Method for manufacturing porous graphene filter, porous graphene filter manufactured using same, and filter apparatus using porous graphene filter

Disclosed herein are porous graphene filters, each consisting of a carbon monoatomic layer having small holes formed therein during the graphene formation, a plurality of the porous graphene filters being used to selectively filter a specific material from a mixture of at least two different materials, a method for manufacturing the same, and a filtering apparatus using the same. The method comprises: separately forming a first graphene filter having a first hole of a first size and a second graphene filter having a second hole of a second size, during deposition of carbon atoms generated from a carbon source for formation of graphene, by substituting the carbon atoms, in part, with a substitution atom generated from a substitution source, the second size being larger than the first size; and arranging the first graphene filter and the second graphene filter in a filter body equipped with an inlet and an outlet.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates to a method for manufacturing a porous graphene filter, and a porous graphene filter manufactured by the method. More particularly, the present disclosure pertains to a method for manufacturing a porous graphene filter capable of selectively filtering a specific material from a mixture of at least two different materials, a porous graphene filter manufactured by the method, and a filtering apparatus using the porous graphene filter.

2. Description of the Related Art

Rapid development has been achieved in graphene technology over recent years.

Consisting of a planar monoatomic layer of carbon atoms, graphene has various advantages: it is far superior in conductivity to copper, it allows for faster electron mobility therein than in silicon, and it has even higher strength than steel. With these properties, graphene finds applications in a wide spectrum of fields including ultra-high speed semiconductors, flexible displays employing transparent electrodes, computer parts, high-efficiency solar cells, etc.

Technical development is ongoing in the area of graphene for use in semiconductors, displays, and solar cells, with particular direction toward avoiding the formation of defects, such as through-holes, therein.

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Patent Document

SUMMARY OF THE INVENTION

The present disclosure provides porous graphene filters, each consisting of a carbon monoatomic layer having small holes formed therein during the graphene formation, a plurality of the porous graphene filters being used to selectively filter a specific material from a mixture of at least two different materials, a method for manufacturing the same, and a filtering apparatus using the same.

An aspect of the present disclosure provides method for manufacturing a porous graphene filter, comprising: forming a first graphene filter having a first hole of a first size, during deposition of carbon atoms generated from a carbon source for formation of graphene, by substituting the carbon atoms, in part, with a substitution atom generated from a substitution source; forming a second graphene filter having a second hole of a second size, during deposition of carbon atoms generated from a carbon source for formation of graphene, by substituting the carbon atoms, in part, with a substitution atom generated from a substitution source, the second size being larger than the first size; arranging the first graphene filter and the second graphene filter in a filter body equipped with an inlet and an outlet.

In some embodiments, the substitution sources respectively used in the formation of the first graphene filter having the first hole and the second graphene filter having the second hole independently contain a nitrogen atom.

In some embodiments, the substitution source is provided in a smaller amount upon the formation of the first graphene filter, compared to the formation of the second graphene filter.

In some embodiments, the substitution source contains at least one selected from the group consisting of ammonia (NH3), hydrazine (N2H4), pyridine (C5H5N), pyrrole (C4H5N), acetonitrile (CH3CN), nitric acid (HNO3), silver nitrate (AgNO3), barium nitrate (Ba(NO3)2, N,N-dimethylformamide ((CH3)2NCHO), lithium nitride (Li3N), and cyanuric chloride (C3Cl3N3).

In some embodiments, the carbon source and the substitution source are simultaneously vaporized when the first graphene filter or the second graphene filter is formed.

Another aspect of the present disclosure provides a porous graphene filter, comprising: a first graphene filter in which a first hole with a first size is formed by substituting a part of carbon atoms having a crystal defect at a covalently bonded portion in the graphene with a substitution atom; a second graphene filter in which a second hole with a second size is formed by substituting a part of carbon atoms having a crystal defect at a covalently bonded portion in the graphene with a substitution atom; and a filter body in which the first graphene filter and the second graphene filter are immobilized against a path through which a mixture of a plurality of materials moves after the mixture is introduced into the filter body.

In some embodiments, the first graphene filter and the second graphene filter are independently in a film or cylindrical form.

A further aspect of the present invention provides a filtering apparatus, comprising: a mixture feeder for intermittently providing a predetermined amount of a mixture consisting of materials different in size from each other; a graphene filter comprising: a filter body equipped with an inlet through which the mixture is introduced into the filter body, and at least two outlets at a side of the filter body; and at least one graphene film having holes formed therein, positioned between the outlets within the filter body, for separating the individual materials of the mixture from each other; and a recovery unit, connected to the outlet, for recovering the separated individual materials.

