KR101533034B1 - Reduced graphene oxide, preparing method thereof, and ink including the same - Google Patents

Abstract

The present invention relates to reduction graphene oxide, a manufacturing method of the reduction graphene oxide, and an ink including the reduction graphene oxide. The manufacturing method of the reduction graphene oxide comprises the steps of: irradiating light into a mixture of a metal and a photo-sensitizer and ionizing the same to form a reducing agent; and adding graphene oxide into the mixture in which the reducing agent is formed and reducing the same to form the reduction graphene oxide.

Description

TECHNICAL FIELD [0001] The present invention relates to reduced graphene oxide, a process for producing the same, and an ink containing the same. BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to reduced graphene oxide, a process for producing the reduced graphene oxide, and an ink comprising the reduced graphene oxide.

Graphene and other two-dimensional nanomaterials have received great interest for a wide range of applications due to their unique two-dimensional structure and attractive advantages, including high conductivity, optical transparency, gas barrier properties, flexibility and environmental stability . For the production of high quality crystalline graphene sheets, graphene is typically produced by mechanical stripping and chemical vapor deposition (CVD). However, the application of such conventional methods is limited due to the difficulties of reproduction and mass production of graphene. In order to overcome the above-mentioned limiting factors, the chemical exfoliation of graphene oxide (GO) by chemical reduction after ultrasonic dispersion or rapid thermal expansion has been accompanied by a large amount of graphene flake (reduced graphene oxide oxide, rGO)] has been employed as a chemical vapor deposition process. The graphene flakes are widely used in a variety of applications including electronics, sensors, biocompatible materials, and electrochemical energy storage and conversion devices. To date, numerous reducing compounds such as sodium hydride, hydrogen sulfide, hydrazine, NaBH ₄ , dimethyl hydrazine, hydroquinone, NaBH ₄ and sequential use of sulfuric acid, HI-AcOH, vitamin C and aluminum powder, Was used to reduce GO to produce rGO.

Direct reduction of the GO film by conventional methods has been reported. However, these methods often require high temperature treatments that involve highly toxic chemicals, require long reduction times, or are incompatible with flexible plastic substrates and produce rGO with relatively high oxygen content. Recently, sodium combined with liquid NH ₃ has been reported for effective conversion of GO thin films to rGO thin films, which requires very low temperatures (-78 ° C). However, this method makes it impossible to handle the film at room temperature and is not environmentally friendly due to the use of liquid NH ₃ . it is required to rapidly reduce the GO to rGO at room temperature and simultaneously produce high purity rGO so as to enable direct patterning of the GO which can generate the rGO channel. In addition, the development of new methods of reduction of environmentally friendly, mild, and cost effective use of weakly toxic or non-toxic chemicals remains a challenge. To date, there have been few reports relating to easy and direct patterning of GO to N-doped or highly undoped rGO at room temperature with very short reaction times.

Korean Patent Laid-Open No. 10-2012-0064364 discloses a polyamic acid composition comprising graphene oxide in which a part of the oxide groups are reduced and a method for producing the same.

Accordingly, the present invention provides a reduced graphene oxide, a method for producing the reduced graphene oxide, and an ink containing the reduced graphene oxide.

However, the problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

According to a first aspect of the present invention, there is provided a method for manufacturing a semiconductor device, comprising: irradiating a mixture containing a metal and a photosensitive agent with light to form a reducing agent; And reducing grains by adding graphene oxide to the mixture in which the reducing agent is formed to form reduced graphene oxide.

The second aspect of the present invention provides a reduced graphene oxide produced according to the manufacturing method of the first aspect.

The third aspect of the present invention provides an ink comprising reduced graphene oxide according to the second aspect.

