Ternary alloy catalysts and methods of making the ternary alloy catalysts

Abstract

The invention provides a ternary alloy catalyst and a method of making the ternary alloy catalyst, the method comprising irradiating a precursor mixture comprising a noble metal precursor, a first transition metal precursor, a second transition metal precursor, and a support with ultrasound. In particular, the second transition metal precursor is an acetate precursor.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2021-0002306, filed with the Korean Intellectual Property Office on January 8, 2021, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to ternary alloy catalysts for fuel cells and methods for preparing said ternary alloy catalysts. Background Technology

[0004] A fuel cell is a device that directly converts the chemical energy of fuel into electrical energy. Due to its higher efficiency compared to existing internal combustion engines, fuel cells are attracting significant attention as a next-generation energy source due to their high energy density and environmental friendliness.

[0005] Polyelectrolyte fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs) primarily operate at low temperatures of approximately 80°C, thus requiring electrode catalysts to enhance the redox reaction rates. Platinum is particularly well-suited as the primary electrode catalyst for fuel cells because it is the only catalyst capable of promoting the oxidation of fuels (hydrogen or alcohol) and the reduction of oxygen from room temperature to approximately 100°C. However, due to the limited availability and high cost of platinum, minimizing the amount of platinum used or maximizing the catalytic activity per unit mass is crucial for the commercialization of fuel cells.

[0006] To achieve the above objectives, platinum alloy catalysts have been studied. For example, due to the electrical and structural properties of the particle surface, platinum alloy catalysts theoretically possess higher activity and stability than pure platinum catalysts, and therefore have attracted attention as a reliable alternative to fuel cell electrode materials.

[0007] However, platinum alloy catalysts suffer from reduced durability and catalytic activity due to the presence of a large amount of unalloyed transition metals on the particle surface during catalyst slurry preparation at pH less than or equal to 1 and under acidic operating conditions of fuel cells. Summary of the Invention

[0008] In a preferred aspect, a method for preparing a ternary alloy catalyst is provided, which improves durability and catalytic activity by preventing phase separation of the alloy-forming particles and improves the elution of metal components in the alloy catalyst.

[0009] In a preferred aspect, a ternary alloy catalyst prepared by means of a method for preparing a ternary alloy catalyst is provided.

[0010] In one aspect, a method for preparing a ternary alloy catalyst is provided, the method comprising treating a precursor mixture comprising a noble metal precursor, a first transition metal precursor, and a second transition metal precursor, wherein the second transition metal precursor is an acetate precursor. The precursor mixture may also suitably contain a support. In some embodiments, the precursor mixture is treated with ultrasound.

[0011] In one aspect, a method for preparing a ternary alloy catalyst is provided. The method may include irradiating a precursor mixture comprising a noble metal precursor, a first transition metal precursor, a second transition metal precursor, and a support with ultrasound. In particular, the second transition metal precursor may be an acetate precursor.

[0012] Precious metals may include one or more selected from platinum (Pt), ruthenium (Ru), osmium (Os), iridium (Ir), palladium (Pd), and their alloys.

[0013] Precious metal precursors may include one or more nitrates, sulfates, acetates, chlorides, oxides, and acetylacetonates selected from precious metals.

[0014] The first transition metal and the second transition metal can be different transition metals.

[0015] The first or second transition metal may include one or more selected from cobalt (Co), iron (Fe), nickel (Ni), zinc (Zn), tin (Sn), manganese (Mn), copper (Cu), scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), zirconium (Zr), yttrium (Y), niobium (Nb), lanthanum (La), and their alloys.

[0016] The first transition metal precursor may include one or more nitrates, sulfates, acetates, chlorides, oxides, and acetylacetonates selected from the first transition metal.

[0017] The carrier may include one or more selected from carbon black, graphite, carbon nanofibers, graphitized carbon nanofibers, carbon nanotubes, carbon nanohorns, and carbon nanowires.

[0018] When irradiated with ultrasound, core-shell particles containing a transition metal oxide coating can be formed.