In some embodiments, wherein the mixture feeder comprises: a mixture reservoir for supplying the mixture; a container for receiving a predetermined amount of the mixture; and a discharge unit for discharging the mixture from the container.

In some embodiments, the discharge unit comprises a blower for providing air or inert gas to the container.

In some embodiments, the filtering apparatus further comprises: electric valves associated with the mixture feeder, the graphene filter, and the recovery unit; and a valve controller for controlling the electric valves.

In some embodiments, the graphene filter comprises: a first graphene filter, arranged within the filter body, with first holes of a first size formed therein; and a second graphene filter, arranged facing the first graphene filter within the filter body, with second holes of a second size formed therein.

As described, graphene films, each consisting of a monoatomic layer structure, can be fabricated in such a way that very small holes are formed therein during graphene formation, and the resulting porous graphene films are used as graphene filters to selectively filter or separate specific materials from a mixture containing the materials.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference now should be made to the drawings, throughout which the same reference numerals are used to designate the same or similar components. Below, a description will be given of preferred embodiments of the present invention in conjunction with the accompanying drawings. Throughout the accompanying drawings, the same reference numerals are used to designate the same or similar components. In the following description of the present invention, when it is determined that the detailed description of the related art would obscure the gist of the present invention, the description thereof will be omitted.

The technical term “graphene”, as frequently used herein, refers to a monoatomic layer structure of carbon having a hexagonal ring as a fundamental repeat unit in which one atom forms each vertex.

In the present disclosure, however, a monoatomic layer structure in which five or seven carbon atoms covalently bonded together as a basic repeat unit is also defined as “graphene”.

The technical term “crystal defect” or “defect”, as frequently used in connection with graphene, is defined as the break of at least one of the covalent bonds formed between some carbon atoms of graphene with the aim of substituting a nitrogen atom for the carbon atom.

FIG. 1is a flow chart of illustrating a method for manufacturing a porous graphene filter in accordance with some embodiments of the present disclosure.FIGS. 2 and 3are plane views of the first graphene filter and the second graphene filter described inFIG. 1, respectively.

With reference toFIGS. 1 and 2, first, a first graphene filter1for use in the manufacture of the porous graphene filter is fabricated to have a first hole (H1) with a first size (S1) on average (step S10).

In step S10of fabricating a first graphene filter1in which a first hole (H1) with a first size (S1) is formed, a carbon source containing a carbon precursor decomposable into carbon and hydrogen atoms at a high temperature is vaporized to form a graphene film.

In some embodiments of the present disclosure, the vaporization of the carbon source in conjunction with a deposition furnace allows for the simpler production of a porous graphene filter, compared to conventional processes.

According to particular embodiments of the present disclosure, materials available as the carbon source for the first graphene filter1may be hydrocarbons, which can be thermally decomposed into carbon atoms and hydrogen atoms, as exemplified by methane (CH4), ethane (C2H6), ethylene (C2H4), acetylene (C2H2), propane (C3H8), propylene (C3H6), butane (C4H10), pentane (C5H12), pentene (C5H10), cyclopentadiene (C5H6), hexane (C6H14), cyclohexane (C6H2), benzene (C6H6), toluene (C7H8), and xylene (C8H10). Other examples include methanol (CH3OH), carbon monoxide (CO), ethanol (C2H5OH), and acetone (CH3COCH3), which can also produce carbon and hydrogen atoms by pyrolysis.

During the formation of graphene with carbon atoms generated by the vaporization of the carbon source, a substitution source (or doping source) is vaporized to generate a substitution atom that causes a crystal defect to a part of the carbon atoms in the graphene and substitutes for the carbon atoms having a crystal defect, in order to form the first hole (H1) having a first size (S1) on average in the graphene.

For the substitution source, a nitrogen precursor comprising a nitrogen compound may be available in some embodiments of the present disclosure.

Examples of the nitrogen compounds available as the substitution source for use in the formation of the first hole (H1) in the first graphene filter1include: ammonia (NH3), hydrazine (N2H4), pyridine (C5H5N), pyrrole (C4H5N), acetonitrile (CH3CN), nitric acid (HNO3), silver nitrate (AgNO3), barium nitrate (Ba(NO3)2), N,N-dimethylformamide ((CH3)2NCHO), lithium nitride (Li3N), and cyanuric chloride (C3Cl3N3).

In some embodiments of the present disclosure, the carbon source for providing carbon atoms for use in the formation of the first graphene filter1, and the substitution source for providing a substituent for use in the formation of a first hole (H1) having a first size (S1) on average during the formation of the first graphene may be vaporized in a simultaneous manner in respective vessels.

