Composite body containing active metal particles and sacrificial metal particles, membrane electrode assembly, and fuel cell containing the same

Abstract

The present invention relates to a composite containing active metal particles and sacrificial metal particles, a membrane electrode assembly, and a fuel cell including the same.

Description

Technical Field

[0001] The present invention relates to a composite containing active metal particles and sacrificial metal particles, a membrane electrode assembly, and a fuel cell including the same.

Background Art

[0002] A fuel cell is an electrochemical device that converts chemical energy generated by oxidation / reduction of a fuel into electrical energy and has been attracting attention as an environmentally friendly energy source. The electrode reactions in a fuel cell consist of a hydrogen oxidation reaction (HOR) at the anode and an oxygen reduction reaction (ORR) at the cathode. In order to improve the efficiency of such electrochemical reactions, a catalyst is essentially used. In particular, the oxygen reduction reaction at the cathode is slower than the hydrogen oxidation reaction at the anode, and since its reaction rate determines the performance of the entire fuel cell, noble metal catalysts such as platinum (Pt), palladium (Pd), and gold (Au) are currently mainly used to promote the oxygen reduction reaction at the cathode.

[0003] As an example, Korean Patent Publication No. 10-1484188 discloses a catalyst in which platinum is supported on a carbon support. Such a catalyst attempts to increase the active surface area to reduce the amount of precious metal used in the catalyst and enhance the catalytic activity. However, there is a problem of degradation of the supported platinum nanoparticles, and with the continuous consumption of the high platinum catalyst and the increase in inefficiency, there is a demerit that the catalytic activity and durability decrease. Specifically, such degradation of the platinum nanoparticles occurs because side reactions such as the oxygen reduction reaction at the anode and the platinum oxidation reaction at the cathode occur due to the intrusion of air into the anode. In particular, the oxidized platinum (Pt) particles cannot properly perform the oxygen reduction reaction and can cause dissolution of platinum and Ostwald ripening. This induces aggregation or size growth of the platinum (Pt) particles, reduces the utilization efficiency of the platinum catalyst, and as a result, the performance of the fuel cell decreases due to such degradation of the platinum (Pt) particles.

[0004] As a method for suppressing such a degradation phenomenon, research has been actively conducted on coating the surfaces of active metal particles such as platinum (Pt), palladium (Pd), and gold (Au) with carbon or metal oxides. However, such a coating method has demerits in that it reduces the active sites of the active metal, causes catalyst poisoning due to the generation of unnecessary by-products such as hydrogen peroxide by a two-electron reaction, and reduces the activity and stability of the fuel cell. In addition, the manufacturing process is complicated due to characteristics such as the morphology and surface energy of the catalyst.

[0005] Therefore, in order to provide a fuel cell that maintains the activity of the noble metal-based catalyst and has significantly improved durability, the problem of degradation of the active metal needs to be more fundamentally solved.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Non-Patent Literature

[0007]

Non-Patent Literature 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] One object of the present invention is to provide a composite and a membrane electrode assembly having excellent catalytic activity and significantly improved durability.

[0009] Another object of the present invention is to provide an electrode for a fuel cell including the composite of the present invention.

[0010] Still another object of the present invention is to provide a fuel cell including the electrode for a fuel cell and / or a membrane electrode assembly.

[0011] Still another object of the present invention is to provide a method for manufacturing the composite and the membrane electrode assembly.

Means for Solving the Problems

[0012] The present invention provides a composite, the composite including a carbon support, active metal particles, and sacrificial metal particles that oxidize or reduce instead of the active metal particles, and the active metal particles and the sacrificial metal particles are independently supported on the carbon support.

[0013] In the composite according to the present invention, the active metal particles and the sacrificial metal particles may not form an alloy with each other.

[0014] In the composite according to the present invention, the active metal particles may include one or more metals selected from the group consisting of palladium (Pd), platinum (Pt), gold (Au), ruthenium (Ru), rhodium (Rh), iridium (Ir), osmium (Os), and alloys containing these.

[0015] In the composite according to the present invention, the metal contained in the sacrificial metal particles may have a standard reduction potential lower than that of the metal contained in the active metal particles.

[0016] In the composite according to the present invention, the sacrificial metal particles may include one or more metals selected from the group consisting of silver (Ag), palladium (Pd), iridium (Ir), ruthenium (Ru), rhodium (Rh), platinum (Pt), osmium (Os), iron (Fe), aluminum (Al), and alloys containing these.

[0017] In the composite according to the present invention, the ratio (D2 / D1) of the average particle diameter (D2) of the active metal particles after 30,000 cycles of the accelerated durability test of the composite to the average particle diameter (D1) of the active metal particles before the accelerated durability test may be 3 or less.

[0018] In the composite according to the present invention, the atomic ratio of the sacrificial metal contained in the sacrificial metal particles to the active metal contained in the active metal particles may be 1:0.1 to 1:50.

[0019] In the composite according to the present invention, the active metal contained in the active metal particles includes platinum (Pt), and the difference in the 2θ value of the maximum peak appearing in the range of 2θ = 39.8 ± 1.0° in the X-ray diffraction (XRD) spectra of the composite and pure platinum (Pt) may be 0.3° or less.

[0020] In the composite according to the present invention, the active metal contained in the active metal particles includes platinum (Pt), and Pt 4f by X-ray photoelectron spectroscopy (XPS) of the composite 7 / 2 The ratio (I0 / I II ) of the Pt(0) peak intensity (I0) to the Pt(II) peak intensity (III ) may be 1.8 or more.

[0021] The present invention provides a method for producing a composite. The method for producing the composite includes: mixing a dispersion containing a carbon support carrying active metal particles and a solution containing a sacrificial metal precursor to produce a first reaction solution; and adding a reducing agent to the first reaction solution to synthesize a composite in which the active metal particles and the sacrificial metal particles are independently carried on the carbon support.

[0022] The present invention provides another method for producing a composite. The other method for producing the composite includes: mixing a dispersion containing a carbon support carrying active metal particles and a dispersion containing a carbon support carrying sacrificial metal particles to produce a second reaction solution; and adding a reducing agent to the second reaction solution to synthesize a composite in which the active metal particles and the sacrificial metal particles are independently carried on the carbon support.

[0023] The present invention provides a membrane electrode assembly, which includes: a cathode including a first catalyst layer and a first gas diffusion layer; an anode including a second catalyst layer and a second gas diffusion layer; and a polymer electrolyte membrane disposed between the cathode and the anode. The first catalyst layer contains active metal particles, and the first gas diffusion layer includes a support for the first gas diffusion layer and sacrificial metal particles carried on the support for the first gas diffusion layer, which oxidize or reduce instead of the active metal particles.

[0024] In the membrane electrode assembly according to the present invention, one surface of the support for the first gas diffusion layer where the sacrificial metal particles are located may face one surface of the first catalyst layer.

[0025] In the membrane electrode assembly according to the present invention, the second catalyst layer may contain active metal particles, and the second gas diffusion layer may include a support for the second gas diffusion layer and sacrificial metal particles carried on the support for the second gas diffusion layer, which oxidize or reduce instead of the active metal particles.

[0026] In the membrane electrode assembly according to the present invention, the active metal particles may include one or more metals selected from the group consisting of palladium (Pd), platinum (Pt), gold (Au), ruthenium (Ru), rhodium (Rh), iridium (Ir), osmium (Os), and alloys containing these metals.

[0027] In the membrane electrode assembly according to the present invention, the metal contained in the sacrificial metal particles may have a standard reduction potential lower than that of the metal contained in the active metal particles.

[0028] In the membrane electrode assembly according to the present invention, the sacrificial metal particles may include one or more metals selected from the group consisting of silver (Ag), palladium (Pd), iridium (Ir), ruthenium (Ru), rhodium (Rh), platinum (Pt), osmium (Os), iron (Fe), aluminum (Al), and alloys containing these metals.

