Manufacturing method of high crystalline carbon structure containing high content nitrogen

Abstract

The present invention relates to a method for manufacturing a highly crystalline carbon structure containing a high nitrogen content and a carbon structure manufactured therefrom. The method for manufacturing a highly crystalline carbon structure according to the present invention can produce a crystalline carbon structure that has excellent oxidation resistance, is rich in azo dye, and has a high specific surface area due to the addition of hydrogen and metal powder, and also has the effect of producing the carbon structure in the shortest possible time because the manufacturing is carried out at a low temperature. Therefore, the carbon structure produced by this method for manufacturing a highly crystalline carbon structure can be usefully used as an energy-related support or individual carbon material, such as for secondary batteries, fuel cells, and water electrolysis.

Description

Technology Field

[0001] The present invention relates to a method for manufacturing a highly crystalline carbon structure containing a high nitrogen content and a carbon structure manufactured therefrom. Background Technology

[0003] Mixed catalysts of precious metals and carbon supports are used in energy generation devices such as fuel cells and water electrolytic cells, but carbon supports have the disadvantage of inferior durability due to carbon corrosion (oxidation).

[0004] To address these issues, the development of highly graphite materials with excellent oxidation resistance is underway, but there are several drawbacks, such as the need to proceed with synthesis at high energy of over 1000°C during the synthesis process, limitations in improving specific surface area, and a low heteroatom doping rate.

[0005] Generally, carbon supports used in fuel cells and the like utilize g-C3N4 (Graphitic Carbon Nitride) or C3N5.

[0006] g-C3N4 was known to be synthesizable from urea in a 2006 study by Goettmann using Friedel-Crafts reactions, and is also synthesized using nitrogen-rich organic materials such as melamine, dicyandiamide, thiourea, and cyanamide as synthetic precursors. In addition, it has a hexagonal structure similar to graphite and has a band gap energy of 2.7 eV, so it is utilized as a photocatalyst.

[0007] In the case of C3N5, Gillan's study [indicated] 2,4,6-triazido-1,3,5-triazine (C3N 12 A manufacturing method is known that it can be synthesized through the thermal decomposition of ), and a three-step synthesis method using hydrazine was known in 2019. Prior art literature

[0009] Chem. Mater. 2000, 12, 3906-3912 The problem to be solved

[0010] The present invention aims to solve the aforementioned problem and other related problems.

[0011] One exemplary objective of the present invention is to provide a method for manufacturing a carbon structure comprising the following steps.

[0012] (a) A step of preparing a supersaturated solution by mixing a C3N5 precursor compound, distilled water, and hydrazine;

[0013] (b) a step of synthesizing C3N5 by heating the above supersaturated solution;

[0014] (c) A step of removing impurities from the synthesized C3N5;

[0015] (d) a step of mixing the C3N5 from which the above impurities have been removed with a metal and heating it; and

[0016] (e) A step of removing the metal to obtain crystalline carbon.

[0017] Another exemplary objective of the present invention is to provide a crystalline carbon structure produced by the above-described manufacturing method.

[0018] Another exemplary objective of the present invention is to provide an electrode catalyst comprising a crystalline carbon structure prepared by the above-described manufacturing method.

[0020] The technical problems to be solved according to the technical concept of the invention disclosed in this specification are not limited to those for solving the problems mentioned above, and other unmentioned problems will be clearly understood by a person skilled in the art from the description below. means of solving the problem

[0022] This is explained in detail as follows. Meanwhile, each description and embodiment disclosed in this application may be applied to each other description and embodiment. That is, all combinations of the various elements disclosed in this application fall within the scope of this application. Furthermore, the scope of this application should not be considered limited by the specific descriptions provided below.

[0023] As one embodiment for achieving the above objective, the present invention provides a method for manufacturing a carbon structure comprising the following steps.

[0024] (a) A step of preparing a supersaturated solution by mixing a C3N5 precursor compound, distilled water, and hydrazine;

[0025] (b) a step of synthesizing C3N5 by heating the above supersaturated solution;

[0026] (c) A step of removing impurities from the synthesized C3N5;

[0027] (d) a step of mixing the C3N5 from which the above impurities have been removed with a metal and heating it; and

[0028] (e) A step of removing the metal to obtain crystalline carbon.

