JP7203850B2 - Reduced graphene oxide, reduced graphene oxide-functional material composite, and method for producing the same - Google Patents

Description

The present invention relates to a method for producing reduced graphene oxide (r-GO) or a reduced graphene oxide-functional material composite, and more specifically, electrochemically reducing graphene oxide. and a method for producing a reduced graphene oxide-functional substance composite by reducing the composite of graphene oxide and the functional substance.

Graphene is a material with extremely stable electrical, mechanical, and chemical properties, and is used in various fields of application, and many studies have been conducted on it.

Graphene oxide has some of the properties of graphene, and has the advantage of being easily dispersed in solvents and being inexpensive, so much research has been done. On the other hand, graphene oxide has a drawback of being inferior to graphene in electrical conductivity. However, electrical conductivity can be improved by chemically or electrochemically reducing graphene oxide to produce reduced graphene oxide. Therefore, reduced graphene oxide has attracted interest as an electrode candidate material in fields such as electrodes used in secondary batteries and supercapacitors, electrochemical electrodes used in electrochemical sensors, and electrodes used for chemical reaction catalysts, and research has been conducted. It is done.

Further, in recent years, research has been actively conducted to add functionality to the properties of reduced graphene oxide to further increase its utility. Specifically, there is an example in which a functional substance is further introduced into the reduced graphene oxide to exhibit properties and functionality unique to the reduced graphene oxide at the same time.

However, a composite of reduced graphene oxide and a functional substance has a problem that the functional substance is activated on the surface of the reduced graphene oxide. Therefore, in the present invention, the functional substance is included not only on the surface of the reduced graphene oxide but also in the interior thereof, and the functional substance is activated also in the reduced graphene oxide. We present a method for producing reduced graphene oxide-functional substance composites that can maximize the .

An object of the present invention is to provide a production method for reducing graphene oxide or a graphene oxide-functional substance composite to improve electrical conductivity.

Another object of the present invention is to provide a manufacturing method for improving the properties of reduced graphene oxide or reduced graphene oxide-functional material composites.

Still another object of the present invention is to provide a method for rapidly preparing reduced graphene oxide or reduced graphene oxide-functional material composites with improved properties.

To achieve the above object, a method for preparing reduced graphene oxide according to an embodiment of the present invention includes dispersing graphene oxide in a solvent to form a graphene oxide dispersion; forming a graphene oxide mixture by supplying a solution of; coating the graphene oxide mixture on a conductor and drying it at a predetermined temperature to form a graphene oxide thin film; and forming the graphene oxide thin film. immersing the resulting conductor in an electrolyte in the temperature range of 35-70° C. to electrochemically reduce it to form reduced graphene oxide.

In one embodiment, the dispersion contains a solvent and 0.1 to 5% by weight of the graphene oxide.

In one embodiment, the predetermined solution contains a water-soluble polymer. Specifically, the water-soluble polymer includes polyvinylalcohol (PVA), polyacrylic acid (PAA), polyvinylpyrrolidone (PVP), polyethyleneglycol (PEG), and polyurethane (PU). , polytetrafluoroethylene (PTFE), and a polymer (Nafion) having a sulfonic acid group introduced into the polytetrafluoroethylene skeleton.

In one embodiment, the predetermined solution contains a solvent and 0.05 to 0.2% by weight of the polymer.

In one embodiment, the predetermined temperature in the step of forming the graphene oxide thin film is in the range of 50 to 80.degree.

In one embodiment, the concentration of the electrolyte in the step of forming the reduced graphene oxide ranges from 1 M to a saturated solution.

In one embodiment, the step of forming reduced graphene oxide includes forming a three electrode system including a reference electrode, a counter electrode and a working electrode. and electrochemically reducing the graphene oxide thin film.

According to one embodiment, a reduced graphene oxide produced by any of the above production methods is provided.

In addition, a method for producing a reduced graphene oxide-functional material composite according to an embodiment of the present invention includes dispersing graphene oxide in a solvent to form a graphene oxide dispersion; supplying a functional material and a predetermined solution to form a graphene oxide-functional material mixture; coating the graphene oxide-functional material mixture on a conductor and drying at a predetermined temperature to form graphene oxide- By forming a functional substance composite thin film, and electrochemically reducing the conductor on which the graphene oxide-functional substance composite thin film is formed by immersing it in an electrolyte in a temperature range of 35 to 70 ° C. and forming a reduced graphene oxide-functional substance composite.

In one embodiment, the graphene oxide dispersion comprises a solvent and 0.1 to 5% by weight of the graphene oxide.

