Method for preparing surface-active onion-like carbon nanospheres based on vapor deposition

Abstract

The present invention discloses a method for preparing surface-active onion-like carbon nanospheres based on vapor deposition, comprising: directly preparing high-surface-activity onion-like carbon nanospheres formed by coating ferroferric oxide nano-particles on an onion-like graphitized shell by taking liquid small organic molecule alkane n-dodecane as a carbon source to perform chemical vapor deposition at high temperature of 650˜700° C. in an inert carrier gas environment with existence of a ferrocene catalyst. An onion-like carbon nanosphere product prepared according to the present invention has good surface activity and thermal stability, is wide in practicability, and can be widely applied to the fields of adsorbing materials, energy storage materials, catalytic materials, medical materials and the like.

Claims

1. A method for preparing surface-active onion-like carbon nanospheres based on vapor deposition, comprising: directly preparing high-surface-activity onion-like carbon nanospheres formed by coating ferroferric oxide nano-particles on an onion-like graphitized shell by taking liquid small organic molecule alkane n-dodecane as a carbon source to perform chemical vapor deposition at high temperature of 650˜700° C. in an inert carrier gas environment with existence of a ferrocene catalyst.

2. The method according to claim 1, wherein the use amount of the catalyst ferrocene is 0.050˜0.055 time of the mass of the carbon source n-dodecane.

3. The method according to claim 1, wherein the carbon source and the catalyst are added into water to prepare an aqueous dispersion.

4. The method according to claim 3, wherein the use amount of the water is 2˜3 times of the volume of the carbon source.

5. The method according to claim 1, wherein the chemical vapor deposition reaction time is 15˜20 min.

6. The method according to claim 1, wherein the inert carrier gas flow in the chemical vapor deposition reaction process is 5+/−1 mL/min.

7. The method according to claim 6, wherein the inert carrier gas flow is controlled to be not greater than 3 mL/min in a temperature rise period, and after temperature rises to a reaction temperature, adjusting the inert carrier gas flow to 5+/−1 mL/min.

8. Surface-active onion-like carbon nanospheres prepared by the method according to claim 1, wherein an Fe.sub.3O.sub.4 nanocrystalline metal kernel is coated inside the carbon nanosphere, and an outer layer being of an onion-like graphitized shell structure, with average particle size of 30 nm.

9. Surface-active onion-like carbon nanospheres prepared by the method according to claim 2, wherein an Fe.sub.3O.sub.4 nanocrystalline metal kernel is coated inside the carbon nanosphere, and an outer layer being of an onion-like graphitized shell structure, with average particle size of 30 nm.

10. Surface-active onion-like carbon nanospheres prepared by the method according to claim 3, wherein an Fe.sub.3O.sub.4 nanocrystalline metal kernel is coated inside the carbon nanosphere, and an outer layer being of an onion-like graphitized shell structure, with average particle size of 30 nm.

11. Surface-active onion-like carbon nanospheres prepared by the method according to claim 4, wherein an Fe.sub.3O.sub.4 nanocrystalline metal kernel is coated inside the carbon nanosphere, and an outer layer being of an onion-like graphitized shell structure, with average particle size of 30 nm.

12. Surface-active onion-like carbon nanospheres prepared by the method according to claim 5, wherein an Fe.sub.3O.sub.4 nanocrystalline metal kernel is coated inside the carbon nanosphere, and an outer layer being of an onion-like graphitized shell structure, with average particle size of 30 nm.

13. Surface-active onion-like carbon nanospheres prepared by the method according to claim 6, wherein an Fe.sub.3O.sub.4 nanocrystalline metal kernel is coated inside the carbon nanosphere, and an outer layer being of an onion-like graphitized shell structure, with average particle size of 30 nm.

14. Surface-active onion-like carbon nanospheres prepared by the method according to claim 7, wherein an Fe.sub.3O.sub.4 nanocrystalline metal kernel is coated inside the carbon nanosphere, and an outer layer being of an onion-like graphitized shell structure, with average particle size of 30 nm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a field emission scanning electron microscope morphological image of surface-active onion-like carbon nanospheres prepared according to the present invention.

(2) FIG. 2 shows transmission electron microscope morphological images of surface-active onion-like carbon nanospheres prepared according to the present invention.

(3) FIG. 3 is an X-ray diffraction intensity diagram of surface-active onion-like carbon nanospheres prepared according to the present invention.

(4) FIG. 4 is an infrared spectrogram of surface-active onion-like carbon nanospheres prepared according to the present invention.

(5) FIG. 5 is a thermal weight loss curve graph of surface-active onion-like carbon nanospheres prepared according to the present invention.

