KR20220058260A - Precious metal single atom-nanoparticle catalysts derived from single atom sites using hydrothermal method and Manufacturing method of the Same - Google Patents

Abstract

The present invention relates to an electrochemical catalyst using single atomic dots of a noble metal based on a low-temperature hydrothermal synthesis method, a method for manufacturing the same, and a fuel cell including the same, and more specifically, to a platinum single atomic-nanoparticle composite catalyst according to a heat treatment process after supporting platinum single atomic dots on a carbon support through low-temperature hydrothermal synthesis based on an aqueous ethanol solution and a method for manufacturing the same.

Description

Precious metal single atom-nanoparticle catalysts derived from single atom sites using hydrothermal method and Manufacturing method of the Same}

The present invention is an electrochemical catalyst utilizing a noble metal monoatomic point based on a low-temperature hydrothermal synthesis method. It relates to a method for manufacturing the same, and to a fuel cell including the same, and more particularly, to a platinum monoatomic dot according to a heat treatment process after supporting platinum monoatomic dots on a carbon support through low-temperature hydrothermal synthesis based on an aqueous ethanol solution, and a platinum monoatomic-nanoparticle composite catalyst and It relates to a method of manufacturing it.

Single-atom catalysts (SACs) are being actively studied because they can maximize the utilization efficiency of expensive precious metals and exhibit new electrochemical sites different from existing nanoparticle catalysts. For example, single atom Pt supported on carbon nanotubes (CNT) exhibited high activity for chlorine evolution reaction (Nat. Commun. 2020, 11, 412), and single atom supported on TiN and TiC Pt shows excellent selectivity for the H ₂ O ₂ production reaction. However, since single metal atoms are thermodynamically unstable and tend to aggregate with each other to lower surface energy, synthesis is difficult and it is difficult to increase the loading amount of the noble metal to a certain level.

The cation-exchange membrane fuel cell is a next-generation energy conversion system suitable for power sources of automobiles and household power plants due to its high efficiency and high output, low temperature operability, fast start-up and response characteristics. The electrochemical catalyst used as the electrode in the device is a very important factor in determining the reaction rate and energy efficiency. In particular, the oxygen reduction reaction (ORR) generated at the cathode of a polymer electrolyte fuel cell has a slow reaction rate, so a relatively large amount of platinum catalyst is required compared to the anode.

Platinum nano-particle catalysts (Pt/C), which are being used for the cathode electrode of polymer electrolyte fuel cells, are an obstacle to widespread commercialization due to the high price limit of platinum. In particular, in the stack price of the polymer electrolyte fuel cell, the price of the electrode including the catalyst accounts for more than 40% of the total price. Therefore, reducing the amount of platinum used is essential to lower the stack production cost. The type of catalyst used inside the polymer electrolyte fuel cell stack used today is a catalyst (Pt/C) in which platinum nanoparticles are dispersed on a carbon support. In addition to the strategy of improving the activity of platinum by manufacturing platinum in the form of an alloy with a transition metal in order to reduce the amount of platinum used, recently, a strategy of maximizing the use efficiency by improving the dispersion of platinum on a carbon support in an atomic unit This is getting attention.

As a study on the oxygen reduction reaction active site of a platinum single atom catalyst has been reported, the possibility of application to an actual polymer electrolyte fuel cell has been raised (Nat. Commun. 2017, 8, 15938; Angew. Chem. 2019, 131, 1175) ). Platinum monoatomic can act as one active site for oxygen reduction reaction in the carbon support, and thus the utilization efficiency of platinum can be improved up to 100% in theory.

Therefore, in the method for preparing the platinum monoatomic catalyst, there is a need to prevent agglomeration of platinum monoatomic catalysts and to develop a catalyst having a large amount of platinum monoatomic active sites.

Korean Patent No. 1809595 Korean Patent Registration No. 1926354

It is an object of the present invention to provide a catalyst for low platinum oxygen reduction reaction by completely dispersing single atom Pt on a carbon support by a low-temperature ethanol-hydrothermal synthesis method to increase Pt utilization efficiency.