In one embodiment, the functional material in the step of forming the graphene oxide-functional material mixture includes electrochemically active particles silicon (Si), titanium (Ti), vanadium (V), manganese (Mn ), iron (Fe), cobalt (Co), nickel (Ni), ruthenium (Ru), lead (Pb), Antimony Tin Oxide (ATO) and at least one of their oxides.

In one embodiment, the functional material in the step of forming the graphene oxide-functional material mixture is an electrochemically active compound, nickel Prussian blue (Ni-PB), ferrocene, ferrocene derivatives, quinones, quinone derivatives. , ruthenium amine complexes, osmium(I), osmium(II), osmium(III) complexes, metallocenes and metallocene derivatives.

In one embodiment, the functional material in the step of forming the graphene oxide-functional material mixture includes iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), palladium (Pd) and At least one of platinum (Pt) is included.

In one embodiment, the predetermined solution contains a water-soluble polymer. Specifically, the water-soluble polymer includes polyvinylalcohol (PVA), polyacrylic acid (PAA), polyvinylpyrrolidone (PVP), polyethyleneglycol (PEG), and polyurethane (PU). , polytetrafluoroethylene (PTFE), and a polymer (Nafion) having a sulfonic acid group introduced into the polytetrafluoroethylene skeleton.

In one embodiment, the predetermined solution contains a solvent and 0.05 to 0.2% by weight of the polymer.

In one embodiment, the predetermined temperature in the step of forming the graphene oxide-functional substance composite thin film is in the range of 50 to 80.degree.

In one embodiment, the concentration of the electrolyte in the step of forming the reduced graphene oxide-functional material complex is in the range of 1 M to a saturated solution.

In one embodiment, forming the reduced graphene oxide-functional material composite includes forming a three-electrode system including a reference electrode, a counter electrode and a working electrode, and It is characterized by electrochemically reducing a thin film.

According to one embodiment, there is provided a reduced graphene oxide-functional substance composite produced by any one of the above production methods.

According to the method for producing reduced graphene oxide or reduced graphene oxide-functional substance composite according to the present invention, graphene oxide or graphene oxide-functional substance composite is electrochemically reduced to improve electrical conductivity. .

In addition, according to the present invention, a method for electrochemically reducing graphene oxide or a graphene oxide-functional substance composite increases the active area per unit area, and reduces graphene oxide or reduced graphene oxide. - the properties of the functional substance complex can be maximized;

Further, according to the present invention, in the method of electrochemically reducing graphene oxide or graphene oxide-functional substance composite, the concentration of the electrolyte is reduced in the range of 1 M to the electrolyte saturated solution, and the temperature of the electrochemical cell is in the range of 35 to 70° C., reduced graphene oxide or reduced graphene oxide-functional substance composite can be rapidly produced.

1 is a flowchart illustrating a method for producing reduced graphene oxide of the present invention; 1 is a flow chart showing a method for producing a reduced graphene oxide-functional substance composite of the present invention; 1 is a conceptual diagram showing a graphene oxide-functional substance composite of the present invention. FIG. 1 is a conceptual diagram showing a reduced graphene oxide-functional substance composite of the present invention; FIG. 4 is a graph showing a cyclic voltammetry curve measured after reducing a graphene oxide thin film for a predetermined time by chronoamperometry; FIG. 2 is a graph showing the relationship between the time of electrochemical reduction of graphene oxide with 5M NaNO ₃ electrolyte at various temperatures and the measured charge capacity of graphene oxide. FIG. 4 is a graph showing voltage and current measured during reduction of a graphene oxide-functional material composite containing nickel Prussian blue by cyclic voltammetry; FIG. 4 is a graph of voltage and current measured after reducing graphene oxide-functional material composites containing nickel Prussian blue with various concentrations of NaCl and LiCl electrolytes by cyclic voltammetry; FIG. 1 is a graph showing voltage and current measured after reducing a graphene oxide-functional material composite containing silicon nanopowder by cyclic voltammetry; 4 is a graph showing voltage and current measured after reducing a graphene oxide-functional substance composite containing ruthenium oxide by chronoamperometry; 4 is a graph of voltage and current measured after reduction of a graphene oxide-functional substance composite containing lead oxide by cyclic voltammetry; 4 is a graph of voltage and current measured during reduction of a graphene oxide-functional material composite containing antimony tin oxide (ATO) by cyclic voltammetry; 1 is an electron microscope image measured after reduction of a graphene oxide-functional substance composite containing platinum nanoparticles by chronoamperometry; It is the result of Energy Dispersive X-ray Spectroscopy (EDX) of the sample of FIG. 11A.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, wherein the same reference numerals denote the same components throughout. In addition, in describing the embodiments disclosed in this specification, if it is determined that the specific description of the related known technology obscures the gist of the embodiments disclosed in this specification, that Detailed description is omitted. Furthermore, the accompanying drawings are merely for the purpose of making it easier to understand the embodiments disclosed herein, and the technical ideas disclosed herein are not limited by the accompanying drawings. It should be understood to include all modifications, equivalents or alternatives falling within the spirit and scope of the invention. As used herein, singular terms include plural terms unless specifically stated otherwise.

