TW201903209A - Electrode base material, and electrode catalyst and electrolysis apparatus each using same - Google Patents

Abstract

The purpose of the present invention is to provide: a copper-based base material which is suitable for use as a base material for catalysts for hydrogen generation by means of electrolysis of water or catalysts for conversion of carbon dioxide into a carbon-containing substance by means of cathodic reduction, and which is capable of improving the catalytic performance of the catalysts; and an electrode catalyst and an electrolysis apparatus, each of which uses this copper-based base material. An electrode base material according to the present invention comprises: a substrate which is formed of copper or a copper alloy; and a diffusion prevention layer which is formed on the surface of the substrate directly or with an oxide layer being interposed therebetween, and which is formed from an organic material.

Description

Electrode substrate, electrode catalyst and electrolysis device using same

The present invention relates to an electrode substrate, and an electrode catalyst and an electrolysis device using the same.

In Japan, where energy resources are scarce, there are plans to produce hydrogen and use it for various fuels in the future. Increase the renewable energy generated by solar cells, water, wind, etc., and use hydrogen from water or steam to produce hydrogen instead of fossil fuel.

Furthermore, the recent adverse effects caused by global warming have brought about various changes in the global environment, and many problems have been discovered. The reason is that warm gas, especially the concentration of carbon dioxide, which accounts for most of it, rises. In order to reduce the concentration of carbon dioxide, not only the use of new land afforestation and marine algae to increase the amount of photosynthesis, but also the active absorption and recovery of carbon dioxide, and the use of carbon as a raw material for organic compounds, and fixed to valuables for more than 10 years. Specifically, it is necessary to reduce carbon dioxide and convert it into carbon monoxide, methane, methanol, formic acid, etc., and use it as a material which can be used as a raw material for organic synthesis.

In recent years, in the reduction reaction of carbon dioxide as described above, a catalyst such as a photocatalyst or an electrode catalyst is widely used, and it is expected to develop a catalyst having more excellent catalyst performance.

The catalyst used for the carbon dioxide reduction reaction is not only a reaction efficiency but also a selectivity to a specific reaction, and from this viewpoint, the selection of materials is important (Non-Patent Document 1). For example, in order to reduce the carbon monoxide efficiently and increase the proportion of the reducing substance, it is recommended to use gold or silver for the catalyst material, and if it is efficiently reduced to produce hydrocarbons such as methane, ethane or ethylene, the catalytic material is used. Copper is recommended. In particular, copper is also attracting attention as a cathode reduction electrode catalyst for carbon dioxide because it can also generate a high-order organic substance such as ethylene.

As a reduction electrode catalyst for such a copper, in addition to a flat type such as a copper plate or a copper foil, a sieve or a porous shape is proposed (Patent Documents 1 and 2), and electrodeposition or evaporation is also used. A copper electrode catalyst formed by immobilizing a catalyst material on a substrate. However, such a copper electrode catalyst, the catalyst material formed on the substrate and the atoms constituting the substrate react or diffuse with each other over time, resulting in integration or modification with the substrate, resulting in The case where the catalyst performance expected as a catalyst material cannot be volatilized. [Previous Technical Literature]

[Patent Document 1] Japanese Laid-Open Patent Publication No. 2001-97894 [Patent Document 2] Japanese Patent No. 5,683,883 [Non-Patent Document]

[Non-Patent Document 1] Y Hori "Electrochemical reduction of CO at a Copper Electrode." J. Phys. Chem. B. 101(36). 7075-7081 (1997)

(The subject to be solved by the invention)

The present invention has been made in view of the above problems, and an object thereof is to provide a catalyst substrate suitable for hydrogen generation by water electrolysis or cathode reduction of carbon dioxide to be converted into a carbonaceous material, which can improve the catalytic performance of the catalyst. An electrode substrate, and an electrode catalyst and an electrolysis device using the same. (means to solve the problem)

In order to solve the above problems, the inventors of the present invention have intensively studied and found that a matrix composed of copper or a copper alloy is formed, and a diffusion preventing layer composed of an organic material is formed directly or via an oxide layer on the surface of the substrate. The copper-based substrate can be used to suppress or prevent the change of the catalyst material formed on the substrate by using a catalyst substrate which is converted into a carbonaceous material by electrolysis of water or by cathodic reduction of carbon dioxide. The catalyst for exhibiting excellent catalyst performance can be obtained, and the present invention has been completed based on this finding.

