KR100729154B1 - Metal-doped shell-shaped carbon particles and preparation method thereof - Google Patents

Abstract

The present invention relates to metal-doped shell-shaped carbon particles and a method of manufacturing the same, comprising a plurality of layers connected to planar and curved graphitized layered structures according to the present invention and doped with metals having empty internal centers. The shell-shaped carbon particles have improved electrical and magnetic properties compared to the conventional carbon particles, and thus may be usefully used in various fields such as magnetic recording media, biomaterials, field emission devices, nanofluids, and superconducting materials.

Description

Metal-doped shell-shaped carbon particles and a method of manufacturing the same {METAL DOPED SHELL SHAPED CARBON PARTICLES AND PREPARING PROCESS THEREOF}

1 shows the shape of conventional amorphous carbon particles (amorphous carbon particles),

Figure 2 shows the shape of the conventional graphite (graphite) particles,

Figure 3 shows the shape of a conventional carbon nanotube (nanotube),

Figure 4 shows the shape of a conventional carbon fullerene (fullerene),

5 shows an example of an apparatus used for the production of metal-doped shell-shaped carbon particles according to the present invention,

FIG. 6 shows transmission electron microscopy (TEM) images at low and high magnifications of iron (Fe) -doped shell-shaped carbon particles prepared in Examples of the present invention.

FIG. 7 shows X-ray diffraction analysis results (a) and Raman spectroscopy results (b) of the iron (Fe) -doped shell-shaped carbon particles prepared in Examples.

FIG. 8 shows the results of electron paramagnetic resonance (EPR) and superconducting quantum interference device (SQUID) of iron (Fe) -doped shell-shaped carbon particles prepared in Examples.

FIG. 9 is a field electron emission test result of iron (Fe) -doped shell-shaped carbon particles prepared in Example.

10 is a transmission electron micrograph (a) and an X-ray diffraction analysis (b) of the platinum (Pt) -doped shell-shaped carbon particles prepared in Example,

11 is a transmission electron micrograph (a) and a magnetic property analysis result (b) of the manganese (Mn) -doped shell-shaped carbon particles prepared in Example,

12 shows transmission electron micrographs (a) and magnetic characterization results (b) of rubidium (Rb) -doped shell-shaped carbon particles prepared in Examples.

Description of the main parts of the drawing

1: nitrogen (N ₂ ) gas tank 2: acetylene (C ₂ H ₂ ) gas tank

3: ultrasonic nebulizer

4: metalorganic precursor solution

5: metal organic precursor droplet + acetylene gas

6: compressed air 7: burner

8: CO ₂ laser

9: CO ₂ laser beam stopper

10: metal-doped shell-shaped carbon particles

The present invention relates to metal-doped shell-shaped carbon particles and a method for producing the same.

Conventional carbon particles include amorphous char (amorphous soot), graphite (graphite), nanotube (nanotube), fullerene (fullerene). Among them, charcoal is crystalline and physically and chemically unstable (see FIG. 1), and graphite has plate crystals, but its strength and electrical and thermal conductivity are not good in the longitudinal direction (see FIG. 2). In addition, various carbon nanotubes (see FIG. 3) have a semi-dimensional structure with conductor or semiconductor properties depending on the degree of distortion of the structure, and exhibit a unique quantum effect. It can be sent and exhibits diamagnetism, which increases with decreasing temperature, and is electrically used as a field electron-emitting device, but the continuous stability of electron emission has become a problem. In addition, fullerene having a structure as shown in FIG. 4 is a material of a soccer ball-shaped molecule composed of 60 or 70 carbon atoms, and since it was discovered in 1985, thermal stability, semiconductivity, or superelectric conductivity has been reported. However, it is not easy to manufacture and is not popularized.

As described above, these conventional carbon particles show many disadvantages in terms of thermal stability, physical and chemical properties, and become a problem in generalization.

Accordingly, it is an object of the present invention to provide a carbon-doped carbon particles having a new structure with improved physical and chemical properties compared to conventional carbon particles.

In order to achieve the above object, the present invention provides a shell-shaped carbon particles doped with a metal to the carbon particles having a plurality of layers connected to the planar and curved graphitized layer structure and the hollow inner center.

In addition, the present invention includes a) supplying a ignition by supplying a hydrocarbon gas containing a metal-containing precursor material into the burner, b) irradiating a laser to the ignited flame, metal-doped shell-shaped carbon particles It provides a method for producing.

Hereinafter, the present invention will be described in more detail.