In the present invention, production of reduced graphene oxide or reduced graphene oxide-functional substance composite, in which graphene oxide or graphene oxide-functional substance composite is electrochemically reduced to improve electrical conductivity. Present a method.

In addition, in electrodes of electrochemical cells such as electrodes used in secondary batteries and supercapacitors, electrochemical electrodes used in electrochemical sensors, and electrodes for chemical reaction catalysts, the active electrode area per unit area is very important. . In addition, in secondary batteries and supercapacitors, an increase in the active electrode area involved in the reaction per given area leads to an increase in charge capacity.

Therefore, in the present invention, a method for electrochemically reducing graphene oxide or a graphene oxide-functional substance complex increases the active area per unit area, and reduces the reduced graphene oxide or the reduced graphene oxide- A method for producing reduced graphene oxide or reduced graphene oxide-functional substance composite is presented, which can maximize the properties of the functional substance composite.

FIG. 1A is a flow chart showing the method for producing reduced graphene oxide of the present invention, and FIG. 1B is a flow chart showing the method for producing the reduced graphene oxide-functional material composite of the present invention.

As shown in FIG. 1A, the method for producing reduced graphene oxide of the present invention comprises dispersing graphene oxide in a solvent to form a dispersion, then coating the dispersion on a conductor and drying it. By forming a thin film and electrochemically reducing it, reduced graphene oxide can be produced. Each process will be described below.

First, in step S100, graphene oxide and a solvent are prepared. A dispersion is prepared by adding graphene oxide to the prepared solvent. A content of the graphene oxide in the dispersion may be 0.1 to 5% by weight.

In one embodiment, when the content of the graphene oxide is less than 0.1% by weight, it is difficult to form a graphene oxide thin film, which will be described later, because the content of the graphene oxide is low.

On the other hand, when the content of the graphene oxide exceeds 5% by weight, the graphene oxide solution has a very high viscosity and is very difficult to handle.

Next, in step S200, a predetermined solution is supplied to the graphene oxide dispersion to form a graphene oxide mixture. A predetermined solution supplied to the graphene oxide dispersion is a solution containing a water-soluble polymer. Specifically, the polymer in the predetermined solution is a water-soluble polymer that enables formation of a coating film, and is mixed with graphene oxide to help form a graphene oxide thin film.

The water-soluble polymer in the predetermined solution serves as a binder for graphene oxide in a step of electrochemically reducing the graphene oxide thin film, which will be described later, and prevents loss of graphene oxide in the electrolyte.

The water-soluble polymer in the predetermined solution includes polyvinylalcohol (PVA), polyacrylic acid (PAA), polyvinylpyrrolidone (PVP), polyethyleneglycol (PEG), polyurethane (PU). ), polytetrafluoroethylene (PTFE), and a polymer (Nafion) having a sulfonic acid group introduced into the polytetrafluoroethylene skeleton.

Moreover, the predetermined solution may contain a solvent and 0.05 to 0.2% by weight of a polymer. If the content of the polymer is less than 0.05% by weight, it may be difficult to form a thin film in the step of forming a graphene oxide thin film, which will be described later. , the polymer coats the graphene oxide, which may hinder smooth electrochemical reduction of the graphene oxide.

Then, in step S300, a graphene oxide thin film is formed by coating the graphene oxide mixed solution on a conductor and drying it at a predetermined temperature. The conductor may be a material with good electrical conductivity and high chemical stability. Also, the conductor is coated with the graphene oxide thin film and used as a working electrode for electrochemically reducing the graphene oxide.

In one embodiment, dip coating, spin coating, screen coating, offset printing, inkjet printing, spraying, pad printing, knife coating, kiss coating, gravure coating, brushing, ultra-thickness coating, etc., are used to apply the graphene oxide to the conductor. Either sonic fine spray coating or spray mist spray coating is selectively performed, but not limited to these.

On the other hand, as the conductor, an inert material that is excellent in terms of overvoltage, polarity range, and chemical stability in electrochemical reduction may be used. In one embodiment, the conductor is glassy carbon and platinum (Pt), but is not limited thereto.

In order to coat the graphene oxide thin film on the conductor, a drying step is required at a predetermined temperature. Specifically, the predetermined temperature may be in the range of 50-80°C. Specifically, if the temperature for drying the conductor coated with the graphene oxide mixed solution is less than 50° C., it may take a long time to remove the solvent and form the graphene oxide thin film.

