KR20200089573A - Manufacturing method of hollow hierarchical nanofibers by using carbon coating - Google Patents

Abstract

The present invention relates to a method for manufacturing hollow hierarchical nanofibers using carbon coating and, more specifically, to a method for manufacturing hollow hierarchical nanofibers using carbon coating, which has a hollow hierarchical structure to provide a high specific surface area and is coated with carbon to secure structural stability. According to one aspect of the present invention, a method for manufacturing hollow hierarchical nanofibers using carbon coating of a nanofiber-nanorod composite can secure structural stability through a step of being coated with carbon while forming a hollow hierarchical structure to provide a high specific surface area. According to another aspect of the present invention, through a step of coaxial electrospinning of a carbon material, a method for manufacturing hollow hierarchical nanofibers using carbon fiber coated with carbon can secure structural stability and simplify a process and can form a hollow hierarchical structure to increase a specific surface area. According to the present invention, the method comprises a nanofiber manufacturing step, a metal seed deposition step, a nanofiber-nanorod composite forming step, and a carbon coating step.

Description

Manufacturing method of hollow layered nanofibers using carbon coating {Manufacturing method of hollow hierarchical nanofibers by using carbon coating}

The present invention relates to a method for manufacturing a hollow layered nanofiber using a carbon coating, and more particularly, to form a hollow layered structure, having a high specific surface area, and coating with carbon to secure structural stability. It relates to a method of manufacturing nanofibers.

The transition metal is eco-friendly due to its high theoretical capacity and non-toxicity. However, the transition metal has a problem of showing a rapid change in volume and low ion conductivity during charging and discharging. In order to solve these problems, research is being conducted to increase the utilization through methods of alloying, coating, and synthesizing to nanostructures.

Recently, various types of metal oxides are manufactured in the form of nanostructures such as nanowires, nanorods, nanotubes, and nanoribbons. Is being made. The fundamental reason for this active research is that nano-sized materials are predicted to exhibit various physical and chemical properties different from bulk or thin-film materials compared to the existing bulk or thin-film materials. Or, it is because excellent physical properties are actually applied to various functional elements.

However, as a conventional metal oxide nanostructure manufacturing method, it is not easy to control the mold sol-gel method or the nanowire oxidation method to have a desired length and thickness uniformly due to limitations of the manufacturing method. In addition, even if a complex is formed as in Korean Patent Registration No. 10-1777975, the specific surface area of nanofibers may not be secured to the maximum, or structural instability may occur due to the use of metal oxides.

Therefore, in the manufacture of metal oxide nanostructures, there is a need for a technique capable of controlling the length and thickness of nanostructures, particularly nanofibers as a template, and further increasing the specific surface area. In addition, there is a problem in that durability must be secured by imparting stability to the nanostructure.

Republic of Korea Registered Patent No. 10-1777975

In order to solve the above problems, the present invention provides a method of manufacturing a hollow layered nanofiber to secure structural stability by carbon coating a nanofiber-nanorod composite while having a high specific surface area by forming a hollow layered structure. Providing them as technical solutions.

Another aspect of the present invention is to provide a method of manufacturing a hollow layered nanofiber having a high specific surface area and structural stability by forming a hollow layered structure using carbon coated nanofibers.

The present invention to solve the above technical problem,

A first step of producing a nanofiber by electrospinning a polymer solution;

A second step of heat-treating the nanofibers to form a hollow structure and depositing a metal seed;

A third step of forming a nanofiber-nanorod complex by growing nanorods by hydrothermal synthesis on the nanofibers on which the metal seeds are deposited; And

A fourth step of carbon coating the nanofiber-nanorod composite with a carbon material; It provides a method of manufacturing a hollow layered nanofibers comprising a.

The present invention to solve the above other technical problems,

A first step of preparing a nanofiber coated with carbon by coaxially spinning a polymer solution and a carbon material;

A second step of heat-treating the nanofibers to form a hollow structure and depositing a metal seed; And

A third step of forming a nanofiber-nanorod complex by growing nanorods by hydrothermal synthesis on the nanofibers on which the metal seeds are deposited; It provides a method of manufacturing a hollow layered nanofibers comprising a.