After simultaneous vaporization, evaporants from the carbon source and the substitution source are independently introduced into a deposition furnace in which a process condition suitable for the formation of the first graphene filter1is established, and are mixed therein.

The vaporized carbon source is thermally decomposed into carbon atoms and hydrogen atoms in the deposition furnace. The hydrogen atoms are released outside the deposition furnace while the carbon atoms are deposited on a substrate to form a monoatomic layer structure in the deposition furnace.

During the formation of carbon atoms into a film in the deposition furnace, the substitution source introduced into the deposition furnace is decomposed in the deposition furnace to generate nitrogen atoms that cause a crystal defect by acting on the covalently bonded portion of a part of carbon atoms and bond to the broken covalently bonded portion of the carbon atoms.

With the substitution of the nitrogen atoms for the carbon atoms of the crystal defect, a first graphene filter1in which a first hole (H1) having a first size (S1) on average is formed is fabricated.

In some embodiments of the present disclosure, when more carbon atoms are disconnected from the lattice and a greater number of nitrogen atoms participate in the formation of the crystal defect, the first hole (H1) of the first graphene filter1has an increased first size (S1).

In other words, the number of the first holes (H1) formed in the first graphene filter1and the mean value of the first sizes of the first holes (H1) are determined according to the ratio of the carbon source to the substitution source or the concentration of the substitution source.

An increase in the level of the substitution source relative to the carbon source induces the generation of crystal defects associated with more carbon atoms in the graphene, and nitrogen atoms are bonded in place of the carbon atoms, thereby increasing the number and the mean value of the first size of the first holes (H1).

On the other hand, a decrease in the level of the substitution source relative to the carbon source induces the generation of crystal defects associated with fewer carbon atoms in the graphene, and nitrogen atoms are bonded in place of the carbon atoms, thereby decreasing the number and the mean value of the first sizes of the first holes (H1).

Data about the mean value and deviation of the first sizes (S1) of the first holes (H1) formed in the graphene can be obtained with experiments in which the ratio of carbon source to substitution source is changed.

With reference toFIGS. 1 and 3, a second graphene filter2is fabricated to have a second hole (H2) with a second size (S2) on average (step S20) after or during the fabrication of the first graphene filter1.

In step S20of fabricating a second graphene filter2in which a second hole (H2) with a mean value of a second size (S2) is formed, a carbon source containing a carbon precursor is vaporized to form the graphene filter2.

According to particular embodiments of the present disclosure, materials available as the carbon source for the second graphene filter2may be hydrocarbons, which can be thermally decomposed into carbon atoms and hydrogen atoms, as exemplified by methane (CH4), ethane (C2H6), ethylene (C2H4), acetylene (C2H2), propane (C3H8), propylene (C3H6), butane (C4H10), pentane (C5H12), pentene (C5H10), cyclopentadiene (C5H6), hexane (C6H14), cyclohexane (C6H12), benzene (C6H6), toluene (C7H8), and xylene (C8H10). Other examples include methanol (CH3OH), carbon monoxide (CO), ethanol (C2H5OH), and acetone (CH3COCH3), which can also produce carbon and hydrogen atoms by pyrolysis.

In some embodiments of the present disclosure, the carbon source available for the fabrication of the second graphene filter2may be the same as or different from that used for the fabrication of the first graphene filter1.

During the fabrication of the second graphene filter2with carbon atoms generated by the vaporization of the carbon source, a substitution source (or doping source) is vaporized to generate a substitution atom for occupying the covalent bond broken by a crystal defect that is created to form the second hole (H2) having a second size (S2) on average in the graphene.

For the substitution source of the second graphene filter2, a nitrogen precursor comprising a nitrogen compound may be available in some embodiments of the present disclosure.

Examples of the nitrogen compounds available as the substitution source for use in the formation of the second hole (H2) in the second graphene filter2include: ammonia (NH3), hydrazine (N2H4), pyridine (C5H5N), pyrrole (C4H5N), acetonitrile (CH3CN), nitric acid (HNO3), silver nitrate (AgNO3), barium nitrate (Ba(NO3)2), N,N-dimethylformamide ((CH3)2NCHO), lithium nitride (Li3N), and cyanuric chloride (C3Cl3N3).

In some embodiments of the present disclosure, the substitution source available for the fabrication of the second graphene filter2may be the same as or different from that used for the fabrication of the first graphene filter1.

In some embodiments of the present disclosure, the carbon source for providing carbon atoms for use in the formation of the second graphene filter2, and the substitution source for providing a substituent for use in the formation of a second hole (H2) having a second size (S2) on average during the formation of the second graphene filter2may be vaporized in a simultaneous manner in respective vessels.