[0029] The 'C3N5 precursor compound' of the present invention may be urea, melamine, cyanamide, guanidine hydrochloride, dicyandiamide, thiourea, etc., and preferably may be urea, but is not limited thereto as long as it corresponds to a nitrogen-rich organic compound capable of synthesizing a C3N5 compound.

[0030] The 'hydrazine' of the present invention is a liquid chemical used as rocket fuel, with the chemical formula N2H4. It has an odor similar to ammonia, a density similar to water, and exists in a liquid state within a temperature range similar to that of water.

[0031] In the present invention, the above '(a) step' may be a mixture of precursor compound : hydrazine : distilled water in a ratio of 5.0 g to 15.0 g : 0.5 g to 1.5 g : 1.0 g to 3.0 g, and specifically, the mixture of precursor compound : hydrazine : distilled water in a ratio of 10.0 g : 1.0 g : 2.0 g, but is not limited thereto. Additionally, the mixing of the above step (a) may be performed with external air blocked to produce C3N5.

[0032] In the present invention, the heating of the above '(b) step' is performed at 500°C to 600°C for 1 hour to 4 hours, specifically, it may be performed at 550°C for 2 hours, and the temperature may be increased by 1°C to 10°C per minute to reach 550°C, preferably by increasing the temperature by 4°C per minute to reach 550°C, and the heating may be performed for 2 hours after reaching the temperature to 550°C.

[0033] In the present invention, the above '(c)' may include a step of washing with distilled water and then freeze-drying to separate impurities, and the 'impurities' include urea and ammonia, etc., which may remain after the reaction.

[0034] In the present invention, in step (d), the ‘metal’ may be one or more selected from magnesium (Mg), manganese (Mn), and cobalt (Co), preferably magnesium, but not limited thereto. The ‘metal’ may be in powder form, and the ‘C3N5’ and the ‘metal’ may be mixed in a weight ratio of 1:1, but the weight ratio may be changed depending on the specific surface area of ​​the metal used.

[0035] Step (d) above may be performed by heating in a nitrogen atmosphere, and the heating in Step (d) may be performed at 650°C to 950°C for 1 hour to 3 hours, specifically, at 750°C for 2 hours. More specifically, for the heating, the temperature may be increased by 1°C to 10°C per minute to reach 750°C, preferably by increasing the temperature by 5°C per minute to reach 750°C, and after reaching the temperature to 750°C, heating may be performed for 2 hours.

[0036] In the present invention, the step of removing the metal in '(e)' may be performed using a hydrochloric acid solution, and the step of obtaining crystalline carbon may include a step of washing with distilled water and ethanol followed by freeze-drying.

[0037] As one embodiment for achieving the above objective, the present invention provides a crystalline carbon structure produced by the above manufacturing method.

[0038] In the present invention, the 'crystalline carbon structure' may have pores, and the size of the pores may be 19 nm to 31 nm, but is not limited thereto.

[0039] In the present invention, the 'crystalline carbon structure' may have an increased specific surface area compared to C3N5. Specifically, in the present invention, the 'crystalline carbon structure' has a specific surface area of ​​45 m² 2 g -1 to 500m 2 g -1 It may be, but is not limited to.

[0040] As one embodiment for achieving the above objective, the present invention provides an electrode catalyst comprising a crystalline carbon structure produced by the above manufacturing method.

[0041] The above electrode catalyst may be a mixture of carbon structures and platinum nanoparticles, and the mixing ratio of crystalline carbon and platinum nanoparticles may be a weight ratio of 95:5. Effects of the invention

[0043] The method for manufacturing a highly crystalline carbon structure according to the present invention can produce a crystalline carbon structure that has excellent oxidation resistance, is rich in azo dye, and has a high specific surface area due to the addition of hydrogen and metal powder, and also has the effect of producing the carbon structure in the shortest possible time because the manufacturing is carried out at a low temperature. Therefore, the carbon structure produced by this method for manufacturing a highly crystalline carbon structure can be usefully used as an energy-related support or individual carbon material, such as for secondary batteries, fuel cells, and water electrolysis. Brief explanation of the drawing