The heat treatment temperature of the second step may include 450 ~ 550 ℃.

The growth of the nanorods in the third step may form a barbed structure.

According to the present invention, a method of manufacturing a hollow layered nanofiber with a carbon fiber coating a nanofiber-nanorod composite may form a hollow layered structure to secure structural stability through a carbon coating step having a high specific surface area.

Hollow layer structure using carbon-coated nanofibers according to the present invention The method for manufacturing nanofibers secures structural stability and simplifies the process through the step of co-electrospinning a carbon material, and forms a hollow layer structure to form a specific surface area. Can increase.

1 is a schematic diagram showing a manufacturing method implemented in an embodiment of the present invention.
Figure 2 is a cross-sectional view in the longitudinal direction and the radial direction of the nanofibers implemented in an embodiment of the present invention.
Figure 3 is a schematic diagram showing a manufacturing method implemented in another embodiment of the present invention.
Figure 4 is a cross-sectional view of the longitudinal and radial direction of the nanofibers implemented in another embodiment of the present invention.
5 is an SEM image of nanofibers in the coaxial electrospinning step of another embodiment of the present invention.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings.

According to an aspect of the present invention, a first step of producing a nanofiber by electrospinning a polymer solution; A second step of heat-treating the nanofibers to form a hollow structure and depositing a metal seed; A third step of forming a nanofiber-nanorod complex by growing nanorods by hydrothermal synthesis on the nanofibers on which the metal seeds are deposited; And a fourth step of carbon coating the nanofiber-nanorod composite with a carbon material; It provides a method of manufacturing a hollow layered nanofibers comprising a.

1 is a schematic diagram showing a manufacturing method implemented in an embodiment of the present invention. Referring to Fig. 1, each step will be described below.

First, a first step of producing nanofibers by electrospinning will be described.

The electrospinning process is a process for producing nanofibers having a diameter in the range of μm to nm by generating an electric field between a charged precursor solution and an electrode plate, and is used for all polymer materials that can be mixed and melted with a solvent. There are no restrictions, and it can be used relatively simply compared to the process of manufacturing other one-dimensional nanostructures such as self-assembly, phase separation, and mold formation.

Electrospinning, electrospraying, and melt electrospinning may be used in the electrospinning process, but is not limited thereto.

For the synthesis of nanofibers using electrospinning, a solution containing a nanofiber precursor having a metal seed, a water-soluble polymer capable of crosslinking by applying heat, and a bipolar liquid serving as a solvent may be prepared.

Nanofiber precursors that can be used as metal seeds to form metal oxides are zinc (Zn), tin (Sn), titanium (Ti), nitride, chloride, sulfide, and acetate , Acetylacetonate, cyanide, isopropyl oxide, butoxide. Preferably, it may be at least one selected from zinc, tin, and titanium, and more preferably, zinc may be used.

Water-soluble polymers capable of crosslinking include polyvinyl alcohol (PVA), polyacrylic acid (PAA), polystyrene sulfonic acid (PSSA), polyhydroxyethyl methacrylate, Polyethylene oxide (PEO), polyvinyl pyrrolidone (PVP), polyacrylamide (PA), polymethyl methacrylate (PMMA), polymethylacrylate (PMA) ), polyvinyl acetate (PVAc), polyvinyl chloride (PVC), polypropylene oxide (PPO), polyacrylonitrile (PAN), polylactic acid (polylactic acid: PLA) L-polylactide (poly L-lactic acid: PLLA), D-polylactide (poly D-lactic acid: PLLA). Preferably, it can be any one of polyvinyl pyrrolidone (PVP), polyacrylamide (PA), polymethyl methacrylate (PMMA), and polymethylacrylate (PMA). And more preferably, polyvinyl pyrrolidone (PVP) can be used.

