KR102219873B1 - Manufacturing Method of Graphene Coated Carbon Ultra-Thin Film and Graphene Coated Carbon Ultra-Thin film by same the method - Google Patents

Abstract

An embodiment of the present invention provides a method of manufacturing graphene coated with an ultrathin carbon film including mesopores and micropores, and graphene coated with an ultrathin carbon film prepared by the method.

Description

Manufacturing method of graphene coated with an ultra-thin carbon film and graphene coated with an ultra-thin carbon film produced by the method {Manufacturing Method of Graphene Coated Carbon Ultra-Thin Film and Graphene Coated Carbon Ultra-Thin film by same the method}

The present invention relates to a method for producing graphene coated with an ultra-thin carbon film and to graphene coated with an ultra-thin carbon film prepared by the method, and more particularly, to a graphene coated with an ultra-thin carbon film including meso and micro-sized pores. It relates to a method of manufacturing a pin and graphene coated with an ultra-thin carbon film manufactured by the method.

Graphene is a honeycomb-shaped two-dimensional planar carbon allotrope composed of sp2 bonds of carbon atoms. Of the four outermost electrons in the carbon atom, three electrons form a σ-bond to form a hexagonal structure, and a long range of π-conjugated structures formed by the remaining one electron (as π, graphene is It moves freely and has excellent physical and electrical properties Graphene has more than 100 times higher electron mobility than silicon, which is the main raw material for semiconductor materials, and more than 100 times more electrical conductivity than copper, and has a tensile strength of more than 200 times that of steel. The electrical conductivity does not decrease even if the area is stretched or bent more than 10% because of its high elasticity, and it has more than twice the thermal conductivity of diamond, which has the highest thermal conductivity among existing materials.

Using these physicochemical properties, it is also applied as a protective coating agent in various fields such as fuel cells, transparent electrodes, next-generation semiconductors, ultra-light materials, seawater desalination, and protection of metals and alloys in organic solar cells. Can be used as

The requirements for fuel cell catalysts require high reactivity and surface area, and a simplified manufacturing method and price competitiveness are required. Platinum was used as the most excellent material among catalysts for fuel cells, but it is experiencing great difficulty in commercialization due to price issues. Accordingly, there is a need for an excellent performance and low cost catalyst that can replace platinum.

As an alternative to this, organic material-based catalysts have been steadily developed, but there is a problem in that the synthesis process is long and complicated, so that an increase in price is inevitable, or a large amount of catalyst has to be used due to low performance. To compensate for this, we attempted to develop a material that is simple to synthesize, has a reasonable price, and has excellent performance even with a small amount of catalyst.

KR No. 2017-0116842

The technical problem to be achieved by the present invention is to provide a method for producing graphene coated with an ultra-thin carbon film that can reduce the production cost without complicating the synthesis process.

In addition, it is to provide a graphene coated with an ultra-thin carbon film, which is manufactured by the method and has excellent catalytic performance.

The technical problem to be achieved by the present invention is not limited to the technical problems mentioned above, and other technical problems that are not mentioned can be clearly understood by those of ordinary skill in the technical field to which the present invention belongs from the following description. There will be.

In order to achieve the above technical problem, an embodiment of the present invention is to prepare an organic material solution containing a nano-sized polymer urea gel, by mixing and reacting the graphene oxide in the organic material solution to the polymer urea on the surface of the graphene oxide. Forming a gel layer, reducing the graphene oxide to form graphene coated with a polymer urea gel layer, forming mesopores in the polymer urea gel layer by primary heat treatment of graphene coated with the polymer urea gel layer It provides a method of producing graphene coated with an ultra-thin carbon film, comprising: forming an ultra-thin carbon film by carbonizing the polymeric urea gel layer by secondary heat treatment of the graphene coated with the polymer urea gel layer.

In addition, the nano-sized polymer urea gel may be characterized in that the surface is surrounded by amine or isocyanate functional groups.

In addition, the first heat treatment temperature may be characterized in that 230 ℃ to 400 ℃.

In addition, the secondary heat treatment temperature may be characterized in that 600 ℃ to 1000 ℃.

In addition, in the step of forming the ultrathin carbon film, micropores may be formed in the ultrathin carbon film as the polymeric urea gel layer is carbonized.

In addition, in the step of forming graphene coated with the polymer urea gel layer, graphene may be 5 wt% to 40 wt% based on the total weight of graphene coated with the polymer urea gel layer.

In addition, in the step of forming the ultra-thin carbon film, a ratio of graphene to the total weight of graphene coated with the ultra-thin carbon film may be 10 wt% to 50 wt%.

In addition, in order to achieve the above technical problem, an embodiment of the present invention includes graphene and a carbon ultra-thin film coated on the graphene surface, and mesopores and micropores are formed inside the carbon ultra-thin film. Provides ultra-thin coated graphene.

