JP2008019120A - Electrode material, its production method, electrochemical sensor, electrode for fuel cell, oxygen reduction catalyst electrode and biosensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode material in which the amount of the catalyst metal such as platinum to be used can be reduced, to provide its production method, to provide an electrochemical sensor, to provide an electrode for a fuel cell, to provide an oxygen reduction catalyst electrode, and to provide a biosensor. <P>SOLUTION: Using glassy carbon as a working electrode 12, a platinum wire as a counter electrode 14, and a silver-silver chloride electrode as a standard electrode 16, an ammonium carbamate aqueous solution of 0.1M is subjected to electrolytic oxidation at a fixed potential from 0.8 to 1.3V for 1hr. In this way, an electrode material in which an amino group is covalent-bonded to the surface of the glassy carbon is obtained. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrode material, a method for producing the same, an electrochemical sensor, a fuel cell electrode, an oxygen reduction catalyst electrode, and a biosensor.

  Conventionally, conductive carbon materials having a graphite structure have been widely used as battery electrodes, electrochemical sensor electrodes, and the like. However, the oxidation-reduction characteristics are not always satisfactory, and techniques such as catalyst loading have been developed in order to perform electrolytic oxidation-reduction as quickly as possible.

For example, Patent Document 1 below discloses a fuel cell electrode in which metal fine particles such as platinum are dispersedly supported on the pore surface walls of a porous carbon film.
JP 2004-335459 A

  However, in the above conventional technique, since expensive platinum is used as a catalyst, there is a problem that the cost is increased. Therefore, the above problem can be solved if the amount of the expensive catalytic metal such as platinum is reduced or the oxidation-reduction characteristics of the electrode can be maintained and improved without use.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide an electrode material capable of reducing the amount of catalyst metal such as platinum, a manufacturing method thereof, an electrochemical sensor, a fuel cell electrode, oxygen It is to provide a reduction catalyst electrode and a biosensor.

  In order to achieve the above object, the present invention is an electrode material, wherein a nitrogen-containing functional group is covalently bonded to the surface of a carbon material.

  In the electrode material, the nitrogen-containing functional group is preferably an amino group.

  In the above electrode material, the carbon material is preferably a carbon material having conductivity, and in particular, any one of glassy carbon, carbon nanotube, carbon felt, plastic molded carbon, or diamond electrode is preferable. It is.

  The present invention is also a method for producing an electrode material, characterized in that an aqueous solution containing carbamic acid is electrolytically oxidized using a carbon electrode, and a nitrogen-containing functional group is covalently bonded to the surface of the carbon electrode.

  In the method for producing the electrode material, the nitrogen-containing functional group is preferably an amino group.

  In the method for producing an electrode material, the aqueous solution containing carbamic acid is preferably ammonium carbamate, ammonium carbonate, or ammonium hydrogen carbonate.

  In addition, the present invention is an electrochemical sensor using the electrode material manufactured by the electrode material or the method for manufacturing the electrode material.

  In addition, the present invention is an electrode for a fuel cell, wherein the electrode material manufactured by the electrode material or the method for manufacturing the electrode material is used.

  In addition, the present invention is an oxygen reduction catalyst electrode, characterized in that the electrode material manufactured by the electrode material or the electrode material manufacturing method is used.

  In the oxygen reduction catalyst electrode, it is preferable that the noble metal catalyst is platinum.

  In addition, the present invention is a biosensor using the electrode material or the electrode material manufactured by the method for manufacturing the electrode material.

  In the biosensor, the molecular recognition agent is preferably an enzyme, a biocatalyst, an antigen, or an antibody.

  According to the present invention, since the nitrogen-containing functional group is covalently bonded to the carbon atom on the surface of the carbon material, the redox characteristics of the electrode can be improved.

  Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings.

  The present invention is characterized in that the electrode material has improved redox characteristics by covalently bonding a nitrogen-containing functional group to a carbon atom on the surface of the carbon material.

