Hydrogen peroxide decomposition catalyst electrode and method for producing same

Abstract

To provide a catalyst electrode that can decompose hydrogen peroxide by photocatalysis and catalysis and a method for producing the same.SOLUTION: A catalyst electrode for decomposing hydrogen peroxide has an n-type organic semiconductor layer provided on an electrode substrate, the n-type organic semiconductor layer having a catalytic promoter containing iron(III) oxide supported thereon. The catalyst electrode shows photocatalysis and catalysis for the oxidation of hydrogen peroxide and can efficiently oxidize hydrogen peroxide both under light irradiation and at a dark place. The catalyst electrode can be produced by a first step of providing an n-type organic semiconductor layer on an electrode substrate and a second step of allowing the n-type organic semiconductor layer to support iron(III) oxide thereon.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a catalytic electrode for decomposing hydrogen peroxide and a method for producing the same. [Background technology]

[0002] Hydrogen peroxide has a strong oxidizing ability and has excellent cleaning and bactericidal effects, so its aqueous solution is widely used as a cleaning agent, bactericide, etc. For example, in electronic device manufacturing plants, hydrogen peroxide aqueous solution is used for parts cleaning in various processes. The used hydrogen peroxide aqueous solution is discharged in wastewater from manufacturing plants, etc. However, hydrogen peroxide has a problem of being a source of COD, so it is necessary to decompose hydrogen peroxide before discharging it into rivers, etc. Conventionally, the decomposition process of hydrogen peroxide in wastewater requires the addition of reducing agents, enzymes, etc., and is time-consuming. To solve this problem, decomposition methods using photocatalysts have been provided, for example, as in Patent Documents 1 and 2. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-151451 [Patent Document 2] JP 2014-205103 A Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Documents 1 and 2 describe a method for decomposing hydrogen peroxide by contacting water to be treated that contains hydrogen peroxide with a photocatalyst such as titanium oxide while being irradiated with ultraviolet light. This method makes it unnecessary to add reducing agents or enzymes, and enables hydrogen peroxide in the liquid to be decomposed and removed efficiently and at low cost.

[0005] However, the method of using a photocatalyst to decompose hydrogen peroxide by its photocatalytic action cannot be used in a dark place as a matter of course. Therefore, an object of the present invention is to provide a catalytic electrode for the decomposition of hydrogen peroxide, which can decompose hydrogen peroxide both under light irradiation and in a dark place, and a method for producing the same. [Means for solving the problem]

[0006] The present inventors conducted intensive research to solve the above problems, and found that a catalyst electrode having an n-type organic semiconductor layer provided on an electrode substrate and an iron compound supported on the surface of the n-type organic semiconductor layer exhibits photocatalytic and catalytic effects on the oxidation of hydrogen peroxide, and can decompose hydrogen peroxide both under light irradiation and in the dark. Based on this finding, the inventors conducted further research and completed the present invention. That is, the above problems are solved by the invention having the following configuration.

[0007] [1] A catalytic electrode for decomposing hydrogen peroxide, which oxidizes hydrogen peroxide under light irradiation and in the dark, comprising: On top of the electrode substrate Made of perylene derivatives A catalytic electrode for the decomposition of hydrogen peroxide, comprising an n-type organic semiconductor layer and a co-catalyst containing iron (III) oxide supported on the n-type organic semiconductor layer. [2] A catalytic electrode for decomposing hydrogen peroxide, which oxidizes hydrogen peroxide under light irradiation and in the dark, comprising: On top of the electrode substrate Made of perylene derivatives An n-type organic semiconductor layer is provided on the n-type organic semiconductor layer. Iron(II) complex compound A catalytic electrode for the decomposition of hydrogen peroxide, characterized in that it supports an iron (III) oxide precursor. [3] A method for producing a catalytic electrode for decomposing hydrogen peroxide, which oxidizes hydrogen peroxide under light irradiation and in a dark place, comprising the steps of: On top of the electrode substrate Made of perylene derivatives A method for producing a catalytic electrode for the decomposition of hydrogen peroxide, comprising: a first step of providing an n-type organic semiconductor layer; and a second step of supporting iron oxide (III) on the n-type organic semiconductor layer. [4] The second step comprises: Iron(II) complex compound 1. A method for producing a catalytic electrode for the decomposition of hydrogen peroxide according to claim 3, comprising the steps of: supporting an iron(III) oxide precursor; and producing iron(III) oxide from the iron(III) oxide precursor. Effect of the Invention