On the other hand, when the temperature for drying the conductor coated with the graphene oxide mixed solution exceeds 80° C., the polymer may be discolored or gradually decomposed. This is a problem caused by approaching or exceeding the glass transition temperature of the polymer. Specifically, the polymers in the graphene oxide mixed solution are heated, and deformation of the polymers may occur due to heat.

Next, in step S400, the conductor on which the graphene oxide thin film is formed is immersed in an electrolyte for electrochemical reduction, thereby forming a reduced graphene oxide thin film. Thus, reduced graphene oxide is produced.

In one embodiment, a three-electrode system comprising a reference electrode, a counter electrode and a working electrode may be formed to electrochemically reduce the graphene oxide thin film. That is, using the three-electrode system, reduced graphene oxide can be produced by reducing the graphene oxide thin film.

Specifically, the working electrode in which the reduction reaction is performed in the electrolyte in which the ionic substance is formed at a predetermined concentration may be composed of the conductor on which the graphene oxide thin film is formed. There is also a need for a counter electrode that mates with the working electrode to support oxidation or reduction of the working electrode. In addition, a reference electrode is required to set the reference potential.

In one embodiment, the ionic material of the electrolyte may be a material that dissociates into cations and anions, does not react with the graphene oxide, and transfers electrons so that the graphene oxide is reduced. The ionic substance may be lithium chloride (LiCl), sodium chloride (NaCl) and sodium nitrate (NaNO ₃ ).

Also, the conductor on which the graphene oxide thin film is formed may be immersed in an electrolyte at a temperature of 35 to 70° C. to be electrochemically reduced. When the temperature of the electrolyte is less than 35° C., the complete reduction of the graphene oxide takes several hours. Therefore, there is a problem that electrochemically reduced graphene oxide cannot be rapidly produced at room temperature. On the other hand, when the temperature of the electrolyte exceeds 70° C., the graphene oxide thin film is electrochemically reduced and the electrolyte may evaporate. Therefore, the preferred temperature of the electrolyte that can rapidly produce reduced graphene oxide by electrochemically reducing the graphene oxide is in the range of 35 to 70°C.

Also, the concentration of the electrolyte may range from 1M to a saturated solution. Reduction of graphene oxide with an electrolyte concentration below 1 M may result in a low charge capacity of the reduced graphene oxide. This is because when the concentration of the electrolyte is low, the diffusion layer at the interface of the working electrode becomes thick during the electrochemical reduction of the graphene oxide, and the graphene oxide is not smoothly reduced. In order to sufficiently reduce the graphene oxide and sufficiently activate the functional material therein, the concentration of the electrolyte is preferably 1 M or more.

The matters related to the electrolyte are merely examples, and the present invention is not limited thereto.

Furthermore, as a method for reducing the graphene oxide thin film, there are chronoamperometry (potentiostatic method) in which a voltage equal to or higher than the reduction voltage of graphene oxide is continuously applied, and cyclic voltammetry in which the voltage is continuously changed within a predetermined range. (circulating voltage current method). Graphene oxide reduced by these can be produced.

The reduced graphene oxide produced by reducing the graphene oxide thin film by chronoamperometry or cyclic voltammetry has voids. Accordingly, the active area per unit area is increased and the properties of the reduced graphene oxide are maximized.

Hereinafter, another embodiment will be described, but the same or similar reference numerals will be given to the same or similar configurations as those of the above embodiment, and the description thereof will be omitted.

As shown in FIG. 1B, the method for producing a reduced graphene oxide-functional material composite of the present invention comprises dispersing graphene oxide in a solvent to form a dispersion, and then dispersing the functional material and a predetermined solution. is supplied to form a mixed solution, the mixed solution is applied to a conductor, dried to form a thin film, and electrochemically reduced to form a reduced graphene oxide-functional substance Composites can be made.

First, in step S100', graphene oxide and a solvent are prepared. A dispersion is prepared by adding graphene oxide to the prepared solvent. A content of the graphene oxide in the dispersion may be 0.1 to 5% by weight.

In one embodiment, when the content of the graphene oxide is less than 0.1% by weight, it is difficult to form a graphene oxide thin film because the content of the graphene oxide is low as described above. In addition, uniform dispersion with the functional substance becomes difficult in the formation of a complex with the functional substance described later, self-aggregation of the functional substance occurs, and the aggregation causes the functional substance may not disperse uniformly in the solvent and may precipitate.

On the other hand, when the content of the graphene oxide exceeds 5% by weight, the graphene oxide solution has a very high viscosity and is very difficult to handle.

Next, in step S200', a functional material and a predetermined solution are supplied to the graphene oxide dispersion to form a graphene oxide-functional material mixture.