In addition, the graphene coated with the ultra-thin carbon film is characterized in that it contains 2wt% to 10wt% nitrogen.

In addition, it may be characterized in that it contains pyridine or pyrrole in the graphene coated with the ultra-thin carbon film.

In addition, the thickness of the ultra-thin carbon film may be characterized in that 10 nm or less.

In addition, the ultra-thin carbon film may be coated on one or both sides of the graphene.

In addition, the total surface area of the pores including the micropores and mesopores may be 50 ㎡/g to 1000 ㎡/g.

In addition, the graphene coated with the ultra-thin carbon film may be characterized by having excellent oxygen adsorption properties.

According to an exemplary embodiment of the present invention, since the ultra-thin carbon film coated on the surface of graphene has mesopores and micropores, it has a large surface area and excellent oxygen adsorption by opening a large amount of active sites.

In addition, even though it is an organic material-based catalyst that is cheaper than platinum, it is possible to manufacture a catalyst having as high a reduction property and reactivity as this.

In addition, it is possible to reduce the manufacturing cost by proceeding the process for forming the carbon layer as a solution process.

It is cheaper than platinum, but has higher safety and current density, so it is possible to manufacture and utilize a catalyst suitable for commercialization.

The effects of the present invention are not limited to the above effects, and should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description or claims of the present invention.

1 is a conceptual diagram according to a manufacturing sequence of a method of manufacturing graphene coated with an ultra-thin carbon film according to an embodiment of the present invention.
2 is an SEM photograph showing the thickness of the ultra-thin carbon film of graphene coated with the ultra-thin carbon film according to an embodiment of the present invention.
3 is a SEM photograph showing the shape of graphene to which a polymer urea gel is attached and graphene coated with an ultra-thin carbon film according to an embodiment of the present invention.
4 is an XPS analysis graph of graphene coated with an ultra-thin carbon film according to an embodiment of the present invention.
5 is a BET graph for analyzing specific surface areas of graphene oxide, graphene coated with a polymer urea gel layer, and graphene coated with an ultra-thin carbon film according to an embodiment of the present invention.
6 is a graph analyzing the pore dispersion of reduced graphene oxide, polymer urea gel, graphene coated with a polymer urea gel layer, and graphene coated with an ultra-thin carbon film according to an embodiment of the present invention.
7 is a graph for confirming the mesopores and micropore dispersion of graphene coated with an ultra-thin carbon film (Preparation Examples 1 to 4) according to an embodiment of the present invention.
8 is a graph showing oxygen adsorption performance characteristics of Pt/C and graphene coated with an ultra-thin carbon film according to an embodiment of the present invention (Preparation Examples 1 to 4).
9 is a graph showing the electrical conductivity of graphene coated with an ultra-thin carbon film (Preparation Examples 1 to 4) according to an embodiment of the present invention.
10 is a graph analyzing the catalytic activity characteristics of Pt/C and graphene coated with an ultra-thin carbon film according to an embodiment of the present invention (Preparation Examples 1 to 4).
11 is a graph analyzing the number of electron transfers of graphene (Preparation Examples 1 to 4) coated with Pt/C and an ultra-thin carbon film according to an embodiment of the present invention.
12 is a graph comparing ethanol resistance of Preparation Example 3 showing the best properties among graphene coated with Pt/C and an ultra-thin carbon film according to an embodiment of the present invention.
13 is a graph analyzing the life characteristics of Preparation Example 3 showing the best characteristics among graphene coated with Pt/C and an ultra-thin carbon film according to an embodiment of the present invention.

Hereinafter, the present invention will be described with reference to the accompanying drawings. However, the present invention may be implemented in various different forms, and therefore is not limited to the embodiments described herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and similar reference numerals are assigned to similar parts throughout the specification.

Throughout the specification, when a part is said to be "connected (connected, contacted, bonded)" with another part, it is not only "directly connected", but also "indirectly connected" with another member in the middle. "Including the case. In addition, when a part "includes" a certain component, it means that other components may be further provided, rather than excluding other components unless specifically stated to the contrary.

The terms used in the present specification are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or a combination thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance.

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

Nanoporous materials are materials having a certain porous structure, and generally refer to materials in the form of powders, thin films/thick films, and bulk materials that are arranged in a size of 0.4 to 100 nm or composed of disordered pore structures. Therefore, in order to describe the method of manufacturing graphene coated with an ultra-thin carbon film and graphene coated with an ultra-thin carbon film according to the present invention, the pore size of the ultra-thin carbon film, which is a nanoporous material, is distinguished to refer to the term.

As used herein, the terms micro and mesopores are terms used to distinguish nano-sized pore sizes, and it can be understood that the term is a term for dividing pore sizes by size. Here, micro pores having a diameter of 2 nm or less, meso pores having a diameter of 2 nm to 50 nm, and pores having a diameter of 50 nm or more refer to macro pores.