According to any one of the above-mentioned means for solving the problem, the present invention is directed to a process for the rapid reduction of a GO to a high quality rGO that is N- doped or not doped N- by simple light exposure at room temperature on a solid substrate, , Which allows direct patterning of high quality rGO electrodes that are N-doped or non-doped at room temperature. The present invention contemplates a novel reducing agent of the sodium-benzophenone system (Na-BH) in the presence of sodium-benzophenone (Na-B) or hydrazine capable of producing high quality rGO at N- did. It is presumed that newly generated radical anions utilizing electrons generated from sodium-benzophenone in the presence of light can reduce the GO to the rGO sheet on the solid substrate as well as the solution phase. In addition, the Na-B-H system can tolerate a high level of reduction with the doping of N (nitrogen) atoms by the introduction of hydrazine, which helps to reduce the surface resistance. Compared with other reported methods involving hydrazine reduction and sodium-ammonia or direct thermal annealing, it is possible to produce graphene with very few residual functionalities and low surface resistivity using N-doping in a short time at room temperature In addition, it can provide the effect of providing a very environmentally friendly protocol.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a graph illustrating the effect of reduced graphene oxide (rGO _{Na -B1} ) and sodium-benzophenone-hydrazine by sodium-benzophenone (Na-B) system upon in situ direct patterning of rGO at room temperature, (RGO & lt _{; / RTI &gt}; _Na-B-H2 ) N-doped by the sodium (Na-BH) system.
2 is a schematic diagram illustrating a reduction mechanism and process capable of producing an rGO _{Na- B1} sheet using a solvated radical anion having an electron from sodium in one embodiment of the present invention.
Figure 3 is, rGO using sodium hydrazide conjugate, ₂ H NaN ₃ according to one embodiment of the present _Na-H3 and rGO _{Na - H4} Lt; RTI ID = 0.0 > schematically < / RTI >
4A is a graph showing XPS spectra of graphene oxide, reduced graphene oxide (rGO _{Na- B1} ), and N-doped reduced graphene oxide (rGO _Na-B-H2 ) in one embodiment of the present invention .
4B is a graph showing the C1s XPS spectrum of graphene oxide, reduced graphene oxide (rGO _{Na- B1} ), and N-doped reduced graphene oxide (rGO _Na-B-H2 ) in one embodiment of the present invention to be.
Figure 4c, in one embodiment of the present GO (red), an N- doped reduction of graphene oxide _(Na rGO _{-B- H2)} (blue), reduction of graphene oxide _(Na rGO _-B1) (green), And powder XRD pattern of graphite (black).
FIGURE 4d, in one embodiment of the present GO (green), and reduction of graphene oxide _(Na rGO _-B1) (blue), an N- doped reduction of graphene oxide _(Na rGO _{-B- H2)} (red), And graphite (black).
5 is a graph showing the XPS spectrum of graphite in one embodiment of the present invention.
Figure 6 is a graphical representation of rGO & lt _{; RTI ID = 0.0 & gt ; Na- B- H2} Lt; RTI ID = 0.0 > N1s < / RTI >
Figure 7 is a graphical representation of rGO & lt _; RTI ID = 0.0 & gt _{; Na - H3} And rGO _{Na - H4} ≪ SEP > XRD < SEP >
Figure 8 is a graph showing the XRD spectra of GO and GO solutions treated under UV lamps for about 24 hours in one embodiment of the invention.
Figure 9 is a graphical representation of rGO & lt _; RTI ID = 0.0 & gt _{; Na - H3} And rGO _{Na - H4} ≪ SEP > FTIR < SEP >
Figure 10a, according to one embodiment of the present GO (black), reduction of graphene oxide _(Na rGO _-B1) (red), and the N- doped reduction of graphene oxide _(Na rGO _{-B- H2)} (blue) ≪ / RTI >
Figure 10b, according to one embodiment of the present GO (green), and reduction of graphene oxide _(Na rGO _-B1) (red), an N- doped reduction of graphene oxide _(Na rGO _{-B- H2)} (Black), And a reduced graphene oxide comparative sample (rGO _H ) (blue) produced by hydrazine.
FIG. 10C is an image showing the water contact angle of (i) GO, (ii) rGO _H , (iii) rGO _{Na -B1} , and (iv) rGO _{Na- B-H2} in one embodiment of the present invention.
10D is a SEM image of the surface of (GO), (ii) rGO _H , (iii) rGO _{Na -B1} , and (iv) rGO _{Na- B-H2 in one embodiment} of the present application.
FIG. 11 is a graph of rGO _H , rGO &_lt; _{RTI ID} = 0.0 &_gt; _{Na - H3} , rGO _{Na - H4} Raman spectrum of the sheet.
Figure 12 is a graphical representation of an embodiment of the present invention wherein GO, rGO & lt _; RTI ID = 0.0 & gt _{; Na - H3} , rGO _{Na - H4} Lt; RTI ID = 0.0 > TGA < / RTI >
Figures 13 (a) and 13 (b) are AFM images of the rGO _{Na- B1} sheet prepared using the Na-B system and the Na-BH system in one embodiment of the invention.
Figures 14 (a) - (c) illustrate rGO _{Na - H3} , rGO _{Na - H4} Sheet, and graphite.
Figure 15 (a) is an image of a GO film on PET in the presence of background light in one embodiment of the invention.
FIG. 15 (b) shows the rGO _{Na -B1} and rGO _{Na- B- H2} ≪ / RTI > is an image of a patterned SKKU on a GO film.
FIG. 15 (c) shows cross-sectional rGO _{Na -B1} and rGO _{Na- B-H2} patterned SKKUs on a PET film of about 199 Ω per square and about 137.1 Ω per square surface resistance, respectively, (D) of FIG. 15 shows cross-linked rGO _{Na -B1} and rGO _{Na- B- H2} patterns on a PET film on a PET film showing a surface resistance of about 198.1 Ω per square and about 127.4 Ω per square, respectively, It is an image of SKKU.
15 (e) is an image of a GO film on PET in one embodiment.
15 (f) is an image of a line pattern on the GO film by the surface resistance of about 135.9 Ω per square rGO _{Na -B1} , rGO _{Na -B1} and rGO _{Na- B- H2} in one embodiment, and FIG. g) is about 194.9 Ω per square rGO _{Na- B- H2} Surface resistance, rGO & lt _{; / RTI} & gt _{; Na- B1} and rGO _{Na- B- H2} on PET.
16 is an image of GO and rGO films on PET in one embodiment of the invention.
Figure 17 shows the cross-linked rGO & lt _{; RTI ID = 0.0} & gt _{; Na- B1} & lt _{; / RTI} & gt _; and rGO _{Na- B- H2} on the GO film producing SKKU structures on PET in one embodiment of the invention It is an image that represents the production of a pattern.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. It should be understood, however, that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, the same reference numbers are used throughout the specification to refer to the same or like parts.