[0045] Figure 1 is a schematic diagram showing a method for manufacturing a crystalline carbon structural agent. Figure 2 shows the structure of the synthesized C3N5 as SEM images, TEM images, HAADF, and STEM mapping images. Figure 3 shows the results of the thermogravimetric analysis of the crystalline carbon structure. Figure 4 shows the structure of a crystalline carbon structure prepared using magnesium metal, as SEM and TEM images. Figure 5 shows the structure of a crystalline carbon structure prepared using magnesium metal as HAADF and STEM mapping images. Figure 6 shows the structure of a crystalline carbon structure prepared using cobalt metal as an SEM image, TEM image, HAADF, and STEM mapping image. Figure 7 shows the results of Raman analysis performed on crystalline carbon structures obtained using various metals. Figure 8 shows the results of XRD analysis performed on crystalline carbon structures obtained using various metals. Figure 9 shows the results of XPS analysis performed on crystalline carbon structures obtained using various metals. Figure 10 shows the ratio of nitrogen functional groups calculated through XPS analysis results for crystalline carbon structures obtained using various metals. Figure 11 shows the stability evaluation of an electrode catalyst using a crystalline carbon structure obtained using various metals. Figure 12 shows the results of measuring overpotentials at half-wave potential (E1 / 2) from an experiment on the oxygen reduction reaction (ORR) of a fuel cell cathode. Figure 13 shows the specific surface area of ​​a crystalline carbon structure and experimental results for an electric double layer capacitor. Specific details for implementing the invention

[0046] The present invention will be explained in more detail below through the following examples. However, these examples are intended to illustrate the invention and the scope of the invention is not limited to these examples.

[0048] Example 1. Preparation of a crystalline carbon structure

[0049] 1.1. Preparation of Supersaturated Solution

[0050] The manufacturing process of the overall crystalline carbon structure is shown in Fig. 1. First, a supersaturated urea solution was prepared by mixing urea, a C3N5 precursor compound, hydrazine, and distilled water (H2O) in a crucible. Since carbon nitride is not formed if the lid of the crucible is left open during the mixing process, the process was carried out with the lid closed. In preparing the supersaturated solution, the ratio of the components mixed was set so that the ratio of urea : hydrazine : distilled water was 10.0 g : 1.0 g : 2.0 g.

[0052] 1.2. Synthesis of Carbon Nitride

[0053] The supersaturated solution prepared in Example 1.1 was placed in a muffle furnace, and the temperature was increased by 4°C per minute to reach 550°C and maintained for 2 hours to synthesize C3N5. Since ammonia gas is generated during the heating process, thorough ventilation was performed.

[0054] Subsequently, to separate impurities from the synthesized C3N5, it was washed several times (at least 3 times) with distilled water, centrifuged at 4000 rpm for at least 5 minutes, and then freeze-dried. The impurities included urea and ammonia, which may remain after the reaction.

[0055] SEM, TEM, HAADF, and STEM mapping images of the synthesized C3N5 are shown in Fig. 2. Fig. 2(a) shows the SEM image, (b) shows the low-magnification TEM image, (c) shows the high-magnification TEM image, and (d) to (g) show the HAADF mapping image and STEM mapping image. From the TEM image, it was confirmed that the structure was in the form of a nanosheet, and considering the STEM mapping image, it was found that the ratio of carbon to nitrogen in C3N5 was similarly distributed. In addition, it was confirmed that no oxide layer was formed.

[0057] 1.3. Reaction between Carbon Nitride and Metal Catalysts

[0058] Various metal powders (Mg, Mn, Co, etc.) were mixed with the synthesized C3N5 and reacted. The metal powders and C3N5 were uniformly mixed using a mortar and pestle or a ball mill. Subsequently, the sample was introduced into a tube furnace under a nitrogen atmosphere, and the temperature was increased by 5°C per minute to reach 750°C, followed by heating for 2 hours. As a result, crystalline carbon was formed around the metal surface.

[0060] 1.4. Obtaining Crystalline Carbon

[0061] Since residual metals are present in the synthesized crystalline carbon, the metal residues were removed using a high-concentration hydrochloric acid solution. Safety precautions are necessary as the reaction between hydrochloric acid and metals generates hydrogen gas and heat, potentially causing sparks. Furthermore, since metals react with hydrochloric acid and ionize in the order of Mg > Mn > Co, Mg is the most effective for metal removal during the cleaning process.

[0062] After removing the residue, crystalline carbon was obtained by washing with distilled water and ethanol and then freeze-drying.

