KR20150076057A - Heteroatoms-containing Porous Carbon using Seaweed and Fabrication Method thereof - Google Patents

Abstract

According to the present invention, a method for preparing a porous carbon body containing heterogeneous elements includes the steps of: a) thermally decomposing algae in an inert atmosphere to prepare an inorganic-carbon body which is a carbon body containing inorganic compound particles; and b) removing the inorganic compound particles in the inorganic-carbon body through an acid leaching process.

Description

TECHNICAL FIELD [0001] The present invention relates to porous carbon materials containing heteroatoms and seaweeds,

The present invention relates to a porous carbon body containing a heteroatom and a method for producing the porous carbon body. More particularly, the present invention relates to a porous carbon body containing a heteroatom, The present invention relates to a heterogeneous element-containing porous carbon body containing a hetero-element and capable of being used as an electrode material of a chemical reaction, an electrode material of a water treatment apparatus, or an adsorbent, and a method for producing the same.

Energy demand is surging worldwide due to industrial development and population growth, but production of petroleum / natural gas, which is the main energy source, is expected to decrease gradually from about 2020. It is urgent to research and develop alternative clean energy sources that do not pollute the environment with exhaustion of these fossil fuels.

In 1997, the Kyoto Protocol for the Reduction of GHGs was adopted and 119 countries including Korea ratified it, and mandatory reduction of greenhouse gas emissions and burden of reduction of greenhouse gas are underway.

Although the technology that uses various natural resources such as solar energy, wind power, and hydrogen energy as the energy source is being researched and developed, it does not suffer from the thermodynamic limitation (carnot efficiency) by the direct power generation method and has a high efficiency of generation and a constant efficiency even in a wide load range Fuel cell technology is regarded as an alternative clean energy due to the fact that noise and vibration are very small, it is possible to produce dispersed electric power, and the power generation capacity can be easily controlled without discharging air pollutants such as NOx have.

A fuel cell is an energy conversion device that converts chemical energy possessed by fuel directly into electric energy by an electrochemical reaction. A fuel cell system is composed mainly of stacks of fuel cell / electrolyte / air electrode fuel cell basic unit cells connected in series and in parallel. A typical fuel cell system includes a stack for producing electricity, A fuel processor, a switching device for converting the DC power produced in the stack to AC power, and a heat recovery device for recovering heat.

Fuel cells can be used in a wide variety of applications, such as alkaline fuel cells (AFC), phosphoric acid fuel cells (PAFC), polymer electrolyte fuel cells (PEMFC), molten carbonate fuel cells (MCFC), solid oxide fuel cells (SOFC) ), AFC, PEMFC, and DMFC are very low in operation temperature compared to fuel cells having different operating temperatures, and are more preferable in terms of clean energy source as methanol or hydrogen is used as fuel.

 However, despite these advantages, low-temperature fuel cells such as AFC, PEMFC, and DMFC use platinum as a catalyst, and therefore expensive expensive catalysts must be solved for use.

For this purpose, the amount of platinum used as a catalyst is minimized through alloying with other metals as disclosed in Korean Patent No. 1117066 and Korean Laid-Open Patent Application No. 2013-0139577, or a platinum catalyst such as Korean Patent Publication No. 2013-0068826 And metal-organic complexes that can replace the metal-organic complexes. However, there are limitations in cost reduction in terms of reducing the amount of platinum through alloying, and in the case of alternative catalysts, the development of materials that can be manufactured in a simple and environmentally friendly manner with low cost raw materials while having excellent activity and long- Are continuously required.

Korea Patent No. 1117066 Korean Patent Publication No. 2013-0139577 Korean Patent Publication No. 2013-0068826

The present invention has an excellent oxygen reducing activity and stability corresponding to platinum and can replace a platinum catalyst of a fuel cell and can be used as an electrode material or an adsorbent for a secondary battery, a super capacitor, a solar cell, a sensor, a storage desalination device (CDI) And which can be mass-produced in a short time by a simple method using a low-cost raw material, and a method for producing the same.

The method for producing a porous carbon body containing a hetero-element according to the present invention comprises the steps of: a) pyrolyzing algae in an inert atmosphere to produce an inorganic-carbon body having carbon atoms containing inorganic compound particles; And b) leaching the inorganic compound particles of the inorganic-carbon body by leaching.

In the production method according to an embodiment of the present invention, the heteroelement originates from algae, and may include at least N and S.

In the manufacturing method according to an embodiment of the present invention, the relative ratio of the bonding state of the hetero elements can be controlled by controlling the thermal decomposition temperature.

In the production method according to an embodiment of the present invention, the inorganic compound may include at least a metal halide, a metal oxide, or a mixture thereof.

In the production method according to an embodiment of the present invention, the porous carbon body may have a turbostratic structure.

In the production method according to an embodiment of the present invention, the pyrolysis temperature in step a) may be 800 to 1100 ° C.

In the production method according to an embodiment of the present invention, 15 to 60% of N contained in the porous carbon body is quaternary-N bonded, 20 to 40% is pyridinic N, And 35 to 60% of the S contained in the porous carbon body may be a thiopene-S bonded state.

In the production method according to an embodiment of the present invention, the content of N and S in the porous carbon body may be 3 to 6.5% by atom.