[0029] In the membrane electrode assembly according to the present invention, the ratio (D2 / D1) of the average particle diameter (D2) of the active metal particles after 30,000 cycles of the accelerated durability test to the average particle diameter (D1) of the active metal particles before the accelerated durability test may be 3 or less.

[0030] In the membrane electrode assembly according to the present invention, the atomic ratio of the sacrificial metal contained in the sacrificial metal particles included in the first gas diffusion layer to the active metal contained in the active metal particles included in the first catalyst layer may be 0.1:1 to 100:1.

[0031] In the membrane electrode assembly according to the present invention, the active metal contained in the active metal particles includes platinum (Pt), and in the Pt 4f XPS spectrum by X-ray photoelectron spectroscopy (XPS) of the first catalyst layer, the ratio (I2 / I1) of the Pt(II) peak intensity (I2) after 90,000 cycles of the accelerated durability test to the Pt(II) peak intensity (I1) before the accelerated durability test may be 0.5 or more.

[0032] In the membrane electrode assembly according to the present invention, the content of the sacrificial metal particles per unit area of the support for the first gas diffusion layer is 0.1 to 100 mg / cm2 It may be.

[0033] The present invention provides a method for manufacturing a membrane electrode assembly. The method for manufacturing the membrane electrode assembly includes a first step of doping a sacrificial metal precursor on a support for a first gas diffusion layer, a second step of reducing the sacrificial metal precursor doped on the support for the first gas diffusion layer to produce a first gas diffusion layer on which sacrificial metal particles are supported on the support for the first gas diffusion layer, a third step of forming a first catalyst layer on one surface of a polymer electrolyte membrane, a fourth step of forming a second catalyst layer on the other surface of the polymer electrolyte membrane, a fifth step of forming the first gas diffusion layer on the first catalyst layer, and a sixth step of forming a second gas diffusion layer on the second catalyst layer.

[0034] The present invention provides an electrode for a fuel cell, and the electrode for a fuel cell includes the above-described composite.

[0035] The present invention provides a fuel cell, and the fuel cell includes the above-described membrane electrode assembly or the above-described electrode for a fuel cell.

Advantages of the Invention

[0036] The composite according to the present invention includes active metal particles and sacrificial metal particles independently supported on a carbon support, so that the deterioration phenomenon of the active metal can be suppressed, the excellent activity of the catalyst can be maintained, and remarkably improved durability can be achieved.

[0037] In the membrane electrode assembly according to the present invention, since the active metal particles are located on the carbon support and the sacrificial metal particles are located on the gas diffusion layer support, for the same reason as the above-described composite, excellent catalytic activity and remarkably improved durability can be achieved.

[0038] The fuel cell according to the present invention includes the above-described composite and / or membrane electrode assembly, so that high charge / discharge durability, long life, etc. can be achieved.

[0039] The method for manufacturing a composite and the method for manufacturing a membrane electrode assembly according to the present invention can greatly improve the activity and durability of a catalyst in an electrode for a fuel cell in a simple process.

Brief Description of the Drawings

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Mode for Carrying Out the Invention

[0041] The embodiments described in this specification may be modified into various other forms, and the technology according to one embodiment is not limited to the embodiments described below. Also, the embodiments of one embodiment are provided to more fully explain the present disclosure to those having average knowledge in the relevant technical field. Here, unless otherwise defined in the technical terms and scientific terms used, they have the meanings commonly understood by those having ordinary knowledge in the technical field to which the present invention pertains, and in the following description and the accompanying drawings, descriptions of known functions and configurations that may obscure the gist of the present invention are omitted.

[0042] The embodiments described in this specification can be modified into various other forms, and the technology according to one embodiment is not limited to the embodiments described below. Also, the embodiments of one embodiment are provided to more fully explain the present disclosure to those having average knowledge in the relevant technical field.

[0043] Also, in this specification and the appended claims, the singular forms are intended to include the plural forms as well, unless otherwise specifically indicated in the context.

[0044] Also, terms such as "comprising" or "having" in this specification and the appended claims mean that the features or components described in the specification exist, and do not preclude in advance the possibility of adding one or more other features or components, unless otherwise specifically limited.

[0045] Also, the numerical ranges used in this specification include the lower limit value and the upper limit value, all values within that range, increments logically derived from the form and width of the defined range, all of the limited values among these, and all possible combinations of the upper and lower limits of different numerically defined ranges.

[0046] Also, unless otherwise specifically defined in the specification of the present invention, values outside the numerical range that may occur due to experimental error or rounding of values are also included in the defined numerical range.

[0047] Also, terms such as "about" and "substantially" as used in this specification and the appended claims are used in a sense that is close to or at that numerical value when manufacturing and material tolerances inherent to the recited meaning are presented, and are used to prevent unscrupulous infringers from improperly using disclosure where exact or absolute numerical values are recited to facilitate understanding of this specification and the appended claims.

[0048] Also, throughout the specification, stating that a component "comprises" another component means that it can further include other components rather than excluding other components, unless there is a specific statement to the contrary.

[0049] Also, in this specification, when a part such as a layer, film, region, plate, etc. is said to be "on" or "above" another part, this includes not only the case where it is "immediately above" the other part, but also the case where there are further other parts in between.

[0050] Also, terms such as first, second, etc. used in this specification can be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

[0051] Hereinafter, the composite of the present invention, the method for manufacturing the composite, the membrane electrode assembly, the method for manufacturing the membrane electrode assembly, the electrode, and different fuel cells from each other will be described in detail.

[0052] The present invention provides a composite, the composite including a carbon support, active metal particles, and sacrificial metal particles that oxidize or reduce in place of the active metal particles, wherein the active metal particles and the sacrificial metal particles are independently supported on the carbon support.

[0053] According to one embodiment, the fact that the above-described active metal particles and sacrificial metal particles are independently supported on the carbon support can mean that the active metal particles and the sacrificial metal particles are physically separated and located.

[0054] By including active metal particles and sacrificial metal particles independently supported on a carbon support, the composite can effectively suppress the deterioration phenomenon of the active metal, maintain the excellent catalytic activity of the noble metal-based catalyst, and have significantly improved durability compared to conventional noble metal-based catalysts.

[0055] Specifically, the composite according to the present invention can effectively suppress the oxidation of the active metal by including sacrificial metal particles that oxidize prior to the active metal particles, and solve the problem of deterioration of the active metal particles that causes a decrease in catalytic activity and durability. Moreover, since the sacrificial metal particles and the active metal particles exist independently, there is an advantage that the sacrificial metal particles do not cover the catalytic active sites of the active metal contained in the active metal particles, and the excellent catalytic activity of the pure active metal catalyst is maintained.

[0056] According to one embodiment, the active metal particles and the sacrificial metal particles may not form an alloy with each other. The fact that the active metal particles and the sacrificial metal particles are independently supported means that even when the active metal particles and the sacrificial metal particles are physically in contact with each other, the active metal contained in the active metal particles and the sacrificial metal contained in the sacrificial metal particles do not form an alloy and do not chemically bond. When the active metal particles and the sacrificial metal particles form an alloy with each other, the sacrificial metal particles may cover the catalytic active sites of the active metal particles, resulting in a decrease in catalytic activity. On the other hand, when the active metal particles and the sacrificial metal particles do not form an alloy with each other and exist independently, the sacrificial metal particles do not cover the catalytic active sites of the active metal contained in the active metal particles, and can have excellent catalytic activity.

[0057] According to one embodiment, the metal contained in the sacrificial metal particles, that is, the sacrificial metal, may have a lower standard reduction potential than the metal contained in the active metal particles, that is, the active metal. The active metal contained in the active metal particles may be a metal having catalytic activity and a higher standard reduction potential than the sacrificial metal contained in the sacrificial metal particles.