[0019] The core-shell particle may comprise a transition metal core, a shell, and a transition metal oxide coating. The transition metal core comprises a first transition metal and a second transition metal. The shell surrounds the transition metal core and comprises a noble metal. The transition metal oxide coating surrounds the shell and comprises an oxide of the first transition metal and an oxide of the second transition metal.

[0020] The thickness of the transition metal oxide coating can be from about 0.2 nm to about 0.88 nm.

[0021] Based on 100 mL of precursor mixture, ultrasonic irradiation can be performed for approximately 2 to 6 hours at an output of approximately 100 W to approximately 300 W.

[0022] The method for preparing ternary alloy catalysts may further include annealing core-shell particles to form alloy particles containing a transition metal oxide coating, and removing the transition metal oxide coating from the alloy particles.

[0023] Each alloy particle may contain an alloy core and a noble metal surface layer. The alloy core contains an alloy of a first transition metal and a second transition metal, and the noble metal surface layer surrounds the alloy core and contains noble metal.

[0024] Annealing can be carried out at a temperature of about 200°C to about 400°C for about 0.5 hours to about 16 hours.

[0025] Transition metal oxide coatings can be removed from alloy particles by acid treatment.

[0026] In one aspect, a ternary alloy catalyst is provided, the ternary alloy catalyst comprising an alloy core and a noble metal surface layer, the alloy core comprising an alloy of a first transition metal and a second transition metal, and the noble metal surface layer comprising a noble metal and surrounding the alloy core.

[0027] In ternary alloy catalysts, the atomic ratio of the noble metal, the first transition metal, and the second transition metal can be approximately 1:0.8 to 0.2:0.2 to 0.8.

[0028] The methods for preparing ternary alloy catalysts according to various exemplary embodiments can improve durability and catalytic activity by preventing phase separation of the alloy-forming particles and improve the elution phenomenon of metal components in the alloy catalyst.

[0029] Other aspects of the invention are disclosed below. Attached Figure Description

[0030] Figure 1 An exemplary method for preparing a ternary alloy catalyst according to an exemplary embodiment of the present invention is shown.

[0031] Figure 2 A graph showing the in-situ XRD analysis results of the binary alloy catalyst prepared in Reference Example 1 and the ternary alloy catalyst prepared in Comparative Example 1.

[0032] Figure 3The graphs show the in-situ XRD analysis results of the binary alloy catalyst prepared in Reference Example 1 and the ternary alloy catalysts prepared in Examples 1 to 3.

[0033] Figure 4 Transmission electron microscope (TEM) images of the binary alloy catalyst prepared for reference Example 1 and the ternary alloy catalysts prepared for Examples 1 to 3.

[0034] Figure 5 and Figure 6 The graphs show the measurement results of the performance of the binary alloy catalyst prepared in Reference Example 1 and the ternary alloy catalysts prepared in Examples 1 to 3.

[0035] Figures 7 to 10 The graphs show the measurement results of the durability of the binary alloy catalyst prepared in Reference Example 1 and the ternary alloy catalysts prepared in Examples 1 to 3, respectively.

[0036] <Description of reference numerals>

[0037] 10: Precursor Mixture

[0038] 20: Core-shell particles

[0039] 30: Ternary alloy catalyst

[0040] 110: Transition Metal Core

[0041] 120: Precious metal casing

[0042] 130: Alloy particles

[0043] 150: Transition metal oxide coating

[0044] 210: Alloy Core

[0045] 220: Precious metal casing Detailed Implementation

[0046] The advantages and features of this application, as well as its implementation methods, will become apparent from the embodiments described below with reference to the accompanying drawings. However, the embodiments should not be construed as limiting oneself to those described herein. Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art. Furthermore, unless explicitly defined, the meanings defined in commonly used dictionaries should not be ideally or excessively interpreted. Moreover, unless explicitly stated to the contrary, the terms "comprising" and variations such as "including" or "containing" should be understood to imply inclusion of the stated elements but not exclusion of any other elements.

[0047] Unless otherwise stated, all figures, values ​​and / or expressions used herein relating to component quantities, reaction conditions, polymer compositions and formulas should be understood to be modified in all cases by the term “about”, as these figures are approximations in nature and particularly reflect the various measurement uncertainties encountered in obtaining these values.