In the production method according to an embodiment of the present invention, the porous carbon body may have a BET specific surface area of 650 to 1450 m ² / g, a microporosity of 0.2 to 0.85 cm ³ / g and a meso porosity of 0.2 to 1.10 cm ³ / g have.

In the production method according to an embodiment of the present invention, the porous carbon body may be a catalyst for a fuel cell.

The present invention includes a porous carbon body produced by the above-described production method.

The present invention includes a membrane-electrode composite for a fuel cell containing a porous carbon body manufactured by the above-described production method.

The present invention includes a fuel cell containing a porous carbon body manufactured by the above-described production method as a catalyst of an electrode.

The porous carbon body containing a hetero-element according to the present invention is a porous carbon body having a turbostratic structure prepared by pyrolysis of algae and acid leaching treatment, and has a BET specific surface area of 650 to 1450 m ² / g, A porosity of 0.2 to 0.85 cm ³ / g and a meso porosity of 0.2 to 1.10 cm ³ / g, and contains at least N and S.

In the porous carbon body according to one embodiment of the present invention, 15 to 60% of the N contained in the porous carbon body is a quaternary-N bonded state, and 20 to 40% is pyridinic N ), And 35 to 60% of the S contained in the porous carbon body may be a thiophene-S bonded state.

In the porous carbon body according to an embodiment of the present invention, the BET specific surface area may be 1000 to 1450 m ² / g.

The present invention includes a membrane-electrode composite for a fuel cell containing the above-described porous carbon body.

The present invention includes a fuel cell containing the above-described porous carbon body as a catalyst of an electrode.

The production method according to the present invention can produce a porous carbon body using an extremely low cost natural resource which exists abundantly and can produce a porous carbon body through an extremely simple and easy process such as a single pyrolysis step and an acid leaching step It is possible to construct a simple and easy process with low cost raw materials and low cost, and thus it is advantageous in that a high quality catalyst having an excellent catalytic activity and an oxygen reduction reaction activity corresponding to a Pt catalyst can be produced.

The porous carbon body according to the present invention not only has an oxygen reduction reaction activity corresponding to a commercially available Pt catalyst but also has durability and methanol stability superior to that of a conventional Pt catalyst and has an advantage of being able to replace the Pt catalyst of the fuel cell immediately And can be manufactured through a simple process from low-cost natural resources, it is possible to reduce the production cost of the fuel cell, thereby promoting the commercialization of the fuel cell.

In addition, since the porous carbon body according to the present invention has a high porosity and a specific surface area and has a stratified structure excellent in electrical conductivity and activity, it can be applied to various electrochemical devices such as a secondary battery, a superpatterner, It can be used as an electrode material of a water treatment apparatus such as a desalination apparatus (CDI) and can be used as an adsorbent.

1 is a scanning electron microscope (SEM) photograph of the porous carbon material produced in Example,
FIG. 2 is a photograph showing a transmission electron microscope photograph of the porous carbon body produced in the example,
FIG. 3 shows the nitrogen-adsorption isotherm measurement results of the raw materials and the porous carbon bodies produced in Examples,
FIG. 4 shows the results of X-ray diffraction analysis of the carbon bodies produced in Examples,
FIG. 5 is a graph showing a relative binding state fraction of N and S contained in the carbon body produced in the examples,
FIG. 6 is a graph showing the result of LSV (linear sweep voltammetry) measurement of a catalyst electrode manufactured using the carbon body manufactured in the example,
FIG. 7 is another diagram showing the result of measurement of the LSV (linear sweep voltammetry) of the catalyst electrode manufactured using the carbon body manufactured in the embodiment,
8 is a graph showing a CV measurement result of the catalyst electrode manufactured using the carbon body manufactured in the example,
FIG. 9 is another view showing the CV measurement result of the catalyst electrode manufactured using the carbon body manufactured in the embodiment,
10 is a graph showing the measurement of the resistivity according to the pressure of the porous carbon body manufactured in the example,
11 is a graph showing the conductivity, the mesophore specific surface area, the nitrogen content in the heteroelement, and the onset potential of the porous carbon body produced in Examples.

Hereinafter, the porous carbon body according to the present invention and a method for producing the same will be described in detail. Here, unless otherwise defined, technical terms and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. In the following description, the gist of the present invention is unnecessarily blurred And a description of the known function and configuration will be omitted.

As a result of deepening research on catalytic materials capable of mass production at low cost and simple process, seaweeds themselves, which are abundant natural resources, can be used as carbon sources, and as a result, In consideration of the fact that heteroatoms suitable for the activity of the platinum-based catalyst are already contained in the seaweeds, the carbonaceous bodies which can be produced by a simple method but have an extremely high specific surface area and have an activity corresponding to the platinum- And a method for producing the same.

The method for producing a porous carbon body containing a hetero-element according to the present invention comprises the steps of: a) pyrolyzing algae in an inert atmosphere to produce an inorganic-carbon body having carbon atoms containing inorganic compound particles (carbonization step); And b) leaching the inorganic compound particles of the inorganic-carbon body by acidic leaching (hereinafter, acid leaching step).