On the one hand, the present invention

(i) preparing a nitrogen-doped carbon support (NBP) through decomposition of carbon nitride;

(ii) mixing the nitrogen-doped carbon support (NBP) with a platinum (Pt) precursor in an aqueous ethanol solution;

(iii) forming platinum (Pt) monoatomic active sites on the surface of the support by maintaining the mixed mixture at 100 to 120° C. for 6 to 12 hours to reduce the platinum precursor (Pt ₁ /NBP); and

(iv) heat-treating the support on which the platinum monoatomic dots are formed to prepare a catalyst (Pt ₁ @Pt/NBP) in which platinum and platinum nanoparticles in the form of single atoms are dispersed; low-temperature hydrothermal synthesis method comprising: Provided is a method for preparing a catalyst for oxygen reduction reaction in a polymer electrolyte fuel cell using a base-based noble metal monoatomic point.

On the other hand, the present invention

nitrogen doped carbon support (NBP); and

Platinum (Pt) dispersed and supported in the form of single atoms and nanoparticles on the support using an ethanol hydrothermal synthesis method; Polymer electrolyte fuel cell oxygen using a noble metal monoatomic point based on a low temperature hydrothermal synthesis method A catalyst for a reduction reaction is provided.

Platinum monoatomic-nanoparticle catalyst according to the present invention significantly lowers the amount of expensive noble metals, and at the same time shows excellent activity and durability for oxygen reduction reaction corresponding to existing platinum nanoparticle catalysts even with a very small amount of platinum, It can be applied to the cathode electrode of polymer electrolyte membrane fuel cells (PEMFCs).

1 shows a HAADF-STEM image of a catalyst according to an embodiment of the present invention (5 wt% Pt, (a) Pt ₁ /NBP, (b) Pt ₁ @Pt/NBP, (c) Pt ₁ / BP, (d) Pt ₁ @Pt/BP)
2 shows a low magnification HAADF-STEM image of a catalyst according to an embodiment of the present invention and a size distribution of platinum nanoparticles (5 wt% Pt, Pt ₁ @Pt/NBP, Pt ₁ @Pt/BP)
Figure 3 shows the oxygen reduction reaction evaluation polarization curve of the catalyst according to an embodiment of the present invention (NBP, Pt ₁ /BP, Pt ₁ /NBP, Pt ₁ @Pt/BP, Pt ₁ @Pt/NBP and commercial Pt/C catalyst)
Figure 4 shows the accelerated durability test (ADT), oxygen reduction reaction evaluation polarization curve after 10,000 cycles of a catalyst according to an embodiment of the present invention ((a) Pt ₁ @Pt/NBP and (b) ) commercial Pt/C catalyst)
5 shows the hydrogen peroxide selectivity for the oxygen reduction reaction product for the catalyst according to an embodiment of the present invention (Pt ₁ /NBP, Pt ₁ @Pt/NBP, Pt ₁ /BP, Pt ₁ @Pt/BP and commercial Pt/C catalyst)
6 shows the EXAFS analysis results of the catalyst according to an embodiment of the present invention (Pt foil, Pt ₁ /NBP, Pt ₁ @Pt/NBP, Pt ₁ /BP, Pt ₁ @Pt/BP and PtO ₂ )
7 shows a polymer electrolyte fuel cell (PEMFC) IV analysis result for a catalyst according to an embodiment of the present invention (Pt ₁ @Pt/NBP and a commercial Pt/C catalyst)

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

One embodiment of the present invention relates to a method for producing a catalyst for oxygen reduction reaction of a polymer electrolyte fuel cell using a noble metal monoatomic point based on a low-temperature hydrothermal synthesis method,

(i) preparing a nitrogen-doped carbon support (NBP) through decomposition of carbon nitride;

(ii) mixing the nitrogen-doped carbon support (NBP) with a platinum (Pt) precursor in an aqueous ethanol solution;

(iii) forming platinum (Pt) monoatomic active sites on the surface of the support by maintaining the mixed mixture at 100 to 120° C. for 6 to 12 hours to reduce the platinum precursor (Pt ₁ /NBP); and

(iv) heat-treating the support on which the platinum monoatomic dots are formed to prepare a catalyst (Pt ₁ @Pt/NBP) in which platinum and platinum nanoparticles in a single atom are dispersed;

In the present invention, when oxygen in the polymer electrolyte fuel cell is reduced, when two electrons are reduced, hydrogen peroxide is produced, and when four electrons are reduced, water is produced. It is known that the generation of hydrogen peroxide adversely affects the durability of the fuel cell membrane, so it is important for the selectivity to the oxygen reduction reaction to appear as a four-electron reaction in PEMFC driving. As used herein, the term “selectivity” refers to the ratio of oxygen converted to water to reactant oxygen supplied.

