Manufacturing equipment

Abstract

To provide a manufacturing apparatus that can manufacture a carbon compound having C-C couplings with higher efficiency compared to that of conventional ones.SOLUTION: A manufacturing apparatus comprises a photoelectric conversion electrode, a counter electrode, and a gas supply unit. The photoelectric conversion electrode includes a first electrode layer, a photoelectric conversion unit, and a second electrode layer. The first electrode layer includes a surface electrode layer modified with sulfur atoms on a copper electrode. The surface electrode layer faces the counter electrode. The gas supply unit, which can supply gas that includes carbon dioxide to the surface electrode layer, is configured so that the carbon dioxide supplied onto the surface electrode layer is reduced to a carbon compound having C-C couplings when light is applied to the photoelectric conversion unit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an apparatus for producing a carbon compound having a C—C bond. [Background technology]

[0002] In recent years, efforts have been made to reduce emissions of carbon dioxide, a greenhouse gas, by generating carbon compounds from emitted carbon dioxide and turning it into a resource. For example, the electrochemical reaction cell 30 of Patent Document 1 includes a photoelectric conversion layer 32, an oxidation catalyst layer 33, an oxidation electrode layer 34, a first insulator 35, a reduction catalyst layer 36, a reduction electrode layer 37, a second insulator 38, wiring 39, an ion exchange membrane 40, a first electrolyte solution 41, and a second electrolyte solution 42. The electrochemical reaction cell 30 of Patent Document 1 has a surface of the photoelectric conversion layer 32 electrically connected to the oxidation catalyst layer 33 and a surface electrically connected to the reduction catalyst layer 36 via wiring 39, and when light is irradiated onto the photoelectric conversion layer 32, an electromotive force generated in the semiconductor layer within the photoelectric conversion layer 32 causes a reduction reaction of CO2 in the electrolyte in the reduction catalyst layer 36, producing carbon compounds such as carbon monoxide. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6870956 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the electrochemical reaction cell 30 of Patent Document 1, the photoelectric conversion layer 32 is located on the oxidation electrode layer 34 side, and carbon dioxide is reduced in the reduction catalyst layer 36 on the reduction electrode layer 37 via wiring 39. Therefore, a potential gradient is likely to be generated on the reduction electrode layer 37, and the carbonized compound produced varies depending on the location of the reduction electrode layer 37, resulting in a problem of low yield. Furthermore, when carbon dioxide, which is a C1 compound, is reduced in the electrochemical reaction cell 30 of Patent Document 1, most of the carbon compound becomes the C1 compound. That is, when a carbon compound having a C-C bond is produced using the electrochemical reaction cell 30 of Patent Document 1, it is necessary to produce the C1 compound first and then produce the carbon compound having a C-C bond in a separate process. Therefore, a method that can selectively produce a carbon compound having a C-C bond directly from carbon dioxide has been desired.

[0005] Therefore, an object of the present invention is to provide a production apparatus that can produce carbon compounds having CC bonds more efficiently than conventional methods. [Means for solving the problem]

[0006] One aspect of the present invention for solving the above-mentioned problems is a manufacturing apparatus comprising a photoelectric conversion electrode, a counter electrode, and a gas supply unit, wherein the photoelectric conversion electrode comprises a first electrode layer, a photoelectric conversion unit, and a second electrode layer, the first electrode layer comprising a surface electrode layer in which sulfur atoms are modified on a copper electrode, the surface electrode layer facing the counter electrode, the gas supply unit capable of supplying a gas containing carbon dioxide to the surface electrode layer, and when the photoelectric conversion unit is irradiated with light, the carbon dioxide supplied onto the surface electrode layer is reduced to a carbon compound having a C-C bond.

[0007] The term "CC bond" as used herein refers to a bond between two carbon atoms, and includes not only single bonds but also double bonds and triple bonds. The same applies hereinafter. The term "carbon compound" as used herein refers to a compound containing carbon, and includes not only organic compounds but also oxides such as carbon monoxide, carbonates, and carbides. The same applies hereinafter.