That is, the gist of the present invention is as follows. [1] An electrode substrate comprising a substrate and a diffusion preventing layer, wherein the substrate is made of copper or a copper alloy; the diffusion preventing layer is formed directly or via an oxide layer on the surface of the substrate, and contains an organic material. . [2] An electrode substrate which is a constituent substrate which is used to generate hydrogen by electrolysis using water or to reduce carbon dioxide by catalytic reduction of carbon dioxide. [3] The electrode substrate according to the above [1], wherein the organic material is an azole compound. [4] The electrode substrate according to any one of [1] to [3] wherein the electric double layer capacitance has a reciprocal value of 0.3 to 5 cm ² /μF. [5] An electrode substrate having an electrode substrate and a catalyst layer, wherein the electrode substrate is the electrode substrate according to any one of the above [1] to [4]; On the diffusion preventing layer of the electrode substrate, a catalyst material having a metal cluster is contained. [6] The electrode catalyst according to the above [5], wherein the metal cluster is a cluster composed of copper or a copper-based alloy. [7] The copper-based substrate according to any one of the above [1] to [4], wherein the electrode catalyst according to the above [5] or [6] is provided. [8] An electrolysis apparatus comprising: a cathode, a catholyte, an anode, the anolyte, and the anode and the anode provided in the copper substrate according to any one of the above [1] to [4] Inter-ion exchange membrane. [Effect of the invention]

According to the present invention, it is suitable for a substrate which is converted into a catalyst for a carbonaceous material by hydrogen production by water electrolysis or by cathodic reduction of carbon dioxide. According to such an electrode substrate, a catalyst which exhibits good catalyst performance for water electrolysis and cathode reduction of carbon dioxide can be obtained.

Embodiments of the electrode substrate of the present invention, and an electrode catalyst and an electrolysis device using the same will be described in detail below.

The electrode substrate of the present embodiment includes a substrate made of copper or a copper-based alloy, and a diffusion preventing layer formed of an organic material directly or via an oxide layer on the surface of the substrate. The copper-based electrode substrate is suitably used as a copper-based electrode substrate which constitutes a catalyst for hydrolyzing hydrogen in water or a catalyst for catalytically reducing a cathode to a carbonaceous material.

Fig. 1 is a schematic cross-sectional view showing a cross section of a copper-based substrate of the present embodiment. As shown in FIG. 1, the copper base material 1a of the present invention is provided with a base 11 and a diffusion preventing layer 13 formed directly on the base 11. 2 shows another example of the copper base material of the present embodiment, and FIG. 2 shows that the copper base material 1b is provided with the oxide layer 12 between the base 11 and the diffusion preventing layer 13. In the following, the copper base material 1a shown in FIG. 1 and the copper base material 1b shown in FIG. 2 are simply referred to as "copper base material 1" unless otherwise specified.

In addition, when the copper-based substrate of the present embodiment is used as a substrate constituting a catalyst, for example, the use form shown in FIG. 3 can be mentioned. FIG. 3 is a schematic cross-sectional view showing a cross section of the catalyst 3 using the copper base material 1a shown in FIG. 1 as an example of the case where the copper base material of the present embodiment is used as a catalyst base material. 3 shows that the catalyst 3 is formed on the diffusion preventing layer 13 of the copper-based substrate 1a. In addition, when the copper base material 1b shown in FIG. 2 is used as a base material, similarly to the catalyst 3 shown in FIG. 3, the catalyst layer 31 is formed to prevent diffusion of the copper base material 1b. On layer 13.

The copper-based substrate 1 of the present embodiment used as described above has a diffusion preventing layer 13 formed directly on the substrate 11 or via the oxide layer 12, and when a substrate as the catalyst 3 is used, The catalyst performance of the catalyst layer 31 is not deteriorated. In other words, according to the copper-based substrate 1, since the catalyst layer 31 is formed on the diffusion preventing layer 13, the catalyst material constituting the catalyst layer 31 does not directly contact the constituent components of the substrate 11, the oxide layer 12, and the like. . Therefore, it is possible to effectively prevent temporal reaction or mutual diffusion with atoms constituting the substrate 11, the oxide layer 12, and the like. As a result, the use of the copper-based substrate 1 of the present embodiment can effectively suppress the problem that the catalyst material of the conventional substrate is integrated with the substrate or deteriorates over time due to the modification, so that the catalyst material can be sufficiently and continuously exhibited. Catalyst performance.

The diffusion preventing layer 13 is made of an organic material. When the copper-based substrate 1 is used as a substrate of the catalyst 3, the organic material can effectively prevent the constituent materials of the catalyst material constituting the catalyst layer 31, the substrate 11, the oxide layer 12, and the like. An organic material which undergoes a reaction with time or a mutual diffusion may be used, and a material which can block the movement of a component between the substrate 11 and the oxide layer 12 and the catalyst layer 31 is more preferable. Examples of such a material include azoles such as triazoles, thiazoles, and imidazoles; and compounds such as thiols and triethanolamines. Among them, from the viewpoint of good affinity with copper (for example, coordination bonding to copper), azoles, more preferably triazoles, and particularly preferably benzotriazoles are preferred. Further, the benzotriazole compound is preferably, for example, benzotriazole.

The formation state of the diffusion preventing layer 13 is not particularly limited, and may be appropriately selected in accordance with the shape and use form of the substrate 11, and may be formed on at least one surface of the substrate 11, or may be formed to cover the entire surface of the substrate 11. status.