According to an embodiment of the present invention, when the same Pt is loaded on carbon, it is confirmed that nitrogen-doped carbon (NBP) is easier to load single-atom Pt than normal carbon (BP) (Fig. see 1). In particular, in the case of single atom Pt loaded on nitrogen-doped carbon (Pt ₁ /NBP), single atom Pt exists in a completely dispersed form without aggregation, whereas in the case of normal carbon (Pt ₁ /BP) ) Pt clusters with a size of about 1 nm are observed. When a high concentration of single-atom Pt is contained, aggregation of single Pt atoms appears to be inevitable during high-temperature heat treatment. For example, when single-atom Pt loaded on nitrogen-doped carbon is subjected to high-temperature heat treatment (Pt ₁ @Pt/NBP), single-atom Pt is still observed and the size of Pt aggregated nanoparticles is as small as 2-3 nm, whereas In the case of high-temperature heat treatment of single atom Pt loaded on normal carbon (Pt ₁ @Pt/BP), it is difficult to observe single atom Pt and the size of Pt aggregated nanoparticles is as large as 5 nm. This may result in a sharp decrease in the utilization efficiency of the Pt catalyst.

Hereinafter, a method for preparing a catalyst for oxygen reduction reaction of a polymer electrolyte fuel cell using a noble metal monoatomic point based on a low-temperature hydrothermal synthesis method of the present invention will be described in detail.

(a) Preparation of nitrogen-doped carbon (NBP) through nitrogen carbon decomposition

First, melamine (C ₃ H ₆ N ₆ ) and black pearl carbon are added to the grinder and mixed. The mixture is heated at a high temperature of 600° C. or higher while flowing an inert gas. In the present invention, heat treatment was performed in an Ar atmosphere. Melamine is slowly decomposed in an environment of 300° C. or higher, and formed carbon nitride (graphitic carbon nitride, GC ₃ N ₄ ) can be completely decomposed at 600° C. or higher to generate a uniform carbon group containing nitrogen.

Black pearl (Black Pearl-2000, BP-2000) is used as the carbon support in step (i) of the present invention, but is not limited thereto.

Carbon supports have excellent electrical conductivity and thus can be used as catalyst supports. Among them, black pearl has the advantage of being much cheaper than other carbon supports such as graphene and carbon nanotubes. In addition, black pearl has a BET surface area of about 1,485 m ² /g, which is more than 7 times larger than the surface area (about 235 m ² /g) of Vulcan-72, which is widely used commercially. This is advantageous in supporting and exposing a single platinum atom serving as an active site of the oxygen reduction reaction, thereby enabling superior catalytic activity.

The nitrogen is doped on the carbon support to serve as an anchor of single-atom platinum, thereby preventing aggregation of the platinum and dispersing and forming a large amount of platinum monoatomic active points on the carbon support surface. do

In one embodiment of the present invention, the amount of platinum supported may be included in an amount of 0.5 to 8.0% by weight based on 100% by weight of the total weight of the support and the platinum catalyst.

In step (ii), high-density platinum may be supported in the form of a single atom by controlling the concentration of the platinum precursor. If the above range is not satisfied, if the amount of platinum supported is lower than 0.5 wt %, the active point of the oxygen reduction reaction is very small, and the catalytic activity for the oxygen reduction reaction does not reach that of the existing platinum nanoparticle catalyst. For example, in Nature communications. 8:15938, about 5% by weight of a platinum single atom catalyst is not as active as a commercially available platinum nanoparticle catalyst. If the supported amount of platinum is higher than 8.0 wt %, platinum nanoclusters or platinum nanoparticles may be formed in the low-temperature-ethanol hydrothermal synthesis method, thereby reducing the platinum utilization efficiency and increasing the price of the catalyst. Since the present invention is to exhibit high catalytic activity by using a small amount of platinum, platinum support in a high range does not correspond to the overall direction of the invention.

In one embodiment of the present invention, the content of the doped nitrogen is preferably 2 to 3% by weight based on 100% by weight of the total carbon support.