[0008] According to this aspect, the surface electrode layer of the first electrode layer is a copper electrode modified with sulfur atoms, so that a carbon compound having a C—C bond can be selectively produced. According to this aspect, carbon dioxide supplied onto the surface electrode layer formed on the surface of the photoelectric conversion electrode is reduced to carbon compounds with C-C bonds, so a potential gradient is unlikely to occur depending on the distance from the wiring, and carbon dioxide can be reduced to carbon compounds evenly. Therefore, carbon compounds can be produced more efficiently than before.

[0009] In a preferred aspect, the carbon compound is a C2 compound.

[0010] The term "C2 compound" used here refers to a compound with two carbon atoms.

[0011] According to this aspect, it is easy to produce from carbon dioxide.

[0012] In a preferred aspect, the carbon compound is at least one selected from the group consisting of ethane, ethylene, and ethanol.

[0013] This aspect makes it suitable for industrial and domestic use.

[0014] However, when a copper electrode is used as part of the surface electrode layer, copper may diffuse from the copper electrode side to the photoelectric conversion section side, and if the copper reaches the photoelectric conversion section, the photoelectric conversion section may be contaminated, resulting in a decrease in photoelectric conversion efficiency.

[0015] Therefore, in a preferred aspect, the first electrode layer includes an inhibition layer that inhibits copper from diffusing from the surface electrode layer side to the photoelectric conversion section side.

[0016] According to this aspect, the inhibition layer inhibits the diffusion of copper into the photoelectric conversion section, so that contamination of the photoelectric conversion section due to diffusion of copper from the copper electrode to the photoelectric conversion section can be suppressed.

[0017] In a preferred aspect, the device further comprises an auxiliary power supply unit that applies a voltage between the photoelectric conversion electrode and the counter electrode.

[0018] According to this aspect, the yield of the produced carbon compound can be adjusted by the voltage.

[0019] In a preferred aspect, the surface electrode layer is formed as a self-assembled monolayer.

[0020] According to this aspect, a CC bond is easily formed, and the yield of carbon compounds having a CC bond can be improved.

[0021] In a preferred aspect, the self-assembled monolayer is a methanethiol layer containing the sulfur atom.

[0022] According to this aspect, the yield of carbon compounds having a C—C bond can be further improved.

[0023] In a preferred aspect, the photoelectric conversion electrode and the counter electrode are partially immersed in the electrolyte, the first electrode layer is exposed to the electrolyte, and the second electrode layer is not exposed to the electrolyte.

[0024] According to this aspect, it is possible to prevent a short circuit between the first electrode layer and the second electrode layer via the electrolyte. [Effects of the Invention]

[0025] According to the production apparatus of the present invention, carbon compounds having C—C bonds can be produced more efficiently than conventional methods. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a cross-sectional view conceptually showing a manufacturing apparatus according to a first embodiment of the present invention. [Figure 2] 2A and 2B are explanatory views of the photoelectric conversion electrode of FIG. 1, where (a) is a view from the first electrode layer side, and (b) is a view from the second electrode layer side. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, embodiments of the present invention will be described in detail.

[0028] As shown in FIG. 1, the manufacturing apparatus 1 of the first embodiment of the present invention includes a reaction tank 2, a photoelectric conversion electrode 3, a counter electrode 5, an ion exchange unit 6, electrolytes 7a and 7b, a gas supply unit 8, electrolyte supply units 10a and 10b, gas exhaust units 11a and 11b, electrolyte exhaust units 12a and 12b, and an auxiliary power supply unit 13.

[0029] The reaction tank 2 includes a tank body 20 and a window 21, and the window 21 can be opened and closed relative to the tank body 20. In other words, when the window portion 21 of the reaction vessel 2 is in an open state, the photoelectric conversion electrode 3 is exposed to the outside, allowing light to enter the photoelectric conversion electrode 3, and when the window portion 21 is in a closed state, the photoelectric conversion electrode 3 is covered by the window portion 21, preventing light from entering the photoelectric conversion electrode 3 from the outside.