Furthermore, the thickness of the diffusion preventing layer 13 is quantitatively expressed in terms of the inverse value of the electric double layer capacitor. Specifically, the electric double layer capacitance reciprocal value indicating the thickness of the diffusion preventing layer 13 is measured using a commercially available direct reading type electric double layer capacitance measuring device (for example, impedance analyzer C, manufactured by Hioki Electric Co., Ltd.). The electric double layer capacitance (C: μF) of the surface, and the inverse value (1/C) is calculated according to the following formula (1). 1/C=A‧d+B (1) (d is the thickness of the electric double layer formed on the substrate, A and B are constant)

The reciprocal value of the electric double layer capacitor obtained by the above formula (1) is induced in proportion to the thickness d of the electric double layer formed on the substrate, that is, the thickness of the diffusion preventing layer 13. Therefore, the reciprocal value of such an electric double layer capacitor is preferably 0.3 to 5 cm ² /μF, more preferably 0.5 to 1.5 cm ² /μF. By setting it within the above range, when a substrate which is a catalyst is used, a catalyst capable of exhibiting excellent catalyst performance can be obtained. Further, when the reciprocal value of the electric double layer capacitor is 0.3 to 5 cm ² /μF, the thickness of the diffusion preventing layer 13 is measured by an electron microscope to an average of 4 to 75 nm.

The base 11 is made of copper or a copper alloy. When the base 11 is made of copper (pure copper), for example, a refined copper TPC, a phosphorus deoxidized copper PDC, an oxygen-free copper OFC may be processed into various shapes, or an electrolytic copper foil may be used. Further, when the base 11 is made of a copper-based alloy, for example, a copper-based diluted alloy such as a copper-tin alloy, a copper-iron alloy, a copper-zirconium alloy, or a copper-chromium alloy may be used, or A copper-based diluted alloy which is solidified or precipitated and strengthened by using a composition of a second component such as a Corson alloy or the like in an amount of from 0.01% by mass to 5% by mass. In addition, in the case of the alloy-based electrode, the amount of the component other than the silver is increased, the lower the conductivity, the lower the basic characteristics when the substrate electrode is formed, and the smaller the amount of components other than silver. The better. Further, the shape of the base 11 is not particularly limited, and a mesh or a porous shape may be used in addition to the flat plate shape, and a flat plate shape is particularly preferable.

The oxide layer 12 is formed between the substrate 11 and the diffusion preventing layer 12 in an arbitrary layer. The oxide layer 12 is preferably composed of, for example, a metal oxide layer, and more preferably contains an oxide of at least one metal selected from the transition metals, particularly preferably a copper-containing oxide. In addition to copper oxide, such as cuprous oxide (Cu ₂ O) or copper oxide (CuO), for example, copper oxide or the like may be determined. In particular, the oxide layer 12 preferably contains at least one of cuprous oxide or copper oxide.

Further, the oxide layer 12 may be a single layer composed of one oxide layer or a multiple layer composed of two or more oxide layers. Further, when the oxide layer 12 is a single layer composed of one oxide layer, a layer composed of one type of oxide or a layer in which two or more kinds of oxides are mixed may be used. Further, when the oxide layer 12 is a composite layer composed of two or more oxide layers, each layer is not necessarily an individual layer, and the respective oxides constituting each layer may be mixed at the boundary portion of the two layers. Further, in the oxide layer 12, in addition to various oxides, the organic material or the metal or alloy constituting the substrate may be contained in an amount of about 500 to 1000 ppm.

Further, the oxide layer 12 preferably contains at least cuprous oxide or copper oxide. The oxide layer 12 may, for example, be a single layer containing at least one of cuprous oxide and copper oxide, or a layer composed of cuprous oxide (hereinafter referred to as "copper oxide layer"), and oxidized. A multilayer of at least one of the layers of copper (hereinafter referred to as "copper oxide layer").

Further, the oxide layer 12 is preferably composed of two or more copper oxide layers having different copper oxidation numbers, and more preferably composed of a cuprous oxide layer and a copper oxide layer. Moreover, it is preferable that the copper oxide layer of the two or more layers has a larger copper oxidation number of the layer located on the surface side.

In the case where the oxide layer 12 is a stratified layer, FIG. 2 is a schematic cross-sectional view showing a cross section of the copper-based substrate 1b of the present embodiment. In the copper base material 1b shown in Fig. 2, the oxide layer 12 is composed of a first copper oxide layer 121 and a second copper oxide layer 122 having mutually different copper oxidation numbers. Here, the copper oxidation number of the second copper oxide layer 122 located on the surface side of the first copper oxide layer 121 is preferably larger than that of the first copper oxide layer 121.

For example, in FIG. 2, when the first copper oxide layer 121 is a cuprous oxide layer and the second copper oxide layer 122 is a copper oxide layer, the copper oxide layer is preferably located on the outermost layer than the cuprous oxide layer. Further, the thickness ratio of the cuprous oxide layer to the copper oxide layer is preferably 0.0001 to 10,000, more preferably 1 to 10,000.

Next, a preferred method of producing the copper-based substrate of the present embodiment will be described. The method for producing a copper-based substrate of the present embodiment includes the step of forming a diffusion preventing layer on the surface of the substrate. Moreover, the method further includes a pre-processing step and a step of forming an oxide layer. Hereinafter, specific description will be given.