[0058] According to one embodiment, the standard reduction potential of the active metal contained in the active metal particles may be 0.7 V or more, 0.8 V or more, 0.9 V or more, or 1.0 V or more, and the upper limit may be 3.0 V or less, 2.5 V or less, 2.0 V or less, or 1.5 V or less. Specifically, the standard reduction potential of the active metal contained in the active metal particles may be 0.7 to 3.0 V, 0.8 to 2.5 V, 0.9 to 2.0 V, or 1.0 to 1.5 V.

[0059] According to one embodiment, the standard reduction potential of the sacrificial metal contained in the sacrificial metal particles can be 0.3 V or more, 0.4 V or more, 0.5 V or more, or 0.6 V or more, and the upper limit may be 1.1 V or less, 1.0 V or less, 0.9 V or less, or 0.8 V or less. Specifically, the standard reduction potential of the sacrificial metal contained in the sacrificial metal particles may be 0.3 to 1.1 V, 0.4 to 1.0 V, 0.5 to 0.9 V, or 0.6 to 0.8 V. The sacrificial metal contained in the sacrificial metal particles can have a standard reduction potential within the above range and a value less than the standard reduction potential of the active metal contained in the active metal particles.

[0060] According to one embodiment, the active metal particles may include one or more metals selected from the group consisting of palladium (Pd), platinum (Pt), gold (Au), ruthenium (Ru), rhodium (Rh), iridium (Ir), osmium (Os), and alloys containing these. The metal contained in the active metal particles is appropriately selected from the above metals and can have the above effects. However, the active metal contained in the active metal particles included in the composite of the present invention is not limited to the above metals, and the active metal contained in the active metal particles and the sacrificial metal contained in the sacrificial metal particles may be appropriately selected as long as they can have the above effects.

[0061] Also, according to one embodiment, the sacrificial metal particles may include one or more metals selected from the group including silver (Ag), palladium (Pd), iridium (Ir), ruthenium (Ru), rhodium (Rh), platinum (Pt), osmium (Os), iron (Fe), aluminum (Al), and alloys containing these. As a non-limiting example of the alloy contained in the sacrificial metal particles, the alloy contained in the sacrificial metal particles may be silver zinc (AgZn), silver tin (AgSn), silver antimony (AgSb), silver indium (AgIn), iron chromium (FeCr), iron molybdenum (FeMo), iron manganese (FeMn), iron tungsten (FeW), iron nickel (FeNi) or iron nickel chromium (FeCrNi), etc., but the present invention is not limited thereto.

[0062] The metal contained in the sacrificial metal particles is appropriately selected from the above-mentioned metals and can have the above-mentioned effects. However, the sacrificial metal contained in the sacrificial metal particles included in the composite of the present invention is not limited to the above-mentioned metals, and the sacrificial metal contained in the sacrificial metal particles and the active metal contained in the active metal particles are each appropriately selected as long as they can have the above-mentioned effects.

[0063] As a non-limiting and advantageous example, the active metal may include platinum (Pt), and since the sacrificial metal includes silver (Ag), the silver can suppress the oxidation of the platinum.

[0064] According to one embodiment, the active metal may include platinum (Pt), and the 2θ value of the maximum peak appearing in the range of 2θ = 39.8 ± 1.0° in the X-ray diffraction (XRD) spectrum of the composite and the 2θ value of the maximum peak appearing in the range of 2θ = 39.8 ± 1.0° in the X-ray diffraction (XRD) spectrum of pure platinum (Pt) The difference can be 0.3° or less. The difference in the 2θ values can be 0.3° or less or 0.2° or less, and more specifically can be 0.1° or less, and the lower limit can be 0°, 0.01° or 0.05°. Specifically, the difference in the 2θ values can be 0.05 - 0.3°, 0.01 - 0.3° or 0 - 0.1°. The composite satisfying the above-mentioned difference in 2θ values has the merit of excellent catalytic activity because platinum (Pt) particles, which are active metal particles, and sacrificial metal particles do not form an alloy with each other. As a non-limiting and advantageous example, the composite can have a maximum peak in the range of 2θ = 39.8 ± 0.2° in the X-ray diffraction (XRD) spectrum.

[0065] According to one embodiment, the active metal may include platinum (Pt), and the composite is Pt 4f by X-ray photoelectron spectroscopy (XPS) 7 / 2 In the XPS spectrum, the ratio (I0 / I II ) of the Pt(0) peak intensity (I0) to the Pt(II) peak intensity (III) can be 1.8 or more, preferably 2.0 or more, more preferably 2.2 or more, and the upper limit can be 3.5 or 3.0. The composite satisfying the ratio of the peaks in the above range can more effectively suppress the deterioration phenomenon of platinum because the ratio of the metallic platinum component among the platinum contained in the composite is high, and can have more excellent catalytic activity and durability.

[0066] According to one embodiment, the active metal may include platinum (Pt), and the composite may have a peak in the range of 11567.2 ± 0.2 eV in the XANES (X-ray absorption near-edge structure) spectrum. The composite having a peak in the above range can more effectively suppress the deterioration phenomenon of platinum because the ratio of the metallic platinum component in the platinum contained therein is high, and can have better catalytic activity and durability.

[0067] According to one embodiment, the atomic ratio of the sacrificial metal to the active metal contained in the composite may be 1:0.1 to 1:50, specifically, it may be 1:0.5 to 1:15, more specifically 1:1 to 1:10, and even more specifically 1:2 to 1:8 or 1:3 to 1:8. The composite can maintain excellent catalytic activity and have significantly improved durability when the ratio of the sacrificial metal and the active metal is selected within the above range. When the composite contains the sacrificial metal in an excessive amount above the above range, the activity of the catalyst may decrease. Also, when the composite contains the sacrificial metal below the above range, the effect of the sacrificial metal oxidizing or reducing in place of the active metal may decrease, and the durability of the composite may be low. As an advantageous example, the total number of atoms of the sacrificial metal is larger than the total number of atoms of the active metal within the above range, and the sacrificial metal can oxidize or reduce in place of the active metal, thereby enhancing the durability of the composite.

[0068] According to one embodiment, the active metal particles and the sacrificial metal particles may have any one or more shapes selected from the group consisting of spherical, angular, linear, and amorphous, but the present invention is not particularly limited by the shapes of the active metal particles and the sacrificial metal particles.

[0069] According to one embodiment, the average particle size of the active metal particles and / or the sacrificial metal particles may be from 0.1 nm to 20 nm, specifically from 1 nm to 10 nm. More specifically, it may be from 1 nm to 5 nm. However, the composite according to the present invention is not necessarily limited by the average particle size of the above-described active metal particles and / or the above-described sacrificial metal particles.

[0070] According to one embodiment, the ratio (D2 / D1) of the average particle size (D2) of the active metal particles after the accelerated durability test (ADT) of the composite to the average particle size (D1) of the active metal particles before the accelerated durability test may be 3 or less. Specifically, the ratio of D2 / D1 may be 0.5 or more, 1 or more, or 1.5 or more, and the upper limit may be 4 or less, 3 or less, or 2.5 or less. Specifically, the ratio of D2 / D1 may be 0.5 to 4, 1 to 3, or 1.5 to 2.5. A composite satisfying the above-described ratio of average particle sizes may mean that the deterioration phenomenon of the active metal is more suppressed by the sacrificial metal, and may mean a composite having significantly improved catalytic activity and durability.

[0071] The conditions for performing the accelerated durability test (ADT) may be applied as proposed by the U.S. Department of Energy (DOE). Specifically, the accelerated durability test may be performed at 80°C and atmospheric pressure while supplying pure hydrogen with a relative humidity of 100% to the anode at a flow rate of 100 sccm and pure nitrogen with a relative humidity of 100% to the cathode at a flow rate of 50 sccm. One cycle of ADT may be composed of a 3-second holding period at 0.6 V, a 0.5-second rising period, and a 3-second holding period at 0.95 V.

