Carbon dioxide reduction device

Abstract

Provided is a practical device for reducing the amount of carbon dioxide within a space.　This carbon dioxide reduction device comprises a container 10 in which an aqueous solution 50 of sodium chloride is stored at the bottom thereof. The container 10 has an intake port 11 and an exhaust port 13. The container 10 includes therein a needle-shaped electrode 21, a planar electrode 22, and a cylindrical electrode 23. 8000-V pulsed voltage is applied between the needle-shaped electrode 21 and both the planar electrode 22 and cylindrical electrode 23 so that the needle-shaped electrode 21 becomes negative. The aqueous solution 50 taken up from the bottom of the container 10 spreads out in the form of a layer on the planar electrode 22 and is exposed to corona discharge.

Description

[Technical Field]

[0001] The present invention relates to a technique for reducing carbon dioxide (CO2) in a partitioned space such as a room in a house or the interior of a vehicle such as an automobile. [Background technology]

[0002] It is well known that it is desirable to reduce the amount of carbon dioxide in a given space, or to lower the carbon dioxide concentration. In this case, the space refers to, for example, a space separated from the outside in real estate (such as an office in an office building or a classroom in a school), or an indoor space separated from the outside, such as an automobile, airplane, or ship. If the carbon dioxide concentration in a room increases, it can affect the physical condition of people inside and reduce the efficiency of work or study. Taking such factors into consideration, for example, the Building Environmental Sanitation Management Standards established by the Ministry of Health, Labor and Welfare of Japan also set standards for desirable carbon dioxide concentrations in indoor environments. Summary of the Invention [Problem to be solved by the invention]

[0003] Ventilation is a commonly used method for reducing carbon dioxide concentrations, but ventilation reduces the efficiency of heating and cooling within the space, posing challenges in terms of energy efficiency and cost. Furthermore, if ventilation is performed automatically, such problems do not arise, but if it is performed manually, it is often the case that ventilation is not performed at all because the person forgets to ventilate.

[0004] Although there are theoretically various technologies for reducing carbon dioxide or lowering the carbon dioxide concentration in a space, the current situation is that there are no practical ones, or at least no products for such purposes.

[0005] An object of the present invention is to provide a practical technique for reducing carbon dioxide in a space. [Means for solving the problem]

[0006] The present invention, which aims to solve the above-mentioned problems, was made in the following manner. The applicant of the present application has filed a patent application for an invention relating to a device that gasifies an aqueous solution containing sodium ions and releases the ions, and has already been granted a patent (Patent Document 1: Japanese Patent Publication No. 5819560). The applicant of the present application has also been manufacturing and selling an ion release device that is an embodiment of the invention.

[0007] This ion emission device is generally configured as follows. The ion emitting device includes a container having an aqueous solution containing sodium ions stored at its bottom, and having an air inlet that is an opening for introducing air into the container and an exhaust port for discharging air from the container. Inside the container, there are provided a first cathode that is an electrode provided between the air inlet and the bottom of the container, and a first anode that is an electrode paired with the first cathode and located below the first cathode, to which a positive voltage relative to the first cathode is applied. The ion emission device includes a power supply, and the power supply applies a constant potential voltage between the first cathode and the first anode that is high enough to generate a corona discharge therebetween. When a voltage large enough to generate a corona discharge is applied between the pair of first cathode and first anode, an ionic wind is generated in the air entering the container through the air intake. The direction of the ionic wind is from the first cathode to the first anode, so the ionic wind flows downward within the container. This causes the ionic wind and air to collide with the aqueous solution stored at the bottom of the container. This causes part of the aqueous solution to evaporate, and many fine, negatively charged droplets of aqueous solution are generated from the aqueous solution. These negatively charged droplets are then expelled from the exhaust port of the container and released into the space within a specified room, for example. Space sterilization is achieved by releasing negatively charged aqueous solution particles into a room or other space. In other words, the ion emitting device in the patent application previously filed by the applicant of the present application was a device intended for spatial sterilization.

[0008] Incidentally, the detailed mechanism by which negatively charged fine particles of aqueous solution are generated from an aqueous solution in the ion emission device described in Patent Document 1 was not well understood at least at the time of filing of Patent Document 1. Furthermore, it was not clear what the negatively charged fine particles of aqueous solution released from the ion emission device were, for example, whether there was only one type of particle or whether there were multiple types of particles with different properties. Therefore, in order to further improve the ion emission device, the applicant of the present application conducted an analysis of what phenomena or chemical reactions were occurring inside the ion emission device, and what the fine particles emitted from the ion emission device were as a result. As a result, it was confirmed that the substances emitted from the ion emitter contained trace amounts of sodium carbonate (NaCO3) and sodium bicarbonate (NaHCO3).

[0009] At this point, the applicant realized something: sodium carbonate and sodium bicarbonate both contain carbon (C). However, since no carbon-containing substances are present in the aqueous solution of the ion emitter, it is thought that this carbon comes from substances contained in the air taken into the ion emitter. However, the carbon present in the air is essentially only carbon in carbon dioxide, except for an almost negligible amount of carbon monoxide. This means that the above-mentioned ion emission device fixes the carbon in carbon dioxide into sodium carbonate and sodium bicarbonate, or thereby reduces carbon dioxide, during at least part of the process of releasing negatively charged aqueous solution droplets into space. In other words, it was found that the above-mentioned ion emitting device also functions as a carbon dioxide reduction device.

[0010] However, when a conventional ion emitting device is operated, the substances emitted include sodium carbonate and sodium bicarbonate, but in extremely small amounts, which means that the amount of carbon dioxide reduced is also small. Therefore, if a conventional ion emitting device is used as a carbon dioxide reduction device for the purpose of reducing carbon dioxide in the air, the efficiency is too low and it is not suitable for practical use. Therefore, the inventors of the present application further analyzed and researched the ion emission device, and came up with the idea that, in conventional ion emission devices, when a downward ionic wind generated by a corona discharge between the first cathode and the first anode is caused to collide with an aqueous solution, a reaction (hereinafter sometimes referred to as the "specific reaction") is likely to occur in which sodium carbonate and sodium bicarbonate are produced using carbon contained in carbon dioxide in the air. However, if the aqueous solution can be placed inside the corona discharge, the specific reaction may be able to occur more effectively. They then prototyped an ion emission device that can place an aqueous solution in a corona discharge and tested its effectiveness in reducing carbon dioxide. Although the detailed mechanism is still unknown, the effectiveness of carbon dioxide reduction was actually significantly improved. The present invention was made in this way.

[0011] The present invention, which has been made in the circumstances described above, is as follows. The present invention is a carbon dioxide reduction device comprising: an aqueous solution tank for storing an aqueous solution containing sodium ions; a container having an air intake port which is an opening for introducing air into the container and an exhaust port which is an opening for discharging air from the container; a first cathode which is an electrode provided within the container; a first anode which is an electrode provided within the container and is paired with the first cathode and has an electrode surface that extends in a planar manner facing the first cathode, to which a positive voltage relative to the first cathode is applied; a power supply device that applies a voltage of a potential that generates a corona discharge between the first cathode and the first anode; and a supply member that supplies the aqueous solution from the aqueous solution tank to the electrode surface, wherein the aqueous solution that has spread in a film form on the electrode surface is exposed to a corona discharge generated between the first cathode and the first anode by the application of voltage from the power supply device. This carbon dioxide reduction device includes a container. The container is airtight except for an air inlet and an exhaust port. The carbon dioxide reduction device includes an aqueous solution tank for storing an aqueous solution containing sodium ions. The aqueous solution tank may be located either inside or outside the container. The container also includes an air inlet, which is an opening for introducing air into the container, and an exhaust port, which is an opening for discharging air from the container. A first cathode and a first anode, to which a positive voltage is applied relative to the first cathode, are provided within the container. The first anode has a planar electrode surface facing the first cathode. The carbon dioxide reduction device includes a supply member that supplies the aqueous solution from the aqueous solution tank to the electrode surface. The aqueous solution transported by the supply member forms a film on at least a predetermined area of ​​the electrode surface. The carbon dioxide reduction device also includes a power supply that applies a voltage at a potential that generates a corona discharge between the first cathode and the first anode. The power supply applies a voltage between the first cathode and the first anode, generating a corona discharge between them. The ionic wind generated by the corona discharge flows from the first cathode to the first anode, causing both the ionic wind and the air accelerated by the ionic wind to collide with the aqueous solution on the electrode surface of the first anode. This causes a specific reaction, in which carbon contained in carbon dioxide in the air is used to produce sodium carbonate and sodium bicarbonate. As described above, the first anode has a planar electrode surface facing the first cathode. Therefore, a corona discharge occurs between the electrode surface of the first anode and the first cathode. As a result, in the carbon dioxide reduction device of the present application, the aqueous solution located on the electrode surface of the first anode is located in a space where a corona discharge occurs. In other words, in the carbon dioxide reduction device of the present application, the aqueous solution on the electrode surface of the first anode is exposed to the corona discharge generated between the first cathode and the first anode. It may be that exposing the aqueous solution to a corona discharge causes further specific reactions, or that exposing the aqueous solution to a corona discharge further promotes the specific reactions described above that occur when ionic wind collides with the aqueous solution. In any case, exposing the aqueous solution to a corona discharge makes it possible to cause more specific reactions than before. Although the detailed mechanism is unclear, the applicant speculates that the following phenomenon occurs when the aqueous solution is exposed to a corona discharge, and that this promotes the specific reactions. When an aqueous solution is exposed to a corona discharge, the water (HO) in the solution is converted into hydrogen ions (H + ) and hydroxide ions (OH - ) in the aqueous solution. + ), the water in the aqueous solution ionizes, generating a large amount of hydroxide ions, which accelerates the following two chemical reactions. This is presumably the reason why specific reactions are accelerated and carbon dioxide emissions are significantly reduced. 2Na + +2OH - +CO2→Na2CO3+H2O Na + +OH - +CO2→NaHCO3 In addition, this carbon dioxide reduction device also causes a reaction similar to that of the ion emission device described in Patent Document 1. In other words, this carbon dioxide reduction device causes a reaction in which ion wind is generated by corona discharge and a reaction in which the ion wind collides with an aqueous solution together with air accelerated by the ion wind. Therefore, the carbon dioxide reduction device according to the present application basically maintains the spatial sterilization effect of the ion emission device. In that sense, the carbon dioxide reduction device according to the present application has the characteristics of a spatial sterilization device and can also be said to be a spatial sterilization device.

[0012] As described above, the first cathode and the first anode are capable of generating a corona discharge between them. The first anode has a planar electrode surface facing the first cathode, which is intended to form a film-like spread of the aqueous solution on the electrode surface. The spread of the aqueous solution is exposed to a corona discharge, which promotes the specific reaction. Furthermore, since the electrode surface of the first anode has a planar spread, it is expected that the discharge from the first cathode to the first anode will be directed toward various locations on the electrode surface. This likely enhances the effect of promoting the specific reaction, since the specific reaction is promoted at various locations in the aqueous solution spread on the planar electrode surface. In contrast, the first cathode does not need to have an electrode surface, and its shape has a certain degree of freedom. For example, the first cathode may be configured as a needle-like electrode protruding toward the electrode surface. When the first cathode is a needle-like electrode, the electrode surface of the first anode may be concave toward the first cathode (e.g., the first cathode is a needle-like electrode). This allows discharge from the first cathode to the first anode to occur relatively evenly at various positions on the electrode surface of the first anode. This is expected to promote a specific reaction. For example, the electrode surface may have a circular flat portion in the center and its periphery gently rising from the flat portion, like the inner surface of a pot. The needle-like electrode may be provided in a plurality of pieces, so that corona discharges are generated between the electrode surface and the tips of the plurality of needle-like electrodes, up to the number of which is equal to the number of the needle-like electrodes, thereby further promoting the specific reaction.