(Pre-Processing Step) First, a substrate made of copper or a copper-based alloy is prepared, and the surface of the substrate is washed. By purifying the surface of the substrate, a diffusion preventing layer can be uniformly formed on the surface of the substrate in the subsequent step, and the adhesion between the substrate and the diffusion preventing layer can be improved. The surface washing can be carried out in accordance with a known method, but it is preferred to carry out acid washing (neutralization) after performing immersion degreasing or cathodic electrolytic degreasing.

(Step of Forming Diffusion Preventing Layer) A diffusion preventing layer is formed on the surface of the substrate which has been subjected to the pretreatment. Specifically, the substrate is immersed in a solution containing an organic material to form a diffusion preventing layer, and dried to form a diffusion preventing layer on the substrate.

As the organic material, the above organic material can be used. Further, as the solvent of the solution containing the organic material, a known solvent such as water or alcohol can be used. Further, when the substrate is immersed, the temperature of the solution containing the organic material may be 60 to 100 ° C, the immersion time may be 1.5 to 4 minutes, or the drying temperature may be 60 to 90 °C. Further, the thickness of the diffusion preventing layer can be adjusted by the type of the organic material, the solution concentration, and the number of times of the immersion and drying steps.

Further, in the case where an oxide layer is formed between the substrate and the diffusion preventing layer, the step of forming an oxide layer is performed before the step of forming the diffusion preventing layer. The step of forming the oxide layer is preferably carried out by subjecting the substrate before the diffusion preventing layer to a treatment such as an immersion treatment, an anodizing treatment, and a heating oxidation treatment.

Next, a catalyst using the copper base material of the present embodiment will be described. The catalyst of the present embodiment preferably includes the copper-based substrate of the present embodiment and a catalyst layer containing a catalyst material formed on the diffusion preventing layer of the copper-based substrate. Fig. 3 shows a catalyst 3 using the copper base material 1a shown in Fig. 1 as an example of the catalyst of the present embodiment.

As shown in FIG. 3, the catalyst 3 of the present embodiment has a catalyst layer 31 containing a catalyst material on the diffusion preventing layer 13 of the copper base material 1. In the case of the catalyst 3, the catalyst reaction mainly occurs on the surface of the catalyst layer 31 and in the vicinity of its surface. According to the catalyst 3, it is possible to effectively prevent the constituent components of the catalyst layer 31 from reacting or diffusing with the matrix 11 constituting the copper-based substrate 1, the constituent components of the oxide layer 12 which is arbitrarily formed, and the like. The reaction efficiency of the catalyst reaction by the catalyst layer 31 does not decrease over time.

The catalyst material constituting the catalyst layer 31 may, for example, be a cluster catalyst containing a metal cluster, or a nanoparticle. Among them, a catalyst material containing a metal cluster is particularly preferable from the viewpoint of high catalyst performance.

However, when the catalyst material contains a metal cluster, if a conventional substrate in which the diffusion preventing layer 13 of the present embodiment is not provided is used, the metal cluster contained in the catalyst layer 31 and the copper component constituting the substrate are used. Will spread and merge with each other, leading to the problem of not being able to fully utilize the unique performance of the cluster catalyst.

On the other hand, according to the copper-based substrate 1 provided with the diffusion preventing layer 13 in the present embodiment, even when the catalyst material contains a metal cluster, atomic diffusion can be effectively prevented, so that the performance of the cluster catalyst is not caused. Deterioration. In other words, the copper base material 1 of the present embodiment is particularly suitably used as a base material for a catalyst layer composed of a catalyst material containing a metal cluster.

In the present invention, the term "cluster" means a mixture of 2 to 100 metal atoms. Among them, it is preferably a collection of 10 to 40 metal atoms. Further, the metal contained in the metal cluster may be one or more selected from the group consisting of platinum (Pt), gold (Au), silver (Ag), copper (Cu), palladium (Pd), and iron (Fe). The metal material preferably contains copper, more preferably copper or a copper alloy. The catalyst material containing a metal cluster may contain metal particles other than the cluster in the catalyst material to the extent of 30% by mass.

Next, a method of producing a catalyst using the copper-based substrate of the present embodiment will be described. Hereinafter, a case where a catalyst layer composed of a catalyst material containing a metal cluster is formed will be described as an example, and an example of a method for producing a catalyst will be described. The method for producing a catalyst according to the present embodiment includes the step of forming a catalyst layer on the surface of the diffusion preventing layer of the copper-based substrate of the present embodiment. Further, it is also possible to further have a step of forming a surface protective layer on the surface of the catalyst layer as needed. The details will be described below.

First, the copper-based substrate of the above embodiment is prepared. Next, a catalyst layer composed of a catalyst material containing a metal cluster is formed on the diffusion preventing layer of the copper-based substrate. Such a catalyst layer can be formed by vapor-depositing a cluster catalyst on a diffusion preventing layer of a copper-based substrate. The method for forming the cluster catalyst is not particularly limited, and examples thereof include those described in the specification of International Publication No. 2014/192703.

