KR101946446B1 - Method of Preparing Porous Carbon Materials Co-Doped with Boron and Nitrogen - Google Patents

Abstract

The present invention relates to a method for manufacturing a porous carbon material in which boron and nitrogen are simultaneously doped to a carbon-based material and then a porous structure is secured through activation treatment to finally simultaneously boron and nitrogen are doped. The material is excellent in electrochemical activity and storage capacity due to the formation of a bond of boron and nitrogen, and has excellent performance as an electrochemical catalyst and can be utilized as an electrode material for a supercapacitor, a fuel cell, and a redox flow cell.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for preparing a porous carbon material doped with boron and nitrogen simultaneously,

The present invention relates to a method for producing a porous carbon material doped with boron and nitrogen at the same time, more specifically, boron and nitrogen are doped into a carbon-based material at the same time, followed by activation treatment to secure a porous structure, To a method for producing a porous carbon material doped simultaneously.

As recent energy issues have created a need for sustainable energy sources, there is also a growing demand for energy storage and conversion technologies for efficient energy production and utilization. Particularly, researches on a fuel cell that directly converts the chemical energy of the fuel into electric energy, a supercapacitor which is a high-capacity electric energy storage device, and a next generation secondary battery such as a redox flow battery are actively conducted .

In the case of fuel cells, research on the catalyst materials to be used for the anode of the battery among the various fields is proceeding most. The Oxygen Reduction Reaction (ORR) at the anode of the fuel cell is much slower than the hydrogen oxidation reaction (HOR) occurring at the anode, This is because it has a great influence on. Due to the high cost of platinum-based catalysts, which are generally known to be highly efficient for ORRs, alternatives to carbon materials have been studied with doped heteroatoms such as boron or nitrogen (Bashyam, R. & Zelenay, P ., Nature, 2006, 443: . 63; Liang, YY et al, Nat Mater, 2011, 10: 780). However, boron and nitrogen are doped at the same time.

Next, it is widely known that, in the case of a supercapacitor, the storage capacity, which is the largest factor of performance, is proportional to the area of the plate on which the storage is performed. However, if the surface area is increased, the entire super capacitor will increase in size, so it is more efficient to have a larger effective area than the surface area. In light of this, the majority of studies have focused on porous carbon materials with a wide surface area. In particular, activated carbon prepared by heat treatment of a carbon precursor at a high temperature has been used commercially in supercapacitors (Pandolfo et al ., Journal of Power Sources, 2006, 157: 11).

There are two main ways to increase the surface area of carbon materials. The first is physical activation, which utilizes a gas that acts as an oxidant at high temperatures. The gas reaction can greatly increase the volume and surface area of the pores present in the carbon material, and temperature and reaction time are important parameters. The second is chemical activation, which proceeds at a lower temperature than the physical activation, and has the advantage of a shorter holding time and a relatively high yield. Reagents such as potassium hydroxide (KOH), H ₃ PO ₄ , and ZnCl ₂ are mainly used for chemical activation. Of these, potassium hydroxide is widely used because it forms very small pores and high surface area (Wang et al ., Journal of Materials Chemistry, 2012, 22: 23710).

The redox flow cell is characterized by its flexible design, high safety and long lifetime. However, low energy densities and efficiencies can be seen as obstacles to commercialization. In order to overcome these problems, electrode materials with excellent performance are required. Each electrode material contributes to the driving of the cell by promoting oxidation / reduction reaction of the redox couple, so that high conductivity, high surface area, chemical stability, and structural stability are required. Therefore, porous carbon materials have been studied as suitable materials.

Thus, the catalytic activity of the fuel cell anode, the storage capacity of the supercapacitor, and the performance of the redox flow cell electrode have a significant effect on the doping and surface area of the heteroatom. However, there have been few attempts to study the effect of boron and nitrogen heteroatoms at the same time on the formation of active sites, and it has been attempted to simultaneously increase the surface area through heteroatom doping and activation treatment, And there is no example of using the redox flow battery at the same time.

Accordingly, the present inventors have made intensive efforts to produce a carbon material that can be simultaneously used in a fuel cell, a supercapacitor, or a redox flow cell. As a result, the carbon material produced through the activation treatment of the carbon precursor and the simultaneous doping of boron and nitrogen, Electrode, a supercapacitor, and an electrode of a redox flow cell. Thus, the present invention has been completed.

It is an object of the present invention to provide a method for producing a porous carbon material in which boron and nitrogen are simultaneously doped from various carbon precursors.