[0013] There is no particular limitation on the relative positional relationship between the first cathode and the first anode. For example, the electrode surface may be located below the first cathode, so that the corona discharge occurs in the vertical direction. In this case, the electrode surface may be horizontal, for example. The vertical direction does not necessarily mean the vertical direction. This is especially true when there are multiple first cathodes that are needle-shaped electrodes. The electrode surface may be located to the side of the first cathode, so that the corona discharge occurs in the horizontal direction. In this case, the electrode surface may be, for example, vertical. The horizontal direction does not necessarily mean the horizontal direction. This is especially true when there are multiple first cathodes that are needle-shaped electrodes.

[0014] There are no particular limitations on the configuration or location of the aqueous solution tank, as long as it can store the aqueous solution therein. For example, regardless of the positional relationship between the first cathode and the first anode, a predetermined area below the first cathode and the first anode at the bottom of the container may be used as the aqueous solution tank. In this way, the area near the bottom of the container can be used as the aqueous solution tank, which may be useful in making the volume of the carbon dioxide reduction device more compact and also leads to a reduction in the number of parts. Furthermore, regardless of the relative positions of the first cathode and the first anode, the aqueous solution tank may be provided outside the container, which makes it easier to increase the volume of the aqueous solution tank.

[0015] As described above, the aqueous solution in the aqueous solution tank is supplied from the aqueous solution tank to the surface of the electrode face of the first anode by a supply member. The supply member may be composed of, for example, a tube having one end immersed in the aqueous solution tank and the other end extending to or near the electrode face, and a pump that sends the aqueous solution from the aqueous solution tank to the surface of the electrode face through the tube. On the other hand, the supply member may have a water-absorbing member made of a water-absorbing material, one end of which is immersed in the aqueous solution tank and the other end of which extends to or near the electrode surface, so that the aqueous solution in the aqueous solution tank absorbed by the water-absorbing member is supplied to the surface of the electrode surface. By using a supply member having a water-absorbing member, it is possible to omit components that require external energy input for operation, such as a pump, and it also leads to cost reduction and malfunction reduction. When a water-absorbing member is used, the first anode may be plate-shaped. In this case, the other end of the water-absorbing member may extend to the back side of the electrode surface of the first anode. When the water-absorbing member extends to the back side of the electrode surface, the first anode may have a hole for passing the aqueous solution supplied from the water-absorbing member. In this case, the hole may be one, or may be multiple or many. If there are many holes, for example, evenly distributed over the entire plate-shaped first anode, it becomes easier to evenly supply the aqueous solution over the entire electrode surface above the first anode, and it becomes easier to evenly spread the aqueous solution over the entire electrode surface. When the first anode has many holes, the first anode may be made of a metal mesh material. For example, if the first anode is made of a mesh material made of conductive metal wires woven vertically and horizontally, it is easy to provide the first anode with many holes and to form the upper surface of the first anode into the concave surface described above. The water-absorbing member may be composed of threads bundled together in the same length direction, or a sponge. If the water-absorbing member is made of threads, the bundled threads will become water-absorbent due to capillary action, so the threads do not need to be water-absorbent. However, the threads may be made of a water-absorbent material. In this case, not only due to capillary action but also due to the fibers absorbing the solution, the solution that has accumulated at the bottom of the container will spontaneously move toward the electrode surface, for example, rise.

[0016] The carbon dioxide reducing device of the present application may include a water-retaining sheet that covers the electrode surface and is made of a material that has water-retaining properties. The presence of a water-retaining sheet makes it easy to spread the aqueous solution soaked in the water-retaining sheet in the form of a film over a wide area of ​​the electrode surface. The water-retaining sheet can be made of, for example, a resin with water-retaining properties or paper. The first anode may have water retention properties. This makes it easier for the aqueous solution to exist in a film-like state on the electrode surface of the first anode, even without a water retention sheet. Depending on how you look at it, in this case, the first anode can be considered to also function as a water retention sheet. In this case, the aqueous solution may exist in a film-like state not only on the electrode surface of the first anode but also inside the first anode, but the aqueous solution will still exist in a film-like state over at least a certain wide area on the electrode surface of the first anode. To provide the first anode with water retention properties, the first anode can be made of, for example, a woven or nonwoven fabric made of carbon fiber, which is a fiber having electrical conductivity. Alternatively, the first anode can be provided with water retention properties by using, for example, a conductive sponge (described below) formed into a sheet shape.

[0017] The first anode may be configured by a conductive sponge, which is a sponge made of a conductive material, and the electrode surface may be the surface of the conductive sponge. For example, there exists a sponge composed of small hollow spheres made of carbon atoms arranged three-dimensionally so that the internal spaces of adjacent spheres are interconnected in the length, width, and height directions. Carbon is, of course, electrically conductive. Such a conductive sponge can be used as a first anode, and its surface can also be used as an electrode surface. Even when the first anode is made of a conductive sponge, the electrode surface can be made concave as described above. Furthermore, when the first anode is made of a conductive sponge, the aqueous solution that seeps out onto the upper side of the conductive sponge becomes a layer of aqueous solution on the first anode. Therefore, when the first anode is made of a conductive sponge, there is no particular need for the water-retaining sheet described above, which is useful for creating a layer of aqueous solution on the electrode surface. When the first anode is formed of a conductive sponge, the absorbent member can be formed of either the bundle of fibers or a sponge. On the other hand, when the first anode is formed of a conductive sponge, the supply member has an absorbent sponge made of a water-absorbing and conductive material, one end of which is immersed in the aqueous solution tank and the other end of which extends to or near the electrode surface, so that the aqueous solution in the aqueous solution tank is absorbed by the absorbent sponge and is supplied to the surface of the electrode surface, and the conductive sponge and the absorbent sponge can be formed integrally. By configuring the water-absorbing member and the first anode from a single conductive sponge (more precisely, a single conductive sponge and water-absorbing sponge), it is possible to reduce the number of parts, thereby simplifying the configuration of the carbon dioxide reduction device. Even in this case, the aforementioned benefit of being able to omit parts that require external energy input is maintained.

[0018] The power supply may be configured to apply a pulsed high voltage of 30 Hz to 500 Hz between the first cathode and the first anode. When the first cathode is a plurality of needle-like electrodes, the power supply typically maintains the plurality of needle-like electrodes at the same potential. The inventors of the present application have discovered that exposing an aqueous solution to a corona discharge promotes a specific reaction. Separately, the inventors have discovered that the specific reaction occurs most frequently at the moment when a large potential difference occurs between a pair of the first cathode and the first anode (the moment (or the time period) when a graph with time on the horizontal axis and potential difference on the vertical axis rises). By applying a pulse voltage (pulsed high voltage) between the first cathode and the first anode, the moment when a large potential difference occurs between the first cathode and the first anode can be repeated the same number of times as the number of pulses. As a result, it is possible to increase the amount of specific reaction that can be caused by the carbon dioxide reduction device, and ultimately to reduce a large amount of carbon dioxide in the air. When the voltage applied between the first cathode and the first anode is pulsed, the lower limit of the frequency of the pulse voltage is set to the above value because 30 Hz, that is, 30 times per second, will significantly increase the effect of reducing carbon dioxide emissions. On the other hand, the upper limit of the frequency of the pulse voltage is set to the above value because it is extremely difficult to generate a pulse voltage with a higher frequency. The voltage applied between the first cathode and the first anode is preferably between 4000V and 11000V, whether the voltage is pulsed or not. The reason why the lower limit of the potential of the pulse voltage is set to 4000 V is that if the potential difference between the first cathode and the first anode is smaller than that, the amount of discharge when corona discharge occurs will be small, and the specific reaction may not occur sufficiently. Note that corona discharge as referred to in this application also includes dark current discharge. The reason why the upper limit of the potential of the pulse voltage is set to 11000 V is that if the potential difference between the first cathode and the first anode is larger than that, the discharge occurring between the first cathode and the first anode may become a spark discharge accompanied by sparks, which may increase power consumption or cause severe deterioration of the first cathode, the first anode, and / or their surrounding components.

[0019] As described above, the carbon dioxide reduction device of the present invention includes the first cathode and the first anode. On the other hand, the present invention may also include a second cathode and a second anode in addition to the first cathode and the first anode. For example, the carbon dioxide reduction device according to the present invention may include a second anode, which is an electrode provided near the exhaust port, and a second cathode, which is an electrode paired with the second anode and positioned closer to the center of the container than the second anode, to which a negative voltage relative to the second anode is applied. In this case, the power supply device applies a voltage of a potential that generates a corona discharge between the second cathode and the second anode, and the ionic wind generated by the corona discharge generated between the second cathode and the second anode is exhausted from the exhaust port together with the air accelerated by the ionic wind. As a result, the ionic wind generated by the corona discharge generated between the second cathode and the second anode is exhausted from the exhaust port together with the air accelerated by the ionic wind. In other words, the first cathode and first anode are intended to efficiently collide the ionic wind and air with the aqueous solution, while the second cathode and second anode have the function of efficiently discharging the ionic wind and air (the air containing substances produced by specific reactions, etc.) from the container through the exhaust port. This creates a negative pressure inside the container, which allows air to be efficiently drawn into the container through the air intake, and also helps the carbon dioxide reduction device to efficiently reduce carbon dioxide. Here, the second anode may be a cylindrical electrode with both ends open, and may be fitted into the exhaust port. For example, by making the second anode a cylindrical electrode with both ends open and fitting it into the exhaust port, it becomes possible to direct the flow of ionic wind in a predetermined direction through the cylindrical second anode, i.e., through the exhaust port. If the second cathode is, for example, a needle-shaped electrode with its length parallel to the axis of the cylindrical second anode and the second cathode is arranged coaxially with the cylindrical second anode, it is possible to direct the flow of ionic wind to pass through the cylindrical second anode. This causes the flow of ionic wind to naturally pass through the cylindrical second anode, i.e., through the exhaust port, and exhaust from the container progresses. When the first cathode and the second cathode are both a single needle-like electrode, the first cathode and the second cathode may be a series of needle-like electrodes. By integrating the first cathode and the second cathode, the circuit configuration can be simplified. In this case, the lower side of a single needle-like electrode extending vertically can be the first cathode, and the upper side can be the second cathode. In this case, typically, a cylindrical second anode that is open at the top and bottom is placed coaxially with the needle-like electrode that serves as both the first and second cathodes and above the needle-like electrode.