Specifically, it can be formed by a magnetron sputtering method using a DC power source or the like. In this method, a device having a vacuum chamber, a cluster growth tank provided in the chamber, and a sputtering source (magnetron sputtering source) provided in the growth chamber of the cluster are used. Cluster catalyst. The cluster growth tank is surrounded by a liquid nitrogen jacket and is configured to flow a liquid nitrogen (N ₂ ) state in the liquid nitrogen jacket. Argon gas (Ar) is supplied to the sputtering source for plasma generation, and helium gas (He) is supplied to the cluster growth tank. The pulsed power is supplied from the sputtering source to supply the pulsed power, so that the target releases the sputtering particles such as neutral atoms and ions derived from the target into the helium gas. The metal atoms, metal ions, and the like generated by the sputtering sources are cooled, and the helium gas is used to agglomerate to form a cluster catalyst.

Such a catalyst of the invention is particularly useful as an electrode catalyst. In other words, the electrode catalyst of the present embodiment preferably includes the copper-based substrate of the present embodiment and a catalyst formed of a catalyst material containing a metal cluster formed on the diffusion preventing layer of the copper-based substrate. Floor. Such an electrode catalyst is suitably used as a cathode electrode as a carbon dioxide reduction device to be described later. In particular, when used as a cathode electrode, since the reaction overvoltage of cathode reduction can be reduced, the external bias voltage (external power) required can be lowered. That is, in the cathode reduction, the current efficiency of the reaction, the productivity, and the productivity can be improved.

In the electrolysis device of the present embodiment, it is preferable to use the copper base material of the present embodiment or the electrode catalyst of the present embodiment. The method of forming the device is not particularly limited, and it can be carried out by a known method. Examples of the electrolysis device include a reduction device for carbon dioxide, an electrolysis device for water, and the like.

In the following, an example of a case where the electrode catalyst using the copper-based substrate of the present embodiment is used as a cathode electrode for electrochemical reduction (electrolytic reduction, cathodic reduction) of carbon dioxide will be described.

Fig. 4 is a block diagram showing the construction of an electrolysis device 3 for performing electrochemical reduction of carbon dioxide. The electrolysis device 3 is mainly composed of a power source 31, an electrolytic cell 33, a gas recovery device 35, an electrolyte circulation device 37, a carbon dioxide supply unit 39, and the like.

The electrolytic cell 33 is a site where the target material is reduced, and is a portion containing the cathode electrode of the present embodiment, and carbon dioxide (including a case where the carbon dioxide ion is contained in the solution in addition to the dissolved carbon dioxide). Hereinafter, it is simply referred to as " Carbon dioxide, etc.") The site where the reduction takes place. Power is supplied from the power source 31 to the electrolytic cell 33.

The electrolyte circulation device 37 is a portion that circulates the cathode-side electrolyte to the cathode electrode of the electrolytic cell 33. The electrolyte circulation device 37 is, for example, a tank and a pump. The carbon dioxide supply unit 39 supplies carbon dioxide or the like so as to be dissolved in the electrolytic solution so as to be a predetermined carbon dioxide concentration, and can circulate the electrolyte between the electrolytic cell 33 and the electrolytic cell 33.

The gas recovery device 35 recovers a portion where the gas is reduced by the electrolytic cell 33 to generate gas. The gas recovery device 35 is capable of trapping a gas such as a hydrocarbon generated by the cathode electrode of the electrolytic cell 33. Further, in the gas recovery device 35, each gas may be separated depending on the type of gas.

The electrolysis device 3 has the following functions. As described above, the electrolytic cell 33 is given an electrolytic potential by the power source 31. The electrolyte solution (arrow A in the figure) is supplied to the cathode electrode of the electrolytic cell 33 by the electrolytic solution circulation device 37. At the cathode electrode of the electrolytic cell 33, carbon dioxide or the like in the supplied electrolyte is reduced. Carbon dioxide or the like is reduced to mainly form hydrocarbons such as ethane and ethylene.

The hydrocarbon gas generated by the cathode electrode is recovered by the gas recovery device 35 (arrow B in the figure). In the gas recovery device 35, the gas can be separated and stored as needed.

Since carbon dioxide or the like is reduced at the cathode electrode and consumed, the concentration of carbon dioxide or the like in the electrolyte is reduced. Carbon dioxide or the like which is reduced by the reduction reaction is often replenished so that the concentration is often kept within a predetermined range. Specifically, a part of the electrolytic solution (arrow C in the drawing) is recovered by the electrolytic solution circulation device 37, and a predetermined concentration of the electrolytic solution (arrow A in the figure) is often supplied. By the above, hydrocarbons can be generated in the electrolytic cell 33 under certain conditions.

Next, the electrolytic cell 33 will be described. FIG. 5 shows a configuration diagram of the electrolytic cell 33. The electrolytic cell 33 is mainly composed of a tank 316a of a cathode tank, a metal mesh 317, a cathode electrode 319, a cation exchange membrane 321, an anode electrode 320, and a tank 316b of an anode tank.