[0048] Furthermore, unless otherwise stated or obvious from the context, the term "about" as used herein should be understood to mean within the normal tolerance range in the field, for example, within 2 average standard deviations. "About" can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the specified value. All numerical values ​​provided herein are modified by the term "about" unless obvious from the context.

[0049] Furthermore, if a range of values ​​is disclosed herein, unless otherwise stated, the range is continuous and includes every value from the minimum to the maximum (inclusive) of the range. Additionally, if the range involves integers, unless otherwise stated, it includes every integer from the minimum to the maximum (inclusive).

[0050] Furthermore, unless otherwise stated, the singular includes the plural.

[0051] The method for preparing ternary alloy catalysts includes irradiating a precursor mixture containing a noble metal precursor, a first transition metal precursor, a second transition metal precursor, and a support with ultrasound.

[0052] Figure 1 This is a schematic diagram illustrating a method for preparing a ternary alloy catalyst according to an embodiment. For example, a method for preparing a ternary alloy catalyst is described.

[0053] When a precursor mixture 10 containing a noble metal precursor, a first transition metal precursor, a second transition metal precursor, and a carrier is irradiated with ultrasound, core-shell particles 20 containing a transition metal oxide coating 150 can be formed (S1).

[0054] The high-frequency oscillations of ultrasound can generate bubbles within a cavity, leading to oscillation growth. When the oscillations eventually reach a certain level, the cavity may explode. This series of processes caused by ultrasound irradiation is known as the "acoustic cavitation mechanism."

[0055] The cavity explosion that occurs in the final stage of the acoustic cavitation mechanism can generate a large amount of heat energy up to about 5000K, which will last for about 10 seconds. -6 It dissipates in an extremely short time, within seconds.

[0056] When the reactants in a chemical reaction involving ultrasonic irradiation are at least two materials with different vapor pressures, the evaporation rates of the bubbles generated by the high-frequency oscillation of ultrasound may differ, allowing for the control of the structural and electrochemical properties of the reaction products. For example, when preparing nanoparticles containing at least two metals by using noble metal precursors and transition metal precursors as reactants and irradiating them with ultrasound, the distribution of noble metal elements and transition metal elements in the nanoparticles can be controlled based on the vapor pressure difference between the noble metal precursors and transition metal precursors.

[0057] For example, in nanoparticles, noble metals with low vapor pressure can be distributed in the outer shell portion, and transition metals with high vapor pressure can be distributed in the core portion, thereby forming core-shell particles 20.

[0058] Based on approximately 100 mL of precursor mixture 10, ultrasonic irradiation can be performed for approximately 2 to approximately 6 hours at an output of approximately 100 W to approximately 300 W. When ultrasonic irradiation is performed at an output of less than approximately 100 W or for less than approximately 2 hours, the metal ions may be insufficiently reduced, while when performed at an output of more than approximately 300 W or for more than approximately 6 hours, the particles may grow to an undesirable size.

[0059] Ultrasonic irradiation can be performed at temperatures ranging from approximately 130°C to approximately 180°C. When ultrasonic irradiation is performed at temperatures below approximately 130°C, metal ions may not be reduced sufficiently, while when performed at temperatures above approximately 180°C, particles may grow to an undesirable size.

[0060] Noble metals may include one or more selected from platinum (Pt), ruthenium (Ru), osmium (Os), iridium (Ir), palladium (Pd), and their alloys. The vapor pressure of the noble metal precursor may be lower than that of the transition metal precursor, and it may promote the electrodisplacement reaction after the formation and size increase of transition metal seed particles. For example, the noble metal precursor may be in the form of a noble metal salt and may include nitrates, sulfates, acetates, chlorides, oxides, or combinations thereof. In particular, the noble metal precursor may include acetylacetonates, hexafluoroacetylacetonates, or pentafluoroacetylacetonates of the noble metal.

[0061] The transition metals include a first transition metal and a second transition metal, and the first transition metal and the second transition metal can be different transition metals.