(6) FIG. 6 is a field emission scanning electron microscope morphological image of a product prepared in a comparative example 1.

(7) FIG. 7 is a transmission electron microscope morphological image of a product prepared in a comparative example 2.

DESCRIPTION OF THE EMBODIMENTS

(8) The following embodiments are merely preferred technical schemes of the present invention, and are not used for limiting the present invention in any form. A person skilled in the art may make various changes and variations. Any modification, equivalent replacement or improvements made within the spirit and principle of the present invention should fall within the protection scope of the present invention.

Embodiment 1

(9) Taking 2.5 mL (1.9 g) of n-dodecane and weighing 0.1 g of ferrocene, putting into 5 mL of deionized water together to perform ultrasonic mixing uniformly, and then putting the mixture into a quartz boat. Putting the quartz boat in the middle of a horizontal resistance furnace tube, and placing a glass slide at the tail portion in the furnace tube for products collection.

(10) Adjusting carrier gas flow to 30 mL/min by taking argon as a carrier gas to exhaust air in the furnace tube and start to heat; when temperature is risen to 100° C. at a temperature rise rate of 10° C./min, adjusting carrier gas flow down to 3 mL/min; continuing to rise temperature to 700° C. at a same temperature rise rate, adjusting carrier gas flow to 5 mL/min, and reacting for 20 min, so that vaporized n-dodecane performs sufficient carbonation reaction in a high temperature reaction zone to deposit on the glass slide prearranged in the furnace tube.

(11) After reaction is ended, adjusting carrier gas flow to 10 mL/min, naturally cooling to room temperature and then taking out the glass slide, and scraping to collect a black sediment on the glass slide, to obtain the pure surface-active onion-like carbon nanospheres.

(12) FIG. 1 shows a field emission scanning electron microscope morphological image of prepared surface-active onion-like carbon nanospheres. It may be seen that the surface-active onion-like carbon nanospheres present spherical or spheroid shapes, and are uniform in morphology, and narrow in particle size distribution scope, with average particle size of about 30 nm.

(13) FIG. 2 shows transmission electron microscope morphological images of the surface-active onion-like carbon nanospheres, wherein a) is a transmission electron microscope image of a single onion-like carbon nanosphere, and b) is a local amplified image of carbon layers of a). It is known from FIG. 2 that the onion-like carbon nanospheres are metal-encapsulating nano carbon spheres of about 30 nm, the size of an internal metal kernel is about 20 nm, the thickness of an external encapsulating carbon layer is about 5 nm, and it may be further observed from b) that a dozen of onion-like graphitized shells with equal distance exist on the carbon layer, and the measurement distance is about 0.342 nm, which is close to the layer distance of 0.336 of graphite, indicating that the graphitization degree of the product is better.

(14) FIG. 3 is an X-ray diffraction intensity diagram of surface-active onion-like carbon nanospheres. In FIG. 3, a relatively wide diffraction peak exists in a scope from 10° to 30°, and a strongest peak exists near 26.2°, indicating forming of a graphite layer corresponding to a carbon (002) crystal plane. Relatively strong diffraction peaks appear at 30.2°, 35.3°, 43.2°, 53.5°, 57.1° and 62.9°, which respectively belong to (220), (311), (400), (422), (511), (440) crystal planes of Fe.sub.3O.sub.4. Moreover, characteristic peaks of Fe.sub.3C exist at 45° and 65°, and characteristic peaks of Fe appear between 35° and 50°, indicating that carbon may generate a carbon thermal reduction reaction with Fe.sub.3O.sub.4 in a high temperature condition, and carbon can reduce Fe.sub.3O.sub.4 to be zero-valent ferrum. Meanwhile, zero-valent ferrum also plays a certain promoting role on the graphitization degree of carbon at high temperature.

(15) FIG. 4 is an infrared spectrogram of surface-active onion-like carbon nanospheres. Absorption peaks at 3435, 1631 and 1098 cm.sup.−1 respectively indicate the existence of oxygen-containing functional groups —OH, C═O and C—O, indicating that the surfaces of onion-like carbon nanospheres prepared by taking n-dodecane as a carbon source have a certain quantity of active oxygen-containing functional groups.

(16) FIG. 5 is a thermal weight loss curve graph of surface-active onion-like carbon nanospheres measured in a nitrogen atmosphere. It is shown in FIG. 5 that along with temperature rise, 12% of weight loss of the product before 150° C. mainly comes from removal of moisture in a sample. Subsequently, there is hardly any weight loss in a temperature scope from 150° C. to 600° C., indicating that the onion-like carbon nanospheres have better thermal stability. Along with further rise of temperature, when reaching 900° C., the total weight loss of the onion-like carbon nanospheres is about 55%, that is because a carbon layer is damaged along with continuous increase of temperature, further carbonization of a carbon layer on the outer layer of a material, loss of surface-active functional groups, generation of a carbon ion compound and catalytic action of Fe, therefore, the mass of surface-active onion-like carbon nanospheres is rapidly reduced after high temperature thermal treatment of over 800° C.