As described above, the production method according to the present invention can produce a porous carbon body activated by a single carbonization (pyrolysis) step by using algae as a precursor of carbon, and further, It is possible to produce a porous carbon body containing a hetero-element without a separate doping process. In addition, since the algae, which are abundantly present and extremely low-cost natural resources and easy to supply and receive, are used as precursors, the cost for raw materials can be remarkably reduced. In addition, it is possible to produce a porous carbon body having a high specific surface area, which is unnecessary to use a mold for a porous structure, is expensive, sensitive to handling and process parameters and does not use toxic organic compounds. Further, since a porous carbon material activated by a single carbonization (pyrolysis) is produced, there is an advantage that a post-treatment process for activating carbon is unnecessary.

The Applicant has further intensively studied the production of porous carbon bodies by pyrolysis of seaweeds. As a result, it is possible to produce porous carbon bodies containing a certain amount of hetero elements even by only the pyrolysis step. However, There is a limit. Accordingly, after inorganic substances (including inorganic elements and inorganic particles) such as metals, halides, oxides and the like already contained in seaweeds themselves are granulated or remained in the step of carbonization (pyrolysis), these fine particles are subjected to subsequent acid leaching , The porous structure can be formed and the specific surface area can be remarkably improved. Further, in order to be used as a catalyst for a fuel cell, it is preferable to remove elements other than the active elements that impart or enhance catalytic performance. In this respect also, the active elements, such as the heteroatom and the substances other than carbon, are removed through the above-mentioned acid leaching process, so that a porous carbon body containing a hetero-element having extremely excellent purity can be produced.

That is, as described above, the production method according to the present invention uses the seaweed as a precursor of the porous carbon body, and the heterogeneous element, which is an active element that imparts or enhances the catalytic function, also originates from seaweed, (Including inorganic elements and inorganic particles) are granulated and removed through acid leaching, a porous carbon body having an extremely high specific surface area and having excellent purity can be produced. At this time, the meaning of the particles may mean that the inorganic materials contained in the seaweed are used as a source of material, and nucleation and / or growth of the inorganic compound occurs in the carbonization step.

In the production method according to an embodiment of the present invention, the heteroelement originating from algae may include at least N and S. That is, the porous carbon body may contain at least N and S, and may specifically contain N, S and O, and more specifically may contain N, S, O and P. N, S, O and P are known as active elements of the oxygen reduction reaction. O 2 also contributes to the oxygen reduction activity, but mainly N, S and P have a greater effect on the oxygen reduction reaction. It is also known that when two or more active elements are mixed rather than a single active element, the catalytic activity during the oxygen reduction reaction is further improved.

In the production method according to an embodiment of the present invention, the inorganic compound particles may include a metal halide, a metal oxide, or a mixture thereof. Metals of metal halides and metals and oxygen of halogens and metal oxides can be derived from the minerals (inorganic elements) contained in seaweeds. The present invention is characterized in that, in the carbonization step, the algae are carbonized so that the particulate phase of the inorganic compound is formed and / or remains from the inorganic substance contained in the algae, and then the inorganic compound particles are pored It is needless to say that the present invention can not be limited by the specific kind of the inorganic compound since the specific surface area and purity of the porous carbon body are improved by removing the inorganic compound particles through an acid leaching step. However, as a specific and non-limiting example for facilitating a clear understanding of the present invention, inorganic substances, which are generally known to be mainly contained in seaweeds, are Na, Cl, Mg and the like, and thus the metal halide may include NaCl, The metal oxide may include MgO.

In the production method according to an embodiment of the present invention, the heat treatment temperature may be determined depending on whether or not the inorganic-carbon body is formed, the pore structure of the porous carbon body to be produced, the crystallographic structure of the porous carbon body, Content and the bonding state of the different elements.

The content of the hetero-element remaining in the porous carbon body due to seaweeds can be increased as the pyrolysis temperature is lower. Accordingly, when only the increase in activity due to the enhancement of the content of the different elements is considered, the algae can be thermally decomposed at a temperature as low as possible. However, as a result of many experiments and analyzes, it is also important to improve the content of heteropolysaccharides in order to improve the catalytic activity of the oxygen reduction reaction. However, the binding state of the heterogeneous elements and the specific surface area of the porous carbon bodies are also important . Based on this finding, the pyrolysis of the carbonization step is preferably carried out at 800 to 1100 ° C, preferably 800 to 1050 ° C, more preferably 900 to 1050 ° C. The range of the pyrolysis temperature is such that the pore structure of the porous carbon body is not collapsed while maintaining the content of the appropriate hetero element, the specific surface area is improved by the pore forming agent, and the electrical conductivity is improved And is a temperature range in which the heterogeneous element can be contained in the porous carbon body in the bonding state improving the catalytic activity of the oxygen reduction reaction.

From the viewpoint of the porous structure, inorganic compound particles contained in seaweeds are not well formed at a temperature lower than 800 占 폚, or even if they are formed, they can have an extremely minute embedded shape in the carbon matrix, There is a risk that it is formed or not easily removed. When the pyrolysis temperature is higher than 1100 ° C, the risk of volatilization is removed at the carbonization stage rather than the inorganic compounds contained in the seaweed, and the microporous structure formed on the carbon body by the pyrolysis of the seaweed itself is collapsed There is a danger.

Specifically, by performing pyrolysis at 800 to 1100 占 폚, a porous carbon body having a BET specific surface area of 650 to 1450 m ² / g can be produced. Preferably, pyrolysis is carried out at 800 to 1050 占 폚, whereby a porous carbon body having a BET specific surface area of 900 to 1450 m ² / g can be produced. More preferably, pyrolysis is carried out at 900 to 1050 占 폚, whereby a porous carbon body having a BET specific surface area of 1000 to 1450 m ² / g can be produced.