The functional materials supplied to the graphene oxide dispersion include silicon (Si) and titanium (Ti), which are electrochemically active particles that are added to the electrode of a secondary battery or a supercapacitor to cause a redox reaction on the surface of the electrode. ), vanadium (V), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), ruthenium (Ru), lead (Pb), antimony tin oxide (ATO) and these and one or more selected from the group consisting of oxides of

In addition, the functional substance includes nickel Prussian blue (Ni-PB), ferrocene, ferrocene derivatives, quinone, quinone derivatives, ruthenium amine complex, osmium (I), osmium (II), osmium (III) complexes, metallocenes and one or more of metallocene derivatives.

In one embodiment, nickel Prussian blue is an electrochemically active material capable of selectively separating cesium (Cs), a radioactive substance, as well as measuring the concentration of hydrogen peroxide (H ₂ O ₂ ). compound and Na battery electrode material. However, nickel Prussian blue has very small particles and is not easily processed in an aqueous solution.

Furthermore, the functional material is selected from iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), palladium (Pd) and platinum (Pt), which are used as active catalysts for the anode and cathode of fuel cells. may include one or more of the group

On the other hand, the predetermined solution supplied to the graphene oxide dispersion is a solution containing a polymer. Specifically, the polymer in the predetermined solution is a polymer capable of forming a coating film and having water solubility, and is mixed with the graphene oxide-functional substance composite to form a graphene oxide-functional substance composite. Helps form body membranes.

Then, in step S300', the graphene oxide-functional substance mixture is applied to a conductor and dried at a predetermined temperature to form a graphene oxide-functional substance composite thin film.

Next, in step S400′, the conductor on which the graphene oxide-functional substance composite thin film is formed is immersed in an electrolyte in a temperature range of 35 to 70° C. for electrochemical reduction. Graphene oxide-functional substance composite thin film is formed. Thus, a reduced graphene oxide-functional substance composite is produced.

FIG. 2A is a conceptual diagram showing the graphene oxide-functional substance composite 100 of the present invention.

FIG. 2A shows the graphene oxide-functional material composite 100 in step S300' described above. Specifically, the graphene oxide 10 , the activated functional material 20 a and the inactive functional material 20 b form the graphene oxide-functional material composite 100 on the conductor 1 .

Specifically, the activated functional material 20a and the inactive functional material 20b are uniformly distributed in the graphene oxide 10, but small voids are formed in the graphene oxide 10 layer. Therefore, the activated functional substance 20a is present on the surface of the composite thin film 100 to form an electrochemically activated region, whereas inside the composite thin film 100, Non-activated inactive functional material 20b is present to form an electrochemically non-activated region.

FIG. 2B is a conceptual diagram showing the reduced graphene oxide-functional substance composite 200 of the present invention.

FIG. 2B shows the reduced graphene oxide-functional material composite 200 of step S400' described above. Specifically, a reduced graphene oxide 10 ′ is formed on the conductor 1 by electrochemically reducing graphene oxide.

The reduced graphene oxide 10' prepared by chronoamperometry or cyclic voltammetry has many voids. Therefore, the functional material exists as an activated functional material 20 a instead of an inactive functional material even inside the reduced graphene oxide-functional material composite 200 . That is, an electrochemically activated region is formed over the entire region of the reduced graphene oxide-functional material composite 200 .

Therefore, the electrical conductivity of the reduced graphene oxide-functional material composite 200 is improved. In addition, the electrochemical reduction of graphene oxide increases the active area per unit area, and the activated functional material 20 a increases inside the reduced graphene oxide-functional material composite 200 . Therefore, the properties of the functional material in the reduced graphene oxide-functional material composite 200 are maximized.

Examples of the present invention will be described below.

A graphene oxide solution was formed by dispersing graphene oxide in distilled water and then supplying a 0.1 wt% polyvinyl alcohol aqueous solution. A uniform dispersion was prepared by irradiating the graphene oxide solution with ultrasonic waves for 10 minutes. 200ul of the uniformly dispersed graphene oxide solution was taken and applied to the glassy carbon. A graphene oxide thin film was manufactured by drying the glassy carbon coated with the graphene oxide mixture at a temperature of 60°C. A three-electrode system was formed by using glassy carbon with a graphene oxide thin film as the working electrode, platinum as the counter electrode, and Ag/AgCl as the reference electrode. The working electrode, the counter electrode and the reference electrode were immersed in an electrolyte solution of sodium nitrate (NaNO ₃ ) having a temperature of 25, 35, 50, 60 or 70° C. and a concentration of 5M. .2 to 1.2 V (vs. Ag/Ag+) by applying cyclic voltammetry or −1.2 V by applying chronoamperometry to electrochemically reduce the graphene oxide thin film. Graphene oxide thin films were fabricated.

