KR101363297B1 - Electrodes for enzymatic fuel cells which a graphite oxide/cobalt hydroxide/chitosan-enzyme composite is electrodeposited on the electrode, methods for manufacturing the same, and enzymatic fuel cells comprising the same - Google Patents

Abstract

The present invention provides: an electrode for an enzymatic fuel cell which includes an electrode member, a graphite oxide/cobalt hydroxide/chitosan-enzyme composite deposited on the surface of the electrode member, and an enzyme for an oxidation reaction or an enzyme for a reduction reaction fixated on the surface of the graphite oxide/cobalt hydroxide/chitosan-enzyme composite; a manufacturing method of the same; and the enzymatic fuel cell comprising the same.

Description

Electrode for enzymatic fuel cell in which a graphite oxide / cobalt hydroxide / chitosan-enzyme composite is electrodeposited, a method for manufacturing the same, and an enzymatic fuel cell comprising the same on the electrode, methods for manufacturing the same, and enzymatic fuel cells comprising the same}

The present invention relates to an electrode for an enzyme fuel cell in which a graphite oxide / cobalt hydroxide / chitosan-enzyme composite is electrodeposited, a method for producing the same, and a method for producing an enzyme fuel cell including the same.

Enzymatic fuel cells have attracted much attention recently. Enzyme fuel cells use enzymes as catalysts and are manufactured using materials that are harmless to the human body so that they can operate under conditions such as room temperature, atmospheric pressure, and naturally occurring pH. ), Many applications in real life such as battery of small electronic products.

In such an enzyme fuel cell, it is important to increase the stability and activity of the enzyme and to create an optimized electron transfer environment. Therefore, various studies on the electron transporter are in progress.

However, enzyme fuel cells have problems such as short duration, low current density and low power density related to the stability of enzymes. Therefore, continuous research to solve these problems is required.

Republic of Korea Patent Publication No. 10-2012-0113085 Japanese Patent Laid-Open No. 2012-178335

The present invention has been made to solve the above-mentioned problems of the prior art, the electrode substrate is a graphite oxide / cobalt hydroxide / chitosan composite (graphite oxide / cobalt hydroxide / chitosan composite) that serves as an electron carrier and a fixed role of the enzyme The electrode for enzyme fuel cell having high uniformity and stability and improved enzyme activity, its preparation method and enzyme fuel comprising the same as electrode by uniform deposition on the surface of the polymer and immobilizing the enzyme for oxidation reaction or reduction reaction thereon It is an object to provide a battery.

According to the present invention,

Electrode substrates;

Graphite oxide / cobalt hydroxide / chitosan composites deposited on the surface of the electrode substrate; And

An electrode for an enzymatic fuel cell (EFC) comprising an enzyme for oxidation reaction or an enzyme for reduction reaction immobilized on a surface of the graphite oxide / cobalt hydroxide / chitosan composite is provided.

The present invention also relates to

(a) depositing a graphite oxide / cobalt hydroxide / chitosan composite on the electrode substrate; And

(b) providing a method for manufacturing an electrode for an enzymatic fuel cell (EFC) comprising the step of immobilizing an enzyme for oxidation reaction or an enzyme for reduction reaction on the surface of a graphite oxide / cobalt hydroxide / chitosan composite deposited on an electrode substrate.

The present invention also relates to

It provides an enzyme fuel cell, characterized in that comprising an electrode for the enzyme fuel cell (EFC).

The electrode for an enzyme fuel cell of the present invention uniformly deposits a graphite oxide / cobalt hydroxide / chitosan composite (graphite oxide / cobalt hydroxide / chitosan composite) which serves as an electron carrier and a fixing enzyme, By immobilizing the enzyme for the oxidation reaction or the enzyme for the reduction reaction in the above, there is provided an electrode for an enzyme fuel cell with high uniformity and stability and improved enzyme activity.

In addition, the enzyme fuel cell of the present invention comprising the electrode for the enzyme fuel cell provides a high power density and current density.