[0020] The carbon dioxide reduction device of the present application uses an aqueous solution containing sodium ions. The aqueous solution may be a sodium chlorite aqueous solution or a sodium chloride aqueous solution. Sodium chloride, in particular, is common salt, and is easy to obtain and inexpensive. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a cross-sectional view schematically showing the structure of a carbon dioxide reducing device according to a first embodiment. [Figure 2] FIG. 2 is a perspective view of a planar electrode and a water-retaining sheet included in the carbon dioxide reduction device shown in FIG. 1. [Figure 3] FIG. 2 is a circuit diagram of a pulse power supply included in the carbon dioxide reduction device shown in FIG. 1. [Figure 4] 2 is a diagram illustrating an example of a pulse waveform input to a high-voltage power supply device in the carbon dioxide reduction device shown in FIG. 1. [Figure 5] FIG. 10 is a cross-sectional view schematically showing the structure of a carbon dioxide reduction device according to a first modified example. [Figure 6] (A) is a front view showing the configuration of an example of an electrode body before being rolled, (B) is a front view showing the configuration of another example of an electrode body before being rolled, and (C) is a bottom view showing the configuration of the rolled electrode body. [Figure 7] FIG. 10 is a cross-sectional view schematically showing the structure of a carbon dioxide reduction device according to a second modification. [Figure 8] FIG. 10 is a cross-sectional view schematically showing the structure of a carbon dioxide reducing device according to a second embodiment. [Figure 9] FIG. 11 is a cross-sectional view schematically showing the structure of a carbon dioxide reduction device according to a third modified example. [Figure 10] FIG. 10 is a cross-sectional view schematically showing the structure of a carbon dioxide reduction device according to the first embodiment when the device is modified so that the water-retaining sheet is omitted and the planar electrode has water-retaining properties. [Figure 11] FIG. 10 is a cross-sectional view schematically showing the structure of a carbon dioxide reduction device according to a second embodiment, which is modified so that the water-retaining sheet is omitted and the sheet electrode has water-retaining properties. [Figure 12] FIG. 10 is a cross-sectional view schematically showing the structure of a carbon dioxide reduction device according to Modification 3, which is modified so that the water-retaining sheet is omitted and the planar electrode has water-retaining properties. DETAILED DESCRIPTION OF THE INVENTION

[0022] The carbon dioxide reducing apparatuses according to the first and second embodiments and their modified examples will be described below with reference to the drawings. In the description of each embodiment and modification, common elements will be assigned common reference numerals, and common descriptions will be omitted in some cases. Furthermore, each configuration described in each embodiment and modification can be applied to each embodiment and modification, unless there is a contradiction.

[0023] First Embodiment FIG. 1 is a cross-sectional view showing a schematic structure of a carbon dioxide reducing device according to a first embodiment. The carbon dioxide reducing device according to the first embodiment includes a container 10 as shown in FIG. 1. The container 10 is airtight and watertight, and in this embodiment, although not limited thereto, has a vertically elongated cylindrical shape. The container 10 can be made of, for example, resin or metal. It is preferable that the metal used for the container 10 is non-conductive. An opening, namely, an intake port 11, is provided on the side of the container 10, although this is not limited to this. The intake port 11 is a hole for introducing air into the container 10, and the details of its configuration are not important as long as its function is guaranteed. The size and shape of the intake port 11 can be determined as appropriate, but in this embodiment, the intake port 11 is a circle with an appropriate diameter. The edge of the intake port 11 is connected to the edge of the base end of the duct 12, which is a pipe, without any gap. The duct 12 is a passage that guides the air drawn in through the intake port 11 to the range α described below. The details of its configuration are not important or essential as long as it can perform this function. The duct 12 can be made of an airtight material, for example, the same material as the container 10. Although this is not necessary in this embodiment, the duct 12 is made of the same material as the container 10 and is integrally formed therewith. The duct 12 extends horizontally from its base end to, but is not limited to, the axis of the container 10, and then bends vertically downward at the axis of the container 10. The tip of the duct 12 opens downward to facilitate collision of the ionic wind and air with the aqueous solution in a film form, as described below. The horizontal portion of the duct 12 proximal to the portion where the duct 12 intersects with the axis of the container 10 is cylindrical with an inner diameter equal to the diameter of the intake port 11, since the intake port 11 is circular. The vertical portion of the duct 12 distal to the portion where the duct 12 intersects with the axis of the container 10 is cylindrical with a larger diameter than the portion proximal to the distal portion. However, the duct 12 may have the same cross-sectional shape along its entire length. The opening at the lower end of the vertical portion of the duct 12 is circular, but is not limited to this, and its center is located on the axis of the container 10. In this embodiment, although not limited thereto, the container 10 has an opening, an exhaust port 13, at its upper portion. The exhaust port 13 is a hole for discharging air and the like from the container 10 to the outside of the container 10, and the details of its configuration are not important as long as its function is guaranteed. The size and shape of the exhaust port 13 can be determined as appropriate, but in this embodiment, the exhaust port 13 is circular and has an appropriate diameter. In this embodiment, the portion of the container 10 connected to the exhaust port 13 narrows upward like an inverted funnel, but this is not necessarily the case. In addition, although not limited thereto, in this embodiment, the center of the circular exhaust port 13 is positioned at a position through which the axis of the container 10 passes.

[0024] The container 10 is provided with three electrodes: a needle-like electrode 21, a surface electrode 22, and a cylindrical electrode 23. The needle-like electrode 21, the surface electrode 22, and the cylindrical electrode 23 can all be made of a conductive metal, such as iron or copper. Of these, the needle electrode 21 is supplied with a voltage having a relatively negative potential compared to the surface electrode 22 and the cylindrical electrode 23 . The needle electrode 21 is a needle-shaped electrode that extends in the vertical direction. In this embodiment, although not limited thereto, the needle electrode 21 is disposed coaxially with the container 10 so as to penetrate the upper portion of the duct 12. A portion 21A of the needle electrode 21 located inside the duct 12 corresponds to the first cathode in this application (hereinafter, this portion may be referred to as the first cathode 21A), and a portion 21B of the needle electrode 21 exposed to the outside (upper side) of the duct 12 corresponds to the second cathode in this application (hereinafter, this portion may be referred to as the second cathode 21B). In this embodiment, the first cathode 21A and the second cathode 21B are integrated as a part and a remainder of one needle electrode 21, but this is not necessarily required. Although not limited to this, in this embodiment, the planar electrode 22 is located relatively lower than the needle-like electrode 21. The planar electrode 22 is an electrode having an electrode surface 22A that extends in a planar shape facing the first cathode 21A. The reason why the planar electrode 22 has a planar electrode surface 22A is that an aqueous solution, which will be described later, is present in a film-like, spreading state on the electrode surface 22A. The surface electrode 22 may be configured such that the electrode surface 22A is horizontal (for example, it may be a simple plate-like body placed horizontally) as long as it is possible to have the aqueous solution described below present in the form of a film having a spreading shape on the electrode surface 22A. However, the present invention is not limited to this, and the surface electrode 22 in this embodiment is configured so that the center of the electrode surface 22A is concave downward, as shown in FIG. 2. The sheet electrode 22 is plate-shaped and, in this embodiment, is disposed so as to be essentially horizontal. More specifically, in the example shown in FIG. 2(A), the sheet electrode 22 is configured so that its electrode surface 22A is horizontal up to a predetermined distance from the center (the horizontal range is not limited to this, but is circular in this embodiment), and its outer periphery is smoothly raised. Although not limited to this, since the sheet electrode 22 in this example is plate-shaped, the sheet electrode 22 has a shape that can be described as a pot shape overall. Such a sheet electrode 22 is disposed and used so that the center of the electrode surface 22A is located directly below the needle electrode 21. In the example shown in FIG. 2(B), the sheet electrode 22 is shaped so that its electrode surface 22A conforms to a portion of the outer surface of a virtual sphere. Although not limited to this, the sheet electrode 22 in this example is also plate-shaped and smoothly curved along the outer surface of the virtual sphere. This sheet electrode 22 is also used so that the center of the electrode surface 22A is positioned directly below the needle electrode 21. It is preferable to use the needle electrode 21 so that the lower end of the first cathode 21A is positioned at the center of the virtual sphere on whose outer surface the electrode surface 22A rests. This ensures that the distance from the tip of the first cathode 21A to the electrode surface 22A is equal at every part of the electrode surface 22A, which is expected to generate a corona discharge evenly across the entire surface of the electrode surface 22 and the first cathode 21A. In this embodiment, the planar electrode 22 shown in FIG. 2(A) is used, although it is not limited to this. Although not limited thereto, the sheet electrode 22 in this embodiment has holes (not shown) through which the aqueous solution (also described below) absorbed by the fiber rod (described later) passes from the bottom to the top of the sheet electrode 22. Theoretically, there is no problem if there is at least one hole, but there can be multiple or many holes. In this embodiment, the sheet electrode 22 is made of a mesh material formed by weaving conductive metal wires vertically and horizontally. Therefore, the sheet electrode 22 has many holes.

[0025] The planar electrode 22 is supported from below by an electrode support member 24 provided inside the container 10 . The electrode support member 24 is shaped as a body of revolution about the axis of the vessel 10. Although not limited to this, the electrode support member 24 may be made of the same material as the vessel 10 and be integral with the vessel 10. The electrode support member 24 is a dish-shaped member extending from the inner peripheral surface of the vessel 10 toward the axial direction of the vessel 10. The upper surface of the electrode support member 24 is a concave surface that is curved in accordance with the lower surface of the pan-shaped planar electrode 22. By fitting the planar electrode 22 inside the electrode support member 24, the planar electrode 22 is stably supported from below by the electrode support member 24. The configuration of the electrode support member 24 does not have to be as described above, as long as it is capable of supporting the planar electrode 22. A hole 24A is formed near the center of the electrode support member 24. Although not limited to this, the hole 24A has a circular shape centered at the center of the electrode support member 24 when viewed from above. The hole 24A is used to allow the aqueous solution sucked up by the fiber rod (described later) to come into contact with the underside of the sheet electrode 22 made of a mesh material.

[0026] In this embodiment, although not limited thereto, a water retention sheet 25 is placed over the electrode surface 22A of the planar electrode 22. The water retention sheet 25 serves to maintain the aqueous solution in a film form on the electrode surface 22A. The water retention sheet 25 is a sheet made of a material with water retention properties, and in this embodiment, although not limited thereto, is shaped to fit the entire surface of the electrode surface 22A (see FIGS. 2(A) and (B)). The aqueous solution soaks into the water retention sheet 25 and ideally maintains a film form over the entire surface of the electrode surface 22A. The water-retaining material that constitutes the water-retaining sheet 25 is, for example, a water-retaining resin, paper, cloth, etc. The cloth may be a woven fabric or a nonwoven fabric. The water-retaining sheet 25 in this embodiment is made of, but is not limited to, paper. There is no particular limitation on the thickness of the water retention sheet 25. The thickness of the water retention sheet 25 can be, for example, about 0.5 mm to 3 mm. The sheet electrode 22 can be made of a material with water retention properties. In this case, the sheet electrode 22 can be in a sheet form. There are no particular limitations on the thickness of the sheet-like sheet electrode 22, but it can be, for example, similar to the thickness of the water retention sheet 25 described above. If the sheet electrode 22 has water retention properties, it is easier to maintain a film of aqueous solution on the electrode surface 22A of the sheet electrode 22, even if the water retention sheet 25 is omitted. Depending on how you look at it, in this case, the sheet electrode 22 can be considered to also serve as the water retention sheet 25. To impart water retention properties to the sheet electrode 22, for example, the sheet electrode 22 can be made of a woven or nonwoven fabric made of conductive fibers (typically carbon fibers). However, if the sheet electrode 22 is made of a nonwoven fabric made of carbon fibers, discharge from the first cathode 21A tends to occur at the tips of the carbon fibers slightly protruding from the electrode surface 22A of the sheet electrode 22. Therefore, it is preferable to make the sheet electrode 22 of a woven fabric rather than a nonwoven fabric. An example of a woven fabric made of carbon fiber that can be used as the water-retaining sheet electrode 22 is "Carbon Fiber Paper (GDL (Gas Diffusion Layer))" (trademark) manufactured and sold by Mitsubishi Chemical Corporation. Alternatively, the sheet electrode 22 can be provided with water-retaining properties by using, for example, a conductive sponge (described below) formed into a relatively thin sheet. In this case, the aqueous solution may exist in a film form not only on the electrode surface 22A of the sheet electrode 22 but also inside the sheet electrode 22. However, the aqueous solution remains in a film form over at least a relatively wide area on the electrode surface 22A of the sheet electrode 22. FIG. 10 shows a diagram corresponding to FIG. 1 of a carbon dioxide reduction device in which the sheet electrode 22 has water retention properties and the water retention sheet 25 is omitted.