(b) mixing of platinum precursors

Then, the resultant of step (a) is dispersed in an aqueous ethanol solution. Then, a platinum precursor dissolved in an organic solvent is added and mixed sufficiently with an ultrasonic disperser and a stirrer.

The present invention is characterized by using a low-temperature ethanol hydrothermal synthesis method. During the synthesis process, platinum ions (Pt ²⁺ ) in solution are reduced to individual platinum single atoms (Pt ⁰ ) by a reducing agent, and platinum single atoms (Pt ⁰ ) aggregate with each other to form platinum nanoparticles. have the character to The reducing ability of the reducing agent is high, and the higher the temperature of the solution, the faster individual platinum single atoms (Pt ⁰ ) aggregate into platinum nanoparticles. Therefore, in order to avoid aggregation into platinum nanoparticles and to implement high-density platinum single atoms, it is important to select an appropriate reducing agent and maintain an appropriate temperature.

In the present invention, ethanol acts as a very weak reducing agent, and the reducing power of ethanol can be controlled by the temperature of the solution, so that a high-density platinum single atom can be realized through selection of an appropriate synthesis temperature.

As the platinum precursor, platinic acid hexahydrate (H ₂ PtCl ₆ 6H ₂ O,H ₂ PtCl ₆ ), platinum (II) acetylacetonate (Pt(acac) ₂ ), potassium tetrachloroplatinate (K ₂ PtCl ₄ ) , hydrogen hexachloroplatinate (H ₂ PtCl ₄ ), platinum(II) chloride (PtCl ₂ ), Na ₂ PtCl ₄ 6H ₂ O, and mixtures thereof may be used, but are not limited thereto, and platinum(II) Preference is given to using acetylacetonate.

In one embodiment of the present invention, as the organic solvent, a platinum precursor can be completely dissolved and a solvent that can be completely dissolved in an aqueous ethanol solution can be used, and acetone is preferable, but not limited thereto.

(c) single atom platinum deposition following platinum precursor reduction

After transferring the result of step (b) to a Teflon-sealed autoclave, the platinum precursor is reduced by maintaining it at 100 to 120° C. in a convection oven for 6 to 12 hours. Atomic platinum can be obtained. Here, ethanol acts as a weak reductant to partially reduce Pt ²⁺ of the platinum precursor to Pt ⁰ .

(d) platinum single atom-nanoparticle catalyst synthesis

The resultant of step (c) is filtered and sufficiently dried in a vacuum oven at 50° C. to obtain a sample. A physical mixing process is performed by adding melamine to the sample. This is to increase the number of bonds between nitrogen and platinum single atoms, thereby reducing the unavoidable aggregation of platinum nanoparticles during the heat treatment process. Heat treatment can be performed by flowing argon for a certain time at a high temperature (800 - 1,000 ℃).

One embodiment of the present invention relates to a catalyst for oxygen reduction reaction of a polymer electrolyte fuel cell using a noble metal monoatomic point based on a low-temperature hydrothermal synthesis method,

nitrogen doped carbon support (NBP); and

Platinum (Pt) dispersed and supported in the form of single atoms and nanoparticles on the support by using an ethanol hydrothermal synthesis method; characterized in that it comprises.

One embodiment of the present invention relates to a membrane-electrode assembly for a polymer electrolyte fuel cell using a catalyst (Pt ₁ @Pt/NBP) in which platinum and platinum nanoparticles in the form of single atoms are dispersed on the carbon support,

(i) preparing a catalyst ink including a catalyst (Pt ₁ @Pt/NBP) in which platinum and platinum nanoparticles in the form of a single atom are dispersed on the carbon support and a Pt/C catalyst; and

(ii) coating the catalyst ink on the electrolyte membrane to prepare a membrane-electrode assembly;

As a constituent material of the catalyst ink, perfluorosulfonic acid (Perfluorosulfonic acid, PFSA, C _n F _(2n+1) SO ₃ H) solution, Nafion ^® solution, Aquivion ^® solution, isopropyl Alcohol (IPA, C ₃ H ₇ OH), distilled water (DI water, H ₂ O), normal propyl alcohol (nPA, C ₃ H ₇ OH), acetone (C ₃ H ₆ O), and mixtures thereof may be used, However, the present invention is not limited thereto. In one embodiment of the present invention, the catalyst ink constituent is preferably Nafion solution or isopropyl alcohol.