[0030] The photoelectric conversion electrode 3 is a solar cell electrode including a first electrode layer 30, a photoelectric conversion section 31, and a second electrode layer 32, as shown in FIG. The photoelectric conversion electrode 3 is capable of generating an electromotive force (potential difference) between the first electrode layer 30 and the second electrode layer 32 when the photoelectric conversion section 31 receives light from the second electrode layer 32 side. The first electrode layer 30 has an inhibition layer 35 and a surface electrode layer 36 in this order from the photoelectric conversion section 31 side.

[0031] The inhibition layer 35 is a conductive layer having electrical conductivity, and is a diffusion inhibition layer that inhibits the diffusion of the copper electrode 38 of the surface electrode layer 36 toward the photoelectric conversion section 31 side. The inhibition layer 35 is interposed between the photoelectric conversion section 31 and the surface electrode layer 36, and covers the entire surface of the photoelectric conversion section 31 on the first electrode layer 30 side. The material of the inhibition layer 35 is not particularly limited as long as it is conductive and can inhibit the diffusion of the copper electrode 38 toward the photoelectric conversion section 31. For example, the inhibition layer 35 can be made of a metal or alloy such as silver or aluminum, or a transparent conductive oxide such as indium tin oxide (ITO).

[0032] The surface electrode layer 36 is configured by laminating a self-assembled monolayer 39 on a copper electrode 38 . The copper electrode 38 is a plated layer formed by plating, and functions as a catalyst. The self-assembled monolayer 39 is a layer modified with sulfur atoms as heteroatoms, and specifically, is a methanethiol layer.

[0033] The photoelectric conversion section 31 has a semiconductor layer of one conductivity type and a semiconductor layer of the opposite conductivity type, and is capable of converting light energy into electrical energy when irradiated with light. "One conductivity type" refers to one of the p-type and n-type conductivity types, and "opposite conductivity type" refers to the other of the p-type and n-type conductivity types that is different from the one conductivity type. The photoelectric conversion unit 31 of this embodiment has a p-type silicon layer formed on one main surface of an n-type silicon substrate, and an n-type silicon layer formed on the other main surface of the n-type silicon substrate. Note that an i-type silicon layer may be interposed between the n-type silicon substrate and the p-type silicon layer, or between the n-type silicon substrate and the n-type silicon layer. Also, a p-type silicon substrate may be used instead of the n-type silicon substrate.

[0034] The second electrode layer 32 is an electrode layer on the light-receiving side, and has a transparent electrode layer 40 and a light-transmitting electrode layer 41 in this order from the photoelectric conversion section 31 side, as shown in FIG. The transparent electrode layer 40 is a transparent conductive layer that is translucent and conductive, and may be made of a transparent conductive oxide such as indium tin oxide (ITO). The light-transmitting electrode layer 41 is a layer that transmits light in the thickness direction, and is specifically a metal electrode layer formed in a mesh pattern as shown in FIG. 2(b). In the second electrode layer 32, the light-transmitting electrode layer 41 does not cover the entire surface of the transparent electrode layer 40, and the second electrode layer 32 includes a plurality of light-transmitting portions 42 that can transmit light in the thickness direction. That is, the light-transmitting portion 42 is an opening portion where the light-transmitting electrode layer 41 is not provided, and where the transparent electrode layer 40 is exposed.

[0035] As shown in FIG. 1, the counter electrode 5 is an electrode that forms a pair with the photoelectric conversion electrode 3 and faces the photoelectric conversion electrode 3 with the ion exchange unit 6 interposed therebetween. The counter electrode 5 is resistant to corrosion by the second electrolytic solution 7b and functions as a catalyst. The counter electrode 5 may be, for example, a conductive plate carrying a metal catalyst such as platinum or an alloy catalyst, or a metal plate such as platinum or an alloy plate. The shape of the counter electrode 5 is not particularly limited as long as it can function as a counter electrode for the photoelectric conversion electrode 3. The counter electrode 5 may be in the form of a plate or a mesh.

[0036] The ion exchange section 6 is a cation exchange membrane or an anion exchange membrane, and is a portion that allows the movement of one of cations and anions and blocks the movement of the other ion. The ion exchange section 6 of this embodiment is a proton conductive membrane having proton conductivity, and for example, Nafion (registered trademark) can be used.

