CN114380286B - Needle-like carbon nanotube for encapsulating magnetic particles and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of composite materials, in particular to a needle-shaped carbon nanotube for encapsulating magnetic particles and a preparation method thereof. The carbon nanotube of the present invention has needle shape, and features that the carbon nanotube has thick end of 140-220 nm diameter and thin end of 35-65 nm diameter, and the needle shape carbon nanotube has length of 1.5-4.0 micron and magnetic particle packed inside. The preparation method comprises the following steps: dissolving a catalyst precursor ferric salt in a solvent, adding a carbon source, stirring, evaporating the solvent to obtain a mixture powder of the catalyst and the carbon source, heating the mixture to a set temperature in a flowing inert atmosphere, and preserving the temperature for a certain time at the set temperature to obtain black powder which is needle-shaped carbon nano tubes for encapsulating magnetic particles, wherein the morphology of the carbon nano tubes can be regulated and controlled by changing the gas flow rate, the preserving temperature and the mass ratio of the catalyst to the carbon source in the heating and preserving processes.

Description

A needle-shaped carbon nanotube encapsulating magnetic particles and its preparation method

technical field

The invention belongs to the technical field of composite materials, in particular to the technical field of carbon nanotube preparation, in particular to a needle-shaped carbon nanotube encapsulating magnetic particles and a preparation method thereof.

Background technique

Carbon nanotubes are one-dimensional nanomaterials with excellent mechanical properties, chemical stability, electrical conductivity, and thermal conductivity. Their ideal structures play an important role in the fields of mechanics, electricity, and heat. Chemistry, biology, physics, or some interdisciplinary subjects also have broad application prospects, specifically applicable to optical sensors, electrode materials, flat panel displays, and wave-absorbing materials. In order to further improve the performance of carbon nanotubes, researchers have prepared carbon nanotubes of different shapes through various methods, and have achieved important results in many fields. How to use simple and low-cost preparation methods to realize the carbon nanotubes Controllable growth is the key to push carbon nanotubes into diversified applications.

The current carbon nanotube preparation methods include arc discharge method, laser ablation method, chemical vapor deposition method and so on. The arc discharge method is to use high-purity graphene as the cathode and anode. When the arc discharge occurs between the two electrodes, the high temperature generated will gasify the anode. The carbon decomposed by gasification will form a ring, and finally form carbon nanotubes. In the cathode, but this method is cumbersome and complicated, and the purity of the generated carbon nanotubes is extremely low, which must undergo subsequent purification treatment, which is not suitable for mass production. The laser ablation method uses a laser beam to bombard a graphene target, and after gasification, it is deposited on the surface of a conical water-cooled copper tube under the carrying of an inert atmosphere to form carbon nanotubes. The low yield of this method is not conducive to large-scale production, and it is safe. Hidden danger and can not accurately control the diameter and length of carbon nanotubes. Chemical vapor deposition is a method that is widely used at present. It first deposits a layer of catalyst substrate, and then passes in gas as a carbon source. Using high temperature, the carbon source gas is decomposed and contacted with the catalyst, and catalyzed to form carbon nanotubes. This preparation method is complicated to operate and the cost of the deposition system is high, which is not conducive to practical application. Therefore, it is necessary to provide a preparation method of carbon nanotubes with simple operation, low cost, suitable for large-scale production and controllable morphology and structure.

Contents of the invention

In order to solve the deficiencies of the prior art, the present invention provides a needle-shaped carbon nanotube encapsulating magnetic particles and a preparation method thereof, and the adopted technical scheme is:

A needle-shaped carbon nanotube encapsulating magnetic particles, which is needle-shaped in shape, 1.5-4.0 μm in length, has a thick end and a thin end, the diameter of the thick end is 140-220 nm, and the diameter of the thin end is 35-65 nm. Magnetic particles are encapsulated within carbon nanotubes.

Further, the magnetic particles are ellipsoidal, and the particle size length is 250-400nm;

Further, the particle diameter width of the magnetic particles is 130-210 nm;

Further, the magnetic particles are Fe and/or Fe ₃ C.

