KR101442061B1 - Superhydrophobic nano-graphene and method for preparing same - Google Patents

Abstract

The present invention relates to a flexible superhydrophobic nanographene for a transparent electrode which has a 3D nanonetwork structure in a lotus petal surface shape including a plurality of projections. Each of the projections has a height of 1-5 μm, a width of 10-50 μm, and a contact angle of 150-170°. According to the present invention, the superhydrophobic nanographene is transparent, and can usefully be used as a flexible device for a transparent electrode.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superhydrophobic nano-graphene,

The present invention relates to a superhydrophobic nano-graphene and a method of manufacturing the same.

Graphene is a two-dimensional sheet of carbon atoms and has received much attention due to its excellent properties. In addition to the well-known superior properties of graphene, such as its high electrical / thermal conductivity, excellent mechanical strength and light transmittance, water repellency, in particular in addition to the transparent electrodes in various non-wetting electronic devices, also includes magnetic cleaning, anti-fogging and anti- And so on.

Recently, efforts have been made to obtain a hydrophobic graphene surface by using low surface energy with appropriate illumination of graphene. For example, reduced graphene oxide paper has been found to have an artificial superhydrophobicity with a contact angle of 150 [deg.], Which is achieved through appropriate chemical composition and geometric characteristics thereof. However, no studies have been reported that include a lotus leaf-like superhydrophobic graphene surface with non-wetting properties. This seems to be due to the difficulty of configuring the complex dual-scale illumination of selected dimensions (micro / nanoscale) using a 2D graphene sheet of planarity. Further, yes from a recent study on the wettability of the pin, a graphene thin layer is yes exhibits a wet transmittance (wetting transparency) due to atomic-scale thickness of the fin, SiO ₂ or the number of hydrophilic semiconductor such as GaN - compatible flat base It has been found that it is difficult to change the wettability of the substrate by simply coating a few layers of graphene. At least four to six layers of graphene are required to impart hydrophobicity to the plane of the underlying substrate, but the intrinsic conductivity of graphene decreases with increasing thickness. Thus, it is difficult to realize a highly conductive hydrophobic film for use in a transparent electrode having water repellency. Indeed, the empirically obtained static contact angle (CA) of the epitaxial graphene is only 92 °, indicating a slight hydrophobicity, while achieving through surface roughness due to micro / nano-pores present between the layers The irregular stack of reduced graphene oxide has a higher CA of 127 [deg.]. Therefore, in order to realize a graphene-based superhydrophobic device, it is important to combine a more appropriate surface roughness with a lower surface energy.

Among the many graphene synthesis approaches, CVD growth is a promising method for producing high quality large scale graphenes on a wide range of substrates. CVD growth of graphene on copper foil is particularly advantageous because it allows the creation of optimal graphenes with controllable thickness and good conductivity. A problem with the CVD growth of graphene on the copper foil in terms of surface roughness is that the shape of the single crystal graphene is limited to the 2D plane of the flat copper film surface. Developing graphene fabrication methods that can have various forms and dimensional scalability while maintaining conductivity in 2D flat sheet form is important in applying graphene to non-wetted electronic devices that are protected from future contact with water . From this point of view, the copper oxide can provide an appropriate path depending on the morphological change of the copper substrate through the change of the oxidation state from Cu (0)? CuO (II), Cu ₂ O (I). In addition, thermal reduction of metal oxides using hydrogen with well-known mechanisms has often been used to fabricate active metal catalysts that allow for additional morphological changes. Thus, a controlled synthesis method of definite metal oxide and metal structures provides a new method for obtaining graphene having a custom shape through the form of an adjustable copper catalyst.

It is an object of the present invention to provide a process for the preparation of superhydrophobic graphene by simulating the characteristics of a lotus leaf on the surface of CVD growth graphene through superhydrophobic graphene and the oxidation state change of the copper substrate in relation to the morphological change in the high temperature annealing and cooling cycle And a method for manufacturing the same.