1 is a diagram schematically illustrating a manufacturing process of a graphite oxide / cobalt hydroxide composite,
FIG. 2 schematically illustrates a process of depositing a graphite oxide / cobalt hydroxide / chitosan composite on an electrode substrate,
FIG. 3 schematically illustrates a process of immobilizing an enzyme for oxidation reaction or an enzyme for reduction reaction on the surface of graphite oxide / cobalt hydroxide / chitosan composite deposited on the surface of an electrode substrate,
Figure 4 is a graph showing the results of measuring the pattern of graphite oxide / cobalt hydroxide composites using an X-ray photoelectron spectroscope (XPS) ((a): the pattern of graphite oxide, (b): graphite oxide / Pattern of cobalt hydroxide composites],
Figure 5 is a graph showing the analysis of the surface of the graphite oxide / cobalt hydroxide composite by Fourier Transform Infrared Spectroscopy (FT-IR) ((a): graphite oxide, (b): graphite oxide / cobalt hydroxide),
FIG. 6 is an image showing a graphite oxide / cobalt hydroxide composite by TEM (transmission electron microscopy). [(A): Graphite oxide, (b) graphite oxide / cobalt hydroxide composite]
In Figure 7 (a) is a scanning electron microscopy (SEM) image of the surface of the Au electrode, and (b) is a SEM photographed electrode on which the graphite oxide / cobalt hydroxide / chitosan composite is deposited on the surface of the Au electrode (C) is an SEM image of an electrode coated with a graphite oxide / cobalt hydroxide / chitosan compound on the surface of Au and having glucose oxidase immobilized thereon as an oxidase.
8 is a graph showing Raman by Raman spectroscopy [(a): Graphite oxide / cobalt hydroxide / chitosan compound, (B) graphite oxide / cobalt hydroxide / chitosan-enzyme compound],
9 shows an Au electrode, an electrode on which a graphite oxide / chitosan composite is deposited on an Au surface, an electrode on which a graphite oxide / cobalt hydroxide / chitosan composite is deposited on an Au surface, and a graphite oxide / cobalt hydroxide / chitosan-enzyme composite on an Au surface It is a graph comparing the circulating voltage current of the deposited electrode,
10 is a graph showing the results of measuring the voltage of the electrode on which the graphite oxide / cobalt hydroxide / chitosan-enzyme composite prepared in Example 3 is deposited;
FIG. 11 is a graph illustrating measurement of current density and power density of the enzyme fuel cell manufactured in Example 4. FIG.

According to the present invention,

Electrode substrates;

Graphite oxide / cobalt hydroxide / chitosan composites deposited on the surface of the electrode substrate; And

The present invention relates to an electrode for an enzymatic fuel cell (EFC) comprising an enzyme for oxidation reaction or an enzyme for reduction reaction immobilized on a surface of the graphite oxide / cobalt hydroxide / chitosan composite.

As the electrode substrate, various metal materials and carbon materials such as gold, silver, platinum, copper, aluminum, carbon nanotubes, and graphene may be used.

Graphene is widely used as a carbon material for the conversion / storage system of electrical energy because of its high surface area, chemical stability, electrical conductivity, and thermal conductivity. Among them, graphite oxide used in the present invention has various surface properties and layer structure derived from graphene. In particular, it has a large surface area, and can be used as a nucleus of an active material such as a metal hydroxide by various substituents formed in the carbon nanolayer, and thus it is widely used as a support.

 Cobalt hydroxide is an electrochemical redox active material, and because of its large layered structure, it is widely used as a material for alkaline batteries, fuel cells, secondary batteries, and supercapacitors.

The graphite oxide / cobalt hydroxide composite used in the present invention is combined with graphite oxide and cobalt hydroxide to provide an effect of increasing the electrochemical properties.

In addition, when chitosan is applied to the graphite oxide / cobalt hydroxide composite, the electrode is electro-deposited to the electrode substrate, and the enzyme is immobilized thereon to be used as an electrode for an enzyme fuel cell, so that the stability and activity of the enzyme are increased. Improve the density and current density.

