Method for manufacturing carbon material

Abstract

To continuously generate a carbon material on an electrode in a method of producing the carbon material by electrolyzing an electrolyte including a carbon source.SOLUTION: A production method of a carbon material comprises a deposition step and a removal step. In the deposition step, a carbon material 20 derived from a carbon source and a eutectoid element 21 derived from a eutectoid element source are deposited in a cathode by applying a voltage between an anode 12 and the cathode 13 in an electrolyte 11 including the carbon source and the eutectoid element source. In the removal step, the eutectoid element is removed from a deposit including the carbon material and the eutectoid element by applying an energy to the eutectoid element deposited on the cathode.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for producing a carbon material.

Background Art

[0002] Patent Document 1 proposes a method for producing a carbon material in which a carbon material is formed on a cathode by electrolyzing an electrolytic solution containing a carbon source. In the method of Patent Document 1, the carbon material grows with a catalytic metal provided on the cathode as a nucleus.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the production method of Patent Document 1, when the generated carbon material covers the catalytic metal, the growth of the carbon material stops. For this reason, the carbon material cannot be continuously generated on the cathode.

[0005] In view of the above points, an object of the present invention is to continuously produce a carbon material on an electrode in a method for producing a carbon material by electrolyzing an electrolytic solution containing a carbon source.

Means for Solving the Problems

[0006] To achieve the above object, the invention according to claim 1 includes a precipitation step and a removal step. In the precipitation step, a voltage is applied between the anode (12) and the cathode (13) in an electrolytic solution (11) containing a carbon source and a eutectic element source, thereby precipitating a carbon material (20) derived from the carbon source and a eutectic element (21) derived from the eutectic element source on the cathode. In the removal step, energy is applied to the eutectic element precipitated on the cathode to remove the eutectic element from the precipitate containing the carbon material and the eutectic element.The removal process is performed after the precipitation process. When the voltage applied between the anode and the cathode in the precipitation process is a positive voltage, in the removal process, as energy, a reverse voltage with a direction opposite to the flow of the positive voltage and current is applied between the anode and the cathode.

[0007] As a result, even if the cathode is covered with a carbon material in the precipitation step, the carbon source contained in the electrolytic solution can contact the eutectic elements precipitated on the cathode. Therefore, the precipitation of the carbon material on the cathode can be continuously performed.

[0008] Further, by performing a removal step of applying energy to the eutectic elements of the cathode, the eutectic elements can be removed from the precipitate containing the carbon material and the eutectic elements, and only the carbon material can be obtained.

[0009] Note that the reference numerals in parentheses of the above components indicate the correspondence with the specific means described in the embodiments described later.

Brief Description of the Drawings

[0010]

Figure 1

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Modes for Carrying Out the Invention

[0011] Hereinafter, a plurality of embodiments for implementing the present invention will be described with reference to the drawings. In each embodiment, parts corresponding to those described in the preceding embodiment may be denoted by the same reference numerals and redundant descriptions may be omitted. When only a part of the configuration is described in each embodiment, other forms described previously can be applied to other parts of the configuration. Not only combinations of parts explicitly shown to be combinable in each embodiment, but also embodiments can be partially combined with each other as long as there is no problem with the combination.

[0012] (First Embodiment) As shown in FIG. 1, the carbon material production apparatus 1 includes an electrolytic cell 10, an electrolytic solution 11, an anode 12, a cathode 13, and a power source 14. The carbon material production apparatus 1 of the present embodiment produces a carbon material by electrolyzing an electrolytic solution 11 containing a carbon source to deposit the carbon material on the cathode 13. The carbon material deposited on the cathode 13 is amorphous carbon, graphene, carbon nanotubes, carbon nanowires, or the like. The carbon material does not necessarily have to be composed only of carbon atoms and may contain, for example, functional groups or metal atoms.

[0013] The electrolytic solution 11 is accommodated inside the electrolytic cell 10. As the electrolytic solution, an aqueous electrolyte solution, an ionic liquid, or the like can be used. The electrolytic solution 11 of the present embodiment contains a carbon source and a eutectic element source in advance. The carbon source and the eutectic element source may be contained in the electrolytic solution 11 in advance, or may be added to the electrolytic solution 11 later.

[0014] The carbon source contained in the electrolytic solution 11 serves as a raw material for the carbon material deposited on the cathode 13. The carbon source is a carbon-containing substance containing carbon atoms, and it is desirable to use an organic substance containing at least one of a methyl group, an ethyl group, or a carboxyl group.