After simultaneous vaporization, the evaporants from the carbon source and the substitution source are independently introduced into a deposition furnace in which a process condition suitable for the formation of the second graphene filter2is established, and are mixed therein.

The vaporized carbon source is thermally decomposed into carbon atoms and hydrogen atoms in the deposition furnace. The hydrogen atoms are released outside the deposition furnace while the carbon atoms are deposited on a substrate to form a monoatomic layer structure in the deposition furnace.

During the formation of carbon atoms into a film in the deposition furnace, the substitution source introduced into the deposition furnace is decomposed in the deposition furnace to generate nitrogen atoms that cause a crystal defect by acting on the covalently bonded portion of a part of carbon atoms and bond to the broken covalently bonded portion of the carbon atoms.

With the substitution of the nitrogen atoms for the carbon atoms of the crystal defect, a second graphene filter2in which a second hole (H2) having a second size (S2) on average is formed is fabricated.

In particular embodiments of the present disclosure, the number of the second holes (H2) formed in the second graphene filter2and the mean value of the second sizes of the second holes (H2) are determined according to the ratio of the carbon source to the substitution source or the concentration of the substitution source.

An increase in the level of the substitution source relative to the carbon source induces the generation of crystal defects associated with more carbon atoms in the graphene, and nitrogen atoms are bonded in place of the carbon atoms, thereby increasing the number and the mean value of the second sizes S2of the second holes (H2).

On the other hand, a decrease in the level of the substitution source relative to the carbon source induces the generation of crystal defects associated with fewer carbon atoms in the graphene, and nitrogen atoms are bonded in place of the carbon atoms, thereby decreasing the number and the mean value of the second sizes S2of the second holes (H2).

Data about the mean value and deviation of the second sizes (S2) of the second holes (H2) formed in the graphene can be obtained with experiments in which the ratio of carbon source to substitution is changed.

On average, the second size (S2) of the second holes (H2) formed on the second graphene filter2in Step S20may be smaller than the first size (S1) of the first holes (H1) formed on the first graphene filter1in the step S10.

In this regard, the largest one of the second holes (H2) on the second graphene filter2may be smaller than the smallest one of the first holes (H1) on the first graphene filter1.

The second mean size (S2) of the second holes2formed in the second graphene filter2, although shown and described to be smaller than the mean size (S1) of the first holes1formed in the first graphene filter1, may be larger than the mean size (S1).

According to some embodiments of the present disclosure, the first graphene filter1in which first holes (H1) are formed to have a first size (S1) on average and the second graphene filter2in which second holes (H2) are formed to have a second size (S2) on average may be sequentially fabricated in one deposition furnace or separately in respective furnaces.

After being fabricated, both the first graphene filter1in which the first holes (H1) are formed to have the first size (S1) on average and the second graphene filter2in which the second holes (H2) are formed to have the second size (S2) on average are applied to a filter body to afford a porous graphene filter (step S30).

The filter body provides a path through which a mixture of at least two different materials passes, and the first graphene filter1and the second graphene filter2, respectively fabricated in steps S10and S20, are arranged in the path to filter off materials of interest through the first and the second holes (H1and H2) of the first and the second graphene filters1and2.

For instance, the porous graphene filter may be applied to the selective filtration of carbon dioxide from air, impurities from water, particular matters from vehicle emissions, and impurities or particular materials from blood.

FIG. 4is a block diagram illustrating an apparatus700for manufacturing a porous graphene filter.

Referring toFIG. 4, the apparatus700is configured to fabricate the first and the second graphene filter shown inFIG. 1

In some embodiments of the present disclosure, both the first graphene filter1and the second graphene filter2may be fabricated using one apparatus700for manufacturing a porous graphene filter. Alternatively, the first graphene filter1or the second graphene filter2may be fabricated using respective apparatuses700for manufacturing a porous graphene filter.

The apparatus700for manufacturing a porous graphene filter may comprise a material feeder, a simultaneous vaporizer, and a deposition furnace400. In addition, the apparatus700for manufacturing a porous graphene filter may further comprise a carrier gas supply500.

The material feeder may comprise a first material feeder210and a second material feeder220.

The simultaneous vaporizer may comprise a first vaporizer310and a second vaporizer320.

By the first material feeder210, a carbon source for use in the formation of graphene is fed into the first vaporizer310of the simultaneous vaporizer as described later.

The carbon source that is fed from the first material feeder210to the vaporizer310may be a carbon precursor including a hydrocarbon, which can be thermally decomposed into carbon atoms and hydrogen atoms.