[0064] Example 2. Characterization of the prepared crystalline carbon

[0065] 2.1. Measurement of Gravity of Crystalline Carbon

[0066] The thermal properties and presence of crystalline carbon were confirmed by measuring weight changes with temperature using thermogravimetric analysis (TGA). It was confirmed that when only C3N5 was present, mass loss occurred after 500°C, and most of the mass was lost after 700°C. On the other hand, when C3N5 and metal powder were mixed in a 1:1 weight ratio and heated, mass loss occurred after 500°C, but it was confirmed that the mass loss decreased significantly after 600°C (Fig. 3). This is because crystalline carbon is formed on the metal surface, and this carbon is difficult to decompose at high temperatures.

[0068] 2.2. Structural Analysis of Crystalline Carbon Prepared Using Magnesium Metal

[0069] The structure of the crystalline carbon structure prepared using magnesium metal in the manufacturing process of Example 1 (Example 1.3) was analyzed. The results of the analysis are shown in Figures 4 and 5. Figure 4 (a) is a low-magnification SEM image, (b) is a high-magnification SEM image, (c) and (d) are low-magnification TEM images, and (e) is a high-magnification TEM image. Figures 5 (d) to (h) show HAADF mapping images and STEM mapping images.

[0070] Overlapping carbon layers were observed in SEM images of crystalline carbon produced by heat treatment with magnesium powder, and multiple carbon layers and internal hollow spaces were identified in TEM images magnified more than 1,000 times. These are pores formed after the removal of magnesium metal through acid treatment and serve as the source of the large surface area of ​​the carbon structure. Through HAADF and STEM mapping, nitrogen and carbon atoms were uniformly detected in the crystalline carbon structure, and the presence of some nitrogen and magnesium was confirmed. However, compared to C3N5, the nitrogen content was significantly reduced, and trace amounts of magnesium were confirmed to remain even after the washing process. Nevertheless, the impact of residual magnesium in actual catalytic activity experiments was negligible.

[0072] 2.3. Structural Analysis of Crystalline Carbon Prepared Using Cobalt Metal

[0073] The structure of the crystalline carbon structure prepared using cobalt metal in the manufacturing process of Example 1 (Example 1.3) was analyzed. The results of the analysis are shown in Fig. 6. Fig. 6 (a) and (b) are high-magnification SEM images, (c) and (d) are high-magnification TEM images, and (e) is an HAADF and STEM mapping image.

[0074] In the crystalline carbon produced by heat treatment with cobalt powder, pores formed by the removal of metal could be observed in the SEM images. Additionally, multiple layers of carbon covering the surface could be observed in the TEM images, and the hollow structure of the carbon interior was confirmed in both TEM and STEM mapping images. Therefore, it can be seen that a carbon structure with a large surface area was formed. Compared to crystalline carbon synthesized using magnesium powder, although the morphological characteristics differ, it was identified as a nitrogen-doped structure, and residual Co was confirmed to be present even after the washing process. However, in the actual catalytic activity experiments, the influence of the residual cobalt was negligible.

[0076] 2.4 Raman Analysis

[0077] The results of Raman analysis performed on crystalline carbon structures obtained using various metals are shown in Figure 7. Generally, carbon exhibits high stability against electrochemical oxidation-reduction reactions when arranged in a hexagonal crystal structure, such as in graphene and graphite. Graphene structures are mainly 1350 cm⁻¹ -1 D peak at 1580 cm -1 The G peak is observed at [location]. The D peak is identified as a defect, and it exhibits the characteristic of showing a higher peak as the degree of defects or substitutions in the hexagonal structure increases. The G peak is a peak commonly observed in graphite-related materials and is represented by the abbreviation for graphite. Consequently, the better the hexagonal structure of the carbon structure, the lower the D peak appears compared to the G peak, resulting in I (intensity) I D / I G The lower the ratio, the more it is considered a carbon structure with superior crystallinity. Based on this, Raman analysis was performed, and the results showed that when metal powder was used, I D / IG The ratios were found to be 0.27 for Mg, 0.82 for Mn, and 0.60 for Co, confirming that they exhibit superior crystallinity in the order of Mg > Co > Mn.

[0079] 2.5 X-ray Diffraction (XRD) Analysis

[0080] In XRD analysis, a wider and more biased (002) peak indicates lower graphite crystallinity in the carbon structure. To further analyze the crystallinity of carbon using XRD, the (002) peak was analyzed, and the results are shown in Fig. 8. The (002) peak of carbon nitride (C3N5), a crystalline carbon precursor, is 2θ=27.7 o It was observed in, and the (002) peak of crystalline carbon generated during the pyrolysis process is shifted to the left, known as the peak range of carbon nanosheets 26 o It was observed in the surroundings and was found to have formed a crystalline structure.