The present invention is characterized in that the carbon particles are manufactured in a hollow shell shape of a plurality of layers in which planar and curved graphitized layered structures are connected, but doped with various metals. Accordingly, the metal-doped carbon particles of the present invention have various magnetic and electrical properties and new properties not found in conventional carbon particles depending on the type of the doped metal component or by interaction with the carbon which is a known structure.

In the present invention, the metal which can be doped to the carbon particles is a transition metal such as scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, precious metals such as gold, silver, platinum, iridium, lithium, Alkali metals, such as sodium, potassium, rubidium, cesium, and francium, and mixtures thereof are mentioned.

In the present invention, the amount of metal doping to the carbon particles is in the range of about 1 to 50,000 ppm, and the amount of doping may vary depending on the use of the particles.

The metal-doped shell-shaped carbon particles according to the present invention preferably have a spherical shape and may have a particle diameter of 1 nm to 500 µm.

The preparation of the metal-doped shell-shaped carbon particles of the present invention can be performed, for example, as follows.

Specifically, first, the precursor containing the metal to be doped is converted into droplet form or gas form. Metal-containing precursors in the form of droplets can be prepared by dissolving an organic compound containing the metal to be doped in a solvent and then the resulting solution by conventional methods, for example by an ultrasonic nebulizer, wherein the metal-containing precursors in gaseous form are conventional methods. For example, metal compounds, such as iron pentacarbonyl, can be obtained by vaporizing by a bubbling method.

The metal-containing precursor material is supplied to the central portion of the burner by the transport gas together with the hydrocarbon gas which is the carbon precursor and ignited (step (a)). At this time, it is preferable to introduce a blocking gas to suppress the chemical reaction between the precursor and the outside air to the peripheral portion of the ignited flame, and supply compressed air to stabilize the flame. In this case, an inert gas such as nitrogen or argon may be used as the blocking gas.

Nitrogen, helium or argon may be used as the precursor carrier gas, and acetylene gas, ethylene gas or methane gas may be used as the hydrocarbon gas, and acetylene gas is preferable.

Representative examples of the metal-containing precursor compounds used in the present invention include iron acetyl acetonate, iron penta carbonyl, manganese acetyl acetonate, manganese chloride, cobalt acetyl acetonate and mixtures thereof as compounds for doping transition metals. The compounds for doping the noble metals include platinum acetyl acetonate, platinum chloride, gold chloride and mixtures thereof, and the compounds for doping alkali metals include rubidium acetyl acetonate, potassium chloride and mixtures thereof. Examples thereof include water, ethanol or methanol.

In the present invention, in supplying the metal-containing precursor material and the hydrocarbon gas into the burner, a transport gas including the metal-containing precursor material per 1 lpm (liter per minute) of hydrocarbon gas is supplied to 250 standard cubic centimeter per minute (SCCM). It is preferable to flow in the following amounts.

As described above, by irradiating a flame having a mixed precursor introduced therein with a high power laser, preferably a CO ₂ laser (step (b)), carbon particles doped with metal according to the present invention may be prepared.

According to the laser irradiation as described above, the carbon precursor chemically reacts with the metal-containing precursor to have a shell shape doped with a metal having carbon crystallinity.

As described above, according to the present invention, the shell-like carbon particles can be doped with high productivity, and thus can be usefully used for preparing carbon particles having various characteristics.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

Example 1 Preparation of Iron-Doped Shell Shaped Carbon Particles

In the apparatus as shown in Fig. 5, 20 g of iron acetyl acetonate was dissolved in 1000 ml of ethyl alcohol to obtain a metal compound precursor solution (4). After making droplets of the metal precursor solution by the ultrasonic nebulizer 3, acetylene gas 2 was injected at a flow rate of 1 lpm, and nitrogen gas 1 as the carrier gas of the droplets was 50, 100, 150, 200, respectively. The mixture precursor 5 was transported through the internal nozzle of the burner by injection at a flow rate of 250 SCCM. At this time, in order to suppress the reaction of the mixed gas precursor and the carbonized gas such as outside air, nitrogen as a blocking gas was supplied at a flow rate of 2.5 lpm through an external nozzle of the burner. The flame containing the formed carbon particles was irradiated with a CO ₂ laser (8) having an intensity of 2.8 × 10 ⁴ W / cm ₂ to obtain a shell shape of an average particle diameter of 100 nm and iron of 122, 187, 224, 715, and 2162 ppm, respectively. Carbon particles 10 were prepared.