In addition, for clarity, terms used in the specification may be abbreviated as follows. Graphene oxide (GO), high molecular weight urea gel (Urea Network; UN), high molecular weight urea gel layer coated graphene (Urea Network Coated Graphene; UNG), carbon ultra thin film coated graphene (Pyrolyzed Urea Network Carbon) film Graphene; PUNG), etc.

A method of manufacturing the graphene 31 coated with the ultrathin carbon film 50 according to an embodiment of the present invention will be described.

1 is a conceptual diagram according to a manufacturing sequence of a method of manufacturing a graphene 31 coated with an ultra-thin carbon film 50 according to an embodiment of the present invention.

Referring to FIG. 1, the method of manufacturing graphene 31 coated with an ultra-thin carbon film 50 includes preparing an organic material solution 20 containing a nano-sized polymer urea gel 10, the organic material solution 20 ) Forming a polymer urea gel layer 40 on the surface of the graphene oxide 30 by mixing and reacting the graphene oxide 30, the polymer urea gel layer 40 is coated by reducing the graphene oxide 30 Forming the graphene 31, forming the mesopores 41 in the polymer urea gel layer 40 by primary heat treatment of the graphene 31 coated with the polymer urea gel layer 40, and the Secondary heat treatment of the graphene 31 coated with the polymer urea gel layer 40 may include forming an ultra-thin carbon film 50 in which micropores 51 are formed by carbonization of the polymer urea gel layer 40 .

Referring to the first step a of FIG. 1, an organic material solution 20 including a nano-sized polymer urea gel 10 is prepared.

At this time, the polymer urea gel 10 is a nano-sized polymer gel having a molecular network in which Tetrakis (4-aminophenyl) methane (TAPM) and Hexamethylene diisocyanate (HDI) are connected to a urea functional group in a solution state. .

Polymer urea gel (10) (UN) is a form in which the surface is surrounded by amine or isocyanate functional groups.

The polymer urea gel 10 is dissolved in the solution to prepare an organic material solution 20 uniformly present.

Next, referring to b of FIG. 1, graphene oxide 30 is added to the organic material solution 20. At this time, the graphene oxide 30 is mixed and reacted with the organic material solution 20 in which the nano-sized polymer urea gel 10 is dispersed, and the surface functional groups of the polymer urea gel 10 and the surface functional groups of the graphene oxide 30 The polymer urea gel 10 is evenly spread and adhered to the surface of the graphene oxide 30 through a covalent bond. Through such a solution process, a polymer urea gel layer 40 may be formed on the surface of the graphene oxide 30.

Thereafter, the graphene oxide 30 on which the polymer urea gel layer 40 is formed may be reduced to form the graphene 31 coated with the polymer urea gel layer 40.

At this time, the graphene 31 may be characterized in that 5wt% to 40wt% relative to the total weight of the graphene 31 coated with the polymer urea gel layer 40.

When prepared in such a ratio, it may be in a state optimized for the oxygen adsorption performance of the graphene 31 coated with a carbon ultra-thin film according to the present invention to be described below.

Next, referring to FIG. 1C, the graphene 31 coated with the polymer urea gel layer 40 is first heat-treated to form mesopores 41 in the polymer urea gel layer 40.

In this case, the first heat treatment temperature may be 230° C. to 400° C. or higher, and the mesopores 41 formed through the first heat treatment may be formed by disposing an alkyl chain included in the polymer urea gel 10.

The description of the formation of the mesopores 41 of the present invention will be described with reference to Scheme 1 and Scheme 2 below.

Here, R in the reaction formula means an organic group having 1 to 100 carbon atoms.

[Scheme 1]

[Scheme 2]

The urea group can be decomposed through heat treatment of the porous polyurea body to produce an amine compound and an isocyanate compound. An appropriate heat treatment temperature for decomposition may be 230° C. to 400° C., but is not limited thereto. Such a decomposition mechanism can be expressed by Scheme 1.

In more detail, the urea group in the porous polyurea material, which may be expressed as in Scheme 1(a), may be decomposed into various forms as in Scheme 1(b). The part that is decomposed and removed here is a part containing _{R 2 which is relatively light and volatile.}

As described above, the isocyanate compound generated through decomposition of the porous polyurea body may be heat-treated and rearranged, thereby forming a crosslinked structure with an isocyanurate bond. The reaction for forming such a crosslinked structure can be expressed by Scheme 2. That is, reactions such as dicyclic and tricyclic between isocyanate compounds generated through decomposition occur to form a new crosslinked structure containing an isocyanurate bond that is stable to heat, so that the isocyanurate polymer repeats the cyclic compound. It can form a connected annular structure, and can form a three-dimensional network. In addition, the decomposition and rearrangement occur not only inside the polyurea network, but also outside the network, so that the overall structure is a single entity, resulting in a thermal rearrangement of organic molecular networks (Rearranged urea Molecular Networks).

