POROUS Cu MEMBER

Abstract

Provided is a porous Cu member which comprises: a member main body (11) that is formed of Cu or a Cu alloy and has a porous structure; and a nano-Cu structure layer (16) that is formed on at least a part of the surface of the member main body (11). The member main body (11) has a porosity in the range of 38% to 95% inclusive and a thickness in the range of 0.1 mm to 1.0 mm inclusive. The nano-Cu structure layer (16) is configured as a layer by laminating Cu particles, which have an average length of 20 µm to 1 nm, on the surface.

Description

Cu porous member

[0001] The present invention relates to a Cu porous member made of Cu or a Cu alloy, and in particular to a Cu porous member suitable as an electrode for carbon dioxide reduction by a co-electrolysis method. This application claims priority based on Japanese Patent Application No. 2023-211354, filed on December 14, 2023, the contents of which are incorporated herein by reference.

[0002] With global warming accelerating, CO in the atmosphere ２ Reducing greenhouse gases (GHGs), such as carbon dioxide (CO), is a global challenge. In recent years, the development of carbon dioxide capture and utilization (CCU) technology, which uses atmospheric carbon dioxide as a raw material to produce useful chemical products, has been accelerating. Carbon dioxide has the highest oxidation state of carbon, +4, and is a very stable compound with a standard Gibbs energy of formation of approximately 400 kJ / mol. Converting carbon dioxide into useful chemical products requires the reduction of carbon using a large amount of energy. There is a need for the development of technology that can reduce carbon dioxide energy efficiently.

[0003] In recent years, attention has been drawn to a co-electrolysis method using an electrolysis cell made of a polymeric ion exchange membrane (see, for example, Patent Documents 1 and 2). The co-electrolysis method is a technique in which electrolysis by oxidation reaction at the anode and electrolysis by reduction reaction at the cathode are simultaneously carried out in an electrochemical cell. For example, water is supplied to the anode and KHCO3 is supplied to the cathode. ３ Aqueous solution and CO ２ By using gas as a raw material, H ２ Using protons generated from the electrolysis of O, CO ２ When Ag is used as a catalyst, CO can be reduced with high faradaic efficiency. ２ CO gas can be obtained from

[0004] When Cu was used as a catalyst, CO was produced with high faradaic efficiency. ２Organic compounds with C2 or more carbon atoms (e.g., ethanol) can be obtained from the above. In recent years, it has been revealed that the faradaic efficiency of compounds with C2 or more carbon atoms can be improved depending on the oxidation number of Cu and the nanoscale geometric structure. By controlling the nanostructure, high-performance CO ２ A reduction catalyst has been proposed, in which carbon paper carrying nano-sized Cu particles is used as the electrode for the co-electrolysis method.

[0005] Japanese Unexamined Patent Publication No. 2022-049861 (A) Japanese Unexamined Patent Application No. 2022-040803 (A)

[0006] However, carbon paper carrying nano-sized Cu particles has a low mechanical strength and may be crushed in an electrolytic cell. ２ It is necessary to introduce gas and discharge liquids such as ethanol produced after the reaction outside the cell, but carbon paper has a relatively high pressure loss for gases and liquids, which reduces production efficiency.

[0007] The present invention has been made in light of the above circumstances, and provides a gas-transmitting device having sufficient strength and low pressure loss for gases and liquids, and capable of transmitting CO ２ The object of the present invention is to provide a Cu porous member capable of promoting a reduction reaction and efficiently producing organic compounds of C2 or more, such as ethanol.

[0008] In order to solve these problems and achieve the above-mentioned object, the Cu porous member of aspect 1 of the present invention comprises a member body made of Cu or a Cu alloy and having a porous structure, and a nano-Cu structure layer formed on at least a portion of the surface of the member body, wherein the member body has a porosity in the range of 38% to 95% and a thickness in the range of 0.1 mm to 1.0 mm, and the nano-Cu structure layer is characterized in that it is formed as a layer by stacking Cu particles having an average length of 20 μm to 1 nm on the surface.