  As an embodiment of the electrode material according to the present invention, the nitrogen-containing functional group is preferably an amino group. Further, this amino group may be oxidized to form a nitro group or a nitroso group. Moreover, the carbon material of this embodiment has conductivity required as an electrode material, and graphite or the like is preferable. For example, glassy carbon, carbon nanotube, carbon felt, plastic molded carbon, diamond electrode, or the like can be used.

  In order to covalently bond the amino group to the carbon atom on the surface of the carbon material, the carbamic acid is directly covalently bonded to the carbon atom on the surface of the carbon material by electrolytic oxidation of an aqueous solution containing carbamic acid using the carbon material as an electrode. A method in which an amino group is directly introduced into a carbon atom on the surface of a carbon material by a covalent bond by decarboxylation is preferable. As the aqueous solution containing the carbamic acid, ammonium carbamate, ammonium carbonate, or ammonium bicarbonate can be suitably used.

An example in which the amino group is directly covalently bonded to the carbon atom on the surface of the carbon material as described above is shown below.

  As shown in the above structural formula, in addition to amino groups, oxygen-containing functional groups such as hydroxyl groups and carboxylic acids are bonded to the surface of the carbon material. For this reason, electrode characteristics such as redox characteristics can be improved by the interaction between the oxygen-containing functional group group and the nitrogen-containing functional group group coexisting on the surface of the carbon material. For this reason, even if it reduces the usage-amount of catalyst metals, such as platinum, the electrolytic oxidation reduction capability of an electrode can be maintained.

  On the other hand, an amino group introduced by reacting a hydroxyl group on the surface of the carbon material with an organosilicon compound having an amino group such as chlorosilane or alkoxysilane, that is, at the end of a molecular chain bonded to the surface of the carbon material. When the amino group is introduced in a pendant state, the interaction with the oxygen-containing functional group is low, and electrode characteristics such as redox characteristics cannot be sufficiently improved.

  In addition, since the electrode material according to the present embodiment has improved electrode characteristics such as oxidation-reduction characteristics as described above, it may be used for electrochemical sensors, fuel cell electrodes, oxygen reduction catalyst electrodes, biosensors, and the like. Is preferred. The biosensor is configured by chemically immobilizing a molecular recognition agent such as an enzyme, a biocatalyst, an antigen or an antibody on a nitrogen-containing functional group such as an amino group covalently bonded to the surface of the electrode material.

  Hereinafter, specific examples of the present invention will be described as examples. This example is an example of the present invention, and the present invention is not limited to this example.

Example 1.
The nitrogen-containing functional group was covalently bonded to the carbon atom on the surface of the carbon material by the following procedure.

  Glassy carbon was selected as the carbon material, and 0.1 M (mol / liter) aqueous ammonium carbamate solution was electrolytically oxidized using this as the working electrode.

  FIG. 1 shows a configuration example of the electrolytic oxidation apparatus for the ammonium carbamate aqueous solution. In FIG. 1, a 0.1M ammonium carbamate aqueous solution is placed as an electrolyte in a plastic container 10 having a diameter of 2.5 cm and a depth of 5 cm, a glassy carbon electrode having a diameter of 3 mm (manufactured by BIAS Co., Ltd.) as a working electrode 12, and a counter electrode 14 being 0 Constant potential electrolytic oxidation was performed by a three-electrode method using a 5 mm platinum wire and a silver-silver chloride electrode (Ag / AgCl) as the reference electrode 16. The working electrode 12 was used after being polished with submicron alumina particles. For the ammonium carbamate, a special grade manufactured by Merck & Co. was used. The constant potential electrolysis is performed by applying a constant potential (between 0.8V and 1.3V) to the reference electrode 16 to the working electrode 12 using a voltametric analyzer (HZ3000 manufactured by Hokuto Denko) as the potentiostat 18. Went for hours. In addition, the ammonium carbamate aqueous solution was stirred with the stirrer 20 during constant potential electrolysis. After the electrolytic oxidation treatment, the working electrode 12 was washed with distilled water to produce a carbon electrode to which an amino group that is a nitrogen-containing functional group was bonded.