FIG. 3 is a graph showing a cyclic voltammetry curve measured after reducing a graphene oxide thin film for a predetermined time.

As can be seen from FIG. 3, the measured current of the graphene oxide thin film increased as the constant potential application time increased. In the process, a reduced graphene oxide-functional material composite with a six-fold increase in charge capacity compared to the initial one was produced.

FIG. 4 is a graph showing the relationship between the specific capacity of graphene oxide thin films reduced at various temperatures and the reduction time.

As shown in (a) of FIG. 4, it takes at least 100 minutes or more to completely reduce the graphene oxide thin film at room temperature. As can be seen from FIG. 4B, which is an enlarged dotted line area in the graph of FIG. 4A, graphene oxide was reduced within several minutes at a high temperature of 35° C. or higher. In addition, when reduced at 60° C., the specific capacity of graphene oxide increased by about 30% compared to room temperature.

A graphene oxide-functional substance mixture was formed by dispersing graphene oxide in distilled water and then supplying nickel Prussian blue (Ni—PB) and 0.1 wt % polyvinyl alcohol aqueous solution. A uniform dispersion was prepared by irradiating the graphene oxide-functional substance mixture with ultrasonic waves for 10 minutes. 200 μl of the uniformly dispersed graphene oxide-functional substance mixture was taken and applied to glassy carbon. A graphene oxide-functional substance composite thin film was manufactured by drying the glassy carbon coated with the graphene oxide-functional substance mixture at a temperature of 60.degree.

A three-electrode system was formed by using the glassy carbon on which the graphene oxide-functional substance composite thin film was formed as the working electrode, platinum as the counter electrode, and Ag/AgCl as the reference electrode. Cyclic voltammetry in which the working electrode, counter electrode and reference electrode are immersed in an electrolyte solution of lithium chloride (LiCl) with a concentration of 14 M, and −1.2 to 1.2 V (vs. Ag/AgCl) is applied to the working electrode. and electrochemically reducing the graphene oxide-functional substance composite thin film containing nickel Prussian blue to produce a reduced graphene oxide-functional substance composite.

FIG. 5 is a graph of voltage and current measured during the reduction of the graphene oxide-functional material complex containing nickel Prussian blue by cyclic voltammetry.

As can be seen from FIG. 5, the measured current increased as the number of cycles for which cyclic voltammetry was performed increased. In the process, a reduced graphene oxide-functional material composite with a 50-fold increase in charge capacity compared to the initial one was produced.

A graphene oxide-functional substance mixture was formed by dispersing graphene oxide in distilled water and then supplying nickel Prussian blue (Ni—PB) and 0.1 wt % polyvinyl alcohol aqueous solution. A uniform dispersion was prepared by irradiating the graphene oxide-functional substance mixture with ultrasonic waves for 10 minutes. 200 μl of the uniformly dispersed graphene oxide-functional substance mixture was taken and applied to glassy carbon. A graphene oxide-functional substance composite thin film was manufactured by drying the glassy carbon coated with the graphene oxide-functional substance mixture at a temperature of 60.degree.

A three-electrode system was formed by using the glassy carbon on which the graphene oxide-functional substance composite thin film was formed as the working electrode, platinum as the counter electrode, and Ag/AgCl as the reference electrode. The working electrode, the counter electrode and the reference electrode were immersed in NaCl electrolytes with concentrations of 0.1 M, 1 M, 3 M and saturated concentrations (6.14 M) and LiCl electrolyte solutions with 1 M, 5 M and 10 M, and the working electrode was -1.2. By performing cyclic voltammetry applying ~1.2 V (vs. Ag/AgCl) and electrochemically reducing the graphene oxide-functional material composite thin film containing nickel Prussian blue, the reduced graphene oxide- A functional substance composite was produced.

FIG. 6 is a graph of measured voltage and current after reducing graphene oxide-functional material composites containing nickel Prussian blue with various concentrations of NaCl and LiCl electrolytes by cyclic voltammetry.

As can be seen from Figures 6(a) and (b), the measured current increased as the concentration of the electrolyte on which the cyclic voltammetry was performed increased. In the process, the charge capacity of the reduced graphene oxide-functional material composite increased by more than three times in the high-concentration electrolyte compared to the low-concentration electrolyte. This is because when the concentration of the electrolyte is low, the diffusion layer at the interface of the working electrode becomes thicker during the electrochemical reduction of graphene oxide, and the graphene oxide cannot be reduced smoothly. In order to reduce and sufficiently activate the functional substance therein, the concentration of the electrolyte is preferably 1M or more.

A graphene oxide-functional substance composite thin film was produced in the same manner as in Example 2. However, the functional substance was changed to silicon nanopowder.

