KR102465836B1 - A transition metal nitride-carbon catalyst composite, a method for manufacturing the same, a electrode catalyst for fuel cell comprising the transition metal nitride-carbon catalyst composite, a fuel cell comprising the electrode catalyst - Google Patents

Abstract

The present invention relates to a transition metal nitride-carbon catalyst composite, a method for preparing the same, an electrode catalyst for a fuel cell including the transition metal nitride-carbon catalyst composite, and a fuel cell including the electrode catalyst. The transition metal nitride-carbon catalyst composite can reduce manufacturing costs by adsorbing a non-noble metal-based transition metal-macrocycle structure instead of an expensive precious metal on a carbon support, and the active points are dispersed at the atomic level, so when applied to the electrode catalyst, the oxygen reduction reaction Activity and structural stability can be significantly improved. In addition, by optimizing the type and heat treatment conditions of the carbon support and precursor, the manufacturing process is simple, the aggregation of active points is prevented, and the degree of dispersion and durability of catalytic active points can be improved.

Description

A transition metal nitride-carbon catalyst composite, a method for manufacturing the same, an electrode catalyst for a fuel cell including the transition metal nitride-carbon catalyst composite, and a fuel cell including the electrode catalyst the same, a electrode catalyst for fuel cell comprising the transition metal nitride-carbon catalyst composite, a fuel cell comprising the electrode catalyst}

The present invention relates to a transition metal nitride-carbon catalyst composite, a method for preparing the same, an electrode catalyst for a fuel cell including the transition metal nitride-carbon catalyst composite, and a fuel cell including the electrode catalyst.

A fuel cell is an electrochemical energy conversion device in which hydrogen and oxygen meet to generate water and electricity. Among fuel cells, alkaline fuel cells that use alkaline solutions such as KOH and NaOH as electrolytes can alleviate corrosion problems of electrodes and stacks compared to fuel cells in acidic conditions, but have relatively low performance. commercialization is delayed. Since the relatively high level of performance reported so far uses a platinum catalyst and the system price is relatively high, research on the development of a non-noble metal-based catalyst to replace expensive noble metal catalysts is essential to increase the economics of the system.

Research on non-noble metal-based catalysts has proposed non-noble metal carbides, non-noble metal oxides and non-noble metal nitride-carbon composites, and carbon-based materials doped with non-metal-containing hetero-elements. Among them, the M-N-C (M = Fe, Co, Cu, Mn, etc.) catalyst, which is a non-noble metal nitride-carbon complex structure, is easy to synthesize and has excellent performance, and is reported as the most promising catalyst to replace platinum.

Such an M-N-C catalyst is synthesized through heat treatment after supporting a metal precursor including nitrogen species on a carbon carrier, or through ammonia heat treatment to adsorb a metal on a carbon carrier and support nitrogen species. However, it is important to increase the dispersion of the active point because the active point of the catalyst is greatly reduced when the active metal is agglomerated during the high-temperature heat treatment process, which is an essential process for the activity and stability of the catalyst.

Recently, research results have been reported that show high oxygen reduction activity when active sites are dispersed at the atomic level. A highly dispersed catalyst at the atomic level can be manufactured in two ways. First, a method of forming an active site by preventing the active metal from aggregating as the sacrificial metal sublimes during heat treatment, such as ZIF (Zeolitic Imidazolate Frameworks), and There is a method of melting the agglomerated metal after heat treatment through acid treatment.

However, these methods have disadvantages in that the manufacturing process is complex as well as in terms of cost. Therefore, there is a need for a process capable of producing an electrocatalyst having a highly dispersed M-N-C structure in which the active metal is not agglomerated and the active metal is not agglomerated without a post-treatment process.

Korean Patent Publication No. 2010-0119833

In order to solve the above problems, an object of the present invention is to provide a transition metal nitride-carbon catalyst composite in which non-noble metal-based transition metal-macrocycle structures are dispersed at the atomic level.

Another object of the present invention is to provide an electrode catalyst for a fuel cell with significantly improved oxygen reduction activity and structural stability, including the transition metal nitride-carbon catalyst composite.

Another object of the present invention is to provide a fuel cell including the electrode catalyst.

Another object of the present invention is to provide a device including a fuel cell.