  FIG. 2 shows a change with time of the electrolytic oxidation current when electrolytic oxidation of the ammonium carbamate aqueous solution is performed. In FIG. 2, it can be seen that the electrolytic oxidation current of carbamic acid increases with the passage of electrolysis time. This is because carbamic acid is electrochemically modified on the surface of the glassy carbon electrode, and the oxidation catalytic activity of the electrode gradually increases.

  3A and 3B show the results of measuring the surface of the glassy carbon electrode by X-ray photoelectron spectrophotometry (XPS). 3A shows a glassy carbon electrode that has not been subjected to electrolytic oxidation treatment of an aqueous ammonium carbamate solution, and FIG. 3B shows a glassy carbon electrode that has undergone electrolytic oxidation treatment. In FIGS. 3A and 3B, the energy of electrons detected on the horizontal axis is shown as binding energy for the nucleus, and the number of detected electrons is shown on the vertical axis.

  In FIG. 3B in which the electrolytic oxidation treatment was performed, a peak of N1s not observed in FIG. 3A in which the electrolytic oxidation treatment was not performed is observed, but this peak represents a covalent bond between carbon and nitrogen. Show. This shows that nitrogen atoms were directly introduced into the surface of the glassy carbon electrode by electrolytic oxidation of carbamic acid.

  FIG. 4 shows a mechanism in which nitrogen atoms of carbamic acid are introduced to the surface of the glassy carbon electrode by covalent bonds. In FIG. 4, the one-electron radical of carbamic acid is covalently bonded to the carbon atom on the surface of the glassy carbon electrode, and the carboxylic acid is desorbed as carbon dioxide. As a result, amino groups are introduced on the surface of the glassy carbon electrode.

  The introduction of an amino group on the surface of the glassy carbon electrode was confirmed by performing cyclic voltammetry of catechol. That is, it is known that catechol is electrochemically oxidized to 1,2-benzoquinone, but this substance binds to an amino group and exhibits a redox wave at a potential different from that of catechol (Document Electroanalysis, 10: 647, 1998). Therefore, cyclic voltammetry of catechol was performed with the glassy carbon electrode subjected to the electrolytic oxidation treatment.

  5 (a) and 5 (b) show the results of catechol cyclic voltammetry performed with the glassy carbon electrode. FIG. 5 (a) is a cyclic voltammogram of a phosphate buffer obtained using a glassy carbon electrode subjected to electrolytic oxidation treatment, and FIG. 5 (b) is a glassy carbon used in FIG. 5 (a). It is a cyclic voltammogram of the phosphate buffer obtained by using an electrode after washing | cleaning an electrode with a pure water. 5A and 5B, the horizontal axis represents the potential with respect to the Ag / AgCl reference electrode, and the vertical axis represents the current.

  In FIG. 5A, redox waves different from catechol redox waves (Ia and Ic) were observed (IIa and IIc). This is a redox wave of a substance in which 1,2-benzoquinone produced by electrochemical oxidation of catechol and an amino group present on the surface of a glassy carbon electrode are combined. The oxidation-reduction wave is further clarified by a cyclic voltammogram obtained after washing the glassy carbon electrode with pure water (IIa and IIc in FIG. 5B). From this result, it was confirmed that amino groups were introduced on the surface of the glassy carbon electrode by electrolytic oxidation of carbamic acid.

Example 2
In the same manner as in Example 1, cyclic voltammetry was performed on a glassy carbon electrode in which an amino group was covalently bonded to a carbon atom on the surface, and the reduction potential of oxygen was measured. As a comparative example, the same measurement was performed on a glassy carbon electrode in which an amino group was not covalently bonded to a surface carbon atom.

