JP2023104814A - Formic acid producing apparatus - Google Patents

Abstract

To provide a formic acid producing apparatus with durability in which power loss is decreased by using a carbon material for an electrode.SOLUTION: A formic acid producing apparatus 1 for producing formic acid by reducing a carbon dioxide comprises: a first accommodation chamber 11 for accommodating an electrolyte 100; a second accommodation chamber 12 for accommodating the electrolyte 100 and the carbon dioxide; an anode electrode 21 arranged in the first accommodation chamber 11 in a state of contacting the electrolyte 100; a cathode electrode 22 arranged in the second accommodation chamber 12 in a state of contacting the electrolyte 100; and an external power source for applying voltages to the anode electrode 21 and the cathode electrode 22. The cathode electrode 22 is configured to have a porous carbon material with conductivity for carrying a carbon dioxide reduction catalyst and a pair of power collecting plates for sandwiching the carbon material. The pair of power collecting plates has an open area with multiple openings formed and a non-open area provided at a position where the open area is surrounded.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a formic acid generator, and more particularly to a formic acid generator having electrodes using a carbon material.

In recent years, attention has been paid to hydrogen energy and solar energy as alternative energy to fossil fuels such as coal and petroleum. Specifically, by supplying hydrogen obtained by decomposing formic acid to an external device, solar energy is effectively used to safely and efficiently supply hydrogen as an energy source.

For example, in Patent Document 1, an anode electrode placed in an electrolytic solution is arranged so that one side is in contact with the electrolytic solution and the other side is in contact with a CO ₂ -containing gas, and functions as a gas-liquid separation membrane and is porous. a conductive cathode electrode, and a power source for applying a voltage between the anode electrode and the cathode electrode, and the cathode electrode comprises a substrate made of a porous conductor and a Ru complex or Ru complex polymer as a reduction catalyst. A CO2 reduction reactor is described in which a _CO2 reduction reaction takes place between protons in the electrolyte and electrons from the cathode electrode and _CO2 from _the other side to synthesize an organic substance. . According to such a CO ₂ reduction reaction apparatus, a CO ₂ reduction reaction occurs at the cathode electrode by applying a predetermined voltage between the anode electrode and the cathode electrode. That is, a _CO2 reduction reaction occurs between the protons in the electrolyte, the electrons from the cathode electrode, and the _CO2 from the other side to synthesize formic acid.

Japanese Patent Application Laid-Open No. 2021-59760

By the way, in the CO ₂ reduction reactor described in Patent Document 1, carbon paper is used as the base material of the cathode electrode, and Ru complex or Ru complex polymer is supported on it, so that high formic acid generation can be achieved in a wide range of CO ₂ concentration. It is pointed out that selective performance can be obtained and formic acid can be produced with high Faradaic efficiency. However, when carbon materials are used for the electrodes, there are various problems.

Specifically, the electrical resistivity of a carbon material is about 100 to 1000 times higher than that of a metal material, even if it is the material itself. In composite materials such as Teflon resin, which are used for gas diffusion electrodes, the electrical resistivity is inevitably higher, and its value strongly depends on the manufacturing method. Such high resistivity causes ohmic loss when a large current flows.

Moreover, there is a problem that the carbon material is fragile as a material. Some uniform carbon materials such as carbon fiber are stronger than simple metals, but thin films based on composite carbon materials, such as those used in gas diffusion electrodes, are generally fragile and require careful handling. . A simple method has not been established for use in a large area that is practically important.

There are two methods for resolving these inconveniences. The first method is a method in which fine metal wires are formed on a glass substrate and a composite carbon material thin film is adhered thereon. However, this method requires printing fine lines on the glass substrate, which is complicated and not suitable for large-area devices. Moreover, since it is structurally impossible to introduce a gas diffusion layer, it cannot be diverted to a gas diffusion electrode.

The second method is to sandwich (or press) the thin film between metal current collectors. Although this method is widely used in fuel cells, its use is limited to cases where the following two points are satisfied: (1) the metal does not interfere with the desired reaction, and (2) the gas diffusion electrode itself has no rigidity. may In order to satisfy the condition (1), chemically inert materials such as titanium are used, but the problem of increased procurement costs and environmental load costs remains. Moreover, in a fuel cell, a composite carbon material thin film is generally sandwiched between a negative electrode, a separator, and a positive electrode, and the fuel reacts inside the thin film. It is filled. However, depending on the target chemical reaction, it is necessary to intentionally provide a gap between the negative electrode, the separator, and the positive electrode to hold the fragile composite carbon material thin film.