Another object of the present invention is to provide a method for preparing a transition metal nitride-carbon catalyst composite with a simple manufacturing process because no post-treatment is required.

The present invention is a carbon support; and a non-noble metal-based transition metal-macrocycle structure adsorbed on the carbon support, wherein the transition metal nitride-carbon catalyst complex is formed on the carbon support. A transition metal nitride-carbon catalyst complex in which macrocycle structures are dispersed at the atomic level through self-alignment by pi-pi (π-π) bonds is provided.

In addition, the present invention provides an electrode catalyst for a fuel cell comprising the transition metal nitride-carbon catalyst composite.

In addition, the present invention provides a fuel cell including the electrode catalyst.

In addition, the present invention provides a device including the fuel cell, wherein the device is a transportation device or an energy storage device.

In addition, the present invention comprises the steps of preparing a mixture by mixing a carbon support and a non-noble metal-based transition metal-macrocycle precursor in an organic solvent; and preparing a transition metal nitride-carbon catalyst composite by heat-treating the mixture under an injection gas, wherein the transition metal nitride-carbon catalyst composite has a non-noble metal-based transition metal-macrocycle structure on the carbon support. -Provides a method for producing a transition metal nitride-carbon catalyst composite adsorbed in a structure dispersed at the atomic level through self-alignment by pi (π-π) bonds.

The transition metal nitride-carbon catalyst composite of the present invention can reduce manufacturing costs by adsorbing a non-noble metal-based transition metal-macrocycle structure instead of an expensive precious metal to a carbon support, and active points are dispersed at the atomic level when applied to an electrode catalyst. The oxygen reduction reaction activity and structural stability can be remarkably improved.

In addition, the transition metal nitride-carbon catalyst composite of the present invention optimizes the type of carbon support and precursor and heat treatment conditions, thereby increasing the number of active points. It prevents aggregation, can improve the dispersion of catalytic active points and durability, and has the advantage of a simple manufacturing process because there is no need for a post-treatment process in which the agglomerated metal is dissolved by acid treatment.

The effects of the present invention are not limited to the effects mentioned above. It should be understood that the effects of the present invention include all effects that can be inferred from the following description.

1 is a graph showing X-ray diffraction pattern results for FePC/TEGO prepared in Example 1 and Comparative Examples 1 to 3.
2 is a transmission electron microscope image of FePC/TEGO prepared in Example 1 and Comparative Examples 1 to 3.
Figure 3 shows the measurement results using the linear scanning potential method (LSV) for the electrode catalyst using the composites prepared in Example 1 and Comparative Examples 1 to 4.
4 shows measurement results using cyclic voltammetry (CV) for a commercially available platinum catalyst.
5 shows measurement results using cyclic voltammetry (CV) for the electrode catalyst using the iron nitride-carbon catalyst composite prepared in Example 1.

Hereinafter, the present invention will be described in more detail as an embodiment.

The present invention relates to a transition metal nitride-carbon catalyst composite, a method for preparing the same, an electrode catalyst for a fuel cell including the transition metal nitride-carbon catalyst composite, and a fuel cell including the electrode catalyst.

In the past, catalysts with a structure in which only metal precursors are adsorbed on a carbon support have been mainly used, but these catalysts have poor durability due to low structural stability, and have problems in that catalyst particles aggregate together and consequently reduce the catalytic activity of the oxygen reduction reaction. there was.

Accordingly, in the present invention, the manufacturing cost can be reduced by adsorbing a non-noble metal-based transition metal-macrocycle structure on a carbon support instead of an expensive precious metal to prepare a transition metal nitride-carbon catalyst composite, and active points are dispersed at the atomic level to form an electrocatalyst. When applied to the oxygen reduction reaction activity can be significantly improved. In addition, the transition metal nitride-carbon catalyst composite can prevent aggregation of active sites (or metals) and improve dispersion and durability of active sites by optimizing the types of carbon supports and precursors and heat treatment conditions. It has the advantage of a simple manufacturing process because it does not require a post-treatment process that dissolves it by acid treatment.

Specifically, the present invention is a carbon support; and a non-noble metal-based transition metal-macrocycle structure adsorbed on the carbon support, wherein the transition metal nitride-carbon catalyst complex is formed on the carbon support. A transition metal nitride-carbon catalyst complex in which macrocycle structures are dispersed at the atomic level through self-alignment by pi-pi (π-π) bonds is provided.