A three-electrode system was formed by using the glassy carbon on which the graphene oxide-functional substance composite thin film was formed as the working electrode, platinum as the counter electrode, and Ag/AgCl as the reference electrode. The temperature is 60 ° C., the working electrode, the counter electrode and the reference electrode are immersed in an electrolyte solution of sodium chloride (NaCl) with a concentration of 3 M, and the working electrode is −1.2 to 1.0 V (vs. Ag/AgCl ) to electrochemically reduce the graphene oxide-functional substance composite thin film containing silicon nanopowder to produce a reduced graphene oxide-functional substance composite.

FIG. 7 is a graph of measured voltage and current after reducing the graphene oxide-functional material composite containing silicon nanopowder by cyclic voltammetry.

As can be seen from Figure 7, the measured current increased significantly after reduction of the complex. In the process, a reduced graphene oxide-functional material composite with increased charge capacity compared to the initial stage was produced.

Graphene oxide was dispersed in distilled water, then ruthenium chloride (RuCl ₃ ) was fed and titrated to pH 8. Ruthenium chloride (RuCl ₃ ) was converted to ruthenium oxide (RuO ₂ ) by titration. A mixture of graphene oxide and ruthenium oxide (RuO ₂ ) was supplied with a 0.1% by weight polyvinyl alcohol aqueous solution to form a graphene oxide-functional substance mixture. A uniform dispersion was prepared by irradiating the graphene oxide-functional substance mixture with ultrasonic waves for 10 minutes. 200 μl of the uniformly dispersed graphene oxide-functional substance mixture was taken and applied to glassy carbon. A graphene oxide-functional substance composite thin film was manufactured by drying the glassy carbon coated with the graphene oxide-functional substance mixture at a temperature of 60.degree.

A three-electrode system was formed by using the glassy carbon on which the graphene oxide-functional substance composite thin film was formed as the working electrode, platinum as the counter electrode, and Ag/AgCl as the reference electrode. The working electrode, the counter electrode and the reference electrode are immersed in an electrolyte solution of sodium chloride (NaCl) with a temperature of 60° C. and a concentration of 3 M, and −1.2 V (vs. Ag/AgCl) is applied to the working electrode. Chronoamperometry was performed for 600 seconds to electrochemically reduce the graphene oxide-functional substance composite thin film containing ruthenium oxide, thereby producing a reduced graphene oxide-functional substance composite.

FIG. 8 is a graph of measured voltage and current after reduction of a graphene oxide-functional material composite containing ruthenium oxide by chronoamperometry.

As can be seen from FIG. 8, the current increased in the graphene oxide-functional substance composite containing ruthenium oxide subjected to chronoamperometry for 600 seconds. In the process, a reduced graphene oxide-functional material composite with increased charge capacity compared to the initial graphene oxide without electrochemical reduction was produced.

A graphene oxide-functional substance composite thin film was produced in the same manner as in Example 2. However, the functional substance was changed to lead oxide (PbO ₂ ).

A three-electrode system was formed by using the glassy carbon on which the graphene oxide-functional substance composite thin film was formed as the working electrode, platinum as the counter electrode, and Ag/AgCl as the reference electrode. The temperature is 60 ° C., the working electrode, the counter electrode and the reference electrode are immersed in an electrolyte solution of sodium chloride (NaCl) with a concentration of 3 M, and the working electrode is −1.2 to 1.2 V (vs. Ag/AgCl ) to electrochemically reduce the graphene oxide-functional substance composite thin film containing lead oxide, thereby producing a reduced graphene oxide-functional substance composite.

FIG. 9 is a graph of measured voltage and current after reducing the graphene oxide-functional material composite containing lead oxide by cyclic voltammetry.

As can be seen from FIG. 9, the reduction of the graphene oxide-functional substance composite containing lead oxide increased the measured current. In the process, a reduced graphene oxide-functional material composite with increased charge capacity compared to the initial stage was produced.

A graphene oxide-functional substance composite thin film was produced in the same manner as in Example 2. However, the functional substance was changed to Antimony Tin Oxide (ATO).

A three-electrode system was formed by using the glassy carbon on which the graphene oxide-functional substance composite thin film was formed as the working electrode, platinum as the counter electrode, and Ag/AgCl as the reference electrode. The temperature is 60 ° C., the working electrode, the counter electrode and the reference electrode are immersed in an electrolyte solution of sodium chloride (NaCl) with a concentration of 3 M, and the working electrode is −1.2 to 0.9 V (vs. Ag/AgCl ) to electrochemically reduce the graphene oxide-functional substance composite thin film containing ATO to produce a reduced graphene oxide-functional substance composite.

FIG. 10 is a graph of voltage and current measured during reduction of a graphene oxide-functional material composite containing antimony tin oxide (ATO) by cyclic voltammetry.