[0027] As described above, the electrode support member 24 has a hole 24A formed therein. A cylindrical rod support member 26 extends downward from the edge of the hole 24A. The upper end of the rod support member 26 is connected to the edge of the hole 24A without any gap. The lower end of the rod support member 26 is submerged in a predetermined amount of aqueous solution (described below) stored at the bottom of the container 10. A fiber rod 27 is inserted into the rod support member 26. The rod support member 26 has the function of supporting the fiber rod 27. As long as this function is maintained, the configuration of the rod support member 26 may be different from that described above. For example, as will be described later, it is the lower end of the fiber rod 27 that should be submerged in the aqueous solution, but the lower end of the rod support member 26 does not necessarily need to be submerged in the aqueous solution. The fiber rod 27 is formed by bundling fibers aligned in the length direction and forming them into a rod shape. The fibers constituting the fiber rod 27 are made of, for example, resin, preferably a water-absorbent resin. Although not limited to this, the fibers constituting the fiber rod 27 in this embodiment are water-absorbent. The fibers constituting the fiber rod 27 may be natural fibers. It is also well known that some natural fibers have water-absorbent properties. The fiber rod 27 is an example of a water-absorbing member in this application, and the combination of the fiber rod 27 and the rod support member 26 is an example of a supply member in this application. The fiber rod 27 is generally rod-shaped, and in this embodiment, although not limited to, is formed into a cylindrical shape, and its diameter is approximately equal to the inner diameter of the cylindrical rod support member 26. The fiber rod 27 is fixed to the rod support member 26 by being inserted inside the rod support member 26. One end of the fiber rod 27, which is the lower end in this embodiment, is submerged in an aqueous solution, which will be described later, and the other end of the fiber rod 27, which is the upper end in this embodiment, is in contact with the lower surface of the planar electrode 22. The fiber rod 27 has the function of absorbing the aqueous solution from its lower end, which is submerged in the aqueous solution, all the way up to the sheet electrode 22. More precisely, the upper end face of the fiber rod 27 abuts the lower surface of the sheet electrode 22. The aqueous solution that reaches the lower surface of the sheet electrode 22 passes through the numerous openings in the sheet electrode 22, which is made of a mesh material in this embodiment, and then reaches the upper side of the sheet electrode 22. If the sheet electrode 22 is given water retention properties and the water retention sheet 25 is omitted, the upper end face of the fiber rod 27 abuts the lower surface of the sheet electrode 22. This allows the aqueous solution to permeate the sheet electrode 22 and seep out onto the electrode surface 22A, which is the upper surface of the sheet electrode 22. This results in the aqueous solution being present inside the sheet electrode 22, but also in a state where a film of the aqueous solution is present over at least a certain area on the electrode surface 22A of the sheet electrode 22. Fiber rod 27 uses capillary action through gaps between the fibers to suck up the aqueous solution that has accumulated at the bottom of container 10. If the fibers that make up fiber rod 27 are water-absorbent, the aqueous solution that has accumulated at the bottom of container 10 will be sucked up toward electrode surface 22A not only by capillary action but also by the fibers absorbing the aqueous solution. Fiber rod 27 is an example of a water-absorbing member in the present application, or more specifically, a water-absorbing member that spontaneously sucks up an aqueous solution without receiving an external supply of energy. Fiber rod 27 can be obtained from Asahi Textile Industry Co., Ltd., which produces fiber rods under the product name "Fiber Rod" on a made-to-order basis. Fiber rod 27 can also be replaced with a general sponge made of natural materials or resin.

[0028] The cylindrical electrode 23 is located closer to the exhaust port 13 relative to the needle electrode 21. The cylindrical electrode 23 is located above the needle electrode 21, and although not limited to this, in this embodiment, the cylindrical electrode 23 is fitted inside the exhaust port 13. The cylindrical electrode 23 is cylindrical or ring-shaped, and the diameter of its outer surface is equal to the diameter of the inner surface of the exhaust port 13. As a result, the cylindrical electrode 23 is attached inside the exhaust port 13 with its outer surface in contact with the inner surface of the exhaust port 13 without any gaps. The center of the cylindrical electrode 23, which is circular in plan view, is located on the axis of the container 10. Therefore, the center of the cylindrical electrode 23 is located directly above the needle electrode 21.

[0029] A control unit 30 is provided at an appropriate position on the container 10, in this embodiment on the left side in FIG. An operation switch 31 (not shown in FIG. 1 but shown in FIG. 3) is provided on the outside of the control unit 30. The operation switch 31 is used by the user to turn the carbon dioxide reduction device on and off, as will be described later. The operation switch 31 may be any suitable known or well-known switch, such as a physical switch that switches on and off by moving it, or a touch panel that switches on and off by touching it. The inside of the control unit 30 is hollow, and a pulse power supply 40, which is a power supply, is disposed therein. The pulse power supply 40 is a power supply for applying a pulsed high voltage, which will be described later, between the needle electrode 21 and the planar electrode 22 and the cylindrical electrode 23, more specifically, between the first cathode 21A and the planar electrode 22 and between the second cathode 21B and the cylindrical electrode 23. In this embodiment, the voltage applied between the two pairs of cathode and anode is a pulsed voltage, but this is not necessarily the case. If the voltage is not a pulsed voltage, the pulse power supply 40 may simply be a power supply that generates a constant voltage. Although not limited to this in this embodiment, the pulse power supply 40 is configured to apply a pulsed high voltage of 4000 V to 11000 V at 30 Hz to 500 Hz as a pulse voltage between the first cathode 21A and the planar electrode 22. A similar pulse voltage is also applied between the second cathode 21B and the cylindrical electrode 23. Such a pulse voltage can be generated by using a power supply device designed to apply a pulse voltage. To be able to apply such a voltage, the pulse power supply 40 is connected to the needle electrode 21, the planar electrode 22, and the cylindrical electrode 23, as required, by conductors.

[0030] 3 shows a circuit diagram of the pulse power supply 40. In FIG. 3, the pulse power supply 40 is made up of parts other than the operation switch 31, the needle electrode 21, the planar electrode 22, and the cylindrical electrode 23. The pulsed power supply 40 in this embodiment includes a high-voltage power supply, as will be described later. The portion of the pulsed power supply 40 preceding the high-voltage power supply determines the shape of the pulse wave, and may be called a pulse waveform determining device. As shown in FIG. 3, the pulse power supply 40 includes a computer 41. The computer 41 is an information processing device, and the information processing it performs can be freely changed depending on the software installed. The computer 41 may be a computer device such as a personal computer, a single-board computer such as the Raspberry Pi manufactured and sold by the UK Raspberry Pi Foundation, or an integrated circuit (IC). In any case, the computer 41 in this embodiment outputs a reference square wave, which is a square wave with a certain frequency and a certain duty ratio. The computer 41 is also connected to the operation switch 31 and receives input from the operation switch 31. When the computer 41 receives input from the operation switch 31, for example, an input (ON input) to start the operation of the carbon dioxide reduction device, it generates and outputs a reference square wave and turns on the power of the high-voltage power supply device described below. When the computer 41 receives an input from the operation switch 31, for example, an input (OFF input) indicating that the operation of the carbon dioxide reduction device is to be terminated, the computer 41 stops generating the reference square wave and turns off the power to the high-voltage power supply device described below. The computer 41 capable of performing the above-described information processing is naturally publicly known or well known, whether the computer 41 is a computer device, a single-board computer, or an IC, and therefore further explanation will be omitted.

[0031] The reference square wave is input from the computer 41 via a first connection line 42A to the base of an NPN transistor 43. The emitter of the NPN transistor 43 is grounded (GRD). The collector of the NPN transistor 43 is connected to the base of a PNP transistor 45 via a second connection line 42B with a resistor 44 provided midway. The emitter of the PNP transistor 45 is connected to a 12 V power supply, and the collector of the PNP transistor 45 is connected to a high voltage power supply 46 by a third connection line 42C. The high-voltage power supply 46 is a known or publicly known device that outputs a pulsed high voltage corresponding to a pulse waveform (described later) input via the third connection line 42C. The high-voltage power supply 46 is grounded (GRD) and generates a high voltage with the potential of GRD set to 0 V as a reference. In this embodiment, although not limited thereto, the voltage that the high-voltage power supply 46 can generate is between −4000 V and −12000 V, and in this embodiment, although not limited thereto, it is −8000 V. The high-voltage power supply device 46 is connected to the needle electrode 21 by a fourth connection line 42D. The pulsed high voltage generated by the high-voltage power supply device 46 is sent to the needle electrode 21 via the fourth connection line 42D. On the other hand, the already-described sheet electrode 22 and cylindrical electrode 23 are provided below and above the needle electrode 21, respectively. Both the sheet electrode 22 and the cylindrical electrode 23 are grounded (GRD). Although not limited to this, in this embodiment, the sheet electrode 22 and the cylindrical electrode 23 are connected to each other by a fifth connection line 42E and are grounded via the fifth connection line 42E. Although it is not necessary to explain, the first connection line 42A to the fifth connection line 42E are all conductive conductors.

[0032] The method of use and operation of the carbon dioxide reducing device described above will now be described. To use the carbon dioxide reduction device, a user places the carbon dioxide reduction device in an appropriate location, for example, indoors. The "room" where the carbon dioxide reduction device is placed is typically the interior of a property or an automobile. The carbon dioxide reduction device can be made small and lightweight enough to be portable. Around the time when the carbon dioxide reduction device is placed at an appropriate position in the room, the user stores aqueous solution 50 in the bottom of container 10 (FIG. 1). Although not limited to this, in this embodiment, a certain area below planar electrode 22 of container 10 is referred to as an aqueous solution tank in the present application, where aqueous solution 50 is stored. Aqueous solution 50 contains sodium ions Na +The aqueous solution 50 may be, for example, a sodium chlorite (NaClO2) aqueous solution or a sodium chloride (NaCl) aqueous solution. In this embodiment, a sodium chloride aqueous solution is used, although not limited thereto. The aqueous solution 50 may be poured onto the bottom of the container 10 using a hose from the exhaust port 13. If the water-retaining sheet 25, the planar electrode 22, the fiber rod 27, etc., get in the way, it is of course possible to make them detachable from the electrode support member 24 and the rod support member 26, and then pour the aqueous solution 50 onto the bottom of the container 10 after removing them. Alternatively, a freely openable inlet for pouring the aqueous solution 50 into the container 10 may be provided on the side of the container 10 near the bottom, and the aqueous solution 50 may be poured into the container 10 through this inlet. The aqueous solution 50 stored at the bottom of the container 10 should not come into contact with the planar electrode 22. When aqueous solution 50 is collected at the bottom of container 10, the lower end of fiber rod 27 is submerged in aqueous solution 50. Due to capillary action, or in addition to this, due to the water-absorbing properties of the fibers that make up fiber rod 27, fiber rod 27 absorbs aqueous solution 50. The aqueous solution 50 moves up fiber rod 27 and, when it reaches the upper end of fiber rod 27, reaches the upper side of sheet electrode 22 through the numerous holes in sheet electrode 22 made of a mesh material. A water-retaining sheet 25, which has water-retaining properties, is placed on top of sheet electrode 22. The aqueous solution 50 is absorbed into water-retaining sheet 25, and although it may take some time, it will eventually permeate the entire surface of water-retaining sheet 25. As a result, the aqueous solution 50 is present in the form of a film on the electrode surface 22A, which is the upper surface of the sheet electrode 22, with a spread according to the thickness and size of the water retention sheet 25. The supply of the aqueous solution 50 to the water retention sheet 25 as described above is carried out continuously as long as the aqueous solution 50 at the bottom of the container 10 does not run out.