In the present specification, "adsorption" means a state in which the carbon support and the non-noble metal-based transition metal-macrocycle structure are physically or chemically bonded.

The carbon support is graphene oxide, thermal exfoliation of graphene oxide, graphene, carbon black, Ketjen black, carbon nanotubes ( Carbon Nano Tube), carbon nano fiber (Carbon Nano Fiber), and may be at least one selected from the group consisting of graphite carbon.

Preferably, the carbon support may be graphene oxide, thermally exfoliated graphene oxide, or a mixture thereof, and most preferably, thermally exfoliated graphene oxide. In particular, the thermally exfoliated graphene oxide has higher electrical conductivity than other carbon supports and has a large specific surface area, so that the effect of improving the active area of the catalyst is very good.

The non-noble metal-based transition metal-macrocycle structure is a non-noble metal in at least one macrocycle compound selected from the group consisting of porphyrin, tetraphenylporphyrin, tetramethoxyphenylporphyrin and phthalocyanine. It may be made of a structure in which a system transition metal is coordinated. The non-noble transition metal may be at least one selected from the group consisting of Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ru, Rh, Pd, Sn, W, and Os. . Preferably, the non-noble metal-based transition metal may be at least one selected from the group consisting of Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Sn, and W, and more preferably It may be Fe, Co or mixtures thereof, and most preferably Fe.

Preferably, the non-noble metal transition metal-macrocycle structure is iron-phthalocyanine (Fe-PC), cobalt-phthalocyanine (Co-PC), iron/cobalt-phthalocyanine (Fe/Co- phthalocyanine (Fe/Co-PC), Iron(III)-tetramethoxyphenylporphyrin (Fe-TMPP), Cobalt(II)-tetramethoxyphenylporphyrin (Co-TMPP) and iron / Cobalt-tetramethoxyphenylporphyrin (Iron (III) / Cobalt (II) - tetramethoxyphenylporphyrin, Fe / Co-TMPP) may be at least one selected from the group consisting of.

More preferably, the non-noble metal-based transition metal-macrocycle structure may be iron-phthalocyanine, cobalt-phthalocyanine, or iron/cobalt-phthalocyanine, and most preferably iron-phthalocyanine. In particular, the iron-phthalocyanine has excellent electronic conductivity and oxygen reduction activity compared to other non-noble metal-based transition metal-macrocycle structures.

The non-noble metal-based transition metal-macrocycle structure has the best oxygen reduction activity when metal particles, which are active sites, are dispersed at the atomic level. As in the case of conventional catalysts, when metals aggregate with each other during high-temperature heat treatment, the concentration of catalytic active sites decreases, and thus the oxygen reduction reaction activity may decrease. Accordingly, the transition metal nitride-carbon catalyst composite can prevent aggregation of active sites (metal particles) during heat treatment by adjusting the time of exposure to high temperature, thereby improving the activity of the catalyst by highly dispersing the active sites at the atomic level.

The transition metal nitride-carbon catalyst composite is contained in an amount of 10 to 80 parts by weight, preferably 20 to 50 parts by weight, more preferably 25 to 35 parts by weight, based on 100 parts by weight of the carbon support. , most preferably 30 parts by weight. At this time, if the content of the non-noble metal-based transition metal-macrocycle structure is less than 10 parts by weight, the oxygen reduction reaction activity may not be sufficiently exhibited. Reduction reaction activity may be significantly lowered.

As a result of XRD analysis, the transition metal nitride-carbon catalyst composite may show an effective peak only in the range of 2θ of 24° to 26°. The effective peak may be a carbon peak.

In the present invention, a 'significant or effective' peak means a peak that is repeatedly detected in a pattern that can be seen in the art as substantially the same in analysis data such as Raman or XRD without being significantly affected by analysis conditions or analysis performers, It is clear that a person skilled in the art can easily determine whether a corresponding peak is an effective peak.

In the case of having the above crystal structure of XRD characteristics, although not explicitly described in the following examples or comparative examples, the obtained transition metal nitride-carbon catalyst composite has a non-noble metal-based transition metal-macrocycle structure on the carbon support. It was confirmed that the structural stability of the catalyst was significantly improved due to the stronger pi-pi (π-π) bond structure, excellent durability and thermal stability, and uniform self-alignment of catalytic active points.

