A method for preparing porous graphene materials for carbon dioxide sensing, its products and applications

Abstract

This invention relates to a method for preparing porous graphene materials for carbon dioxide sensing, as well as its products and applications, belonging to the field of graphene material preparation technology. The invention mainly involves placing a ring-shaped catalytic metal foil at the front end of a silicon substrate in a tube furnace, then introducing gaseous carbon source, argon, hydrogen, and argon gas after passing through an organic solution with a pH greater than 7 through different inlets. The temperature is raised to 800–1080°C and held for 0.5–600 min, thus growing porous graphene in the tube furnace. The preparation method of this invention employs a remote catalytic approach (placing the ring-shaped catalytic metal foil at the front end of the silicon substrate instead of direct mixing), which lowers the graphene preparation temperature and improves the preparation efficiency. Furthermore, the introduction of additional argon gas carrying potassium hydroxide solution into the tube furnace allows the potassium hydroxide solution to effectively control the formation of the porous graphene film.

Description

Technical Field

[0001] This invention belongs to the field of graphene material preparation technology, and relates to a method for preparing porous graphene materials for carbon dioxide sensing, as well as its products and applications. Background Technology

[0002] With increasing environmental awareness, carbon dioxide monitoring and emission reduction have become increasingly important. Traditional carbon dioxide sensors are mainly based on optical or electrochemical methods. While these methods are effective, they are typically complex, costly, and require frequent maintenance. Therefore, developing novel, efficient, and low-cost carbon dioxide sensors has become a current research hotspot.

[0003] Graphene is a two-dimensional material composed of carbon atoms, possessing excellent electrical, thermal, and mechanical properties, and has broad application prospects in the field of sensors. However, traditional preparation methods, such as mechanical exfoliation and redox methods, are insufficient to obtain graphene films with large specific surface areas.

[0004] Therefore, developing an efficient and controllable method for preparing porous graphene films to obtain graphene films with large specific surface areas is of great significance for the practical application of graphene in carbon dioxide sensors. Summary of the Invention

[0005] In view of this, one objective of the present invention is to provide a method for preparing a porous graphene material for carbon dioxide sensing; a second objective of the present invention is to provide a porous graphene material for carbon dioxide sensing; and a third objective of the present invention is to provide an application of the porous graphene material for carbon dioxide sensing in the preparation of carbon dioxide sensors.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] 1. A method for preparing a porous graphene material for carbon dioxide sensing, the method comprising the following steps:

[0008] (1) Place the silicon substrate in the middle of the tubular furnace with a four-way valve connected at the inlet, and place an annular catalytic metal foil between the silicon substrate and the inlet of the tubular furnace.

[0009] (2) Carrier gas and hydrogen are introduced into the tubular furnace through the first inlet of the four-way valve;

[0010] (3) At the same time, another carrier gas is passed through an organic solution with pH > 7 and then introduced into the tubular furnace through the second inlet of the four-way valve;

[0011] (4) Raise the furnace temperature of the tube furnace to 800-1080℃, and then introduce a gaseous carbon source through the third inlet of the tube furnace and maintain it for 0.5-600 min to grow porous graphene in the tube furnace.

[0012] The carrier gas is an inert gas.

[0013] Preferably, in step (1), the annular catalytic metal foil comprises copper or nickel;

[0014] The mass ratio of the silicon substrate to the annular catalytic metal foil is 100:0.1 to 200.

[0015] Preferably, in step (2), the gaseous carbon source includes any one or more of methane, ethylene, or acetylene.

[0016] Preferably, in step (3), the solvent in the organic solution with pH > 7 is any one of methanol, ethanol or formaldehyde;

[0017] The organic solution with pH > 7 contains hydroxide ions or hydroxyl groups.

[0018] More preferably, the concentration of hydroxide ions or hydroxyl groups in the organic solution with pH > 7 is 0.001 to 1 mol / L.

[0019] Preferably, the flow rates of the carrier gas and hydrogen in step (2), the carrier gas in step (3), and the gaseous carbon source in step (4) are 300:30-50:100:4-5.

[0020] Preferably, the mass flow rate ratio of the silicon substrate in step (1) to the gaseous carbon source in step (4) is 5000:4~5, mg:sccm.

[0021] 2. Porous graphene material prepared according to the above preparation method.

[0022] 3. Application of the above-mentioned porous graphene materials in the preparation of carbon dioxide sensors.

