Preparation method of silylene / graphene composite material

Abstract

The invention relates to the technical field of material preparation, in particular to a preparation method of a silylene / graphene composite material, which comprises the following steps: adding calcium silicide into acetonitrile, stirring to uniformly disperse the calcium silicide into an acetonitrile solution, then adding the acetonitrile solution of transition metal inorganic salt into the acetonitrile solution while continuously stirring, and uniformly stirring to obtain the silylene / graphene composite material. Stirring for one to two weeks, filtering, collecting a sample, washing with acetonitrile for multiple times, and fully drying the obtained product to obtain silylene; and putting the prepared silylene into a tubular furnace, heating the silylene to 500 DEG C at a rate of 5 DEG C / min in a mixed atmosphere of acetylene and argon, keeping the temperature for 2 hours, and naturally cooling to obtain the silylene / graphene composite material. Calcium silicide is topologically converted into silylene through an in-situ replacement reaction by utilizing the weak oxidizing property of transition metal ions, acetylene is further converted into graphene under the heating condition by taking a metal simple substance generated in the replacement reaction as a catalyst, and the preparation process of the silylene / graphene composite material is simplified.

Description

Technical Field

[0001] The invention relates to the technical field of material preparation, and in particular to a method for preparing a silicene / graphene composite material. Background Art

[0002] Because of the ultra-high theoretical specific capacity (4200 mA hg -1 ) and a lower lithium insertion voltage (0.2 − 0.3 V vs .Li / Li + ), silicon is a very promising negative electrode material for lithium-ion batteries. However, due to the huge volume change during the lithium stripping / insertion process and the poor electronic conductivity, the cycle life of silicon negative electrodes is short and the rate performance is poor, which seriously hinders the practical application of silicon negative electrodes. The structure of two-dimensional silicene is similar to that of graphene, with a honeycomb lattice structure and weak interlayer van der Waals forces. The large interlayer space allows silicene to have enough space to adsorb and migrate lithium ions, effectively preventing the breakage of covalent bonds and structural collapse of silicon during the lithium stripping / insertion process, thereby improving the cycle stability of silicon negative electrodes. For example, silicene prepared by epitaxial growth exhibits excellent cycle stability and rate performance when used as a negative electrode material for lithium-ion batteries. At present, there are few studies on the composite of silicene and graphene materials.

[0003] Chinese patent publication number CN118908149A discloses a method for preparing and applying 3D printed silicene-based composite structural materials, which uses a topological chemical method to prepare silicene nanosheets, uses an improved Hummers method to prepare graphene oxide, and then adds the two to a cellulose nanofiber aqueous solution in sequence, and each addition requires ultrasonic dispersion to obtain a high-concentration fluid. Its preparation process is complicated. Summary of the invention

[0004] The present invention solves the problems in the related art and proposes a method for preparing a silicene / graphene composite material. Calcium silicide is used as a raw material, and the weak oxidizing property of transition metal ions is utilized to topologically convert the calcium silicide into silicene through an in-situ replacement reaction. The metal element produced in the replacement reaction is further used as a catalyst to convert acetylene into graphene under heating conditions. Since the metal element is distributed between the layers of silicene, the catalytically generated graphene is also distributed between the layers of silicene to form a silicene / graphene composite structure. The present invention gives full play to the structural characteristics of calcium silicide, cleverly utilizes the metal element generated in-situ, and simplifies the preparation process of the silicene / graphene composite material.

[0005] In order to solve the above technical problems, the present invention is achieved through the following technical solutions: a method for preparing a silicene / graphene composite material, the steps are as follows: S1. Preparation of silicene: Calcium silicide is added to acetonitrile, and stirred thoroughly to make the calcium silicide evenly dispersed in the acetonitrile solution. Then, an acetonitrile solution of a transition metal inorganic salt is added thereto under continuous stirring. After stirring for one to two weeks, the sample is collected by filtration and washed with acetonitrile several times. The obtained product is silicene after being fully dried. S2. Preparation of silicene / graphene composite material: Place the prepared silicene in a tubular furnace, and in a mixed atmosphere of acetylene and argon, heat the silicene to 500°C at a rate of 5°C / min, and maintain at this temperature for 2h. After natural cooling, the silicene / graphene composite material can be obtained.