Throughout this specification, when a part is referred to as being "connected" to another part, it is not limited to a case where it is "directly connected" but also includes the case where it is "electrically connected" do.

Throughout this specification, when a member is "on " another member, it includes not only when the member is in contact with the other member, but also when there is another member between the two members.

Throughout this specification, when an element is referred to as "including " an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise.

The terms "about "," substantially ", etc. used to the extent that they are used throughout the specification are intended to be taken to mean the approximation of the manufacturing and material tolerances inherent in the stated sense, Accurate or absolute numbers are used to help prevent unauthorized exploitation by unauthorized intruders of the referenced disclosure.

The word " step (or step) "or" step "used to the extent that it is used throughout the specification does not mean" step for.

Throughout this specification, the term "combination (s) thereof " included in the expression of the machine form means a mixture or combination of one or more elements selected from the group consisting of the constituents described in the expression of the form of a marker, Quot; means at least one selected from the group consisting of the above-mentioned elements.

Throughout this specification, the description of "A and / or B" means "A or B, or A and B".

Hereinafter, embodiments of the present invention are described in detail, but the present invention is not limited thereto.

According to a first aspect of the present invention, there is provided a method for manufacturing a semiconductor device, comprising: irradiating a mixture containing a metal and a photosensitive agent with light to form a reducing agent; And reducing grains by adding graphene oxide to the mixture in which the reducing agent is formed to form reduced graphene oxide.

In one embodiment of the invention, it may additionally include, but is not limited to, adding hydrazine as a reducing agent to the mixture prior to irradiating the light. For example, the N-doping may be performed simultaneously with the reduction of graphene oxide by hydrazine, but may not be limited thereto.

In one embodiment of the invention, the metal may include but is not limited to those selected from the group consisting of Na, Li, K, and combinations thereof.

In one embodiment of the present invention, the photosensitizer may include, but is not limited to, benzophenone.

In one embodiment of the invention, the reducing agent formed by the ionization may be, but not limited to, produce a solvated radical anion or metal hydrazide complex.

In one embodiment herein, the ionization may be performed at a temperature of from about 0 캜 to about 100 캜, but may not be limited thereto. For example, the ionization may be performed at a temperature of from about 0 캜 to about 100 캜, from about 10 캜 to about 100 캜, from about 20 캜 to about 100 캜, from about 30 캜 to about 100 캜, From about 0 DEG C to about 90 DEG C, from about 0 DEG C to about 100 DEG C, from about 60 DEG C to about 100 DEG C, from about 70 DEG C to about 100 DEG C, from about 80 DEG C to about 100 DEG C, from about 90 DEG C to about 100 DEG C, From about 0 째 C to about 30 째 C, from about 0 째 C to about 20 째 C, from about 0 째 C to about 70 째 C, from about 0 째 C to about 60 째 C, from about 0 째 C to about 50 째 C, , Or from about 0 < 0 > C to about 10 < 0 > C.

A second aspect of the present invention provides a reduced graphene oxide produced according to the first aspect of the present invention.

The above technical information relating to the first aspect of the present application applies to the second aspect of the present invention.

In one embodiment of the present invention, the C / O ratio of the reduced graphene oxide may be about 5 or more, but is not limited thereto.

In one embodiment of the present invention, the surface resistivity of the reduced graphene oxide may be about 300 Ω / m 2 or less, but may not be limited thereto.

A third aspect of the invention provides an ink comprising a reduced graphene oxide according to the second aspect of the invention.