Meanwhile, the present invention provides an electrode catalyst for a fuel cell including the transition metal nitride-carbon catalyst composite.

In addition, the present invention provides a fuel cell including the electrode catalyst.

In addition, the present invention is a device including the fuel cell, and the device may be a transportation device or an energy storage device.

In addition, the present invention comprises the steps of preparing a mixture by mixing a carbon support and a non-noble metal-based transition metal-macrocycle precursor in an organic solvent; and preparing a transition metal nitride-carbon catalyst composite by heat-treating the mixture under an injection gas, wherein the transition metal nitride-carbon catalyst composite has a non-noble metal-based transition metal-macrocycle structure on the carbon support. -Provides a method for producing a transition metal nitride-carbon catalyst composite adsorbed in a structure dispersed at the atomic level through self-alignment by pi (π-π) bonds.

The method for preparing the transition metal nitride-carbon catalyst composite is a simple bottom-up process of directly adsorbing a non-noble metal-based transition metal-macrocycle precursor on the carbon support and controlling the time the precursor is exposed to a high temperature. Thus, the transition metal nitride-carbon catalyst composite can be prepared. This manufacturing process is efficient and simple compared to conventional top-down processes that use sacrificial metals to prevent catalytic active site aggregation or require post-processing to remove agglomerated metal species. Catalyst complexes can be prepared.

In order to apply the transition metal nitride-carbon catalyst composite as an electrode catalyst, it is important to increase the catalytic active point. Accordingly, in the present invention, during the preparation of the transition metal nitride-carbon catalyst composite, the non-noble metal-based transition metal-macrocycle structure is formed on the carbon support by controlling the types of the carbon support and the precursor, and the heat treatment conditions. It was confirmed that a highly dispersed catalyst can be prepared by forming a highly dispersed transition metal nitride-carbon catalyst composite structure at the atomic level through self-alignment by pi (π-π) bonds.

Specifically, in the step of preparing the mixture, 10 to 80 parts by weight, preferably 20 to 50 parts by weight, more preferably 25 to 50 parts by weight of a non-noble metal-based transition metal-macrocycle structure is added to an organic solvent based on 100 parts by weight of the carbon support. 35 parts by weight, most preferably 30 parts by weight can be mixed.

The organic solvent is ethanol, acetone, dimethylformamide, acetonitrile, anisole, benzene, chlorobenzen, chloroform, dimethyl It may be at least one selected from the group consisting of acetamide, methanol, N-methyl-2-pyrrolidone, tetrahydrofuran, and dimethyl sulfoxide. . Preferably, the organic solvent may be at least one selected from the group consisting of dimethylformamide, dimethylacetamide and acetonitrile, and most preferably dimethylformamide.

In the step of preparing the transition metal nitride-carbon catalyst complex, the injection gas may be at least one selected from the group consisting of hydrogen, ammonia, argon, and nitrogen, preferably ammonia, nitrogen, or a mixture thereof, and most preferably It may be ammonia.

In the step of preparing the transition metal nitride-carbon catalyst composite, heat treatment may be performed at 400 to 1200 °C for 0.1 to 4 minutes. During the heat treatment, the temperature of the sintering furnace is raised in advance to the process temperature, and then the mixture is exposed to a high temperature to prepare the transition metal nitride-carbon catalyst composite having an active point structure controlled according to the time of exposure to the process temperature.

When the non-noble metal-based transition metal-macrocycle precursor is physically adsorbed on the carbon support, durability may be deteriorated, and thus heat treatment at a high temperature is essential to improve structural stability. In addition, since the non-noble metal-based transition metal-macrocycle structure is prone to aggregation and has low electronic conductivity, the oxygen reduction reaction activity can be greatly reduced. That is, during heat treatment for structural stability, it is very important to optimize heat treatment conditions in order to form catalytic active sites in which the transition metal nitride-carbon catalyst complex is highly dispersed at the atomic level. Accordingly, the heat treatment is performed at 400 to 1200 ° C for 0.1 to 4 minutes, preferably at 600 to 1100 ° C for 1.5 to 3.5 minutes, more preferably at 900 to 1000 ° C for 2 to 3 minutes, most preferably at 950 ° C. It can be done in 2.5 minutes. At this time, if the heat treatment temperature is less than 400 ° C or the heat treatment time is less than 0.1 minute, the structural stability of the non-noble metal-based transition metal-macrocycle structure adsorbed on the carbon support is reduced, so that the durability of the oxygen reduction reaction may not meet expectations. have. Conversely, if the heat treatment temperature exceeds 1200 ° C or the heat treatment time exceeds 4 minutes, the non-noble metal-based transition metal-macrocycle structure adsorbed on the carbon support may be exposed to high temperatures for a long time, resulting in aggregation and collapse of active points. have.