[0008] According to the present invention, it is possible to provide a catalytic electrode for the decomposition of hydrogen peroxide, which exhibits photocatalytic and catalytic actions on the decomposition of hydrogen peroxide and is capable of decomposing hydrogen peroxide both under light irradiation and in the dark, and a method for producing the same. [Brief description of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing the configuration of a catalytic electrode for decomposing hydrogen peroxide of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing a configuration example in which the catalytic electrode for decomposing hydrogen peroxide of the present invention is used in a two-chamber electrolytic cell. [Diagram 3] 1 is an X-ray diffraction pattern of the catalytic electrode of Test Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention provides a catalyst electrode for the decomposition of hydrogen peroxide, which exhibits photocatalytic and catalytic actions for the decomposition of hydrogen peroxide and can decompose hydrogen peroxide both under light irradiation and in the dark, and a method for producing the same. Note that in this specification, the action of exhibiting photocatalytic and catalytic actions and catalyzing the same oxidation reaction both under light irradiation and in the dark is also referred to as dual catalysis. Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] <Catalyst electrode for hydrogen peroxide decomposition> The configuration of the catalytic electrode for the decomposition of hydrogen peroxide of the present invention is shown in Figure 1. The catalytic electrode for the decomposition of hydrogen peroxide 10 of the present invention has an n-type organic semiconductor layer 14 provided on an electrode substrate 12, and a co-catalyst 16 containing iron (III) oxide supported on the n-type organic semiconductor layer 14.

[0012] (electrode base material) The electrode substrate 12 is made of a material having electrical conductivity. Examples of the material include a conductive transparent glass substrate, a metal substrate, and a carbon-based substrate. Specific examples of the material include a conductive transparent glass substrate coated with indium-tin oxide (ITO), fluorine-doped tin oxide (FTO), or the like, and a carbon-based substrate such as graphite, diamond, or glassy carbon. The resistance value of the electrode substrate 12 is, for example, 5 to 100 Ω / cm. 2 , preferably 8 to 20 Ω / cm 2 The electrode substrate 12 may have a variety of shapes, but is preferably in the form of a plate having a large electrode surface area in order to increase the efficiency of light irradiation.

[0013] (n-type organic semiconductor layer) An n-type organic semiconductor layer 14 is provided on the surface of the electrode substrate 12. The n-type organic semiconductor layer 14 contains an n-type organic semiconductor material. The thickness of the n-type organic semiconductor layer is about 50 to 800 nm, and preferably about 100 to 650 nm.

[0014] The n-type organic semiconductor material is not particularly limited, and may be a perylene derivative, a naphthalene derivative, a fullerene, a carbon nanotube, a graphene, etc. Here, perylene derivatives, naphthalene derivatives, fullerene or fullerenes, graphene or graphenes refer to compounds having the basic skeleton of perylene, naphthalene, fullerene, and graphene, respectively. Particularly suitable n-type organic semiconductor materials are hexa-perihexabenzocoronene, 3,4,9,10-perylenetetracarboxyl-bisbenzimidazole or fullerenes (C 60 etc.), and carbon nanotubes.

[0015] (Co-catalyst) A promoter 16 is supported on the n-type organic semiconductor layer 14. The promoter 16 is iron(III) oxide (Fe 2 O 3). The promoter 16 may be in various shapes, such as a layer or a particulate shape. From the viewpoint of increasing the surface area, a particulate or porous shape is preferable. The promoter 16 does not need to completely cover the surface of the n-type organic semiconductor layer 16, and may be supported so as to cover only a portion of the surface.

[0016] <Decomposition of hydrogen peroxide> The catalytic electrode for decomposing hydrogen peroxide of the present invention configured as described above can decompose hydrogen peroxide by the same oxidation reaction by both photocatalysis and catalysis. That is, the catalytic electrode for decomposing hydrogen peroxide of the present invention is a single catalytic electrode, but exhibits dual catalysis for the decomposition of hydrogen peroxide. In addition, the catalytic electrode for decomposing hydrogen peroxide has a higher decomposition ability under light irradiation than in the dark. Thus, the catalytic electrode for decomposing hydrogen peroxide of the present invention functions both under light irradiation and in the dark, and can decompose hydrogen peroxide more effectively than conventional catalytic electrodes that only have photocatalysis.