Accordingly, it is an object of the present invention to provide a durable formic acid generator that uses a carbon material as an electrode to reduce power loss.

One aspect of the present invention is a formic acid generator for reducing carbon dioxide to generate formic acid, comprising a first storage chamber containing an electrolyte and a second storage chamber containing the electrolyte and carbon dioxide. an anode electrode arranged in the first storage chamber in contact with the electrolyte; a cathode electrode arranged in the second storage chamber in contact with the electrolyte; the anode electrode and the cathode; an external power source for applying a voltage to the electrode, wherein the cathode electrode comprises a porous conductive carbon material for supporting a carbon dioxide reduction catalyst, and a pair of current collector plates sandwiching the carbon material. wherein the pair of current collector plates has an open area in which a plurality of openings are formed and a non-open area provided at a position surrounding the open area.

In the formic acid generator according to the present invention, the cathode electrode is arranged in the second storage chamber with one side in contact with the electrolytic solution and the other side in contact with the carbon dioxide, and the pair of current collector plates are arranged in the The carbon material may be formed of a resin material that is electrochemically inactive with respect to the electrolytic solution, and the carbon material may be arranged at a position overlapping the opening region.

In the formic acid generator according to the present invention, each of the pair of current collector plates has a conductive mesh member electrically connected to the carbon material in the opening region, and the mesh member includes a plurality of may have a honeycomb structure composed of openings in the

In the formic acid generator according to the present invention, the cathode electrode comprises a gas permeable membrane, a plurality of gaskets consisting of a first gasket, a second gasket and a third gasket, and a pair consisting of a first carbon material and a second carbon material. and a pair of current collector plates consisting of a first current collector plate and a second current collector plate, and the first gasket is provided between the first current collector plate and the second current collector plate and the second carbon material supported by the second gasket is arranged, and the third gasket is supported between the first carbon material and the second carbon material. The gas permeable membrane may also be disposed.

In the formic acid generator according to the present invention, the cathode electrode has a semipermeable membrane, a pair of frames consisting of a first frame and a second frame, a current collector, and a partition plate. The transparent membrane, the first frame, the current collector plate, the second frame, and the partition plate are arranged in this order. One through hole is formed, a first notch and a second notch are formed in the upper and lower sides, and the second frame has a pair of vertical portions and a pair of horizontal portions substantially perpendicular to the vertical portions. , the pair of vertical portions and the pair of horizontal portions form a second through hole, the pair of horizontal portions are respectively formed with an inlet and an outlet, and one of the pair of vertical portions has an air intake hole. An exhaust hole is formed in the other of the pair of vertical portions, and a pair of first and second openings are formed in the upper and lower sides of the current collector plate, and the semipermeable membrane and the pair of frames are formed. The electrolytic solution flows through the inlet, the first opening, the first notch, the first through hole, and the second notch in a state sealed by the body, the current collector plate, and the partition plate. , the second opening, and the outflow port in this order, and the carbon dioxide may pass through the intake hole, the second through hole, and the exhaust hole in this order.

ADVANTAGE OF THE INVENTION According to this invention, while reducing a power loss, it can provide the formic acid generator which has durability.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram showing the structural example of the formic acid production|generation apparatus which concerns on the 1st Embodiment of this invention. FIG. 4 is a schematic diagram showing a configuration example of a formic acid generator according to a second embodiment of the present invention; 1 is a perspective view of a carbon material and current collector plates in the first embodiment of the present invention; FIG. 1 is a plan view of a current collector plate according to a first embodiment of the present invention; FIG. FIG. 8 is an exploded perspective view of a cathode electrode of a formic acid generator according to a third embodiment of the present invention; FIG. 10 is a schematic diagram showing a configuration example of an electrolysis unit of a formic acid generator according to a fourth embodiment of the present invention;

First, a formic acid generator according to an embodiment of the present invention will be described. Note that common constituent elements will be described by attaching common reference numerals in the drawings. Further, the present invention is not limited to the following examples, and can be arbitrarily modified without departing from the gist of the present invention.