The above technical information concerning the second aspect of the present application applies to the third aspect of the present invention.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following Examples are given for the purpose of helping understanding of the present invention, but the present invention is not limited to the following Examples.

[ Example ]

<Characteristic Analysis>

All X-ray photoelectron spectroscopy (XPS) measurements were obtained by SIGMA PROBE (ThermoVG, UK) with a monochromatic Al-K? X-ray source at 100 W. Powder XRD patterns were obtained using D8-Adcance instrument (Germany) and Cu-Kα radiation. Raman spectroscopy measurements were obtained using a micro-Raman system (Renishaw, RM1000-In Via) using excitation energy of 2.41 eV (514 nm). The thermal properties of rGO were characterized by TGA (Polymer Laboratories, TGA 1000 plus). FT-IR spectra were collected using a Thermo Nicolet AVATAR 320 instrument. Microstructures were observed by field emission scanning electron microscopy (FE-SEM; JSM-6701F / INCA Energy, JEOL). Atomic force microscopy (AFM) analysis was performed at room temperature using a SPA400 instrument equipped with an SPI-3800 controller (Seiko Instrument Industry Co.). The contact angle was measured using the SEO Phoenix 300 microscope at five different points.

< Experimental Example  One: Grapina Of oxide (GO)  Manufacturing>

GO was prepared from natural graphite powder (Bay Carbon, SP-1 graphite) by the method of Hummers and Offenman modified with sulfuric acid, potassium permanganate and sodium nitrate.

< Experimental Example  2: sodium and Benzophenone  Reduction by Grapina Oxide (rGO _Na-B1 )of  Manufacturing>

A 50 mL two-round bottom flask was removed from the hot oven and flushed with nitrogen. A sample of freshly distilled and deoxygenated tetrahydrofuran (THF) and a sample of benzophenone (100 mg) with a stir bar was placed in the flask. A small piece of sodium metal (350 mg) was cut into smaller pieces and injected directly into the flask against an injection stream of nitrogen. The second neck of the flask was sealed with a water condenser. The mixture was stirred under nitrogen for 30 minutes until a blue color was produced by heating at 40 占 폚 in an oil bath in the presence of a UV lamp (254 nm) or normal sodium light. 20 mg of a dispersed dried GO in 5 mL of dry THF was then added to the solution, and stirring was continued for an additional 40 minutes under the same conditions. Finally, a black rGO _{Na- B1} solution was obtained. The rGO _{Na- B1} was collected by simple filtration and washing with ethanol and water.

< Experimental Example  3: sodium, Benzophenone  And Hydrazine  N- Doped  restoration Grapina  Oxide ( rGO _Na-B-H2 )of  Manufacturing>

First, as described above, a blue solution was prepared in the presence of a UV lamp. 20 mg of dry GO was dispersed in 5 mL of hydrazine in THF solution. The GO solution was then added to the Na-B solution, and stirring was continued for an additional 30 minutes under the same conditions for 15 minutes after mixing. Finally, black rGO & lt _{; RTI ID = 0.0 & gt ; Na- B- H2 &} Solution. The rGO _{Na- B- H2} was collected by simple filtration and washing with ethanol and water.

< Experimental Example  4: sodium Hydrajite  Reduction by complex Grapina Oxide (rGO _Na-H )of  Manufacturing>

A small piece of sodium metal (100 mg) was first cut into smaller pieces and placed directly into a two-round flask against a nitrogen injection stream. Hydrazine was then added to the flask in 5 mL of THF solution and heated at 50 DEG C for 1 hour in an oil bath. A white complex was formed, followed by the addition of 10 mg of dispersed dried GO in THF solution (5 mL) and stirring continued for an additional hour under the same conditions. Finally, rGO _{Na - H3} was produced. The dried GO was dispersed in the hydrazine-THF solution, followed by addition of sodium and heating at 50 &lt; 0 &gt; C for 1 hour with continued stirring. Finally rGO _{Na - H4} was obtained.

< Experimental Example  5: GO  And RGO  Production of Film>

GO films were prepared and carefully transferred onto PET films according to previously reported procedures [H. Feng, R. Cheng, X. Zhao, X. Duan, J. Li, Nat. Commun. 2013, 4, 1539.]. The GO / PET film was immersed in Na-B or Na-BH solution for several minutes. The rGO / PET film was then washed with saturated sodium bicarbonate, water, and ethanol and dried at room temperature. The color of the rGO / PET film changed from light brown to black.

< Experimental Example  6: Patterned rGO _{Na -B1}  And rGO _{Na -B- H2} of  Production>

First, a GO film was prepared on PET. At the same time, Na-B and Na-BH solutions were also prepared. Generally, brushes were used to make cross patterns such as SKKU and lines on the GO film using Na-B and Na-BH solutions in the presence of UV lamps. Finally, the remaining GO was removed by washing very carefully using water. As a result, the cross-patterned rGO _{Na- B1} and rGO _{Na- B- H2} The structure was created.