In order to achieve the above object,

A flexible polyhydrophobic nano graphene for a transparent electrode having a 3D nano network structure having a lotus leaf surface shape including a plurality of projections,

The protrusions having a height of 1 to 5 mu m and a width of 10 to 50 mu m,

Hydrophobic nano-graphene having a contact angle of 150 to 170 DEG.

In addition,

(1) heating a copper substrate to produce a CuO (II) nanowhisker supported on a copper substrate;

(2) annealing a CuO (II) nanowhisker supported on the copper substrate to reduce CuO (II) to produce a 3D nanostructure of Cu (0) on the copper substrate; And

(3) annealing the 3D nanostructure of Cu (0) under H ₂ / CH ₄ to produce graphene having 3D nano network structure of lotus leaf surface shape by chemical vapor deposition (CVD) , And a method for manufacturing a flexible, superhydrophobic nano-graphene for a transparent electrode.

The hydrophobic nano-graphene according to the present invention has transparency, has a low surface energy with a suitable surface roughness, has a high water contact angle, and thus can be effectively used as a flexible element for a transparent electrode.

In addition, the process for preparing a super-hydrophobic nano-graphene laminate according to the present invention can be usefully used for producing transparent superhydrophobic nano-grains having a high water contact angle.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic representation of the steps of a) a method of producing a superhydrophobic nano-graphene according to an embodiment of the present invention, and b) through d) XRD results.
FIG. 2 is a SEM photograph of various shapes of graphene nanostructures grown by various processing conditions, and a typical CVD-grown graphene Raman grown on CH ₄ / H ₂ gas at 1000 ° C and 24/10 sccm Lt; / RTI >
Fig. 3 is an SEM photograph of a superhydrophobic nano-graphene according to an example of the present invention having a 3D nano network structure of a lotus leaf and a lotus leaf surface, and optical photographs of surface water droplets of various substrates.

The superhydrophobic nano graphene according to the present invention has a 3D nano network structure with a lotus leaf surface shape including a plurality of projections.

The 3D nano network structure includes a plurality of protrusions, such as protrusions on the surface of a lotus leaf, wherein the protrusions have a height of 1 to 5 mu m and a width of 10 to 50 mu m, preferably 10 to 20 mu m, Lt; RTI ID = 0.0 > um. ≪ / RTI >

The protrusions include a plurality of wrinkles on the surface, wherein the wrinkles have a nanometer size.

The hydrophobic nano-graphene according to the present invention may exhibit superhydrophobicity due to the presence of wrinkles on the surfaces of the protrusions and protrusions, and the water contact angle may be 150 to 170 degrees, preferably 155 to less than 170 degrees.

The superhydrophobic nano-graphene according to the present invention can exhibit a low surface resistance of 200? /? To 1.2? / ?.

The ultra-hydrophobic nano-graphene according to the present invention

(1) heating a copper substrate to produce a CuO (II) nanowhisker supported on a copper substrate;

(2) annealing a CuO (II) nanowhisker supported on the copper substrate to reduce CuO (II) to produce a 3D nanostructure of Cu (0) on the copper substrate; And

(3) annealing the 3D nanostructure of Cu (0) under H ₂ / CH ₄ to produce graphene having 3D nano network structure of lotus leaf surface shape by chemical vapor deposition (CVD) , And a manufacturing method of a flexible superhydrophobic nano-graphene for a transparent electrode.

In step (1), a copper substrate is heated to produce a CuO (II) nanowhisker supported on a copper substrate.

The copper substrate may be a copper plate or a copper foil, or a commercially available copper foil may be used. The thickness range of the copper base material is not particularly limited, but may be 1 to 300 占 퐉, 5 to 200 占 퐉, 10 to 100 占 퐉.

The CuO (II) nanowhisker can be produced by heating the copper substrate under air (oxygen) conditions, and if necessary, coating the copper substrate with a CuCl ₂ solution before heating the copper substrate May be further included.