Further, according to IUPAC definition, pyrolysis is performed at 800 to 1100 占 폚 when pores having a diameter of 2 nm or less are referred to as micropores, pores having a diameter of 2 nm to 50 nm are referred to as mesopores, and pores having a diameter of 50 nm or more are referred to as macropores micro porosity (total volume of micropores per unit weight of the porous carbon material), 0.2 to 0.85 cm ³ / g, and a meso porosity (total volume of the meso pores per unit mass of the porous carbon material), 0.2 to 1.10 cm ³ / g porous Carbon bodies can be produced. The porous carbon material having a microporosity of 0.3 to 0.85 cm < ³ > / g and a meso porosity of 0.25 to 1.10 cm < ³ > / g can be produced by performing pyrolysis at 800 to 1050 deg. Even better, may be made of a porous carbon body is a thermal decomposition is carried out, whereby the micro porosity of 0.35 to 0.85 cm ³ / g, and a meso porosity of 0.7 to 1.10 cm ³ / g at 900 to 1050 ℃.

From the viewpoint of the heterogeneous element content, when the pyrolysis temperature exceeds 1100 ° C, the total content of N and S (element%) contained in the carbon body falls to less than 3%, and the catalytic activity There is a risk of failure. By performing pyrolysis at 800 to 1100 占 폚, the content of N and S contained in the carbon body may be 3 to 6.5% by atom. Both N and S may decrease in absolute content as the pyrolysis temperature increases, but the relative bonding state of each element may vary depending on its stability. That is, the absolute content of active elements including N and S may decrease as the pyrolysis temperature increases, but the relative ratio of the bound state of each element can be controlled by the pyrolysis temperature.

As described above, pyrolysis is carried out at 800 to 1100 占 폚, whereby at least one element selected from the group consisting of N, S and O (oxygen) containing at least N and S, And a porous carbon body containing P can be produced. Specifically, pyrolysis is carried out at 800 to 1100 占 폚 to prepare a porous carbon body containing 1.5 to 5.5 atomic% N and 0.7 to 1.5 atomic% S as a heteroelement . Further, pyrolysis is carried out at 800 to 1100 占 폚, whereby a porous carbon body containing 4 to 9 atomic% O in combination with N and S can be produced. The porous carbon body containing 2 to 5 atomic% of N and 1 to 1.5% of elemental S can be produced by pyrolysis at 900 to 1050 占 폚, preferably 7 To 9 atomic% (O atomic%) of O can be produced. At this time, a small amount of P may be contained in the produced porous carbon body, and substantially less than one element (%) of P may be contained.

The pyrolysis temperature can significantly affect not only the pore structure and the heterogeneous element content, but also the relative fraction of the bonded states of the heterogeneous elements. By performing pyrolysis at 800 to 1100 占 폚, N contained in the porous carbon body has a quaternary-N bonding state of 15 to 60% and a pyridinic N bonding state of 20 to 40% And S in the porous carbon body may have a thiopene-S bonding state of 35 to 60%. It is preferable that 20 to 60% of the total N contained in the porous carbon body is in a quaternary-N bonded state and 20 to 40% is in a pyridonic (N) bond state by controlling the thermal decomposition temperature to 900 to 1100 캜 pyridinic N) bonding state, and 35 to 60% of the total S contained in the porous carbon body may have a thiophene-S bonding state. More preferably, 40 to 60% of the total N contained in the porous carbon body may have a quaternary-N bonding state by adjusting the pyrolysis temperature to more than 900, specifically 950 to 1100 ° C , And 50 to 60% of the total S contained in the porous carbon body may have a thiopene-S bonding state. That is, depending on the pyrolysis temperature, the relative fraction of the bonded state of the different elements contained in the porous carbon body can be controlled. By adjusting the pyrolysis temperature to 900 to 1100 ° C, preferably 950 to 1100 ° C, N of the quaternary-N bond and the S of the thiophen-S bond, which are in a bonding state which promotes the bonding of the two groups.

The pore structure, the heterogeneous element content, and the bonding state of the heteroatom are affected by the thermal decomposition temperature acting as a main regulator, and the pore structure of the porous carbon body is not collapsed The pyrolysis temperature is preferably 800 to 1100 ° C, more preferably 800 to 1100 ° C so that the heterogeneous element can be contained in the porous carbon body in the bonding state in which the catalytic performance of the oxygen reduction reaction is improved. Deg.] C to 1050 < 0 > C, preferably 900 to 1050 [deg.] C, and even more preferably 950 to 1050 [ That is, the upper limit of the pyrolysis temperature may be 1050 ° C so as to maintain proper heterogeneous element content, prevent the collapse of the pore structure, produce an inorganic-carbon body, and improve the specific surface area. the lower limit of the pyrolysis temperature may be 950 ° C so that the relative fraction of S of the N and thiophene-S bonds of the quaternary-N bond can be significantly increased. Further, when the porous carbon body is produced by pyrolyzing at 950 to 1050 ° C, it has methanol stability superior to that of the conventional Pt / C, and the porosity, pore structure, crystallographic structure of the porous carbon body, Due to the content of the hetero-elements contained and the bonding state of the different elements, the Pt / C catalyst can be replaced with a commercially available Pt / C catalyst having an oxygen reduction reaction catalytic ability similar to that of a conventional Pt / C catalyst.