[0062] The first or second transition metal may include one or more selected from cobalt (Co), iron (Fe), nickel (Ni), zinc (Zn), tin (Sn), manganese (Mn), copper (Cu), scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), zirconium (Zr), yttrium (Y), niobium (Nb), lanthanum (La), and their alloys.

[0063] Meanwhile, the second transition metal can be a transition metal that can improve the elution phenomenon of the first transition metal. In other words, when the alloy catalyst contains only a noble metal and the first transition metal, the first transition metal may be easily eluted during the preparation of the catalyst slurry at pH 1 or lower, or under acidic operating conditions in the fuel cell, thereby reducing durability and catalytic activity. Conversely, when a second transition metal is also included, the elution phenomenon of the first transition metal can be improved.

[0064] For example, the first transition metal may include one or more selected from iron (Fe), cobalt (Co), nickel (Ni), manganese (Mn), chromium (Cr), and their alloys, and the second transition metal may include one or more selected from copper (Cu), zinc (Zn), yttrium (Y), lanthanum (La), ruthenium (Ru), and their alloys. In particular, the first transition metal may be iron (Fe), and the second transition metal may be copper (Cu).

[0065] The first transition metal precursor may be in the form of a first transition metal salt, and may include, for example, nitrates, sulfates, acetates, chlorides, oxides, or combinations thereof. In particular, the first transition metal precursor may be an acetylacetonate of the first transition metal, a hexafluoroacetylacetonate of the first transition metal, or a pentafluoroacetylacetonate of the first transition metal.

[0066] Due to the high vapor pressure, the first transition metal precursor can evaporate rapidly and be trapped in the cavity by ultrasound, thus the transition metal can be located in the core portion of the core-shell particle 20.

[0067] On the other hand, when a ternary alloy catalyst is prepared by ultrasonic synthesis using a second transition metal precursor, the second transition metal precursor may undergo phase separation, thereby forming non-alloyed second transition metal particles.

[0068] To address this issue, the second transition metal precursor can be an acetate precursor. For example, when the second transition metal precursor is a sulfate, due to SO₂... x The high adsorption energy of anions leads to the adsorption and poisoning of sulfates on the catalyst particle surface, potentially reducing catalytic activity. When the second transition metal precursor is a chloride, ClO may form during the ultrasonic reaction. x y- This can damage the ultrasonic device, and when the second transition metal precursor is a nitrate, the alloying rate of the second transition metal may be reduced due to its low dispersibility in organic solvents. Conversely, when the second transition metal precursor is an acetate, these problems do not occur, and because the reactivity (i.e., volatility) of this precursor is lower than that of other precursors, ternary alloys can be formed without phase separation.

[0069] The carrier may include one or more selected from carbon carriers, such as carbon black, graphite, carbon nanofibers, graphitized carbon nanofibers, carbon nanotubes, carbon nanohorns, carbon nanowires, or combinations thereof. Carbon black may include superconducting acetylene black, Ketjen black, acetylene black, channel black, furnace black, lamp black, and thermally cracked black.

[0070] The precursor mixture 10 may also contain a reducing solvent.

[0071] The reducing solvent can be an organic material that does not contain water or oxygen, such as a solvent with reducing ability at a temperature greater than or equal to about 70°C, or a solvent with reducing ability at a temperature from about 70°C to about 400°C. In particular, the reducing solvent may include one or more selected from ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, and glycerol.

[0072] The reducing solvent can reduce one of the reactants of noble metal precursors and transition metal precursors in the cavity formed by ultrasonic treatment, and maintain a high boiling point, thereby creating an external liquid environment for the generation and destruction of the cavity.

[0073] Meanwhile, the surface of the core-shell particles 20 formed by ultrasonic treatment may include a transition metal oxide coating 150 surrounding the noble metal shell 120.

[0074] Due to the insufficient solubility of transition metals in the platinum lattice, the difference in reduction rate, and the proportion of excess transition metals during ultrasonic treatment, a transition metal oxide coating 150 can be formed.