The bipolar liquid, which can act as a solvent, must be able to completely dissolve the water-soluble polymer. Ethanol, methanol, ethyl acetate, methylene chloride, dimethylfornamide (DMF), tetrahydrofuran (THF), methyl ethyl ketone ), 1,2-dichloroethane, 1,2-propanol, n-butanol, or acetone. Preferably, at least one selected from the group consisting of ethanol, methanol, ethyl acetate, and dimethylformamide (DMF) may be used, more preferably dimethylformamide (Dimethylfornamide: DMF) can be used.

On the other hand, it is possible to control the electrospinning conditions by adjusting the proportion of the solvent. Since the boiling point, concentration, and surface tension of the solution change depending on the ratio of the solvent, the thickness, length, and shape of the prepared nanofibers can be adjusted.

Next, a second step of forming a hollow structure and depositing a metal seed by heat treatment of the nanofibers will be described.

First, the nanofibers produced by electrospinning can be thermoset to make the polymer crosslink. The cross-linked polymer may form a nanofiber shape and include a nanofiber precursor having a metal seed therein. Heat curing can be performed by heat treatment at 100~150℃. It is preferable that a heat treatment time of 5 minutes to 1 hour is allowed to sufficiently complete crosslinking.

Thereafter, a hollow nanofiber having pores may be formed through heat treatment. A hollow structure may be formed by removing the polymer contained in the nanofibers. The heat treatment is preferably performed in an oxidizing atmosphere, but is not limited thereto.

Furthermore, a metal oxide nanofiber can be formed by substituting the hydrogen bond portion of a metal atom in a crosslinked polymer with oxygen through a heat treatment process. In order to form a hierarchical structure, a metal seed may be deposited through dip coating, drying, and heat treatment of a metal oxide precursor solution.

It is preferable that the heat treatment temperature includes 50 to 550°C. More preferably it may include 450 ~ 550 ℃. In the case of less than 450°C, hydrogen cannot be replaced with oxygen, so metal oxide may not be formed, which is not preferable. If it exceeds 550°C, it is not preferable because the metal oxide protrusions are formed on the nanofibers or the nanofiber structure collapses and crystallinity may decrease. The diameter of the nanofibers may decrease as the temperature increases and the heat treatment time increases.

It is preferable that the heat treatment time includes 2 to 4 hours. If the heat treatment time is long, the thickness of the metal oxide is continuously reduced, and thus the structure of the nanofibers may disappear, and if it is too short, the temperature may decrease before forming the metal oxide due to insufficient heat.

Next, a third step of forming a nanofiber-nanorod composite by growing nanorods by hydrothermal synthesis on nanofibers on which metal seeds are deposited will be described.

Hexamethyltetradiamine (HMTA: (CH2) ₆ N ₄ ) of 0.01M ~ 0.1M, Zinc Nitrate hexahydrate: Zn(NO ₃ ) ₂ of 0.01M ~ 0.1M on the hollow nanofiber formed by heat treatment 6H ₂ O) Nanorods can be grown through hydrothermal reaction of aqueous solutions.

Zinc nitrate hexahydrate is nitride, chloride, sulfide, acetate, acetylacetonate, cyanide, isopropyl oxide, butoxide It may be at least one selected from the group consisting of). Preferably, nitride can be used.

The diameter of the nanorods may vary from 200 nm to 1 um depending on the ratio of hexamethyltetradiamine and zinc nitrate hexahydrate. The larger the proportion of zinc nitrate hexahydrate, the larger the diameter of the nanorods.

Nanorods grown by hydrothermal synthesis may form a barbed structure. The barbed structure may have a sharp or pointed shape with a visible shape. It may include a structure formed at regular lengths or intervals. A structure having a large specific surface area can be formed by forming a barbed structure.

Finally, a fourth step of carbon coating the nanofiber-nanorod composite with a carbon material will be described.