Preparing a carbon support before preparing the mixture; may further include. In detail, the manufacturing of the carbon support may include ball milling graphite; supplying humidified air to the ball-milled graphite to remove amorphous carbon; preparing graphite oxide by oxidizing the graphite from which the amorphous carbon is removed; and preparing thermally exfoliated graphene oxide by thermally exfoliating the graphite oxide.

In the ball milling of the graphite, ball milling may be performed for 30 minutes to 5 hours using a high energy ball mill device.

In the step of removing the amorphous carbon, humidified air (Air) may be supplied at a rate of 10 to 200 ml/hr under conditions of a temperature of 100 to 600 °C.

In the step of preparing the thermally exfoliated graphene oxide, thermal exfoliation may be performed at a temperature of 300 to 1000 °C for 30 seconds to 1 hour.

In particular, although not explicitly described in the following Examples or Comparative Examples, in the method for preparing a transition metal nitride-carbon catalyst composite according to the present invention, the types of the carbon support and the non-noble metal-based transition metal-macrocycle precursor After applying the transition metal nitride-carbon catalyst composite prepared by varying the mixing ratio, organic solvent, type of gas injected during heat treatment, heat treatment temperature and time as an electrode catalyst to a fuel cell, a long-term stability test was conducted by a conventional method. did At this time, the voltage was 1.2V, and the power density after 100 hours of operation was evaluated.

As a result, unlike other conditions and other numerical ranges, when all of the following conditions were satisfied, the maximum power density of the battery showed high activity of 350 mW/cm ² , and the power density reduction rate after 100 hours of operation was about 10% or less. confirmed that Through this, it was found that the long-term stability and catalytic activity of the fuel cell were very excellent due to the strong bonding effect of the carbon support and the non-noble metal-based transition metal-macrocycle structure. ① the carbon support is thermal exfoliation of graphene oxide, ② the non-noble metal-based transition metal-macrocycle precursor is Fe-phthalocyanine (Fe-PC), and ③ the organic solvent is dimethylformamide, ④ the injection gas is ammonia, ⑤ heat treatment is performed at 900 to 1000 ° C. for 2 to 5 minutes in the step of preparing the transition metal nitride-carbon catalyst composite, and ⑥ the transition metal The nitride-carbon catalyst composite may include 25 to 35 parts by weight of a non-noble metal-based transition metal-macrocycle structure based on 100 parts by weight of the carbon support.

However, when any one of the above six conditions is not satisfied, the maximum power density of the battery is lowered to 200 mW/cm ² or less, and the power density decrease rate after 100 hours of operation is greatly increased to about 25% or more. It was found that the long-term stability was also rapidly deteriorated due to the low activity for the oxygen reduction reaction.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited by the following examples.

Example 1: FePC/TEGO Preparation

(1) Preparation of thermally exfoliated graphene oxide (TEGO)

Ball milling was performed for 1 hour using a ball mill (High energy ball mill emax) on graphite in powder form. Humidified air was supplied to the ball-milled graphite at a rate of 10 ml/hr to remove amorphous carbon at 300 °C. Then, wet air oxidation was performed on the graphite from which the amorphous carbon was removed to prepare graphite oxide. Thermal exfoliation was performed on the graphite oxide at a temperature of 600° C. for 1.5 minutes to prepare thermal exfoliated graphene oxide (TEGO).