[0037] The electrolytic solutions 7a and 7b are conductive liquids, and for example, water, an alkaline aqueous solution, an acidic aqueous solution, or the like can be used, and an electrolyte may be added as needed. The electrolytic solutions 7a and 7b may be the same or different.

[0038] The gas supply unit 8 is a part that supplies carbon dioxide toward the first electrode layer 30 of the photoelectric conversion electrode 3. The gas supply unit 8 is capable of adjusting the amount of carbon dioxide supplied in accordance with the rate of carbon compound production.

[0039] The electrolytic solution supply units 10a and 10b are parts that supply the electrolytic solutions 7a and 7b into the reaction vessel 2 from the outside. The gas exhaust sections 11a and 11b are sections that exhaust gases inside the reaction vessel 2 to the outside. The first gas discharge part 11a is a part that discharges gaseous carbon compounds generated on the photoelectric conversion electrode 3 to the outside of the reaction vessel 2. The second gas discharge part 11b is a part that discharges the gaseous by-product gas generated on the counter electrode 5 to the outside of the reaction vessel 2.

[0040] The electrolytic solution discharge portions 12a and 12b are portions for discharging the electrolytic solutions 7a and 7b in the reaction vessel 2 to the outside. The first electrolytic solution discharge part 12a is a part that discharges the liquid carbon compound produced on the photoelectric conversion electrode 3 and the unreacted first electrolytic solution 7a to the outside of the reaction vessel 2. The second electrolytic solution discharge part 12b is a part that discharges the hydrogen peroxide produced at the counter electrode 5 and the unreacted second electrolytic solution 7b to the outside of the reaction vessel 2. The auxiliary power supply unit 13 is a unit that applies a voltage between the photoelectric conversion electrode 3 and the counter electrode 5, and the power source of the auxiliary power supply unit 13 can be renewable energy such as a solar cell or commercial power.

[0041] Next, the positional relationship between the components of the manufacturing apparatus 1 of this embodiment will be described.

[0042] In the manufacturing apparatus 1, as shown in FIG. 1, the first electrode layer 30 of the photoelectric conversion electrode 3 and the counter electrode 5 face each other with a gap therebetween, and an ion exchange unit 6 is located between the photoelectric conversion electrode 3 and the counter electrode 5. In the manufacturing apparatus 1, a first electrolytic solution 7a is filled between the photoelectric conversion electrode 3 and the ion exchange unit 6, and a second electrolytic solution 7b is filled between the ion exchange unit 6 and the counter electrode 5. That is, in the manufacturing apparatus 1, the photoelectric conversion electrode 3 is immersed in the first electrolytic solution 7a, and the counter electrode 5 is immersed in the second electrolytic solution 7b. The photoelectric conversion electrode 3 has a main surface on the first electrode layer 30 side in contact with the first electrolytic solution 7a, and a main surface on the second electrode layer 32 side facing the window portion 21. In the photoelectric conversion electrode 3, the first electrode layer 30 is exposed to the first electrolytic solution 7a, and the second electrode layer 32 is not exposed to the first electrolytic solution 7a. At least the surface of the counter electrode 5 facing the photoelectric conversion electrode 3 is exposed to the second electrolytic solution 7b. When the window portion 21 is in an open state, it is possible for light to enter the photoelectric conversion portion 31 from the outside through the second electrode layer 32, and when it is in a closed state, it is possible to block light from reaching the photoelectric conversion portion 31.

[0043] As shown in FIG. 1 , the manufacturing apparatus 1 is provided with a gas supply unit 8 and electrolyte solution supply units 10a, 10b at the bottom of the reaction vessel 2, and with gas exhaust units 11a, 11b at the top of the reaction vessel 2, specifically at the top of the reaction vessel 2. The manufacturing apparatus 1 is also provided with electrolyte solution exhaust units 12a, 12b on the side of the reaction vessel 2 on the top side of the reaction vessel 2. Therefore, in the manufacturing apparatus 1, when the water levels of the electrolyte solutions 7a, 7b rise above the electrolyte solution exhaust units 12a, 12b due to the supply of electrolyte solutions 7a, 7b from the electrolyte solution supply units 10a, 10b into the reaction vessel 2 or the occurrence of reactions on the photoelectric conversion electrode 3 or the counter electrode 5, the electrolyte solutions 7a, 7b are discharged from the electrolyte solution exhaust units 12a, 12b to the outside.