Examples of the coating method include spin coating, die coating, gravure coating, micro gravure coating, comma coating, roll coating, dip coating, spray coating, drop casting and the like, preferably spin coating or spray coating .

The heating may be performed at 200 to 1000 ° C, preferably 400 to 800 ° C, for 0.3 to 15 hours, preferably 2 to 12 hours.

Heating the copper foil in an air condition induces partially agglomerated metal precursors on the surface of the copper foil and then an oxidation reaction of the copper substrate takes place to form a CuO (II) nanowhisker protruding from the copper surface.

The diameter and height of the CuO (II) nanowhisker can be controlled by heating conditions, and the higher the heating temperature, the longer the CuO (II) nanowhisker having a larger diameter can be formed.

Among the three oxidation states (CuO, Cu ₄ O ₃ , and Cu ₂ O), CuO and Cu ₂ O are known to be more stable compounds, and CuO has a lower reduction activation energy (CuO: 15 kcal / mol, Cu ₂ O: since 27 kcal / mol) may be brought more easily reduced than the Cu ₂ O, yes, it is preferable to use the Cu ₂ O instead of CuO Cu as a catalyst for the growth pin. In addition, CuO has a melting point higher than that of Cu ₂ O (1,446 ° C and 1,235 ° C, respectively), allowing the shape to continue during the reduction to Cu.

In step (2), CuO (II) is reduced by annealing a CuO (II) nanowhisker supported on the copper substrate to produce a 3D nanostructure of Cu (0) located on the copper substrate.

The annealing is performed by heating under hydrogen conditions, and the heating may be performed at 600 to 1400 ° C, preferably 950 to 1,050 ° C, for 0.1 to 2 hours, preferably 0.2 to 1 hour. If the heating temperature is lower than 600 ° C, CuO (II) may not be completely reduced, which is undesirable. If the heating temperature is higher than 1,400 ° C, the melting point of CuO (II)

The annealing process may further be roughened at room temperature to anneal the CuO (II) nanowhisker supported on the copper substrate to reduce CuO (II) to form Cu (II) 0) can be produced, and the 3D nano structure of Cu (0) may have a lotus leaf surface shape.

In step (3), the 3D nanostructure of Cu (0) is annealed under a condition of H ₂ / CH ₄ to produce graphene having 3D nano network structure of lotus leaf surface shape by chemical vapor deposition (CVD).

The annealing of the Cu (0) to the 3D nanostructure may be performed by heat treatment at 600 to 1,000 ° C. for 5 to 60 minutes, preferably 10 to 30 minutes.

When graphene is prepared by chemical vapor deposition (CVD) after the annealing of the 3D nanostructure of Cu (0), graphene is formed on the surface of the 3D nanostructure of Cu (0) having a lotus leaf surface shape, As a result, graphene having a 3D nano network structure of lotus leaf surface shape is produced.

The method for producing a superhydrophobic nano graphene according to the present invention is characterized in that after the steps (1) to (3), the graphene having the 3D nano network structure prepared in the step (4) (PDMS) substrate.

In the step (4), a laminate of PDMS / graphene / Cu base material is formed by laminating a polydimethylsiloxane (PDMS) base material on the graphene having the 3D nano network structure manufactured in the step (3) Calcining at 60 to 200 ° C for 2 to 8 hours, and then removing the Cu substrate using an aqueous solution of (NH ₄ ) ₂ SO ₅ .

The hydrophobic nano-graphene prepared by the above method may have a water contact angle of 150 to 170 degrees, preferably 155 to less than 170 degrees.

FIG. 1 (a) schematically shows a step of preparing a nanoparticle of CuO (II) on a substrate and a step of producing a 3D nanostructure of Cu (0) in a process for producing a superhydrophobic nano-grapin according to the present invention The drawings are shown.