[0017] Next, an example of the use of the catalytic electrode for decomposing hydrogen peroxide of the present invention will be described. For example, in a bipolar electrolytic cell in which a working electrode and a counter electrode are installed, an aqueous solution of hydrogen peroxide to be decomposed is placed in the electrolytic cell, and the catalytic electrode for decomposing hydrogen peroxide of the present invention is used as the working electrode. The electrolytic cell may be of various types, such as a single-chamber type or a two-chamber type, and may be of a three-electrode type by further installing a reference electrode. There is no limitation on the electrolysis method, and a method such as constant current electrolysis or constant voltage electrolysis may be selected.

[0018] 2 is a schematic diagram showing an example of a configuration in which the catalytic electrode 10 for decomposing hydrogen peroxide of the present invention is used in a two-chamber electrolytic cell 20. The two-chamber electrolytic cell 20 is composed of an anode chamber 22 and a cathode chamber 24 separated by a salt bridge 26. The anode chamber 22 is composed of a working electrode 30 immersed in a hydrogen peroxide solution 38. The catalytic electrode 10 for decomposing hydrogen peroxide of the present invention is used as the working electrode 30. The cathode chamber 24 is composed of a counter electrode 34 immersed in an electrolyte aqueous solution 32. The electrode substrate 12 of the working electrode 30 and the counter electrode 34 are connected to a power supply 40 by a conductor 42. In the case of a three-electrode type, for example, a reference electrode (not shown) is immersed in the electrolyte aqueous solution 32 in the cathode chamber 24 and connected to the power supply 40 by the conductor 42.

[0019] The hydrogen peroxide aqueous solution 38 is wastewater containing hydrogen peroxide to be decomposed, and can be used without any particular limitation on the concentration of hydrogen peroxide. The counter electrode 34 is a precious metal electrode such as a platinum electrode or a gold electrode. The electrolyte aqueous solution 32 is preferably an acidic aqueous solution containing an acid such as phosphoric acid or sulfuric acid. The pH of the electrolyte aqueous solution 32 is preferably 5 or less, and more preferably 2 or less. The power supply unit 40 is composed of a potentiostat, a function generator, a coulomb meter, and the like. Although there is no particular limitation on the light source (not shown) that irradiates the working electrode 30 with light, since the catalytic electrode of the present invention absorbs light having a wavelength of near infrared or less to exhibit photocatalytic activity, it is preferable to use a light source that includes light having a wavelength of about 1200 nm or less. As the light source, for example, sunlight, a halogen lamp, a xenon lamp, a mercury lamp, a fluorescent lamp, an LED, or the like can be suitably used. In this configuration, the catalytic electrode 10 for the decomposition of hydrogen peroxide of the present invention is capable of oxidatively decomposing hydrogen peroxide in an aqueous hydrogen peroxide solution 38, regardless of the presence or absence of light irradiation. Hydrogen peroxide can be decomposed without applying a potential to the catalytic electrode 10 for the decomposition of hydrogen peroxide of the present invention (working electrode 30), but a potential may be applied by a power supply unit 40 as appropriate for the purpose of further increasing the decomposition rate, etc. When applying a potential, a potential is applied between the catalytic electrode 10 for the decomposition of hydrogen peroxide and the counter electrode 34 in the case of a two-electrode type, and between the catalytic electrode 10 for the decomposition of hydrogen peroxide and a reference electrode in the case of a three-electrode type.