The electrolytes 315a and 315b are held in the grooves 316a and 316b, respectively. A hole for collecting a generated gas is formed on the upper portion of the groove 316a on the cathode electrode side, and is connected to a gas recovery device (not shown). That is, the gas generated by the cathode electrode is recovered from the pore. Further, a pipe or the like is connected to the groove 316a, and is connected to an electrolytic solution circulation device 37 (not shown). That is, the electrolytic solution 315a in the tank 316a can be circulated frequently by the electrolytic solution circulation device 37. Further, the electrolyte on the side of the groove 315b can also be circulated as needed.

The electrolytic solution 315a as the catholyte is preferably an electrolytic solution capable of dissolving a large amount of carbon dioxide or the like, and for example, an alkali solution such as a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, sodium carbonate, potassium carbonate, sodium hydrogencarbonate or potassium hydrogencarbonate can be used. A solution of monomethanolamine, methylamine, other liquid amines, or a mixture of such liquid amines and an aqueous electrolyte solution. Further, for example, acetonitrile, benzonitrile, dichloromethane, tetrahydrofuran, propylene carbonate, dimethylformamide, dimethyl hydrazine, methanol, ethanol or the like can be used. Further, in the case of water electrolysis for the purpose of hydrogen generation, pure water may be used as a suitable aqueous solution.

Further, as the electrolytic solution 315b as the anolyte, the above-described catholyte or appropriate pure water or an aqueous solution can be used.

The metal mesh 317 is connected to the negative electrode side of the power source 31 together with the reference electrode 318, and is a member for energizing the cathode electrode 319. As the metal mesh 317 such as a copper mesh or a stainless steel mesh, a reference electrode 318 may be a silver/silver chloride electrode or the like.

As the cation exchange membrane 321, for example, a well-known perfluorosulfonic acid (Nafion) system or the like can be used. Oxygen is used to move the cathode together with the generated hydrogen ions toward the cathode.

The anode electrode 320 is connected to the anode of the power source 31. As the anode electrode 320, an electrode having a small overvoltage due to oxygen can be used. For example, an electrode such as ruthenium oxide, platinum, or rhodium, or an oxide electrode, a stainless steel electrode, or a lead electrode can be coated on a substrate such as titanium or stainless steel.

Further, the anode electrode 320 can also be formed by a photocatalyst or a semiconductor electrode catalyst. That is, the electromotive force can be generated by irradiating light. In this manner, when the anode electrode is irradiated with light such as sunlight to generate an electromotive force, the electromotive force can be utilized as the electrolysis potential of the electrolytic cell 33.

At the cathode electrode 319, carbon dioxide or the like in the electrolytic solution is reduced. Carbon dioxide is dissolved in water, is present in the electrolyte in the state of dissolving carbon dioxide and hydrogen carbonate ions, and is supplied to the cathode electrode. When a cathode electrode is usually made of a material other than copper, a large amount of hydrogen and carbon monoxide tend to be formed, and almost no hydrocarbon is formed. On the other hand, when a cathode electrode is made of a copper-based material, hydrocarbons can be produced more efficiently.

The cathode electrode 319 of the present embodiment is constituted by the electrode catalyst of the present embodiment. That is, the cathode electrode 319 has a catalyst layer formed on the copper base material of the present embodiment. By using such a cathode electrode, carbon dioxide can be efficiently decomposed and reduced, and a useful hydrocarbon which can be used as energy can be generated with high energy efficiency.

The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, but encompasses all aspects of the present embodiment and the scope of the claims, and various changes can be made within the scope of the present invention. . [Examples]

Next, the embodiments and comparative examples will be described in order to clarify the effects of the present invention, but the present invention is not limited to the embodiments.

(Example 1) First, a base material was prepared by a TPC copper plate (manufactured by Furukawa Electric Co., Ltd., 10 mm × 10 mm × 0.1 mm). Next, pretreatment was carried out on the prepared substrate, which was subjected to cathode degreasing using an aqueous solution of a cleaning agent 160 (manufactured by Meltex Co., Ltd.), and washed with water, and then subjected to pickling using a dilute sulfuric acid aqueous solution (sulfuric acid concentration: 10% by mass). After neutralization, water washing is carried out. Next, a 2% by mass aqueous solution (hereinafter referred to as "2% by mass of BTA solution") of benzotriazole (manufactured by Seibu Chemical Industry Co., Ltd.) was prepared, and the pretreated substrate was placed in a 2% by mass BTA solution. The immersion treatment was carried out at 80 ° C for 2 minutes, and then dried at 80 ° C to obtain a copper-based substrate having a diffusion preventing layer on the surface of the substrate. Then, on the diffusion preventing layer of the obtained copper-based substrate, copper nanoparticle was used as a raw material to form copper nano-cluster ions by magnetron sputtering in accordance with the method described in the specification of International Publication No. 2014/192703, and copper was obtained. Cluster electrode catalyst.

(Example 2) In Example 2, instead of the 2% by mass BTA solution, a 0.5% by mass aqueous solution of benzotriazole (manufactured by Seongbuk Chemical Industry Co., Ltd.) (hereinafter referred to as "0.5 mass% BTA solution" was used instead. A copper-based substrate and an electrode catalyst using the same were produced in the same manner as in Example 1 except for the above.