The present invention also relates to

(a) depositing a graphite oxide / cobalt hydroxide / chitosan composite on the electrode substrate; And

(b) a method of manufacturing an electrode for an enzymatic fuel cell (EFC) comprising the step of immobilizing an enzyme for oxidation reaction or an enzyme for reduction reaction on the surface of a graphite oxide / cobalt hydroxide / chitosan composite deposited on an electrode substrate.

In the step (a), the deposition of the graphite oxide / cobalt hydroxide / chitosan composite is performed by dipping the electrode substrate in a solution in which the graphite oxide / cobalt hydroxide / chitosan composite is dissolved and causing the electrode substrate to have a negative charge. It can be carried out by applying a process to deposit a graphite oxide / cobalt hydroxide / chitosan composite on the surface of the electrode substrate.

In the step (a), the immobilization of the oxidizing enzyme or the reducing enzyme may be performed using, for example, a crosslinking compound of the oxidizing enzyme or the reducing enzyme and the graphite oxide / cobalt hydroxide / chitosan composite.

Examples of the crosslinking compound include EDC and NHS.

In more detail, a solution is prepared by mixing an enzyme for oxidation reaction or an enzyme for reduction reaction with EDC and NHS as a crosslinking compound, and immersing an electrode substrate having the graphite oxide / cobalt hydroxide / chitosan compound deposited on the surface thereof. The oxidation enzyme or the reduction enzyme may be carried out in such a manner as to immobilize EDC and NHS on the surface of the graphite oxide / cobalt hydroxide / chitosan composite.

In the above, EDC and NHS are covalently bonded to the oxidizing enzyme or the reducing enzyme and the graphite oxide / cobalt hydroxide / chitosan composite.

The method of immobilizing the oxidation enzyme or the reduction enzyme on the surface of the graphite oxide / cobalt hydroxide / chitosan composite may be used without limitation by methods known in the art in addition to the method by the covalent bond.

The solution in which the graphite oxide / cobalt hydroxide / chitosan composite is dissolved in step (a) may be prepared by mixing and reacting the graphite oxide / cobalt hydroxide composite to the chitosan solution.

By the above method, chitosan is uniformly fixed on the surface of the graphite oxide / cobalt hydroxide composite and has high stability.

The chitosan solution can be prepared using acetic acid as a solvent.

The graphite oxide / cobalt hydroxide composite, which serves as a mediator, is reacted by adding CoCl ₂ H ₂ O to a solution in which graphite oxide is dispersed, _and then adding NH ₄ OH to the reaction solution. Can be prepared.

In the step (a), various metal materials and carbon materials, such as gold, silver, platinum, copper, aluminum, carbon nanotubes, and graphene, may be used as the electrode substrate.

As the enzyme for oxidation reaction and the enzyme for reduction reaction in step (b), those known in the art may be used. For example, when glucose is used as a substrate, enzymes for oxidation reaction include glucose oxidase, glucose dehydrogenase, cellobiose dehydrogenase, and dehydrogenase. And the like, and a reduction enzyme may include laccase, horseradish peroxidase, bilirubin oxidase, and the like.

The present invention also relates to an enzyme fuel cell comprising the electrode for enzyme fuel cell (EFC).

In the enzyme fuel cell, other components except for the electrode for the enzyme fuel cell (EFC) can be used without limitation those conventionally used in this field, combining them by a conventional method the enzyme fuel cell of the present invention Can be prepared.

Enzyme fuel cell of the present invention by using the graphite oxide / cobalt hydroxide / chitosan compound to fix the enzyme for the oxidation reaction or the reduction reaction can provide a high power density and current density.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples are provided to illustrate the present invention, and the present invention is not limited to the following examples and may be variously modified and changed. The scope of the invention will be defined by the technical spirit of the claims below.

Example  One: Oxidized graphite / Cobalt Hydroxide Composite Synthesis

The best known Brodie method was used to oxidize graphite. 4 g graphite, NaClO ₃ After mixing in 34g HNO ₃ 100 ml was added and stirred for 24 hours. Then, 2000 ml of tertiary distilled water was added for washing, followed by stirring, and the graphite oxide was dried at 110 ° C. using a centrifuge.