[0023] The beneficial effects of this invention are as follows: This invention discloses a method for preparing porous graphene materials for carbon dioxide sensing. The method mainly involves placing a ring-shaped catalytic metal foil at the front end of a silicon substrate in a tube furnace, then introducing a gaseous carbon source, a carrier gas (nitrogen or argon), hydrogen, and argon gas after passing through an organic solution with pH > 7 through different inlets. The temperature is raised to 800–1080°C and held for 0.5–600 min, thereby growing porous graphene in the tube furnace. This invention employs a remote catalytic method (placing the ring-shaped catalytic metal foil at the front end of the silicon substrate instead of direct mixing), which lowers the graphene preparation temperature and improves the preparation efficiency. Furthermore, introducing additional argon gas carrying potassium hydroxide solution into the tube furnace allows the potassium hydroxide solution to effectively control the formation of the porous graphene film. This invention's preparation method is suitable for large-scale production of porous graphene films, offering advantages of high efficiency and low cost. Simultaneously, the porous graphene material prepared by this invention exhibits excellent electrical, thermal, and mechanical properties, showing promising application prospects in the fabrication of carbon dioxide sensors.

[0024] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0025] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0026] Figure 1 This is a diagram showing the gas path structure during the preparation of the porous graphene material for carbon dioxide sensing according to the present invention.

[0027] Figure 2 This diagram shows the positional relationship between the silicon substrate and the annular catalytic metal foil in a tube furnace.

[0028] Figure 3 A photograph of a four-way valve connected to the inlet of a tubular furnace;

[0029] Figure 4 The image shows the morphology of the porous graphene material prepared in Example 1.

[0030] Figure 5 Raman spectroscopy was performed on the porous graphene material prepared in Example 1.

[0031] Figure 6 The image shows the morphology of the porous graphene material prepared in Example 2.

[0032] Figure 7Raman spectroscopy was performed on the porous graphene material prepared in Example 2. Detailed Implementation

[0033] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0034] The gas path structure in the preparation process of porous graphene materials for carbon dioxide sensing in Example 1 or Example 2 is as follows: Figure 1 As shown.

[0035] Example 1

[0036] A method for preparing porous graphene materials for carbon dioxide sensing is shown below:

[0037] (1) Place the silicon substrate in the middle of the tube furnace, and place an annular copper ring as an annular catalytic metal foil (e.g., ...) between the silicon substrate and the entrance of the tube furnace. Figure 2 As shown), then connect a four-way valve (as shown in the image) at the inlet of the tubular furnace. Figure 3 As shown in the figure, the mass ratio of silicon substrate to annular catalytic metal foil is 100:0.1;

[0038] (2) Carrier gas (argon) and hydrogen are introduced into the tubular furnace through the first inlet of the four-way valve, wherein the flow rates of argon and hydrogen are 300 sccm and 50 sccm, respectively.

[0039] (3) At the same time, another carrier gas (argon) is passed through a methanol solution containing potassium hydroxide (the concentration of potassium hydroxide in the organic solution containing potassium hydroxide is 0.05 mol / L) and then introduced into the tube furnace through the second inlet of the four-way valve at a flow rate of 100 sccm.

[0040] (4) Raise the furnace temperature of the tube furnace to 1050°C, and then introduce gaseous carbon source (methane) into the third inlet of the tube furnace at a flow rate of 5 sccm (wherein the mass flow rate ratio of the silicon substrate in step (1) to the gaseous carbon source in step (4) is 5000:5, mg:sccm), and keep it for 120 min to grow porous graphene in the tube furnace.

[0041] Figure 4This is a morphology image of the porous graphene material prepared in Example 1. From... Figure 4 As can be seen from the example, the preparation method in Example 1 can indeed obtain uniform porous graphene materials.

[0042] Figure 5 Raman spectroscopy was performed on the porous graphene material prepared in Example 1. Figure 5 The characteristic peaks of the Raman test results further indicate that the product obtained by the preparation method in Example 1 is indeed a porous graphene material.

[0043] The porous graphene material prepared by the method in Example 1 was then subjected to hydroxylation treatment, specifically as follows: 98% concentrated sulfuric acid and 30% hydrogen peroxide were mixed in an ice-water bath, stirred until homogeneous, and then cooled to room temperature to obtain a reaction solution. The porous graphene material prepared by the method in Example 1 was immersed in the reaction solution for hydroxylation treatment to obtain a hydroxylated porous graphene film, which was then formed into a 1*1 mm film. 2 The gas-sensitive device showed that the response of the prepared porous graphene film to 500 ppm carbon dioxide was 0.87%.

[0044] Example 2

[0045] A method for preparing porous graphene materials for carbon dioxide sensing is shown below:

[0046] (1) Place the silicon substrate in the middle of the tube furnace, place a nickel ring as an annular catalytic metal foil between the silicon substrate and the inlet of the tube furnace, and connect a four-way valve at the inlet of the tube furnace, wherein the mass ratio of the silicon substrate to the annular catalytic metal foil is 100:200.

[0047] (2) Nitrogen and hydrogen are introduced into the first inlet of the tubular furnace, with flow rates of 300 sccm and 30 sccm for nitrogen and hydrogen, respectively.