[0044] Next, a method for producing a carbon compound having a carbon-carbon bond using the production apparatus 1 of this embodiment will be described. In this embodiment, a case will be described in which a carbon compound is produced on the surface electrode layer 36 of the photoelectric conversion electrode 3, and hydrogen peroxide is produced on the counter electrode 5.

[0045] First, carbon dioxide is supplied from the gas supply unit 8 onto the surface electrode layer 36 of the first electrode layer 30, and the window unit 21 is opened to introduce light into the photoelectric conversion unit 31 from the second electrode layer 32 side of the photoelectric conversion electrode 3.

[0046] At this time, the photoelectric conversion section 31 receives light and generates an electromotive force, generating a voltage between the surface electrode layer 36 of the photoelectric conversion electrode 3 and the counter electrode 5 .

[0047] Then, as necessary, a voltage is applied between the photoelectric conversion electrode 3 and the counter electrode 5 by the auxiliary power supply unit 13. Specifically, the auxiliary power supply unit 13 applies a voltage that compensates for the insufficient electromotive force generated by the photoelectric conversion electrode 3 so that the voltage on the surface electrode layer 36 of the photoelectric conversion electrode 3 becomes equal to or lower than −1.4 V (vs. Ag / AgCl) and the voltage on the counter electrode 5 becomes equal to or higher than the potential of the hydrogen peroxide production reaction of water. As a result, a carbon compound is produced on the surface electrode layer 36 of the photoelectric conversion electrode 3, and hydrogen peroxide is produced on the counter electrode 5.

[0048] At this time, on the surface electrode layer 36 of the photoelectric conversion electrode 3, carbon dioxide is reduced to carbon monoxide, and the carbon monoxides further dimerize to produce a C2 compound, which is a carbon compound having a CC bond. Examples of C2 compounds produced include ethane, ethylene, and ethanol.

[0049] If the carbon compound produced on the photoelectric conversion electrode 3 is in liquid form, it is discharged to the outside together with the first electrolytic solution 7a from the first electrolytic solution discharge section 12a, and if it is in gaseous form, it is discharged to the outside together with unreacted carbon dioxide from the first gas discharge section 11a and recovered. The hydrogen peroxide produced on the counter electrode 5 is discharged together with the second electrolytic solution 7b from the second electrolytic solution discharge part 12b to an external tank.

[0050] According to the manufacturing apparatus 1 of this embodiment, the surface electrode layer 36 of the first electrode layer 30 is modified with sulfur atoms as a self-assembled monolayer 39 on the copper electrode 38, so that carbon compounds having C-C bonds can be selectively produced. According to the manufacturing apparatus 1 of this embodiment, carbon dioxide supplied onto the surface electrode layer 36 formed on the surface of the photoelectric conversion electrode 3 is reduced to a carbon compound having a C-C bond, so that carbon dioxide can be reduced to a carbon compound evenly. Therefore, carbon compounds can be manufactured more efficiently than conventional methods.

[0051] According to the production apparatus 1 of this embodiment, C2 carbon compounds such as ethane, ethylene, and ethanol are produced as carbon compounds, making it easy to use the carbon compounds for industrial and domestic purposes.

[0052] According to the manufacturing apparatus 1 of this embodiment, the first electrode layer 30 of the photoelectric conversion electrode 3 is provided with an inhibition layer 35 that inhibits the diffusion of copper from the surface electrode layer 36 side to the photoelectric conversion section 31 side, so that even when a copper electrode 38 is used, which is a concern for contaminating the photoelectric conversion section 31, contamination of the photoelectric conversion section 31 by copper can be suppressed.

[0053] The manufacturing apparatus 1 of this embodiment includes an auxiliary power supply unit 13 that applies a voltage between the photoelectric conversion electrode 3 and the counter electrode 5, so that the carbon compounds generated on the photoelectric conversion electrode 3 and the products generated on the counter electrode 5 can be adjusted by the voltage.