[0033] After placing the carbon dioxide reduction device in an appropriate position indoors and allowing the aqueous solution 50 to permeate the entire water retention sheet 25, the user operates the operation switch 31 to input an ON input, which is an input for starting the operation of the carbon dioxide reduction device. The ON input is input to the computer 41. Upon receiving the ON input, the computer 41 outputs a reference square wave, which is a square wave with a certain frequency and a certain duty ratio. The frequency and duty ratio of the square wave output by the computer 41 may always be the same or may be variable, for example, depending on an input from the operation switch 31, but in this embodiment they are always the same. The frequency and duty ratio of the square wave are uniquely determined by data that respectively specify the frequency and duty ratio, which are stored in a memory provided in the computer 41, for example. Upon receiving the ON input, computer 41 also turns on the power of high-voltage power supply device 46. This puts high-voltage power supply device 46 into a state in which it can generate a pulse voltage, which is a pulsed high voltage, when a pulse waveform, which will be described later, is input.

[0034] The computer 41 generates a reference square wave, which is a square wave. The reference square wave is conceptually shown in FIG. The reference square wave is input from the computer 41 to the base of the NPN transistor 43 via the first connection line 42A. The voltage of the reference square wave (the potential difference between the ON state portion and the OFF state portion) is 5V, although this is not limited to this. A reference waveform having the same frequency and duty ratio as the reference square wave created by the computer 41 but amplified to a voltage of 12V is output from the collector of the NPN transistor 43. The amplified reference waveform is output from the collector of the NPN transistor 43 to the second connection line 42B, passes through the resistor 42, and is input to the base of the PNP transistor 45. The collector of the PNP transistor 45 outputs a reference waveform with the same frequency and duty ratio as the reference square wave generated by the computer 41, but with amplified current. Hereinafter, this reference waveform will be referred to as a "pulse waveform." A conceptual representation of the pulse waveform is shown in FIG. 3, labeled Y. As described above, pulse waveform Y is the same as the reference waveform generated by the computer 41 in terms of frequency and duty ratio, but is no longer a square wave. Pulse waveform Y has a nearly vertical rise when switching from the OFF state to the ON state (the rise of the waveform when plotted with time on the horizontal axis and potential difference on the vertical axis). In the ON state, the potential remains approximately constant, but the potential does not immediately drop when switching from the ON state to the OFF state; instead, the potential decreases approximately linearly. The waveform of the pulse waveform differs from the reference rectangular waveform generated by the computer 41 because the NPN transistor 43 and the PNP transistor 45 between the computer 41 and the high voltage power supply 46 act like a capacitor. An example of the pulse waveform Y is shown in Figure 4. The pulse waveform Y shown in Figure 4 has a frequency of 50 Hz and a duty ratio of 10%. The duty ratio is set to a relatively small value of 10% for the following reasons. The rising portion of the pulse voltage is beneficial for inducing a specific reaction. In contrast, the portion of the pulse voltage after the rising portion is thought to contribute less to inducing a specific reaction. If this is the case, the duty ratio should be made as small as possible and the time for the portion of the pulse waveform Y where the potential drops should be made longer, so that the portion of the pulse voltage where the potential drops most should be at a sufficiently low potential. In other words, if the time for the portion of the pulse waveform Y where the potential drops cannot be made sufficiently long, the rising portion of the next pulse voltage will start from a relatively high voltage, which may result in an insufficient potential difference being secured in the pulse voltage. However, such a device is used in the pulse power supply 40 of this embodiment to generate a pulse voltage with a relatively high frequency and a high voltage in the high-voltage power supply 46, which does not have a very high performance. Therefore, if the high-voltage power supply 46 alone can generate a pulse voltage with a relatively high frequency and a high voltage, such a device is not necessarily required.

[0035] A pulse waveform is input to the high-voltage power supply device 46 from the collector of the PNP transistor 45 via the third connection line 42C. The high voltage power supply 46 generates a pulsed high voltage in accordance with the received pulse waveform. A pulsed high voltage is applied to the needle electrode 21 from the high-voltage power supply 46 via the fourth connection line 42D. The high-voltage power supply 46 is grounded, and the planar electrode 22 and the cylindrical electrode 23 are also grounded, so the potential difference between the needle electrode 21 and the planar electrode 22 and the cylindrical electrode 23 corresponds to the pulse voltage generated by the high-voltage power supply 46. In other words, a high voltage corresponding to the pulse voltage is applied between the needle electrode 21 and the planar electrode 22 and the cylindrical electrode 23. The potential difference between the needle electrode 21 and the planar electrode 22 and the cylindrical electrode 23 is set to 4000 V to 11000 V, and in this embodiment, it is set to 8000 V, although it is not limited to this. As a result, corona discharges occur between the needle-shaped electrode 21 (more precisely, the first cathode 21A) and the planar electrode 22, and between the needle-shaped electrode 21 (more precisely, the second cathode 21B) and the cylindrical electrode 23, in which electrons fly through the air from the former to the latter. The electrode surface 22A of the planar electrode 22 is concave as described above. Therefore, discharge from the first cathode 21A of the needle-like electrode 21 occurs relatively evenly across the entire electrode surface 22A. If the distance from the lower end of the first cathode 21A to the concave electrode surface 22A is always the same regardless of the position on the electrode surface 22A, discharge from the first cathode 21A to the electrode surface 22A of the planar electrode 22 will ideally occur with equal probability across all parts of the electrode surface 22A.

[0036] In this state, air enters the container 10 through the air inlet 11. As is well known, air contains water vapor (i.e., water H2O) in addition to nitrogen, oxygen, and carbon dioxide. The air passes through the duct 12 and reaches the space between the first cathode 21A of the needle electrode 21 and the surface electrode 22. In this space (the area roughly surrounded by the dashed line α in FIG. 1, hereinafter referred to as the "α range"), corona discharge (or dark current discharge) occurs as described above. In the α range, electrons e are emitted from the first cathode 21A of the needle electrode 21 toward the planar electrode 22. - is being released. Emitted electron e - When these particles collide with oxygen O2 in the air, ozone O3 is produced by the chemical reaction shown in the following chemical formula (1). 3O2+6e - →2O3……(1) Also, in the α range, electron e - collides with ozone O3 and water vapor H2O, and oxygen O2 and hydroxide ions OH - is generated. O3+H2O+2e - →O2+2OH - ……(2) negatively charged hydroxide ion OH - is accelerated by being attracted to the planar electrode 22 (voltage 0V) which has a positive potential relative to the first cathode 21A. This is the ionic wind. The ionic wind and air travel downward and collide with the water retention sheet 25 arranged on the planar electrode 22, and microscopically, they collide with the aqueous solution 50 which has soaked into the water retention sheet 25. The first cathode 21A only needs to be capable of generating a corona discharge with respect to the planar electrode 22, and as a result, generating a downward ion wind in this embodiment in the direction toward the planar electrode 22. Therefore, the first cathode 21A does not need to be a part of the needle electrode 21.

[0037] Next, the following phenomenon occurs within the water retention sheet 25 (not exactly, the area roughly surrounded by the dashed line β in FIG. 1, hereinafter referred to as the "β range"). The water retention sheet 25 is located between the first cathode 21A and the planar electrode 22. Therefore, the aqueous solution 50, which is in the form of a film and has a certain degree of spread and is present within the water retention sheet 25, is exposed to a corona discharge. This is thought to cause the following reaction in which the water in the aqueous solution 50 is ionized. That is, the water (H2O) in the aqueous solution 50 is converted into hydrogen ions (H + ) and hydroxide ions (OH - ) is ionized. H2O→H + +OH - ...(3) In addition, hydroxide ions (OH) contained in the ionic wind - However, it is considered that the evaporation of the aqueous solution 50 occurs when the components of the aqueous solution 50 (chloride ions Cl - , water H2O) is thought to evaporate. In addition, the following chemical reactions also occur in the β range: Water H2O and sodium chloride NaCl are present in the aqueous solution 50. Sodium chloride ionizes in the aqueous solution 50 to form sodium ions Na + and chloride ions Cl - In addition, hydroxide ions OH - A part of the water H2O in the aqueous solution 50 is ionized to form hydrogen ions H + and hydroxide ions OH - and hydroxide ions OH - The amount of is increased more than usual in any part of the water retention sheet 25 due to the reaction of the above-mentioned chemical formula (3). In other words, in the aqueous solution 50, there are sodium ions Na + and hydroxide ion OH -This is the same even when the aqueous solution 50 is an aqueous solution of sodium chlorite (NaClO2). In a 50% aqueous solution, sodium ions Na + and hydroxide ion OH - reacts with carbon dioxide CO2 as shown in the following chemical equation (4) or (5) (these are specific reactions) to produce sodium carbonate Na2CO3 or sodium bicarbonate NaHCO3. In both of these reactions, carbon dioxide is decomposed, resulting in a reduction of carbon dioxide. 2Na + +2OH - +CO2→Na2CO3+H2O……(4) Na + +OH - +CO2→NaHCO3……(5) Whether the reaction is (4) or (5), the hydroxide ion OH - Sodium ions (Na) are required. + If there is sufficient hydroxide ion OH - The more sodium ions present, the more the reactions of chemical equations (4) and (5) are promoted. + A sufficient amount of OH can be easily achieved, for example, by increasing the concentration of sodium chloride NaCl in the aqueous solution 50. On the other hand, in this embodiment, the aqueous solution 50 is exposed to a corona discharge to ionize the water in the aqueous solution 50, thereby generating the hydroxide ions OH - The amount of is sufficient or at least greater than when the aqueous solution 50 is not exposed to corona discharge. As a result, the carbon dioxide reduction device of this embodiment can promote the reactions of chemical formulas (4) and (5), which are direct reactions for reducing carbon dioxide, thereby improving the carbon dioxide reduction performance. Sodium carbonate (Na2CO3) and sodium bicarbonate (NaHCO3) may remain dissolved in the aqueous solution 50 or may mix with the air. Carbon dioxide is reduced by fixing the carbon (C) in carbon dioxide (CO2) as sodium carbonate (Na2CO3) and sodium bicarbonate (NaHCO3). The specific reaction occurs every time the pulse power supply 40 applies a high voltage between the first cathode 21A and the planar electrode 22. Because the frequency of the pulsed high voltage is set to 30 Hz to 500 Hz, the specific reaction occurs 30 to 500 times per second. Therefore, this carbon dioxide reduction device reduces even more carbon dioxide.