Embodiment 2

(17) Taking 1.5 mL (1.1 g) of n-dodecane and weighing 0.1 g of ferrocene, putting into 5 mL of deionized water together to perform ultrasonic mixing uniformly, and then putting the mixture into a quartz boat. Putting the quartz boat in the middle of a horizontal resistance furnace tube, and placing a glass slide at the tail portion in the furnace tube for products collection.

(18) Performing carbonation reaction according to conditions of embodiment 1, to prepare surface-active onion-like carbon nanospheres with particle size of about 30 nm.

Embodiment 3

(19) Taking 2.5 mL (1.9 g) of n-dodecane and weighing 0.1 g of ferrocene, putting into 10 mL of deionized water together to perform ultrasonic mixing uniformly, and then putting the mixture into a quartz boat. Putting the quartz boat in the middle of a horizontal resistance furnace tube, and placing a glass slide at the tail portion in the furnace tube for products collection.

(20) Performing carbonation reaction according to conditions of embodiment 1, to prepare surface-active onion-like carbon nanospheres with particle size of about 30 nm.

Comparative Example 1

(21) Taking 3.5 mL (2.6 g) of n-dodecane and weighing 0.1 g of ferrocene, putting into 5 mL of deionized water together to perform ultrasonic mixing uniformly, and then putting the mixture into a quartz boat. Putting the quartz boat in the middle of a horizontal resistance furnace tube, and placing a glass slide at the tail portion in the furnace tube for products collection, and performing carbonation reaction according to conditions of embodiment 1.

(22) FIG. 6 shows a field emission scanning electron microscope morphological image of a prepared product. It may be seen from FIG. 6 that when the amount of the carbon source n-dodecane is too high, the corresponding product carbon spheres are seriously agglomerated, as a result, granular spherical products cannot be obtained.

Comparative Example 2

(23) Taking 2.5 mL (1.9 g) of n-dodecane and weighing 0.1 g of ferrocene, putting into 5 mL of deionized water together to perform ultrasonic mixing uniformly, and then putting the mixture into a quartz boat. Putting the quartz boat in the middle of a horizontal resistance furnace tube, and placing a glass slide at the tail portion in the furnace tube for products collection.

(24) Adjusting carrier gas flow to 30 mL/min by taking argon as a carrier gas to exhaust air in the furnace tube and start to heat; when temperature is risen to 100° C. at a temperature rise rate of 10° C./min, adjusting carrier gas flow down to 3 mL/min; continuing to rise temperature to 600° C. at a same temperature rise rate, adjusting carrier gas flow to 5 mL/min, and reacting for 20 min, so that vaporized n-dodecane performs sufficient carbonation reaction in a high temperature reaction zone to deposit on the glass slide prearranged in the furnace tube.

(25) After reaction is ended, adjusting carrier gas flow to 10 mL/min, naturally cooling to room temperature and then taking out the glass slide, and scraping to collect a black sediment on the glass slide.

(26) It may be seen from a transmission electron microscope morphological image of a prepared product shown in FIG. 7 that when carbonization temperature is lowered, the carbon source fails to be effectively carbonized and adhered to the catalyst Fe.sub.3O.sub.4 metal particles, as a result, carbon nanosphere products with an onion-like structure are not obtained.

Comparative Example 3

(27) Other conditions are all the same as those in embodiment 1, and the difference only lies in that reaction is only performed for 10 min after temperature rises to 700° C., and then an obtained produced is collected.

(28) Because reaction time is too short, the carbon source fails to be effectively carbonized and adhered to the catalyst Fe.sub.3O.sub.4 metal particles, the transmission electron microscope image of the corresponding product is similar to that in FIG. 7, only Fe.sub.3O.sub.4 metal particles are obtained, and carbon nanosphere products of an onion-like structure are not obtained.

Comparative Example 4

(29) Other conditions are all the same as those in embodiment 1, and the difference only lies in that reaction is extended to 30 min after temperature rises to 700° C., and then an obtained product is collected.

(30) Due to reaction time extension and carrier gas purging, under the action of surface tension and diffusion force, catalyst particles are held up, to push a thermal carbon layer to grow along a length direction, meanwhile, pyrolytic carbon settles continuously, so as to finally obtain multi-walled carbon nanotubes.