[0054] According to the manufacturing apparatus 1 of this embodiment, the self-assembled monolayer 39 is formed on the copper electrode 38 of the surface electrode layer 36, which assists the reduction reaction at the copper electrode 38, making it easier to form C-C bonds, and improving the yield of carbon compounds having C-C bonds.

[0055] According to the manufacturing apparatus 1 of this embodiment, the photoelectric conversion electrode 3 and the counter electrode 5 are partially immersed in the electrolyte solutions 7a and 7b, the first electrode layer 30 is exposed to the electrolyte solution 7a, and the second electrode layer 32 is not exposed to the electrolyte solution 7a, so that a short circuit between the first electrode layer 30 and the second electrode layer 32 via the electrolyte solution 7a can be prevented.

[0056] In the above-described embodiment, hydrogen peroxide is generated by oxidizing water in the electrolyte solution 7b on the counter electrode 5, but the present invention is not limited to this. The product on the counter electrode 5 is not particularly limited as long as it is obtained by an oxidation reaction. For example, oxygen may be generated on the counter electrode 5 by adjusting the voltage.

[0057] In the above-described embodiment, an auxiliary power supply unit 13 is provided to apply a voltage between the photoelectric conversion electrode 3 and the counter electrode 5, but the present invention is not limited to this. If the electromotive force generated by irradiating the photoelectric conversion electrode 3 with light is a voltage sufficient for the oxidation-reduction reaction to proceed, the auxiliary power supply unit 13 does not need to be provided.

[0058] In the above-described embodiment, the photoelectric conversion electrode 3 is exposed to the outside when the window 21 is opened, but the present invention is not limited to this. A light-transmitting plate may be interposed between the window 21 and the photoelectric conversion electrode 3, and when the window 21 is opened, the light-transmitting plate may be exposed to the outside, but the photoelectric conversion electrode 3 may not be exposed to the outside.

[0059] In the above embodiment, the copper electrode 38 is formed by plating, but the present invention is not limited to this. It may be formed by a PVD method such as sputtering, or by a printing method using a conductive paste or the like.

[0060] In the above-described embodiments, each component can be freely substituted or added between the respective embodiments as long as it falls within the technical scope of the present invention. [Explanation of symbols]

[0061] 1 Manufacturing equipment 3 Photoelectric conversion electrode 5. Opposite 7a 1st electrolyte 7b Second electrolyte 8 Gas supply section 13 Auxiliary power supply section 30 1st electrode layer 31 Photoelectric conversion unit 32 Second electrode layer 35 Inhibitory layer 36 Surface electrode layer 38 copper electrode 39 Self-assembled monolayer

Claims

1. a photoelectric conversion electrode, a counter electrode, and a gas supply unit; the photoelectric conversion electrode has a first electrode layer, a photoelectric conversion unit, and a second electrode layer; the first electrode layer has a surface electrode layer modified with sulfur atoms on a copper electrode, the surface electrode layer faces the counter electrode, the surface electrode layer has a self-assembled monolayer formed thereon; the self-assembled monolayer is a methanethiol layer containing the sulfur atom, the gas supply unit is capable of supplying a gas containing carbon dioxide to the surface electrode layer; When the photoelectric conversion unit is irradiated with light, the manufacturing apparatus reduces carbon dioxide supplied onto the surface electrode layer to a carbon compound having a C—C bond.

2. The manufacturing apparatus according to claim 1 , wherein the carbon compound is a C2 compound.

3. 3. The manufacturing apparatus according to claim 1, wherein the carbon compound is at least one selected from the group consisting of ethane, ethylene, and ethanol.

4. 4. The manufacturing apparatus according to claim 1, wherein the first electrode layer includes an inhibition layer that inhibits copper from diffusing from the surface electrode layer side to the photoelectric conversion portion side.

5. 5. The manufacturing apparatus according to claim 1, further comprising an auxiliary power supply unit that applies a voltage between the photoelectric conversion electrode and the counter electrode.

6. the photoelectric conversion electrode and the counter electrode are partially immersed in an electrolyte; the first electrode layer is exposed to the electrolyte; The manufacturing apparatus according to any one of claims 1 to 5, wherein the second electrode layer is not exposed to the electrolyte solution.

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