[0072] According to one embodiment, the carbon support included in the composite can be used without limitation as long as it is a carbon support containing carbon with excellent chemical stability and electrical conductivity well-known in the art. As a non-limiting example, the carbon support can be one or more selected from Vulcan carbon, carbon paper, carbon filter, carbon fiber, acetylene black, carbon black, Ketjen black, carbon nanotube, graphene, Timcal, and carbon doped with other hetero elements, but the present invention is not particularly limited thereto.

[0073] According to one embodiment, the content of the active metal particles supported on the carbon support may be 1 to 40% by weight, specifically 4 to 30% by weight, more specifically 5 to 24% by weight based on the total weight of the composite.

[0074] According to one embodiment, the content of the sacrificial metal particles supported on the carbon support may be 0.5 to 20% by weight, specifically 2 to 15% by weight, more specifically 2.5 to 12% by weight based on the total weight of the composite.

[0075] According to one embodiment, the composite may be a catalyst for an oxygen reduction reaction (ORR). As detailed above, a composite including a carbon support, active metal particles, and sacrificial metal particles, in which the active metal particles and the sacrificial metal particles are independently supported on the carbon support, can be used as a catalyst having excellent activity and significantly excellent stability compared to conventional pure active metal catalysts in the oxygen reduction reaction.

[0076] FIG. 1 is a schematic diagram for explaining the influence of whether or not silver (Ag) particles, which are sacrificial metal particles, are included on the oxygen reduction reaction (ORR) catalytic activity in a more specific embodiment. Referring to FIG. 1, in a pure platinum catalyst (Pt / C), platinum (Pt) particles are oxidized to generate Pt-O during an anodic potential scan, and Pt-O is reduced during a cathodic potential scan to Pt 0It can return, but due to the failure of the reduction of some Pt - O, platinum exists in an ionic state (Pt 2+ 2+), which may cause the elution of platinum and the occurrence of platinum degradation phenomenon. Different from this, the composite according to the present invention (denoted as Ag + Pt / C in FIG. 1) can prevent platinum from being oxidized by the prior oxidation of silver (Ag) particles having a standard reduction potential lower than that of platinum. Eventually, the composite according to the present invention can generate less Pt - O compared to the pure platinum catalyst, greatly reducing the degradation of platinum. Platinum rich in electrons at the cathode potential can polarize oxygen molecules into oxygen atoms, realizing more stable oxygen reduction reaction (ORR) performance.

[0077] The present invention provides an electrode for a fuel cell including the above - mentioned composite. Further, the present invention provides a fuel cell including the electrode for a fuel cell. The fuel cell according to the present invention may include an anode that produces hydrogen ions and electrons by the oxidation of a fuel substance, a cathode where the reduction of oxygen occurs by the reaction with hydrogen ions and electrons, and an electrolyte layer (membrane) that can efficiently transfer hydrogen ions from the anode to the cathode. By including the composite according to the present invention in the cathode, there is an advantage that not only the efficiency but also the stability of the fuel cell can be improved.

[0078] According to one embodiment, the fuel cell may be a Proton Exchange Membrane Fuel Cell (PEMFC), a Direct Methanol Fuel Cell (DMFC) that uses alcohol as fuel, a Direct Ethanol Fuel Cell (DEFC), an Alkaline Fuel Cell (AFC), a Phosphoric Acid Fuel Cell (PAFC), a Molten Carbonate Fuel Cell (MCFC), a Solid Oxide Fuel Cell (SOFC), etc., but the present invention is not particularly limited by the type of fuel cell.

[0079] According to one embodiment, the fuel cell may be a Proton Exchange Membrane Fuel Cell (PEMFC) that operates at a low temperature and is applicable to transportation means. The proton exchange membrane fuel cell may include a first gas diffusion layer, an anode, a polymer electrolyte membrane, a cathode, and a second gas diffusion layer. Here, hydrogen (H2), which is a fuel substance, is supplied to the anode through the first gas diffusion layer. The supplied hydrogen is oxidized at the anode to generate hydrogen ions, and the generated hydrogen ions can be transmitted to the cathode through the polymer electrolyte membrane. On the cathode, as detailed above, the hydrogen ions react with the oxygen supplied to the cathode through the second gas diffusion layer to generate water. Here, due to the composite according to the present invention included in the cathode, it can have excellent catalytic activity for the oxygen reduction reaction (ORR) and significantly excellent durability, and the stability of the fuel cell can be improved.

[0080] According to one embodiment, the first gas diffusion layer and the second gas diffusion layer may include substances well-known in the art that can smoothly supply the supplied fuel substances, air, and / or oxygen and have electrical conductivity, but the present invention is not limited thereto.

[0081] According to one embodiment, in the fuel cell, the reduction rate of the energy density after 30,000 cycles of an accelerated durability test (ADT) may be 40% or less, 30% or less, 25% or less, or 20% or less, and the lower limit may be 1% or more, 5% or more, 10% or more, or 15% or more. Specifically, the reduction rate of the energy density of the fuel cell after performing 30,000 cycles of the accelerated durability test may be 1 to 40%, 5 to 30%, 10 to 25%, or 15 to 20%. By including the above-described composite, the fuel cell can maintain a high energy density even after an accelerated durability test of 30,000 cycles or more.

[0082] According to one embodiment, the conditions for performing the 30,000-cycle accelerated durability test (ADT) may be applied as proposed by the United States Department of Energy (DOE). Specifically, the accelerated durability test may be performed at 80°C and ambient pressure while supplying pure hydrogen with a relative humidity of 100% to the anode at a flow rate of 100 sccm and pure nitrogen with a relative humidity of 100% to the cathode at a flow rate of 50 sccm. One cycle of the accelerated durability test may be composed of a 3-second holding period at 0.6 V, a 0.5-second rising period, and a 3-second holding period at 1.0 V.

[0083] The present invention provides a method for manufacturing a composite. The method for manufacturing the composite includes mixing a dispersion liquid containing a carbon support carrying active metal particles and a solution containing a sacrificial metal precursor to produce a first reaction solution, and adding a reducing agent to the first reaction solution to synthesize a composite in which the active metal particles and the sacrificial metal particles are independently supported on the carbon support.

[0084] The present invention provides still another manufacturing method of a composite. The still another manufacturing method of the composite includes a step of mixing a dispersion liquid containing a carbon support carrying active metal particles and a dispersion liquid containing a carbon support carrying sacrificial metal particles to produce a second reaction solution, and a step of adding a reducing agent to the second reaction solution to synthesize a composite in which the active metal particles and the sacrificial metal particles are independently carried on the carbon support.

[0085] When describing each of the manufacturing methods of the composite according to the present invention, since the carbon support, the active metal particles, the sacrificial metal particles, etc. are the same as or similar to the contents detailed in the composite above, the manufacturing method of the composite according to the present invention includes all the contents detailed in the composite above.

[0086] Hereinafter, the manufacturing method of the composite according to the present invention will be described in detail. Also, the manufacturing method of the composite and still another manufacturing method of the composite are collectively referred to as the manufacturing method of the composite.

[0087] FIG. 2 and FIG. 3 are schematic diagrams of a manufacturing method of a composite according to an embodiment of the present invention. Referring to FIG. 2 and FIG. 3, the manufacturing method of the composite according to the present invention will be described, but this is for facilitating the understanding of the present invention and the present invention is not limited by the drawings.

[0088] Referring to FIG. 2, according to an embodiment, the manufacturing method of the composite can manufacture a composite in which active metal particles and sacrificial metal particles are independently carried on a carbon support in a simple manner. The composite manufactured by the above-described manufacturing method of the composite can effectively suppress the deterioration phenomenon of the active metal, maintain the excellent catalytic activity of the noble metal-based catalyst, and have significantly improved durability compared with the conventional noble metal-based catalyst.

[0089] According to an embodiment, in the step of manufacturing the first reaction solution, 0.5 to 20 parts by weight, specifically 2 to 15 parts by weight, specifically 2.5 to 12 parts by weight of a sacrificial metal precursor may be used with respect to 100 parts by weight of the carbon support carrying the active metal particles.