The heat treatment temperature for the rearrangement is preferably 230°C to 400°C.

Next, referring to FIG. 1D, the graphene 31 coated with the polymer urea gel layer 40 is subjected to secondary heat treatment to carbonize the polymer urea gel layer 40 to form an ultra-thin carbon film ( 50).

Here, the secondary heat treatment temperature is raised to 600° C. or higher to carbonize the polymer urea gel layer 40.

In this process, as the polymer urea gel layer 40 is carbonized, micropores 51 may be formed in the ultra-thin carbon film 50. In addition, the polymer urea gel 10 covalently connected to the surface of the graphene 31 is not aggregated or separated and is fixed to the surface of the graphene 31. In addition, it is possible to form an ultra-thin carbon film 50 containing micro- and mesopores 41 on the surface of the graphene 31 due to the evaporated organic matter.

The micropores 51 develop pores similar to the principle of formation of the mesopores 41, but the pores on the surface of the urea gel react for a long time to form mesopores 41 with a relatively large diameter. The gel has a short reaction time, so small pores can be formed. In addition, micropores 51 are generated due to grapheneization occurring in the carbonization process.

In addition, the total surface area of the pores including the micropores 51 and mesopores 41 may range from 50 ㎡/g to 1000 ㎡/g.

Accordingly, the graphene 31 coated with the ultra-thin carbon film 50 may be characterized by having excellent oxygen adsorption properties.

The graphene 31 coated with the ultrathin carbon film 50 thus formed is referred to as (Pyrolyzed Urea Network Carbon film Graphene; PUNG).

At this time, the ratio of the graphene 31 to the total weight of the graphene 31 coated with the ultrathin carbon film 50 may be 10wt% to 50wt%.

When prepared in the above ratio, the pore characteristics can be optimized, and thus, oxygen adsorption performance can be obtained with a large surface area.

In addition, the ultra-thin carbon film 50 may be characterized in that it contains nitrogen. For example, such nitrogen may be included in the ultra-thin carbon film 50 or graphene 31.

The content of the nitrogen element contained in the graphene 31 coated with the ultra-thin carbon film 50 may be 2 wt% to 10 wt%.

In addition, pyridine or pyrrole may be included in the graphene 31 coated with the ultra-thin carbon film 50. Referring to FIG. 4 to be described later, it can be seen that the nitrogen contained in the graphene 31 coated with the ultrathin carbon film 50 is present in the form of pyridine or pyrrole.

The graphene 31 (PUNG) coated with the ultra-thin carbon film 50 according to an embodiment of the present invention will be described.

At this time, the graphene 31 (PUNG) coated with the ultrathin carbon film 50 according to an embodiment of the present invention will be described with reference to d of FIG. 1.

The configuration of the graphene 31 (PUNG) coated with the ultrathin carbon film 50 includes graphene 31 and the ultrathin carbon film 50 coated on the surface of the graphene 31, and the ultrathin carbon film 50 Mesopores 41 and micropores 51 may be formed therein.

The carbon ultra-thin film 50 coated on the surface of the graphene 31 is bonded by covalent bonding between the polymer urea gel 10 and the graphene 31 as described in the above manufacturing technology, and then graphene due to the evaporated organic matter. The surface of (31) may be coated with a nano-sized thin carbon ultra-thin film (50).

At this time, the thickness of the ultra-thin carbon film 50 is 10 nm or less. For example, the thickness of the ultra-thin carbon film 50 may be 1 nm to 10 nm.

In addition, the ultra-thin carbon film 50 may be characterized in that it contains nitrogen. For example, such nitrogen may be included in the ultra-thin carbon film 50 or graphene 31.

The content of the nitrogen element contained in the graphene 31 coated with the ultra-thin carbon film 50 may be 2 wt% to 10 wt%.

In addition, pyridine or pyrrole may be included in the graphene 31 coated with the ultra-thin carbon film 50. Referring to FIG. 4 to be described later, it can be seen that the nitrogen contained in the graphene 31 coated with the ultrathin carbon film 50 is present in the form of pyridine or pyrrole.

The ultra-thin carbon film 50 may be coated on one or both surfaces of the graphene 31.

The total surface area of the pores including the micropores 51 and mesopores 41 is characterized in that 50 ㎡/g to 1000 ㎡/g.

In addition, the graphene coated with the ultra-thin carbon film 50 may be characterized by having excellent oxygen adsorption properties.

The following preparation examples were compared with a platinum-carbon (Pt/C) catalyst used as a commercial fuel cell catalyst.

As shown in Table 1 to be described later, the surface area of Pt/C is 161 m 2 /g, the surface area of the mesopores 41 is 61 m 2 /g, and the surface area of the micropores 51 is 100 m 2 /g.