The nanofiber-nanorod composite on which the nanorod is grown may be coated with a carbon material. The carbon material may include molecules, compounds, and the like, including carbon. The nanofiber-nanorod composite can be put in an aqueous carbon material solution to coat the composite with carbon. The thickness of the carbon coating layer can be adjusted according to the proportion of the carbon material in the aqueous carbon material solution. Furthermore, the crystallinity can be improved through heat treatment.

The nanofiber manufacturing method of the present invention is characterized by forming a hollow layered structure and including a carbon coating step. Figure 2 is a cross-sectional view in the longitudinal direction and the radial direction of the nanofibers implemented in an embodiment of the present invention. Referring to FIG. 2, the nanofiber manufacturing method of the present invention forms a hollow hierarchical structure, and thus has a wide surface area and excellent structural efficiency. In addition, since it includes a carbon coating step, it is possible to stably secure the conductivity of the metal oxide, and thus, it can be expected to utilize the secondary battery as a negative electrode material. In addition, since it is manufactured by a known process, it is possible to mass-produce the anode material, and it is also possible to consider expansion of the utilization range.

According to another aspect of the present invention, a first step of preparing a carbon fiber-coated nanofiber by coaxially spinning a polymer solution and a carbon material; A second step of heat-treating the nanofibers to form a hollow structure and depositing a metal seed; And a third step of growing nanorods by hydrothermal synthesis on the nanofibers on which the metal seeds are deposited; It provides a method of manufacturing a hollow layered nanofibers comprising a.

Figure 3 is a schematic diagram showing a manufacturing method implemented in another embodiment of the present invention. Each step will be described below with reference to FIG. 3.

The first step of producing a nanofiber coated with carbon by coaxially spinning a polymer solution and a carbon material will be described.

Coaxial electrospinning can produce nanofibers having a coaxial double layer structure using an inner nozzle and an outer nozzle. The carbon material of the outer nozzle is spun into a hollow cylinder shape, and the polymer solution of the inner nozzle is discharged while being filled inside the carbon material, and can be made of nanofibers having a coaxial double layer structure while being discharged. The carbon material may include molecules, compounds, and the like, including carbon. The carbon material and the polymer solution do not mix with each other. The spinning speed of the carbon material in the outer nozzle is preferably the same or greater than the spinning speed of the polymer solution in the inner nozzle. Further, it is preferable that the viscosity of the carbon material is equal to or greater than that of the internal polymer solution.

Since nanofibers are manufactured using a coaxial electrospinning method, structural stability can be secured without a separate coating process, thereby simplifying the manufacturing process and reducing costs.

Electrospinning, electrospraying, and melt electrospinning may be used in the electrospinning process, but is not limited thereto.

For the synthesis of nanofibers using electrospinning, a solution containing a nanofiber precursor having a metal seed, a water-soluble polymer capable of crosslinking by applying heat, and a bipolar liquid serving as a solvent may be prepared.

Nanofiber precursors that can be used as metal seeds to form metal oxides include zinc (Zn), tin (Sn), titanium (Ti), nitride, chloride, sulfide, and acetate. , Acetylacetonate, cyanide, isopropyl oxide, butoxide. Preferably, it may be at least one selected from zinc, tin, and titanium, and more preferably, zinc may be used.

Water-soluble polymers capable of crosslinking include polyvinyl alcohol (PVA), polyacrylic acid (PAA), polystyrene sulfonic acid (PSSA), polyhydroxyethyl methacrylate, Polyethylene oxide (PEO), polyvinyl pyrrolidone (PVP), polyacrylamide (PA), polymethyl methacrylate (PMMA), polymethylacrylate (PMA) ), polyvinyl acetate (PVAc), polyvinyl chloride (PVC), polypropylene oxide (PPO), polyacrylonitrile (PAN), polylactic acid (polylactic acid: PLA) L-polylactide (poly L-lactic acid: PLLA), D-polylactide (poly D-lactic acid: PLLA). Preferably, it can be any one of polyvinyl pyrrolidone (PVP), polyacrylamide (PA), polymethyl methacrylate (PMMA), and polymethylacrylate (PMA). And more preferably, polyvinyl pyrrolidone (PVP) can be used.