[0009] According to the Cu porous member of the first aspect of the present invention, the member body is made of Cu or a Cu alloy and has a porous structure. The porosity is in the range of 38% to 95% and the thickness is in the range of 0.1 mm to 1.0 mm, which reduces the pressure loss of gases and liquids and allows stable flow of gases and liquids. Furthermore, the strength can be ensured, allowing stable use as an electrode. Furthermore, a nano-Cu structure layer is formed on at least a portion of the surface of the member body, which is composed of Cu particles having an average length of 20 μm to 1 nm stacked on the surface, and therefore, the Cu particles having an average length of 20 μm to 1 nm are used as a catalyst to efficiently produce CO. ２ It is possible to reduce the carbon dioxide to produce organic compounds with a carbon number of 2 or more, such as ethanol.

[0010] The Cu porous member of Aspect 2 of the present invention is characterized in that, in the Cu porous member of Aspect 1 of the present invention, the nano Cu structure layer is formed on one surface of the member body, and the coverage of the one surface of the member body with the nano Cu structure layer is 20% or more. According to the Cu porous member of Aspect 2 of the present invention, the catalytic action of Cu particles having an average length of 20 μm to 1 nm can be reliably achieved, and CO ２ This allows for more efficient reduction.

[0011] The Cu porous member of Aspect 3 of the present invention is characterized in that, in the Cu porous member of Aspect 1 or Aspect 2 of the present invention, the Cu particles having an average length of 20 μm to 1 nm that constitute the nano Cu structure layer have a dendritic or spherical shape. According to the Cu porous member of Aspect 3 of the present invention, since the Cu particles having an average length of 20 μm to 1 nm that constitute the nano Cu structure layer have a dendritic or spherical shape, the catalytic action of the nano Cu can be reliably achieved, and the CO ２ This allows for more efficient reduction.

[0012] The Cu porous member of aspect 4 of the present invention is characterized in that, in the Cu porous member of any one of aspects 1 to 3 of the present invention, the faradaic efficiency when used as an electrode in a co-electrolysis method to produce ethanol is 1.0% or more. According to the Cu porous member of aspect 4 of the present invention, the faradaic efficiency when used as an electrode in an electrolysis method to produce ethanol is 1.0% or more, so that CO ２ By reducing it, it becomes possible to efficiently produce ethanol.

[0013] According to the present invention, a gas separator having sufficient strength and low pressure loss for gases and liquids is provided. ２ It is possible to provide a Cu porous member that can promote a reduction reaction and efficiently produce organic compounds with a carbon number of 2 or more, such as ethanol.

[0014] FIG. 1 is an explanatory diagram showing an example of a Cu porous member according to an embodiment of the present invention. FIG. 2 is an enlarged explanatory diagram of the Cu porous member shown in FIG. 1. FIG. 3 is an explanatory diagram of Cu particles having an average length of 20 μm to 1 nm that constitute a nano Cu structure layer of a Cu porous member according to an embodiment of the present invention. FIG. 4 is an explanatory diagram of Cu particles having an average length of 20 μm to 1 nm that constitute a nano Cu structure layer of a Cu porous member according to an embodiment of the present invention. FIG. 5 is an explanatory diagram showing an example of an electrolysis cell using a Cu porous member according to an embodiment of the present invention.

[0015] Hereinafter, a Cu porous member according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0016] The Cu porous member 10 of this embodiment is used as a cathode electrode in an electrolytic cell used in a co-electrolysis method in which electrolysis is performed by an oxidation reaction at the anode and by a reduction reaction at the cathode.

[0017] 1 and 2, the Cu porous member 10 of this embodiment includes a member body 11 and a nano Cu structural layer 16 formed on at least a portion of the surface of the member body 11. In this embodiment, as shown in Fig. 1 and 2, the member body 11 is a sheet material, and the nano Cu structural layer 16 is formed on one main surface (one side) of the sheet material.