In some embodiment of the present disclosure, the carbon precursor may be stored as a gas phase in the first material feeder210. In this case, the carbon precursor may be directly supplied into the deposition furnace400with the bypass of the first vaporizer310of the simultaneous vaporizer.

The second material feeder220acts to supply into the second vaporizer320of the simultaneous vaporizer a substitution source (or doping source) for use in the formation of through-holes in the graphene.

According to some embodiments of the present disclosure, the second material feeder220for supplying the substitution source into the second vaporizer320is associated with a material feeding controller225for precisely controlling the concentration of the substitution source and the feed rate of the substitution source.

As such, the material feeding controller225can alter the feed rate of the substitution source supplied to the second vaporizer320, allowing for the fabrication of the first graphene filter1, with first holes (H1) of a first size (S1) formed therein as shown inFIG. 2, and the second graphene filter2, with second holes (H2) of a second size (S2) formed therein as shown inFIG. 3.

Although the concentration and feed rate of the substitution source supplied from the second material feeder220to the second vaporizer320is described to be controlled by the material feeding controller225in the foregoing, each of the first and second material feeders210and220may be provided with an electric valve or mass flow controller (MFC) for controlling feeding rates of the carbon source and the substitution source in accordance with some embodiment of the present disclosure.

The substitution source supplied from the second material feeder220to the second vaporizer320may be a nitrogen precursor.

Examples of the nitrogen precursor available as the substitution source that is to be supplied to the second material feeder220as shown inFIG. 4include: ammonia (NH3), hydrazine (N2H4), pyridine (C5H5N), pyrrole (C4H5N), acetonitrile (CH3CN), nitric acid (HNO3), silver nitrate (AgNO3), barium nitrate (Ba(NO3)2), N,N-dimethylformamide ((CH3)2NCHO), lithium nitride (Li3N), and cyanuric chloride (C3Cl3N3).

In some embodiments of the present disclosure, when the nitrogen precursor is fed as a gas phase from the second material feeder220, it may be transmitted directly to the deposition furnace400, with the bypass of the second vaporizer320of the simultaneous vaporizer.

As described in the foregoing, the simultaneous vaporizer comprises the first vaporizer310and the second vaporizer320.

Communicating with the first material feeder210, the first vaporizer310may be fed with the carbon source, that is, a carbon precursor, from the first material feeder210.

The first vaporizer310comprises a container that is provided with an inlet through which a carbon precursor to be vaporized is introduced into the container and with an outlet through which a vaporized carbon precursor is released from the container. The inlet communicates with the first material feeder210while the outlet is connected with the deposition furnace400as will be described later.

In order to thermally vaporize the carbon precursor supplied to the first vaporizer310, a first heating furnace315may be provided outside the first vaporizer310while a heating wire316for generating heat may be arranged inside the first heating furnace315. Various heat generating devices other than the heating wire316may be provided for the first heating furnace315.

The second vaporizer320communicates with the second material feeder220and is supplied with a substitution source, e.g., a nitrogen precursor, from the second material feeder220.

The second vaporizer320comprises a container that is provided with an inlet through which a nitrogen precursor to be vaporized is introduced into the container and with an outlet through which a vaporized nitrogen precursor is released from the container. The inlet communicates with the second material feeder220while the outlet is connected with the deposition furnace400as will be described later.

For use in thermally vaporizing the nitrogen precursor supplied to the second vaporizer320, a second heating furnace325may be provided outside the second vaporizer320while a heating wire326for generating heat may be arranged inside the second heating furnace325. Various heat generating devices other than the heating wire326may be provided for the first heating furnace325.

Although the use of the first and second heating furnaces315and325comprising the heating wires316and326is described in the foregoing to vaporize the carbon and nitrogen precursors supplied to the respective first and second vaporizers310and320, the carbon and the nitrogen precursor may be chemically vaporized by providing a reactive gas.

Meanwhile, the carrier gas supply500for supplying carrier gas communicates with both the first vaporizer310and the second vaporizer320so that the carrier gas transmits the carbon precursor and the nitrogen precursor respectively vaporized in the first vaporizer310and the second vaporizer320to the deposition furnace400.

After being supplied from the carrier gas supply500to the first vaporizer310and the second vaporizer320, inert gas, such as nitrogen, argon, etc., transmits the carbon precursor and the nitrogen precursor vaporized respectively in the first vaporizer310and the second vaporizer320into the deposition furnace400.

In some embodiments of the present disclosure, the carrier gas supply500is connected with the first vaporizer310and the second vaporizer320via inert gas supplying pipes510and520, respectively. The inert gas-supplying pipes510and520may be conjugated with respective mass flow controllers (MFC).