Another object of the present invention is to provide an electrode material for a fuel cell, a supercapacitor, and a redox flow cell, which exhibits excellent performance as a porous carbon material doped with boron and nitrogen simultaneously produced by the above production method.

(A) mixing a carbon precursor, a boron precursor and a nitrogen precursor and heating and reacting to obtain a boron and nitrogen co-doped carbon material; And (b) adding an activator to the boron and nitrogen co-doped carbon material and activating to obtain a porous carbon material.

The present invention also provides boron and nitrogen co-doped porous carbon materials produced by the above process.

The present invention also provides an electrode material comprising a boron and nitrogen co-doped porous carbon material.

The production process according to the present invention is an economical process for producing a porous carbon material doped with boron and nitrogen simultaneously by a simple process of heat treatment, addition of activator and desalination, and mass production is possible. In addition, the process according to the present invention is more universally applicable than conventional processes in a method applicable to various kinds of boron, nitrogen and carbon precursors.

The carbon material produced by the present invention has excellent electrochemical activity and excellent performance as a storage capacity and an electrochemical catalyst due to the generation of a bond between boron and nitrogen, and can be utilized as an electrode material for a supercapacitor, a fuel cell, and a redox flow cell But also as a catalyst, an adsorbent or a gas separation medium.

1 is a diagram schematically illustrating a method of manufacturing a BN-AC according to Embodiment 1 of the present invention.
2 is a photograph of a BN-AC sample prepared according to Example 1 of the present invention.
3 is a graph showing a cyclic voltammetry (CV) measurement for the oxygen reduction reaction of BN-AC in Example 1 of the present invention.
4 is a graph showing a cyclic voltammetry (CV) measurement using BN-AC as a supercapacitor electrode in Example 1 of the present invention.
FIG. 5 is a graph showing a capacitance measured by a charge-discharge test when BN-AC is used as a supercapacitor electrode in Example 1 of the present invention.
FIG. 6 shows the activity of BN-AC prepared according to Example 1 of the present invention on an anode in a Zn-Br redox flow cell.
7 is a diagram schematically illustrating a method of manufacturing a BN-PAN according to a second embodiment of the present invention.
8 is a photograph of a BN-PAN sample prepared according to Example 2 of the present invention.
FIG. 9 is a graph showing a cyclic voltammetry (CV) measurement for the oxygen reduction reaction of BN-PAN in Example 2 of the present invention.
10 is a graph showing a cyclic voltammetry (CV) measurement using BN-PAN as a supercapacitor electrode in Example 2 of the present invention.
FIG. 11 is a graph showing a storage capacitance measured through a charge-discharge test when BN-PAN is used as a supercapacitor electrode in Example 2 of the present invention.
FIG. 12 shows the activity of the anode in the Zn-Br redox-flow battery with respect to BN-PAN according to Example 2 of the present invention.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein is well known and commonly used in the art.

In the present invention, it was confirmed that the carbon material prepared through the activation treatment and the simultaneous doping of boron and nitrogen to the carbon precursor can be used as the electrode of the fuel cell, the supercapacitor, and the electrode of the redox flow cell.

Thus, in one aspect, the present invention relates to a process for the production of carbon nanotubes comprising: (a) mixing a carbon precursor, a boron precursor and a nitrogen precursor and heating and reacting to obtain a boron and nitrogen co-doped carbon material; And (b) adding an activating agent to the boron and nitrogen co-doped carbon material and activating the porous carbon material to obtain a porous carbon material.

The carbon precursor used in the step (a) of the present invention may be a material in which carbon constitutes at least 40%, preferably at least 70% of the total mass, and one element of boron or nitrogen is included in the composition. More specifically, amorphous carbon materials such as activated carbon, carbon black, charcoal and the like; Crystalline carbon materials such as graphite, graphene and the like; And polyacrylonitrile (PAN), polyaniline (PANI), and the like, but the present invention is not limited thereto.

The boron precursor used in step (a) may be at least one selected from the group consisting of boron oxide (B ₂ O ₃ ), boric acid (H ₂ BO ₃ ), lithium boron hydride (LiBH ₄ ), sodium boron hydride (NaBH ₄ ) fluoride (KBH _4), magnesium boron hydride _{(Mg (BH 4) 2)} , calcium boron hydride _{(Ca (BH 4) 2)} , strontium boron hydride (Sr (BH _{4) 2)} and ammonia borane (NH ₃ BH ₃ ).