[0015] As the carbon-containing substance, for example, alcohols such as methanol and ethanol, aliphatic nitriles such as ethyl nitrile and methyl nitrile, carboxylic acids such as formic acid and acetic acid, etc. can be used. Alternatively, gases such as methane, CO2, and CO may be used as the carbon-containing substance. These gases can be dissolved in the electrolytic solution 11 by, for example, bubbling. As the carbon source, one type of carbon-containing substance may be used, or a plurality of types of carbon-containing substances may be used.

[0016] The eutectic element source contained in the electrolytic solution 11 serves as a raw material for the eutectic element deposited on the cathode 13. The eutectic element is an element that is deposited simultaneously with the carbon material at the cathode 13. The eutectic element is directly deposited on the cathode 13 and is also deposited on the carbon material deposited on the cathode 13. The eutectic element has a function as a catalyst for the carbon deposition reaction and a function as a conductive material.

[0017] The eutectic element of the present embodiment is a metal, and metal ions are used as the eutectic element source. Metal ions can be obtained, for example, by dissolving a metal salt in the electrolytic solution.

[0018] As the metal constituting the eutectic element, for example, at least one of transition metals and rare earth metals can be used. Specifically, as the eutectic element, Cu, Ni, Pt, Pd, Rh, Fe, Co, Ti, Ru, which are metals having a function as a catalyst for the carbon deposition reaction, can be used. Also, in order to promote the deposition of the carbon material by a carbon source containing hydrogen atoms, it is desirable to use a metal (for example, Cu, Ni, Pt, Pd) having a high hydrogen attraction as the eutectic element. In the present embodiment, Cu is used as the eutectic element, and Cu 2+ is used as the eutectic element source.

[0019] The anode 12 and the cathode 13 are provided so as to be immersed in the electrolytic solution 11 inside the electrolytic cell 10. In the present embodiment, the anode 12 and the cathode 13 are plate-shaped, and the plate surfaces are arranged along the vertical direction.

[0020] The anode 12 can use any electrode material, and in this embodiment, a carbon electrode is used. The cathode 13 uses a conductive material having a function as a catalyst for the carbon deposition reaction. As the cathode 13, for example, a metal material can be used, and in this embodiment, Ni is used.

[0021] The power supply 14 applies a predetermined voltage between the anode 12 and the cathode 13. The power supply 14 of this embodiment is a DC power supply. The power supply 14 of this embodiment can change the direction of the current flowing between the anode 12 and the cathode 13. Specifically, it is possible to switch between a state where the positive electrode of the power supply 14 is connected to the anode 12 and the negative electrode of the power supply 14 is connected to the cathode 13, and a state where the negative electrode of the power supply 14 is connected to the anode 12 and the positive electrode of the power supply 14 is connected to the cathode 13.

[0022] With the positive electrode of the power supply 14 connected to the anode 12 and the negative electrode of the power supply 14 connected to the cathode 13, the voltage applied between the anode 12 and the cathode 13 is defined as the positive voltage. With the negative electrode of the power supply 14 connected to the anode 12 and the positive electrode of the power supply 14 connected to the cathode 13, the voltage applied between the anode 12 and the cathode 13 is defined as the reverse voltage. The positive voltage can be any waveform (e.g., sine wave, pulse wave, triangular wave, etc.), any frequency, and any voltage value (peak value). The voltage value can be, for example, several V to several 10 kV. The reverse voltage only needs to be higher than the oxidation-reduction potential of the eutectic element.

[0023] Next, a method for manufacturing a carbon material using the carbon material manufacturing apparatus 1 having the above configuration will be described with reference to FIGS. 2 and 3. The method for manufacturing a carbon material of this embodiment includes a deposition step of depositing a carbon material and a eutectic element on the cathode 13, and a removal step of removing the eutectic element from the deposit containing the carbon material and the eutectic element on the cathode 13. In the deposition step and the removal step, the direction of the current flowing between the cathode 13 and the power supply 14 is reversed.

[0024] First, the deposition process will be described with reference to FIG. 2. As shown in FIG. 2, in the deposition process, a positive voltage is applied between the anode 12 and the cathode 13 by the power source 14. By applying a positive voltage between the anode 12 and the cathode 13, electrolysis of the carbon source in the electrolyte 11 is performed. In the example shown in FIG. 2, the carbon source is methyl radical CH3 + and the carbon material 20 is deposited on the cathode 13.