Referring to FIG. 1A, first, in step (I), a copper substrate is heated in an oxygen / air atmosphere at 600 DEG C for 30 minutes to produce a CuO (II) nanowhisker supported on a copper substrate. Thereafter, in step (II), a 3D nanostructure of Cu (0) is prepared on a copper substrate by annealing a CuO (II) nanowhisker by heating to 1,000 ° C. in a hydrogen atmosphere.

As another example of the manufacturing method, a CuO (II) nanowhisker structure is prepared by spin-coating a commercially available copper foil with a solution of CuCl ₂ and heating it to 400 ° C. in an air atmosphere for 2 hours, The resulting CuO (II) nanowhisker structure is heated to 1000 ° C. for 30 minutes under hydrogen conditions, and then cooled to room temperature to produce a modified 3D network having various shapes on the copper substrate.

Thus, when a 3D nanostructure of Cu (0) is produced on a copper substrate, graphene can be formed on the surface of the 3D nanostructure of Cu (0) by chemical vapor deposition (CVD) using CH ₄ .

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments for better understanding of the present invention. However, the following examples are intended to illustrate the present invention, but the scope of the present invention is not limited to or by the following examples.

Example

≪ CuO / Cu (OH) ₂ Synthesis of >

A copper foil (Alfa Aesar Co.) having a thickness of 25 μm was washed with acetone and deionized water for 10 minutes using an ultrasonic generator, and then a basic solution composed of 1: 1 2 M NaOH and 0.15 M (NH ₄ ) ₂ SO ₅ Lt; / RTI > After 30 minutes, the prepared sample was washed with deionized water.

<Chemical vapor deposition of graphene on Cu>

The sample was placed in a quartz tube (Scientech) and the temperature in the heating zone was increased to 1000 ° C in a H ₂ atmosphere at a pressure of 0.9 torr. When the temperature reached 1,000 占 폚, the heating region was moved to the sample. Next, the temperature was reduced to 740 占 폚 and then increased to 1000 占 폚. After reaching 1000 캜, 24 sccm of CH ₄ gas was flowed for 25 minutes under a pressure of 1 torr. Finally, the sample was rapidly cooled to room temperature while flowing H ₂ and CH ₄ gas under a pressure of 1 torr.

< Grapina  Delivery>

A polydimethylsiloxane (PDMS) mold was prepared using a SYLGARD 184 silicone elastomer kit (Dow Corning). The SYLGARD 184 silicone elastomer was mixed with the curing agent in a ratio of 10: 1. The mixture was mixed by roll for 30 minutes. When the mixture is heated at an appropriate temperature, a crosslinking reaction occurs between the vinyl group contained in SYLGARD 184 and the silicon hydride contained in the curing agent, resulting in thermally and chemically stable and transparent PDMS. The graphene on the copper was molded using PDMS, and the bubbles in the sample were removed in a vacuum oven for 1 hour. The PDMS / graphene / Cu was then baked in an oven at 80 DEG C for 4 hours. Subsequently, the copper foil was removed by suspending the fully cured PDMS / graphene / Cu sample in an aqueous solution of 1 M (NH ₄ ) ₂ SO ₅ for 2 hours. Finally, the obtained sample was heat-treated at 80 캜 overnight. Through this process, the grown graphene on the copper surface was transferred to the prepared PDMS substrate.

Experimental Example

The morphology of the sample was observed through field emission SEM (Nova Nano-SEM 230, 15 kV). The quality of graphene was confirmed using Raman spectroscopy (WITec, alpha300R; excited by 532 nm laser). (High-power X-ray diffractometer of 10 DEG to 80 DEG) (Rigaku). The heat treatment was carried out using a Lenton 1,200 ° C vacuum tube furnace. The contact angle was measured at ambient temperature using a drop shape analysis system (DSA100, Kruss, Germany). The average CA and SA values were obtained by measuring 10 different positions of the same sample. The sheet resistance of the graphene transferred onto the PDMS substrate was measured using a standard four-point probe method (Dasol Eng, FPP-RS8, pin-spacing 1 mm, pin-radius 100 μm). Five points were measured and averaged for each sample.