The bipolar liquid, which can act as a solvent, must be able to completely dissolve the water-soluble polymer. Ethanol, methanol, ethyl acetate, methylene chloride, dimethylfornamide (DMF), tetrahydrofuran (THF), methyl ethyl ketone ), 1,2-dichloroethane, 1,2-propanol, n-butanol, or acetone. Preferably, at least one selected from the group consisting of ethanol, methanol, ethyl acetate, and dimethylformamide (DMF) may be used, more preferably dimethylformamide (Dimethylfornamide: DMF) can be used.

On the other hand, it is possible to control the electrospinning conditions by adjusting the proportion of the solvent. Since the boiling point, concentration, and surface tension of the solution change depending on the ratio of the solvent, the thickness, length, and shape of the prepared nanofibers can be adjusted.

Next, a second step of forming a hollow structure and depositing a metal seed by heat treatment of the nanofibers will be described.

First, the nanofibers produced by electrospinning can be thermoset to make the polymer crosslink. The cross-linked polymer may form a nanofiber shape and include a nanofiber precursor having a metal seed therein. Heat curing can be performed by heat treatment at 100~150℃. It is preferable that a heat treatment time of 5 minutes to 1 hour is allowed to sufficiently complete crosslinking.

Thereafter, a hollow nanofiber having pores may be formed through heat treatment. A hollow structure may be formed by removing the polymer contained in the nanofibers. The heat treatment is preferably performed in an oxidizing atmosphere, but is not limited thereto.

Furthermore, a metal oxide nanofiber can be formed by substituting the hydrogen bond portion of a metal atom in a crosslinked polymer with oxygen through a heat treatment process. To form a hierarchical structure, a metal seed may be deposited through dip coating, drying, and heat treatment of the metal oxide precursor solution.

It is preferable that the heat treatment temperature includes 50 to 550°C. More preferably it may include 450 ~ 550 ℃. In the case of less than 450°C, hydrogen cannot be replaced with oxygen, so metal oxide may not be formed, which is not preferable. If it exceeds 550°C, it is not preferable because the metal oxide protrusions are formed on the nanofibers or the nanofiber structure collapses and crystallinity may decrease. The diameter of the nanofibers may decrease as the temperature increases and the heat treatment time increases.

It is preferable that the heat treatment time includes 2 to 4 hours. If the heat treatment time is long, the thickness of the metal oxide is continuously reduced, and thus the structure of the nanofibers may disappear, and if it is too short, the temperature may decrease before forming the metal oxide due to insufficient heat.

Next, a third step of forming a nanofiber-nanorod composite by growing nanorods by hydrothermal synthesis on the nanofibers on which the metal seeds are deposited will be described.

Hexamethyltetradiamine (HMTA: (CH2) ₆ N ₄ ) of 0.01M ~ 0.1M, Zinc Nitrate hexahydrate: Zn(NO ₃ ) ₂ of 0.01M ~ 0.1M on the hollow nanofiber formed by heat treatment 6H ₂ O) Nanorods can be grown through hydrothermal reaction of aqueous solutions.

Zinc nitrate hexahydrate is nitride, chloride, sulfide, acetate, acetylacetonate, cyanide, isopropyl oxide, butoxide It may be at least one selected from the group consisting of). Preferably, nitride can be used.

The diameter of the nanorods may vary from 200 nm to 1 um depending on the ratio of hexamethyltetradiamine and zinc nitrate hexahydrate. The larger the proportion of zinc nitrate hexahydrate, the larger the diameter of the nanorods.

Nanorods grown by hydrothermal synthesis may form a barbed structure. The barbed structure may have a sharp or pointed shape with a visible shape. It may include a structure formed at regular lengths or intervals. A structure having a large surface area can be formed by forming a barbed structure.

