Catalyst, cathode, and electrolysis device

Abstract

A catalyst for the electrolytic reduction of carbon dioxide and / or carbon monoxide, in which copper particles are supported on the surfaces of diamond-like carbon particles, and a part of the surfaces of the diamond-like carbon particles are covered by the copper particles.

Description

Technical Field

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

[0002] Efforts to mitigate climate change or reduce its impacts are continuing, and research and development related to reducing carbon dioxide emissions is being carried out to achieve this.

[0003] Patent document 1 describes a steep interface CO2 electroreduction catalyst for converting CO2 into multi-carbon compounds. The steep interface CO2 electroreduction catalyst includes: a porous gas diffusion layer having a gas contact side, the gas contact side being in contact with CO2 gas and being configured to allow CO2 gas to pass through a reaction interface side on the opposite side; and a catalyst layer, arranged 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 made 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 reaction interface side on the opposite side of the catalyst layer, and is composed of one or more metals selected to convert CO2 into multi-carbon compounds under certain electrolytic reduction conditions, and is thin enough to prevent diffusion restriction of CO2 in the aqueous electrolyte and improve the selectivity of multi-carbon compounds. Among them, the catalyst layer contains Cu.

[0004] [Prior Technical Literature]

[0005] (Patent Document)

[0006] Patent Document 1: International Publication No. 2018 / 232515 Summary of the invention

[0007] [Problems to be solved by the invention]

[0008] However, the Faraday efficiency of the C2 compound and / or C3 compound of the steep interface CO2 electro-reduction catalyst described in Patent Document 1 is low.

[0009] 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.

[0010] [Technical means to solve the problem]

[0011] (1) A catalyst for electrolytic reduction of carbon dioxide and / or carbon monoxide, comprising copper particles supported on the surface of diamond-like carbon particles, wherein a portion of the surface of the diamond-like carbon particles is covered with the copper particles.

[0012] (2) The catalyst according to (1), wherein a coverage rate of the diamond-like carbon particles with the copper particles is 30% to 70%.

[0013] (3) The catalyst according to (1) or (2), wherein the average particle size of the diamond-like carbon particles is 5 nm or more and 50 nm or less.

[0014] (4) The catalyst according to any one of (1) to (3), wherein the copper particles have an average particle size of 0.5 nm to 1.2 nm.

[0015] (5) A cathode, wherein the catalyst according to any one of (1) to (4) is supported on the surface of a gas diffusion layer.

[0016] (6) An electrolysis device comprising the cathode described in (5).

[0017] [Effects of the invention]

[0018] According to the present invention, it is possible to provide a catalyst that can improve the Faradaic efficiency of a C2 compound and / or a C3 compound. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic cross-sectional view showing a catalyst according to one embodiment of the present invention.

[0020] Figure 2 It is a schematic cross-sectional view showing a cathode according to one embodiment of the present invention. DETAILED DESCRIPTION

[0021] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0022] Figure 1 A catalyst according to one embodiment of the present invention is shown in FIG.

[0023] The catalyst 10 is used for electrolytic reduction of carbon dioxide and / or carbon monoxide. The catalyst 10 includes copper particles 12 supported on the surface of diamond-like carbon particles 11 , and a part of the surface of the diamond-like carbon particles 11 is covered with the copper particles 12 .

[0024] In the electrolytic reduction reaction of carbon dioxide, the number of electrons required for the generation of C2 compounds and / or C3 compounds is greater than the number of electrons required for the generation of C1 compounds, but in the catalyst 10, electrons are supplied to the groups from carbon dioxide and / or carbon monoxide bonded to the surface of the copper particles 12 via the surface of the diamond-like carbon particles 11 that are not coated with the copper particles 12. Therefore, a carbon-carbon bond is formed, and as a result, the Faraday efficiency of the C2 compound and / or C3 compound is improved. On the other hand, in the absence of diamond-like carbon particles 11 or when the entire surface of the diamond-like carbon particles 11 is coated with copper particles 12, it is difficult to supply electrons to the groups from carbon dioxide and / or carbon monoxide bonded to the surface of the copper particles 12. Therefore, it is difficult to form a carbon-carbon bond, and as a result, the Faraday efficiency of the C2 compound and / or C3 compound is reduced. In addition, water is easily electrolytically reduced, and the Faraday efficiency of hydrogen is improved.

[0025] Here, a specific example of the electrolytic reduction reaction of carbon dioxide generated from the C1 compound is shown below.