FIG. 1 is a schematic diagram showing a configuration example of a formic acid generator 1 according to an embodiment of the present invention. The formic acid generator 1 generates formic acid by artificial photosynthesis from water and atmospheric or exhaust carbon dioxide. The formic acid generator 1 includes a first storage chamber 11, a second storage chamber 12, an anode electrode 21 placed in the first storage chamber 11, a cathode electrode 22 placed in the second storage chamber 12, and an anode electrode. 21 and an external power source (not shown) for applying voltage to the cathode electrode 22 . The formic acid generator 1 may be used by being connected to, for example, a solar cell (not shown). In addition, it may replace with water and may use potassium hydrogencarbonate aqueous solution.

The electrolyte 100 is accommodated in the first accommodation chamber 11 , and the anode electrode 21 is arranged in contact with the electrolyte 100 . At the anode electrode 21, hydrogen ions and electrons are obtained by decomposing water. Between the first storage chamber 11 and the second storage chamber 12, a semipermeable membrane (Nafion membrane) 23 that selectively permeates hydrogen ions is arranged.

The second storage chamber 12 stores the electrolytic solution 100 and carbon dioxide. A cathode electrode 22 is arranged in the second housing chamber 12 in contact with the electrolytic solution 100 in which carbon dioxide is dissolved. At the cathode electrode 22, hydrogen ions and electrons obtained by decomposing water by the anode electrode 21 are used to convert carbon dioxide in the atmosphere into a carbon dioxide reduction catalyst (for example, a Ru complex, etc.) supported on the cathode electrode 22. and/or formic acid is produced by artificial photosynthesis from exhaust carbon dioxide.

FIG. 2 is a schematic diagram showing a configuration example of a formic acid generator 1 according to a second embodiment of the present invention. As shown in FIG. 2, the second storage chamber 12 is divided into a first storage space 12a in which the electrolytic solution 100 is stored and a second storage space 12b in which carbon dioxide is supplied. 100 and the other side may be in contact with carbon dioxide.

In the formic acid generator 1, formic acid is generated by artificial photosynthesis from water and atmospheric or exhaust carbon dioxide. The process of producing formic acid will be described below.

At the anode electrode 21, hydrogen ions and electrons are obtained by decomposing water. Anode electrode 21 and cathode electrode 22 are connected by a lead wire, and electrons generated at anode electrode 21 are sent to cathode electrode 22 . Hydrogen ions generated at the anode electrode 21 permeate the semipermeable membrane 23 and move to the cathode electrode 22 side. The cathode electrode 22 uses hydrogen ions and electrons obtained by decomposing water by the anode electrode 21 to produce formic acid from carbon dioxide in the atmosphere and/or exhaust carbon dioxide through artificial photosynthesis.

The formic acid generator 1 is used as a photochemical reaction device. It is preferable to employ a structure in which the cathode electrode 22 is irradiated with light during use. As a light source for irradiating the cathode electrode 22 with light, the sun, an artificial light source, or the like can be used.

In the formic acid generator 1, water is first decomposed at the anode electrode 21 to generate oxygen, hydrogen ions, and electrons as shown in the following formula (1).
2H ₂ O→O ₂ +4H ⁺ +4e ⁻ (1)

The anode electrode 21 is not particularly limited as long as it is a means for causing the above reaction, but for example, a water-splitting device such as a substrate supporting a photocatalyst is used.

At the cathode electrode 22, formic acid is produced from hydrogen ions, electrons, and carbon dioxide through a photoreaction (artificial photosynthesis) process (formula (2) below). At this time, hydrogen ions and electrons generated at the anode electrode 21 are consumed. Carbon dioxide can also be used as it is present in the atmosphere and/or in exhaust gases from other engines.
CO ₂ +2H ⁺ +2e ⁻ →HCOOH (2)

The cathode electrode 22 includes a carbon material 40 and a pair of current collector plates 50 sandwiching the carbon material 40 . FIG. 3 is a perspective view of the carbon material 40 and the current collector plate 50. FIG.

The carbon material 40 has porous conductivity for supporting the carbon dioxide reduction catalyst. Specifically, the carbon material 40 is a uniform thin film such as carbon fiber, and is a conductive material for reducing carbon dioxide. The thickness of the carbon material 40 is not particularly limited, but a thinner one is desirable.