[0025] In the cathode 13, the eutectic element 21 is deposited together with the carbon material 20. In this embodiment, Cu is deposited as the eutectic element 21. In addition to being directly deposited on the cathode 13, the eutectic element 21 is also deposited on the carbon material 20 deposited on the cathode 13. Therefore, even if the cathode 13 is covered with the carbon material 20, the carbon source in the electrolyte 11 can contact the eutectic element 21.

[0026] As described above, since the eutectic element 21 has a function as a catalyst for the carbon deposition reaction and a function as a conductive material, the carbon material 20 can be deposited on the eutectic element 21 deposited on the cathode 13. Therefore, in the cathode 13, the carbon material 20 is continuously deposited starting from the eutectic element 21.

[0027] Next, the removal process will be described with reference to FIG. 3. As shown in FIG. 3, in the removal process, a reverse voltage is applied between the anode 12 and the cathode 13 by the power source 14. When a reverse voltage is applied between the anode 12 and the cathode 13, energy is applied to the eutectic element 21 of the cathode 13. As a result, the eutectic element 21 deposited on the cathode 13 is ionized and dissolved in the electrolyte 11. As a result, the eutectic element 21 is removed from the precipitate containing the carbon material 20 and the eutectic element 21, and only the carbon material 20 remains on the cathode 13.

[0028] The carbon material 20 remaining on the cathode 13 can be peeled off from the cathode 13 using a mechanical method. Also, in the removal process, when a part of the metal material constituting the cathode 13 is dissolved in the electrolyte 11, the carbon material 20 can be easily peeled off from the cathode 13.

[0029] According to the present embodiment described above, in addition to the carbon source, the electrolytic solution 11 contains a eutectic element source. Therefore, by applying a positive voltage between the anode 12 and the cathode 13 in the deposition step, the eutectic element 21 can be deposited on the cathode 13 simultaneously with the carbon material 20. As a result, the carbon source contained in the electrolytic solution 11 can contact the eutectic element 21 deposited on the cathode 13, and the deposition of the carbon material 20 on the cathode 13 can be continuously performed.

[0030] Further, in the present embodiment, a removal step of applying a reverse voltage between the anode 12 and the cathode 13 is performed after the deposition step. As a result, in the removal step, the eutectic element 21 can be removed from the deposit on the cathode 13, and only the carbon material 20 can be obtained.

[0031] (Second Embodiment) Next, a second embodiment of the present invention will be described. Hereinafter, only the parts different from the first embodiment will be described.

[0032] As shown in FIG. 4, in the second embodiment, the electrolytic solution 11 does not contain a eutectic element source in advance, and the anode 12 contains a metal material constituting the eutectic element 21. In the example shown in FIG. 4, the anode 12 contains Cu.

[0033] In the deposition step of the second embodiment, the metal material of the anode 12 is ionized and dissolved in the electrolytic solution 11 to become a eutectic element source. In the example shown in FIG. 4, Cu of the anode 12 becomes Cu 2+ and dissolves in the electrolytic solution 11.

[0034] At the cathode 13, together with the carbon material 20, the eutectic element 21 derived from the eutectic element source dissolved from the anode 12 is deposited. As a result, even if the cathode 13 is covered with the carbon material 20, the carbon source in the electrolytic solution 11 can contact the eutectic element 21, and the carbon material 20 can be deposited on the eutectic element 21. Therefore, at the cathode 13, the carbon material 20 is continuously deposited starting from the eutectic element 21.

[0035] In the second embodiment described above, the anode 12 containing the metal material constituting the eutectoid element 21 is used, and the metal ions dissolved from the anode 12 are used as the eutectoid element source. Thereby, the precipitation of the carbon material 20 on the cathode 13 can be continuously performed without previously including the eutectoid element source in the electrolytic solution 11.

[0036] (Third Embodiment) Next, a third embodiment of the present invention will be described. Hereinafter, only the parts different from the above embodiments will be described.

[0037] In this third embodiment, a metal organic compound is used as the carbon source and the eutectoid element source contained in the electrolytic solution 11. The organic matter contained in the metal organic compound serves as the carbon source, and the metal element contained in the metal organic compound serves as the eutectoid element source. In the example shown in FIG. 5, copper acetate ions (Cu(CH3COO) + ) are contained in the electrolytic solution 11.