A method for preparing needle-shaped carbon nanotubes encapsulating magnetic particles, comprising the following specific steps:

(1) Dissolving the catalyst precursor iron salt in a solvent, adding a carbon source and stirring, evaporating the solvent to obtain a mixture powder;

(2) The mixture powder in step (1) is heated up to a set temperature under an inert gas flow atmosphere and kept warm to obtain a black powder that is acicular carbon nanotubes encapsulating magnetic particles.

Further, the mass ratio of the catalyst precursor iron salt and the carbon source in step (1) is 5:4 to 4:5;

Further, the mass volume ratio of the catalyst precursor iron salt to the solvent is 1:10˜1:50 g/mL.

Further, the catalyst precursor iron salt described in step (1) is selected from ferric chloride hexahydrate and/or iron acetylacetonate;

Further, the carbon source is selected from melamine;

Further, the solvent is selected from ethanol and/or deionized water.

Further, the inert gas in step (2) is selected from nitrogen or argon.

Further, the flow rate of the inert gas in step (2) is 60-300 mL/min.

Further, the heating rate of the heat preservation in step (2) is 5-10° C./min.

Further, the holding temperature described in step (2) is 700-950°C;

Further, the holding time is 3-6 hours.

Further, in step (1), the dissolution temperature of the catalyst precursor iron salt dissolved in the solvent is 40-80°C;

Further, the evaporation temperature is 40-80°C.

The beneficial effects that the present invention obtains are:

(1) The present invention discloses a needle-shaped carbon nanotube for encapsulating magnetic particles. ～220nm, the diameter of the thin end is 35～65nm, and the thick end is encapsulated with magnetic particles. The specific formation process is as follows: first, the iron ions in the iron salt are reduced to iron as the catalytic center, and through the catalysis of iron particles, the carbon-containing gas decomposed from the carbon source grows on the surface of the catalyst to form the initial carbon nanotubes, because the gas flow rate is large , the size of the initially formed catalyst center particles is small, so the initially formed carbon nanotubes are thin ends. The diameter of the tube also becomes larger, so acicular carbon nanotubes with thick ends and thin ends are formed. Because of the different diameters of the needle-shaped carbon nanotubes, they will have different response frequencies to the electromagnetic wave absorption process. , so it can effectively improve the qualified absorption bandwidth of electromagnetic waves, and has excellent wave-absorbing performance, so it can be applied to electromagnetic wave absorption. In addition, the carbon nanotubes also have excellent magnetic properties, electrical conductivity, thermal conductivity and photoelectric response properties, so It can also be applied to fields such as electrode materials, catalysis, and conductive and heat-conducting materials.

(2) The present invention provides a kind of preparation method of the acicular carbon nanotube of encapsulating magnetic particles, the catalyst precursor iron salt is heated and dissolved in solvent, carbon source is added and stirred, after evaporating solvent, obtain mixture powder, then in Heat up and keep warm under inert gas flow atmosphere, and the black powder is needle-shaped carbon nanotubes. Encapsulated magnetic particles can be obtained by simple mixing and heat preservation treatment under inert gas flow atmosphere by using cheap and easy-to-obtain catalyst precursor iron salt and carbon source needle-shaped carbon nanotubes, the method has the advantages of easy control of the operation method, high safety factor, low equipment requirements, low cost, simple process, and no need for flammable and explosive gases, so it is suitable for large-scale production. The encapsulated magnetic The needle-like carbon nanotubes of particles have good stability and controllable morphology and structure. The final morphology of carbon nanotubes can be regulated by changing the gas flow rate, temperature control process, and mass ratio of catalyst to carbon source, which has broad application prospects.

Description of drawings

Fig. 1 is the scanning electron micrograph of the acicular carbon nanotubes of encapsulating magnetic particles obtained in Example 19;

Fig. 2 is the transmission electron micrograph of the acicular carbon nanotubes of encapsulating magnetic particles obtained in Example 19;

Fig. 3 is the X-ray diffraction spectrum of the acicular carbon nanotubes of encapsulating magnetic particles obtained in Example 19;

Fig. 4 is the hysteresis loop at room temperature of the acicular carbon nanotubes encapsulating magnetic particles obtained in Example 19;

FIG. 5 is a graph of the absorption curve of the acicular carbon nanotubes encapsulating magnetic particles obtained in Example 19. FIG.