In this example, the novel concept of the present invention to find a novel reducing agent proceeded as shown in Fig. Metallic sodium could react with benzophenone to form a dark colored solution with strong affinity for reacting with oxygen functional groups due to the formation of the solvated radical anion 'diphenylketyl' with electrons. The reaction of sodium metal with benzophenone resulted in the ionization of the metal to form solvated radical anions with sodium cations and electrons (FIGS. 1 and 2). The dark color of the sodium metal in the solution was due to the presence of solvated radical anions with electrons. Generally, these electrons and solvated radical anions were generated by heating at ~ 40 ° C. Since benzophenone is well known as a photosensitizer in photochemical applications, instead of applying a heat treatment at high temperature for a long time, the present invention only activated the solution system at room temperature by introducing UV light. The role of benzophenone is to transfer the necessary energy from the UV light to the solution system to produce solvated radical anions and electrons with the reaction of the sodium metal. We also used conventional heating (~ 40 ° C) to produce solvated radical anions with electrons and typical sodium light, which caused a temperature higher than room temperature. To prepare our more competitive solution system as a reducing agent with N (nitrogen) doping properties, we added anhydrous hydrazine in sodium and benzophenone solutions. According to the literature, anhydrous hydrazine reacted with the sodium metal and a sodium hydrazide complex, NaN ₂ H ₃ (Figure 3), was obtained. According to this example, the solution obtained simultaneously produced a solvated radical anion containing electrons and a sodium hydrazide complex. It is also assumed that the two solution systems according to this embodiment effectively remove oxygen functionality and restore the planar geometry of the GO sheet due to the strong affinity of the GO sheet for oxygen.

We prepared two solution systems, Na-B and Na-BH. The dried GO powder was first dispersed in anhydrous hydrazine-THF solution and stirred for 20 minutes to make a stable dispersion of GO. Several pieces of sodium metal were added to the benzophenone in the THF solution followed by the addition of GO in the hydrazine solution at room temperature in the presence of UV light. A solution of black N-doped rGO (rGO _{Na- B- H 2} ) was obtained after the reduction of the GO in the resulting solution with the solvated radical anion having electrons and the complex. However, in the Na-B system, the dried GO was dispersed in THF, and then Na-B solution was added to produce rGO (rGO _Na-B1 ). Possible reduction mechanisms according to this embodiment are shown in FIG. 2 and FIG. As a control experiment, we prepared only the NaN ₂ H ₃ complex by reaction of sodium metal with anhydrous hydrazine-THF solution at ~ 50 ° C, followed by the addition of GO dispersed in THF. This is rGO _{Na - H3} Resulting in the creation of a sheet. We also dispersed the dried GO powder in anhydrous hydrazine-THF solution and then stirred for 20 minutes to make a stable dispersion of GO to produce a rGO _Na-H4 sheet. Experimental analysis suggests that rGO _{Na - H4} is more reduced than rGO _{Na - H3} due to the reduced form of the complex in this complex. This is also the first example of using a NaN ₂ H ₃ complex as a reducing agent to make an rGO sheet. In the case of UV light and general light at room temperature, benzophenone acts as a photosensitizer for complexing with sodium, which is very effective in reacting with oxygen functional groups of GO.

In one embodiment of the present application, X- ray photoelectron spectroscopy (XPS) was used to measure the chemical structure and composition of the rGO _{Na -B1} and rGO _Na-B-H2 powder samples prepared. Based on the XPS analysis, the prepared GO had a very high oxygen atomic percentage (C / O ratio of 2.01, Fig. 4A). Figure 4b GO, rGO _{Na -B1,} and _-B- rGO _{Na H2} The C1s spectrum of the powder sample is shown. As shown in Figure 4b, GO generally exhibited two separate peaks because the oxidation process produced a high proportion of oxygen functionality. After reduction using the Na-B and Na-BH systems, the intensities of all the associated oxygen peaks were compared with the rGO _{Na -B1} and rGO _{Na- B- H2} Sample showed a predominance of C = C bonds as evidenced by a single peak near 284.5 eV with a small tail in the higher binding energy region, indicating that rGO _Na-B1 and rGO Excellent restoration of C = C bond in _{Na- B- H2} was confirmed (Fig. 4b). The rGOs prepared by the present invention were concluded to contain less oxygen, which was very similar to graphite and was of high quality (Fig. 5). For comparison, the C / O ratios of rGO _{Na -B1} and rGO _{Na- B- H2} produced by reduction of the Na-B and Na-BH systems were 13.9 and 16.2, respectively (FIG. Herein it was observed for ~ 3.8% of nitrogen in the rGO (rGO _{Na -B- H2)} produced by the presence of a nitrogen source (hydrazine) of Na-BH system. The corresponding N1s XPS spectrum of rGO &lt; RTI ID = 0.0 & _{gt ; Na- B- H2} &lt; / RTI &gt; We also used XPS to determine the rGO _{Na - H3} and rGO _{Na - H4} atomic composition. Significantly, the rGO _{Na - H3} and rGO _{Na - H4} The samples showed relatively low C / O ratios of 10.9 and 12.6 and lower oxygen percentages (see Table 1, below). The rGO _{Na - H4} The sample was reduced more than rGO _{Na - H3} . The products produced were fairly distinct from rGO obtained by reduction products using only hydrazine.