[0006] As a preferred embodiment, in step S1, the transition metal inorganic salt is nickel nitrate.

[0007] As a preferred embodiment, the concentration of the nickel nitrate acetonitrile solution is 0.2-0.5 mol / L.

[0008] As a preferred embodiment, the concentration of the calcium silicide acetonitrile solution is 0.05-0.1 mol / L.

[0009] As a preferred embodiment, in step S1, the product is dried at a temperature of 50-70°C.

[0010] As a preferred embodiment, in step S2, the volume ratio of acetylene to argon is 1:(18-20).

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention uses calcium silicide as a raw material, utilizes the weak oxidizing property of transition metal ions, topologically converts calcium silicide into silicene through an in-situ replacement reaction, further uses a metal element produced in the replacement reaction as a catalyst, and converts acetylene into graphene under heating conditions; since the metal element is distributed between the layers of silicene, the catalytically generated graphene is also distributed between the layers of silicene, forming a silicene / graphene composite structure; the present invention gives full play to the structural characteristics of calcium silicide, cleverly utilizes the in-situ generated metal element, and simplifies the preparation process of the silicene / graphene composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a scanning electron microscope image of the silicene / graphene composite material of the present invention; Figure 2 It is the X-ray diffraction pattern of the silicene / graphene composite material of the present invention. DETAILED DESCRIPTION

[0013] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0014] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0015] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0016] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0017] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0018] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0019] Example 1

[0020] Solution configuration: 0.075 mol / L calcium silicide acetonitrile solution (40 mL): Take 0.288 g of calcium silicide and add it to 40 mL of acetonitrile. Stir thoroughly to make the calcium silicide evenly dispersed in the acetonitrile solution.

[0021] 0.3 mol / L nickel nitrate acetonitrile solution (40 mL): Take 2.192 g of nickel nitrate into 40 mL of acetonitrile and stir thoroughly to make the nickel nitrate evenly dispersed in the acetonitrile solution. A method for preparing a silicene / graphene composite material, the specific steps are as follows: (1) Synthesis of silicene First, add 40 mL of 0.3 mol / L nickel nitrate solution in acetonitrile to 40 mL of 0.075 mol / L calcium silicide solution in acetonitrile under constant stirring. Stir for two weeks, then filter and rinse with acetonitrile 4 to 5 times. The powder after sufficient drying at 60°C is silicene.

[0022] (2) Preparation of silicene / graphene composites The prepared silicene is placed in a tubular furnace filled with a mixed gas of acetylene and argon (volume ratio of 1:19), heated from room temperature to 500°C at a rate of 5°C / min, and maintained at this temperature for 2 hours. After the tubular furnace is naturally cooled, the silicene / graphene composite material can be obtained.

[0023] The scanning electron microscope image of the prepared silicene / graphene composite material is shown in Figure 1 As shown, an obvious layered structure is found on the surface of the silicene / graphene composite structure, which corresponds to the staggered stacking of graphene and silicene.

[0024] like Figure 2 As shown, X-ray diffraction shows that the main diffraction peak of the silicene / graphene composite material corresponds to Si, indicating that CaSi2 has been topologically converted into silicene; in addition, the amorphous peak located near 30° corresponds to in-situ generated carbon, indicating that the silicene / graphene composite material has been successfully prepared.

[0025] Example 2

[0026] Solution configuration: 0.05 mol / L calcium silicide acetonitrile solution (40 mL): Take 0.192 g of calcium silicide and add it to 40 mL of acetonitrile. Stir thoroughly to make the calcium silicide evenly dispersed in the acetonitrile solution.