Example

In order to understand the present invention more clearly, the present invention will now be further described with reference to the following examples and accompanying drawings. The examples are for illustration only and do not limit the invention in any way. In the examples, each original reagent material can be obtained commercially, and the experimental methods without specific conditions are conventional methods and conventional conditions well known in the art, or according to the conditions suggested by the instrument manufacturer.

Example 1

(1) Weigh 3.0g of ferric chloride hexahydrate and dissolve it in 30mL of ethanol solution, place it in an oil bath at 60°C, add 3.0g of melamine after the ferric chloride hexahydrate is completely dissolved, and stir the mixture thoroughly with magnetic force. Dry in an oven at 60°C for 24 hours to obtain an orange powder;

(2) Place the orange-yellow powder prepared in step (1) in a container, put it into the temperature-controlled area of the tube furnace, and under nitrogen atmosphere (gas flow rate 60mL/min), the heating rate is 5°C/min. Heat at 700°C for 3 hours, and cool to room temperature to obtain black powder, which is needle-shaped carbon nanotubes.

Example 2

The difference between this embodiment and Example 1 is that ferric chloride hexahydrate is used instead of iron acetylacetonate in step (1), and other steps and parameters are the same as in Example 1.

Example 3

The difference between this embodiment and embodiment 1 is that the ethanol solution in step (1) is changed to deionized water, and other steps and parameters are the same as in embodiment 1.

Example 4

The present embodiment differs from Example 1 in that the amount of ferric chloride hexahydrate in step (1) is 2.4g, and other steps and parameters are the same as in Example 1.

Example 5

The difference between this embodiment and Example 1 is that the amount of melamine in step (1) is 2.4g, and other steps and parameters are the same as in Example 1.

Example 6

The difference between this embodiment and embodiment 1 is that nitrogen is changed to argon in step (2), and other steps and parameters are the same as embodiment 1.

Example 7

The difference between this embodiment and embodiment 1 is that the gas flow rate in step (2) is 100mL/min, and other steps and parameters are the same as in embodiment 1.

Example 8

The difference between this embodiment and embodiment 1 is that the gas flow rate in step (2) is 150mL/min, and other steps and parameters are the same as in embodiment 1.

Example 9

The difference between this embodiment and embodiment 1 is that the gas flow rate in step (2) is 200mL/min, and other steps and parameters are the same as in embodiment 1.

Example 10

The difference between this embodiment and embodiment 1 is that the gas flow rate in step (2) is 250mL/min, and other steps and parameters are the same as in embodiment 1.

Example 11

The difference between this embodiment and embodiment 1 is that the gas flow rate in step (2) is 300mL/min, and other steps and parameters are the same as in embodiment 1.

Example 12

The difference between this embodiment and embodiment 1 is that the heating rate in step (2) is 6° C./min, the temperature of the heat preservation is 900° C., and other steps and parameters are the same as in embodiment 1.

Example 13

The difference between this embodiment and embodiment 1 is that the heating rate in step (2) is 10°C/min, the holding temperature is 950°C, and other steps and parameters are the same as in embodiment 1.

Example 14

The difference between this embodiment and embodiment 2 is that the step (2) is heated to 800° C., and other steps and parameters are the same as in embodiment 2.

Example 15

The difference between this embodiment and embodiment 3 is that in step (2), it is heated to 800° C., and other steps and parameters are the same as in embodiment 3.

Example 16

The difference between this embodiment and embodiment 4 is that the step (2) is heated to 800° C., and other steps and parameters are the same as in embodiment 4.

Example 17

The difference between the present embodiment and the embodiment 5 is that the step (2) is heated to 800° C., and other steps and parameters are the same as the embodiment 5.