[Table 1]

X-ray diffraction (XRD) is an effective and convenient method for demonstrating the degree of reduction of rGO. Powder XRD analysis was used to characterize the bulk structure of the prepared rGO _{Na -B1} and rGO _{Na- B- H2} (Figure 4c). The 2 &amp;thetas; peak of the graphite powder appeared at 26.71 DEG, corresponding to an interlayer distance of 3.34 A DEG (FIG. 4C). On the other hand, the prepared GO exhibited a 2? Peak at 10.27 °, indicating that the graphite was completely oxidized to GO with an inter-layer distance of 8.60 A °, which explained that interlayer space increased during the oxidation process 4c). The XRD pattern of the prepared rGO _{Na- B1} showed typical sharp 2 &amp;thetas; peaks at 23.7 DEG and an interlayer distance of ~ 3.75 A DEG (Fig. 4C). _{GO (10.27 °) rGO Na-} B1 powder (23.7 °) is displaced rGO _{Na -B1} the reduction process surface acts very well aligned in a two-dimensional surface by the removal of off-the-shelf oxygen during the peak of 2θ in the XRD pattern from the XRD pattern . rGO _{Na -B- H2} also showed the typical sharp peak 2θ at 24.6 °, ~ corresponds to an interlayer distance of 3.61 A °, has been described a higher degree of reduction than rGO _{Na -B1} powder (Fig. 4c). The interlayer distance of rGOs was 3.75 A ° and 3.61 A °, which was very close to the interlayer distance of graphite powder (3.34 A °). The XRD patterns of the rGO _{Na - H3} and rGO _{Na - H4} prepared were also provided in FIG. In this example, the GO solution was treated using a UV lamp for 24 hours as a control experiment, but no significant change was observed in the XRD data before and after treatment (FIG. 8).

In this example, we used Fourier Transform Infrared Spectroscopy (FTIR) to study the change in functional groups in the GO after the reduction process. Importantly, the FTIR spectrum clearly showed gradual removal of oxygen by the new system (Fig. 4d). Because the GO film was reduced by the system, the peaks of all oxygen functional groups were significantly or completely reduced. In fact, oxygen-containing groups can readily react with solvated radical anions with electrons prepared to decompose the carbon-oxygen bonds in the plane of the GO (FIG. 2). The FTIR results of the prepared rGOs are very similar to those of normal graphite. This confirmed that the material contained less oxygen and was of high quality (Figure 4d). The FTIR spectra of rGO _Na-H3 and rGO _{Na - H4} are provided in FIG. As previously reported, solvated electrons and π-conjugation partially dispersed within the GO plane stabilize carbon radicals in graphene to facilitate the formation of π-bonds and the restoration of π-conjugation, thereby obtaining an rGO sheet.

Raman spectra are the most direct and non-destructive technique for characterizing the structure and quality of carbon materials and, in particular, for determining graphene defects, alignment and unaligned structures. Figure 10a shows the micro-Raman spectrum of the graphite layer in the powder sample. The GO peak (1,609 cm ^-1 ) in the G-band was highly displaced compared to the peak of graphite (1,580 cm ^-1 ), indicating that the isolated double bond, which resonates at a higher frequency than that of the graphite G- It was due to existence. rGO _Na G- band of _-B1 and rGO _{Na -B- H2} was generated in each of 1,581 cm ^-1 and 1,583 cm ^-1, which was equivalent to a hexagonal network of carbon atoms having a fault recovery (Fig. 10a). I _D / I _G ratio of _Na rGO _{-B- H2} is in particular increased as compared with the GO rGO _{Na -B1,} which showed that they have changed the structure of the GO having a structural defect in the number of the reduction process amount. The higher proportion of Raman intensity (I _D / I _G ) of rGO _{Na -B1} and rGO _{Na- B- H2} than GO shows an increase in the number of smaller sp ² domains. The prepared rGO _{Na - H3} , rGO _{Na - H4} , and rGO _H (rGO) control samples produced by hydrazine also showed similar patterns in their Raman spectra (FIG. 11).