[0038] Transpired chloride ions Cl - The air containing ozone O, water H2O, sodium carbonate Na2CO3, and sodium bicarbonate NaHCO3 moves upward and reaches the gap between the second cathode 21B of the needle electrode 21 and the cylindrical electrode 23. Corona discharge occurs there (the area roughly surrounded by the dashed line γ in FIG. 1, hereinafter referred to as the "γ range") as described above. In the γ range, electrons e - is being released. Emitted electron e - collide with oxygen O2 in the air, and ozone O3 is produced by the chemical reaction shown in chemical formula (1) above. Also, in the γ range, electron e - collides with ozone O3 and water vapor H2O, and oxygen O2 and hydroxide ions OH - is generated. negatively charged chloride ion Cl - and hydroxide ion OH - are attracted by the cylindrical electrode 23 (voltage 0 V) ​​which has a positive potential relative to the second cathode 21B, are accelerated, pass through the cylindrical electrode 23, and are released to the outside of the container 10 from the exhaust port 13 at the top of the container 10. This flow is the ionic wind. As the ionic wind is exhausted to the outside of the container 10, hydroxide ions OH - , chloride ion Cl - The air containing water H2O, ozone O3, sodium carbonate Na2CO3, and sodium bicarbonate NaHCO3 is discharged to the outside of the container 10. This creates a negative pressure inside the container 10, which promotes the flow of air into the container 10 from the air intake 11. The second cathode 21B and the cylindrical electrode 23 thus have the purpose of generating a corona discharge between them and generating an ion wind toward the exhaust port 13. Therefore, the second cathode 21B does not need to be part of the needle-like electrode 21, and the cylindrical electrode 23 does not need to be cylindrical. Also, the second cathode 21B and the first cathode 21A do not need to be integrated. These can be modified as long as the above-mentioned purpose can be achieved. Hydroxide ion OH - , chloride ion Cl - Since this carbon dioxide reduction device releases ozone O3 into the room, it also has the effect of sterilizing the air.

[0039] <Variation 1> Modification 1 will now be described. In Modification 1, the same components as those in the above-described embodiment will be assigned the same reference numerals as those used in the above-described embodiment, and overlapping descriptions will be omitted in some cases. The carbon dioxide reduction apparatus according to the first modification is almost the same as the carbon dioxide reduction apparatus described in the above embodiment. FIG. 5 is a cross-sectional view showing a schematic structure of the carbon dioxide reducing device according to the first modification. To explain only the differences, the carbon dioxide reduction device in Modification 1 does not have the planar electrode 22, water retention sheet 25, rod support member 26, or fiber rod 27 that are provided in the carbon dioxide reduction device in the above-mentioned embodiment. Moreover, instead of having these, the carbon dioxide reduction device in Modification 1 has a sponge body 29 that was not provided in the carbon dioxide reduction device in the above-mentioned embodiment. This is the only difference between the two carbon dioxide reduction devices.

[0040] The sponge body 29 is made of a conductive sponge made of a conductive material. An example of a conductive sponge is the graphene mesosponge developed by Associate Professor Hirotomo Nishihara and Professor Takashi Kyotani of the Institute of Multidisciplinary Research for Advanced Materials at Tohoku University. Graphene meso sponges have numerous pore walls, which are small hollow spheres made of carbon atoms. The pore walls are made of single-layer graphene. The pore walls are arranged three-dimensionally, with the internal spaces of adjacent pores interconnected in the length, width, and height directions, and adjacent pore walls are connected to each other. Graphene meso sponges are not only compressible and resilient like ordinary sponges, but also have numerous pore walls, which enable them to absorb water through capillary action. Furthermore, because they are made of carbon atoms, they have electrical conductivity similar to that of carbon black, making them suitable for use as electrodes. In variant example 1, a sponge body 29 made of Granphene meso sponge, an example of a conductive sponge, is used to perform the functions of the planar electrode 22, water-retaining sheet 25, and fiber rod 27 that were omitted from the carbon dioxide reduction device in the above-mentioned embodiment.

[0041] The sponge body 29 has a dish portion 29A and a pillar portion 29B. Although not limited to this, the dish portion 29A and the pillar portion 29B are integral with each other. Although not limited to this, the dish portion 29A and the pillar portion 29B are both formed as bodies of revolution symmetrical about the axis of the container 10. Dish portion 29A performs the functions of sheet electrode 22 and water retention sheet 25 provided in the carbon dioxide reduction device in the above-described embodiment. Pillar portion 29B performs the functions of fiber rod 27 provided in the carbon dioxide reduction device in the above-described embodiment. Dish portion 29A and pillar portion 29B may be integrated, or may be separate bodies, provided that the upper end of pillar portion 29B is in close contact with the lower end of dish portion 29A. The lower surface of the dish portion 29A is a curved surface that generally follows the upper surface of the electrode support member 24, and the upper surface is machined to form a concave surface. The upper surface of the dish portion 29A corresponds to the electrode surface 22A. The concave surface on the upper surface of the dish portion 29A corresponds to the concave surface on the electrode surface 22A of the planar electrode 22 in the above-described embodiment. The concave surface on the upper surface of the dish portion 29A is recessed relative to the first cathode 21A. Furthermore, as described in the description of the above-described embodiment, the surface of the concave surface may coincide with the outer surface of a virtual sphere centered on the lower end of the first cathode 21A. The column portion 29B is rod-shaped, and in this embodiment, is cylindrical, although not limited thereto. In this embodiment, the upper end of the column portion 29B extends to the underside of the dish portion 29A, and the lower end thereof reaches the bottom of the container 10, although not limited thereto. Therefore, a certain range on the lower end side of the column portion 29B is submerged in the aqueous solution 50 when the aqueous solution 50 is stored at the bottom of the container 10.

[0042] The method of use and operation of the carbon dioxide reducing device in Modification 1 is the same as the method of use and operation of the carbon dioxide reducing device according to the above-described embodiment. The aqueous solution 50 is poured into the container 10. Then, the lower end side of the columnar portions 29B of the sponge body 29 is immersed in the aqueous solution 50. Then, due to capillary action, the columnar portions 29B of the sponge body 29 suck up the aqueous solution 50 from the lower end side. The aqueous solution 50 flows up the columnar portion 29B and reaches the dish portion 29A from the top end of the columnar portion 29B. The aqueous solution 50 then seeps out onto the upper surface of the dish portion 29A, i.e., onto the electrode surface 22A. As a result, a layer of the aqueous solution 50 spreads over the electrode surface 22A of the dish portion 29A in a manner proportional to the size of the dish portion 29A. It is clear that the columnar portion 29B of the sponge body 29 can be replaced with the fiber rod 27 described in the above embodiment, and that doing so also makes it possible to supply the aqueous solution 50 to the dish portion 29A of the sponge body 29. Conversely, it is also clear that the fiber rod 27 of the above embodiment can be replaced with the columnar portion 29B of the sponge body 29. Dish portion 29A is a part of sponge body 29 made of conductive sponge, and electrode surface 22A is the upper surface of dish portion 29A. Because the conductive sponge itself has water retention properties, it is possible to allow layered aqueous solution 50 to spread to a certain extent on electrode surface 22A without placing water retention sheet 25 on dish portion 29A. The aqueous solution 50 is continuously supplied to the electrode surface 22A of the dish portion 29A as described above as long as the aqueous solution 50 at the bottom of the container 10 does not run out.

[0043] After placing the carbon dioxide reduction device in an appropriate position in the room and the aqueous solution 50 spreading in a layer on the dish portion 29A of the sponge body 29, the user operates the operation switch 31 to input an ON input, which is an input to start the operation of the carbon dioxide reduction device. The subsequent steps are the same as those in the above embodiment.

[0044] Corona discharge occurs between the needle-like electrode 21 (more precisely, the first cathode 21A) and the dish portion 29A of the sponge body 29, and between the needle-like electrode 21 (more precisely, the second cathode 21B) and the cylindrical electrode 23, in which electrons fly through the air from the former to the latter. In the α range, β range, and γ range, the same phenomenon as that described in the above embodiment occurs. As a result, carbon dioxide is reduced and hydroxide ions (OH) - , chloride ion Cl - The release of ozone O3 into the room has the effect of sterilizing the air.

[0045] <Variation 2> A carbon dioxide reduction device according to the second modification will be described. The carbon dioxide reduction apparatus of the second modification is almost the same as the carbon dioxide reduction apparatus of the first embodiment. The difference is that in the first embodiment, the first cathode 21A is a single electrode that is part of the needle-like electrode 21A, but in the second modification, there are a plurality of first cathodes 21A.

[0046] In this embodiment, the first cathode 21A, which is a collection of needle-like electrodes, is configured as follows. As in the first embodiment, the first cathode 21A is a part of one needle-like electrode 21 that includes the first cathode 21A and the second cathode 21B. Furthermore, the needle-like electrode 21 is electrically connected to an electrode body including a number of needle-like electrodes, as will be described later. The electrode body 60 in this embodiment has an elongated, but in this embodiment rectangular, metal plate 61 having electrical conductivity, as shown in Figure 6(A) or (B), although this is not limited thereto. In the example shown in FIG. 6(A), the lower edge of the metal plate 61 is configured in a zigzag pattern. The sharp vertices 61A on the lower edge of the metal plate 61 are needle-like electrodes. Although not limited to this, in this embodiment there are 14 vertices 61A that function as needle-like electrodes, but the number of vertices 61A may be more or less than this. Note that although the vertices 61A of the metal plate 61 or a predetermined range including the vertices 61A are not so-called "needle-like," they are still included in the "needle-like electrode" as defined in this application if they are electrodes from which discharge occurs in an extremely narrow range that can be called a "point." In the example shown in Fig. 6(B), needles 62, which are also made of, for example, a metal and have electrical conductivity, are attached to the metal plate 61. The needles 62 are electrically connected to the metal plate 61 and are attached to the metal plate 61 by, for example, welding. The tip of each needle 62 (the lower tip in Fig. 6(B)) protrudes downward from the metal plate 61 by the same length. The portion of each needle 62 protruding downward from the metal plate 61 functions as a needle-shaped electrode. The metal plate 61 in Fig. 6(A) or (B) is wound from either end in the length direction into a roll. As a result, the apex 61A in the example of Fig. 6(A) or the tips of the needles 62 in the example of Fig. 6(B) are on the same plane. Fig. 6(C) shows a bottom view of an example of the electrode body 60 after being rolled. Point X in Fig. 6(C) indicates the location of the apex 61A in the example of Fig. 6(A) or the tips of the needles 62 in the example of Fig. 6(B), both of which function as (or are) needle-like electrodes. The electrode body 60 is electrically connected to the needle-like electrode 21. The needle-like electrode 21 and the electrode body 60 may be electrically connected directly or via another member. Although not limited to this in this embodiment, the electrode body 60 is arranged so that the needle-like electrode 21 is located in the space at the center of the rolled electrode body 60. One end of the metal plate 61 constituting the electrode body 60 in the longitudinal direction is electrically connected to some part of the needle-like electrode 21. As a result, the potential applied to the electrode body 60 is always the same as the potential applied to the needle-like electrode 21. It is of course possible to omit the needle-like electrode 21 or the first cathode 21A of the needle-like electrode 21 and connect the electrode body 60 to the pulse power supply 40 without the needle-like electrode 21. In this embodiment, one electrode body 60 is arranged in front of the electrode surface 22 with the tip of the portion corresponding to the needle-like electrode facing the electrode surface 22A of the planar electrode 22, but it is also possible to arrange multiple electrode bodies 60 in front of the electrode surface 22 with the tip of the portion corresponding to the needle-like electrode facing the electrode surface 22A. In this case, each of the multiple electrode bodies 60 is placed in a conductive state. Furthermore, without using the electrode body 60, it is also possible to arrange a plurality or a large number of first cathodes 21A in front of the electrode surface 22 with their tips facing the electrode surface 22A of the planar electrode 22. For example, an example of such a configuration is one in which, when viewed from a direction perpendicular to the electrode surface 22, a large number of first cathodes 21A positioned at equal distances from the electrode surface 22 are arranged in a grid pattern. Even in this case, the large number of first cathodes 21A are in a state of mutual conduction. In this embodiment, the tip of the first cathode 21A included in the needle-shaped electrode 21 and the vertex 61A in the example of Figure 6(A) included in the electrode body 60, or the tip of the needle 62 in the example of Figure 6(B), are made to be on the same plane, although this is not limited to this. For reference, an overall view of the carbon dioxide reduction device with the electrode assembly 60 attached is shown in Figure 7. The positioning in Figure 7 is the same as in Figure 1. In Figure 7, the electrode assembly 60 is shown in perspective with a two-dot chain line. The vertex 61 and needle 62 have been omitted for convenience of drawing.