As shown in Figure 1, 0.1g of graphite oxide (graphite oxide) was added to 10ml of tertiary distilled water to synthesize a graphite oxide / cobalt hydroxide composite at room temperature and dispersed for 1 hour. CoCl ₂ H ₂ O (2M) was then dissolved in 10 ml of tertiary distilled water. The two solutions were mixed and allowed to adsorb cobalt ions onto the graphite oxide with stirring for 24 hours. After 24 hours, NH ₄ OH was added to pH 9.0, followed by stirring for 24 hours, so that the cobalt ions adsorbed on the graphite oxide became cobalt hydroxide. The graphite oxide / cobalt hydroxide composite thus formed was washed with tertiary distilled water and then dried in a 60 ° C. vacuum oven for 2 hours.

Example  2: Au  For electrodes Oxidized graphite / Cobalt Hydroxide / Chitosan Composite Deposition

0.1 g of chitosan was dissolved in a solution containing 100 ml of 25 × TAE (Tris-acetate-EDTA) buffer and 3% acetic acid and filtered through a nylon filter. Then, as shown in FIG. 2, 3 g of the graphite oxide / cobalt hydroxide compound and 0.1 wt% of the chitosan solution (relative to the total weight of the mixture) were mixed so that the chitosan solution was coated on the graphite oxide / cobalt hydroxide compound. In the mixed solution, as shown in FIG. 2, the Au anode and the Au cathode of the power supply were immersed and 50V was applied to deposit a graphite oxide / cobalt hydroxide / chitosan compound on the Au electrode for 2 minutes. Graphite oxide / cobalt hydroxide / chitosan compounds are deposited on the Au cathode, which is electrically negative, because dissolved chitosan carries a positive charge.

Example  3: electronic delivery chain Oxidized graphite Immobilization of Oxidation or Reduction Enzymes on Cobalt Hydroxide / chitosan Composites

In order to prepare an anode or a cathode to which an enzyme for oxidation or reduction reaction is immobilized as shown in FIG. 3, glucose oxidation, an enzyme for oxidation reaction, in 0.1M phosphate buffer (pH 7.0) 0.1 mg / ml, 0.5mg / ml, 1mg / ml, 2mg / ml, 3mg / ml and 4mg / ml, respectively, were mixed with glucose oxidase or reduction enzyme laccase, and 0.12M EDC After mixing 0.14M NHS together, the Au electrode on which the graphite oxide / cobalt hydroxide / chitosan composite was deposited was immersed at 4 ° C. for 8 hours. At this time, the enzyme is immobilized on the graphite oxide / cobalt hydroxide / chitosan compound by the EDC / NHS reaction. This reaction takes place by the covalent linkage of the carboxyl group in the enzyme with the amine group of chitosan. After the immobilization proceeded, it was washed with 0.1M phosphate buffer and tertiary distilled water.

Example  4: using an electrode to which an enzyme for oxidation reaction is immobilized and an electrode to which an enzyme for reduction reaction is immobilized Enzymatic  Construction of Fuel Cell, Voltage (V) -Current (I) and Power Density ( Power density )

As shown in Figure 3, using the electrode on which the glucose oxidase immobilized on the graphite oxide / cobalt hydroxide / chitosan composite prepared in Example 3 as an anode, the graphite oxide / cobalt hydroxide / chitosan composite phase Electrodes with immobilized ERase reductase were connected to each other using a cathode, and an electrolyte containing 0.1 M glucose in a 0.05 M phosphate buffer (pH 7.0) serving as a fuel was used. A basic enzyme fuel cell without ion membrane was produced.

The enzyme fuel cell was connected to potentiostat / galvanostat (WPG100, WonATech, Korea) and WPG program (WPG100, WonATech, Korea) at 25 ° C for voltage (V) -current (I) and power density. Was measured.

As a result of the experiment, when using the graphite oxide / cobalt hydroxide / chitosan composite, it was confirmed that an output density of up to 517 μW / cm ² (1114.65 μA / cm 2, 0.46V) is obtained.