Manufacturing Example 1 ( PUNG -One)

A step of preparing an organic material solution 20 including the nano-sized polymer urea gel 10 is performed.

Next, a step of forming a polymer urea gel layer 40 on the surface of the graphene oxide 30 by mixing and reacting the graphene oxide 30 in the organic material solution 20 is performed.

Thereafter, the step of forming the graphene 31 coated with the polymer urea gel layer 40 by reducing the graphene oxide 30 is performed.

At this time, the ratio of the weight of the graphene 31 to the total weight of the graphene 31 coated with the polymer urea gel layer 40 was 7.6 wt%.

Thereafter, the first heat treatment of the graphene 31 coated with the polymer urea gel layer 40 is performed to form pores 41 in the polymer urea gel layer 40.

Here, the first heat treatment temperature was carried out while raising the temperature at 230°C to 400°C. In the process of performing the heat treatment, the alkyl chains contained in the molecular network of the polymer urea gel 10 disappear and pores are formed. At this time, the pores may be mainly meso-sized pores.

Finally, a step of forming the ultra-thin carbon film 50 by carbonizing the polymer urea gel layer 40 by secondary heat treatment of the graphene 31 coated with the polymer urea gel layer 40 is performed.

At this time, the secondary heat treatment temperature was performed by raising the temperature to 600°C or higher, and as the polymer urea gel layer 40 is carbonized, the organic matter is not completely evaporated but is fixed on the surface of the graphene 31, and an ultrathin carbon film 50 is formed. .

In addition, pores are formed while being carbonized, and micropores 51 may be formed as pores at this time.

At this time, the ratio of the weight of the graphene 31 to the total weight of the graphene 31 coated with the ultrathin carbon film 50 was 20wt%.

The surface area of the mesopores 41 formed after the first heat treatment is 39 ㎡/g, and the surface area of the micropores 51 formed after the second heat treatment is 170 ㎡/g, and the surface area of the total pores is 209 ㎡/g.

Manufacturing example 2( PUNG -2)

A step of preparing an organic material solution 20 including the nano-sized polymer urea gel 10 is performed.

Next, a step of forming a polymer urea gel layer 40 on the surface of the graphene oxide 30 by mixing and reacting the graphene oxide 30 in the organic material solution 20 is performed.

Thereafter, the step of forming the graphene 31 coated with the polymer urea gel layer 40 by reducing the graphene oxide 30 is performed.

At this time, the ratio of the weight of the graphene 31 to the total weight of the graphene 31 coated with the polymer urea gel layer 40 was 14.2 wt%.

Thereafter, a step of forming the mesopores 41 in the polymer urea gel layer 40 by first heat treatment of the graphene 31 coated with the polymer urea gel layer 40 is performed.

Here, the first heat treatment was performed while raising the temperature at 230°C to 400°C, and in the process of performing the heat treatment, the alkyl chains contained in the molecular network of the polymer urea gel 10 disappear and pores are formed. At this time, the pores may be meso-sized pores.

Finally, a step of forming the ultra-thin carbon film 50 by carbonizing the polymer urea gel layer 40 by secondary heat treatment of the graphene 31 coated with the polymer urea gel layer 40 is performed.

At this time, the secondary heat treatment temperature was performed by raising the temperature to 600°C or higher, and as the polymer urea gel layer 40 is carbonized, the organic matter is not completely evaporated but is fixed on the surface of the graphene 31, and an ultrathin carbon film 50 is formed. .

In addition, pores are formed while being carbonized, and the pores at this time may be micro-sized pores.

At this time, the ratio of the weight of the graphene 31 to the total weight of the graphene 31 coated with the ultrathin carbon film 50 was 33wt%.

The surface area of the mesopores 41 formed after the first heat treatment is 27 ㎡/g, and the surface area of the micropores 51 formed after the second heat treatment is 236㎡/g, and the surface area of the total pores is 263㎡/g.

Manufacturing example 3( PUNG -3)

A step of preparing an organic material solution 20 including the nano-sized polymer urea gel 10 is performed.

Next, a step of forming a polymer urea gel layer 40 on the surface of the graphene oxide 30 by mixing and reacting the graphene oxide 30 in the organic material solution 20 is performed.

Thereafter, the step of forming the graphene 31 coated with the polymer urea gel layer 40 by reducing the graphene oxide 30 is performed.

At this time, the ratio of the weight of the graphene 31 to the total weight of the graphene 31 coated with the polymer urea gel layer 40 was 20wt%.

Thereafter, a step of forming the mesopores 41 in the polymer urea gel layer 40 by first heat treatment of the graphene 31 coated with the polymer urea gel layer 40 is performed.

Here, the first heat treatment was performed by raising the temperature at 230°C to 400°C, and in the process of performing the heat treatment, the alkyl chains contained in the molecular network of the polymer urea gel 10 disappear and pores are formed. At this time, the pores may be meso-sized pores.