[0075] The thickness of the transition metal oxide coating 150 can be from about 0.2 nm to about 0.88 nm. When the thickness of the transition metal oxide coating 150 is less than about 0.2 nm, the transition metal oxide coating 150 may form a non-uniform and thin thickness, and therefore, the particle size may not be well controlled. When the thickness of the transition metal oxide coating 150 is greater than about 0.88 nm, crystallized transition metal oxides may be generated after the annealing process, leaving residues.

[0076] Since the transition metal oxide coating 150 originates from a transition metal precursor (similar to the transition metal core 110), the transition metal core 110 may contain a first transition metal and a second transition metal, and the transition metal oxide coating 150 may contain an oxide of the first transition metal and an oxide of the second transition metal, therefore, the transition metal oxide coating 150 and the transition metal core 110 may contain the same transition metal.

[0077] The method for preparing the ternary alloy catalyst 30 according to various exemplary embodiments of the present invention can simplify the process and reduce costs by forming core-shell particles 20 containing a transition metal oxide coating 150 in a single process through ultrasonic treatment.

[0078] The method for preparing the ternary alloy catalyst 30 may further include annealing the core-shell particles 20 (S2) and removing the transition metal oxide coating 150 (S3).

[0079] During the annealing (S2) of the core-shell particles 20, alloy particles 130 containing a transition metal oxide coating 150 are formed.

[0080] Specifically, through an annealing process, alloy particles 130 comprising an alloy core and a precious metal surface layer are formed. The alloy core comprises an alloy of a first transition metal and a second transition metal, and the precious metal surface layer comprises a precious metal and surrounds the alloy core.

[0081] Here, since the transition metal oxide coating 150 inhibits particle growth, the alloy particles 130 are controlled to have a size of a few nanometers during the annealing process. Therefore, the high-temperature annealing process can be fully carried out so that the metal atoms are regularly arranged in the alloy, thereby increasing the compositional uniformity and catalytic activity.

[0082] Annealing can be performed at temperatures ranging from approximately 200°C to approximately 400°C. When the annealing temperature is below 200°C, the increase in catalytic activity may be limited due to the lack of improvement in the regular arrangement of metal atoms in the alloy. When the annealing temperature is above approximately 400°C, the effect of inhibiting particle size growth may decrease, leading to a reduction in catalytic activity.

[0083] The annealing process can be carried out in an inert gas atmosphere (e.g., argon, nitrogen) or a mixed gas atmosphere of inert gas and hydrogen (H2) (based on the total volume of the mixed gas, containing about 4% to about 6% hydrogen).

[0084] Finally, the transition metal oxide coating 150 can be removed by acid treatment (S3).

[0085] Acids used for acid treatment may include HClO4, HNO3, HCl, or combinations thereof.

[0086] The concentration of the acid can be from about 0.01 M to about 1.0 M. When the concentration of the acid is less than about 0.01 M, the etching may be insufficient and the acid treatment time may be prolonged, while when the concentration of the acid is greater than about 1.0 M, the platinum may dissolve along with it.

[0087] Acid treatment can be performed at temperatures ranging from approximately 60°C to approximately 94°C for approximately 2 to approximately 4 hours. When the acid treatment temperature is below approximately 60°C or the treatment time is less than 2 hours, etching may be insufficient. When the acid treatment temperature is above approximately 94°C, even with reflow, boiling within the container may be severe, posing safety concerns. Furthermore, when the acid treatment time exceeds approximately 4 hours, the transition metal content remains unchanged, potentially wasting processing time and costs.

[0088] A ternary alloy catalyst 30 prepared by the above-described method for preparing ternary alloy catalysts is also provided.

[0089] The ternary alloy catalyst 30 includes an alloy core 210 and a noble metal surface layer 220. The alloy core 210 includes an alloy of a first transition metal and a second transition metal, and the noble metal surface layer 220 surrounds the alloy core 210 and contains noble metal.

[0090] According to the method for preparing a ternary alloy catalyst 30 according to various exemplary embodiments of the present invention, since the core-shell particles 20 formed by irradiation with ultrasound contain a transition metal in the core, the ternary alloy catalyst 30 formed by annealing has a noble metal surface layer 220, wherein the noble metal particles are exposed on the outer surface of the ternary alloy catalyst 30 and dispersed in the noble metal surface layer 220 at a high density.

