A method for preparing a silicene / graphene composite

Abstract

The present application relates to the technical field of material preparation, and particularly relates to a preparation method of silicene / graphene composite material, which comprises the following steps: adding calcium silicide into acetonitrile, stirring to uniformly disperse the calcium silicide in the acetonitrile solution, then adding acetonitrile solution of transition metal inorganic salt into the solution under continuous stirring, filtering and collecting the sample after stirring for one to two weeks, washing the sample with acetonitrile for several times, and fully drying the obtained product to obtain the silicene; placing the prepared silicene in a tube furnace, heating the silicene to 500 DEG C at a rate of 5 DEG C / min under the mixed atmosphere of acetylene and argon, keeping the temperature for 2h, and naturally cooling to obtain the silicene / graphene composite material. The present application utilizes the weak oxidizability of transition metal ions, topologically converts the calcium silicide into silicene through the original site replacement reaction, further takes the metal element produced in the replacement reaction as a catalyst, and converts acetylene into graphene under heating condition, so that the preparation process of the silicene / graphene composite material is simplified.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of material preparation, and particularly relates to a preparation method of a silicene / graphene composite material. BACKGROUND

[0002] Because of the extremely high theoretical specific capacity (4200 mA h g -1 ) and the low lithium intercalation voltage (0.2-0.3 V vs .Li / Li + ), silicon is a very promising anode material for lithium-ion batteries. However, due to the huge volume change during the lithium extraction / intercalation process and the poor electronic conductivity, the cycle life and rate performance of the silicon anode are poor, which seriously hinders the practical application of the silicon anode. The structure of two-dimensional silicene is similar to that of graphene, has a honeycomb lattice structure and weak interlayer van der Waals force, and the large interlayer space enables the silicene to have sufficient space to adsorb and migrate lithium ions, effectively preventing the breaking of the covalent bond and the collapse of the structure of the silicon during the lithium extraction / intercalation process, thereby improving the cycle stability of the silicon anode. The silicene prepared by epitaxial growth as a lithium-ion battery anode material exhibits excellent cycle stability and rate performance. At present, there are few studies on the combination of silicene and graphene materials.

[0003] Chinese Patent Publication No. CN118908149A discloses a preparation method and application of a 3D printed silicene-based composite structure material, 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 needs ultrasonic dispersion to obtain a high concentration fluid. The preparation process is complex. SUMMARY

[0004] The application solves the problems in the related art and provides a preparation method of a silicene / graphene composite material. Calcium silicide is used as a raw material, the weak oxidizing property of transition metal ions is used, the calcium silicide is topologically converted into silicene through a replacement reaction, the metal element generated in the replacement reaction is used as a catalyst, and acetylene is converted into graphene under heating. Since the metal element is distributed in the interlayer of the silicene, the graphene generated by catalysis is also distributed in the interlayer of the silicene, and a silicene / graphene composite structure is formed. The structural characteristics of the calcium silicide are fully utilized, the in-situ generated metal element is ingeniously used, and the preparation process of the silicene / graphene composite material is simplified.

[0005] To solve the above technical problems, the application is implemented by the following technical scheme: a preparation method of a silicene / graphene composite material, and the steps are as follows:

[0006] S1, preparation of silicene: calcium silicide is added into acetonitrile, and the calcium silicide is uniformly dispersed in the acetonitrile solution by stirring, then the acetonitrile solution of transition metal inorganic salt is added into the solution under continuous stirring, the sample is collected after stirring for one to two weeks, and washed with acetonitrile for several times, and the obtained product is dried to obtain silicene;

[0007] S2, preparation of silicene / graphene composite material: the prepared silicene is placed in a tube furnace, and the silicene is heated to 500℃ at a rate of 5℃ / min under the mixed atmosphere of acetylene and argon, and is kept at the temperature for 2h, and the silicene / graphene composite material is obtained after natural cooling.

[0008] As a preferred solution, in step S1, the transition metal inorganic salt is nickel nitrate.

[0009] As a preferred solution, the concentration of the acetonitrile solution of nickel nitrate is 0.2-0.5mol / L.

[0010] As a preferred solution, the concentration of the acetonitrile solution of calcium silicide is 0.05-0.1mol / L.

[0011] As a preferred solution, in step S1, the temperature for drying the product is 50-70℃.

[0012] As a preferred solution, in step S2, the volume ratio of acetylene to argon is 1: (18-20).