As the electrolyte membrane, Nafion 211 (Nafion ^® 211), Nafion 212 (Nafion ^® 212), Nafion 115 (Nafion ^® 115), Nafion 117 (Nafion ^® 117) and perfluorosulfonic acid (PFSA) A hydrogen ion conductive polymer electrolyte membrane including, but not limited to, may be used. In one embodiment of the present invention, it is preferable to use Nafion 212 as the electrolyte membrane.

One embodiment of the present invention relates to a fuel cell including the membrane-electrode assembly.

Hereinafter, the present invention will be described in more detail by way of Examples. These examples are only for illustrating the present invention, and it is apparent to those skilled in the art that the scope of the present invention is not limited to these examples.

Example 1:

200 mg of black pearl (BP-2000) carbon and 2 g of melamine (C ₃ H ₆ N ₆ ) were physically mixed in a grinder. Then, it was put in a furnace (furnace) and heat-treated at 650 °C for 1 hour in an argon atmosphere.

Platinum loading was performed using an ethanol hydrothermal reduction method. 25 mg of nitrogen-doped carbon (NBP) was dispersed in 50 mL of an aqueous ethanol solution. Thereafter, the precursor concentrate obtained by dissolving the metal precursor in acetone was extracted as much as the desired amount of platinum and mixed with the above aqueous ethanol solution. For complete mixing, ultrasonication and stirring were performed for 1 hour. The well-mixed mixture was transferred to a Teflon-sealed autoclave, and was then maintained in a convection oven at 100° C. for 6 hours for reduction treatment.

The sample in the naturally cooled autoclave was washed twice with distilled water, and then dried in a vacuum oven at 50°C. After adding melamine to the obtained Pt ₁ /NBP sample and physically mixing it, it was heat-treated while flowing argon at a high temperature (800 - 1,000° C.) in a furnace for 1 hour to prepare a Pt ₁ @Pt/NBP catalyst.

Comparative Example 1:

In Example 1, Pt ₁ /BP and Pt ₁ @Pt/BP catalysts were synthesized in the same manner as in Example 1 on a normal carbon (BP) support instead of nitrogen-doped carbon (NBP).

Experimental Example 1:

Half-cell electrochemical analysis was performed by a three-electrode method. A 1M KCl Ag/AgCl electrode was used as a reference electrode, and a platinum wire was used as a counter electrode. The temperature of the measuring cell was maintained at 25°C. Voltage was expressed based on a reversible hydrogen electrode. For ink preparation, 5 mg of the prepared catalyst was dispersed in 50 μL of 5% Nafion solution, 950 μL of isopropyl alcohol (IPA) through ultrasonication. The catalyst ink was supported on glassy carbon of a rotating ring disc electrode (RRDE), and this was used as a working electrode. As the electrolyte, 0.1 M perchloric acid (HClO ₄ ) aqueous solution was used.

A half-cell catalyst durability analysis was performed according to an accelerated durability test (ADT) protocol. 10,000 repetitions were performed at a scan rate of 100 mV/s in a voltage range of 0.5 - 1.1 V _RHE cycles.

The single cell catalyst analysis was performed by fabricating a membrane-electrode assembly using a hand spray method. 8.0 mg of the synthesized Pt ₁ @Pt/NBP catalyst was dispersed in 148.5 uL of 5% Nafion solution, 1.600 mL of isopropyl alcohol through ultrasonication. This was coated on Nafion 212 heated to 80° C. by spraying on an area of 5 cm ² to prepare a cathode electrode having a loading amount of 0.045 mg _Pt / cm ² . To fabricate the anode electrode, 5.5 mg of a commercial Pt/C catalyst was dispersed in 57.3 uL of 5% Nafion solution, 1.100 mL of isopropyl alcohol through ultrasonication. An anode electrode was manufactured by coating an area of 5 cm ² by spraying on the opposite surface of the Nafion 212 film coated with the cathode electrode. For comparison, a membrane-electrode assembly using commercial Pt/C as a cathode and an anode electrode was prepared in the same manner. At this time, the platinum loading of the cathode is 0.13 mg _Pt /cm ² .