A pair of current collector plates 50 have the same configuration. Each current collector plate 50 is a plate-like member formed in a rectangular shape when viewed from the front. The collector plate 50 is preferably large enough to cover the carbon material 40 . Each collector plate 50 is desirably made of a resin material that is electrochemically inactive to the electrolytic solution 100, such as polyetheretherketone (PEEK) and glass epoxy. Of the two surfaces of the current collector plate 50 , the surface on the carbon material 40 side is a first surface 51 , and the opposite surface is a second surface 52 . By sandwiching the carbon material 40 between two collector plates 50 made of an electrochemically inactive resin material, the cathode electrode 22 can ensure high rigidity as a structural body. Further, by increasing the area of the current collecting plate 50, even if the volume resistivity is high, the resistance of the electrode as a whole when the area is increased can be maintained at the resistance when the area is small. That is, it is possible to suppress ohmic loss and allow a large current to flow. The rigidity can be further increased by connecting the two current collecting plates 50 with screws, magnets, or the like.

Here, for example, assuming that the carbon thin film is formed in a circular shape, the two-point resistance Rs from the center of the carbon thin film having a diameter D (surface resistivity: ρs) to the outer diameter is It is calculated by the following formula (3) assuming that it is measured with a core rod (diameter d).

When the diameter D of the carbon thin film is 100 cm and the diameter d of the probe rod is 1 mm, the resistance value Rs is 1.10 ps. On the other hand, in this embodiment, the resistance value of the carbon thin film of any diameter is determined only by the size of each opening, and when the diameter of the circular opening is 1 cm, the resistance value Rs is reduced to 0.37 be done.

FIG. 4 is a diagram showing the configuration of the current collector plate 50. As shown in FIG. 4A shows the configuration of the first surface 51 of the current collector plate 50, and FIG. 4B shows the configuration of the second surface 52 of the current collector plate 50. FIG. As illustrated, the current collector plate 50 is provided with an open area 50a and a non-open area 50b. The open area 50a is formed in the central portion of the current collector plate 50, and the non-open area 50b is provided at a position surrounding the open area 50a. The open area 50a is where the carbon material 40 is placed. Considering that it is desirable to increase the contact area between the electrolytic solution 100 and carbon dioxide, the opening region 50a is desirably formed to have a larger area than the carbon material 40 .

The opening region 50a is composed of a plurality of openings, and the shape of each opening is not particularly limited and may be circular, polygonal, or the like. The ratio of the area occupied by the opening region 50a in the current collector plate 50 is not particularly limited, but the ratio occupied by the opening region 50a is preferably low.

As shown in FIG. 4A, a mesh member 61, a connection member 62 provided around the mesh member 61, and a plurality of electrodes 63 are provided on the first surface 51 side. The mesh-like member 61 is provided on the collector plate 50 at a location corresponding to the opening region 50a. Each electrode 63 is provided on both sides of the current collector plate 50 on the side of the first surface 51 and is connected to an external power supply. The connection member 62 is provided to connect the mesh member 61 and the plurality of electrodes 63 in the non-opening region 50b. The mesh member 61, the connection member 62, and the plurality of electrodes 63 may each have a thickness of a thin film, and are manufactured by plating, for example. By doing so, the amount of metal used can be significantly reduced, and procurement costs and environmental load costs can be reduced.

The mesh member 61 is arranged over the entire opening region 50a. Specifically, the mesh member 61 is a conductive wiring pattern provided around each of the plurality of openings forming the opening region 50a. Note that the mesh member 61 may not be provided around some of the openings. The carbon material 40 is arranged at the position where the mesh-like member 61 is provided, and the mesh-like member 61 and the carbon material 40 are electrically connected.

The mesh-like member 61 may have the same shape as the shape of the openings forming the opening region 50a. The shaped member 61 may also have a conductive honeycomb structure composed of a plurality of openings. The honeycomb structure of the opening region 50a can increase the strength of the current collector plate 50 . However, the mesh-like member 61 is not limited to the honeycomb structure as long as it has conductivity and has a plurality of openings.