[0090] According to one embodiment, the dispersion solvents contained in the dispersion liquid for the step of manufacturing the first reaction solution and the solution containing the sacrificial metal precursor may each use one or more solvents selected from the group consisting of water, isopropanol, toluene, ethanol, n-propanol, n-butylacetate, ethylene glycol, butyl carbitol, and butyl carbitol acetate. However, the present invention is not limited to the above solvents, and appropriate solvents may be selected according to the chemical species contained in the carbon support carrying the active metal particles and the sacrificial metal precursor.

[0091] According to one embodiment, the sacrificial metal precursor may be a chloride, iodide, sulfide, fluoride, hydroxide, carbonate, and / or nitrate containing a metal having a standard reduction potential lower than that of the active metal contained in the active metal particles. As a non-limiting example, since the sacrificial metal may be silver (Ag), the sacrificial metal precursor may be silver nitrate (AgNO3).

[0092] According to one embodiment, the reducing agent for the step of synthesizing the composite may be one or more reducing agents selected from the group consisting of sodium hydride (NaH), sodium borohydride (NaBH4), lithium aluminum hydride (LiAlH4), hydrazine (N2H4), diisobutylaluminum hydride (DIBAH), and potassium triethylborohydride (KEt3BH).

[0093] Referring to FIG. 3, in still another manufacturing method of the composite according to an embodiment, in the step of manufacturing the second reaction solution, the carbon support carrying the active metal particles and the carbon support carrying the sacrificial metal particles may have all or part of the active metal and / or the sacrificial metal in a state where the reduction reaction is not completed.

[0094] In the step of synthesizing the composite included in still another manufacturing method of the composite according to an embodiment, the reduction reaction performed using the reducing agent may be carried out at 25 to 200 °C, but the present invention is not particularly limited thereby.

[0095] Regarding the dispersion solvent and the reducing agent included in still another manufacturing method of the composite according to an embodiment, since they are the same as those included in the above-described manufacturing method of the composite, specific descriptions are omitted.

[0096] According to an embodiment, the composite may further have a third manufacturing method. The third manufacturing method may include a step of mixing a carbon support carrying active metal particles and a carbon support carrying sacrificial metal particles to produce a mixture, and a step of heating the mixture to synthesize a composite in which the active metal particles and the sacrificial metal particles are independently supported on the carbon support.

[0097] According to an embodiment, in the third manufacturing method of the composite, the temperature for heating the mixture may be 100 °C or higher, 150 °C or higher, or 200 °C or higher, and the upper limit may be 600 °C or lower, 500 °C or lower, or 400 °C or lower. Specifically, the temperature for heating the mixture may be 100 to 600 °C, 150 to 500 °C, or 200 to 400 °C.

[0098] According to an embodiment, the step of heating the mixture to synthesize a composite in which the active metal particles and the sacrificial metal particles are independently supported from the carbon support may be carried out in an atmosphere of one or more mixed gases selected from the group including inert gases such as nitrogen, helium, and argon, hydrogen gas, and ammonia.

[0099] The third method for manufacturing the composite can, in the same manner as the above-described method for manufacturing the composite, produce a composite in which active metal particles and sacrificial metal particles are independently supported on a carbon support in a simple manner. The composite produced by the above-described manufacturing method can effectively suppress the deterioration phenomenon of the active metal, maintain the excellent catalytic activity of the noble metal-based catalyst, and can have significantly improved durability compared to conventional noble metal-based catalysts. The active metal may be one or more selected from the group including palladium (Pd), platinum (Pt), gold (Au), ruthenium (Ru), rhodium (Rh), iridium (Ir), osmium (Os), and alloys containing these. The sacrificial metal can be selected from metals having a standard reduction electrode potential lower than that of the selected active metal.

[0100] The present invention provides a membrane electrode assembly, which includes a cathode including a first catalyst layer and a first gas diffusion layer, an anode including a second catalyst layer and a second gas diffusion layer, and a polymer electrolyte membrane disposed between the cathode and the anode. The first catalyst layer contains active metal particles, and the first gas diffusion layer includes a support for the first gas diffusion layer and sacrificial metal particles supported on the support for the first gas diffusion layer and oxidizing or reducing instead of the active metal particles.

[0101] When describing the membrane electrode assembly according to the present invention, since the active metal particles, sacrificial metal particles, etc. are the same as or similar to the content detailed in the above composite, the membrane electrode assembly according to the present invention includes all the content detailed in the above composite.

[0102] Hereinafter, the membrane electrode assembly of the present invention will be described in more detail.

[0103] In the membrane electrode assembly according to one embodiment, since the gas diffusion layer for the cathode, i.e., the first gas diffusion layer, contains the sacrificial metal particles, the deterioration phenomenon of the active metal contained in the catalyst layer for the cathode, i.e., the first catalyst layer, can be effectively suppressed, and it can have significantly improved durability compared to a conventional membrane electrode assembly that does not contain sacrificial metal particles.

[0104] FIG. 30 is a diagram illustrating a schematic view of a membrane electrode assembly according to one embodiment of the present invention. Specifically, the membrane electrode assembly according to one embodiment may have a structure in which a first gas diffusion layer 10, a first catalyst layer 20, a polymer electrolyte membrane 30, a second catalyst layer (or a catalyst layer for the anode, not shown), and a second gas diffusion layer (or a gas diffusion layer for the anode, not shown) are laminated in this order.

[0105] FIG. 31 is a diagram illustrating the operating principle of a fuel cell by containing sacrificial metal particles. Specifically, FIG. 31(a) is a diagram illustrating a case where a gas diffusion layer that does not contain sacrificial metal particles 2 is used, and a deterioration phenomenon of the active metal particles occurs as the fuel cell operates. On the other hand, FIG. 31(b) is a diagram illustrating a case where the gas diffusion layer 10 containing the sacrificial metal particles 2 is used. As the fuel cell operates, the sacrificial metal particles 2 are oxidized prior to the active metal particles, and the oxidation of the active metal particles can be effectively suppressed, and the deterioration problem of the active metal particles can be solved. Thereby, the life of the catalytic activity can be significantly extended, and the performance of the fuel cell to which this is applied can be maintained in the long term. Further, different from the conventional technique of coating the surface of the active metal particles to cover the catalytic active sites of the active metal in order to suppress the deterioration phenomenon, the present invention solves the deterioration problem of the active metal by containing the sacrificial metal particles 2 on the support 1 for the first gas diffusion layer, so there is an advantage that the sacrificial metal particles 2 do not cover the catalytic active sites of the active metal and the excellent catalytic activity of the active metal catalyst is maintained. That is, the membrane electrode assembly of the present invention is excellent in catalytic activity and can have significantly improved durability.

[0106] According to one embodiment, one surface of the support for the first gas diffusion layer where the sacrificial metal particles are located may face one surface of the first catalyst layer. Specifically, the sacrificial metal particles included in the support for the first gas diffusion layer may be located in direct contact with one surface of the first catalyst layer. Therefore, the sacrificial metal particles included in the support for the first gas diffusion layer can more effectively suppress the oxidation of the active metal particles included in the first catalyst layer.

[0107] According to one embodiment, the second catalyst layer and the second gas diffusion layer included in the anode may include substances widely known in the art for forming an anode. As an example, the anode may include a second catalyst layer including the active metal particles and a second gas diffusion layer including a support for the second gas diffusion layer. That is, the support for the second gas diffusion layer may not include sacrificial metal particles.

[0108] According to one embodiment, the second catalyst layer includes active metal particles, and the second gas diffusion layer may include a support for the second gas diffusion layer and sacrificial metal particles supported on the support for the second gas diffusion layer that oxidize or reduce instead of the active metal particles. Specifically, the second catalyst layer includes active metal particles, and the second gas diffusion layer may include a support for the second gas diffusion layer and sacrificial metal particles including a sacrificial metal that oxidizes or reduces instead of the active metal, supported on the support for the second gas diffusion layer. Further, when the second gas diffusion layer includes the sacrificial metal particles, one surface of the support for the second gas diffusion layer where the sacrificial metal particles are located may face one surface of the second catalyst layer.