As can be seen from Figure 10, reducing the complex increased the measured current. In the process, a reduced graphene oxide-functional material composite with increased charge capacity compared to the initial stage was produced.

Graphene oxide was dispersed in distilled water, then chloroplatinic acid (H ₂ PtCl ₆ ) was supplied and NaBH ₄ was added to reduce the platinic acid to platinum nanoparticles. A graphene oxide-functional substance mixed solution was formed by supplying a 0.1% by weight polyvinyl alcohol aqueous solution to a mixed solution of graphene oxide and platinum nanoparticles. A uniform dispersion was prepared by irradiating the graphene oxide-functional substance mixture with ultrasonic waves for 10 minutes. 200 ul of the uniformly dispersed graphene oxide-functional substance mixture is taken and applied to glassy carbon. A graphene oxide-functional substance composite thin film was manufactured by drying the glassy carbon coated with the graphene oxide-functional substance mixture at a temperature of 60.degree.

A three-electrode system was formed by using the glassy carbon on which the graphene oxide-functional substance composite thin film was formed as the working electrode, platinum as the counter electrode, and Ag/AgCl as the reference electrode. The working electrode, the counter electrode and the reference electrode are immersed in an electrolyte solution of sodium chloride (NaCl) with a temperature of 60° C. and a concentration of 3 M, and −1.2 V (vs. Ag/AgCl) is applied to the working electrode. Chronoamperometry was performed for 600 seconds to electrochemically reduce the graphene oxide-functional substance composite thin film containing platinum nanoparticles to produce a reduced graphene oxide-functional substance composite.

FIG. 11A is an electron microscope image measured after reducing the graphene oxide-functional substance composite containing platinum nanoparticles by chronoamperometry, and FIG. 11B is an energy dispersive X-ray analysis of the sample in FIG. These are the results of X-ray Spectroscopy, EDX).

As can be seen from FIGS. 11A and 11B, the graphene oxide-platinum particle production method and chronoamperometry were performed for 600 seconds, resulting in the production of a graphene oxide-functional material composite containing platinum nanoparticles.

The above-described method for producing reduced graphene oxide or reduced graphene oxide-functional substance composite is not limited to the configurations and methods of the above-described embodiments, and all or part of each embodiment can be selected. It can be modified in various ways by combining and configuring.

Claims (8)

dispersing graphene oxide in a solvent to form a graphene oxide dispersion;
supplying a functional material and a predetermined solution to the graphene oxide dispersion to form a graphene oxide-functional material mixture;
forming a graphene oxide-functional material composite thin film by coating the graphene oxide-functional material mixture on a conductor and drying it at a predetermined temperature;
The conductor on which the graphene oxide-functional substance composite thin film is formed is immersed in an electrolyte in a temperature range of 35 to 70° C. to electrochemically reduce the reduced graphene oxide-functional substance composite. forming;
The functional substance is electrochemically active compound nickel Prussian blue (Ni-PB), ferrocene, ferrocene derivative, quinone, quinone derivative, ruthenium amine complex, osmium (I), osmium (II), osmium (III). A method for producing a reduced graphene oxide-functional substance composite comprising at least one of a complex, a metallocene and a metallocene derivative. The graphene oxide dispersion is
a solvent;
2. The method for producing a reduced graphene oxide-functional material composite according to claim 1, comprising 0.1 to 5% by weight of the graphene oxide. 2. The method of claim 1, wherein the predetermined solution contains a water-soluble polymer. The water-soluble polymer includes polyvinylalcohol (PVA), polyacrylic acid (PAA), polyvinylpyrrolidone (PVP), polyethyleneglycol (PEG), and a sulfonic acid group on a polytetrafluoroethylene skeleton. 4. The method for producing a reduced graphene oxide-functional substance composite according to claim 3, comprising at least one polymer (Nafion) introduced with The predetermined solution is
a solvent;
4. The method for producing a reduced graphene oxide-functional material composite according to claim 3, comprising 0.05 to 0.2% by weight of the polymer. The reduced graphene oxide-functional material composite according to claim 1, wherein the predetermined temperature in the step of forming the graphene oxide-functional material composite thin film is in the range of 50 to 80 °C. body manufacturing method. The reduced graphene oxide-functionality of claim 1, wherein the concentration of the electrolyte in the step of forming the reduced graphene oxide-functional material complex is in the range of 1 M to a saturated solution. A method for manufacturing a substance complex. In the step of forming the reduced graphene oxide-functional substance composite, a three-electrode system including a reference electrode, a counter electrode and a working electrode is formed, and the graphene oxide-functional substance composite thin film is electrochemically 2. The method for producing the reduced graphene oxide-functional substance composite according to claim 1, wherein the reduction is performed to .

Images