[0026] CO2+2H + +2e - →CO+H2O

[0027] CO2+2H + +2e - →HCOOH

[0028] CO2+6H + +6e - →CH3OH+H2O

[0029] CO2+8H + +8e - →CH4+2H2O

[0030] In addition, specific examples of the electrolytic reduction reaction of carbon dioxide generated by the C2 compound and / or the C3 compound are shown below.

[0031] 2CO2+8H + +8e - →CH3COOH+2H2O

[0032] 2CO2+12H + +12e - →CH3CH2OH+3H2O

[0033] 2CO2+12H + +12e - →C2H4+4H2O

[0034] 2CO2+14H + +14e - →C2H6+4H2O

[0035] 3CO2+18H + +18e - →CH3CH2CH2OH+5H2O

[0036] Furthermore, the electrolytic reduction reaction of water is shown below.

[0037] 2H2O+2e - →H2+2OH -

[0038] 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. If 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. In addition, the coverage of the diamond-like carbon particles 11 by the copper particles 12 is measured using energy dispersive X-ray spectroscopy (TEM-EDX).

[0039] The average particle size of the diamond-like carbon particles 11 is preferably 5 nm to 50 nm, more preferably 5 nm to 10 nm. If the average particle size of the diamond-like carbon particles 11 is 5 nm to 50 nm, the Faraday efficiency of the C2 compound and / or C3 compound is improved.

[0040] The average particle size of the copper particles 12 is preferably 0.5 nm to 1.2 nm, more preferably 0.5 nm to 0.8 nm. When the average particle size of the copper particles 12 is 0.5 nm to 1.2 nm, the Faraday efficiency of the C2 compound and / or C3 compound is improved.

[0041] The average particle diameter of the diamond-like carbon particles 11 and the copper particles 12 is obtained, for example, as the average value of Feret diameters of 100 particles randomly selected from a scanning electron microscope (SEM) image.

[0042] Catalyst 10 is manufactured, for example, in the following manner. 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, for example, it is greater than 0.05M and less than 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, for example, it is greater than 4% by mass and less than 6% by mass, and the pH of the aqueous dispersion of diamond-like carbon is not particularly limited, for example, it is greater than 3 and less than 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, for example, it is greater than 0.5 hours and less than 5 hours. Next, rinse with distilled water to allow the diamond-like carbon particles with copper acetate particles on the surface to settle, and then dry them at, for example, 500°C for 3 hours in an inert gas atmosphere. At this time, the inert gas is not particularly limited, and for example, helium and nitrogen can be listed. 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 at a temperature of 500°C to 1050°C for 3 hours in a reducing gas atmosphere. The reducing gas is not particularly limited, and an example thereof is a mixed gas of argon and hydrogen.

[0043] Examples of commercially available products of diamond-like carbon include Diamond nanopowder (manufactured by Sigma-Aldrich).

[0044] Furthermore, the catalyst 10 can be applied to a cathode for an electrolysis device of carbon dioxide and / or carbon monoxide by being arranged on the gas diffusion layer 21, for example.

[0045] Figure 2 Detailed Description of the Invention A cathode according to one embodiment of the present invention is shown in FIG.

[0046] In the cathode 20 , the catalyst 10 is supported on the surface of the gas diffusion layer 21 .

[0047] The gas diffusion layer 21 is not particularly limited as long as it is a porous layer that can pass a raw material gas containing carbon dioxide and / or carbon monoxide, a gas generated by electrolytic reduction of carbon dioxide and / or carbon monoxide, and hydrogen generated by electrolytic reduction of water.

[0048] As a commercially available product of the gas diffusion layer 21, for example, Sigracet 39BB (made of SGL carbon) can be cited.

[0049] Furthermore, the cathode 20 can be applied to a known electrolysis device for carbon dioxide and / or carbon monoxide.

[0050] As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, and the said embodiment can be modified suitably within the range of the summary of this invention.

[0051] Reference numerals

[0052] 10 Catalyst

[0053] 11 Diamond-like carbon particles

[0054] 12 Copper particles

[0055] 20 cathode

Claims

1. A catalyst for the electrolytic reduction of carbon dioxide and / or carbon monoxide, Copper particles are loaded on the surface of diamond-like carbon particles. A portion of the surface of the diamond-like carbon particle is covered with the copper particle.

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

3. The catalyst according to claim 1 or 2, wherein The average particle size of the diamond-like carbon particles is greater than or equal to 5 nm and less than or equal to 50 nm.

4. The catalyst according to claim 1 or 2, wherein The average particle diameter of the copper particles is not less than 0.5 nm and not more than 1.2 nm.

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

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