A gas diffusion layer (GDL), a gasket, a current collector, and a bipolar plate were attached to the anode and cathode electrodes, respectively, centering on the fabricated membrane-electrode assembly. The manufactured unit cell was fastened to 100 inch-pounds (in-lb).

In the unit cell test, hydrogen and oxygen were humidified to 100% relative humidity, respectively, and injected into the anode and the cathode, and the backpressure was 0.5 bar, respectively. The operating temperature was 65 ℃, the current was increased from 0 A to 13 A, and the voltage was measured.

The HAADF-STEM image result of 5 wt% Pt ₁ /NBP obtained in Example 1 is shown in FIG. 1 (a). In HAADF-STEM analysis, atoms with high atomic numbers appear bright, so platinum (atomic number: 78) is observed as a bright spot compared to carbon (atomic number: 6) or nitrogen (atomic number: 7). As shown in Fig. 1 (a), it was confirmed that the platinum atom was well supported in the form of a single atom on nitrogen-doped carbon (NBP). The HAADF-STEM image result of the Pt ₁ @Pt/NBP sample obtained by high-temperature heat treatment of Pt ₁ /NBP is shown in FIG. 1 (b). Several agglomerated Pt nanoparticles were observed by the high-temperature heat treatment process. Through high-magnification TEM, it was confirmed that the Pt (111) structure of the face-centered cubic structure was shown with a spacing between the lattices of the particles of 2.27 Å. In the case of Pt ₁ @Pt/NBP, Pt nanoparticles with a size of 2-3 nm were identified along with well-dispersed Pt single atoms.

For comparison, 5 wt% Pt1/BP and Pt ₁ @Pt/BP HAADF-STEM image results obtained using normal carbon (BP) without nitrogen in Preparation Example 1 as a support are shown in FIGS. 1 (c), (d), respectively. ) is shown. In the case of Pt ₁ /BP, aggregation of some Pt atoms was found even before high-temperature heat treatment. In the case of Pt ₁ @Pt/BP, it was difficult to observe a single Pt atom with the naked eye, and Pt nanoparticles with a size of 4 nm were observed. This is because nitrogen (N) acts as an anchor of a single Pt atom to prevent aggregation of Pt.

Low-magnification TEM images and nanoparticle size distributions of Pt ₁ @Pt/NBP and Pt ₁ @Pt/BP are shown in FIG. 2 . In the case of the nitrogen-doped carbon (NBP) of Example 1, the platinum nanoparticles had an average size distribution of 2.49 nm, whereas it was confirmed that the normal carbon (BP) without nitrogen of Comparative Example 1 had a size distribution of 3.67 nm.

The electrochemical oxygen reduction reaction polarization evaluation curve was confirmed (FIG. 3). In the case of Pt ₁ /NBP and Pt ₁ /BP, almost no activity was shown for the 4-electron oxygen reduction reaction. When the formation of platinum nanoparticles and changes in the bonding structure of single-atom platinum occur through high-temperature heat treatment, it is confirmed that the 4-electron oxygen reduction activity is greatly increased in Pt ₁ @Pt/BP and Pt ₁ @Pt/NBP. In particular, Pt ₁ @Pt/NBP had a half-wave potential value (E _1/2 , half-wave potential) of 0.867 V _RHE , confirming that it was higher than the half-wave potential value of 0.859 V _RHE of a commercial Pt/C catalyst. This has high platinum utilization efficiency due to the dispersed single atom Pt, and it can be said that the oxygen reduction activity of platinum was measured to be high.

The electrochemical durability of the synthesized Pt ₁ @Pt/NBP catalyst was confirmed ( FIG. 4 ). In the case of Pt ₁ @Pt/NBP, the half-wave potential change after 10,000 cycles is 9 mV, which is small compared to the half-wave potential change value of 32 mV of commercial Pt/C. Confirmed.

Oxygen reduction reaction produces hydrogen peroxide or water as a product depending on the number of electrons participating in the reaction. The generation of hydrogen peroxide was confirmed through the electrochemical oxygen reduction reaction RRDE analysis (FIG. 5). In Pt ₁ /BP and Pt ₁ /NBP where platinum exists only in the form of a single atom, it was confirmed that the hydrogen peroxide production rate was 25% or more, and two-electron reactions were mixed. When the formation of platinum nanoparticles and the change of the bonding structure of single-atom platinum occur through high-temperature heat treatment, the hydrogen peroxide production rate in Pt ₁ @Pt/BP and Pt ₁ @Pt/NBP was less than 5%, which was It was confirmed that the selectivity increased.