[0038] In the precipitation step of this third embodiment, the metal organic compound is electrolyzed. At the cathode 13, the carbon material 20 derived from the organic matter contained in the metal organic compound is precipitated, and the eutectoid element 21 derived from the metal element contained in the metal organic compound is precipitated on the cathode 13. Thereby, even when the cathode 13 is covered with the carbon material 20, the carbon source in the electrolytic solution 11 can contact the eutectoid element 21, and the carbon material 20 can be precipitated on the eutectoid element 21. For this reason, at the cathode 13, the carbon material 20 is continuously precipitated starting from the eutectoid element 21.

[0039] In the third embodiment described above, a metal organic compound is used as the carbon source and the eutectoid element source. Even with such a configuration, the precipitation of the carbon material 20 on the cathode 13 can be continuously performed.

[0040] (Fourth Embodiment) Next, a fourth embodiment of the present invention will be described. Hereinafter, only the parts different from the above embodiments will be described.

[0041] In the fourth embodiment, similar to the third embodiment, a metal organic compound is used as the carbon source and the eutectic element source contained in the electrolytic solution 11. In the fourth embodiment, the electrolytic solution 11 contains only the organic matter constituting the organometallic compound, and the anode 12 contains the metal element constituting the metal organic compound. That is, in the fourth embodiment, the metal element constituting the metal organic compound is supplied from the anode 12. In the example shown in FIG. 6, the anode 12 contains Cu, and the electrolytic solution contains acetic acid.

[0042] In the deposition step of the fourth embodiment, the metal material of the anode 12 is ionized and dissolved in the electrolytic solution 11, and combines with the organic matter contained in the electrolytic solution 11 to form a metal organic compound.

[0043] In the deposition step, the metal organic compound is electrolyzed. At the cathode 13, the carbon material 20 derived from the organic matter contained in the metal organic compound is deposited, and the eutectic element 21 derived from the metal element contained in the metal organic compound is deposited on the cathode 13. As a result, at the cathode 13, the carbon material 20 is continuously deposited starting from the eutectic element 21.

[0044] In the fourth embodiment described above, the anode 12 contains the metal element constituting the metal organic compound. Even with such a configuration, the same effects as those of the third embodiment can be obtained.

[0045] (Fifth Embodiment) Next, a fifth embodiment of the present invention will be described. Hereinafter, only the parts different from the above embodiments will be described.

[0046] In the fifth embodiment, the anode 12, the cathode 13, and the power source 14 of the above embodiments are respectively referred to as the first electrode 12, the second electrode 13, and the first power source 14.

[0047] As shown in FIG. 7, the carbon material manufacturing apparatus 1 of the fifth embodiment is provided with a third electrode 15 and a second power source 16. The third electrode 15 is plate-shaped, and the plate surface is arranged along the bottom surface of the electrolytic cell 10.

[0048] The second power source 16 has its negative electrode connected to the first electrode 12 and its positive electrode connected to the third electrode 15. The second power source 16 applies a voltage between the first electrode 12 and the third electrode 15.

[0049] In the deposition process of the fifth embodiment, with the positive electrode of the first power source 14 connected to the first electrode 12 and the negative electrode of the first power source 14 connected to the second electrode 13 by the first power source 14, a positive voltage is applied between the first electrode 12 and the second electrode 13. As a result, carbon material 20 and eutectic element 21 are deposited on the second electrode 13.

[0050] The carbon material 20 and eutectic element 21 deposited on the second electrode 13 may peel off from the second electrode 13. The carbon material 20 and eutectic element 21 peeled off from the second electrode 13 are deposited on the third electrode 15 provided on the bottom surface of the electrolytic cell 10.

[0051] In the removal process of the fifth embodiment, with the negative electrode of the first power source 14 connected to the first electrode 12 and the positive electrode of the first power source 14 connected to the second electrode 13 by the first power source 14, a reverse voltage is applied between the first electrode 12 and the second electrode 13. As a result, the eutectic element 21 is removed from the deposit containing the carbon material 20 and eutectic element 21 on the second electrode 13.

[0052] Furthermore, in the removal process of the fifth embodiment, with the negative electrode of the second power source 16 connected to the first electrode 12 and the positive electrode of the second power source 16 connected to the third electrode 15, a voltage is applied between the first electrode 12 and the third electrode 15 by the second power source 16. As a result, the eutectic element 21 is removed from the deposit on the third electrode 15, and only the carbon material 20 remains. In the removal process, the application of the voltage by the first power source 14 and the application of the voltage by the second power source 16 may be performed simultaneously or at different timings.