According to some embodiments of the present disclosure, the flow rates of the inert gas from the carrier gas supply500to the first vaporizer310and to the second vaporizer320may be differently controlled so as to fabricate the first graphene filter1in which first holes (H1) of the first size (S1) are formed, and the second graphene filter2in which second holes (H2) of the second size (S2) are formed.

Turning toFIG. 4, the outlet of the first vaporizer310through which the carbon precursor vaporized in the first vaporizer is released is connected with a first pipe317while the outlet of the second vaporizer320through which the nitrogen precursor vaporized in the second precursor320is released is connected with a second pipe327.

Both the first pipe317and the second pipe318are convergent into a common pipe330that communicates with the deposition furnace400.

The vaporized carbon precursor and the nitrogen precursor are transmitted through the first pipe317and the second pipe327, respectively, and are mixed together in the common pipe330before entering the deposition furnace400. Thus, the vaporized carbon and nitrogen precursors proceed in the form of a uniform mixture towards the deposition furnace400.

In some embodiments of the present disclosure, the common pipe330may be equipped with a heating unit335so that the vaporized carbon and nitrogen precursors traveling through the common pipe respectively from the first pipe317and the second pipe327are prevented from being liquefied or deposited onto inside walls of the first and the second pipes317and327.

The heating unit335may comprise, for example, a heating wire that can generate heat with the consumption of electric energy. The heating unit335heats the common pipe330to minimize the temperature change of the vaporized carbon and nitrogen precursors.

In some embodiments of the present disclosure, the heating unit335, although described to be mounted onto the common pipe330where the vaporized carbon and nitrogen precursors are mixed in the foregoing, may be provided for each of the first pipe317and the second pipe327.

Turning again toFIG. 4, the deposition furnace400serves to establish a process condition and atmosphere under which the first and the second graphene filters1and2shown inFIGS. 2 and 3are fabricated with the carbon precursor supplied from the first vaporizer310through the first pipe317and the common pipe330, and with the nitrogen precursor supplied from the second vaporizer320through the second pipe327and the common pipe330.

The deposition furnace400establishing a process condition and atmosphere for forming the first and the second graphene filters1and2may be selected from the group consisting of chemical vapor deposition equipment, thermal chemical vapor deposition equipment, rapid thermal chemical vapor deposition equipment, inductive coupled plasma chemical vapor deposition equipment, and atomic layer deposition equipment.

Since a monoatomic layer is formed on a substrate disposed in the deposition furnace400, atomic layer deposition may be employed in some embodiments of the present disclosure.

The substrate, disposed within the deposition furnace400, onto which the first and the second graphene filters1and2are deposited, may be made of, for example, a metallic material that allows the first and the second graphene filters1and2to be easily separated from the substrate and which is unlikely to undergo deformation at a high temperature.

In some embodiments of the present disclosure, the metallic substrate disposed in the deposition furnace400may include a copper plate or a copper-plated plate.

Although the substrate, disposed in the deposition furnace400, on which the first and the second graphene filters1and2are deposited, is described to be a copper plate or copper-plated plate in the foregoing, various metallic substrates may employed as long as they allow the first and the second graphene filters1and2to be easily released from the substrates.

FIG. 5is a cross-sectional view of a porous graphene filter according to some embodiments of the present disclosure.FIG. 6is a conceptual view illustrating the filtration process of the porous graphene filter ofFIG. 5.

With reference toFIGS. 5 and 6, the porous graphene filter800comprises a first graphene filter1, a second graphene filter2, and a filter body750.

The first graphene filter1may be fabricated by the method illustrated inFIG. 1using the apparatus, shown inFIG. 4, for manufacturing the porous graphene filter. The first graphene filter1has the structure shown inFIG. 2.

The first graphene filter1is fabricated in such a way that, during the formation of graphene with carbon atoms generated by the vaporization of the carbon source, a substitution source is vaporized to generate substitution atoms, i.e., nitrogen atoms that cause a crystal defect to a part of the carbon atoms and substitute for the carbon atoms having crystal defect.

As shown inFIG. 2, the first graphene filter1has a first hole (H1) with a first size (S1).

The first graphene filter1may be formed into a film, as shown inFIG. 7. Given in the form of a film, the first graphene filter1may be engaged to a rectangular frame.

The first graphene filter1engaged to a rectangular frame shows very high tensile strength and compression strength.

In some embodiments of the present disclosure, the first graphene filter1may have a cylindrical form, as shown inFIG. 8. In this case, circular frames may be applied to opposite ends of the cylindrical first graphene filter1.

The cylindrical first graphene filter1engaged with the circular frames shows very high tensile strength and compression strength.