<SEM and XRD>

1 (b) to 1 (d) show SEM photographs of the copper foil and XRD results of the samples in the respective states.

As shown in the photograph in Fig. 1 (b), the commercial copper foil has a polycrystalline surface texture. SEM photographs show orientation textures having grain boundaries extending parallel to each other at intervals of several to several tens of micrometers and covering the surface of the film. Generally, the surface of copper becomes more roughened during the high temperature annealing and the surface reconstruction process during growth.

Figure 1C shows TEM images of individual CuO (II) nanowhiskers and SAED patterns of indexed nanowhiskers in diffraction spots of monoclinic CuO. FIG. 1 (c) shows that the surface of the copper foil was changed into a nanowhisker due to the formation of copper oxide crystals after the heat treatment in an oxygen environment. The diameter and length of the vertically aligned nanowhiskers on the copper substrate determine the final shape of the graphene formed by the chemical vapor deposition. Referring to the SAED pattern, the XRD spectrum of one strong peak corresponding to the (200) plane of Cu (0) and the (-111) cubic CuO (II) phase having a small amount of crystalline Cu ₂ O at 50 °, , (111) and (220), it was confirmed that CuO was grown on the surface of the copper base material through the XRD spectrum.

It was confirmed that there was an unoxidized substance under the copper substrate through the peak at 50 ° which is the same position as the strongest peak of Cu.

FIG. 1D shows the SEM and XRD results of copper samples immediately after annealing under hydrogen conditions (before graphene growth started).

It has been known that CuO and Cu ₂ O can be reduced at a temperature of about 200 ° C. or more by heat treatment under H ₂ conditions and the vacancies of O atoms generated by the insertion of hydrogen into the lattice of the metal oxide are reduced to metal oxide It is known to be important in the mechanism. However, in the present invention, in order to completely reduce the CuO of the CuO (II) nanowhisker, reduction was performed at 1,000 ° C under an H ₂ gas, thereby reducing CuO to metal Cu. As shown in FIG. 1D, it was confirmed that CuO was completely returned to Cu having almost single crystal characteristics through XRD. Also, at high temperature annealing, the alignment form of the copper oxide nanowhisker was disturbed and its shape apparently changed. That is, it is judged that the sharp end portions of neighboring nanowhiskers are collapsed and adhered to each other to produce a 3D nano structure of Cu (0) in a controlled shape.

<Observation through SEM>

FIG. 2 shows SEM images of various shapes of graphene nanostructures grown by various processing conditions, and representative CVD-grown grains grown on CH ₄ / H ₂ gas at 1000 ° C and 24/10 sccm of reduced Cu Raman spectra are shown.

Cu (0) Yes disclosed in 3D nanostructure of the pin growth has reached the growth temperature and CH ₄ is starts immediately after the introduction of a chemical vapor deposition chamber, the graphene is a 3D nanostructure of Cu (0) during the growth process, It is nanostructured according to the surface morphology. Therefore, the CVD-grown graphene on the Cu frame has a unique 3D structure with a lateral dimension of several tens of micrometers, as shown in Figs. 2A to 2C.

It has been found that as the copper surface is flat and the reduction temperature and heat treatment time in the H ₂ environment are increased, a more smooth surface graphene film can be obtained, which indicates that the high temperature reduction of CuO is a very low melting It is believed that the temperature causes the newly formed sharp copper tips to collapse and coalesce.

Thus, by simply changing the reaction period and temperature, the shape of the 3D graphene was successfully converted from the nanoporous graphene structure (a in Fig. 2 and b in Fig. 2) to the graphene film in the flower-shaped huge domain (c in Fig. 2) Respectively.