In the state where the carbon material 40 is sandwiched between the pair of current collector plates 50 , the carbon material 40 is arranged in the current collector plate 50 at a position overlapping the opening region 50 a. Therefore, the carbon material 40 can efficiently come into contact with the electrolytic solution 100 and carbon dioxide. In addition, the entire carbon material 40 is electrically connected to the current collector plate 50 while being in contact with the mesh member 61, which is a conductive wiring pattern. Therefore, electricity can be efficiently supplied to the carbon material 40 . Therefore, the formic acid generator 1 can efficiently generate formic acid. A plurality of carbon materials 40 may be sandwiched between the pair of current collector plates 50 . Also, the carbon material 40 may have a range that does not contact the mesh member 61 in part.

As described above, the cathode electrode 22 includes a porous conductive carbon material 40 for supporting a carbon dioxide reduction catalyst, and a pair of current collector plates 50 sandwiching the carbon material 40. The pair of current collector plates 50 has an open area 50a in which a plurality of openings are formed and a non-open area 50b provided at a position surrounding the open area. Therefore, by using the carbon material 40 for the electrodes, the power loss can be reduced and the durability of the formic acid generator 1 can be ensured.

FIG. 5 is a diagram showing the configuration of the cathode electrode 22 according to the third embodiment of the invention. In the description of the third embodiment described below, the description of points common to the above-described embodiment will be omitted, and the differences from the first embodiment will be described.

As shown in FIG. 5, the cathode electrode 22 has a gas permeable membrane 70, a plurality of gaskets 80, a pair of carbon materials 140, and a pair of current collector plates 150. As shown in FIG. Specifically, the pair of carbon materials 140 is composed of a first carbon material 141 and a second carbon material 142 . The pair of current collectors 150 is composed of a first current collector 151 and a second current collector 152 . A gas permeable film 70 is disposed between the first carbon material 141 and the second carbon material 142, and the first carbon material 141 and the second carbon material 142 are connected to the first current collector 151 and the second current collector. 152. In this embodiment, when the X-axis direction and the Y-axis direction are horizontal directions, and the Z-axis direction is the vertical direction, the first current collector plate 151, the first carbon material 141, the gas permeable film 70, and the second carbon material 142 and the second collector plate 152 are arranged in this order in the X-axis direction.

The gas permeable membrane 70 has a main body portion 70a and a first protruding piece 70b integrally formed with the main body portion 70a. The body portion 70 a is formed in a rectangular shape in plan view and has approximately the same dimensions as the carbon material 140 . The gas-permeable membrane 70 is configured to allow gas such as carbon dioxide to permeate but liquid not to permeate. The gas-permeable membrane 70 is desirably made of a water-repellent porous material, more preferably made of porous Teflon.

The plurality of gaskets 80 has a first gasket 81 supporting the first carbon material 141, a second gasket 82 supporting the second carbon material 142, and a third gasket 83 supporting the gas permeable membrane 70. configured as follows. The first gasket 81 has a second projecting piece 81a on the same side as the first projecting piece 70b, and a first vent hole 81b is formed in the second projecting piece 81a.

The first collector plate 151 is provided with an opening region 151a and a non-opening region 151b at a position surrounding the opening region 151a. A second ventilation hole 153 is formed in the non-opening region 151b to allow passage of carbon dioxide. The location of the second ventilation hole 153 is not particularly limited as long as it is formed at a position overlapping the first ventilation hole 81b in the non-opening region 151b.

In the cathode electrode 22, a first gasket 81 having a first air hole 81b and a first collector plate 151 having a second air hole 153 are arranged on one side of the gas permeable membrane 70, The first protruding piece 70b, the first ventilation hole 81b and the second ventilation hole 153 are arranged at overlapping positions. That is, on one side of the gas-permeable membrane 70, the gasket 80 and the current collector plate 150 are formed with vent holes that allow gas to pass therethrough, and these vent holes are arranged so as to communicate with each other. Therefore, the supplied carbon dioxide reaches the gas-permeable membrane 70 via the second ventilation holes 153 and the first ventilation holes 81b. Generally, in the structure of a gas diffusion electrode, the cell wall plays a role of phase separation between gas and liquid, but due to this limitation, the mounting density is determined by the inner wall area of the cell. On the other hand, in the present embodiment, not only current but also gas (carbon dioxide) can be directly supplied to the carbon material 140, so a plurality of current collector plates 150 can be provided. Thereby, the mounting density of the cathode electrodes 22 can be increased.