The method for manufacturing nanofibers according to another aspect of the present invention is characterized by forming a hollow hierarchical structure based on nanofibers coated with carbon by coaxially spinning a carbon material. Figure 4 is a cross-sectional view of the longitudinal and radial direction of the nanofibers implemented in another embodiment of the present invention. Referring to FIG. 4, the method for manufacturing nanofibers according to another aspect of the present invention forms a hollow hierarchical structure, and thus has a wide surface area and excellent structural efficiency. By manufacturing the nanofiber coated with carbon, it is possible to maintain the conductivity of the metal oxide while securing structural stability, and thus, it can be expected to be used as a negative electrode material of the secondary battery. In addition, since it can be manufactured without a separate coating step, mass production is possible through simplification of the process, and expansion of the utilization range can be considered.

The present invention will be described in more detail by the following examples. However, the following examples are intended to illustrate the present invention and the scope of the present invention is not limited by the examples. The present disclosure is made to be complete, and is provided to completely inform the scope of the invention to those skilled in the art.

<Example>

Example 1-Method for preparing nanofiber-nanorod composite by carbon coating

(1) Electrospinning stage

Zinc nitrate (Zn(NO ₃ ) ₂ ) is used as a nanofiber precursor and polyvinyl pyrrolidone (PVP) is used as a water-soluble polymer, and ethanol and dimethylformamide are used as bipolar solvents. (Dimethylfornamide: DMF) was used. A solution was prepared using 8.9 wt% of zinc nitrate hexahydrate, 22.2 wt% of polyvinyl pyrrolidone, 15.6 wt% of ethanol, and 53.4 wt% of dimethylformamide. In the electrospinning step, the solution rate of the syringe pump was set to 1 ml/h, the voltage was 15 kV, and the distance between the syringe tip and the collection surface was 15 cm. The spinning needle used a size of 27 Ga.

(2) Heat treatment step

ZnO nanofibers were formed by heat treatment at 500° C. in a box electric furnace for 3 hours.

(3) Hydrothermal synthesis step

In the hydrothermal synthesis step of growing the nanorods, the mixture was stirred at 500 rpm for 1 hour, hydrothermal synthesized at 120°C for 10 hours, rinsed with distilled water and ethanol, and dried at 80°C for 12 hours. Through hydrothermal reaction in an aqueous solution of 0.01 M hexamethyltetradiamine (HMTA) (CH ₂ ) ₆ N ₄ ), 0.01 M zinc nitrate hexa hydrate (Zn(NO ₃ ) ₂ · 6H ₂ O) Nanorods were grown on hollow nanofibers.

(4) Carbon coating step

The nanofiber-nanorod composite was added to an aqueous solution of 0.03M α-D-glucose and carbon was coated. As a result, a hollow layered nanofiber prepared by carbon coating the nanofiber-nanorod composite was obtained.

Example 2-Method for producing nanofiber by carbon coating

(1) Coaxial electrospinning stage

Zinc nitrate hexahydrate was used as a nanofiber precursor for the inner nozzle and polyvinyl pyrrolidone was used as a water-soluble polymer, and 0.03M α-D-glucose was used as the carbon material for the outer nozzle. Ethanol and dimethylformamide were used as the bipolar solvent. A solution was prepared using 8.9 wt% of zinc nitrate hexahydrate, 22.2 wt% of polyvinyl pyrrolidone, 15.6 wt% of ethanol, and 53.4 wt% of dimethylformamide. In the electrospinning step, the solution rate of the syringe pump was set to 1 ml/h, the voltage was 15 kV, and the distance between the syringe tip and the collection surface was 15 cm. The spinning needle used a size of 27 Ga. 5 is an SEM image of nanofibers in the coaxial electrospinning step of Example 2.

(2) Heat treatment step

ZnO nanofibers were formed by heat treatment at 500° C. in a box electric furnace for 3 hours.

(3) Hydrothermal synthesis step

In the hydrothermal synthesis step of growing the nanorods, the mixture was stirred at 500 rpm for 1 hour, hydrothermal synthesized at 120°C for 10 hours, rinsed with distilled water and ethanol, and dried at 80°C for 12 hours. Nano on nanofibers through hydrothermal reaction in an aqueous solution of 0.01 M hexamethyltetradiamine (HMTA) (CH ₂ ) ₆ N ₄ ), 0.01 M zinc nitrate hexahydrate (Zn(NO ₃ ) ₂ · 6H ₂ O) The rod was grown. As a result, a hollow layered nanofiber prepared by carbon coating the nanofiber was obtained.