Figure 2d is the Raman spectrum of 3D graphene (corresponding to c in Figure 2) grown on a 3D copper substrate, identified in at least 10 different regions. The very small D band at 1350 cm ^-1 indicates that there is not a significant number of graphene defects at the edges, despite the generation of much free space in the 3D nanoframe. E _2g 3D graphene produced by a band at 1580 cm ^-1 due to symmetric doubly degenerate photons and a very strong 2D band at 2700 cm ^-1 have high quality. The full-width-at-half-maximum (FWHM) was about 77 cm ^-1 . The ratio of I _D / I _G and I _2D / I _G of graphene grown on reduced graphene is 0.17 and 6.29, respectively, which represents a single layer of high quality graphene in a 3D nanoframe. In particular, a low I _D / I _G value similar to the I _D / I _G value (0.56) of the 2D graphene grown on the planar Cu substrate is indicative of the superior quality of the graphene having the 3D nanonetwork structure fabricated on the CuO 3D nanostructure Support the fact.

&Lt; SEM and contact angle measurement of superhydrophobic nano-graphene >

FIG. 3 is a SEM photograph of a superhydrophobic nano-graphene according to an embodiment of the present invention having a 3D nano network structure of a lotus leaf and a lotus leaf surface, and various substrates, namely, three kinds of hydrophilic Cu substrates and three hydrophobic poly Is an optical photograph of water droplets on the surface of a dimethylsiloxane (PDMS) substrate.

Figures 3 (a) and 3 (b) show SEM images of the surface of the lotus leaf and the upper surface of the lotus leaf morphology graphene grown on copper, respectively. The photographs inserted in FIGS. 3 (a) and 3 (b) are photographs of water droplets on each substrate, and the water droplets have a very small contact angle on the substrate. In the inset picture of FIG. 2 (b), the film has some translucency due to light scattering by many voids included in the 3D structure of graphene.

As shown in Fig. 3 (a), the surface of the lotus leaf has protrusions having a height of about 10 to 20 mu m and a width of 10 to 15 mu m, and these protrusions include nanometer-scale wrinkles. The superhydrophobic and magnetic cleaning properties of the lotus leaf are due to the layered micro- / nanostructures on wax coated low surface energy substrates.

Therefore, the superhydrophobic nano-graphene according to the present invention has double scale (micro- and nano) protrusions similar to the protrusions included in the lotus leaf by controlling the oxidation and reduction conditions in the production.

(E) graphene formed on the untreated copper foil, and (e) a lotus leaf protrusion shape formed on the copper foil. It is a photograph of a droplet on a graphene. Raman spectra confirmed that the graphene film in the d sample of FIG. 3 and the sample of FIG. 3 was a single layer.

Surprisingly, despite the coating of the hydrophobic graphene film, (d) the contact angle of the graphene / Cu film did not show a noticeable increase compared to (c) the untreated copper film. This is because the atomic scale thickness of the graphene film can not significantly change the wettability of the Cu substrate. However, 57.2 [deg.] Of planar graphene on the untreated copper thin film Compared to the contact angle, the contact angle of graphene, including the shape of the lotus leaf protrusions produced on the hydrophilic copper substrate, increased to 79.8 degrees. Considering that the surface wettability is determined by two main factors, that is, surface roughness and surface energy, together with the wet transparency of the single layer graphene film, the fact that the contact angle of graphene including the shape of the lotus leaf protrusions on the hydrophilic copper substrate is improved This is because graphene has a 3D structure.

In Figs. 3 (f) to 3 (h), a photograph comparing the wettability of the three hydrophobic bases is shown. The contact angle of the water droplet on the surface of the 3D graphene on the PDMS substrate is as high as 156.2 deg., Which is much larger than that of the control sample (flat PDMS, g in Fig. 3, 112.2 deg.) And lotus leaf (148.2 deg.