  In the cyclic voltammetry, a glassy carbon electrode having an amino group introduced on its surface, a platinum wire counter electrode, and a silver-silver chloride reference electrode are placed in a 0.1 M phosphate buffer solution (pH 7) containing a substance to be electrolyzed. It was carried out in a potential range of 0.0 V to +1.0 V. The potential sweep rate was 100 mV / sec, and the measurement was performed at room temperature. The same electrolytic cell as that shown in FIG. 1 was used.

  FIG. 6 shows the measurement result of the reduction potential. In FIG. 6, curve A is a measurement result at a glassy carbon electrode that has not been subjected to electrolytic oxidation treatment of carbamic acid, and curve B is a measurement result at a glassy carbon electrode that has been subjected to electrolytic oxidation treatment of carbamic acid, Curve C is a measurement result with a glassy carbon electrode carrying platinum after electrolytic oxidation treatment of carbamic acid.

When the carbamic acid electrolytic oxidation treatment is not performed, the oxygen reduction wave Ic rises in the vicinity of about −0.4 V (vs. Ag / AgCl) as shown by the curve A in FIG. In the case of the electrolytic oxidation treatment of carbamic acid, as shown in the curve B, the reduction wave Ic of oxygen rises in the vicinity of about −0.2 V (vs. Ag / AgCl). Is shifted to the positive potential side by about 0.2V. This is mainly because the superoxide anion (O ₂ ⁻ ) generated mainly by electrolytic reduction of oxygen is electrolytically decomposed to generate hydrogen peroxide ions. When platinum is supported after the electrolytic oxidation treatment of carbamic acid, as shown by curve C, the oxygen reduction wave Ic rises around +0.25 V (vs. Ag / AgCl). Further, it is shifted to the positive potential side. This is because of the oxygen reduction catalytic function of the platinum fine particles. Curves IIa and IIc are a hydrogen oxidation wave and a hydrogen ion reduction wave, respectively. These are the waves that appear as a result of carrying platinum. Therefore, in the case of electrodes supported on platinum, an electromotive force is generated by a combination of Ic of the oxygen reduction wave C and IIa of the hydrogen oxidation wave C. Similarly, when the amino group introduction electrode and the platinum supporting electrode are used for the cathode and the anode, an electromotive force is generated by the combination of B Ic and C IIa.

  As described above, when an amino group is introduced to the surface of a carbon electrode such as a glassy carbon electrode by a covalent bond, the reduction potential of oxygen is shifted to the positive potential side. For this reason, even if the amount of platinum, which is an oxygen reduction catalyst, is reduced, the reduction wave of oxygen can be shifted to a high potential. For example, the generated voltage of the battery can be kept high while reducing the cost of the electrode for the fuel cell. Can do.

Example 3
A carbon felt electrode was used as the carbon electrode, and cyclic voltammetry was performed to measure the reduction potential of oxygen. The conditions for cyclic voltammetry were the same as in Example 2. The 0.1M phosphate buffer containing the substance to be electrolyzed was prepared with dissolved oxygen and with nitrogen purged to have no dissolved oxygen.

  As the carbon felt electrode, a circular carbon felt electrode having a diameter of 5 mm (GC-20-5F manufactured by Nippon Carbon Co., Ltd., thickness 5 mm) was used, and a platinum wire was connected thereto. Other conditions were the same as in Example 1. Then, an aqueous ammonium carbamate solution was electrolytically oxidized to covalently bond an amino group to a carbon atom on the surface. Moreover, the carbon felt electrode which does not introduce | transduce an amino group was also used as a comparative example.

  FIG. 7 shows the measurement result of the reduction potential of oxygen using a carbon felt electrode without amino group introduction. In FIG. 7, when dissolved oxygen is present in the 0.1M phosphate buffer containing the substance to be electrolyzed (curve B), a small redox wave Ic near 0V and a large wave from around −0.4V appear. . On the other hand, in the cyclic voltammogram (curve A) obtained with the phosphate buffer deoxygenated by purging with nitrogen, a very small reduction wave appeared in the vicinity of 0V, whereas no reduction wave was observed in the vicinity of −0.4V. Not appearing.