Thermogravimetric analysis (TGA) was used to determine the reduction level of the GO powder by measuring the weight loss of the sample. Figure 10b GO, rGO _{-B1 Na} and _Na rGO _{-B- H2} and _H rGO TGA Thermo grams (thermogram) showing the weight loss of the control sample as a function of the temperature obtained at a heat rate of 1 ℃ min ^-1 under a nitrogen atmosphere Respectively. GO samples exhibited significant weight loss at over 100 &lt; 0 &gt; C of onset temperature, which resulted from the elimination of interlamellar water, followed by the GO platelet itself (CO And by the release of CO ₂ ). rGO _{Na- B1} and rGO _{Na- B- H2} Each have a weight loss of ~ 10 wt% and ~ 7 wt% and the rGO _{Na -B1} and rGO _{Na- B- H2} Showed higher thermal stability, which was higher than the values for the GO and rGO _H comparative samples. This improvement was achieved due to better graphitization and deoxygenation resulting from the improved van der Waals force between the layers of the rGO sheet produced. TGA data of rGO _{Na - H3} and rGO _{Na - H4} were also provided in FIG.

rGO _{Na- B1} and rGO _{Na- B- H2} The degree of reduction of the films was measured by their hydrophobicity. Figure 10c is a GO, rGO _H, shows the wettability of rGO _{-B1 Na} and _Na rGO _{-B- H2} sample. The water contact angles of GO, rGO _H , rGO _Na-B1 and rGO _{Na- B- H2} thin films were 48.3 °, 80.9 °, 95.6 °, and 98.9 °, respectively (FIG. Apparently, rGO _{Na -B1} and rGO _{Na H2 -B-} The surface had higher hydrophobicity, which indicated a higher degree of reduction and a more complete removal of the oxygen content. The prepared product was characterized to confirm the preparation of single or multiple layers of rGO sheets. Atomic force microscopy (AFM) was first used to characterize the topographic heights of rGO _{Na -B1} and rGO _Na-B-H2 sheets on mica substrates (Fig. 13 (a) and (b)). The line scan of the height profile showed ~ 1.04 nm and ~ 0.91 nm mean terrain height, which was consistent with the typical height of the reported single layer graphene. A scanning electron microscope (SEM) was used to investigate the morphology of the rGO sheet produced. GO, pre-produced rGO _{Na- B1} and rGO _{Na- B- H2} And a representative SEM image of the rGO _H sample are shown in Fig. rGO _{Na - H3} and rGO _{Na - H4} And an SEM image of graphite (Fig. 14 (a) - (c)).

The rGO film is generally obtained on a membrane filter by vacuum filtration of a reduced rGO dispersion. However, the dispersion of the rGO sheet in solution is much more complicated than the usual GO. Recently, researchers have proven that strong GO papers are manufactured using similar filtration strategies. In order to make the obtained GO film conductive, it is necessary that the additional reduction process involves annealing under exposure to hydrazine vapor or HI-AcOH vapor and / or inert conditions. However, hydrazine and HI-AcOH vapor alone are not sufficient to achieve optimum reduction and require relatively high temperatures only by annealing. Furthermore, Feng et al. Recently reported that by using Na-NH ₃ as a reducing agent, the GO film can be easily converted into a uniform rGO film, which requires a very low temperature (-78 ° C). The process is effective but not environmentally friendly due to the need for low temperatures (-78 ° C) and the difficulty of handling NH ₃ . Importantly, using the Na-B and Na-BH systems used as reducing agents in the process of the present invention, the GO film can be easily converted into a homogeneous rGO film within a few minutes at room temperature (Fig. 15 (a) (G), Figs. 16 and 17]. The present application enables highly effective reduction and rapid deoxygenation of the solvated radical anions and complexes with said electrons under mild conditions and is able to obtain optimal recovery of the graphene-conjugate structure. Room temperature solution reduction processes are particularly important for graphene-based flexible stretchable conductive electrodes, and different pattern types can be easily processed at room temperature. To accomplish the present invention, a GO thin film or paper was first prepared by a vacuum filter of GO dispersion through a nitrocellulose membrane. The GO film was then transferred onto polyethylene terephthalate hydrochloride (PET) and dipped directly into the dark blue solution prepared (Fig. 15 (a)]. The brown GO film quickly changed to black within a few minutes in the solution. The black rGO film was taken out, washed with de-ionized water, and dried at room temperature (FIGS. 16 and 17). Conventional solution-based reduction of the GO using this solution as a reducing ink first provides a significant opportunity for the generation of a pre-designed conductive rGO pattern / track to facilitate the application of rGO-based devices. As shown in Figs. 15 (a) to 15 (g), designed rGO patterns (SKKU and line) were produced by this approach. By application of the two solution systems (Na-B and Na-BH), we have obtained rGO and N-doped rGO sheets. By controlling the Na-B and Na-BH solution systems, an rGO pattern with variable resistance could be generated. The sheet resistance of the rGO film is another important parameter for evaluating whether the? -conjugated system is restored in the rGO film. Figures 15 (a) to (g) show a series of rGO patterns using Na-B and Na-BH solution systems. The resulting average surface resistances of the rGO patterns were 200 5 Ω per square and 130 5 Ω per square for the Na-B and Na-BH solution systems, respectively (FIGS. 15 (c), (d) , (g)]. Significantly, low surface resistivities of ~ 130 Ω per square and ~200 Ω per square were achieved respectively in thin films (thickness ~ 4 μm) of N-doped rGO and rGO, which were obtained from solution-produced rGO films (Fig. 15 (c), (d), (f), (g), and Table 2 below).