FIG. 6 is an exploded perspective view of the electrolysis unit 200 of the formic acid generator according to the fourth embodiment. In addition, in the description of the fourth embodiment described below, the description of the points common to the above-described embodiment will be omitted, and the differences from the first embodiment will be described. The electrolytic unit 200 has a semipermeable membrane 23, a first frame 210, a collector plate 230, a second frame 220, and a partition plate 240 in this order. In this embodiment, the X-axis direction and the Y-axis direction are horizontal directions, and the Z-axis direction is the vertical direction.

The first frame 210 is formed in a rectangular shape in a plan view with a thin plate thickness, and has a first through hole 210a in the central portion. The first frame 210 is arranged between the semipermeable membrane 23 and the current collector 230 . A pair of first notch 211 and second notch 212 are vertically formed in the first frame 210 . In the following description, T is the thickness of the first frame 210 .

The collector plate 230 has a pair of first and second openings 231 and 232 formed vertically. The first opening 231 is formed at a position overlapping the first notch 211 in the X-axis direction, and the second opening 232 is formed at a position overlapping the second notch 212 in the X-axis direction. In the following description, W1 is the dimension (width) of the current collector plate 230 in the Y-axis direction.

The second frame 220 is formed in a rectangular shape in a plan view having a thickness in the X-axis direction. The second frame 220 includes a pair of vertical portions 220a extending in the Z-axis direction and a pair of horizontal portions 220b extending in the Y-axis direction. A second through hole 220c is formed by the pair of vertical portions 220a and the pair of horizontal portions 220b. One of the pair of vertical portions 220a is formed with an intake hole 223 communicating in the Y-axis direction, and the other is formed with an exhaust hole 224 communicating in the Y-axis direction. Of the pair of horizontal portions 220b, an inlet port 221 penetrating in the X-axis direction and Z-axis direction is formed in the upper portion, and an outlet port 222 penetrating in the X-axis direction and the Z-axis direction is formed in the lower portion. The inflow port 221 is formed at a position overlapping the first opening 231 in the X-axis direction, and the outflow port 222 is formed at a position overlapping the second opening 232 in the X-axis direction.

The electrolytic unit 200 is in a state in which the first frame 210 , the current collector plate 230 and the second frame 220 are sealed with the semipermeable membrane 23 and the partition plate 240 . That is, the first through hole 210a is sealed by the semipermeable film 23, the second through hole 220c is sealed by the partition plate 240, and the collector plate 230 is confined. In this state, the electrolytic solution passes through the inflow port 221, the first opening 231, the first notch 211, the first through hole 210a, the second notch 212, the second opening 232, and the outflow port 222 to enter the electrolysis unit. 200 is discharged to the outside. Also, gas such as carbon dioxide passes through the intake hole 223 , the second through hole 220 c and the exhaust hole 224 and is discharged to the outside of the electrolysis unit 200 .

Thus, by confining the current collector plate 230 in the electrolysis unit 200 having a simple configuration, the thickness T of the first frame 210 and the width W1 of the current collector plate 230 can be freely set. As the dimension of the thickness T of the first frame 210 is smaller, the power loss due to the solution resistance can be reduced. In addition, it can be expected that the smaller the volume of the electrolysis unit 200 is, the more the electrolytic solution containing the high-concentration product is discharged from the second storage chamber 12 .

Although one embodiment and examples of the present invention have been described in detail above, those skilled in the art will understand that many modifications are possible without substantially departing from the novel matters and effects of the present invention. would be easy to understand. Therefore, all such modifications are intended to be included in the scope of the present invention.

For example, a term described at least once in the specification or drawings together with a different, broader or synonymous term can be replaced with the different term anywhere in the specification or drawings. Also, the configuration of the formic acid generator is not limited to the one described in the embodiment and example of the present invention, and various modifications are possible.