Although the pyrolysis is carried out at a high temperature ranging from 800 to 1100 ° C, the production method according to an embodiment of the present invention can produce carbon bodies of a turbostratic structure by pyrolysis including hetero elements and minerals contained in seaweeds . Accordingly, post-treatment for activation of the carbon body is not required, and the porous carbon body having the egg shell structure and containing the hetero-element can be produced by a single precursor and a single carbonization step.

The inert gas atmosphere at the carbonization step is not particularly limited, but may be a gas atmosphere selected from one or more of argon, nitrogen and helium. The pyrolysis time can be appropriately adjusted at a level at which sufficient pyrolysis takes place in consideration of the amount of seaweed to be treated, but can be performed for 3 to 8 hours as a non-limiting example.

Seaweeds used as raw materials may include green algae (Chlorophyta, green algae), red algae (Rhodophyta, red algae) and brown algae (Phaeophyta, brown algae). Green algae can be used for parasites and hearing, and brown algae such as seaweed and kelp can be mentioned. Red algae such as Kim and Ugukgasari can be mentioned. Since a porous carbon body containing a different element can be produced from all the seaweeds, the seaweed used as a raw material can be appropriately selected in consideration of the ease of purchase of the raw material and the unit cost of the raw material. If necessary, the seaweed used as raw material can be pretreated with washing, drying and cutting (crushing) to remove foreign matter adhering to the carbonization step algae.

The acid leaching step may be carried out using an acid solution used to leach out conventional inorganic particles. As a specific example, the acid leaching step can be carried out using a strong acid aqueous solution with a concentration of 1 to 5 moles, and the strong acid can include one or more acids selected from hydrochloric acid, sulfuric acid and nitric acid. The leaching time can be appropriately adjusted at a level at which sufficient leaching removal of the inorganic compound particles and undesired impurities takes into account of the amount of the inorganic-carbon substance to be treated, but it is a specific and non-limiting example, .

The porous carbon body manufactured by the above-described method for producing a porous carbon body may be used as an electrode material or an adsorbent for a secondary battery, a super capacitor, a solar cell, a sensor, a condensation desalination unit (CDI), or the like. In detail, the porous carbon body can be used as an anode active material of a secondary battery, an electrode material of a supercapacitor, an electrode material of a solar cell, an electrode material of CDI, or an electrode material of a sensor.

Preferably, the porous carbon body produced by the above-described method for producing a porous carbon body may be a catalyst for a fuel cell. That is, the above-described method for producing a porous carbon body may be a method for producing a catalyst for a fuel cell. Specifically, the porous carbon body may be used for an alkali fuel cell (AFC), a polymer electrolyte fuel cell (PEMFC), or a direct methanol fuel cell (DMFC) catalyst, and more specifically, an alkali fuel cell (AFC) (PEMFC), or a direct methanol fuel cell (DMFC).

The present invention includes a porous carbon body containing a hetero-element produced by the above-described production method.

The present invention includes a Membrane Electrode Assembly (MEA) for a fuel cell containing a hetero-element produced by the above-described production method. Specifically, the membrane electrode assembly may include an electrode including a porous carbon body manufactured by the above-described manufacturing method as a catalyst, and a gas diffusion layer for allowing fuel and air to be uniformly supplied to the electrode.

The present invention includes a fuel cell in which a porous carbon body containing a hetero-element produced by the above-described production method is provided as a catalyst. Specifically, the fuel cell includes an ion conductive electrolyte, a membrane electrode assembly including a porous carbon body manufactured by the above-described manufacturing method, and a bipolar electrode disposed on both sides of the membrane electrode assembly and having a predetermined flow channel for supplying fuel and air to both sides thereof. And may include a bipolar plate.

The present invention includes a porous carbon body containing a heterogeneous element. The porous carbon body according to the present invention is a porous carbon body having a turbostratic structure prepared by pyrolysis of algae and acid leaching treatment, and has a BET specific surface area of 650 to 1450 m ² / g, a microporosity of 0.2 to 0.85 cm ³ / g and a meso porosity of 0.2 to 1.10 cm < ³ > / g, and contains at least N and S. [

The porous carbon body according to an embodiment of the present invention may contain 3 to 6.5 atomic% of total N and S hetero atoms, 1.5 to 5.5 atomic% of N and 0.7 to 1.5 atomic% %) ≪ / RTI > In addition, the porous carbon body may further contain O together with N and S, and may contain O of 4 to 9 atomic%. At this time, the porous carbon body may further contain a trace amount of P less than one element (%).

More specifically, in the porous carbon body according to an embodiment of the present invention, N contained in the porous carbon body is a quaternary-N bonded state of 15 to 60% and a quaternary-N bonded state of 20 to 40% (pyridinic N) bonded state, and S contained in the porous carbon body may have a thiophen-S bonding state of 35 to 60%. More specifically, in the porous carbon body according to an embodiment of the present invention, 40 to 60% of the total N contained in the porous carbon body may be a quaternary-N bonded state, Of the total S contained in the sieve, 50 to 60% may be in a thiopene-S bonded state.