Finally, a step of forming the ultra-thin carbon film 50 by carbonizing the polymer urea gel layer 40 by secondary heat treatment of the graphene 31 coated with the polymer urea gel layer 40 is performed.

At this time, the secondary heat treatment temperature was performed by raising the temperature to 600°C or higher, and as the polymer urea gel layer 40 is carbonized, the organic matter is not completely evaporated but is fixed on the surface of the graphene 31, and an ultrathin carbon film 50 is formed. .

In addition, pores are formed while being carbonized, and the pores at this time may be micro-sized pores.

At this time, the ratio of the weight of the graphene 31 to the total weight of the graphene 31 coated with the ultrathin carbon film 50 was 43wt%.

The surface area of the mesopores 41 formed after the first heat treatment is 106㎡/g, and the surface area of the micropores 51 formed after the second heat treatment is 300㎡/g, and the surface area of the total pores is 406㎡/g.

Manufacturing example 4( PUNG -4)

A step of preparing an organic material solution 20 including the nano-sized polymer urea gel 10 is performed.

Next, a step of forming a polymer urea gel layer 40 on the surface of the graphene oxide 30 by mixing and reacting the graphene oxide 30 in the organic material solution 20 is performed.

Thereafter, the step of forming the graphene 31 coated with the polymer urea gel layer 40 by reducing the graphene oxide 30 is performed.

At this time, the ratio of the weight of the graphene 31 to the total weight of the graphene 31 coated with the polymer urea gel layer 40 was 25 wt%.

Thereafter, a step of forming the mesopores 41 in the polymer urea gel layer 40 by first heat treatment of the graphene 31 coated with the polymer urea gel layer 40 is performed.

Here, the first heat treatment temperature was carried out while raising the temperature at 230°C to 400°C. In the process of performing the heat treatment, the alkyl chains contained in the molecular network of the polymer urea gel 10 disappear and pores are formed. At this time, the pores may be meso-sized pores.

Finally, a step of forming the ultra-thin carbon film 50 by carbonizing the polymer urea gel layer 40 by secondary heat treatment of the graphene 31 coated with the polymer urea gel layer 40 is performed.

At this time, the secondary heat treatment temperature was performed by raising the temperature to 600°C or higher, and as the polymer urea gel layer 40 is carbonized, the organic matter is not completely evaporated but is fixed on the surface of the graphene 31, and an ultrathin carbon film 50 is formed. .

In addition, pores are formed while being carbonized, and the pores at this time may be micro-sized pores.

At this time, the ratio of the weight of the graphene 31 to the total weight of the graphene 31 coated with the ultrathin carbon film 50 was 50wt%.

The surface area of the mesopores 41 formed after the first heat treatment is 30 ㎡/g, and the surface area of the micropores 51 formed after the second heat treatment is 68㎡/g, and the surface area of the total pores is 98㎡/g.

Experimental example

2 is an SEM photograph showing the thickness of the ultra-thin carbon film 50 of the graphene 31 coated with the ultra-thin carbon film 50 according to an embodiment of the present invention.

Here, referring to FIG. 2, it can be confirmed that the thickness of the ultrathin carbon film 50 is about 4 or 5 nanometers by observing the portion where the graphene 31 is folded.

The organic matter on the surface of the graphene 31 is carbonized through carbonization treatment, which is a secondary heat treatment, which is the last step of the method for producing the graphene 31 coated with the ultra-thin carbon film 50 according to an embodiment of the present invention. A thin ultra-thin film can be formed.

3 is an SEM photograph showing the shape of the graphene 31 coated with the polymer urea gel 10 and the graphene 31 coated with the ultra-thin carbon film 50 according to an embodiment of the present invention.

3, when comparing GO and UNG-3, it was confirmed that UNG, which is graphene 31 coated on the organic material solution 20 containing the polymer urea gel 10, has polymer particles on its surface. I can.

In addition, in the photograph of Preparation Example 3 (PUNG-3) carbonized by the secondary heat treatment, it can be seen that the porous carbon hills are thin and evenly dispersed.

4 is an XPS analysis graph of graphene 31 coated with an ultra-thin carbon film 50 according to an embodiment of the present invention.

Referring to FIG. 4, it can be confirmed that a peak corresponding to the nitrogen atom of pyridine or pyrrole appears through XPS analysis. Accordingly, it can be seen that the graphene 31 (PUNG) coated with the ultra-thin carbon film 50 is doped with appropriate nitrogen.

5 is a graphene oxide 30 according to an embodiment of the present invention, graphene 31 coated with a high molecular weight urea gel layer 40, and graphene 31 coated with an ultrathin carbon film 50 BET It is a graph.

At this time, adsorption and desorption of nitrogen were used in the experiment to confirm the surface area.