(2) Manufacture of iron nitride-carbon catalyst composite

30 parts by weight of iron phthalocyanine, a non-precious transition metal-macrocycle precursor, was added to DMF (N, N-Dimethylformamide), an organic solvent, based on 100 parts by weight of TEGO, and stirred at room temperature for 12 hours to obtain the TEGO A mixture was prepared by adsorbing the iron phthalocyanine on the surface. Then, the mixture was put in a centrifuge, washed with acetone, and dried in an oven at 60° C. to obtain a powdery mixture. Then, after raising the temperature of the sintering furnace in advance to be close to the process temperature, the powdery mixture was heat-treated at a high temperature of 950 ° C. for 2.5 minutes in an ammonia atmosphere to obtain an iron nitride-carbon catalyst composite (FePC/TEGO, 950NH ₃ , 2.5 min) was synthesized. In Example 1, compared to Comparative Example 2, in order to minimize the exposure of the catalyst to a high temperature, the temperature of the firing furnace was raised to a preset temperature, and then the mixture was placed in the center of the firing furnace and heat treated to prepare a catalyst composite.

Comparative Example 1

In the same manner as in Example 1, 30 parts by weight of iron phthalocyanine, a non-precious transition metal-macrocycle precursor, was added to DMF (N, N-Dimethylformamide), an organic solvent, based on 100 parts by weight of TEGO, and room temperature by stirring for 12 hours to prepare an iron nitride-carbon catalyst composite (FePC/TEGO) in which the iron phthalocyanine is bonded to the surface of the TEGO. Heat treatment was not applied to the iron nitride-carbon catalyst composite.

Comparative Example 2

Iron nitride-carbon catalyst was carried out in the same manner as in Example 1, except that the heat treatment was performed at 950 ° C. for 2.5 minutes by placing the powder mixture in advance at the center of the furnace at room temperature and raising the temperature to a set temperature in an ammonia atmosphere during heat treatment. A composite (FePC/TEGO, 950NH ₃ HT (Heat Treatment) 2.5 min) was prepared.

Comparative Example 3

An iron nitride-carbon catalyst composite (FePC/TEGO, 950NH ₃ , 5 min) was prepared in the same manner as in Example 1, except that heat treatment was performed at 950° C. for 5 minutes.

Comparative Example 4

A Pt/C composite used as a commercial electrocatalyst was prepared.

Experimental Example 1: X-ray diffraction (XRD) and transmission electron microscope (TEM) analysis

X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyzes were performed to confirm the catalyst structure of FePC/TEGO prepared in Example 1 and Comparative Examples 1 to 3. The results are shown in Figure 1.

1 is a graph showing X-ray diffraction pattern results for FePC/TEGO prepared in Example 1 and Comparative Examples 1 to 3. Referring to FIG. 1, in Example 1 (FePC/TEGO, 2.5 min), only the carbon (C) peak was observed in the range of 2θ from 24° to 26°. On the other hand, in the case of Comparative Example 1 (FePC/TEGO) in which heat treatment was not performed, a carbon (C) peak was observed in the range of 2θ of 24 ° to 26 °, and an iron phthalocyanine precursor peak was observed in the range of 5 ° to 16 °. It became. In the case of Comparative Example 2 (FePC/TEGO, HT 2.5 min) and Comparative Example 3 (FePC/TEGO, 5 min), in addition to the carbon peak, 2θ ranged from 35° to 37°, from 40° to 42°, and from 44° to 46°. Iron oxide peaks of Fe ₂ O ₃ and Fe ₃ O ₄ were respectively observed in the ° range. Through this, in Example 1, the iron particles are atomically dispersed so that the crystallization peak of the iron oxide does not appear at all, whereas as in Comparative Examples 2 and 3, the iron oxide crystallizes due to the aggregation of the iron particles as the heat treatment time increases. It was found that peaks appeared.

2 is a transmission electron microscope image of FePC/TEGO prepared in Example 1 and Comparative Examples 1 to 3. Referring to FIG. 2, in the case of Comparative Example 1 (a), it can be confirmed that the iron phthalocyanine precursor is physically adsorbed on the plate-like carbon support, and Comparative Example 3 (c) and Comparative Example 2 (d) In the case of , it was confirmed that iron oxide particles agglomerated on the plate-like carbon support appeared. At this time, it was found that the iron oxide particles were agglomerated and aggregated into particles as the heat treatment time increased.