[0109] According to one embodiment, the active metal particles included in the second catalyst layer and the active metal particles included in the first catalyst layer may have different compositions from each other. Also, the sacrificial metal particles supported on the support for the first gas diffusion layer and the sacrificial metal particles supported on the support for the second gas diffusion layer may also have different compositions from each other. As a non-limiting example, according to one embodiment of the present invention, the active metal particles included in the first catalyst layer may include palladium (Pd), the active metal particles included in the second catalyst layer may include platinum (Pt), the sacrificial metal particles included in the first gas diffusion layer may include silver (Ag), and the sacrificial metal particles included in the second gas diffusion layer may include aluminum (Al).

[0110] According to one embodiment, the metal included in the sacrificial metal particles, that is, the sacrificial metal, can have a standard reduction potential lower than that of the metal included in the active metal particles, that is, the active metal. The active metal included in the active metal particles may be a metal having catalytic activity and a standard reduction potential higher than that of the sacrificial metal included in the sacrificial metal particles.

[0111] According to one embodiment, the standard reduction potential of the active metal included in the active metal particles may be 0.7 V or more, 0.8 V or more, 0.9 V or more, or 1.0 V or more, and the upper limit may be 3.0 V or less, 2.5 V or less, 2.0 V or less, or 1.5 V or less. Specifically, the standard reduction potential of the active metal included in the active metal particles may be 0.7 to 3.0 V, 0.8 to 2.5 V, 0.9 to 2.0 V, or 1.0 to 1.5 V.

[0112] According to one embodiment, the standard reduction potential of the sacrificial metal contained in the sacrificial metal particles may be 0.3 V or more, 0.4 V or more, 0.5 V or more, or 0.6 V or more, and the upper limit may be 1.1 V or less, 1.0 V or less, 0.9 V or less, or 0.8 V or less. Specifically, the standard reduction potential of the sacrificial metal contained in the sacrificial metal particles may be 0.3 to 1.1 V, 0.4 to 1.0 V, 0.5 to 0.9 V, or 0.6 to 0.8 V. The sacrificial metal contained in the sacrificial metal particles may have a standard reduction potential within the above range and a value less than the standard reduction potential of the active metal contained in the active metal particles.

[0113] According to one embodiment, the active metal particles may include one or more metals selected from the group consisting of palladium (Pd), platinum (Pt), gold (Au), ruthenium (Ru), rhodium (Rh), iridium (Ir), osmium (Os), and alloys containing these. The metal contained in the active metal particles is appropriately selected from the above-mentioned metals and may have the above-mentioned effects. However, the active metal contained in the active metal particles included in the membrane electrode assembly of the present invention is not limited to the above-mentioned metals, and the active metal contained in the active metal particles and the sacrificial metal contained in the sacrificial metal particles are each appropriately selected as long as they can have the above-mentioned effects.

[0114] Also, according to one embodiment, the sacrificial metal particles may include one or more metals selected from the group consisting of silver (Ag), palladium (Pd), iridium (Ir), ruthenium (Ru), rhodium (Rh), platinum (Pt), osmium (Os), iron (Fe), aluminum (Al), and alloys containing these. As a non-limiting example of the alloy contained in the sacrificial metal particles, the alloy may include silver zinc (AgZn), silver tin (AgSn), silver antimony (AgSb), silver indium (AgIn), iron chromium (FeCr), iron molybdenum (FeMo), iron manganese (FeMn), iron tungsten (FeW), iron nickel (FeNi), or iron nickel chromium (FeCrNi), etc., but the present invention is not limited thereto.

[0115] The metal contained in the sacrificial metal particles is appropriately selected from the above-mentioned metals and can have the above-mentioned effects. However, the sacrificial metal contained in the sacrificial metal particles included in the membrane electrode assembly of the present invention is not limited to the above-mentioned metals, and the sacrificial metal contained in the sacrificial metal particles and the active metal contained in the active metal particles can be appropriately selected as long as they can have the above-mentioned effects.

[0116] As a non-limiting and advantageous example, the active metal may include platinum (Pt), and the sacrificial metal includes silver (Ag), so that the silver can suppress the oxidation of the platinum.

[0117] According to one embodiment, the sacrificial metal particles and / or the active metal particles may have any one or more shapes selected from the group consisting of spherical, angular, linear, and amorphous, but the present invention is not particularly limited by the shapes of the sacrificial metal particles and / or the active metal particles.

[0118] According to one embodiment, the average particle diameter of the active metal particles and / or the sacrificial metal particles may be 0.1 nm to 20 nm, specifically 1 nm to 10 nm. More specifically, it may be 1 nm to 5 nm, but the composite according to the present invention is not necessarily limited by the average particle diameter of the above-mentioned active metal particles and / or the above-mentioned sacrificial metal particles.

[0119] According to one embodiment, in the Pt 4f XPS spectrum by X-ray photoelectron spectroscopy (XPS) of the first catalyst layer, the ratio (I2 / I1) of the Pt(II) peak intensity (I2) after 90,000 cycles of accelerated durability test (ADT) to the Pt(II) peak intensity (I1) before the accelerated durability test may be 0.5 or more, specifically 0.6 or more, more specifically 0.7 or more, and an example of the upper limit may be 1.0. Here, the ratio of the above-mentioned peak intensities is Pt 4f 7 / 2It may be measured by XPS spectrum. Since the change in the peak intensity due to the electrochemical reaction of the first catalyst layer included in the membrane electrode assembly is small, the degradation phenomenon of platinum can be suppressed more effectively, and the membrane electrode assembly can have more excellent catalytic activity and durability.

[0120] Here, the execution conditions of the 90,000-cycle accelerated durability test (ADT) may be applied as proposed in the M2FCT (Million Mile Fuel Cell Truck) protocol. Specifically, the accelerated durability test may be performed while supplying pure hydrogen with a relative humidity of 100% to the anode at a flow rate of 100 sccm and pure nitrogen with a relative humidity of 100% to the cathode at a flow rate of 50 sccm at 80 °C and ambient pressure. One cycle of the accelerated durability test may be composed of a maintenance period of 3 seconds at 0.6 V, a rising period of 0.5 seconds, and a maintenance period of 3 seconds at 1.0 V.

[0121] In one embodiment, the ratio (D2 / D1) of the average particle diameter (D2) of the active metal particles after the 30,000-cycle accelerated durability test (Accelerated durability test, ADT) to the average particle diameter (D1) of the active metal particles before the accelerated durability test may be 3 or less, specifically 2.5 or less, more specifically 2 or less, and even more specifically 1.5 or less, and the lower limit thereof may be 1. The membrane electrode assembly satisfying the above ratio of the average particle diameter may mean the effect that appears because the degradation phenomenon of the active metal is further suppressed by the sacrificial metal, and may mean a membrane electrode assembly having significantly improved catalytic activity and durability.

[0122] Here, the implementation conditions of the 30,000 - cycle accelerated durability test (ADT) may be applied as proposed by the United States Department of Energy (DOE). Specifically, the accelerated durability test may be carried out while supplying pure hydrogen with a relative humidity of 100% to the anode at a flow rate of 100 sccm and pure nitrogen with a relative humidity of 100% to the cathode at a flow rate of 50 sccm at 80°C and ambient pressure. One cycle of the accelerated durability test may be composed of a 3 - second holding period at 0.6V, a 0.5 - second rising period, and a 3 - second holding period at 1.0V.