The results of the extended X-ray microstructure (EXAFS) in each region of Pt L for the synthesized catalysts and references are shown in FIG. 6 . Signals appearing around 2.5 Å are signals from Pt-Pt, and by observing that no signals were observed in the case of Pt ₁ /BP and Pt ₁ /NBP, it was confirmed that Pt is well dispersed in the form of single atoms. In addition, in the case of Pt ₁ @Pt/NBP, by observing that the signal at 2.5 Å was smaller than that of Pt ₁ @Pt/BP, it was reconfirmed that nitrogen of the carbon carrier had a positive effect on the distribution of platinum single atoms.

FIG. 7 shows the evaluation results of a unit cell using Pt ₁ @Pt/NBP and a commercial Pt/C catalyst as cathode electrodes, respectively. A unit cell using a membrane-electrode assembly prepared using a commercial Pt/C catalyst as a cathode had a platinum loading of 0.13 mg _Pt /cm ² per unit area, and a Pt ₁ @Pt/NBP (0.045 mg _Pt /cm ² ) About three times as much platinum was used. When the current density at a voltage of 0.9 V was compared, Pt ₁ @Pt/NBP showed 6.0 mA/cm ² , and commercial Pt/C catalyst showed 2.2 mA/cm ² . This is shown as an internal graph of FIG. 7 . Accordingly, it was confirmed that the Pt ₁ @Pt/NBP synthesized in the present invention can obtain 2.7 times the current density at 0.9 V while using only 34% of the platinum amount compared to the commercial Pt/C.

As the specific part of the present invention has been described in detail above, for those of ordinary skill in the art to which the present invention pertains, it is clear that these specific techniques are only preferred embodiments, and the scope of the present invention is not limited thereto. Do. Those of ordinary skill in the art to which the present invention pertains will be able to make various applications and modifications within the scope of the present invention based on the above contents.

Accordingly, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Claims (8)

(i) preparing a nitrogen-doped carbon support (NBP) through decomposition of carbon nitride;
(ii) mixing the nitrogen-doped carbon support (NBP) with a platinum (Pt) precursor in an aqueous ethanol solution;
(iii) forming platinum (Pt) monoatomic active sites on the surface of the support by maintaining the mixed mixture at 100 to 120° C. for 6 to 12 hours to reduce the platinum precursor (Pt ₁ /NBP); and
(iv) heat-treating the support on which the platinum monoatomic dots are formed to prepare a catalyst (Pt ₁ @Pt/NBP) in which platinum and platinum nanoparticles in the form of single atoms are dispersed; low-temperature hydrothermal synthesis method comprising: A method of manufacturing a catalyst for oxygen reduction reaction of a polymer electrolyte fuel cell using a base-based noble metal monoatomic point. The method of claim 1, wherein the carbon support is a black pearl carbon support. The polymer electrolyte fuel cell according to claim 1, wherein the amount of platinum supported is 0.5 to 8.0% by weight based on 100% by weight of the entire support and platinum catalyst. A method for preparing a catalyst for oxygen reduction reaction. The method according to claim 1, wherein the heat treatment is performed at 800 to 1,000 °C, wherein the durability is improved by ammonium chloride treatment. nitrogen doped carbon support (NBP); and
Platinum (Pt) dispersed and supported in the form of single atoms and nanoparticles on the support using an ethanol hydrothermal synthesis method; Polymer electrolyte fuel cell oxygen using a noble metal monoatomic point based on a low-temperature hydrothermal synthesis method Catalyst for reduction reaction. [Claim 6] The polymer electrolyte fuel cell according to claim 5, wherein the amount of platinum supported is 0.5 to 8.0% by weight based on 100% by weight of the entire support and platinum catalyst. Catalyst for oxygen reduction reaction. (i) preparing a catalyst ink comprising the catalyst according to claim 5 and a Pt/C catalyst; and
(ii) coating the catalyst ink on the electrolyte membrane to prepare a membrane-electrode assembly; A fuel cell comprising the membrane-electrode assembly according to claim 7 .

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