[0047] The operation and usage of the carbon dioxide reducing apparatus of Modification 2 is basically the same as the operation and usage of the carbon dioxide reducing apparatus of the first embodiment. The difference is that, while in the first embodiment, corona discharge occurs between one first cathode 21A and any location on the electrode surface 22A of the planar electrode 22, in the second modification, corona discharge occurs virtually simultaneously between one first cathode 21A and the apex 61A in the example of FIG. 6(A) or the tip of the needle 62 in the example of FIG. 6(B) that functions as a needle-like electrode (or is a needle-like electrode) in the electrode body 60, and any location on the electrode surface 22A. By combining with the pulse power supply 40, the number of corona discharges that occur between the needle-like electrode 21 and the electrode body 60 and the electrode surface 22A of the planar electrode 22 becomes very large. Corona discharge causes the same phenomenon as described in the above-mentioned embodiments in the α range, β range, and γ range, but in the carbon dioxide reduction device of variant 2, the above-mentioned phenomenon occurring in the α range and β range occurs in a more accelerated state. This will further promote the reduction of carbon dioxide and hydroxide ions (OH) - , chloride ion Cl - This will also further enhance the effect of air sterilization by releasing ozone O3 into the room.

[0048] Second Embodiment A carbon dioxide reducing apparatus according to a second embodiment will be described. The biggest difference between the carbon dioxide reduction device according to the second embodiment and the carbon dioxide reduction device according to the first embodiment is that the planar electrode 22, which was arranged roughly horizontally in the first embodiment, is arranged roughly vertically, or the electrode surface 22A, which was roughly horizontal in the first embodiment, is roughly vertical in the second embodiment. Based on these differences, there are various structural differences between the carbon dioxide reducing apparatuses of the first and second embodiments.

[0049] FIG. 8 is a cross-sectional view showing a schematic structure of a carbon dioxide reducing apparatus according to the second embodiment. The carbon dioxide reducing device according to the second embodiment includes a container 10, similar to the first embodiment. The container 10 is airtight and watertight, and in this embodiment, has a vertically elongated square prism shape, although this is not limited thereto. The container 10 has the same intake port 11 and exhaust port 13 as in the first embodiment. However, the position of the intake port 11 in the second embodiment is different from that in the first embodiment. In the second embodiment, the intake port 11 is provided above the container 10, although this is not limited to this. Although not limited to this, a duct 12 is connected to the air intake 11. The duct 12 in the second embodiment can be configured substantially similar to the configuration of the duct 12 in the first embodiment, but the shape of the duct 12 differs from that of the first embodiment because the position of the air intake 11 and the position of the α range between the first cathode 21A and the planar electrode 22, which will be described later, differ between the second embodiment and the first embodiment. The duct 12 in the second embodiment extends obliquely from the intake port 11 toward a range α, which will be described later. The duct 12 is not essential in the second embodiment either, and therefore there is a certain degree of freedom in its configuration, as in the first embodiment.

[0050] In the first embodiment, three electrodes are provided in the container 10, but in the second embodiment, four electrodes are provided in the container 10. In the container 10 of the second embodiment, a first cathode 21A, a second cathode 21B, a planar electrode 22, and a cylindrical electrode 23 are provided. The cylindrical electrode 23 in the second embodiment is the same as that in the first embodiment. The first cathode 21A and the second cathode 21B in the second embodiment are obtained by dividing the single needle-like electrode 21 in the first embodiment into two. The first cathode 21A and the second cathode 21B are fixed in the container 10 by some means. In this embodiment, the first cathode 21A and the second cathode 21B are fixed to thin pillars 71 that stand upright from the bottom of the container 10, although this is not limited to this. The first cathode 21A is disposed in a horizontal direction, although this is not a limitation, and its tip faces the planar electrode 22 in this embodiment. The second cathode 21B is located in the same position as the second cathode 21B in the first embodiment, and its relative positional relationship with the cylindrical electrode 23 is also the same as in the first embodiment. The second cathode 21B is electrically connected to the first cathode 21A. For example, a conductor can be used to electrically connect the two. The sheet electrode 22 of the second embodiment may have a pot-like shape recessed toward the first cathode 21A, similar to the sheet electrode 22 of the first embodiment, but in this embodiment, it is flat, although not limited to this. The surface of the sheet electrode 22 facing the first cathode 21A is the electrode surface 22A. In this embodiment, although not limited to this, the electrode surface 22A is flat and vertical. Although not limited to this, the shape of the sheet electrode 22 in the second embodiment is rectangular. The top and bottom sides of the sheet electrode 22 in the second embodiment are horizontal. The axis of the first cathode 21A is on an axis that passes vertically through the center of the sheet electrode 22. As in the first embodiment, an aqueous solution, which will be described later, is spread in the form of a film on the surface of electrode surface 22A of sheet electrode 22 facing first cathode 21A. To assist this, electrode surface 22A in the second embodiment is covered with water retention sheet 25, as in the first embodiment. The material of water retention sheet 25 can be the same as in the first embodiment. Water retention sheet 25 covers, for example, the entire surface of electrode surface 22A, and its size and shape are the same as those of electrode surface 22A. Naturally, it is also possible to adopt the configuration described in the first embodiment, in which the sheet electrode 22 has water retention properties and the water retention sheet 25 is omitted. A diagram corresponding to FIG. 8 in this case is shown in FIG. 11.

[0051] An aqueous solution tank 72 for storing the aqueous solution 50 is provided on the outside of the container 10. The aqueous solution tank 72 is watertight and is configured to store the aqueous solution 50 therein. Although not limited to this, in this embodiment the aqueous solution tank 72 is configured integrally with the container 10. The aqueous solution tank 72 may also be provided inside the container 10, and its configuration and arrangement can be freely designed as long as it can store the aqueous solution 50 therein and can supply the aqueous solution 50 stored therein to the electrode surface 22A of the planar electrode 22. The aqueous solution tank 72 is provided with an inlet (not shown) that can be opened and closed freely. The aqueous solution tank 72 can be replenished with the aqueous solution 50 via the inlet. A hole 72A is formed in the side surface of the container 10, for example, near the bottom. A sponge 73 is provided in the hole 72A to guide the aqueous solution 50 stored in the aqueous solution tank 72 to the surface of the sheet electrode 22, or in this embodiment, to the water retention sheet 25 covering the sheet electrode 22. One end of the sponge 73 fits into the hole 72A in the aqueous solution tank 72, and the other end is connected to the upper edge of the rectangular sheet electrode 22 (more precisely, in this embodiment, the upper edge of the rectangular water retention sheet 25). The aqueous solution 50 absorbed by the sponge 73 through the hole 72A is gradually transported through the sponge 73 toward the water retention sheet 25 covering the sheet electrode 22. This movement of the aqueous solution 50 is achieved by gravity, so no external energy supply is required for the movement of the aqueous solution 50. To facilitate this, in this embodiment, the aqueous solution tank 72 is located higher than the sheet electrode 22. The sponge 73 is connected to the entire length of the upper side of the rectangular water retention sheet 25, or to multiple locations along the entire length of the upper side. Although not shown, the sponge 73 is shaped to make this possible. For example, even those skilled in the art will easily understand that if the sponge 73 is shaped so that its width increases from one end to the other, it will be possible to supply the aqueous solution 50 from the other end of the sponge 73 along the entire length of the upper side of the rectangular water retention sheet 25. When the aqueous solution 50 is supplied by the sponge 73 to the entire length of the upper side of the rectangular water retention sheet 25, the aqueous solution 50 gradually flows down within the water retention sheet 25 due to gravity. This ideally results in the aqueous solution 50 spreading over the entire surface of the water retention sheet 25. Even when the aqueous solution is supplied to multiple locations on the upper side of the water retention sheet 25, it is preferable to design the sponge 73 so that this also occurs. The sponge 73 can be replaced with another structure as long as it can supply the aqueous solution 50 stored in the aqueous solution tank 72 to the water retention sheet 25 or the electrode surface 22A. The sponge 73 can be replaced with, for example, the fiber rod 27 described in the first embodiment. Although not adopted in the second embodiment, it is also possible to arrange a structure similar to the rod support member 26 so as to surround the sponge 73. In this embodiment, the aqueous solution 50 is supplied to the water retention sheet 25 as described above, so there is no need for the holes described in the first embodiment to be present in the sheet electrode 22. The sheet electrode 22 in this embodiment is simply a metal plate.

[0052] In the second embodiment, as in the first embodiment, a control unit 30 connected to a pulse power supply 40 is provided at an appropriate position in the container 10. These components are the same as those in the first embodiment. The pulse power supply 40 applies a voltage between the first cathode 21A and the planar electrode 22 and between the second cathode 21B and the cylindrical electrode 23 so as to generate a corona discharge between the first cathode 21A and the planar electrode 22 and between the second cathode 21B and the cylindrical electrode 23.

[0053] The method of use and operation of the carbon dioxide reducing device according to the second embodiment described above will now be described. To use the carbon dioxide reduction device, the user places the carbon dioxide reduction device at an appropriate location in a room, for example. Around the time that the carbon dioxide reduction device is placed at an appropriate position in the room, the user stores the aqueous solution 50 in the aqueous solution tank 72 (FIG. 8). In this embodiment, the supply port is opened and the aqueous solution 50 is replenished into the aqueous solution tank 72. The aqueous solution 50 is the same in the first and second embodiments. The aqueous solution 50 in the aqueous solution tank 72 is carried by the sponge 73 along the entire length of the upper horizontal side of the rectangular water retention sheet 25. The aqueous solution 50 flows downward within the water retention sheet 25 from the upper side of the water retention sheet 25. As a result, the aqueous solution 50 permeates the entire water retention sheet 25. As a result, a film of aqueous solution 50 is present on electrode surface 22A, which is the surface of planar electrode 22 facing first cathode 21A, with a spread according to the thickness and size of water retention sheet 25. The supply of aqueous solution 50 to the water retention sheet 25 described above is carried out continuously as long as there is not a shortage of aqueous solution 50 in the aqueous solution tank 72. If the supply of aqueous solution 50 to the water retention sheet 25 becomes excessive and causes the aqueous solution 50 to drip from the water retention sheet 25, it is possible to provide a lid that can be opened and closed freely over hole 72A in the aqueous solution tank 72 so that hole 72A is open only between the time when the user inputs an ON input and the time when the user inputs an OFF input using switch 31.