[0091] Typically, the slurry preparation process for forming the electrodes is carried out at a pH of less than or equal to about 1. Because fuel cells operate in an acidic atmosphere, transition metals in the alloy catalyst may be easily eluted, and these eluted transition metals can enter the ion exchange membrane, thereby increasing membrane resistance. This can potentially lead to a decrease in fuel cell performance.

[0092] However, since the ternary alloy catalyst 30 prepared by the above-described method for preparing ternary alloy catalysts contains a second transition metal, the elution of the first transition metal can be suppressed.

[0093] The thickness of the noble metal surface layer 220 can be less than or equal to about 0.5 nm, or it can be from about 0.2 nm to about 0.5 nm. When the thickness of the noble metal surface layer 220 is greater than about 0.5 nm, its surface structure is similar to that of existing platinum catalysts, and therefore the performance-enhancing effect produced by the alloy may be lost.

[0094] In the ternary alloy catalyst 30, the atomic ratio of the noble metal, the first transition metal, and the second transition metal can be approximately 1:0.8 to 0.2:0.2 to 0.8. When the atomic ratio of the first transition metal is greater than approximately 0.8, the effect of the second transition metal may be insufficient, while when it is less than approximately 0.2, separation of the second transition metal may occur.

[0095] The particle size of the ternary alloy catalyst 30 can be from about 2 nm to about 20 nm. When the particle size of the ternary alloy catalyst 30 is less than about 2 nm, the durability of the catalyst may be reduced, while when it is greater than about 20 nm, it may be insufficient to ensure the electrochemical specific surface area.

[0096] An electrode for a fuel cell is also provided, the electrode comprising a ternary alloy catalyst 30 and an ionomer mixed with the ternary alloy catalyst 30.

[0097] A membrane electrode assembly is also provided, comprising an anode and a cathode facing each other, and an ion exchange membrane between the anode and the cathode, wherein the anode, cathode, or both are the aforementioned electrodes.

[0098] In addition, a fuel cell including the aforementioned membrane electrode assembly is provided.

[0099] The electrodes, membrane electrode assemblies, and fuel cells are the same as those of general electrodes, membrane electrode assemblies, and fuel cells, except that they include the aforementioned ternary alloy catalyst 30, so its detailed description will be omitted.

[0100] Example

[0101] Specific embodiments of the invention are described below. However, the embodiments described below are for illustrative purposes only, and the scope of the invention is not limited thereto.

[0102] Preparation Example: Preparation of Ternary Alloy Catalysts

[0103] Reference Example 1

[0104] Platinum acetylacetonate (or Pt(acac)2), iron acetylacetonate (or Fe(acac)3), and a porous carbon support (Vulcan Xc72) were added to ethylene glycol to prepare each precursor mixture with the compositions shown in Table 1. 100 mL of each precursor mixture was irradiated for 3 hours under an argon atmosphere using a high-precision ultrasonic transducer (30% amplitude, 13 mm solid-state probe, 20 kHz, Model VC-500 manufactured by Sonic & Materials, Inc.) at 150 W output.

[0105] Subsequently, the obtained particles were annealed at 400°C for 2 hours under an H2 / Ar mixed gas atmosphere to prepare a PtFe / C catalyst.

[0106] Examples 1 to 3

[0107] Each precursor mixture was prepared by adding Pt(acac)2, Fe(acac)3, copper(II) acetate and porous carbon support (Vulcan XC72) to ethylene glycol to have the compositions shown in Table 1, and 100 mL of each precursor mixture was irradiated for 3 hours at 150 W output using a tip-type ultrasonic transducer (30% amplitude, 13 mm solid probe, 20 kHz, Model VC-500 manufactured by Sonic & Materials, Inc.) under an argon atmosphere to form core-shell particles containing a transition metal oxide coating.

[0108] The obtained core-shell particles were annealed at 400°C for 2 hours in an H2 / Ar mixed gas atmosphere to form alloy particles containing a transition metal oxide coating.

[0109] A ternary alloy catalyst was prepared by treating alloy particles with a mixed solution of 0.1M HClO4 and ethanol at 94℃ for 4 hours.