With reference toFIGS. 2 and 5, the second graphene filter2may be fabricated by the method illustrated inFIG. 1using the apparatus, shown inFIG. 4, for manufacturing the porous graphene filter. The second graphene filter2has the structure shown inFIG. 3.

The second graphene filter2is fabricated in such a way that, during the formation of graphene with carbon atoms generated by the vaporization of the carbon source, a substitution source is vaporized to generate substitution atoms, i.e., nitrogen atoms that cause a crystal defect to a part of the carbon atoms in the graphene and substitute for the carbon atoms having crystal defect.

As shown inFIG. 3, the second graphene filter2has a second hole (H2) with a second size (S2). The second size (S2) of the second holes of the second graphene filter2is larger than the first size (S1) of the first holes of the first graphene filter1.

According to some embodiments of the present disclosure, the second size of the second holes (H2) of the second graphene filter2may be changed by adjusting the concentration and feed rate of the substitution source relative to the carbon source.

The second graphene filter2may be formed into a film, as shown inFIG. 7. Given in the form of a film, the second graphene filter2may be engaged to a rectangular frame. The second graphene filter2engaged to a rectangular frame shows very high tensile strength and compression strength.

In some embodiments of the present disclosure, the second graphene filter2may have a cylindrical form, as shown inFIG. 8. In this case, circular frames may be applied to opposite ends of the cylindrical second graphene filter2.

The cylindrical second graphene filter2engaged with the circular frames shows very high tensile strength and compression strength.

In some embodiments of the present disclosure, both the first and the second graphene filters1and2may be formed, for example, into films, as shown inFIG. 7. Given in the form of films, the first and the second graphene filters1and2may be engaged to respective rectangular frames.

Although the first and the second graphene filters1and2are described to have rectangular film forms and to engage with respective rectangular frames in the foregoing, they may be formed into circular films and engaged to respective circular frames.

The first and the second graphene filters1and2engaged to respective frames may be arranged at a predetermined distance from each other within the filter body750as shown inFIG. 5.

The filter body750may have a columnar shape with both or one of the opposite ends open.

For example, the filter body750may be a column with open opposite ends responsible for an inlet752and an outlet754, respectively. The filter body750may be made of, for example, a metallic or synthetic resin material.

Through the inlet752of the filter body750, a mixture of at least two materials is introduced into the filter body while the resulting filtrate is discharged through the outlet754.

With reference toFIG. 6, when a mixture of material A larger than the first size (S1) of the first hole (H1) of the first graphene filter1, material B smaller than the first size (S1) of the first hole (H1) of the first graphene filter1and larger than the second size (S2) of the second hole (H2) of the second graphene filter2, material C, which is a target material, smaller than the second size (S2) of the second hole (H2) of the second graphene filter2, is introduced into the filter body750in which the first and the second graphene filters1and2are arranged at a predetermined distance from each other, and the target material C passes through both the first hole (H1) of the first graphene filter1and the second hole (H2) of the second graphene filter2whereas materials A and B cannot proceed through the first hole (H1) of the first graphene filter1or the second hole (H2) of the second graphene filter2.

FIG. 9is a block diagram illustrating a filtering apparatus according to some embodiments of the present disclosure.

The filtering apparatus according toFIG. 9allows for the separation of a mixture of at least two materials different in size into individual materials, and the recovery of the separated individual materials.

The filtering apparatus900comprises a mixture feeder, a graphene filter950, a recovery unit960, and a valve controller980.

In the filtering apparatus900, the mixture feeder feeds a mixture of at least two materials different in size into the graphene filter950as will be described later.

The mixture feeder comprises a mixture reservoir912, a container914, a discharge unit916, and electronic valves918and919.

After being provided with a mixture comprising material A with a first size on average, material B with a second size on average smaller than the first size, and material C with a third size on average smaller than the second size from an external source, the mixture reservoir912supplies the mixture to the container914.

The mixture reservoir912and the container914are connected with each other through a pipe913that is associated with an electric valve918for allowing or controlling the supply of the mixture into the container914. The electric valve918is opened or closed depending on a control signal from a valve controller980as will be described later.

The container914is connected with the pipe913and temporally stores a predetermined amount of the mixture.

The container914is also connected with a discharge pipe915for discharging a predetermined amount of the temporally stored mixture, and the discharge pipe915is associated with an electric valve919. This electric valve919serves to regulate the supply of the mixture temporally stored in the container914to the graphene filter950as will be described later.

Likewise, the electric valve919is opened or closed depending on a control signal from the valve controller980as will be described later.

The discharge unit916serves to supply the mixture temporally stored in the container to the graphene filter950.