[0020] The mechanism by which the catalytic electrode for the decomposition of hydrogen peroxide of the present invention exhibits dual catalysis with respect to the oxidation of hydrogen peroxide is presumed to be as follows. (Oxidation by photocatalysis) When light is irradiated onto the catalytic electrode of the present invention, excited electrons and holes are generated due to light absorption by the n-type organic semiconductor layer. The holes move to the cocatalyst iron oxide (III) and induce the oxidation of hydrogen peroxide on the surface of the iron oxide (III). The excited electrons are transported to the counter electrode via the conductor. (Oxidation by catalytic action) In the dark, iron oxide (III) acts as a normal catalyst (thermal catalyst) and induces the oxidation of hydrogen peroxide. Electrons released from hydrogen peroxide as it oxidizes are transported to the counter electrode via iron oxide (III), the n-type organic semiconductor layer, and the conductor wire, for example, in an electrolytic cell configured as shown in Figure 2. Due to the mechanism described above, the catalytic electrode for the decomposition of hydrogen peroxide of the present invention can decompose hydrogen peroxide both under light irradiation and in the dark, and the electrons released by the oxidation of hydrogen peroxide induce various reduction reactions depending on the conditions in the cathode chamber.

[0021] <Method of manufacturing catalytic electrode for hydrogen peroxide decomposition> The method for producing a catalytic electrode for decomposing hydrogen peroxide of the present invention includes a first step of providing an n-type organic semiconductor layer on an electrode substrate, and a second step of supporting iron (III) oxide on the n-type organic semiconductor layer. The details are described below.

[0022] (1st step) In the first step, an n-type organic semiconductor layer made of an n-type organic semiconductor material is provided on an electrode substrate. As described above, a conductive material such as a conductive transparent glass substrate is used as the electrode substrate. As described above, perylene derivatives, naphthalene derivatives, fullerenes, carbon nanotubes, graphenes, etc. are used as the n-type organic semiconductor material. Examples of methods for providing an n-type organic semiconductor layer on an electrode substrate include vacuum deposition, sputtering, electrochemical coating (electrodeposition), and coating. Among these, the vacuum deposition method can be preferably used to achieve uniform coating.

[0023] (2nd process) In the second step, iron oxide (III) is supported on the n-type organic semiconductor layer. There are two methods for supporting iron oxide (III) on the n-type organic semiconductor layer:

[0024] In the first method, iron oxide (III) obtained by a known method is directly supported on the n-type organic semiconductor layer 12. Iron oxide (III) can be in the form of powder or lumps. Methods for supporting iron oxide (III) include sputtering and coating. For example, when coating, powdered iron oxide (III) is dispersed in water or alcohol, and the dispersion is applied to the n-type organic semiconductor layer and dried to support the layer. In this way, a catalytic electrode for decomposing hydrogen peroxide according to the present invention is obtained.

[0025] The second method includes a step of supporting an iron(III) oxide precursor on an n-type organic semiconductor layer, and a step of producing iron(III) oxide from the iron(III) oxide precursor.

[0026] As the iron(III) oxide precursor, iron compounds such as iron(II) hydroxide, iron(III) hydroxide, and iron oxyhydroxide, as well as iron salts such as iron(III) oxalate, iron(III) nitrate, and iron chloride, and iron organic compounds such as iron complex compounds such as iron(II) phthalocyanine and iron(II) porphyrin can be used. These can be obtained by known methods and may be used alone or as a mixture.

[0027] The method of supporting the iron (III) oxide precursor on the n-type organic semiconductor layer is appropriately selected from vacuum deposition, sputtering, electrochemical coating (electrodeposition), coating, etc., depending on the iron (III) oxide used. For example, when iron (II) hydroxide, iron (III) hydroxide, iron oxyhydroxide, etc. are used, the powder (or fine particles) of the precursor is dispersed in water or alcohol, and the dispersion is applied to the n-type organic semiconductor layer and dried to support the precursor. Water-soluble iron (III) oxide precursors such as iron salts are supported by applying their aqueous solutions to the n-type organic semiconductor layer and drying the aqueous solutions. Here, the iron salt may be converted to an insoluble iron compound such as iron hydroxide or iron oxyhydroxide by immersing the catalytic electrode in an alkaline solution after coating or drying, and then supported. Iron organic compounds such as iron (II) phthalocyanine and iron (II) porphyrin can be supported on the n-type organic semiconductor layer by the above-mentioned methods, for example, vacuum deposition, sputtering, electrochemical coating (electrodeposition), etc. The catalytic electrode having an iron (III) oxide precursor supported on an n-type organic semiconductor layer obtained here will be described in detail in the section on other embodiments of the catalytic electrode of the present invention.

