable appearance, reduced specific surface area, poor contact between the gas-sensitive material and an electrode and the like caused by the separation of the preparation process of the gas-sensitive material and the transfer of the gas-sensitive material to the surface of a device, and adopts an in-situ assembly strategy to prepare polypyrrole coupled W₁₈O₄₉The nanowire/nitrogen-doped graphene aerogel gas sensor greatly simplifies the preparation process, avoids the agglomeration of gas-sensitive materials, enhances the contact between the gas-sensitive materials and electrodes, and improves the sensing performance to the maximum extent.

Drawings

Fig. 1 is a flow chart of in-situ assembly of graphene aerogel on the surface of the device in example 1.

FIG. 2 shows scanning electron microscope pictures (a-d) and transmission electron microscope pictures (e) at different magnifications of PGWA on the surface of the device obtained in example 1

FIG. 3 shows the graphene aerogels (a) prepared in examples 1 and 2 for different concentrations of NO₂(ii) a response curve of (b) a cyclic response curve at a concentration of 975 ppb.

FIG. 4 is a comparison of the response performance of graphene gas sensors reported in the present patent and literature.

Detailed Description

The present invention will be further described with reference to the following specific examples.