Test Example  One: XPS  Pattern measurement

The pattern of the graphite oxide / cobalt hydroxide composite of Example 1 was measured using an X-ray photoelectron spectroscope (XPS) and is shown in FIG. 4.

Figure 4 (a) shows a pattern of graphite oxide (graphite), the binding energy of the XPS range was confirmed that only C1s and O1s are displayed, no other metal-based inorganic material.

Figure 4 (b) shows a pattern of graphite oxide / cobalt hydroxide composite, it was confirmed that only the binding energy in the XPS range of 780.9 eV and 796.5 eV Co2P.

Through the test it was found that the graphite oxide / cobalt hydroxide composites are present.

Test Example  2: FT - IR  Surface measurement

The surface of the graphite oxide / cobalt hydroxide composite of Example 1 was shown in FIG. 5 by analyzing Fourier Transform Infrared Spectroscopy (FT-IR).

It can be seen from the results of FIG. 5 that the wavenumbers shown in (a) graphite oxide and (b) graphite oxide / cobalt hydroxide are different. Through this, it was found that cobalt hydroxide was adsorbed on the graphite oxide surface.

Test Example  3: TEM  Image measurement

The graphite oxide / cobalt hydroxide composite of Example 1 was photographed by transmission electron microscopy (TEM) and shown in FIG. 6.

As shown in FIG. 6, (a) graphite oxide and (b) graphite oxide / cobalt hydroxide composites are different images, and (b) graphite oxide / cobalt hydroxide composites have rod-shaped particles (cobalt hydroxide) on graphite oxide. It was confirmed that it was adsorbed.

Test Example  4: SEM  Image measurement

A surface of an Au electrode, an electrode on which a graphite oxide / cobalt hydroxide / chitosan composite was deposited on the surface of the Au electrode (Example 2), and a graphite oxide / cobalt hydroxide / chitosan composite on the surface of Au were deposited thereon as an oxidase. The electrode (Example 3) to which glucose oxidase was immobilized was photographed by scanning electron microscopy (SEM) and shown in FIG. 7.

Fig. 7A shows the Au electrode surface. The Au electrode surface was slightly rough but generally smooth and flat.

FIG. 7B illustrates an electrode on which a graphite oxide / cobalt hydroxide / chitosan compound is deposited on the surface of the Au electrode. It can be seen that the graphite oxide / cobalt hydroxide / chitosan composite is deposited on the surface of the Au electrode by the electro deposition method, thereby forming a large surface area and a bumpy surface.

FIG. 7C shows an electrode coated with a graphite oxide / cobalt hydroxide / chitosan compound on the surface of Au and having glucose oxidase immobilized thereon as an oxidase. By fixing the oxidase from the image (c) of FIG. 7, it was confirmed that the empty space on the rugged surface of FIG. 7 (b) was reduced.

Test Example  5: Raman  Measure

Raman was measured by Raman spectroscopy to compare the electrodeposition of the graphite oxide / cobalt hydroxide / chitosan composite (Example 2) and the graphite oxide / cobalt hydroxide / chitosan-enzyme composite (Example 3) and the immobilization of the enzyme. Shown in

Figure 8 (a) shows the results of measuring the graphite oxide / cobalt hydroxide / chitosan composite. Here, the Raman band 1354.5-1601.6 cm ^-1 of graphite oxide and the Raman band 520cm ^-1 of cobalt hydroxide were measured together.

Figure 8 (b) shows the result of measuring the graphite oxide / cobalt hydroxide / chitosan-enzyme complex. The Raman band was measured only at 1347.8 ~ 1581.6 cm ^-1 .

From the above results, it was confirmed that the enzymes were immobilized on the surface of the graphite oxide / cobalt hydroxide / chitosan composite through the evaporation.