[0013] Compared with the prior art, the present application has the following beneficial effects: the present application uses calcium silicide as raw material, utilizes the weak oxidizing property of transition metal ions, and topologically converts the calcium silicide into silicene through a replacement reaction, and further uses the metal element generated in the replacement reaction as a catalyst to convert acetylene into graphene under heating conditions, and since the metal element is distributed between the layers of the silicene, the catalytically generated graphene is also distributed between the layers of the silicene, forming a silicene / graphene composite structure; the present application fully utilizes the structural characteristics of calcium silicide, and ingeniously uses the in-situ generated metal element, and simplifies the preparation process of the silicene / graphene composite material. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a scanning electron microscope image of the silicene / graphene composite material of the present application;

[0015] Figure 2 is an X-ray diffraction pattern of the silicene / graphene composite material of the present application. DETAILED DESCRIPTION

[0016] Clearly, only the embodiments described are merely a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one example embodiment is merely illustrative in nature and is in no way intended to limit the application or its applications or uses. Based upon the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort are within the scope of the present application.

[0017] It is to be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, devices, components and / or combinations thereof, but do not preclude the presence or addition of one or more other features, steps, operations, devices, components and / or combinations thereof.

[0018] The relative arrangement of parts and steps, numerical expressions, and numerical values set forth in the examples are not intended to limit the scope of the application, unless otherwise specifically stated. It is to be understood that the drawings are not necessarily to scale as the dimensions of the parts shown are for the purpose of illustration and description only. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art can not be discussed in detail, but are to be considered as part of the description of the application. In all examples shown and discussed herein, any specific values are to be interpreted as illustrative only and not as a limitation. Thus, other examples of the example embodiments can have different values. It is to be noted that like reference numerals and letters refer to like items in the following drawings, and thus, once an item is defined in one drawing, it need not be discussed further in subsequent drawings.

[0019] In the description of the application, it should be understood that the orientation words such as "front, back, up, down, left, right", "horizontal, vertical, perpendicular, horizontal" and "top, bottom" and the like indicated orientation or position relationship are generally based on the orientation or position relationship shown in the drawings, only for the convenience of describing the application and simplifying the description, without the opposite indication, these orientation words do not indicate and imply that the indicated device or element must have a specific orientation or be constructed and operated in a specific orientation, therefore, it cannot be understood as a limitation on the scope of protection of the application; the orientation words "inner, outer" refer to the inner and outer relative to the contour of each component.

[0020] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0021] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0022] Example 1

[0023] Solution preparation:

[0024] 0.075 mol / L calcium silicide acetonitrile solution (40 mL): Add 0.288 g of calcium silicide to 40 mL of acetonitrile and stir thoroughly to ensure that the calcium silicide is evenly dispersed in the acetonitrile solution.

[0025] 0.3 mol / L nickel nitrate acetonitrile solution (40 mL): Add 2.192 g of nickel nitrate to 40 mL of acetonitrile, and stir thoroughly to ensure the nickel nitrate is evenly dispersed in the acetonitrile solution.

[0026] A method for preparing a silicene / graphene composite material, the specific steps of which are as follows:

[0027] (1) Synthesis of silicene

[0028] First, while stirring continuously, add 40 mL of nickel nitrate acetonitrile solution with a concentration of 0.3 mol / L to 40 mL of calcium silicide acetonitrile solution. After stirring continuously for two weeks, filter and wash with acetonitrile 4-5 times. The powder obtained after being fully dried at 60°C is silane.

[0029] (2) Preparation of silicene / graphene composite materials

[0030] The prepared silicene was placed in a tube furnace filled with a mixture of acetylene and argon gas (volume ratio of 1:19), heated from room temperature to 500°C at a rate of 5°C / min, and kept at this temperature for 2 hours. After the tube furnace was naturally cooled, the silicene / graphene composite material was obtained.

[0031] The scanning electron microscope image of the prepared silicene / graphene composite material is shown in FIG. 1. On the surface of the silicene / graphene composite structure, a clear layered structure corresponding to the interleaved stacking of graphene and silicene was found. Figure 1

[0032] As shown in FIG. 2, X-ray diffraction of the silicene / graphene composite material showed that the main diffraction peaks corresponded to Si, indicating that CaSi2 had topologically transformed into silicene; in addition, the amorphous peak near 30° corresponded to the in-situ generated carbon, indicating that the silicene / graphene composite material had been successfully prepared. Figure 2

[0033] Example 2

[0034] Solution configuration:

[0035] 0.05 mol / L calcium silicide acetonitrile solution (40 mL): 0.192 g of calcium silicide was taken into 40 mL of acetonitrile, and the calcium silicide was uniformly dispersed in the acetonitrile solution by stirring to obtain the solution.