[0082] 2.6 X-ray Photoelectron Spectroscopy (XPS) Analysis Results

[0083] XPS analysis was performed to confirm the surface structure and oxidation state of the synthesized crystalline carbon.

[0084] In the case of C3N5, the C 1s peak exhibits CC and N=CN structures, which are common to carbon nitride. On the other hand, crystalline carbon commonly forms sp² structures that resemble hexagonal graphene. 2 A very high peak is observed (left diagram of Fig. 9).

[0085] In the case of C3N5, the N 1s peak shows the C=NC peak, which is common to carbon nitride, at 397.9 eV, and the CN=NC peak, which is characteristic of C3N5, can be observed at 399.6 eV. On the other hand, in crystalline carbon, the peaks of the four representative types of N-doped carbon (pyridinic N, pyrolic N, graphitic N, oxidized N) are clearly observed (right diagram of Fig. 9).

[0086] As shown in Table 1, the XPS analysis results of crystalline carbon structures prepared using various metal powders show that the ratio of nitrogen to carbon is lowest in the case of crystalline carbon prepared using magnesium powder compared to other metals.

[0087]

[0088] Figure 10 shows the results of calculating the nitrogen functional group ratio based on XPS analysis. Crystalline carbon prepared using magnesium powder, which exhibits the lowest nitrogen-to-carbon ratio, demonstrates the best ability to remove nitrogen from carbon nitride. Furthermore, due to the low number of doping / defect sites, excellent results were obtained in terms of crystallinity (ID / IG values ​​in Raman), specific surface area, and conductivity.

[0089] On the other hand, crystalline carbon prepared using cobalt powder was found to have excellent electrode activity for oxygen reduction reactions due to the high ratio of pyridinic N to graphitic N.

[0091] 2.7. Electrochemical Stability Experiment

[0092] A crystalline carbon structure synthesized from metal powders of magnesium, manganese, and cobalt was used as a support and mixed with platinum nanoparticles (crystalline carbon : platinum nanoparticles = 95 : 5 wt.%) to evaluate the activity of the fuel cell cathode electrode catalyst. The experiment was conducted using a rotating disc electrode, and the results are shown in the voltammogram in Fig. 11. The solid line in Fig. 11 represents the results measured before the stability evaluation, and the dotted line represents the results measured after 5,000 cycles of rapidly cycling through the potential region of 1.0–1.5 V, where oxidation of the support carbon occurs rapidly in an alkaline solution.

[0093] Meanwhile, g-C3N4 and C3N5 are obtained depending on the presence or absence of hydrazine, so the distinction is indicated in red or blue. Figures 11 (a) to (c) show crystalline carbon supports obtained from metal powders of magnesium, manganese, and cobalt, respectively. In the synthesis of crystalline carbon using cobalt, the change before and after the stability experiment was evaluated to be the lowest, so the stability of the crystalline carbon is evaluated to be the best.

[0094] Meanwhile, Table 2 and Figure 12 show the overpotentials measured at the half-wave potential (E1 / 2) from experiments on the oxygen reduction reaction (ORR) of the fuel cell cathode.

[0095] Precursor Mg, E 1 / 2 Mn, E 1 / 2 Co, E 1 / 2 before after △E before after △E before after △E gC 3 N 4 447 mV 455 mV 8 425 mV 443 mV 18 429 mV 445 mV 16 C 3 N 5 443 mV 448 mV 5 438 mV 467 mV 29 384 mV 390 mV 6

[0096] Regarding stability changes, the potential change was lowest in metal powders using magnesium and cobalt with C3N5 precursors, and the best stability results were observed particularly in Co powder. Considering the onset potential and half-wave potential, which are evaluation factors for fuel cell ORR catalytic activity, the best catalytic activity was exhibited under conditions using C3N5 precursors and cobalt powder. It was also confirmed that the change in current density was smallest when using cobalt powder.