More particularly, the porous carbon body according to an embodiment of the present invention may have a BET specific surface area of 1000 to 1450 m ² / g, a microporosity of 0.35 to 0.85 cm ³ / g, and a meso porosity of 0.7 to 1.10 cm ³ / g have.

The above-described porous carbon body may be an electrode material or an adsorbent such as a secondary battery, a super capacitor, a solar cell, a sensor, and a condensation desalination unit (CDI). In detail, the porous carbon body may be an anode active material of a secondary battery, an electrode material of a supercapacitor, an electrode material of a solar cell, an electrode material of a CDI or an electrode material of a sensor, or an adsorbent.

The present invention includes a membrane electrode assembly comprising the above-described porous carbon body as a catalyst. The present invention includes a fuel cell comprising the above-described porous carbon body as a catalyst. At this time, the fuel cell may be an alkali fuel cell (AFC), a polymer electrolyte fuel cell (PEMFC), or a direct methanol fuel cell (DMFC). Specifically, the membrane electrode assembly may include an electrode including the above-described porous carbon body as a catalyst and a gas diffusion layer for allowing fuel and air to be uniformly supplied to the electrode. The fuel cell may include an ion conductive electrolyte, A membrane electrode assembly including a carbon body and a bipolar plate disposed on both sides of the membrane electrode assembly and formed with predetermined flow channel channels for supplying fuel and air to both sides thereof.

(Example)

5 g of dried seaweed (Undaria pinnatifida) was pyrolyzed in a nitrogen atmosphere at 800 ° C, 900 ° C, 1000 ° C or 1100 ° C for 5 hours. Thereafter, the product obtained by pyrolysis was immersed in a 3 molar hydrochloric acid aqueous solution for 24 hours, leached, washed with deionized water until the pH became neutral, and dried at 80 DEG C to prepare a porous carbon body Respectively.

In the following drawings and description, 'SCup-X' means a porous carbon body pyrolyzed at the temperature of X and produced by acid leaching treatment, and 'SCupB-X' is pyrolyzed at the temperature of X, Carbon "

1 (a), 1 (b), 1 (b) and 1 (c) show scanning electron microscopic photographs of SCCP- Fig. 1 (d) is a photograph of SCup-800, Fig. 1 (e) is SCup-900, and Fig. 1 (f) is a photograph of SCup-1100 samples. At this time, all the scale bars in Fig. 1 are 5 mu m.

2 (b), 2 (b), 2 (b) and 2 (c) show transmission electron microscope photographs of the porous carbon bodies prepared in Examples, Fig. 2 (d) is a photograph of SCup-800, Fig. 2 (e) is a SCup-900 and Fig. 2 (f) is a photograph of SCup-1100 samples. At this time, all the scale bars in Fig. 2 are 5 nm.

As can be seen from FIGS. 1 and 2, the pyrolysis temperature increases and the surface roughness increases. It can be seen that pore is generated by the acid leaching treatment. In this case, when pyrolysis was performed at 1100 ° C, volatilization of inorganic compounds was observed before the acid leaching, and pores were formed. However, the density and pore volume of the pores decreased by pyrolysis at high temperature. In addition, it can be seen from FIG. 2 that the inorganic compound particles are dispersed in the carbon body through observation images before the acid leaching treatment.

The specific surface area was measured using the BET method, and the microporosity and the meso porosity were measured using an adsorption isotherm of nitrogen at -196 캜 (N ₂ isotherm, Micromeritics ASAP 2020). The results are summarized in Table 1 below, Adsorption isotherm measurement results of the raw materials themselves (Fig. 3 (a)), SCup-800 (Fig. 3 (b)), SCup-900 (Fig. 3 (c)) and SCup- Respectively. At this time, the pore size distribution was calculated using the BJH method.

(Table 1)

As can be seen from Table 1 and FIG. 3, the porosity increases and the specific surface area increases as the pyrolysis temperature increases. However, at the pyrolysis temperature of 1100 ° C, the pore structure collapses and the porosity and specific surface area . ≪ / RTI >

Fig. 4 is a graph showing the results of X-ray diffraction analysis (Fig. 4 (b)) and X-ray diffraction analysis of the product obtained by thermal decomposition before acid leaching treatment (Fig. Fig. As can be seen from FIG. 4, it can be seen that a carbon body containing various inorganic compounds difficult to be analyzed by pick indexing together with halite (NaCl) and magnesium oxide is produced by pyrolysis, And it is confirmed that only the pure layered carbon of the crystal phase is detected.

Table 2 summarizes the X-ray photoelectron spectroscopic (XPS) analysis results of the raw material itself, the product obtained by pyrolysis before acid leaching, and the carbon material produced in the example.

(Table 2)

 It can be seen from Table 2 that inorganic elements including Mg, Na and Cl exist before the acid leaching treatment in accordance with the X-ray diffraction results of FIG. 4 and the transmission electron microscopic observation results of FIG. 2, It can be confirmed that such an inorganic element is removed.

In addition, it can be confirmed that even after pyrolysis and acid leaching, the heterogeneous elements including N, S and O remain in the porous carbon body.

FIG. 5 is a graph showing the relative binding state fractions of N and S contained in a carbon material, according to the XPS analysis results of the porous carbon material prepared in the examples. (Pyrrolic-N, peak: 400.5 eV), N3 is pyrrolic-N (pyrrole-N) Quaternary-type N (peak 401.5 eV), and N4 means pyridine-N-oxide (peak 402 to 405 eV). FIG. 5 (b) shows the fraction of S in the binding state, and C-S-C (2p3 / 2) corresponds to thiopene-S bond.