  FIG. 8 shows the measurement result of the reduction potential of oxygen using a carbon felt electrode in which an amino group is covalently bonded to a surface carbon atom. In the data without dissolved oxygen in the phosphate buffer (curve A), a reduction wave b that did not appear in FIG. 7 appeared in addition to the same reduction wave a as Ic in FIG. This indicates that a redox species that becomes a reduction mediator of oxygen was newly introduced by the amino group introduction treatment. This is also indicated by the fact that when oxygen is present in the phosphate buffer (curve B), a new large reduction wave of oxygen is observed at the same position as b (IIc). The oxygen reduction mediator that causes the reduction wave a is a mediator that is not observed at all in glassy carbon, and is a phenomenon peculiar to carbon felt. Further, the oxygen reduction activity shown by the reduction wave a is greatly amplified by introducing an amino group. This can be seen from the fact that the magnitude of the reduction wave Ic of the curve B in the presence of dissolved oxygen in FIG. 8 is larger than the reduction wave Ic of the curve B in FIG.

  Further, comparing the curve B in FIG. 8 and the curve B in FIG. 7, it can be seen that the reduction wave Ic of oxygen is amplified by introducing the amino group as described above. The half wave potential of the amplified reduction wave Ic is about +0.05 V (vs. Ag / AgCl). On the other hand, since the standard redox potential of the hydrogen reduction reaction is −1.05 V (vs. Ag / AgCl), when a carbon felt electrode into which nitrogen atoms are introduced is used, the difference in redox potential between hydrogen and oxygen is about 1 .10V, indicating the same electromotive force as that of a fuel cell using a platinum-supported carbon electrode that is currently popular. Therefore, the same electromotive force as that of the conventional platinum-supported carbon electrode can be developed without supporting platinum.

  FIG. 9 shows a comparison result of oxygen reduction currents between the amino group-introduced carbon felt electrode and the platinum-supported carbon felt electrode. In FIG. 9, the curve A is the same data as the curve B of FIG. 8, and the curve B is the data of the platinum carrying carbon felt electrode. As shown in FIG. 9, by carrying platinum, the oxygen reduction waves Ic and IIc were larger than the data when platinum was not carried (B in FIG. 7), but the carbon felt electrode into which amino groups were introduced. It was smaller than the reduction waves Ic and IIc. As a result, it can be seen that the effect of increasing the oxygen reduction wave by introducing the amino group is greater than the effect of platinum support. The carbon felt electrode supported by platinum after the introduction of the amino group had almost the same data as B in FIG. 9, and the result that platinum inhibited the amino group introduction effect was obtained.

Example 4
The oxidation-reduction potential of hydrogen peroxide was measured using a glassy carbon electrode in which an amino group was covalently bonded to a surface carbon atom in the same manner as in Example 1.

  FIG. 10 shows the measurement result of the oxidation-reduction potential of hydrogen peroxide. In FIG. 10, curve A shows a case where a glassy carbon electrode in which an amino group is not covalently bonded to a surface carbon atom is used, and curve B shows a glassy carbon electrode in which an amino group is covalently bonded to a surface carbon atom. Each case is shown.

  As can be seen from the above curves A and B, the hydrogen peroxide reduction current value varies greatly depending on whether amino groups are introduced onto the surface. In the glassy carbon electrode into which amino groups are introduced, the rising potential of hydrogen peroxide reduction is reduced by oxygen reduction. It can be seen that the voltage shifts to −0.2 V (vs. Ag / AgCl) which is substantially the same as the rising potential. According to this, for example, in a fuel cell, hydrogen peroxide that degrades carbon and the diaphragm at the same potential as the oxygen reduction potential can be reduced at that potential, so that deterioration due to hydrogen peroxide can be avoided.