For example, the discharge unit916may be connected to the pipe913and may include a blower for blowing air or inert gas to forcibly carry the mixture stored in the container914into the graphene filter950.

The graphene filter950comprises a filter body920and graphene films930and940arranged within the filter body. The filter body is equipped with an inlet921connected to the discharge pipe915of the container914, and outlets922,924, and926.

The filter body920may have a columnar shape with opposite ends closed. The inlet921is provided at an upper portion of the filter body920and is connected with the discharge pipe915of the container914. Through the inlet921, the mixture stored in the container914is introduced into the filter body920.

In the filter body920, the outlet may be established in such a number as to correspond to the number of the materials present in the mixture.

Because the mixture consists of three materials A, B, and C in some embodiments of the present disclosure, three outlets922,924, and926are arranged at predetermined distances from each other in the filter body920.

The graphene films930and940can be fabricated by the method illustrated inFIGS. 1 to 4, and accordingly a description of the configuration and fabrication method of the graphene films930and940will be omitted if it overlaps with that given in the foregoing.

The graphene film930is arranged in such a way as to block a passage through the filter body920.

For example, the graphene film930has first holes of a first size through which materials B and C can pass, but material A cannot.

The graphene film930is positioned between the outlets922and924.

Facing the graphene930within the filter body920, the graphene film940is also arranged in such a way as to block a passage through the filter body920.

For example, the graphene film940has second holes of a second size through which material C can pass, but material B cannot.

The graphene film940is position between the outlets924and926.

Communicating with the outlets922,924, and926, the recovery unit960separately recovers and stores materials A, B, and C from the mixture.

The recovery unit960comprises electric valves962,964, and966for use in selectively recovering and storing materials A, B, and C.

The valve controller980produces control signals for opening or closing the electric valves918,919,962,964, and966to selectively recover individual materials from a mixture thereof.

While the graphene filter depicted inFIG. 6is difficult to apply for the selective filtration or separation of any one of materials A, B, and C from a mixture thereof, the filtering apparatus illustrated inFIG. 9allows for the selective filtration or separation of materials A, B, and C that are different in size one another.

Below, a description will be given of the role of the filtering apparatus illustrated inFIG. 9in selectively separating or filtering individual materials from a mixture thereof.

First, a mixture of materials A, B, and C is supplied from the mixture reservoir912of the mixture feeder to the container914through the pipe913.

In this regard, the valve controller980applies a control signal to the electric valve918so as to direct the opening of the electric valve918for a predetermined period of time during which a predetermined amount of the mixture is fed into the container914through the pipe913.

When the container914is filled with a predetermined amount of the mixture, the valve controller980applies a control signal to the electric valve918so that the electric valve918is closed to block the supply of the mixture to the container914.

On the other hand, when the container914is filled with a predetermined amount of the mixture, the valve controller980directs the electric valve919connected to the discharge pipe915to open, thereby supplying air or inert gas from the discharge unit916to the container916, with the concomitant transmission of the mixture from the container914to the graphene filter850.

After entering the graphene filter950from the container914through the inlet921, the mixture reaches the graphene film930with first holes of the first size formed therein. Materials B and C of the mixture pass through the first holes whereas material A cannot pass through the holes, thereby remaining on the graphene film930.

Materials B and C, after passing the graphene film930, reach the graphene film940, with second holes of the second size formed therein, at which material C passes through the second holes while material B remaining on the graphene film940.

Accordingly, while a predetermined amount of the mixture is supplied from the container914to the graphene filter950, materials A, B, and C are separated individually by the graphene films930and940of the graphene filter950.

As such, materials A, B, and C that are divided from one another by the graphene films930and940are individually recovered through the respective outlets922,924, and926into the recovery unit960. The valve controller980produces control signals directing the opening and closing of the electric valves962,964, and966respectively connected to the outlets922,924, and926.

In accordance with some embodiments of the present disclosure, the mixture may comprise gaseous, liquid, or solid materials different in size.

In accordance with some embodiments of the present disclosure, the filtering apparatus may find applications in a variety of fields including the medical field, the filtration field for specific gas separation, etc.

As elucidated hitherto, graphene films consisting of a monoatomic layer structure can be fabricated in such a way that holes of predetermined sizes are formed therein during graphene formation, and the resulting porous graphene films are used as graphene filters to selectively filter or separate specific materials from a mixture containing the materials.

Embodiments illustrated in the drawings are set forth to illustrate, but are not to be construed as limiting the present invention. It should be apparent to those skilled in the art that although many specified elements such as concrete components are elucidated in the following description, they are intended to aid the general understanding of the invention and the present invention can be implemented without the specified elements.