[0028] Next, iron(III) oxide is generated from the supported iron(III) oxide precursor. The method for generating iron(III) oxide may be appropriately selected depending on the supported iron(III) oxide precursor, such as thermal decomposition, oxidation with an oxidizing agent, or a combination of these.

[0029] For example, when a precursor that generates iron oxide (III) when heated, such as iron compounds such as iron hydroxide (III) or iron oxyhydroxide, or iron salts, is supported, a method using thermal decomposition can be preferably used. By heating a catalytic electrode supporting an iron oxide (III) precursor, the iron oxide (III) precursor is decomposed to generate iron oxide (III), and the catalytic electrode for decomposing hydrogen peroxide of the present invention in which iron oxide (III) is supported on an n-type organic semiconductor layer is obtained. The heating temperature is appropriately selected depending on the precursor, for example, when iron oxyhydroxide is used, heating is performed to about 190°C or higher. By carrying out the same treatment in the presence of an oxidizing agent such as oxygen, iron oxide (III) can also be obtained from iron (II) compounds such as iron hydroxide (II).

[0030] In addition, when an iron(II) complex compound such as iron(II) phthalocyanine or iron(II) porphyrin is supported as an iron(III) oxide precursor, iron(III) oxide can be produced by contacting the iron(II) complex compound with an oxidizing agent. Examples of the oxidizing agent include inorganic peroxides such as ozone, hydrogen peroxide, calcium peroxide, sodium peroxide, and permanganate, and organic peroxides such as peracetic acid and t-butyl hydroperoxide. The contact with the oxidizing agent is carried out by immersing the catalytic electrode carrying the iron(II) complex compound in an aqueous solution containing the oxidizing agent. As a result, the iron(II) in the iron(II) complex compound is oxidized by the oxidizing agent to generate iron(III) oxide, which is then supported on the n-type organic semiconductor layer, thereby obtaining the catalytic electrode for decomposing hydrogen peroxide of the present invention. Here, when hydrogen peroxide is used as the oxidizing agent, the Fenton reaction generates a radical species (·OH) along with the oxidation of iron(II), and this radical species decomposes the cyclic organic matter, facilitating the generation of iron(III) oxide, which is preferable. The aqueous hydrogen peroxide solution in which the catalytic electrode is immersed may be wastewater containing hydrogen peroxide to be decomposed. In this way, the catalytic electrode for the decomposition of hydrogen peroxide of the present invention can be obtained by an in-situ reaction without the need to separately prepare an aqueous hydrogen peroxide solution, and the hydrogen peroxide can be subsequently decomposed.

[0031] <Other aspects of catalytic electrodes for hydrogen peroxide decomposition> Another embodiment of the catalytic electrode for hydrogen peroxide decomposition of the present invention is an electrode substrate having an n-type organic semiconductor layer on which an iron (III) oxide precursor is supported. The iron (III) oxide precursor can be preferably an iron (II) complex compound such as iron (II) phthalocyanine or iron (II) porphyrin, which can be oxidized by hydrogen peroxide to generate iron (III) oxide. When the catalytic electrode thus configured is immersed in an aqueous solution containing hydrogen peroxide to be decomposed, iron (III) oxide is generated from the iron (III) oxide precursor such as an iron (II) complex compound by an in-situ reaction as described above, and dual catalysis is exhibited against the oxidation of hydrogen peroxide. Therefore, it can be said that the catalytic electrode can be preferably used for decomposing hydrogen peroxide while omitting some of the manufacturing steps of the catalytic electrode for hydrogen peroxide decomposition. EXAMPLES

[0032] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0033] <Creating a catalytic electrode for hydrogen peroxide decomposition> Example 1 The electrode base material is a conductive transparent glass substrate (ITO substrate) coated with indium tin oxide (ITO) (manufactured by Asahi Glass Co., Ltd., resistance 8 Ω / cm 2 ) was used. The ITO substrate was cut to 1.5 cm x 1 cm, and a conductive wire was attached to a 0.5 cm x 1 cm section using a silver-containing epoxy adhesive (Fujikura Chemical Industries, Ltd., D-500). Furthermore, the silver part (the surface of the hardened adhesive) was covered with an epoxy adhesive to insulate it from contact with the electrolyte aqueous solution.