<Evaluation and Results>

(1) Specific surface area

The specific surface area refers to the surface area (area of the solid surface) per volume of particles. Therefore, the smaller the particle diameter, the larger the surface area in structure, the larger the specific surface area. If the specific surface area is large, efficiency can be increased in a field that utilizes a three-dimensional structure. An embodiment of the present invention forms a hollow nanofiber. The hollow shape has a higher specific surface area because the area of friction with the external environment is wider than that of the hollow shape. Furthermore, it can be confirmed that it is an easy structure to secure the efficiency of the structure because the specific surface area is further increased by forming a hierarchical barbed structure. When the structure manufactured by the manufacturing method of the present invention is used as a negative electrode material for a lithium secondary battery, a high capacity may be secured based on a high specific surface area.

(2) structural stability

When the stability of the manufactured structure is secured, durability can be increased in a field utilizing the structure and have a high lifespan effect. Since the nano-sized material may be easily oxidized by oxygen or have a lower melting point, it may be combined with a step of coating the surface to maintain the characteristics or exhibit better characteristics even in a nano-sized state. In the embodiment of the present invention, structural stability was secured by carbon coating a nanofiber-nanorod composite or nanofiber. Carbon coatings have been applied in numerous fields because of their high modulus of elasticity, high hardness and wear resistance. When using the structure manufactured by the manufacturing method of the present invention, it will be possible to secure a high life based on the structural stability according to the carbon coating.

The hollow layered nanofiber manufacturing method of carbon coating the nanofiber-nanorod composite according to the present invention can secure the structural stability through the step of carbon coating while forming a hollow layered structure with a high specific surface area, Hollow hierarchical structure using carbon-coated nanofibers The nanofiber manufacturing method secures structural stability and simplifies the process through the step of co-electrospinning a carbon material, and increases the specific surface area by forming a hollow hierarchical structure. Is excellent in

In addition, the effect of specific surface area and structural stability can be controlled by modifying the shape of nanofibers prepared according to the experimental conditions at each step of the manufacturing method. In the electrospinning step, the thickness and length of the nanofibers are adjusted according to the ratio of the solvent, in the heat treatment step, the diameter of the nanofibers is adjusted according to the heat treatment temperature and time, and in the hydrothermal synthesis step, the ratio of hexamethyltetradiamine and zinc nitrate Depending on the diameter of the growing nanorods can be adjusted. In addition, the thickness of the carbon coating layer can be adjusted according to the proportion of the carbon material in the aqueous carbon material solution. It is excellent in that the structure can be modified by adjusting the conditions for each process step in the existing process depending on the field in which the manufactured structure is used.

Claims (4)

A first step of producing a nanofiber by electrospinning a polymer solution;
A second step of heat-treating the nanofibers to form a hollow structure and depositing a metal seed;
A third step of forming a nanofiber-nanorod complex by growing nanorods by hydrothermal synthesis on the nanofibers on which the metal seeds are deposited; And
A fourth step of carbon coating the nanofiber-nanorod composite with a carbon material; Method for producing a hollow layered nanofibers comprising a. A first step of preparing a nanofiber coated with carbon by coaxially spinning a polymer solution and a carbon material;
A second step of heat-treating the nanofibers to form a hollow structure and depositing a metal seed; And
A third step of forming a nanofiber-nanorod complex by growing nanorods by hydrothermal synthesis on the nanofibers on which the metal seeds are deposited; Method for producing a hollow layered nanofibers comprising a. The method according to claim 1 or 2, wherein the heat treatment temperature in the second step is 450 to 550°C. The method according to claim 1 or 2, wherein the growth of the nanorods in the third step forms a barbed structure.

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