[Table 2]

The surface resistivities of the pellets of rGO _{Na -B1} and rGO _{Na- B- H2 produced} were ~ 9 Ω per square and ~ 5 Ω per square at thickness ~ 11 μm, respectively (Table 2). The prepared rGO _Na-B1 and rGO _{Na- B- H2} The low surface resistivity observed in the films was consistent with the highest degree of deoxygenation and graphitization. This strategy is a very important milestone in advancing the electronics industry. The present invention relates to the use of rGO _{Na -B1} and rGO _{Na- B- H2} by controlled chemical transformation of GO films in Na-B and Na- Thin film can be formed gradually, which is very clean, safe, super-fast, and convenient. The present application can be used in many areas including membranes, anisotropic conductors, supercapacitors, and electrocatalytic oxygen reduction reactions (ORRs). Successful formation of graphene and N-doped graphene films from GO films and GO coatings by direct immersion in Na-B and Na-BH solutions has great potential in many applications such as sensors, neuroprosthetic devices And can lead to the development of a new era of antistatic coatings with low surface resistance, excellent thermal and chemical stability, water resistance and low production costs.

In conclusion, by applying a treatment with a system comprising a Na-B and Na-BH solution with an active solvated radical anion having an electron as a high reducing agent and mixed with a complex, the present invention provides the lowest oxygen &Lt; / RTI &gt; has developed a simple and effective method for producing graphene and N-doped graphene structures having a content (13.9 and 16.2 C / O ratios respectively). Furthermore, the present invention was able to control the degree of reduction with N-doping in the rGO sheet at room temperature. We will use this approach to directly reduce GO thin films with rGO and N-doped rGO films with combined low surface resistivity of ~ 200 Ω per square and 130 Ω per square with film thickness ~ 4 μm, respectively Proved to be possible. On the other hand, the surface resistivities of pellets of the prepared rGO _{Na -B1} and rGO _{Na- B- H2} were ~ 9 Ω per square and ~ 5 Ω per square, respectively, in thickness ~ 11 μm. We have demonstrated an alternative to in situ rGO and N-doped rGO fabrication, which is a very unique and easy procedure. In addition, the simplicity of the method and the room temperature process have demonstrated the possibility of mass production of rGo, and N-doped rGO sheets, and thin films on PET substrates. The Na-B and Na-BH solution systems used as inks can be directly employed in solid GO molds to produce high quality in-situ multifunctional rGO-based composite structures that are not N-doped or N-doped. Thus, this approach provides great flexibility in the fabrication of N-doped or non-doped graphene films and novel graphene-based materials and devices. The inexpensive and simple patterning process is also very important for future applications such as future nano-electrons and flexible electronics, antistatic coatings, electrochemical devices and conductive nanocomposites.

The foregoing description of the disclosure is exemplary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents are included in the scope of the present invention .

Claims (9)

A metal, and a photosensitizer to ionize the mixture to form a reducing agent;
Adding graphene oxide to the mixture in which the reducing agent is formed to reduce the graphene oxide to form reduced graphene oxide
&Lt; / RTI &gt;
The method according to claim 1,
Further comprising adding hydrazine as a reducing agent to the mixture prior to irradiating the light.
The method according to claim 1,
Wherein the metal comprises one selected from the group consisting of Na, Li, K, and combinations thereof.
The method according to claim 1,
Wherein the photosensitive agent comprises benzophenone.
The method according to claim 1,
Wherein the reducing agent formed by the ionization produces a solvated radical anion or a metal hydrazide complex.
The method according to claim 1,
Wherein the ionization is carried out at a temperature of from 0 캜 to 100 캜.
3. The method of claim 2,
Wherein the reduction of the graphene oxide and the simultaneous N-doping are carried out by the hydrazine additionally added.
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