1 Formic Acid Generator 11 First Storage Chamber 12 Second Storage Chamber 21 Anode Electrode 22 Cathode Electrode 40 Carbon Material 50 Current Collector 50a Opening Region 50b Non-Opening Region 61 Mesh Member 70 Gas Permeable membrane 81 First gasket 82 Second gasket 83 Third gasket 100 Electrolyte 141 First carbon material 142 Second carbon material 151 First current collector 152 Second current collector 210 First frame 210a First through hole 211 First notch 212 Second notch 220 Second frame 220a Vertical part 220b Horizontal part 220c Second through hole 221 Inlet 222 outflow port, 223 intake hole, 224 exhaust hole, 230 collector plate, 231 first opening, 232 second opening, 240 partition plate,

One aspect of the present invention is a formic acid generator for reducing carbon dioxide to generate formic acid, comprising a first storage chamber containing an electrolyte and a second storage chamber containing the electrolyte and carbon dioxide. an anode electrode arranged in the first storage chamber in contact with the electrolyte; a cathode electrode arranged in the second storage chamber in contact with the electrolyte; the anode electrode and the cathode; an external power supply for applying a voltage to the electrode, wherein the cathode electrode comprises a porous conductive carbon material for supporting a carbon dioxide reduction catalyst and a pair of identical aggregates sandwiching the carbon material. The pair of current collector plates has an open area in which a plurality of openings are formed and a non-open area provided at a position surrounding the open area , and the pair of current collector plates The plate is made of a resin material that is electrochemically inactive with respect to the electrolytic solution, and the carbon material is arranged at a position overlapping with the opening region.

In the formic acid generator according to the present invention, the cathode electrode may be arranged in the second storage chamber with one side in contact with the electrolytic solution and the other side in contact with the carbon dioxide.

Claims (5)

A formic acid generator for reducing carbon dioxide to produce formic acid,
a first storage chamber that stores an electrolytic solution;
a second storage chamber that stores the electrolytic solution and carbon dioxide;
an anode electrode arranged in the first storage chamber in contact with the electrolyte;
a cathode electrode arranged in the second housing chamber in contact with the electrolyte;
an external power supply for applying a voltage to the anode electrode and the cathode electrode;
The cathode electrode includes a porous conductive carbon material for supporting a carbon dioxide reduction catalyst and a pair of current collector plates sandwiching the carbon material,
A formic acid generating device, wherein the pair of current collector plates has an open area in which a plurality of openings are formed and a non-open area provided at a position surrounding the open area. The cathode electrode is arranged in the second storage chamber with one side in contact with the electrolytic solution and the other side in contact with the carbon dioxide,
The pair of current collector plates are made of a resin material that is electrochemically inactive with respect to the electrolytic solution,
2. The formic acid generator according to claim 1, wherein the carbon material is arranged at a position overlapping with the opening region. each of the pair of current collector plates has a conductive mesh member electrically connected to the carbon material in the opening region;
3. The formic acid generator according to claim 1, wherein said mesh member has a honeycomb structure composed of a plurality of openings. The cathode electrode includes a gas permeable membrane, a plurality of gaskets consisting of a first gasket, a second gasket and a third gasket, a pair of carbon materials consisting of a first carbon material and a second carbon material, and a first current collector. Having a pair of current collectors consisting of a plate and a second current collector,
the first carbon material supported by the first gasket and the second carbon material supported by the second gasket are arranged between the first current collector and the second current collector;
4. The gas permeable membrane supported by the third gasket is disposed between the first carbon material and the second carbon material, according to any one of claims 1 to 3. formic acid generator. The cathode electrode has a semipermeable membrane, a pair of frames consisting of a first frame and a second frame, a collector plate, and a partition plate, and the semipermeable membrane, the first frame, The current collector plate, the second frame, and the partition plate are arranged in this order,
The first frame is formed in a rectangular shape in plan view, has a first through hole formed in the center, and has a first notch and a second notch formed in the upper and lower sides,
The second frame has a pair of vertical portions and a pair of horizontal portions substantially perpendicular to the vertical portions, and a second through hole is formed by the pair of vertical portions and the pair of horizontal portions. An inlet and an outlet are formed in each of the horizontal portions, an intake hole is formed in one of the pair of vertical portions, and an exhaust hole is formed in the other of the pair of vertical portions,
A pair of first and second openings are formed in the upper and lower sides of the current collector plate,
In a state sealed by the semipermeable membrane, the pair of frames, the collector plate, and the partition plate, the electrolytic solution flows through the inlet, the first opening, the first notch, and the first opening. The carbon dioxide passes through the through hole, the second notch, the second opening, and the outflow port in this order, and the carbon dioxide passes through the intake hole, the second through hole, and the exhaust hole in this order. The formic acid generator according to any one of claims 1 to 3.