[0123] According to one embodiment, the content of the sacrificial metal particles per unit area of the support for the first gas diffusion layer may be 0.1 - 100 mg / cm 2 and specifically 0.1 - 50 mg / cm 2 and specifically 0.1 - 20 mg / cm 2 and more specifically 0.1 - 10 mg / cm 2 However, the content of the sacrificial metal particles contained in the membrane - electrode assembly according to the present invention is not particularly limited thereto. However, the content of the sacrificial metal particles per unit area of the support for the first gas diffusion layer satisfies the above - mentioned range, can maintain excellent catalytic activity, and can have significantly improved durability. When the support for the first gas diffusion layer contains the sacrificial metal particles less than the above - mentioned range, it may be difficult to suppress the deterioration phenomenon of the active metal. When the support for the first gas diffusion layer contains the sacrificial metal particles more than the above - mentioned range, the catalytic activity decreases, and the performance of the fuel cell including the membrane - electrode assembly may decrease.

[0124] According to one embodiment, the atomic ratio of the sacrificial metal contained in the sacrificial metal particles included in the first gas diffusion layer to the active metal contained in the active metal particles included in the first catalyst layer may be 0.1:1 to 100:1. The atomic ratio of the sacrificial metal contained in the sacrificial metal particles included in the first gas diffusion layer to the active metal contained in the active metal particles included in the first catalyst layer is based on 1 mole of the active metal, and the sacrificial metal can be 0.1 mole or more, 0.5 mole or more, 1 mole or more, 2 moles or more, 3 moles or more, 5 moles or more, or 10 moles or more, and the upper limit may be 100 moles or less, 90 moles or less, 80 moles or less, 70 moles or less, 60 moles or less, 50 moles or less, or 30 moles or less. Specifically, the atomic ratio of the sacrificial metal contained in the sacrificial metal particles included in the first gas diffusion layer to the active metal contained in the active metal particles included in the first catalyst layer is based on 1 mole of the active metal, and the sacrificial metal may be 0.1 to 100 moles, 0.5 to 90 moles, 1 to 80 moles, 3 to 70 moles, 5 to 60 moles, 10 to 50 moles, or 10 to 30 moles. As an advantageous example, the total number of atoms of the sacrificial metal is greater than the total number of atoms of the active metal, and the sacrificial metal can be oxidized or reduced instead of the active metal, thereby enhancing the durability of the membrane electrode assembly.

[0125] According to one embodiment, the ratio of the sacrificial metal to the active metal contained in the membrane electrode assembly can be higher than the ratio of the sacrificial metal to the active metal contained in the composite. Specifically, as described above, the membrane electrode assembly and the composite can have a ratio of active metal:sacrificial metal selected within the above range. However, the membrane electrode assembly can have a non-decreasing catalytic activity even though it contains a higher ratio of the sacrificial metal than the composite under optimal conditions. Therefore, the membrane electrode assembly can have the same catalytic activity and higher durability even though it contains more sacrificial metal than the composite. Also, the membrane electrode assembly can have the same durability and higher catalytic activity even though it contains an amount of sacrificial metal similar to that of the composite.

[0126] According to one embodiment, the support for the first gas diffusion layer and the support for the second gas diffusion layer may contain a carbon-based material. The carbon-based material can be any material widely known in the art that allows the supplied fuel material, air, or oxygen to be smoothly supplied and has electrical conductivity, and can be used without limitation as long as it can be synthesized by those skilled in the art based on ordinary general technical knowledge or purchased commercially. As a non-limiting example, the carbon-based material may be one or more selected from vulcanized carbon, carbon paper, carbon filter, carbon fiber, acetylene black, carbon black, ketjen black, carbon nanotube, graphene, timcal, and carbon doped with other hetero elements, but the membrane electrode assembly according to the present invention is not particularly limited thereto. The support for the first gas diffusion layer and the support for the second gas diffusion layer may be supports made of the same material as each other or supports made of different materials from each other.

[0127] According to one embodiment, when the membrane electrode assembly is applied to a fuel cell, which is any one of energy conversion devices, the first catalyst layer may contain a catalyst for an oxygen reduction reaction (ORR), and the second catalyst layer may contain a catalyst for a hydrogen oxidation reaction (HOR). Specifically, in the first catalyst layer and the second catalyst layer, active metal particles may be supported on the support for the first catalyst layer and the support for the second catalyst layer, respectively.

[0128] According to one embodiment, when the membrane electrode assembly is applied to a water splitting reaction, which is any one of energy conversion devices, the first catalyst layer may contain a catalyst for a hydrogen evolution reaction (HER), and the second catalyst layer may contain a catalyst for an oxygen evolution reaction (OER). Specifically, in the first catalyst layer and the second catalyst layer, active metal particles may be supported on the support for the first catalyst layer and the support for the second catalyst layer, respectively.

[0129] According to one embodiment, the content of the active metal particles supported on the support for the first catalyst layer or the support for the second catalyst layer may be 1 to 80% by weight, specifically 4 to 40% by weight, more specifically 5 to 24% by weight, respectively, based on the total weight of the first catalyst layer or the second catalyst layer. However, the membrane electrode assembly according to the present invention is not particularly limited thereto.

[0130] According to one embodiment, the support for the first catalyst layer and the support for the second catalyst layer may contain a carbon-based substance. The carbon-based substance can be used without limitation as long as it is a substance containing carbon that is well-known in the art for its excellent chemical stability and electrical conductivity. It is not restricted whether synthesized by those skilled in the art based on ordinary general technical knowledge or purchased and used as commercially available products. As a non-limiting example, the carbon-based substance can be one or more selected from vulcan carbon, carbon paper, carbon filter, carbon fiber, acetylene black, carbon black, ketjen black, carbon nanotube, graphene, timcal, and carbon doped with other hetero elements, but is not particularly limited thereto. The support for the first catalyst layer and the support for the second catalyst layer may be supports made of the same substance as each other, or may be supports made of different substances from each other.

[0131] The present invention further provides another fuel cell, and the said another fuel cell includes the membrane electrode assembly described above. The said another fuel cell may be a fuel cell different from the fuel cell including the composite according to the present invention above. However, since the functions and effects of the sacrificial metal particles and the active metal particles are the same or similar, the said another fuel cell including the membrane electrode assembly includes all the contents detailed in the fuel cell including the composite described above. Also, hereinafter, before describing the said another fuel cell, the said another fuel cell is generally referred to as a fuel cell.

[0132] The present invention provides a fuel cell including a membrane electrode assembly as described above. By including the membrane electrode assembly, the fuel cell, i.e., the energy conversion device, has improved performance, particularly significantly improved durability, and can maintain the performance of the energy conversion device in the long term. Specifically, even after an accelerated durability test (ADT) under severe conditions, the retention rates of the electrochemical active surface area (ECSA), maximum power density, current density, and mass activity per unit mass are high, and the increase in charge transfer resistance can be significantly reduced.

[0133] According to one embodiment, the fuel cell may have a retention rate of the maximum power density after 30,000 cycles of accelerated durability test (ADT) of 80% or more, specifically 85% or more, more specifically 90% or more, and even more specifically 95% or more, compared to before the accelerated durability test. Also, the fuel cell may have a retention rate of the maximum power density after 90,000 cycles of accelerated durability test, which is a more severe condition, of 70% or more, specifically 75% or more, and more specifically 80% or more, compared to before the accelerated durability test.

[0134] According to one embodiment, the fuel cell may have a retention rate of the current density at 0.2V after 30,000 cycles of accelerated durability test (ADT) of 80% or more, specifically 85% or more, more specifically 90% or more, and even more specifically 95% or more, compared to before the accelerated durability test. Also, the fuel cell may have a retention rate of the current density at 0.2V after 90,000 cycles of accelerated durability test, which is a more severe condition, of 70% or more, specifically 75% or more, and more specifically 80% or more, compared to before the accelerated durability test.

[0135] According to one embodiment, after 30,000 cycles of accelerated durability test (ADT), the activity retention rate per unit mass at 0.9V of the fuel cell may be 60% or more compared to before the accelerated durability test, specifically 70% or more, more specifically 80% or more, and even more specifically 90% or more or 95% or more. Also, for the fuel cell under more severe conditions, after 90,000 cycles of accelerated durability test, the activity retention rate per unit mass at 0.9V may be 50% or more compared to before the accelerated durability test, specifically 60% or more, and more specifically 75% or more.