Example 18

The difference between this embodiment and embodiment 6 is that in step (2), it is heated to 800° C., and other steps and parameters are the same as in embodiment 6.

Example 19

The difference between this embodiment and embodiment 7 is that in step (2), it is heated to 800° C., and other steps and parameters are the same as embodiment 7.

Example 20

The difference between this embodiment and embodiment 1 is that the heat preservation time in step (2) is 4h, and other steps and parameters are the same as embodiment 1.

Example 21

The difference between this embodiment and embodiment 1 is that the heat preservation time in step (2) is 5h, and other steps and parameters are the same as embodiment 1.

Example 22

The difference between this embodiment and Example 1 is that the holding time in step (2) is 6 hours, the holding temperature is 800° C., and other steps and parameters are the same as in Example 1.

The acicular carbon nanotubes encapsulating magnetic particles obtained in Example 19 can be seen from Figures 1 and 2, the obtained acicular carbon nanotubes have a uniform appearance and an average length of about 3 μm, and the average length of the coated magnetic particles is about The average particle diameter is about 170nm, the average diameter of the thick end of the carbon nanotube is about 185nm, and the average diameter of the thin end of the carbon nanotube is about 46nm.

It can be seen from Fig. 3 that the obtained X-ray diffraction peaks of the needle-shaped carbon nanotubes detected the characteristic peaks of Fe and Fe ₃ C, and the peak at 26° was assigned to C.

It can be seen from Figure 4 that the saturation magnetization and coercivity of the obtained needle-like carbon nanotubes are 50.57emu/g and 140O, respectively.

It can be seen from FIG. 5 that the obtained acicular carbon nanotubes have an effective absorption bandwidth of 5.20 GHz for electromagnetic waves, and can effectively absorb electromagnetic waves in the frequency range of 15-18 GHz.

Apparently, the above-mentioned embodiments are only examples for clearly illustrating, rather than limiting the embodiments. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the embodiments here. And the obvious changes or changes derived therefrom are still within the scope of protection of the present invention.

Claims (4)

1. The needle-shaped carbon nano tube for encapsulating the magnetic particles is characterized in that the needle-shaped carbon nano tube for encapsulating the magnetic particles is needle-shaped, has a length of 1.5-4.0 mu m and has a thick end and a thin end, the diameter of the thick end is 140-220 nm, the diameter of the thin end is 35-65 nm, and the magnetic particles are encapsulated in the needle-shaped carbon nano tube;

the magnetic particles are ellipsoidal, and the particle size length of the magnetic particles is 250-400 nm;

the particle size width of the magnetic particles is 130-210 nm;

the magnetic particles are Fe and/or Fe ₃ C。

2. The method for preparing the needle-shaped carbon nano tube for encapsulating the magnetic particles as claimed in claim 1, which is characterized by comprising the following specific steps:

(1) Dissolving a catalyst precursor ferric salt in a solvent, adding a carbon source, stirring, and evaporating the solvent to obtain a mixture powder;

the mass ratio of the catalyst precursor ferric salt to the carbon source is 5:4~4:5, a step of;

the mass volume ratio of the catalyst precursor ferric salt to the solvent is 1:10-1:50 g/mL;

the catalyst precursor ferric salt is selected from ferric trichloride hexahydrate and/or ferric acetylacetonate;

the carbon source is selected from melamine;

the solvent is selected from ethanol and/or deionized water;

(2) Heating the mixture powder in the step (1) to a set temperature in an inert gas flowing atmosphere and preserving heat to obtain black powder, namely the needle-shaped carbon nano tube for encapsulating the magnetic particles;

the flow speed of the inert gas is 60-300 mL/min;

the temperature rising rate of the heat preservation is 5-10 ℃/min;

the heat preservation temperature is 700-950 ℃;

the heat preservation time is 3-6 hours.

3. The method of claim 2, wherein the inert gas in step (2) is selected from nitrogen and argon.

4. The preparation method according to claim 2, wherein the dissolution temperature of the catalyst precursor ferric salt dissolved in the solvent in the step (1) is 40-80 ℃;

the evaporating temperature is 40-80 ℃.

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