[0018] In this embodiment, the member body 11 made of Cu or a Cu alloy is a porous body as shown in Fig. 1, and includes a skeleton 12 having a three-dimensional network structure and pores 13 surrounded by the skeleton 12. The pores 13 surrounded by the skeleton 12 are interconnected and open to the outside of the member body 11.

[0019] The porosity P of the member body 11 is set to be in the range of 38% or more and 95% or less. By setting the porosity P of the member body 11 to be 38% or more, it is possible to allow gas and liquid to flow smoothly. On the other hand, by setting the porosity P of the member body 11 to be 95% or less, the strength of the member body 11 can be ensured and handling becomes easy. The porosity P of the member body 11 is preferably 45% or more, and more preferably 50% or more. The porosity P of the member body 11 is preferably 93% or less, and more preferably 90% or less.

[0020] The porosity P of the member body 11 is calculated by the following formula: P (%) = (1 - (W / (V x D Ｔ ))) × 100 W: Mass (g) of member body 11 V: Volume (cm ３ ) D Ｔ : true density (g / cm) of the metal material constituting the member body 11 ３ )

[0021] The thickness of the member body 11 is set to be within a range of 0.1 mm or more and 1.0 mm or less. Here, by setting the thickness of the porous structure member body 11 to 0.1 mm or more, it is possible for it to function sufficiently as a flow path for gases and liquids. On the other hand, by setting the thickness of the member body 11 to 1.0 mm or less, it becomes easy to handle without becoming excessively heavy. The thickness of the member body 11 is preferably 0.2 mm or more, and more preferably 0.3 mm or more. The thickness of the member body 11 is preferably 0.9 mm or less, and more preferably 0.8 mm or less.

[0022] In this embodiment, the Cu or Cu alloy constituting the porous member body 11 preferably has a Cu content of 80% by mass or more, and may contain elements other than Cu, such as Zn, Sn, P, Ca, Be, Co, Ni, Fe, Mn, Al, and Mg. By using Cu or a Cu alloy with a Cu content of 80% by mass or more, high conductivity can be ensured. The Cu content of the Cu or Cu alloy constituting the member body 11 is preferably 85% by mass or more, and more preferably 90% by mass or more.

[0023] In this embodiment, the nano Cu structure layer 16 is composed of Cu particles 18 having an average length of 20 μm to 1 nm, as shown in Figures 3A and 3B. Here, in this embodiment, the Cu particles 18 having an average length of 20 μm to 1 nm preferably have a dendritic shape as shown in Figure 3A or a spherical shape as shown in Figure 3B.

[0024] In this embodiment, the average length of the Cu particles 18 having an average length of 20 μm to 1 nm that constitute the nano Cu structure layer 16 is preferably within the range of 200 nm to 2000 nm. The average length L is the average length along which the longest straight line can be drawn within the Cu particle 18 when observing the cross section of one Cu particle 18. By setting the average length of the Cu particles 18 within the range of 200 nm to 2000 nm, the Cu particles 18 having an average length of 20 μm to 1 nm can efficiently act as a catalyst and reduce CO ２ The reduction reaction of Cu particles 18 having an average length of 20 μm to 1 nm is preferably 250 nm or more, and more preferably 300 nm or more. The average length of Cu particles 18 having an average length of 20 μm to 1 nm is more preferably 1900 nm or less, and even more preferably 1800 nm or less.

[0025] In this embodiment, it is preferable that the coverage of the nano Cu structural layer 16 on one surface of the member body 11 is 20% or more. By making the coverage of the nano Cu structural layer 16 on one surface of the member body 11 20% or more, Cu particles 18 having an average length of 20 μm to 1 nm act as a catalyst layer to efficiently generate CO ２ The reduction reaction proceeds. The coverage of the nano Cu structure layer 16 on one surface of the member body 11 is preferably 30% or more, and more preferably 40% or more. Although not particularly limited, the coverage of the nano Cu structure layer 16 on one surface of the member body 11 may be 90% or less, 75% or less, or 65% or less.