[0036] 0.2 mol / L nickel nitrate acetonitrile solution (40 mL): 1.462 g of nickel nitrate was taken into 40 mL of acetonitrile, and the nickel nitrate was uniformly dispersed in the acetonitrile solution by stirring to obtain the solution.

[0037] A method for preparing a silicene / graphene composite material, the specific steps are as follows:

[0038] (1) Synthesis of silicene

[0039] First, 40 mL of 0.05 mol / L calcium silicide acetonitrile solution was added to 40 mL of 0.2 mol / L nickel nitrate acetonitrile solution under constant stirring, and after two weeks of continuous stirring, the mixture was filtered and washed with acetonitrile 4-5 times. The powder dried at 50°C was silicene.

[0040] (2) Preparation of silicene / graphene composite material

[0041] The prepared silicene was placed in a tube furnace filled with a mixture of acetylene and argon gas (volume ratio of 1:18), heated from room temperature to 500°C at a rate of 5°C / min, and kept at this temperature for 2 hours. After the tube furnace was naturally cooled, the silicene / graphene composite material was obtained.

[0042] Example 3​​

[0043] Solution configuration:

[0044] 0.1 mol / L calcium silicide acetonitrile solution (40 mL): 0.384 g of calcium silicide was taken into 40 mL of acetonitrile, and the calcium silicide was uniformly dispersed in the acetonitrile solution by stirring, thereby obtaining the solution.

[0045] 0.5 mol / L nickel nitrate acetonitrile solution (40 mL): 3.655 g of nickel nitrate was taken into 40 mL of acetonitrile, and the nickel nitrate was uniformly dispersed in the acetonitrile solution by stirring, thereby obtaining the solution.

[0046] A preparation method of a silicene / graphene composite material, and the specific steps are as follows:

[0047] (1) Synthesis of silicene

[0048] First, 40 mL of 0.1 mol / L calcium silicide acetonitrile solution was added to 40 mL of 0.5 mol / L nickel nitrate acetonitrile solution under continuous stirring, and after continuous stirring for two weeks, the mixture was filtered and washed with acetonitrile for 4-5 times, and the powder dried at 70°C was silicene.

[0049] (2) Preparation of silicene / graphene composite material

[0050] The prepared silicene was placed in a tube furnace filled with a mixture of acetylene and argon gas (volume ratio of 1:20), heated from room temperature to 500°C at a rate of 5°C / min, and kept at the temperature for 2 hours, and after the tube furnace was naturally cooled, a silicene / graphene composite material was obtained.

[0051] The above is a preferred embodiment of the present application, and those skilled in the art can also make changes and modifications to the above embodiment, therefore, the present application is not limited to the above specific embodiments, and any obvious improvements, replacements or modifications made by those skilled in the art on the basis of the present application are within the protection scope of the present application.

Claims

1. A method of preparing a silicene / graphene composite material, characterized by: The steps are as follows: S1, preparation of silicene: calcium silicide is added into acetonitrile, and the calcium silicide is uniformly dispersed in the acetonitrile solution by fully stirring to obtain an acetonitrile solution of calcium silicide with a concentration of 0.05-0.1 mol / L, then nickel nitrate acetonitrile solution is added thereto under continuous stirring, the concentration of the nickel nitrate acetonitrile solution is 0.2-0.5 mol / L, the sample is collected after stirring for one to two weeks, and is washed with acetonitrile for several times, and the obtained product is fully dried to obtain silicene; S2, preparation of silicene / graphene composite material: the prepared silicene is placed in a tube furnace, the silicene is heated to 500℃ at a rate of 5℃ / min under the mixed atmosphere of acetylene and argon, and is kept at the temperature for 2h, and the silicene / graphene composite material is obtained after natural cooling.

2. The method of claim 1, wherein: In step S1, the temperature for drying the product is 50-70℃.

3. The method of claim 1, wherein: In step S2, the volume ratio of acetylene to argon is 1: (18-20).

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