[0054] After placing the carbon dioxide reduction device in an appropriate position indoors and allowing the aqueous solution 50 to permeate the entire water retention sheet 25, the user operates the operation switch 31 to input an ON input, which is an input for starting the operation of the carbon dioxide reduction device. The ON input is input to the computer 41 of the pulse power supply 40. In the second embodiment, the pulse power supply 40 generates a pulse voltage upon receiving an ON input. The pulse voltage is a pulsed high voltage, as in the first embodiment. The conditions for the voltage, frequency, etc. of the pulse voltage are the same between the first and second embodiments. The pulse power supply 40 applies a voltage between the first cathode 21A and the planar electrode 22, and between the second cathode 21B and the cylindrical electrode 23, so as to generate a corona discharge.

[0055] In this state, air enters the container 10 through the air intake 11 . The air passes through the duct 12 and reaches the area α between the tip of the first cathode 21 A and the electrode surface 22 A of the planar electrode 22 . The phenomenon occurring in the α range is the same between the first embodiment and the second embodiment. However, in the second embodiment, the downward flowing air is redirected by the ionic wind in the α range so that it flows toward the electrode surface 22A of the planar electrode 22. In the β range within the water retention sheet 25, the aqueous solution 50 present within the water retention sheet 25 is exposed to corona discharge. As a result, the same phenomenon that occurred in the β range in the first embodiment occurs in the β range in the second embodiment.

[0056] Transpired chloride ions Cl - The air containing ozone O, sodium carbonate NaCO, and sodium bicarbonate NaHCO moves upward and reaches the γ region between the second cathode 21B and the cylindrical electrode 23. Corona discharge also occurs in the γ region in the second embodiment, so the same phenomenon occurs as in the γ region in the first embodiment. Hydroxide ions (OH) are carried by the ion wind generated by the corona discharge. - , chloride ion Cl - The air containing water H2O, ozone O3, sodium carbonate Na2CO3, and sodium bicarbonate NaHCO3 is discharged to the outside of the container 10 through the exhaust port 13. This creates a negative pressure inside the container 10, which promotes the flow of air into the container 10 through the intake port 11.

[0057] In the second embodiment as well, the first cathode 21A can be combined with the electrode body 60 described in Modification 2, or the first cathode 21A can be replaced with the electrode body 60.

[0058] <Variation 3> A carbon dioxide reduction device according to the third modification will be described. The carbon dioxide reduction apparatus of the third modification is configured similarly to the carbon dioxide reduction apparatus of the second embodiment, except as otherwise noted. The carbon dioxide reduction device in Modification 3 differs from the carbon dioxide reduction device in the second embodiment in that the former does not have the aqueous solution tank 72 that was present in the latter. In this embodiment, as in the first embodiment, but not limited to this, a predetermined area within the container 10 from the bottom of the container 10 below the lower edge of the planar electrode 22 functions as the aqueous solution tank as referred to in the present application. In addition, since the aqueous solution tank 72 is omitted in Modification 3, the sponge 73 that was present in the carbon dioxide reduction device of the second embodiment and that guides the aqueous solution 50 from the aqueous solution tank 72 to the water retention sheet 25 is also omitted. Furthermore, in the carbon dioxide reduction device of Modification 3, the surface of sheet electrode 22 facing first cathode 21A is also covered with water retention sheet 25. Water retention sheet 25 in Modification 3 covers the entire electrode surface 22A of sheet electrode 22, and its lower end is submerged in aqueous solution 50. Although not limited to this, in this embodiment, sheet electrode 22 is rectangular, and its top and bottom sides are horizontal. Furthermore, although not limited to this, water retention sheet 25 is also rectangular. The top and bottom sides of water retention sheet 25 are horizontal and have the same length as the top and bottom sides of sheet electrode 22, and the lateral sides of water retention sheet 25 are longer than the top and bottom sides of sheet electrode 22. By fixing such a water-retaining sheet 25 to the planar electrode 22 so that its upper edge corresponds to the upper edge of the planar electrode 22, the water-retaining sheet 25 covers the entire surface of the electrode surface 22A of the planar electrode 22, and its lower end is submerged in the aqueous solution 50. Water retention sheet 25 is made of a material that has water retention and water absorption properties. As a result, water retention sheet 25 absorbs the aqueous solution 50 from its lower end submerged in the aqueous solution 50 and draws it upward. As a result, although it takes some time, water retention sheet 25 becomes completely saturated with aqueous solution 50. In other words, in Modification 3, the portion of water retention sheet 25 below the lower edge of sheet electrode 22 corresponds to the supply member or water absorption member referred to in this application. In order to provide the water retention sheet 25 with a certain level of water absorbency, although this is not a limitation, in Modification 3, cloth is selected as the material for the water retention sheet 25. The cloth that makes up the water retention sheet 25 may be woven fabric or nonwoven fabric. Although this is not a limitation, the water retention sheet 25 in this embodiment is made of nonwoven fabric. In addition, in Modification 3, it is also possible to adopt the configuration described in the first embodiment, in which the sheet electrode 22 has water retention properties and the water retention sheet 25 is omitted. In this case, the sheet electrode 22 can be given not only water retention properties but also water absorption properties. The sheet electrode 22 already described as having water retention properties also has water absorption properties. Figure 12 is a diagram corresponding to Figure 9 when the sheet electrode 22 has water retention properties and the water retention sheet 25 is omitted.

[0059] The method of use and operation of the carbon dioxide reducing apparatus of Modification 3 is the same as the method of use and operation of the carbon dioxide reducing apparatus of the second embodiment. The only difference between the two is the method of supplying the aqueous solution 50 to the water retention sheet 25. In the second embodiment, the aqueous solution 50 is supplied from the aqueous solution tank 72 to the water retention sheet 25 via the sponge 73, whereas in the third modification, the aqueous solution 50 stored at the bottom of the container 10 is sucked up from the portion of the water retention sheet 25 that is impregnated with the aqueous solution 50, and is supplied to the portion of the water retention sheet 25 that covers the electrode surface 22A of the planar electrode 22. As a result, in the α range, β range, and γ range in the carbon dioxide reduction apparatus of Modification 3, the same phenomenon occurs as in the α range, β range, and γ range in the carbon dioxide reduction apparatus of the second embodiment. [Explanation of symbols]

[0060] 10 containers 11 Air intake 12 Duct 13 Exhaust port 21 Needle electrode 21A 1st cathode 21B 2nd cathode 22 Planar electrode 23 Cylindrical electrode 24 Electrode support member 25 Water-retaining sheet 26 Rod support member 27 Fiber Rod 29 Sponge body 29A Dish section 29B Column section 40 Pulse Power Supply 41 Computer 46 High Voltage Power Supply 50 Aqueous solution 60 Electrode body 61 Metal plate 61A Vertex 62 needles 72 Aqueous solution tank 73 Sponge

Claims

1. an aqueous solution tank for storing an aqueous solution containing sodium ions; a container having an intake port which is an opening for introducing air into the container and an exhaust port which is an opening for discharging air from the container; a first cathode that is an electrode provided in the container; a first anode, which is an electrode provided in the container and to which a positive voltage relative to the first cathode is applied, which is paired with the first cathode and has an electrode surface that extends in a planar shape facing the first cathode; a power supply that applies a voltage of a potential that generates a corona discharge between the first cathode and the first anode; a supply member for supplying the aqueous solution from the aqueous solution tank to the electrode surface; A carbon dioxide reduction device comprising: The aqueous solution spread in a film form on the electrode surfaces is exposed to corona discharge generated between the first cathode and the first anode by application of a voltage by the power supply device. Carbon dioxide reduction devices.

2. The electrode surface is located below the first cathode, so that the corona discharge occurs in a vertical direction. The carbon dioxide reduction device according to claim 1.

3. a predetermined area below the first cathode and the first anode at the bottom of the container is used as the aqueous solution tank; The carbon dioxide reduction device according to claim 1 or 2.

4. The electrode surface is located laterally of the first cathode, so that the corona discharge occurs laterally. The carbon dioxide reduction device according to claim 1.

5. The aqueous solution tank is provided outside the container. The carbon dioxide reduction device according to claim 1 or 4.

6. the supply member has a water-absorbing member made of a water-absorbing material, one end of which is immersed in the aqueous solution tank and the other end of which extends to or near the electrode surface, and the aqueous solution in the aqueous solution tank absorbed by the water-absorbing member is supplied to the surface of the electrode surface. The carbon dioxide reduction device according to claim 1.

7. the first anode is plate-shaped, and the other end of the water-absorbing member extends to a back side of the electrode surface of the first anode, the first anode has holes for passing the aqueous solution supplied from the water-absorbing member; The carbon dioxide reduction device according to claim 6.

8. The holes are numerous. The carbon dioxide reduction device according to claim 7.

9. The water-absorbing member is composed of threads bundled together in the longitudinal direction or a sponge. The carbon dioxide reduction device according to claim 6.

10. The yarn is made of a water-absorbent material. The carbon dioxide reduction device according to claim 9.

11. The first cathode is a needle-like electrode protruding toward the electrode surface. The carbon dioxide reduction device according to claim 1.

12. The electrode surface is a concave surface recessed toward the first cathode. The carbon dioxide reduction device according to claim 1.

13. A water-retaining sheet is provided which covers the electrode surface and is made of a material having water-retaining properties. The carbon dioxide reduction device according to claim 1 or 7.

14. The needle electrode is a plurality of electrodes. The carbon dioxide reduction device according to claim 11.

15. The first anode is made of a conductive sponge, which is a sponge made of a conductive material, and the electrode surface is a surface of the conductive sponge. The carbon dioxide reduction device according to claim 1.

16. The supply member has a water-absorbing sponge made of a material having water absorption and conductivity, one end of which is immersed in the aqueous solution tank and the other end of which reaches the electrode surface or the vicinity thereof, and the aqueous solution in the aqueous solution tank absorbed by the water-absorbing sponge is supplied to the surface of the electrode surface; The conductive sponge and the water-absorbing sponge are integrally formed.

16. The carbon dioxide reduction device of claim 15.

17. The power supply device is configured to apply a pulsed high voltage of 30 Hz to 500 Hz between the first cathode and the first anode. The carbon dioxide reduction device according to claim 1.

18. a second anode that is an electrode provided in the vicinity of the exhaust port; a second cathode, which is an electrode paired with the second anode and positioned closer to the center of the container than the second anode, to which a negative voltage relative to the second anode is applied; It also has the power supply unit applies a voltage having a potential that generates a corona discharge between the second cathode and the second anode; An ionic wind generated by a corona discharge generated between the second cathode and the second anode is discharged from the exhaust port together with air accelerated by the ionic wind. The carbon dioxide reduction device according to claim 1.

19. The second anode is a cylindrical electrode with both ends open, and is fitted into the exhaust port.

19. The carbon dioxide reduction device of claim 18.

20. the first anode has water retention properties; The carbon dioxide reduction device according to claim 1.

21. As the aqueous solution, a sodium chlorite aqueous solution or a sodium chloride aqueous solution is used. The carbon dioxide reduction device according to claim 1.

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