Method for preparing carbon nanofiber

Abstract

The invention relates to a method for preparing carbon nanofibers (CNFs). The method is to control the diameter size of the carbon nanofiber by an external direct current electric field in a chemical vapor deposition system. The method comprises the following steps: firstly, plating a nickel nanocrystal film on the surface of a prepared substrate by numerical control double-pulsing electrodeposition technology; secondly, placing the electrodeposited substrate and an electrode in a uniform temperature zone of a furnace chamber of the chemical vapor deposition system, and sealing the furnace chamber; thirdly, introducing Ar gas; fourthly, heating the furnace chamber to 600 DEG C; and finally, preparing the carbon nanofibers with uniform diameter under the action of the external direct current electric field. The carbon nanofiber is synthesized by a common CVD system, and has strong practicality; the external electric field is a simple device, and can be operated and controlled easily. Furthermore, the method not only can effectively control the diameter size of the carbon nanofibers (CNFs), but also can lead the diameter size of the carbon nanofibers to be more uniform.

Description

technical field

[0001] The invention belongs to the field of preparation of inorganic materials, in particular to a method for preparing carbon nanofibers (CNFs). Background technique

[0002] Carbon nanofibers (CNFs) with a diameter of 10-100 nm are a new kind of nanomaterials. In addition to the characteristics of general micron-scale carbon fibers, such as low density, high specific strength, high specific modulus, high electrical and thermal conductivity, etc., it also has the advantages of small number of defects, large specific surface area, and compact structure. Carbon nanofibers (CNFs) provide an ideal substitute for the current difficulty in preparing graphite whiskers in large quantities. In addition, carbon nanofibers (CNFs) have great potential in the fields of catalysts, catalyst supports, anode materials for lithium-ion secondary batteries, electrodes for electric double-layer capacitors, high-efficiency adsorbents, separators, super composite materials, hydr...

Examples

Embodiment 1

[0026] Example 1: After the deposited substrate numbered M2 was placed in the CVD uniform temperature zone, the furnace chamber was closed, and Ar gas was introduced at a flow rate of 200 sccm, and heated to 600° C. after 40 minutes. At this time, an external electric field is introduced, and the substrate is connected to the negative electrode of the electric field, and the electric field intensity is kept constant at 25000V / m. Inject C at a flow rate of 30 sccm 2 h 2 Gas, the reaction starts and lasts for 3 minutes; after the reaction is completed, turn off the C 2 h 2 Remove the external electric field from the gas valve, and take it out after cooling to room temperature under the protection of Ar gas. The obtained carbon nanofiber transmission electron microscope (TEM) picture and diameter distribution figure are shown in figure 2 ,Such as figure 2 As shown, the average diameter is 13.8nm, and the standard error is 4.7nm.

Embodiment 2

[0027] Example 2: Apply an electric field of 50000 V / m to the deposited substrate numbered M3 (other experimental conditions are the same as in Example 1). The obtained carbon nanofiber transmission electron microscope (TEM) picture and diameter distribution figure are shown in image 3 ,Such as image 3 As shown, the average diameter is 8.0 nm, and the standard error is 2.4 nm.

Embodiment 3

[0028] Example 3: As a comparison, the deposited substrate numbered M1 was also put into CVD, and the experimental conditions were the same as in Example 1, but no electric field was added during the preparation process. The obtained carbon nanofiber transmission electron microscope (TEM) picture and diameter distribution figure are shown in figure 1 ,Such as figure 1 As shown, the average diameter is 19.2 nm, and the standard error is 8.6 nm.

[0029] It can be seen from the above that with the increase of the applied electric field, the average diameter of CNFs and the diameter distribution range are gradually reduced, that is, the purpose of controlling the diameter of CNFs is achieved.

technical field

[0001] The invention belongs to the field of preparation of inorganic materials, in particular to a method for preparing carbon nanofibers (CNFs). Background technique

[0002] Carbon nanofibers (CNFs) with a diameter of 10-100 nm are a new kind of nanomaterials. In addition to the characteristics of general micron-scale carbon fibers, such as low density, high specific strength, high specific modulus, high electrical and thermal conductivity, etc., it also has the advantages of small number of defects, large specific surface area, and compact structure. Carbon nanofibers (CNFs) provide an ideal substitute for the current difficulty in preparing graphite whiskers in large quantities. In addition, carbon nanofibers (CNFs) have great potential in the fields of catalysts, catalyst supports, anode materials for lithium-ion secondary batteries, electrodes for electric double-layer capacitors, high-efficiency adsorbents, separators, super composite materials, hydr...

Examples

Embodiment 1

[0026] Example 1: After the deposited substrate numbered M2 was placed in the CVD uniform temperature zone, the furnace chamber was closed, and Ar gas was introduced at a flow rate of 200 sccm, and heated to 600° C. after 40 minutes. At this time, an external electric field is introduced, and the substrate is connected to the negative electrode of the electric field, and the electric field intensity is kept constant at 25000V / m. Inject C at a flow rate of 30 sccm 2 h 2 Gas, the reaction starts and lasts for 3 minutes; after the reaction is completed, turn off the C 2 h 2 Remove the external electric field from the gas valve, and take it out after cooling to room temperature under the protection of Ar gas. The obtained carbon nanofiber transmission electron microscope (TEM) picture and diameter distribution figure are shown in figure 2 ,Such as figure 2 As shown, the average diameter is 13.8nm, and the standard error is 4.7nm.

Embodiment 2

[0027] Example 2: Apply an electric field of 50000 V / m to the deposited substrate numbered M3 (other experimental conditions are the same as in Example 1). The obtained carbon nanofiber transmission electron microscope (TEM) picture and diameter distribution figure are shown in image 3 ,Such as image 3 As shown, the average diameter is 8.0 nm, and the standard error is 2.4 nm.

Embodiment 3

[0028] Example 3: As a comparison, the deposited substrate numbered M1 was also put into CVD, and the experimental conditions were the same as in Example 1, but no electric field was added during the preparation process. The obtained carbon nanofiber transmission electron microscope (TEM) picture and diameter distribution figure are shown in figure 1 ,Such as figure 1 As shown, the average diameter is 19.2 nm, and the standard error is 8.6 nm.

[0029] It can be seen from the above that with the increase of the applied electric field, the average diameter of CNFs and the diameter distribution range are gradually reduced, that is, the purpose of controlling the diameter of CNFs is achieved.

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