The nitrogen precursor used in step (a) may be at least one selected from the group consisting of polypyrrole polyaniline, melamine (C ₃ H ₆ N ₆ ), N, N'-bis (2,6-diisopropyphenyl) 4,9,10-perylenetetracarboxylicdiimide), polyacrylonitrile (polyacrylonitrile, PAN), urea _{(CO (NH 2) 2)} , ammonia (NH _3), ammonium hydroxide (NH ₄ OH), hydrazine (N ₂ H ₄₎ And ammonia borane (NH ₃ BH ₃ ).

The reaction of step (a) may be carried out at a rate of 1 to 10 ° C / min under an inert gas condition and maintained at 500 to 1300 ° C for 0.5 to 4 hours. At this time, the flow rate of the inert gas is preferably 20 to 200 ml / min.

The step (a) may further comprise (a ') removing and washing the salt from the boron and nitrogen co-doped carbon material. This step is to remove the salt contained in the obtained carbon material, and it can be treated with hot water at 40 to 90 ° C. And further washing the carbon material washed with hot water with alcohol. The alcohol may be at least one selected from the group consisting of methanol, ethanol and propanol. The step of drying the boron and nitrogen co-doped porous carbon material washed with hot water or hot water and alcohol is preferably performed in an oven at 90 to 130 ° C for 1 to 2 days.

The activating agent may be selected from the group consisting of potassium hydroxide, sodium hydroxide, H ₃ PO ₄ and ZnCl ₂ . The mixing ratio of the boron and nitrogen co-doped carbon material and the activator is preferably 1: 0.1 to 1: 5. In this case, the mixing method can be physically mixed using a solid activating agent, and it is also possible to dissolve the activating agent in water, alcohol or organic solvent, and then mix it with boron and nitrogen simultaneously doped carbon materials, followed by evaporation.

The activation treatment in step (b) may be maintained at 600 to 1200 ° C. for 0.5 to 2 hours under an inert gas atmosphere. If the heat treatment temperature is less than 600 ° C, the surface area of the carbon material decreases. If the temperature exceeds 1200 ° C, the yield decreases and the corrosion of the heat treatment apparatus becomes severe, which affects the durability. At this time, a temperature raising rate of 1 to 10 DEG C / min is suitable. If the heating rate is less than 1 占 폚 / min, the heat treatment time is unnecessarily increased. If the heating rate is more than 10 占 폚 / min, the pores are not sufficiently developed. At this time, in order to prevent the carbon material from being oxidized and disappearing, the reaction is performed under an inert gas such as nitrogen or argon, and may further include other gases such as carbon dioxide (CO ₂ ) for additional reaction to the polymer.

In another aspect of the present invention, there is also provided an electrode material comprising a boron and nitrogen co-doped porous carbon material or a boron and nitrogen co-doped porous carbon material produced by the above manufacturing method.

The boron and nitrogen co-doped porous carbon materials prepared using the method according to the present invention are characterized in that boron and nitrogen are simultaneously doped in the carbon structure and have a charge storage capacity of 100 to 300 F / g, The peak potential may be between -0.15 and -0.30V. The carbon material is suitable for use as an electrode material for a supercapacitor or a fuel cell. In addition, since it is active on bromine oxidation / reduction (Br ₂ + 2e ^- ⇔ 2Br ^- ), it can be used as anode material in Zn-Br redox flow cell.

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these embodiments are for illustrative purposes only and that the scope of the present invention is not limited by these embodiments.

[Example]

Example  1: Activated carbon (AC) from boron and nitrogen simultaneously Doped  Porous carbon BN -AC)

A method for producing a porous carbon material in which boron and nitrogen are simultaneously doped from activated carbon will be described in detail with reference to FIG.

Activated carbon (AC) was obtained from Darco and boric acid and urea were used as boron and nitrogen precursors, respectively.

7 g each of activated carbon, boric acid and urea were added and physically mixed. Then, the mixture was placed in a furnace, placed in a furnace reactor, and argon flowed at a flow rate of 50 ml / min. At this time, the reaction conditions were raised to 1000 at room temperature with a heating rate of 5 / min, and the temperature was maintained for 2 hours. The sample was then cooled to room temperature and the resulting sample was washed with deionized water (DIW). The cleaning process is as follows.

100 ml of distilled water was poured into a 100 ml beaker containing the reacted sample, and the mixture was stirred at 500 rpm for 85 to 15 minutes. The sample was then submerged and the solution above was removed. After repeating this step twice, the same procedure was repeated 5 times using distilled water at room temperature. Finally, the procedure was repeated using ethanol and the sample was dried in a 120 oven for 12 hours or more.

