Catalyst, cathode and electrolysis device

Abstract

To provide a catalyst capable of improving Faraday efficiency of a C2 compound and / or C3 compound.SOLUTION: A catalyst 10 is used in the electrolytic reduction of carbon dioxide and / or carbon monoxide. The catalyst 10 comprises diamond-like carbon particles 11 with a plurality of copper particles 12 being supported on the surface thereof and portions of the surfaces of the diamond-like carbon particles 11 being coated with the copper particles 12.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a catalyst, a cathode and an electrolysis device for use in the electrolytic reduction of carbon dioxide and / or carbon monoxide. [Background technology]

[0002] Traditionally, efforts have been made to mitigate or reduce the impact of climate change, and research and development into reducing carbon dioxide emissions has been carried out to achieve this.

[0003] Patent Document 1 describes a steep interface CO2 electroreduction catalyst for converting CO2 to multi-carbon compounds. The steep interface CO2 electroreduction catalyst includes a porous gas diffusion layer having a gas contact side configured to contact CO2 gas and pass CO2 gas to the opposite reaction interface side, and a catalyst layer disposed on the reaction interface side of the porous gas diffusion layer, covering the reaction interface side of the porous gas diffusion layer, and having an electrolyte contact side configured to contact an aqueous electrolyte. The porous gas diffusion layer is composed of a hydrophobic material. The catalyst layer is hydrophilic so that the aqueous electrolyte passes through the catalyst layer to form a gas-liquid interface on the opposite reaction interface side of the catalyst layer, and is composed of one or more metals selected to convert CO2 to multi-carbon compounds under determined electroreduction conditions, and is thin enough to prevent diffusion restriction of CO2 in the aqueous electrolyte and to enhance selectivity of multi-carbon compounds. Here, the catalyst layer includes Cu. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018 / 232515 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the steep interface CO2 electroreduction catalyst described in Patent Document 1 has low faradaic efficiency for C2 compounds and / or C3 compounds.

[0006] An object of the present invention is to provide a catalyst capable of improving the faradaic efficiency of a C2 compound and / or a C3 compound. [Means for solving the problem]

[0007] (1) A catalyst for use in the electrolytic reduction of carbon dioxide and / or carbon monoxide, comprising copper particles supported on the surface of diamond-like carbon particles, and a portion of the surface of the diamond-like carbon particles being covered with the copper particles.

[0008] (2) The catalyst according to (1), wherein the coverage of the diamond-like carbon particles with the copper particles is 30% or more and 70% or less.

[0009] (3) The catalyst according to (1) or (2), wherein the diamond-like carbon particles have an average particle size of 5 nm or more and 50 nm or less.

[0010] (4) The catalyst according to any one of (1) to (3), wherein the copper particles have an average particle size of 0.5 nm or more and 1.2 nm or less.

[0011] (5) A cathode, comprising the catalyst according to any one of (1) to (4) supported on the surface of a gas diffusion layer.

[0012] (6) An electrolytic device comprising the cathode according to (5). Effect of the Invention

[0013] According to the present invention, it is possible to provide a catalyst capable of improving the faradaic efficiency of a C2 compound and / or a C3 compound. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a catalyst according to one embodiment of the present invention. [Diagram 2]FIG. 2 is a schematic cross-sectional view showing a cathode according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0016] FIG. 1 shows a catalyst according to one embodiment of the present invention.

[0017] The catalyst 10 is used for the electrolytic reduction of carbon dioxide and / or carbon monoxide. The catalyst 10 has copper particles 12 supported on the surface of diamond-like carbon particles 11, and the surface of the diamond-like carbon particles 11 is partially coated with the copper particles 12.

[0018] In the electrolytic reduction reaction of carbon dioxide, the number of electrons required to generate the C2 compound and / or the C3 compound is greater than the number of electrons required to generate the C1 compound, but in the catalyst 10, electrons are supplied to the group derived from carbon dioxide and / or carbon monoxide bonded to the surface of the copper particle 12 via the surface of the diamond-like carbon particle 11 that is not covered with the copper particle 12. As a result, a carbon-carbon bond is formed, and as a result, the faradaic efficiency of the C2 compound and / or the C3 compound is improved. On the other hand, when the diamond-like carbon particle 11 does not exist or when the entire surface of the diamond-like carbon particle 11 is covered with the copper particle 12, it becomes difficult to supply electrons to the group derived from carbon dioxide and / or carbon monoxide bonded to the surface of the copper particle 12. As a result, it becomes difficult to form a carbon-carbon bond, and as a result, the faradaic efficiency of the C2 compound and / or the C3 compound is reduced. In addition, water is easily electrolytically reduced, and the faradaic efficiency of hydrogen is improved.