Example 2 Preparation of Platinum-doped Shell Shaped Carbon Particles

Platinum having a particle size of 100 nm in the same manner as in Example 1, except that 20 g of platinum acetyl acetonate was dissolved in 1000 ml of ethyl alcohol, and 150 SCCM of nitrogen gas (1) was used as a carrier gas. Doped shell-shaped carbon particles were prepared.

Example 3 Preparation of Manganese-Doped Shell Shaped Carbon Particles

Manganese having a particle size of 100 nm in the same manner as in Example 1, except that 20 g of manganese acetyl acetonate was dissolved in 1000 ml of ethyl alcohol, and 150 SCCM of nitrogen gas (1) was used as a carrier gas. Doped shell-shaped carbon particles were prepared.

Example 4 Preparation of Rubidium-Doped Shell Shaped Carbon Particles

Rubidium having a particle diameter of 100 nm in the same manner as in Example 1, except that 20 g of rubidium acetyl acetonate was dissolved in 1000 ml of ethyl alcohol, and 150 SCCM of nitrogen gas (1) was used as a carrier gas. Doped shell-shaped carbon particles were prepared.

Comparative Example 1 Preparation of Pure Shell Shaped Carbon Particles

Hydrogen was supplied at a flow rate of 1.0 lpm and oxygen / nitrogen mixers were mixed at a molar ratio of 1: 1 and fed at a flow rate of 1.0 lpm to form a hydrogen / oxygen diffusion flame. Acetylene gas was supplied thereto at a flow rate of 0.1 lpm or a mass flow rate of 7.0 g / hr to contact the flame to produce a soot precursor. At this time, a blocking gas nozzle was placed between the flame and acetylene to supply nitrogen, which is a blocking gas, at a flow rate of 0.35 lpm. The soot precursor was irradiated with a CO ₂ laser having an intensity of 2.2 × 10 4 W / cm ₂ to prepare pure shell-shaped carbon particles (see Korean Patent Publication No. 2002-66443).

Comparative Example 2 : Preparation of amorphous char

It was prepared in the same manner as in Example 2 except that nitrogen gas was supplied as 400 SSCM as a carrier gas.

Test Example 1 Structural and Physical Properties of Iron (Fe) -Doped Shell Carbon Particles

In order to examine the structural characteristics of the iron-doped shell-shaped carbon particles prepared in Example 1, a transmission electron microscope (Jeol, JEM-3000F) photograph is shown in Figure 6, the amount of iron doping (A) and Raman (Energy Dispersive X-ray Spectroscopy, Oxford, Inc.) comparing the shell-shaped carbon particles with those of the pure shell-shaped carbon particles doped with the metal of Comparative Example 1 Raman) spectroscopic analysis (Jobin Yvon, LabRamHR) results (b) are shown in FIG.

As can be seen in Figure 6, the carbon particles according to Example 1 was confirmed that the iron-doped structure of the shell-shaped carbon particles close to the hollow sphere of the plurality of layers connected to the planar and curved graphitized layer structure.

In addition, as can be seen from the XRD results of FIG. 7 (a), it was confirmed that diffraction peaks corresponding to the (002) and (101) planes of the well-crystallized graphite were clearly seen. The Raman analysis shows that the D peak associated with the amorphousness of the carbon bond remains unchanged, but the G peak associated with the crystallinity shows that the doping of the iron increases with increasing iron doping, indicating that iron is doped in the graphite crystal structure. there was.

Electron paramagnetic resonance (EPR, ESP-300S, Bruker, Inc.) and superconducting quantum interference device (MPMS) to investigate the magnetic properties of the iron-doped shell-shaped carbon particles prepared in Example 1 -7, Quantum Design) analysis results are shown in Figure 8, and compared with the conventional carbon nanotubes and Comparative Example 1, the field emission tester compared to the carbon particles of the metal-doped shell shape (field emission tester) ) Results are shown in FIG. 9.

As can be seen in Figure 8, the iron-doped shell-shaped carbon particles of Example 1 was confirmed that the iron ions are doped with a + trivalent between the carbon crystal structure. Typical carbon allotrope has diamagnetic properties of graphite and nanotubes, and non-magnetic properties of fullerene and diamond, whereas iron-doped shell carbon particles exhibit unique magnetic properties. In other words, the iron-doped shell-shaped carbon particles showed ferromagnetic and paramagnetic properties based on about 20 K depending on the temperature, and paramagnetism due to the distribution of doped iron ions according to the external magnetic field or interaction with carbon, which is a matrix structure. Its unique magnetic properties are a mixture of hard-ferromagnetism and soft-ferromagnetism. Such magnetic properties may be used for recording media, magnetic fluids, and biological fields that require the properties.