On the other hand, in the case of Example 1 (b), as the heat treatment was performed at a high temperature for a short time of 2.5 minutes, it was confirmed that iron was highly dispersed at the atomic level in the plate-like carbon support, and no catalyst particles were observed. It was confirmed through the X-ray diffraction analysis of FIG. 1 that the iron particles were iron oxides formed by aggregation as the heat treatment time increased. Through this, it was found that when the time exposed to a high temperature during the heat treatment was prolonged, the iron oxide was agglomerated.

Experimental Example 2: Linear Scanning Potential (LSV) Analysis

Using the composites prepared in Example 1 and Comparative Examples 1 to 4 as an electrode catalyst, the oxygen reduction reaction polarization curve of the catalyst was measured by Linear Sweep Voltammetry (LSV) using a potentioatat. . As the measurement conditions, a 0.1M KOH aqueous solution purged with oxygen for 1 hour was used as the electrolyte, and glassy carbon was coated with an electrocatalyst as a working electrode. The results are shown in Figure 3.

Figure 3 shows the measurement results using the linear scanning potential method (LSV) for the electrode catalyst using the composites prepared in Example 1 and Comparative Examples 1 to 4. Referring to FIG. 3, in particular, in the case of Example 1, it was confirmed that the activity of the oxygen reduction reaction was the most excellent compared to the electrode catalysts of Comparative Examples 1 to 3 and the commercially available platinum/carbon catalyst of Comparative Example 4. Through this, it was found that when the catalyst was exposed to high temperature for a short time, the active sites were highly dispersed at the atomic level on the carbon support, and the activity for the oxygen reduction reaction was increased due to these structural characteristics of the active sites of the catalyst. In the case of Comparative Examples 1 to 3, it was found that the oxygen reduction reaction performance was low as the time of exposure to high temperature during heat treatment increased, metal aggregation occurred, and the active point was relatively decreased.

Experimental Example 3: Cyclic Voltammetry (CV) Analysis

Using a commercial platinum catalyst and the iron nitride-carbon catalyst composite prepared in Example 1 as an electrode catalyst, cyclic voltammetry was performed to confirm the change in oxygen reduction reaction performance of the catalyst after durability evaluation conducted under half-cell conditions of the catalyst ( It was measured using Cyclic Voltammetry (CV). Cyclic Voltammetry (CV) measured the oxygen reduction reaction polarization curve after 10,000 cycles in the 0.65 to 1.05V section at a scan rate of 100 mV. The results are shown in Figures 4 and 5.

4 shows measurement results using cyclic voltammetry (CV) for a commercially available platinum catalyst. Referring to FIG. 4, in the case of a commercial platinum catalyst, it was confirmed that the oxygen reduction reaction performance was reduced to 42 mV compared to the initial half-wave potential.

5 shows measurement results using cyclic voltammetry (CV) for the electrode catalyst using the iron nitride-carbon catalyst composite prepared in Example 1. Referring to FIG. 5, in the case of Example 1, it was confirmed that the oxygen reduction reaction performance was reduced by about 6 mV compared to the initial half-wave potential. When these results were compared with the commercially available platinum catalyst of FIG. 4, it was found that the iron nitride-carbon catalyst composite electrode catalyst had much better durability than the commercially available platinum catalyst.

Claims (16)

delete delete delete delete delete delete delete delete delete delete preparing a mixture by mixing a carbon support and a non-noble metal-based transition metal-macrocycle precursor in an organic solvent; and
Heat-treating the mixture under an injection gas to prepare a transition metal nitride-carbon catalyst composite;
The transition metal nitride-carbon catalyst complex is adsorbed on the carbon support in a structure in which non-noble metal-based transition metal-macrocycle structures are dispersed at the atomic level through self-alignment by pi-pi (π-π) bonds,
The carbon support is thermal exfoliation of graphene oxide,
The non-noble metal-based transition metal-macrocycle precursor is iron-phthalocyanine (Fe-PC),
The organic solvent is dimethylformamide,
The injection gas is ammonia,
In the step of preparing the transition metal nitride-carbon catalyst composite, heat treatment is performed at 900 to 1000 ° C. for 2 to 3 minutes,
The transition metal nitride-carbon catalyst composite comprises 25 to 35 parts by weight of a non-noble metal-based transition metal-macrocycle structure based on 100 parts by weight of the carbon support. delete delete delete delete delete

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