Referring to FIG. 5, the graphene oxide 30 (rGO) has a surface area of 274 ㎡/g, a polymer urea gel layer 40 coated graphene 31 (UNG-3) is 44 ㎡/g, and carbon The surface area of the graphene 31 (Preparation Example 3) coated with the ultra-thin film 50 was 406 ㎡/g, and the total surface area of the pores was the largest among Preparation Examples 1 (PUNG-1) to 4 (PUNG-4). You can check it.

Therefore, it can be assumed that the adsorption and desorption of the graphene 31 (PUNG) coated with the ultra-thin carbon film 50 is further performed, and the oxygen adsorption performance is excellent.

6 is a graphene 31 coated with a reduced graphene oxide 30, a polymer urea gel 10, a polymer urea gel layer 40, and an ultra-thin carbon film 50 according to an embodiment of the present invention. It is a graph analyzing the pore dispersion degree of the graphene 31.

Referring to FIG. 6, UNG appears different from the degree of pore dispersion in rGO and has mesopores 41 similar to UN.

Through this, the graphene 31 (PUNG) coated with the ultrathin carbon film 50 has a pore diameter of 0.4 nm to 5 nm, and a large amount of mesopores 41 and micropores 51 are generated. It can be confirmed that it is distributed. A large amount of mesopores 41 and micropores 51 are formed to increase the surface area, thereby exhibiting high oxygen adsorption performance.

The graphene 31 (PUNG) coated with the ultra-thin carbon film 50 was prepared in Preparation Examples 1 (PUNG-1) to 4 (PUNG-4) according to the weight ratio of the graphene 31 to the total weight of the PUNG. ).

7 is a graphene 31 (Preparation Examples 1 to 4) coated with an ultra-thin carbon film 50 according to an embodiment of the present invention to confirm the dispersibility of the mesopores 41 and micropores 51 It can be a graph.

In addition, FIG. 8 is a graph showing oxygen adsorption performance characteristics of graphene 31 (Preparation Examples 1 to 4) coated with Pt/C and an ultra-thin carbon film 50 according to an embodiment of the present invention.

7 and 8, PUNG-3 is distributed into mesopores 41 and micropores 51, and has higher oxygen adsorption than Pt/C, and Preparation Examples 1 (PUNG-1) to 4 Among (PUNG-4), it can be confirmed that the oxygen adsorption performance is the most excellent.

Table 1 below is a table comparing Comparative Examples (Pt/C) and Preparation Examples. In Preparation Examples 1 to 4, the mesopores 41 and micro pores according to the mixing ratio of graphene 31 to the total weight of PUNG It is a table to confirm the ratio of pores (51).

Material Surface area (㎡/g) Mesopore surface area (㎡/g) Micropore surface area (㎡/g) Pt/C 161 61 100 PUNG-1 209 39 170 PUNG-2 263 27 236 PUNG-3 406 106 300 PUNG-4 98 30 68

7, 8 and Table 1, in Preparation Example 2 ((PUNG-2) to Preparation Example 4 (PUNG-4), smooth oxygen adsorption may be exhibited.

Preparation Example 2 (PUNG-2) and Preparation Example 3 (PUNG-3) may have excellent performance due to the large surface area of the micropores 51.

9 is a graph showing the electrical conductivity of the graphene 31 (Preparation Examples 1 to 4) coated with the ultra-thin carbon film 50 according to an embodiment of the present invention.

Referring to FIG. 9, it can be seen that the electrical conductivity characteristics are high in Preparation Example 2 (PUNG-2) to Preparation Example 4 (PUNG-4).

10 is a graph analyzing the catalytic activity characteristics of graphene 31 (Preparation Examples 1 to 4) coated with Pt/C and an ultra-thin carbon film 50 according to an embodiment of the present invention.

Referring to Figure 10, it is possible to compare the catalytic activity reactions of Pt/C and Preparation Examples 1 (PUNG-1) to 4 (PUNG-4) of the present invention.

In the case of Pt/C catalyst, there is a disadvantage that the price is expensive, but it is known that it is the best catalyst in terms of performance, so it can be seen that it has excellent catalytic activity performance. Able to know.

Here, referring to Table 1, it can be seen that when the ratio of the graphene 31 to the ultra-thin carbon film 50 wt% is 33 wt% to 43 wt%, similar performance to platinum is exhibited.

These are Preparation Example 2 (PUNG-2) and Preparation Example 3 (PUNG-3), and the numerical values can be clearly confirmed through Table 1 above. In particular, it shows superior performance in terms of current density than Pt, and the reason for this high current density is due to the generation of the ultra-thin carbon film 50 and its high oxygen affinity.

11 is a graph analyzing the number of electron transfers of graphene 31 (Preparation Examples 1 to 4) coated with Pt/C and the ultra-thin carbon film 50 according to an embodiment of the present invention.