[0019] Here, a specific example of the electrolytic reduction reaction of carbon dioxide to produce the C1 compound is shown below. CO2+2H + +2e - →CO+H2O CO2+2H ++2e - →HCOOH CO2+6H + +6e - →CH3OH+H2O CO2+8H + +8e - →CH4+2H2O

[0020] In addition, specific examples of the electrolytic reduction reaction of carbon dioxide to produce C2 compounds and / or C3 compounds are shown below. 2CO2+8H + +8e - →CH3COOH+2H2O 2CO2+12H + +12e - →CH3CH2OH+3H2O 2CO2+12H + +12e - →C2H4+4H2O 2CO2+14H + +14e - →C2H6+4H2O 3CO2+18H + +18e - →CH3CH2CH2OH+5H2O

[0021] Furthermore, the electrolytic reduction reaction of water is shown below. 2H2O+2e - →H2+2OH -

[0022] The coverage of the diamond-like carbon particles 11 by the copper particles 12 is preferably 30% or more and 70% or less, and more preferably 40% or more and 60% or less. When the coverage of the diamond-like carbon particles 11 by the copper particles 12 is 30% or more and 70% or less, the Faraday efficiency of the C2 compound and / or the C3 compound is improved. The coverage of the diamond-like carbon particles 11 by the copper particles 12 is measured by energy dispersive X-ray spectroscopy (TEM-EDX).

[0023] The average particle size of the diamond-like carbon particles 11 is preferably 5 nm or more and 50 nm or less, more preferably 5 nm or more and 10 nm or less. When the average particle size of the diamond-like carbon particles 11 is 5 nm or more and 50 nm or less, the Faraday efficiency of the C2 compound and / or the C3 compound is improved.

[0024] The average particle size of the copper particles 12 is preferably 0.5 nm or more and 1.2 nm or less, and more preferably 0.5 nm or more and 0.8 nm or less. When the average particle size of the copper particles 12 is 0.5 nm or more and 1.2 nm or less, the Faraday efficiency of the C2 compound and / or the C3 compound is improved.

[0025] The average particle size of the diamond-like carbon particles 11 and the copper particles 12 is determined, for example, as the average value of the Feret's diameters of 100 particles arbitrarily selected from a scanning electron microscope (SEM) image.

[0026] The catalyst 10 is manufactured, for example, as follows. First, an aqueous solution of copper acetate is prepared. At this time, the concentration of the aqueous solution of copper acetate is not particularly limited, but is, for example, 0.05M to 2M. Next, an aqueous dispersion of diamond-like carbon is prepared. At this time, the concentration of the aqueous dispersion of diamond-like carbon is not particularly limited, but is, for example, 4% by mass to 6% by mass, and the pH of the aqueous dispersion of diamond-like carbon is not particularly limited, but is, for example, 3 to 4. Next, the aqueous solution of copper acetate and the aqueous dispersion of diamond-like carbon are stirred, for example, using a magnetic stirrer. At this time, the mixing time is not particularly limited, but is, for example, 0.5 hours to 5 hours. Next, the diamond-like carbon particles with copper acetate particles supported on the surface are rinsed with distilled water, and then dried under an inert gas atmosphere, for example, at 500°C for 3 hours. At this time, the inert gas is not particularly limited, but examples thereof include helium gas and nitrogen gas. In addition, the catalyst 10 in which the copper particles 12 are supported on the surface of the diamond-like carbon particles 11 is obtained by annealing the catalyst 10 in a reducing gas atmosphere, for example, at a temperature of 500° C. or higher and 1050° C. or lower for 3 hours. The reducing gas is not particularly limited, but may be, for example, a mixed gas of argon gas and hydrogen gas.

[0027] An example of a commercially available diamond-like carbon product is Diamond nanopowder (manufactured by Sigma-Aldrich).

[0028] The catalyst 10 can be applied to a cathode for an electrolysis device for carbon dioxide and / or carbon monoxide, for example, by being disposed on a gas diffusion layer 21.

[0029] FIG. 2 shows a cathode according to one embodiment of the present invention.

[0030] The cathode 20 has a catalyst 10 supported on the surface of a gas diffusion layer 21 .

[0031] The gas diffusion layer 21 is not particularly limited as long as it is a porous layer that can transmit a raw material gas containing carbon dioxide and / or carbon monoxide, a gas produced by the electrolytic reduction of carbon dioxide and / or carbon monoxide, and hydrogen produced by the electrolytic reduction of water.

[0032] An example of a commercially available gas diffusion layer 21 is Sigracet 39 BB (manufactured by SGL Carbon).

[0033] The cathode 20 can be applied to a known carbon dioxide and / or carbon monoxide electrolysis device.

[0034] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and the above embodiment may be modified as appropriate within the scope of the spirit of the present invention. [Explanation of symbols]

[0035] 10. Catalyst 11 Diamond-like carbon particles 12 Copper particles 20 Cathode

Claims

1. A catalyst for use in the electrolytic reduction of carbon dioxide and / or carbon monoxide, comprising: Copper particles are supported on the surface of diamond-like carbon particles, A catalyst, wherein a portion of the surface of the diamond-like carbon particles is covered with the copper particles.

2. 2. The catalyst according to claim 1, wherein a coverage rate of said diamond-like carbon particles with said copper particles is 30% or more and 70% or less.

3. The catalyst according to claim 1 or 2, wherein the diamond-like carbon particles have an average particle size of 5 nm or more and 50 nm or less.

4. The catalyst according to claim 1 or 2, wherein the copper particles have an average particle size of 0.5 nm or more and 1.2 nm or less.

5. A cathode, comprising the catalyst according to claim 1 or 2 supported on the surface of a gas diffusion layer.

6. An electrolytic device comprising the cathode according to claim 5 .

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