The process of laminating the 3D graphenes on the PDMS substrate comprises laminating a polydimethylsiloxane (PDMS) substrate on a graphen having a 3D nano network structure formed on a copper substrate to form a laminate of PDMS / graphene / Cu substrate type And then removing the copper substrate after the firing. It was observed that the surface of the PDMS was changed to hydrophilic when the copper substrate was etched in ammonium peroxodisulfate ((NH ₄ ) ₂ SO ₅ ) solution for one day. Thus, in order to restore the inherent hydrophobicity of PDMS, we heat the control PDMS sample and the graphene coated PDMS sample overnight on a hot plate or treat the sample with silane. After chemical modification of the surface by heat treatment or silane treatment, the surface of graphene, including the shape of lotus leaf protrusions, was clearly hydrophobic with a contact angle of 156.2 °, while the corresponding values of PDMS were 112 °.

Therefore, the superhydrophobic nano graphene having the 3D nano network structure according to the present invention maintains a surface resistance of 1.2 k? / Square, so that it is suitable to be used as a heat line even after the silane treatment as a heat ray having a curved surface shape. This shows that a superhydrophobic 3D graphene electrode can be fabricated on a flexible substrate.

As described above, it is possible to obtain a 3D nano network structure including a shape of a lotus leaf protrusion having a water repellent property, which is produced through a shape change through the process of CuO reduction under the conditions of oxidation of a flat copper substrate and subsequent CVD growth of graphene Since the contact angle of the superhydrophobic nano-graphene is 156 째 or more and the electrical resistance is as low as 1.2 ㏀ / □, it can be usefully used in electronic devices having a super hydrophobic property while maintaining electrical characteristics even in a large scale manufacturing.

Claims (10)

A flexible polyhydrophobic nano graphene for a transparent electrode having a 3D nano network structure having a lotus leaf surface shape including a plurality of projections,
The protrusions having a height of 1 to 5 mu m and a width of 10 to 50 mu m,
Superhydrophobic nano-graphene with a contact angle of 150 ° to 170 °.
The method according to claim 1,
Wherein the protrusions comprise a plurality of wrinkles on the surface.
The method according to claim 1,
A superhydrophobic nano-graphene having a surface resistance of 200? /? To 1.2? / ?.
(1) heating a copper substrate to produce a CuO (II) nanowhisker supported on a copper substrate;
(2) annealing a CuO (II) nanowhisker supported on the copper substrate to reduce CuO (II) to produce a 3D nanostructure of Cu (0) on the copper substrate; And
(3) annealing the 3D nanostructure of Cu (0) under H ₂ / CH ₄ to produce graphene having 3D nano network structure of lotus leaf surface shape by chemical vapor deposition (CVD) , A method for producing a flexible, superhydrophobic nano-graphene for a transparent electrode.
5. The method of claim 4,
Wherein the heating of step (1) is performed at 200 to 1,000 ° C. for 0.3 to 15 hours.
5. The method of claim 4,
Wherein the annealing in step (2) is performed by heat treatment at 600 to 1400 占 폚 for 0.1 to 2 hours under hydrogen conditions.
5. The method of claim 4,
Wherein the annealing in step (3) is performed by heat treatment at 600 to 1000 占 폚 for 5 to 60 minutes.
5. The method of claim 4,
In the above step (1) The method of producing a superhydrophobic nano-graphene further comprising the step of coating a CuCl ₂ solution to the copper substrate before the heat of the copper substrate.
5. The method of claim 4,
Following step (3), the method further comprises: (4) transferring graphene having the 3D nano network structure produced in step (3) to a polydimethylsiloxane (PDMS) &Lt; / RTI &gt;
10. The method of claim 9,
In the step (4), a layered product of PDMS / graphene / Cu base material is formed by laminating a polydimethylsiloxane (PDMS) base material on the graphene having the 3D nano network structure manufactured in the step (3) Firing at 60 to 200 캜 for 2 to 8 hours, and then removing the Cu substrate using an aqueous solution of (NH ₄ ) ₂ SO ₅ .

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