(Example 3) In Example 3, except that the immersion treatment using a 0.5 mass% BTA solution was carried out by drying at 80 ° C, the application was repeated several times during the execution until the electric double layer capacitance countdown shown in Table 1 was obtained. A copper-based substrate and an electrode catalyst using the same were produced in the same manner as in Example 2 except for the above.

(Examples 4 to 6) In Examples 4 to 6, except that the immersion treatment using a 2% by mass BTA solution was carried out by drying at 80 ° C, the application was repeated several times during the execution until the electricity shown in Table 1 was obtained. A copper-based substrate and an electrode catalyst using the same were produced in the same manner as in Example 1 except that the double-layer capacitance was counted down.

(Example 7) In Example 7, a 2.5% by mass aqueous solution (hereinafter referred to as "2.5 mass%") of tolyltriazole (manufactured by Seongbuk Chemical Industry Co., Ltd.) was used instead of the 2% by mass BTA solution. The TTA solution was prepared in the same manner as in Example 1 except that the immersion treatment conditions using the 2.5% by mass TTA solution were 60 ° C for 2 minutes, and the subsequent drying conditions were changed to 60 ° C. A substrate, and an electrode catalyst using the same.

(Example 8) In the same manner as in Example 7, except that the 2.5% by mass TTA solution was used instead of the 2.5% by mass aqueous solution of imidazole (manufactured by Seongbuk Chemical Industry Co., Ltd.). A copper-based substrate and an electrode catalyst using the same are produced.

(Example 9) In Example 9, in place of the 2.5% by mass TTA solution, 1% by mass of benzotriazole (manufactured by Seongbuk Chemical Industry Co., Ltd.) and triazole (manufactured by Seibu Chemical Industry Co., Ltd.) were used instead. A copper-based substrate and an electrode catalyst using the same were prepared in the same manner as in Example 7 except for the 1.5% by mass aqueous solution.

(Comparative Example 1) In Comparative Example 1, an electrode was obtained in the same manner as in Example 1 except that the diffusion preventing layer was not formed, but the copper cluster was directly vapor-deposited on the surface of the pretreated substrate. catalyst.

(Comparative Example 2) In Comparative Example 2, in place of the 2% by mass BTA solution, a 5 mass% aqueous solution of an inorganic material ceria fine powder was prepared, and in the ceria solution, at 30 ° C, 1 The copper substrate was produced in the same manner as in Example 1 except that the pretreated substrate was subjected to an immersion treatment under a minute condition, and then dried at 80 ° C to form a diffusion preventing layer on the surface of the substrate. And the electrode catalyst using it.

(Example 10) In Example 10, a copper-based substrate was produced in the same manner as in Example 1, and the diffusion-preventing layer of the obtained copper-based substrate was described in the specification of International Publication No. 2014/192703. The Pd (Pd) particles are used as raw materials, and Pd nano-cluster ions are generated by magnetron sputtering to obtain a Pd cluster electrode catalyst.

[Evaluation] Using the copper base material and the electrode catalyst of the above-described examples and comparative examples, the following characteristics were evaluated. The evaluation conditions of each characteristic are as follows. The results are shown in Tables 1 and 2.

[1] Inversion of the electric double layer capacitor The surface of the copper base material of Examples 1 to 10 and Comparative Example 2 was measured before and after the formation of the diffusion preventing layer (before the formation of the diffusion preventing layer: the surface of the substrate after the pretreatment, and the diffusion prevention) After the layer was formed: the surface of the copper-based substrate, the electric double layer capacitance was calculated, and the reciprocal (1/C) was calculated. The measuring device was a direct-reading electric double-layer capacitance measuring device (impedance analyzer C instrument, manufactured by Hioki Electric Co., Ltd.), and the electrolytic solution was a 0.1 N potassium nitrate aqueous solution, and the conditions were in accordance with a step current of 50 μA/cm ² . Each sample was measured at two places (N=2), and an average value was obtained. Further, in Comparative Example 2, the electric double layer capacitance could not be detected due to the measurement limit.

[2] Reduction test of carbon dioxide The electrode catalysts of Examples 1 to 10 and Comparative Examples 1 and 2 were subjected to reduction test of carbon dioxide using a cathode electrode of a cathode reduction apparatus as carbon dioxide. The cathode reduction apparatus for carbon dioxide is roughly as shown above (Fig. 5). Further, a 50 mM aqueous solution of potassium hydrogencarbonate was used as the electrolytic solution, and 30 mL of each of the tanks 316a and 316b was used. The anode electrode 320 is a platinum electrode (manufactured by Tanaka Precious Metal Industries Co., Ltd.) which is coated with platinum on a titanium substrate. Electrolysis was carried out for 60 minutes under the conditions of a current of 2 mA and a voltage of 2.8V. Further, in the electrolysis, carbon dioxide gas was foamed at 10 mL/min by a supply pipe (in the direction of arrow A in the figure). Further, the gas generated by the cathode is collected by the analysis tube 323 (in the direction of the arrow B in the drawing), and analyzed by a gas chromatography layer analyzer. The column was SUPELCO CARBOXEN 1010 PLOT 30 m × 032 mm ID, and the detector was FID (manufactured by Sigma-Aldrich Co., Ltd.).