  In addition, it can be seen that the glassy carbon electrode into which an amino group has been introduced also greatly increases the electrolytic oxidation current (Ia) of hydrogen peroxide, and direct electrolytic oxidation is possible. Thus, it can be seen that this electrode can promote both reduction and oxidation of hydrogen peroxide.

  FIG. 11 shows the results of a constant potential electrolysis current measurement of hydrogen peroxide using a glassy carbon electrode in which an amino group is covalently bonded to a surface carbon atom in the same manner as in Example 1 (A ). As a comparative example, a constant potential electrolysis current of hydrogen peroxide using a glassy carbon electrode (B) electrolyzed with a phosphate buffer and a glassy carbon electrode (C) not subjected to electrolytic treatment (no amino group introduction) Measurements were also made. Here, the hydrogen peroxide used has a concentration of 0.088M, and these are added sequentially, and the addition amount is a: 50 microliters (μL), b: 100 μL, c: 150 μL, d: 200 μL, e: The constant potential electrolysis current was measured when 500 μL, f: 500 μL, and g: 1 mL. Constant potential electrolysis was performed at a potential of +0.85 V with respect to the Ag / AgCl reference electrode.

  In FIG. 11, it was revealed that the glassy carbon electrode (A) in which the amino group is covalently bonded to the surface carbon atom gives a larger electrolytic current than Comparative Examples B and C. From this result, it can be seen that the detection limit of hydrogen peroxide can be set to about 1 μM (micromol / liter). For this reason, the glassy carbon electrode in which the amino group of this embodiment is covalently bonded to the carbon atom on the surface can be applied to an electrochemical sensor or a biosensor that detects an electrolytic oxidation current of hydrogen peroxide. Conventionally, such electrochemical sensors and biosensors used noble metals such as gold and platinum as electrodes, but according to the present embodiment, there is no need to use noble metals, and low-cost electrochemical sensors and biosensors can be used. realizable.

Example 5 FIG.
A carbon felt electrode was used as the carbon electrode, and cyclic voltammetry of hydrogen peroxide was performed.

  FIG. 12 shows a cyclic voltammogram of the hydrogen peroxide. In FIG. 12, curve A is the result of using a carbon felt electrode on which no amino group was introduced on the electrode surface, and curve B used a carbon felt electrode on which an amino group was introduced in the same manner as in Example 1. It is a result. In addition, as a carbon felt electrode, Nippon Carbon Co., Ltd. carbon felt (GC-20-5F) was used.

  As shown in FIG. 12, a wave Ic reduced from around +0.3 V and a wave IIc reduced from around −0.2 V are separated from the Ag / AgCl reference electrode. Thereby, the reduction potential of oxygen can be further shifted to the higher potential side, and the electromotive force of the fuel cell or the like can be increased.

Example 6
In the same manner as in Example 1, the electrolytic reduction wave of hypochlorite ions was measured using a glassy carbon electrode in which an amino group was introduced on the surface with an electrolytic oxidation time of the ammonium carbamate aqueous solution being 3 hours.

  FIG. 13 shows the electrolytic reduction wave of the hypochlorite ion measured above. In FIG. 13, a curve A is a case where a glassy carbon electrode into which an amino group is not introduced is used as a comparative example, and a curve B is a case where a glassy carbon electrode into which an amino group is introduced is used.

  As shown in FIG. 13, in the case of a glassy carbon electrode into which no amino group has been introduced, the reduction wave Ic of hypochlorite ions appears below 0 V and overlaps with the reduction wave IIc of oxygen. It is extremely difficult to produce a typical hypochlorite ion sensor. In contrast, when a glassy carbon electrode into which an amino group is introduced is used, it can be seen that reduction can be performed from a potential of +0.6 V with respect to the Ag / AgCl reference electrode. For this reason, according to the glassy carbon electrode of a present Example, a highly selective hypochlorite ion sensor can be produced.