In the field electron emission test results of the iron-doped shell-shaped carbon particles shown in FIG. 9, the field electron emission threshold was 2 V / μm or less, which was lower than that of the aligned carbon nanotubes (CNTs), and the field electron emission current. The density was three times higher than that of the shell-shaped carbon particles (SCNPs) or carbon nanotubes which are not doped with the metal of Comparative Example 1, and have excellent long-term stability of electron emission, thus exhibiting excellent characteristics as a field electron emission device.

Test Example 2: Structural Characterization of Platinum (Pt) -Doped Shell Shaped Carbon Particles

In order to examine the structural characteristics of the platinum-doped shell-shaped carbon particles prepared in Example 2, transmission electron microscopy (TEM) images and EDS analysis (a) and X-ray diffraction analysis results (b) are shown in FIG. 10. Shown in

As can be seen from the TEM image and the EDS analysis result of FIG. 10 (a), it was confirmed that platinum was doped into the shell-shaped carbon particles, and as can be seen from the XRD results of FIG. 10 (b), graphite The peaks corresponding to the (002) and (101) planes were clearly seen, and it was confirmed that the crystallinity was excellent. Such platinum-doped shell-shaped carbon particles may be applied to fields such as catalysts and fuel cells.

Test Example 3 Structural and Physical Properties of Manganese (Mn) -doped Shell Carbon Particles

A transmission electron micrograph (a) and a magnetic property analysis result (b) of the manganese-doped shell-shaped carbon particles prepared in Example 3 are shown in FIG. 11.

As can be seen in Figure 11, it was confirmed that the manganese doped in the shell-shaped carbon particles, in order to analyze the magnetic properties of the manganese-doped carbon particles, by fixing the external magnetic field to 100G according to the temperature change Examining the ZFC (zero field cooling) and FC (field cooling) curves, it can be seen that it exhibits unique magnetic characteristics not seen in the existing manganese.

Test Example 3: Structural and physical property test of rubidium (Rb) -doped shell-shaped carbon particles

The transmission electron micrograph (a) and the magnetic property analysis result (b) of the manganese-doped shell-shaped carbon particles prepared in Example 4 are shown in FIG. 12.

As can be seen in Figure 12, it was confirmed that the rubidium is doped to the shell-shaped carbon particles, it is possible to confirm the possibility of the superconducting properties that can be seen when the alkali metal interacts with carbon by doping rubidium to the carbon particles. there was.

As described above, the metal-doped shell-shaped carbon particles according to the present invention exhibit new characteristics that are distinguished from the conventional carbon particles according to the type of metal to be doped or by interaction with carbon, which is a known structure, or have improved electrical and magnetic properties. Due to its properties, it can be usefully used in various fields such as magnetic recording media, biomaterials, field emission devices, nanofluids, and superconducting materials.

Claims (11)

Shell-shaped carbon particles composed of a plurality of layers connected with planar and curved graphitized layered structures and doped with metal to carbon particles with empty internal centers. The method of claim 1, Carbon particles, characterized in that the metal is a transition metal, a noble metal or an alkali metal or a combination thereof. The method of claim 1, Carbon particles, characterized in that the average particle diameter is 1 nm to 500 ㎛. a) supplying a hydrocarbon gas comprising a metal containing precursor material into the burner to ignite, b) irradiating a laser to the ignited flame Method of producing a shell-shaped carbon particles doped with a metal. The method of claim 4, wherein Metal-containing precursor materials include iron acetyl acetonate, iron penta carbonyl, manganese acetyl acetonate, manganese chloride, cobalt acetyl acetonate, platinum acetyl acetonate, platinum chloride, gold chloride, rubidium acetyl acetonate, potassium chloride and their Characterized in that it is selected from the mixtures. The method of claim 4, wherein the metal containing precursor material is supplied in the form of droplets or gases. The method of claim 4, wherein The hydrocarbon gas is acetylene gas, ethylene gas or methane gas. delete The method of claim 4, wherein In step (a), a blocking gas is introduced to suppress a chemical reaction between the mixed precursor of the metal-containing precursor material and the hydrocarbon gas and the outside air. The method of claim 9, And the blocking gas is nitrogen gas or argon gas. The method of claim 4, wherein Wherein the laser is a CO ₂ laser.

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