[0053] In the fifth embodiment described above, the third electrode 15 is provided on the bottom surface of the electrolytic cell 10, and a voltage is applied between the second electrode 13 and the third electrode 15 by the second power source 16 in the removal step. Thereby, even when the carbon material 20 and the eutectic element 21 deposited on the second electrode 13 are peeled off, the eutectic element 21 can be removed from the carbon material 20 and the eutectic element 21 deposited on the bottom surface of the electrolytic cell 10, and only the carbon material 20 can be obtained.

[0054] (Other embodiments) The present invention is not limited to the above-described embodiments, and various modifications can be made as follows without departing from the spirit of the present invention. Also, the means disclosed in each of the above embodiments may be appropriately combined within the feasible range.

[0055] For example, in each of the above embodiments, in the removal step, a reverse voltage is applied between the anode 12 and the cathode 13 to remove the eutectic element 21 from the deposit on the cathode 13. However, the eutectic element 21 may be removed from the deposit on the cathode 13 by applying energy of a type different from the reverse voltage. Examples of energy of a type different from the reverse voltage include electromagnetic field energy or electromagnetic wave energy such as light energy, magnetic field energy, and electric field energy.

[0056] When removing the eutectic element 21 (for example, Cu) using light energy, light having the plasma frequency of Cu or the d-sp band transition frequency may be irradiated near the cathode 13 to resonate Cu. When removing the eutectic element 21 using magnetic field energy, a high-frequency magnetic field may be applied near the cathode 13. When removing the eutectic element 21 using electric field energy, a high-frequency electric field may be applied between the anode 12 and the cathode 13 or at a portion where the anode 12 and the cathode 13 are divided into two.

[0057] In addition, in each of the above embodiments, an example in which a metal is used as the eutectic 21 deposited together with the carbon material 20 at the cathode 13 has been described. However, inorganic functional groups such as H and OH may be used as the eutectic 21. Inorganic functional groups such as H and OH can bind to the carbon material 20 and serve as a starting point when the carbon raw material 20 newly deposits. The inorganic functional groups such as H and OH may be supplied from inorganic substances such as H2O, or may be supplied from organic substances containing inorganic functional groups such as H and OH.

[0058] In addition, in each of the above embodiments, the deposition step and the removal step are performed using the power source 14 composed of a DC power source. However, the deposition step and the removal step may be performed using an AC power source.

Explanation of Reference Numerals

[0059] 11 Electrolyte 12 Anode 13 Cathode 20 Carbon material 21 Eutectic element

Claims

1. By applying a voltage between an anode (12) and a cathode (13) in an electrolytic solution (11) containing a carbon source and a eutectic element source, a deposition step of depositing a carbon material (20) derived from the carbon source and a eutectic element (21) derived from the eutectic element source on the cathode; An energy application step of applying energy to the eutectic element deposited on the cathode to remove the eutectic element from the deposit containing the carbon material and the eutectic element; comprising: The removal step is performed after the deposition step, When the voltage applied between the anode and the cathode in the deposition step is a positive voltage, in the removal step, as the energy, a reverse voltage with a direction of current flow opposite to that of the positive voltage is applied between the anode and the cathode. A method for producing a carbon material.

2. In the removal step, electromagnetic field energy or electromagnetic wave energy is used as the energy. The method for producing a carbon material according to claim 1.

3. The eutectic element is a metal, and the anode contains the metal constituting the eutectic element. In the deposition step, the metal contained in the anode is ionized and dissolved in the electrolytic solution to serve as the eutectic element source. The method for producing a carbon material according to claim 1 or 2.

4. The metal is at least one of a transition metal and a rare earth metal. The method for producing a carbon material according to claim 3.

5. The metal is at least one of Cu, Ni, Pt, Pd, Rh, Fe, Co, Ti, Ru. The method for producing a carbon material according to claim 4.

6. The carbon source and the eutectic element source are derived from the same organometallic compound. The method for producing a carbon material according to any one of claims 1 to 5.

7. The carbon source and the eutectic element source are derived from the same organometallic compound, The eutectic element is a metal, The anode contains the metal constituting the organometallic compound, and the electrolytic solution contains the organic substance constituting the organometallic compound. The method for producing a carbon material according to any one of claims 1 to 5, wherein in the precipitation step, the metal contained in the anode is ionized and dissolved in the electrolytic solution, and binds to the organic substance to form the organometallic compound.

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