[0026] In this embodiment, the Faraday efficiency when used as an electrode for co-electrolysis to produce ethanol is preferably 1.0% or more. Although not particularly limited, the Faraday efficiency when used as an electrode for co-electrolysis to produce ethanol may be 1.3% or more, or may be 2.2% or more. Furthermore, although not particularly limited, the Faraday efficiency when used as an electrode for co-electrolysis to produce ethanol may be 100% or less, 99% or less, 98% or less, or 97% or less.

[0027] A schematic diagram of a co-electrolysis device using the Cu porous member 10 according to this embodiment is shown in Fig. 4. The co-electrolysis device according to this embodiment is a solid polymer type co-electrolysis device.

[0028] 4 , the co-electrolysis device 30 of this embodiment includes an electrolysis cell 31 including an anode 32 and a cathode 33 arranged opposite to each other, and an ion-permeable membrane 34 and a catalyst layer 35 arranged between the anode 32 and the cathode 33. Here, the anode 32, the ion-permeable membrane 34, and the catalyst layer 35 may be those used in conventional general solid polymer water electrolysis devices.

[0029] The cathode 33 is configured from the Cu porous member 10 of this embodiment, and includes a member body 11 made of Cu or a Cu alloy, and a nano Cu structure layer 16 formed on the surface of the member body 11. The member body 11 is also porous, and has a structure including a skeleton 12 with a three-dimensional network structure and pores 13 surrounded by the skeleton 12.

[0030] In the above-mentioned co-electrolysis device 30 (electrolysis cell 31), as shown in FIG. 4, water (H ２ O) is supplied to the cathode 33 side, and CO ２ Then, electricity is passed through the anode 32 and the cathode 33. Then, water is electrolyzed at the anode 32, and the generated oxygen (O ２ ) is discharged from the anode 32, and hydrogen (H ２ ) moves to the cathode 33. At the cathode 33, CO ２ is reduced to produce organic compounds of C2 or higher, such as ethanol. The produced organic compounds of C2 or higher, such as ethanol (C), are discharged to the outside of the electrolytic cell 31 through the pores 13 of the member body 11.

[0031] The Cu porous member 10 of this embodiment, configured as described above, has a member body 11 having a porous structure made of Cu or a Cu alloy, and the porosity P of this member body 11 is in the range of 38% to 95% and the thickness is in the range of 0.1 mm to 1.0 mm, so that the pressure loss of gases and liquids is low and gases and liquids can stably flow. Furthermore, strength can be ensured, allowing stable use as an electrode. Furthermore, a nano-Cu structure layer 16 made of Cu particles 18 having an average length of 20 μm to 1 nm is formed on at least a portion of the surface of the member body 11, so that CO can be efficiently produced using the nano-Cu as a catalyst. ２ It is possible to reduce the carbon dioxide to produce organic compounds of C2 or more, such as ethanol.

[0032] In this embodiment, when the nano Cu structure layer 16 is formed on one surface of the member body 11 and the coverage of the nano Cu structure layer 16 on one surface of the member body 11 is in the range of 20% to 100%, ２ and the like can be brought into sufficient contact with the Cu particles 18 having an average length of 20 μm to 1 nm, which serve as a catalyst, and CO ２ By promoting the reduction reaction, it becomes possible to produce organic compounds of C2 or more, such as ethanol, more efficiently.

[0033] In this embodiment, when the Cu particles 18 having an average length of 20 μm to 1 nm that constitute the nano Cu structure layer 16 are in a dendritic or spherical shape, the catalytic action of the nano Cu can be reliably achieved, and CO ２ By promoting the reduction reaction, it becomes possible to produce organic compounds of C2 or more, such as ethanol, more efficiently.

[0034] In this embodiment, when the average length of the Cu particles 18 having an average length of 20 μm to 1 nm that constitute the nano Cu structure layer 16 is set within the range of 200 nm to 2000 nm, ２ and the like can be brought into sufficient contact with the Cu particles 18 having an average length of 20 μm to 1 nm, which serve as a catalyst, and CO ２ By promoting the reduction reaction, it becomes possible to produce organic compounds of C2 or more, such as ethanol, more efficiently.