Test Example  6: cyclic current voltage CV cycle ) Measure

9 shows an Au electrode, an electrode on which a graphite oxide / chitosan composite is deposited on an Au surface, an electrode on which a graphite oxide / cobalt hydroxide / chitosan composite is deposited on an Au surface, and a graphite oxide / cobalt hydroxide / chitosan-enzyme composite on an Au surface In the case of deposited electrodes, it is a graph comparing the effect of these on the cyclic voltammogram values.

As confirmed from FIG. 9, the graphite oxide / cobalt hydroxide / chitosan-enzyme electrode was found to have a redox area larger than that of other electrodes, and the electron transport ability was also superior to other electrodes. .

Test Example  7: Voltage of cathode or anode according to the concentration of immobilized enzyme ( voltage ) Measure

The voltage was measured with respect to the electrode produced in Example 3, and the result is shown in FIG.

As shown in FIG. 10, it was confirmed that the maximum voltage was increased to 0.61 V when the concentration of glucose oxidase was 1 mg / ml, and the maximum voltage was increased to 0.59 V when the concentration of laccase was 0.5 mg / ml. It was confirmed.

Test Example  8: Current Density of Enzyme Fuel Cell Using Electrode (cathode and Anode) of the Invention current density ) And power density ( power density ) Measure

When the negative electrode and the positive electrode were used together as in Example 4, the current density and power density of the enzyme fuel cell were measured and shown in FIG. 11.

When using the graphite oxide / cobalt hydroxide / chitosan composite from Figure 11, it was confirmed that the output density of up to 517 μW / cm ² (1114.65 μA / cm 2, 0.46V) is produced.

Claims (10)

An electrode substrate;
Graphite oxide / cobalt hydroxide / chitosan composites deposited on the surface of the electrode substrate; And
An electrode for an enzymatic fuel cell (EFC) comprising an enzyme for oxidation reaction or an enzyme for reduction reaction immobilized on the surface of the graphite oxide / cobalt hydroxide / chitosan composite. The method according to claim 1,
The electrode substrate is an electrode for enzyme fuel cell (EFC), characterized in that selected from the group consisting of gold, silver, platinum, copper, aluminum, carbon nanotubes and graphene. (a) depositing a graphite oxide / cobalt hydroxide / chitosan composite on the electrode substrate; And
(B) a method for producing an electrode for an enzyme fuel cell (EFC) comprising the step of immobilizing the oxidation reaction enzyme or the reduction reaction enzyme on the surface of the graphite oxide / cobalt hydroxide / chitosan composite deposited on the electrode substrate. The method according to claim 3,
In the step (a), the deposition of the graphite oxide / cobalt hydroxide / chitosan composite is performed by dipping the electrode substrate in a solution in which the graphite oxide / cobalt hydroxide / chitosan composite is dissolved, and applying electricity so that the electrode substrate has a negative charge. Method for producing an electrode for enzyme fuel cell (EFC), characterized in that the graphite oxide / cobalt hydroxide / chitosan composite is deposited on the surface of the electrode substrate. The method according to claim 3,
In the step (a), the immobilization of the oxidizing enzyme or the reducing enzyme is carried out using an enzyme or a reducing enzyme and a crosslinking compound of a graphite oxide / cobalt hydroxide / chitosan compound. Method of manufacturing an electrode for a battery (EFC). The method according to claim 5,
The crosslinking compound is a method for producing an electrode for enzyme fuel cell (EFC), characterized in that EDC and NHS. The method of claim 4,
The solution in which the graphite oxide / cobalt hydroxide / chitosan composite is dissolved is prepared by mixing and reacting the graphite oxide / cobalt hydroxide composite in a chitosan solution. The method of claim 7,
The chitosan solution is a method for producing an electrode for enzyme fuel cell (EFC), characterized in that it contains acetic acid (acetic acid) as a solvent. The method of claim 7,
The graphite oxide / cobalt hydroxide composite is prepared by reacting CoCl _{2 ·} H ₂ O with a graphite oxide dispersion, _and then adding NH ₄ OH to the reaction solution to react the enzyme fuel cell (EFC). Method for producing an electrode for use. Enzyme fuel cell comprising an electrode for enzyme fuel cell (EFC) of claim 1.

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