[0110] Comparative Example 1

[0111] The ternary alloy catalyst was prepared according to the same method as in Example 1, except that copper acetylacetonate (or Cu(acac)2) was used instead of copper acetate(II).

[0112] Table 1

[0113]

[0114] Experimental Example 1: XRD and TEM Analysis of Ternary Alloy Catalysts

[0115] In-situ XRD analysis was performed on the binary alloy catalyst (PtFe / C) prepared in Reference Example 1 and the ternary alloy catalyst (PtFeCu / C) prepared in Comparative Example 1. The results showed... Figure 2 middle.

[0116] like Figure 2 As shown, for the PtFeCu ternary alloy catalyst prepared by using Cu(acac)2, part of the Cu phase separates into metallic Cu.

[0117] In addition, in-situ XRD analysis was performed on the binary alloy catalyst (PtFe / C) of Reference Example 1 and the ternary alloy catalysts (PtFeCu / C-1 to PtFeCu / C-3) of Examples 1 to 3, and the results showed that... Figure 3 In the examples 1 to 3, the ternary alloy catalysts did not show metallic Cu, therefore Cu phase separation did not occur.

[0118] Furthermore, transmission electron microscopy (TEM) was used to observe the binary alloy catalyst (PtFe / C) of Reference Example 1 and the ternary alloy catalysts (PtFeCu / C-1 to PtFeCu / C-3) of Examples 1 to 3. The results showed... Figure 4 Regardless of composition, the binary alloy catalyst (PtFe / C) of Reference Example 1 and the ternary alloy catalysts (PtFeCu / C-1 to PtFeCu / C-3) of Examples 1 to 3 all have a size of about 3 nm and are very well dispersed on the carbon support.

[0119] Experimental Example 2: Performance and Durability Analysis of Ternary Alloy Catalysts

[0120] Half-cells were prepared using the binary alloy catalyst (PtFe / C) of Reference Example 1 and the ternary alloy catalysts (PtFeCu / C-1 to PtFeCu / C-3) of Examples 1 to 3, respectively. The performance of the half-cells was then measured, and the results showed... Figure 5 and Figure 6 The results are summarized in Table 2. As a reference, commercially available Pt / C catalysts were used.

[0121] Table 2

[0122]

[0123] Catalytic performance compared to commercially available Pt / C catalysts (0.21 A / mg) Pt Compared to the previous method, the catalytic performance of the PtFe / C binary alloy catalyst was improved by approximately 1.5 times (0.33 A / mg). Pt ), and the performance of the PtFe / C binary alloy catalyst (0.33A / mg) Pt Compared to the previous method, the performance of the PtFeCu / C-1 ternary alloy catalyst prepared by adding a small amount of Cu was improved by approximately two times (0.66 A / mg). Pt Furthermore, as the amount of Cu added increases, the durability is better guaranteed, but the catalytic performance gradually decreases.

[0124] Furthermore, half-cells were fabricated using the binary alloy catalyst (PtFe / C) of Reference Example 1 and the ternary alloy catalysts (PtFeCu / C-1 to PtFeCu / C-3) of Examples 1 to 3. The durability of the half-cells (DOE catalyst AST conditions) was then measured, and the results are shown in [the table / data]. Figures 7 to 10 In particular, durability was assessed by comparing changes in electrochemically active surface area (ΔECSA) and half-wave potential (ΔE1 / 2).

[0125] Figure 7A graph showing the measurement results of the durability of the binary alloy catalyst (PtFe / C) prepared in Reference Example 1, Figure 8 A graph showing the durability of the ternary alloy catalyst (PtFeCu / C-1) prepared in Example 1, Figure 9 A graph showing the measurement results of the durability of the ternary alloy catalyst (PtFeCu / C-2) prepared in Example 2, Figure 10 A graph showing the measurement results of the durability of the ternary alloy catalyst (PtFeCu / C-3) prepared in Example 3.

[0126] like Figures 7 to 10 As shown, compared with the PtFe / C binary alloy catalyst, the PtFeCu / C ternary alloy catalyst prepared by adding Cu has smaller ΔECSA and ΔE1 / 2. In other words, the addition of Cu significantly improves the durability of the alloy catalyst.