[0048] (3) At the same time, argon gas is passed through an ethanol solution containing potassium hydroxide (the concentration of potassium hydroxide in the organic solvent containing potassium hydroxide is 1.0 mol / L) and then introduced into the tube furnace through the second inlet of the four-way valve at a flow rate of 100 sccm.

[0049] (4) Raise the furnace temperature of the tube furnace to 1080°C, and then introduce gaseous carbon source (ethylene) into the third inlet of the tube furnace at a flow rate of 4 sccm (wherein the mass flow rate ratio of the silicon substrate in step (1) to the gaseous carbon source in step (4) is 5000:4, mg:sccm), and keep it for 600 min, so that porous graphene can be grown in the tube furnace.

[0050] Figure 6This is a morphology image of the porous graphene material prepared in Example 2. From... Figure 6 As can be seen from the example, the preparation method in Example 2 can indeed obtain uniform porous graphene materials.

[0051] Figure 7 Raman spectroscopy was performed on the porous graphene material prepared in Example 2. Figure 7 The characteristic peaks of the Raman test results further indicate that the product obtained by the preparation method in Example 2 is indeed a porous graphene material.

[0052] The porous graphene material prepared by the method in Example 2 was then subjected to hydroxylation treatment. The specific method is as follows: 98% concentrated sulfuric acid and 30% hydrogen peroxide were mixed in an ice-water bath, stirred evenly, and then cooled to room temperature to obtain a reaction solution. The porous graphene material prepared by the method in Example 2 was immersed in the reaction solution for hydroxylation treatment to obtain a hydroxylated porous graphene film, which was then formed into a 1*1mm film. 2 The gas-sensitive device showed that the response of the prepared porous graphene film to 500 ppm carbon dioxide was 1.31%.

[0053] In summary, this invention discloses a method for preparing porous graphene materials for carbon dioxide sensing. The method primarily involves placing a ring-shaped catalytic metal foil at the front end of a silicon substrate in a tube furnace, then introducing a gaseous carbon source, a carrier gas (nitrogen or argon), hydrogen, and argon gas passed through an organic solution with a pH > 7 through different inlets. The temperature is raised to 800–1080°C and held for 0.5–600 min, allowing porous graphene to grow in the tube furnace. This method employs a remote catalytic approach (placing the ring-shaped catalytic metal foil at the front end of the silicon substrate instead of direct mixing), reducing the graphene preparation temperature and improving efficiency. Furthermore, introducing additional argon gas carrying potassium hydroxide solution into the tube furnace allows the potassium hydroxide solution to effectively control the formation of the porous graphene film. This method is suitable for large-scale production of porous graphene films, offering advantages of high efficiency and low cost. Simultaneously, the porous graphene material prepared by this invention exhibits excellent electrical, thermal, and mechanical properties, showing promising application prospects in the fabrication of carbon dioxide sensors.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing porous graphene material for carbon dioxide sensing, characterized in that, The preparation method includes the following steps: (1) Place the silicon substrate in the middle of the tubular furnace with a four-way valve connected at the inlet, and place an annular catalytic metal foil between the silicon substrate and the inlet of the tubular furnace; (2) Carrier gas and hydrogen are introduced into the tubular furnace through the first inlet of the four-way valve; (3) At the same time, another carrier gas is passed through an organic solution with pH > 7 and then introduced into the tubular furnace through the second inlet of the four-way valve; The solvent in the organic solution with pH > 7 is either methanol or ethanol. The organic solution with pH > 7 contains potassium hydroxide; (4) Raise the furnace temperature of the tube furnace to 800~1080℃, and then introduce gaseous carbon source from the third inlet of the tube furnace and maintain it for 0.5~600min to grow porous graphene in the tube furnace. The carrier gas is an inert gas.

2. The preparation method according to claim 1, characterized in that, In step (1), the annular catalytic metal foil includes copper or nickel; The mass ratio of the silicon substrate to the annular catalytic metal foil is 100:0.1~200.

3. The preparation method according to claim 1, characterized in that, In step (4), the gaseous carbon source includes any one or more of methane, ethylene, or acetylene.

4. The preparation method according to claim 1, characterized in that, In step (3), the concentration of potassium hydroxide in the organic solution with pH > 7 is 0.001~1 mol / L.

5. The preparation method according to claim 1, characterized in that, The flow rates of the carrier gas and hydrogen in step (2), the carrier gas in step (3), and the gaseous carbon source in step (4) are 300:30~50:100:4~5.

6. The preparation method according to claim 1, characterized in that, The mass flow rate ratio of the silicon substrate in step (1) to the gaseous carbon source in step (4) is 5000:4~5, mg:sccm.

7. The porous graphene material prepared by the preparation method according to any one of claims 1 to 6.

8. The application of the porous graphene material of claim 7 in the preparation of carbon dioxide sensors.

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