[0098] 2.8. Measurement of Specific Surface Area of ​​Crystalline Carbon

[0099] Figure 13 and Table 3 show the specific surface area of ​​the crystalline carbon structure and the experimental results for the electric double layer capacitor. As shown in Table 3 below, it was confirmed that pores ranging in size from 19 to 31 nm were formed in all the manufactured crystalline carbons. It was confirmed that the specific surface area of ​​all crystalline carbons obtained from metal powder increased compared to the precursor C3N5 (Figure 13(a)). In addition, it was confirmed that the electric double layer gradient area of ​​all crystalline carbons obtained from metal powder increased compared to the precursor C3N5 (Figure 13(b)). In particular, it was confirmed that the specific surface area and electric double layer gradient area were widest for the crystalline carbon using Mg powder, which showed the best removal of metal and nitrogen.

[0100]

[0101] From the foregoing description, those skilled in the art to which the present invention pertains will understand that the present invention may be implemented in other specific forms without altering its technical concept or essential features. In this regard, the embodiments described above should be understood as illustrative in all respects and not restrictive. The scope of the present invention should be interpreted as including all modifications or variations derived from the meaning and scope of the claims set forth below and their equivalents, rather than from the detailed description above.

Claims

Claim 1 A method for manufacturing a carbon structure comprising the following steps: (a) preparing a supersaturated solution by mixing a C3N5 precursor compound, distilled water, and hydrazine; (b) synthesizing C3N5 by heating the supersaturated solution; (c) removing impurities from the synthesized C3N5; (d) mixing the C3N5 from which impurities have been removed with a metal and heating it; and (e) removing the metal to obtain crystalline carbon, wherein the metal in step (d) is one or more selected from magnesium (Mg), manganese (Mn), and cobalt (Co). Claim 2 A method for manufacturing a carbon structure according to claim 1, wherein the C3N5 precursor compound in step (a) is urea. Claim 3 A method for manufacturing a carbon structure according to claim 1, wherein step (a) involves mixing a precursor compound : hydrazine : distilled water in a ratio of 5.0 g to 15.0 g : 0.5 g to 1.5 g : 1.0 g to 3.0 g. Claim 4 A method for manufacturing a carbon structure according to claim 1, wherein the mixing in step (a) is performed while blocking external air. Claim 5 A method for manufacturing a carbon structure according to claim 1, wherein the heating in step (b) is performed at 500°C to 600°C. Claim 6 A method for manufacturing a carbon structure according to claim 5, wherein the heating in step (b) is performed at 500°C to 600°C for 1 hour to 4 hours. Claim 7 A method for manufacturing a carbon structure according to claim 1, wherein step (c) includes the step of washing with distilled water and then freeze-drying. Claim 8 delete Claim 9 A method for manufacturing a carbon structure according to claim 1, wherein the metal in step (d) is in powder form. Claim 10 A method for manufacturing a carbon structure according to claim 1, wherein the heating in step (d) is performed in a nitrogen atmosphere. Claim 11 A method for manufacturing a carbon structure according to claim 1, wherein the heating in step (d) is performed at 650°C to 950°C. Claim 12 A method for manufacturing a carbon structure according to claim 11, wherein the heating in step (d) is performed at 650°C to 950°C for 1 hour to 3 hours. Claim 13 A method for manufacturing a carbon structure according to claim 1, wherein in step (d), C3N5 and the metal are mixed in a weight ratio of 1:

1. Claim 14 A method for manufacturing a carbon structure according to claim 1, wherein the step of removing the metal in step (e) is performed using a hydrochloric acid solution. Claim 15 A method for manufacturing a carbon structure according to claim 1, wherein the step of obtaining crystalline carbon in step (e) comprises the step of washing with distilled water and ethanol and then freeze-drying. Claim 16 A crystalline carbon structure manufactured by any one of the manufacturing methods of paragraphs 1 through 7 and paragraphs 9 through 15. Claim 17 In paragraph 16, the crystalline carbon structure is a crystalline carbon structure having pores. Claim 18 A crystalline carbon structure according to claim 17, wherein the pore size is 19 nm to 31 nm. Claim 19 In paragraph 16, the crystalline carbon structure has a specific surface area of ​​45 m² 2 g -1 to 500m 2 g -1 A crystalline carbon structure that is. Claim 20 An electrode catalyst comprising a crystalline carbon structure manufactured by any one of the manufacturing methods of claims 1 to 7 and claims 9 to 15. Claim 21 In paragraph 20, the electrode catalyst is an electrode catalyst in which a carbon structure and platinum nanoparticles are mixed.

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