Carbon materials doped with boron and nitrogen were activated by KOH to form porous carbon. The concrete procedure is as follows.

5 g of boron and nitrogen-doped carbon material and 5 g of KOH were mixed and placed in a furnace in a furnace in a crucible, and argon was flowed at a flow rate of 50 ml / min. At this time, the reaction conditions were raised from room temperature to 850 at a heating rate of 5 / min, and the temperature was maintained for 2 hours. The sample was then cooled to room temperature and the resulting sample was washed with hydrochloric acid (HCl) and distilled water. Concretely, 100 ml of hydrochloric acid was poured into a 100 ml beaker containing the reacted sample, and the mixture was stirred at 500 rpm for 50 to 15 minutes. The sample was then submerged and the solution above was removed. After repeating this step twice, the same procedure was repeated 5 times using distilled water at room temperature. Finally, the procedure was repeated using ethanol and the sample was dried in a 120 oven for 12 hours or more.

The completed boron and nitrogen-doped porous carbon material (BN-AC) identified in FIG. 2 was used as a catalyst for an oxygen reduction reaction (ORR), a reaction occurring at the anode of a fuel cell. The activity against ORR was measured using a glass carbon electrode as a working electrode, a platinum wire as a counter electrode and Ag / AgCl as a reference electrode and a basic electrolyte aqueous solution of 1M NaOH. As a result, the peak potential at which the current is maximized in an oxygen saturated state was observed to be -0.197 V as shown in FIG.

Further, the storage capacity was measured as shown in Fig. 4 by using the completed boron- and nitrogen-doped porous carbon material (BN-AC) as the electrode material of the supercapacitor. FIG. 5 shows the results of charging / discharging the BN-AC with nickel on a 6M KOH water-soluble electrolyte and shows a storage capacity of 153 F / g based on a current density of 1 A / g.

FIG. 6 is a graph showing a CV measurement for a QBr (quaternary bromine) solution. It shows that BN-AC prepared according to Example 1 through the oxidation and reduction peaks can be utilized as the anode of a Zn-Br redox flow cell have.

Example  2: Polyacrylonitrile ( 폴리acrylonitrile , PAN) with boron and nitrogen simultaneously Doped  Porous carbon BN -PAN)

A method for producing a porous carbon material in which boron and nitrogen are simultaneously doped from polyacrylonitrile (PAN) will be described in detail with reference to FIG.

In this example, PAN was used as a carbon precursor and nitrogen precursor, and boric acid was used as a boron precursor.

4 g of stabilized PAN was mixed with 4 g of boric acid under air condition of 280 ° C, and then put into a furnace in a furnace in a crucible, and argon was flowed at a flow rate of 50 ml / min. At this time, the reaction conditions were raised from room temperature to 850 at a heating rate of 5 / min, and the temperature was maintained for 2 hours. The sample was then cooled to room temperature and the resulting sample was washed with deionized water (DIW). The cleaning process is as follows.

100 ml of distilled water was poured into a 100 ml beaker containing the reacted sample, and the mixture was stirred at 500 rpm for 85 to 30 minutes. The sample was then submerged and the solution above was removed. After repeating this step twice, the same procedure was repeated 5 times using distilled water at room temperature. Finally, the procedure was repeated using ethanol and the sample was dried in a 120 oven for 12 hours or more.

The boron and nitrogen doped carbon materials were activated by KOH to complete the porous carbon. The concrete procedure is as follows.

1.8 g of boron and nitrogen-doped carbon material and 3.6 g of KOH were mixed and placed in a crucible in a furnace reactor, and argon was flowed at a flow rate of 50 ml / min. At this time, the reaction conditions were raised from room temperature to 850 at a heating rate of 5 / min, and the temperature was maintained for 2 hours. The sample was then cooled to room temperature and the resulting sample was washed with hydrochloric acid (HCl) and distilled water. Concretely, 100 ml of hydrochloric acid was poured into a 100 ml beaker containing the reacted sample, and the mixture was stirred at 500 rpm for 50 to 30 minutes. The sample was then submerged and the solution above was removed. After repeating this step twice, the same procedure was repeated 5 times using distilled water at room temperature. Finally, the procedure was repeated using ethanol and the sample was dried in a 120 oven for 12 hours or more.