Further, the reaction of the cathode is focused on the formation of methane, ethylene, and ethane shown below. CO ₂ +8H ⁺ +8e ^- →CH ₄ +2H ₂ O CO ₂ +12H ⁺ +12e ^- →C ₂ H ₄ +4H ₂ O CO ₂ +14H ⁺ +14e ^- →C ₂ H ₆ +4H ₂ O as shown in Table 3. Further, in the present embodiment, when the methane gas concentration is 40 ppm or more, the ethylene gas concentration is 30 ppm or more, and the ethane gas concentration is 10 ppm or more, the pass level is evaluated as a pass level.

[Table 1]

[3] Electrolytic test of water The electrolysis test of water was carried out by replacing the electrolyte with ion-exchanged water by using the apparatus used for the reduction test of carbon dioxide described above. In addition, this test was carried out using each of Examples 1, 2, and 6 as a cathode electrode. Further, the conditions of electrolysis were set to a current of 2 mA, a voltage of 2.8 V, and 60 minutes. The results are shown in Table 2.

[Table 2]

As shown in Table 1, in the copper-based substrate of Examples 1 to 10 of the above-described embodiment, since a diffusion preventing layer made of an organic material is directly formed on a substrate made of copper, it is used as a catalyst electrode. In the case of the substrate, it was confirmed that an electrode catalyst capable of exhibiting good catalytic performance against cathodic reduction of carbon dioxide was obtained. Further, as shown in Table 2, using the catalyst electrode of the copper-based substrate (Examples 1, 2, and 6) of the present invention, even when electrolyzed with water, it was confirmed that the catalyst concentration exhibiting a hydrogen gas concentration of 600 ppm or more was observed. .

On the other hand, in the copper base materials of Comparative Examples 1 and 2, since the diffusion preventing layer made of an organic material is not provided on the substrate made of copper, the electrode catalyst using the same is compared with the present invention. In the electrode catalysts of Examples 1 to 10, it was confirmed that the catalyst activity at the time of cathode reduction of carbon dioxide was poor. The reason is that the copper-based base material of Comparative Examples 1 and 2 does not form a diffusion preventing layer of an organic material, and therefore copper constituting the matrix and the Cu cluster are fused, resulting in a decrease in activity as a cluster catalyst. Caused.

1‧‧‧ copper substrate

11‧‧‧ base

12‧‧‧Oxide layer

121‧‧‧ cuprous oxide layer

122‧‧‧ copper oxide layer

13‧‧‧Diffusion prevention layer

3‧‧‧Electrolytic device

31‧‧‧Power supply

33‧‧‧ Electrolytic cell (CO ₂ cathode reduction test device)

35‧‧‧ gas recovery unit

37‧‧‧Electrolyte circulation device

39‧‧‧Carbon Supply Department

315a, 315b‧‧‧ electrolyte

316a, 316b‧‧‧ slots

317‧‧‧Metal screen

318‧‧‧Reference electrode (silver/silver chloride)

319‧‧‧Cathode electrode

320‧‧‧Anode electrode

321‧‧‧Cation exchange membrane

323‧‧‧Analysis tube

325‧‧‧Supply tube

327‧‧‧ Sealing members

Fig. 1 is a schematic cross-sectional view showing an example of a copper-based substrate of the present invention. Fig. 2 is a schematic cross-sectional view showing another example of the copper-based substrate of the present invention. Fig. 3 is a schematic cross-sectional view showing an example of a catalyst using the copper-based substrate of the present invention. 4 is a schematic structural view of an electrolysis device. Fig. 5 is a schematic cross-sectional view showing the structure of an electrolytic cell (carbon dioxide reduction tank or water decomposition tank device) in the electrolysis device shown in Fig. 4.

Claims (8)

An electrode substrate comprising a substrate and a diffusion preventing layer, wherein the base system is formed of copper or a copper alloy; the diffusion preventing layer is formed on the surface of the substrate directly or via an oxide layer, and contains an organic material. . The electrode substrate according to the first aspect of the invention, wherein the copper substrate is a constituent substrate which is a catalyst for converting hydrogen into a catalyst containing a carbonaceous material by electrolysis of water to produce hydrogen or catalytic reduction of carbon dioxide. . The electrode substrate according to claim 1 or 2, wherein the organic material is an azole compound. The electrode substrate according to any one of claims 1 to 3, wherein the electric double layer capacitance has a reversed value of 0.3 to 5 cm ² /μF. An electrode substrate comprising: an electrode substrate according to any one of claims 1 to 4; and a catalyst layer formed on the diffusion preventing layer of the electrode substrate a catalyst material containing a metal cluster. The electrode catalyst according to claim 5, wherein the metal cluster is a cluster formed of copper or a copper alloy. An electrolysis device comprising the electrode substrate according to any one of claims 1 to 4, or the electrode catalyst according to claim 5 or 6. An electrolysis device comprising: a cathode comprising the copper-based substrate according to any one of claims 1 to 4; a catholyte; an anode; the anolyte; and an ion exchange membrane It is disposed between the cathode and the anode.