It is a figure which shows the structural example of the electrolytic oxidation apparatus of the ammonium carbamate aqueous solution. It is a figure which shows the time-dependent change of the electrolytic oxidation current at the time of implementing electrolytic oxidation of the ammonium carbamate aqueous solution. It is a figure which shows the result of having measured the surface of the glassy carbon electrode by X-ray photoelectron spectrophotometry. It is a figure which shows the mechanism in which the nitrogen atom of carbamic acid is introduce | transduced by the covalent bond on the surface of a glassy carbon electrode. It is a figure which shows the result of the cyclic voltammetry of the catechol performed with the glassy carbon electrode. It is a figure which shows the measurement result of the reduction potential of oxygen using a glassy carbon electrode. It is a figure which shows the measurement result of the reduction potential of oxygen using the carbon felt electrode which does not introduce | transduce an amino group. It is a figure which shows the measurement result of the reduction potential of oxygen using the carbon felt electrode which covalently bonded the amino group to the surface carbon atom. It is a figure which shows the comparison result of the oxygen reduction current of the carbon felt electrode which carried out the covalent bond of the amino group to the surface carbon atom, and a platinum carrying | support carbon felt electrode. It is a figure which shows the measurement result of the oxidation reduction potential of hydrogen peroxide using the glassy carbon electrode which covalently bonded the amino group to the surface carbon atom. It is a figure which shows the result of having performed the constant potential electrolysis current measurement of hydrogen peroxide using the glassy carbon electrode which covalently bonded the amino group to the surface carbon atom. It is a figure which shows the cyclic voltammogram of hydrogen peroxide using a carbon felt electrode. It is a figure which shows the measurement result of the electroreduction wave of a hypochlorite ion using the glassy carbon electrode which covalently bonded the amino group to the carbon atom of the surface.

Explanation of symbols

  10 plastic container, 12 working electrode, 14 counter electrode, 16 reference electrode, 18 potentiostat, 20 stirrer.

Claims (13)

  An electrode material, wherein a nitrogen-containing functional group is covalently bonded to the surface of a carbon material.   2. The electrode material according to claim 1, wherein the nitrogen-containing functional group is an amino group.   3. The electrode material according to claim 1, wherein the carbon material is a carbon material having conductivity.   4. The electrode material according to claim 3, wherein the carbon material is one of glassy carbon, carbon nanotube, carbon felt, plastic molded carbon, or diamond electrode.   A method for producing an electrode material, wherein an aqueous solution containing carbamic acid is electrolytically oxidized using a carbon electrode, and a nitrogen-containing functional group is covalently bonded to the surface of the carbon electrode.   6. The method for producing an electrode material according to claim 5, wherein the nitrogen-containing functional group is an amino group.   7. The method for producing an electrode material according to claim 5, wherein the aqueous solution containing carbamic acid is ammonium carbamate, ammonium carbonate, or ammonium hydrogen carbonate.   The electrode material according to any one of claims 1 to 4 or the electrode material produced by the method for producing an electrode material according to any one of claims 5 to 7 is used. Chemical sensor.   A fuel using the electrode material according to any one of claims 1 to 4 or the electrode material produced by the method for producing an electrode material according to any one of claims 5 to 7. Battery electrode.   A noble metal catalyst is supported on the electrode material according to any one of claims 1 to 4 or the electrode material produced by the method for producing an electrode material according to any one of claims 5 to 7. A feature of an oxygen reduction catalyst electrode.   The oxygen reduction catalyst electrode according to claim 10, wherein the noble metal catalyst is platinum.   A nitrogen-containing functional group covalently bonded to the surface of the electrode material according to any one of claims 1 to 4 or the electrode material produced by the method for producing an electrode material according to any one of claims 5 to 7. A biosensor characterized by chemically immobilizing a molecular recognition agent on the basis thereof. The biosensor according to claim 12, wherein the molecular recognition agent is an enzyme, a biocatalyst, an antigen, or an antibody.

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