[0034] Next, an n-type organic semiconductor layer was formed on the ITO substrate with the conductive wire attached by vacuum deposition. The n-type organic semiconductor material was a perylene derivative, 3,4,9,10-perylenetetracarboxyl-bisbenzimidazole (PTCBI). The ITO substrate with the conductive wire attached was placed in a vacuum deposition apparatus (ULVAC Kiko Co., Ltd., VPC-260) and vacuum was set at approximately 1.0×10. -3PTCBI was laminated to a thickness of about 230 nm on the ITO-coated side of the ITO substrate under conditions of 0.03 Pa and a deposition rate of 0.03 nm / sec. Iron (II) phthalocyanine (FePc) was then laminated to a thickness of about 45 nm on the PTCBI layer by vacuum deposition. The resulting catalyst electrode (ITO / PTCBI / FePc) was designated as Example 1.

[0035] Comparative Example 1 A catalyst electrode (ITO / PTCBI) having only a PTCBI layer provided on an ITO substrate was prepared in the same manner as in Example 1, and used as Comparative Example 1.

[0036] <Evaluation of hydrogen peroxide decomposition ability> (Experimental equipment and methods) The hydrogen peroxide decomposition experiment was carried out using a two-chamber electrolytic cell (two-electrode type) separated by a salt bridge, as shown in Figure 2. The two-chamber electrolytic cell was configured as follows. First, the salt bridge was prepared as follows: 1.3 g of agar and 4.74 g of potassium nitrate were added to approximately 10 mL of distilled water, dissolved in a hot water bath, poured into the bridged area of ​​the two-chamber cell, and cooled to solidify. Next, the catalytic electrode of Example 1 or Comparative Example 1 was placed in the anode chamber as a working electrode, and a platinum wire was placed in the cathode chamber as a counter electrode. As the electrolyte aqueous solution, a 100 mmol / L hydrogen peroxide aqueous solution (pH=12) was placed in the anode chamber (working electrode side), and a 1 mmol / L methylene blue aqueous solution (pH=2) was placed in the cathode chamber (counter electrode side). The counter electrode, reference electrode, and working electrode were connected to a potentiostat (HA-301, manufactured by Hokuto Denko Corporation). Furthermore, a function generator (HB-104, manufactured by Hokuto Denko Corporation) and a coulomb meter (HF-201, manufactured by Hokuto Denko Corporation) were connected to the potentiostat. Prior to the experiment, argon gas was passed through the anode chamber and the cathode chamber for 30 minutes to remove the dissolved oxygen in the electrolyte aqueous solution. A light intensity of 100mW / cm2 was applied from the uncoated side of the ITO substrate of the catalytic electrode. 2The catalytic reaction was carried out for 3 hours with no potential applied, and the catalytic reaction was carried out in a dark place (without light irradiation) in the same way. In this experimental system, when hydrogen peroxide is oxidized and decomposed, the electrons generated by the oxidation of hydrogen peroxide are transported to the counter electrode, where methylene blue is reduced, producing colorless leuco methylene blue. After the reaction, the methylene blue concentration was measured from the absorbance at 664 nm using a spectrophotometer (PerkinElmer, Lambda-25) to calculate the amount of decomposed methylene blue, and the decomposition rate of hydrogen peroxide was calculated based on this.

[0037] (Evaluation Results) The catalytic electrodes of Example 1 and Comparative Example 1 were evaluated for their hydrogen peroxide decomposition rates under light irradiation or in the dark. The results are shown in Table 1. [Table 1]

[0038] When the catalytic electrode of Example 1 was used, reductive decomposition of methylene blue accompanied by oxidative decomposition of hydrogen peroxide was confirmed both under light irradiation and in the dark. The rate of hydrogen peroxide decomposition was higher under light irradiation than in the dark (Table 1). From these results, it was confirmed that the catalytic electrode of Example 1 exhibits dual catalysis for the oxidative decomposition of hydrogen peroxide. When the catalytic electrode of Comparative Example 1 was used, reductive decomposition of methylene blue accompanied by oxidation of hydrogen peroxide was confirmed under light irradiation. However, the amount of hydrogen peroxide decomposed in the dark was very small. From this result, it was confirmed that the catalytic electrode of Comparative Example 1 exhibits photocatalytic action on the decomposition of hydrogen peroxide, but exhibits almost no catalytic action in the dark. Moreover, both under light irradiation and in the dark, Example 1 exhibited a higher hydrogen peroxide decomposition rate than Comparative Example 1. Thus, it can be said that the catalytic electrode for the decomposition of hydrogen peroxide of the present invention functions both under light irradiation and in the dark, and can decompose hydrogen peroxide more effectively than a conventional catalytic electrode having only a photocatalytic action such as Comparative Example 1.