As can be seen from FIG. 5, it can be seen that as the thermal decomposition temperature varies, the relative ratios of the main bonding states of N and S contained in the carbon body are varied. At the pyrolysis temperature of 1000 to 1100 ° C, The binding ratio of Opfen-S is remarkably increased.

The electrochemical activity of the prepared porous carbon body was measured. 1 mg of the porous carbon material prepared in the Example was put into 1 ml of a mixed solvent (a solvent in which 5% by weight of a naphthenic aqueous solution and water were mixed in a volume ratio of 1: 9) and ultrasonic waves were applied for 20 minutes to prepare a catalyst slurry . For comparison, a catalyst slurry was similarly prepared using a commercially purchased 20 wt% Pt / C catalyst (E-TEK). Then, a catalyst slurry prepared on a working electrode was applied and dried to prepare an electrode (hereinafter referred to as a catalyst electrode) loaded with a catalyst (porous carbon body or 20 wt% Pt / C) at 0.16 μg / cm ² . The electrochemical properties of the prepared catalyst electrode were analyzed by cyclic voltammetry (CV) and linear scan voltammetry (LSV). A rotating ring disk electrode (Model ALS Co., RRDE-3A, 4 mm glassy carbon RRDE working electrode) at room temperature, Pt wire and KCl saturated Ag / AgCl counter electrode and reference electrode, 0.1 M KOH aqueous electrolyte Was used for analysis.

FIG. 6 is a graph showing the result of LSV measurement of a catalyst electrode using a rotating ring-disk electrode, which is a measurement result at a scan speed of 10 mV / s and a rotational speed of 1600 rpm. The results of a 20 wt% Pt / C catalyst sold commercially in FIG. 6 are also plotted on a comparative basis (corresponding to the purple line in FIG. 6, expressed as 20 wt% Pt / C or 20 wt% Pt / VC). Disk current (disk current) in Fig. 6, HO ₂ in Fig. 6, Fig. 6 was shown in (a) (b) ring current (ring current) a, 6 (c) it is also ^in-a production rate, and Fig. 6 (d) Shows the electron mobile number.

FIG. 7 is a graph showing the result of LSV measurement of a catalyst electrode using a rotating ring-disk electrode, which is a result of measurement at a scan rate of 10 mV / s. The rpm shown in Figure 7 is a rotating ring-disc electrode is a rotating speed of, 'N ₂ -saturated' is N ₂ - the results with a saturated aqueous solution of 0.1M KOH, 'O ₂ -saturated' are O ₂ - saturated Fig. 7 (a) shows the result of measurement of a sample manufactured using SCup-800, Fig. 7 (b) shows a result of measurement of a sample manufactured using SCup- 7 (c) is a measurement result of a sample manufactured using SCup-1000, and Fig. 7 (d) is a measurement result of a sample manufactured using SCup-1100.

As can be seen from FIGS. 6 and 7, SCup-900 or SCup-1000 is similar to commercially available Pt / C catalysts with an onset potential of ORR (Ox Reduction Reaction) -1000, the Pt / C catalyst almost coincided with the onset potential of -0.01 V, which is superior to the Pt / C catalyst and has an excellent oxygen reduction activity. This can be interpreted as a result of the relatively high specific surface area as well as the relatively high content of quaternary-N, pyridinic-N and thiophen-S providing the active site of the oxygen reduction reaction have.

8 is a graph showing the CV measurement result of the catalyst electrode using the rotating ring-disk electrode, which is a measurement result at a scan speed of 50 mV / s. 'N ₂ -saturated' in Fig. 8 N ₂ - the results with a saturated aqueous solution of 0.1M KOH, 'O ₂ -saturated' are O ₂ - the results with a saturated aqueous solution of 0.1M KOH, 'O ₂ -saturated in 3M CH ₃ OH 'means a result using an O ₂ -saturated 0.1 M KOH aqueous solution containing 3M CH ₃ OH. 8 (a) shows the results of measurement of the catalyst electrode prepared using Scup-1000, and FIG. 8 (b) shows the measurement results of the catalyst electrode prepared using commercially available 20 wt% Pt / FIG. 8 (c) is a graph showing the relative current density-time at the maximum current of the oxygen reduction reaction forward peak in the O ₂ -saturated condition for each of the catalyst electrode of Scup-1000 and the catalyst electrode of 20 wt% Pt / Fig.

FIG. 9 is a graph showing a CV measurement result of a catalyst electrode using a rotating ring-disk electrode, which is a measurement result at a scan rate of 50 mV / s. Figure 'N ₂ -saturated' in the 9 N ₂ - the results with a saturated aqueous solution of 0.1M KOH, 'O ₂ -saturated' are O ₂ - means a result with a saturated aqueous solution of 0.1M KOH, 9 ( Fig. 9 (b) shows the measurement results of the catalyst electrode manufactured using SCup-900, Fig. 9 (c) shows the results of measurement using the SCup-1100 Fig. 9 (d) shows the measurement results of the catalyst electrodes manufactured using SCup-1000 together with the measurement results of Figs. 9 (a) to 9 (c) FIG.