[0127] While the invention has been described in conjunction with what are now considered preferred exemplary embodiments, it should be understood that the invention is not limited to the disclosed embodiments, but rather is intended to cover various modifications and equivalents that are greater than or equal to the spirit and scope of the appended claims.

Claims

1. A method for preparing a ternary alloy catalyst, the method comprising: Processing a precursor mixture comprising a noble metal precursor, a first transition metal precursor, and a second transition metal precursor. The second transition metal precursor is an acetate precursor. The precursor mixture is treated with ultrasound. When subjected to ultrasonic irradiation, core-shell particles with a transition metal oxide coating are formed. The core-shell particles comprise: A transition metal core, wherein the transition metal core comprises a first transition metal and a second transition metal. An outer casing surrounding the transition metal core and comprising noble metals, and A transition metal oxide coating, the transition metal oxide coating surrounding the shell and comprising an oxide of a first transition metal and an oxide of a second transition metal.

2. The method for preparing a ternary alloy catalyst according to claim 1, wherein, The precursor mixture includes a carrier.

3. The method for preparing a ternary alloy catalyst according to claim 1, wherein, The precious metals include one or more selected from platinum, ruthenium, osmium, iridium, palladium and their alloys.

4. The method for preparing a ternary alloy catalyst according to claim 1, wherein, The precious metal precursor includes one or more of the following: nitrates, sulfates, acetates, chlorides, oxides, and acetylacetonates of precious metals.

5. The method for preparing a ternary alloy catalyst according to claim 1, wherein, The first transition metal and the second transition metal are different transition metals.

6. The method for preparing a ternary alloy catalyst according to claim 1, wherein, The first or second transition metal includes one or more selected from cobalt, iron, nickel, zinc, tin, manganese, copper, scandium, titanium, vanadium, chromium, zirconium, yttrium, niobium, lanthanum and their alloys.

7. The method for preparing a ternary alloy catalyst according to claim 1, wherein, The first transition metal precursor includes one or more nitrates, sulfates, acetates, chlorides, oxides, and acetylacetonates selected from the first transition metal.

8. The method for preparing a ternary alloy catalyst according to claim 2, wherein, The carrier includes one or more selected from carbon black, graphite, carbon nanofibers, graphitized carbon nanofibers, carbon nanotubes, carbon nanohorns, and carbon nanowires.

9. The method for preparing a ternary alloy catalyst according to claim 1, wherein, The thickness of the transition metal oxide coating is from 0.2 nm to 0.88 nm.

10. The method for preparing a ternary alloy catalyst according to claim 1, wherein, Based on 100 mL of precursor mixture, ultrasonic irradiation was performed for 2 to 6 hours at an output of 100 W to 300 W.

11. The method for preparing a ternary alloy catalyst according to claim 1, the method further comprising: The core-shell particles are annealed to form alloy particles containing a transition metal oxide coating, and Remove the transition metal oxide coating from the alloy particles.

12. The method for preparing a ternary alloy catalyst according to claim 11, wherein, Each alloy particle contains: The alloy core comprises an alloy of a first transition metal and a second transition metal, and A precious metal surface layer, which surrounds the alloy core and contains precious metal.

13. The method for preparing a ternary alloy catalyst according to claim 11, wherein, Annealing is carried out at a temperature of 200°C to 400°C for 0.5 to 16 hours.

14. The method for preparing a ternary alloy catalyst according to claim 11, wherein, The transition metal oxide coating is removed from the alloy particles by acid treatment.

15. A ternary alloy catalyst prepared by the method of claim 1, wherein the ternary alloy catalyst comprises: The alloy core comprises an alloy of a first transition metal and a second transition metal, and A precious metal surface layer, the precious metal surface layer comprising a precious metal and surrounding the alloy core.

16. The ternary alloy catalyst according to claim 15, wherein, In ternary alloy catalysts, the atomic ratio of noble metal, first transition metal and second transition metal is 1:0.8 to 0.2:0.2 to 0.8.

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