The completed boron and nitrogen-doped porous carbon material (BN-PAN) identified in FIG. 7 was used as a catalyst for the oxygen reduction reaction (ORR), which is a reaction occurring at the anode of the fuel cell. The activity against ORR was measured using a glass carbon electrode as a working electrode, a platinum wire as a counter electrode and Ag / AgCl as a reference electrode and a basic electrolyte aqueous solution of 1M NaOH. As a result, the peak potential at which the current is maximized in an oxygen saturated state was observed at -0.208 V as shown in FIG.

Also, the capacitances were measured as shown in FIGS. 9 and 10 by using the completed boron and nitrogen-doped porous carbon material (BN-AC) as the electrode material of the supercapacitor. BN-AC was attached to nickel and confirmed by charging / discharging curve under a 6 M KOH water-soluble electrolyte. The results are shown in FIGS. 10 and 11 and showed a storage capacity of 225 F / g based on a current density of 1 A / g .

FIG. 12 is a graph showing the CV measurement for a QBr (quaternary bromine) solution. It shows that BN-PAN prepared according to Example 2 through oxidation and reduction peaks can be used as a cathode of a Zn-Br redox flow cell have.

While the present invention has been particularly shown and described with reference to specific embodiments thereof, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. something to do. Accordingly, the actual scope of the present invention will be defined by the appended claims and their equivalents.

Claims (16)

A method of producing a boron and nitrogen co-doped porous carbon material comprising the steps of:
(a) mixing and heating and reacting a carbon precursor, a boron precursor and a nitrogen precursor to obtain a boron and nitrogen co-doped carbon material; And
(b) adding an activator to the boron and nitrogen co-doped carbon material and performing an activation treatment to obtain a porous carbon material,
The carbon precursor and the nitrogen precursor are polyacrylonitrile or polyaniline.
3. The method of claim 1, further comprising the step of removing (a ') the boron and nitrogen co-doped carbon material after the step (a) and washing the boron and nitrogen co-doped porous carbon material.
The method of claim 1 wherein the boron precursor is selected from the group consisting of boron oxide (B ₂ O ₃ ), boric acid (H ₂ BO ₃ ), lithium boron hydride (LiBH ₄ ), sodium boron hydride (NaBH ₄ ), potassium boron hydride (KBH _4), magnesium boron hydride _{(Mg (BH 4) 2)} , calcium boron hydride _{(Ca (BH 4) 2)} , strontium boron hydride (Sr (BH _{4) 2)} and ammonia borane (NH ₃ BH < ₃ >). ≪ / RTI >
The method of claim 1, wherein the nitrogen precursor is selected from the group consisting of polypyrrole, polyaniline, melamine (C ₃ H ₆ N ₆ ), N, N'-bis (2,6-diisopropylphenyl) (N, N'-bis (2,6-diisopropyphenyl) -3,4,9,10-perylenetetracarboxylic diimide, PDI), polyacrylonitrile (PAN) component _{(CO (NH 2) 2)} , adding ammonia (NH _3), ammonium hydroxide (NH ₄ OH), hydrazine (N ₂ H ₄₎ and ammonia borane (NH ₃ BH ₃₎ with at least one member selected from the group consisting of Wherein the boron and nitrogen co-doped porous carbon material is a mixture of boron and nitrogen.
The method of claim 1, wherein the carbon precursor further comprises an amorphous carbon material, a crystalline carbon material, or a polymer.
The method of claim 1, wherein the boron and nitrogen co-doped carbon material is boron and nitrogen are simultaneously doped in the carbon structure.
The method of claim 1, wherein the step (a) comprises heating the boron and nitrogen simultaneously doped with boron and nitrogen at an elevated rate of 1 to 10 ° C / min under inert gas conditions and annealing at 500 to 1300 ° C for 0.5 to 4 hours. Method of manufacturing a material.
The method of claim 2, wherein the step (a ') is performed by washing with hot water or alcohol at 40 to 90 ° C and then drying the boron and nitrogen co-doped porous carbon material.
The method of claim 1, wherein the activator is at least one selected from the group consisting of potassium hydroxide, sodium hydroxide, H ₃ PO _4, and ZnCl ₂ .
The method of claim 1, wherein the boron and nitrogen co-doped carbon material and the activator are mixed in a weight ratio of 1: 0.1 to 1: 5.
The method according to claim 1, wherein the activating process in step (b) is performed at a temperature of 1 to 10 ° C / min under an inert gas atmosphere, and is maintained at 600 to 1200 ° C for 0.5 to 2 hours. A method for producing a doped porous carbon material.
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