[0039] (Test Example 1) Next, in order to verify the structure of the catalytic electrode of Example 1, a catalytic electrode (ITO / FePc) was obtained by laminating only FePc on an ITO substrate in the same manner as in Example 1, and this was used as Test Example 1.

[0040] The catalytic electrode of Test Example 1 was immersed for 3 hours in a 100 mmol / L aqueous hydrogen peroxide solution (pH=12) from which dissolved oxygen had been removed by passing argon gas through the solution for 30 minutes while irradiating the solution with light. The electrode was evaluated before and after immersion using an X-ray diffraction apparatus (Rigaku Corporation, SmartLab 9kW, radiation source: CuKα). As a result, a peak was observed around 7° attributable to FePc in the catalytic electrode before immersion in hydrogen peroxide (Figure 3(a)), but after immersion, the peak disappeared, and the electrode was considered to be FePc. 2 O 3 , Fe(OH) 3 Peaks attributable to Fe, FeO, and Fe were observed (Fig. 3(b)). 2 O 3 The peak of α-type iron(III) oxide (α-Fe 2 O 3 ) or ε-type iron(III) oxide (ε-Fe 2 O 3 From the above X-ray diffraction results, it was found that when FePc is exposed to hydrogen peroxide, the phthalocyanine is decomposed and iron(III) oxide (Fe 2 O 3 It was found that iron species such as ) were produced.

[0041] Considering this result, it is believed that FePc is decomposed when immersed in hydrogen peroxide in Example 1 as well, and iron species such as iron oxide (III) are generated. In addition, considering the pH-potential diagram of iron, of the observed iron species, only iron oxide (III) can exist stably under the conditions of this example. Therefore, it is believed that the catalytic electrode of Example 1 has a structure in which iron oxide (III) is supported on PTCBI during hydrogen peroxide decomposition, and that dual catalysis occurs when iron oxide (III) acts as a promoter. Furthermore, from the above results, it can be said that the catalytic electrode having an iron (II) complex compound (FePc) supported on an n-type organic semiconductor (PTCBI) layer is a catalytic electrode for the decomposition of hydrogen peroxide that exhibits dual catalysis through an in situ reaction. [Explanation of symbols]

[0042] 10. Hydrogen peroxide decomposition catalytic electrode 12 Electrode base material 14 n-type organic semiconductor layer 16 Cocatalyst

Claims

1. A catalytic electrode for the decomposition of hydrogen peroxide, which oxidizes hydrogen peroxide under light irradiation and in a dark place, characterized in that an n-type organic semiconductor layer made of a perylene derivative is provided on an electrode substrate, and a co-catalyst containing iron oxide (III) is supported on the n-type organic semiconductor layer.

2. A catalytic electrode for the decomposition of hydrogen peroxide that oxidizes hydrogen peroxide under light irradiation and in a dark place, characterized in that an n-type organic semiconductor layer made of a perylene derivative is provided on an electrode substrate, and an iron (III) oxide precursor made of an iron (II) complex compound is supported on the n-type organic semiconductor layer.

3. A method for manufacturing a catalytic electrode for the decomposition of hydrogen peroxide, which oxidizes hydrogen peroxide under light irradiation and in a dark place, comprising: a first step of providing an n-type organic semiconductor layer made of a perylene derivative on an electrode substrate; and a second step of supporting iron oxide (III) on the n-type organic semiconductor layer.

4. 4. The method for producing a catalyst electrode for decomposing hydrogen peroxide according to claim 3, wherein the second step comprises: supporting an iron (III) oxide precursor made of an iron (II) complex compound on the n-type organic semiconductor layer; and generating iron (III) oxide from the iron (III) oxide precursor.

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