[0035] In this embodiment, when the electrode is used as a co-electrolysis electrode and the faradaic efficiency is 1.0% or more when ethanol is produced, CO ２ By reducing it, it becomes possible to efficiently produce ethanol.

[0036] Although the embodiment of the present invention has been described above, the present invention is not limited to this and can be modified as appropriate within the scope of the technical idea of ​​the invention.

[0037] The results of a confirmation experiment conducted to confirm the effects of the present invention are described below. First, the member bodies shown in Table 1 were prepared. The dimensions of each member body prepared were 10 mm wide x 10 mm long, and the thickness was as shown in Table 1. A nano Cu structure layer was formed on one surface of this member body as shown in Table 1. In the comparative example, a nano Cu structure layer was not formed.

[0038] Here, the nano Cu structure layer consisting of spherical Cu particles with an average length of 20 μm to 1 nm was fabricated as follows. A 10 cm diameter beaker was filled with a 0.05 mol / L copper pyrophosphate aqueous solution to prepare an electrodeposition solution. The member body was used as the working electrode, and a 25 mm x 10 mm Pt mesh was prepared as the counter electrode, and placed in the beaker so that the distance between the working electrode and counter electrode was 20 mm. A potentiostat (SP-50 manufactured by Bio-Logic) was used to adjust the current density to 2 to 30 mA / cm. ２ Under the condition, the charge amount per electrode area is 2 C / cm ２ The electrodeposition was carried out so that

[0039] Furthermore, a nano Cu structure layer consisting of dendrite-shaped Cu particles with an average length of 20 μm to 1 nm was fabricated as follows. A 10 cm diameter beaker was filled with a 0.05 mol / L copper pyrophosphate aqueous solution to prepare an electrodeposition solution. The member body was used as the working electrode, and a 25 mm x 10 mm Pt mesh was prepared as the counter electrode, and placed in the beaker so that the distance between the working electrode and counter electrode was 20 mm. A potentiostat (SP-50 manufactured by Bio-Logic) was used to set the current density at 50 mA / cm. ２ Under the above conditions, the charge amount per electrode area is 2 C / cm ２ The electrodeposition was carried out so that

[0040] A sample with a nano-Cu structure layer formed as described above was taken, and the surface structure was observed using a tabletop SEM (JCM-7000 manufactured by JEOL Ltd.). SEM images were taken at an acceleration voltage of 15 kV and a measurement magnification of 5,000x when observing spherical nano-sized Cu particles and 10,000x when measuring dendritic nano-sized Cu particles, and the coating thickness was measured using the measurement mode of the device. The obtained images were analyzed using analysis software (Fuji ImageJ). First, the image quality was adjusted using Gaussian Blur 3D Filter, with X sigma, Y sigma, and Z sigma set to 2.0. Then, binarization processing was performed using the following procedure. A graph was created from the Image → Adjust → Threshold items, with intensity on the vertical axis and brightness on the horizontal axis. The binarization process was performed by separating light and dark based on the light and dark positions of the peaks observed in the obtained spectrum (if multiple peaks occurred, the peak with the highest brightness was used). The particle boundaries were then separated from the obtained binarized image using the Watershed algorithm. The Analyze Particles process (setting values: size; 0-infinity, circularity; 0.00-1.00) was then performed to calculate the shape, average length, and coverage of the nano-sized Cu particles. The particle shape was determined using the Major (major axis) and Minor (minor axis) parameters that define ellipticity in the summary file obtained after the Analyze Particles analysis. A Major / Minor value greater than 1.7 was defined as a dendritic shape, and a particle shape less than 1.7 was defined as a particle shape. The average length was calculated using the Average Size (A) value in the summary file obtained after the analysis of Analyze Particles, and calculated using the formula: Average Length = 2 × √(A / π). The coverage was determined using the %Area value in the summary file obtained after the analysis of Analyze Particles.