[0027] 0.2 mol / L nickel nitrate acetonitrile solution (40 mL): Take 1.462 g of nickel nitrate into 40 mL of acetonitrile and stir thoroughly to make the nickel nitrate evenly dispersed in the acetonitrile solution. A method for preparing a silicene / graphene composite material, the specific steps are as follows: (1) Synthesis of silicene First, add 40 mL of 0.2 mol / L nickel nitrate solution in acetonitrile to 40 mL of 0.05 mol / L calcium silicide solution in acetonitrile under constant stirring. Stir for two weeks, then filter and rinse with acetonitrile 4 to 5 times. The powder after sufficient drying at 50°C is silicene.

[0028] (2) Preparation of silicene / graphene composites The prepared silicene is placed in a tubular furnace filled with a mixed gas of acetylene and argon (volume ratio of 1:18), heated from room temperature to 500°C at a rate of 5°C / min, and maintained at this temperature for 2 hours. After the tubular furnace is naturally cooled, the silicene / graphene composite material can be obtained.

[0029] Example 3

[0030] Solution configuration: 0.1 mol / L calcium silicide acetonitrile solution (40 mL): Take 0.384 g of calcium silicide and add it to 40 mL of acetonitrile. Stir thoroughly to make the calcium silicide evenly dispersed in the acetonitrile solution.

[0031] 0.5 mol / L nickel nitrate acetonitrile solution (40 mL): Take 3.655 g of nickel nitrate and add it to 40 mL of acetonitrile. Stir thoroughly to make the nickel nitrate evenly dispersed in the acetonitrile solution. A method for preparing a silicene / graphene composite material, the specific steps are as follows: (1) Synthesis of silicene First, add 40 mL of 0.5 mol / L nickel nitrate solution in acetonitrile to 40 mL of 0.1 mol / L calcium silicide solution in acetonitrile under constant stirring. Stir continuously for two weeks, then filter and rinse with acetonitrile 4 to 5 times. The powder after sufficient drying at 70°C is silicene.

[0032] (2) Preparation of silicene / graphene composites The prepared silicene is placed in a tubular furnace filled with a mixed gas of acetylene and argon (volume ratio of 1:20), heated from room temperature to 500°C at a rate of 5°C / min, and maintained at this temperature for 2 hours. After the tubular furnace is naturally cooled, the silicene / graphene composite material can be obtained.

[0033] The above are preferred implementation modes of the present invention. Those skilled in the art to which the present invention belongs can also change and modify the above implementation modes. Therefore, the present invention is not limited to the above specific implementation modes. Any obvious improvements, substitutions or modifications made by those skilled in the art on the basis of the present invention belong to the protection scope of the present invention.

Claims

1. A method for preparing a silicene / graphene composite material, characterized in that: Here are the steps: S1. Preparation of silicene: Calcium silicide is added to acetonitrile, and stirred thoroughly to make the calcium silicide evenly dispersed in the acetonitrile solution. Then, an acetonitrile solution of a transition metal inorganic salt is added thereto under continuous stirring. After stirring for one to two weeks, the sample is collected by filtration and washed with acetonitrile several times. The obtained product is silicene after being fully dried. S2. Preparation of silicene / graphene composite material: Place the prepared silicene in a tubular furnace, and in a mixed atmosphere of acetylene and argon, heat the silicene to 500°C at a rate of 5°C / min, and maintain at this temperature for 2h. After natural cooling, the silicene / graphene composite material can be obtained.

2. The method for preparing the silicene / graphene composite material according to claim 1, characterized in that: In step S1, the transition metal inorganic salt is nickel nitrate.

3. The method for preparing the silicene / graphene composite material according to claim 2, characterized in that: The concentration of nickel nitrate in acetonitrile solution is 0.2~0.5mol / L.

4. The method for preparing the silicene / graphene composite material according to claim 2, characterized in that: The concentration of calcium silicide in acetonitrile solution is 0.05~0.1mol / L.

5. The method for preparing the silicene / graphene composite material according to claim 1, characterized in that: In step S1, the product is dried at a temperature of 50-70°C.

6. The method for preparing the silicene / graphene composite material according to claim 1, characterized in that: In step S2, the volume ratio of acetylene to argon is 1:(18-20).

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