8 and 9, when the N ₂ -saturated 0.1 M KOH aqueous solution was used, both of the porous carbon body and the 20 wt% Pt / C catalyst prepared in the examples were characterized in the range of -1.2 to +0.3 V A voltammetric current was not observed, and a characteristic cathodic peak current was observed by the oxygen reduction reaction when an O ₂ -saturated aqueous solution was used. As can be seen from FIG. 8, in the case of the catalyst electrode prepared using SCup-1000, it was found that a caustic peak current was generated near -0.12 V, similar to the catalyst electrode prepared using 20 wt% Pt / C catalyst And the peak generation position shifts according to the pyrolysis temperature.

Also, as can be seen from FIG. 8, it can be seen that a very large methanol oxidation peak occurs at -0.27 V and -0.16 V in the case of the 20 wt% Pt / C catalyst, It can be seen that the peak due to the photoluminescence disappears completely. However, in the case of the porous carbon material prepared in the examples including SCup-1000, it can be seen that the selectivity of the oxygen reduction reaction is excellent even in the presence of methanol, which is very stable with respect to methanol.

FIG. 8 (c) shows the long-term stability of the catalyst in an alkaline medium. As a result, it can be seen that, in the case of 20 wt% Pt / C catalyst, a current reduction of 75.4% , And SCup-1000, the current of 73.2% is maintained even at 30,000 sec in the case of the porous carbon body manufactured in the examples. As a result, it can be seen that the porous carbon material prepared in the examples has very excellent durability.

To evaluate the electrical characteristics of the prepared porous carbon body, a device similar to that shown in Fig. 10 (a) was used. Specifically, the porous carbon bodies prepared in Examples were charged into a Teflon cylinder (cross-sectional area of 0.126 cm ² ), and a current was supplied through metal pistons at both ends while being pressurized using a brass piston located at both ends of the cylinder And the voltage was measured through a pair of voltage leads (0.2 cm between the voltage leads) contacting the multi-core carbon body inside the cylinder through the side of the cylinder, and the electrical characteristics according to the pressure were measured. At this time, for comparison, graphite was added in place of the porous carbon material prepared in the examples, and the measurement was carried out under the same conditions. FIG. 10 (b) is a graph showing the resistivity measured according to the pressure of the porous carbon body manufactured in the embodiment, and FIG. 10 (c) is an enlarged view of a part of FIG. 10 (b).

As can be seen from FIG. 10, it can be seen that as the pressure increases and the pyrolysis temperature increases, the resistivity decreases. In the case of the porous carbon material produced at the pyrolysis temperature of 900 to 1100 ° C., , It is found that it has excellent electric conduction characteristics as compared with the conventional activated carbon bodies having porosity.

11 shows the conductivity, the mesophore specific surface area, the nitrogen content in the heterogeneous element, and the onset potential obtained from the measurement results of FIG. 10 of the porous carbon body prepared in the examples with different thermal decomposition temperatures.

As described above, the present invention has been described with reference to specific embodiments, limited examples, and drawings. However, it should be understood that the present invention is not limited to the above-described embodiments, Various modifications and variations may be made thereto by those skilled in the art.

Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

Claims (14)

a) pyrolyzing seaweed in an inert atmosphere to produce an inorganic-carbon body having carbon atoms containing inorganic compound particles; And
and b) leaching the inorganic compound particles of the inorganic-carbon substance by acid leaching to remove the inorganic compound particles. The method according to claim 1,
Wherein the heterogeneous element originates from the seaweed, and comprises at least N and S. 3. The method of claim 2,
Wherein the thermal decomposition temperature is controlled to control a relative ratio of the bonded states of the hetero elements. The method according to claim 1,
Wherein the inorganic compound comprises at least a metal halide, a metal oxide, or a mixture thereof. The method according to claim 1,
Wherein the porous carbon body has a turbostratic structure. The method according to claim 1,
Wherein the pyrolysis temperature in step (a) is 800 to 1100 ° C. The method of claim 3,
Wherein 15 to 60% of the N is in a quaternary-N bonded state, 20 to 40% is in a pyridinic N bonded state, and 35 to 60% of the S is substituted by thiopene -S) bonded state. 3. The method of claim 2,
Wherein the content of N and S is 3 to 6.5% by mass. The method according to claim 6,
Wherein the porous carbon body has a BET specific surface area of 650 to 1450 m ² / g, a microporosity of 0.2 to 0.85 cm ³ / g, and a meso porosity of 0.2 to 1.10 cm ³ / g. The method according to claim 1,
Wherein the porous carbon body is a catalyst for a fuel cell. A porous carbon body having a turbostratic structure prepared by pyrolysis of marine algae followed by acid leaching treatment. The porous carbon body has a BET specific surface area of 650 to 1450 m ² / g, a microporosity of 0.2 to 0.85 cm ³ / g, 1.10 cm < ³ > / g, and contains at least N and S. The porous carbon body contains a heterogeneous element. 12. The method of claim 11,
Wherein 15 to 60% of the N is in a quaternary-N bonded state, 20 to 40% is in a pyridinic N bonded state, and 35 to 60% of the S is substituted by thiopene -S) -bonded heterogeneous element. 13. The method of claim 12,
Wherein the porous carbon body has a BET specific surface area of 1000 to 1450 m ² / g. 11. A fuel cell comprising the porous carbon body according to claim 11 as a catalyst of an electrode.

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