[0041] The thickness of the member body was measured using a micrometer (manufactured by Mitutoyo).

[0042] The porosity of the member body was calculated from the mass and volume of the member body using the following formula: P (%) = (1 - (W / (V x D Ｔ ))) × 100 W: Mass (g) of member body 11 V: Volume (cm ３ ) D Ｔ : true density (g / cm) of the metal material constituting the member body 11 ３ )

[0043] The obtained Cu porous member was incorporated into an electrolysis cell as a cathode, and CO was produced by electrolysis. ２ The Faraday efficiency (ethanol production efficiency) of the ethanol produced from the ethanol-producing catalyst was measured. The evaluation results are shown in Table 1.

[0044] 1 cm with an anion exchange membrane ２ The obtained example was incorporated into the cathode of a 1000-mV electrochemical cell, and the current density was 100 mA / cm using a potentiogalvanostat (BioLogic HCP-803). ２ The flow between the electrodes was controlled so that the pure water used as the raw material was passed through the anode at a rate of 10 cc / min using a precision diaphragm pump (Takumina Smoothflow Pump Q Series). ２ The gas was controlled at 10 cc / min using a mass flow controller (manufactured by KOFLOC), and 0.1 M KHCO ３ The aqueous solution was flowed at a controlled rate of 1 cc / min using a precision diaphragm pump (FLOM KP21).

[0045] The post-reaction solution discharged from the cathode was separated from the gas, and the ethanol concentration in the resulting liquid was measured using a high-performance liquid chromatograph (JASCO Extrema). The ethanol concentration obtained using the high-performance liquid chromatograph was designated C, and the Faraday efficiency FE was calculated using the following formula: FE = n × C × F / (I × t × M) where, I (A): constant current applied to the electrode during electrolysis, t (s): electrolysis time, C (g / L): ethanol concentration measured using the high-performance liquid chromatograph, F (As / mol): Faraday constant, n: number of reaction electrons (CO ２→In the ethanol production reaction, 12) M (g / mol): molecular weight.

[0046]

[0047] In the comparative example, the ethanol production efficiency was low at 0.3%. ２ In contrast, in Examples 1 to 8 of the present invention, in which a nano Cu structure layer was formed on a member body made of Cu or a Cu alloy and having a porous structure, the ethanol production efficiency was high at 1.3% or more, and CO ２ It was possible to efficiently produce ethanol by reducing

[0048] From the results of the above confirmation experiments, it can be seen that the examples of the present invention have sufficient strength, low pressure loss for gases and liquids, and are suitable for CO ２ It was confirmed that it is possible to provide a Cu porous member that can promote a reduction reaction and efficiently produce organic compounds of C2 or more, such as ethanol.

[0049] According to the present invention, a gas separator having sufficient strength and low pressure loss for gases and liquids is provided. ２ It is possible to provide a Cu porous member that can promote a reduction reaction and efficiently produce organic compounds with a carbon number of 2 or more, such as ethanol.

[0050] 10 Cu porous member 16 Nano Cu structure layer

Claims

1. A Cu porous component comprising a component body made of Cu or a Cu alloy and having a porous structure, and a nano-Cu structure layer formed on at least a portion of the surface of the component body, wherein the component body has a porosity in the range of 38% to 95% and a thickness in the range of 0.1 mm to 1.0 mm, and the nano-Cu structure layer is formed as a layer by stacking Cu particles having an average length of 20 μm to 1 nm on the surface.

2. The Cu porous member described in claim 1, characterized in that the nano Cu structure layer is formed on one side of the member body, and the coverage rate of the nano Cu structure layer on the one side of the member body is 20% or more.

3. A Cu porous member according to claim 1 or 2, characterized in that the Cu particles constituting the nano Cu structure layer and having an average length of 20 μm to 1 nm are shaped as dendrites or spheres.

4. A Cu porous member according to claim 1 or 2, characterized in that the faradaic efficiency when used as an electrode in a co-electrolysis process to produce ethanol is 1.0% or more.

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