Referring to FIG. 11, similar to platinum having excellent conductivity is when the ratio of graphene 31 to the carbon ultra-thin film 50 wt% is 33 wt% to 43 wt%, which is Preparation Example 2 (PUNG-3) and Preparation Example 3 As (PUNG-4), the numerical value can be clearly confirmed through Table 1 above.

12 is a graph comparing the ethanol resistance of Preparation Example 3 showing the best properties among graphene 31 coated with Pt/C and the ultra-thin carbon film 50 according to an embodiment of the present invention.

Referring to Figure 12, in the case of platinum, it can be seen that the activity decreases when ethanol is added to 100 s on the horizontal axis, but the graphene 31 coated with the ultrathin carbon film 50 according to the present invention is resistant to ethanol. It can be confirmed that the relative current maintains a high state even after 300 s of strength elapses.

13 is a graph analyzing the life characteristics of Preparation Example 3 in which Pt/C and the graphene 31 coated with the ultrathin carbon film 50 according to an embodiment of the present invention exhibit the most excellent characteristics.

Referring to FIG. 13, in the case of platinum, the relative current rapidly decreases as time passes, whereas the graphene 31 coated with the ultra-thin carbon film 50 according to the present invention maintains the relative current value not significantly different from the initial value for a long time. As you can see it falls. Looking at the graph, it was confirmed that the graphene 31 coated with the ultrathin carbon film 50 decreased by 8.9% while the relative current value of platinum decreased by 31.3% for 9 hours.

Therefore, it was confirmed through an experiment that safety, life, and current density are higher as well as excellent performance when compared to platinum catalyst (Pt/C).

The above description of the present invention is for illustrative purposes only, and those of ordinary skill in the art to which the present invention pertains will be able to understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not limiting. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as being distributed may also be implemented in a combined form.

The scope of the present invention is indicated by the claims to be described later, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention.

10: high molecular weight urea gel
20: organic matter solution
30: graphene oxide
31: graphene
40: polymer urea gel layer
41: mesopores
50: carbon ultra-thin film
51: micropore

Claims (13)

Preparing an organic material solution containing a nano-sized polymer urea gel;
Forming a polymer urea gel layer on the surface of the graphene oxide by mixing and reacting graphene oxide in the organic material solution;
Reducing the graphene oxide to form graphene coated with a polymer urea gel layer;
Forming mesopores in the polymer urea gel layer by first heat treating the graphene coated with the polymer urea gel layer; And
Forming an ultra-thin carbon film by carbonizing the polymer urea gel layer by secondary heat treatment of the graphene coated with the polymer urea gel layer;
Including,
In the process of performing the first heat treatment, the alkyl chain contained in the molecular network of the polymer urea gel disappears and mesopores are formed,
In the step of forming the ultra-thin carbon film, a method of producing graphene coated with an ultra-thin carbon film, wherein micropores are additionally formed in the ultra-thin carbon film as the polymer urea gel layer is carbonized.
The method of claim 1,
The nano-sized polymer urea gel is a method of producing graphene coated with an ultra-thin carbon film, characterized in that the surface is surrounded by amine or isocyanate functional groups.
The method of claim 1,
The first heat treatment temperature is a method of producing graphene coated with an ultra-thin carbon film, characterized in that 230 ℃ to 400 ℃.
The method of claim 1,
The second heat treatment temperature is 600 ℃ to 1000 ℃ method for producing a graphene coated with an ultra-thin carbon film, characterized in that.
delete The method of claim 1,
In the step of forming graphene coated with the polymer urea gel layer,
The method for producing graphene coated with an ultra-thin carbon film, wherein graphene is 5 wt% to 40 wt% based on the total weight of graphene coated with the polymer urea gel layer.
The method of claim 1,
In the step of forming the ultra-thin carbon film,
A method of producing graphene coated with an ultra-thin carbon film, wherein the ratio of graphene to the total weight of the graphene coated with the ultra-thin carbon film is 10 wt% to 50 wt%.
Graphene; And
Including a carbon ultra-thin film coated on the graphene surface,
It is characterized in that mesopores and micropores are formed in the carbon ultra-thin film,
Graphene coated with an ultra-thin carbon film, characterized in that the thickness of the ultra-thin carbon film is 10 nm or less.
The method of claim 8,
The graphene coated with the ultra-thin carbon film is graphene coated with an ultra-thin carbon film, characterized in that it contains 2wt% to 10wt% of nitrogen.
The method of claim 8,
Graphene coated with an ultra-thin carbon film, comprising pyridine or pyrrole in the graphene coated with the ultra-thin carbon film.
delete The method of claim 8,
The ultra-thin carbon film is graphene coated with an ultra-thin carbon film, characterized in that coated on one or both sides of the graphene.
The method of claim 8,
Graphene coated with an ultrathin carbon film, characterized in that the total surface area of the pores including the micropores and mesopores is 50 ㎡/g to 1000 ㎡/g.

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