[0136] The fuel cell according to the present invention is one of the energy conversion devices, and the energy conversion device may include a fuel cell and a water electrolysis cell, etc. Therefore, the membrane electrode assembly and / or the composite can also be used in the water electrolysis cell and can have similar remarkable effects.

[0137] According to one embodiment, as a non-limiting example of the fuel cell, the fuel cell may be a proton exchange membrane fuel cell (PEMFC) that operates at low temperature and is applicable to transportation means.

[0138] The present invention provides a method for manufacturing a membrane electrode assembly. The method for manufacturing the membrane electrode assembly includes a first step of doping a sacrificial metal precursor on a support for a first gas diffusion layer, a second step of reducing the sacrificial metal precursor doped on the support for the first gas diffusion layer to produce a first gas diffusion layer on which sacrificial metal particles are supported on the support for the first gas diffusion layer, a third step of forming a first catalyst layer on one surface of a polymer electrolyte membrane, a fourth step of forming a second catalyst layer on the other surface of the polymer electrolyte membrane, a fifth step of forming the first gas diffusion layer on the first catalyst layer, and a sixth step of forming a second gas diffusion layer on the second catalyst layer.

[0139] When describing each of the manufacturing methods of the membrane electrode assembly according to the present invention, the support for the gas diffusion layer, the active metal particles, the sacrificial metal particles, etc. are the same as or similar to the content detailed in the above membrane electrode assembly. Thus, the manufacturing method of the membrane electrode assembly according to the present invention includes all the content detailed in the above membrane electrode assembly.

[0140] Hereinafter, the manufacturing method of the membrane electrode assembly of the present invention will be described in more detail.

[0141] FIG. 3 is a schematic diagram showing a process for manufacturing a first gas diffusion layer in which the sacrificial metal particles are supported on the first gas diffusion layer support. Referring to FIG. 3, the manufacturing method of the membrane electrode assembly according to the present invention will be described. This is for facilitating the understanding of the present invention, and the manufacturing method of the membrane electrode assembly according to the present invention is not to be construed as being limited to the drawings.

[0142] According to the manufacturing method of the membrane electrode assembly according to the present invention, the manufacturing method of the membrane electrode assembly can manufacture a highly durable membrane electrode assembly that can effectively suppress the degradation phenomenon of the active metal in a simple manner.

[0143] According to one embodiment, the sacrificial metal precursor in the first step may be a chloride, iodide, sulfide, fluoride, hydroxide, carbonate, and / or nitrate containing a metal having a standard reduction potential lower than that of the active metal contained in the active metal particles. As a non-limiting example, the sacrificial metal precursor may be a nitrate containing a metal having a standard reduction potential lower than that of the active metal contained in the active metal particles, specifically, silver nitrate (AgNO3).

[0144] According to one embodiment, in the first step, a solution containing a sacrificial metal precursor can be doped onto the support for the first gas diffusion layer. The solvent used at this time may be one or more solvents selected from the group including water, isopropanol, toluene, ethanol, n-propanol, n-butylacetate, ethylene glycol, butyl carbitol, and butyl carbitol acetate. However, the present invention is not limited to the above solvents, and an appropriate solvent can be selected according to the species of the sacrificial metal precursor.

[0145] According to one embodiment, in the second step, the support for the first gas diffusion layer doped with the sacrificial metal precursor may be immersed in a solution containing a reducing agent. The solvent used at this time may be the same as the solvent detailed in the first step.

[0146] According to one embodiment, the reducing agent may be one or more reducing agents selected from the group including sodium hydride (NaH), sodium borohydride (NaBH4), lithium aluminum hydride (LiAlH4), hydrazine (N2H4), diisobutylaluminum hydride (DIBALH), and potassium triethylborohydride (KEt3BH).

[0147] According to one embodiment, for the third step and the fourth step, methods widely known in the art for forming layers or thin films can be used. As a non-limiting example, after applying a slurry for forming a catalyst layer containing the active metal particles to each surface of the polymer electrolyte membrane and then drying it, the first catalyst layer and the second catalyst layer may be formed.

[0148] According to one embodiment, the fifth step and the sixth step can use methods widely known in the art for laminating layers or thin films. As a non-limiting example, the first gas diffusion layer and the second gas diffusion layer may be assembled and formed on the first catalyst layer and the second catalyst layer respectively without hot-pressing.

[0149] According to one embodiment, the polymer electrolyte membrane is applicable in the field of fuel cells and can be applied without limitation as long as it is a polymer material known in the art. As a non-limiting example, the polymer electrolyte membrane may be a polymer into which one or more functional groups selected from the group including sulfonated benzimidazole-based, sulfonated polyimide-based, sulfonated polyetherimide-based, sulfonated polyphenylene sulfide-based, sulfonated polysulfone-based, sulfonated polyether-based, sulfonated polyether ketone-based, sulfonated polyether-ether ketone-based, sulfonated polyether sulfone-based, sulfonated polyphenylquinoxaline-based, and sulfonated partial fluorine-based are introduced, but the present invention is not limited thereto.

[0150] Hereinafter, examples and experimental examples will be specifically exemplified and described below. However, the examples and experimental examples described later are only illustrative in part, and the technology described in this specification is not limited thereto.

[0151] (Example 1) Production of Composite 1 100 mg of commercially available Pt / C (19.4 wt% Pt, Tanaka Holdings Co., Ltd) for commercial sale was sonicated in 100 ml of a 50% isopropanol (IPA) solution for more than 30 minutes to produce a dispersion. 0.1 ml of an AgNO3 solution (10 mg Ag+ / ml) was added to the produced dispersion and stirred for 10 minutes to produce a reaction solution. 1 ml of a NaBH4 solution (50 mg / ml) was added to the produced reaction solution and subjected to a reduction reaction for 1 hour. The solution after the reaction was completed was washed with deionized water and then dried in an oven overnight to produce a composite 1 (or, Ag1+Pt / C) in which platinum (Pt) particles and silver (Ag) particles were supported on a carbon support. As a result of analysis by inductively coupled plasma-optical emission spectroscopy (ICP-OES), the atomic ratio of silver to platinum contained in composite 1 was 1:12.7.

[0152] (Example 2) Production of Composite 2 Composite 2 (or, Ag3+Pt / C) was produced in the same manner as in Example 1, except that 0.3 ml of an AgNO3 solution was used in Example 1. As a result of ICP-OES analysis, the atomic ratio of silver to platinum contained in composite 2 was 1:4.41.

[0153] (Example 3) Production of Composite 3 Composite 3 (or, Ag5+Pt / C) was produced in the same manner as in Example 1, except that 0.5 ml of an AgNO3 solution was used in Example 1. As a result of ICP-OES analysis, the atomic ratio of silver to platinum contained in composite 3 was 1:2.21.

[0154] (Example 4) Production of Gas Diffusion Layer with Sacrificial Metal Supported 5 cm 2A commercial gas diffusion carbon layer (Sigracet 39 BC) having an area of was used as a support for the gas diffusion layer. The support for the gas diffusion layer was washed with acetone and dried on a hot plate at 60 °C. An AgNO3 solution of 2 mg Ag+ / ml was prepared using isopropanol (IPA) and deionized water mixed at a volume ratio of 1:1 as a solvent. 2.5 ml of the AgNO3 solution was dropped onto the washed and dried support for the gas diffusion layer, and the support for the gas diffusion layer loaded with silver (Ag) ions was immersed in a 10 mM NaBH4 solution for 10 minutes to reduce the silver (Ag) ions to metallic silver (Ag), and then dried on a hot plate at 60 °C. After being completely dried, the support for the gas diffusion layer treated with NaBH4 was washed using isopropanol (IPA) and deionized water mixed at a volume ratio of 1:1, and dried overnight in an oven at 60 °C to produce a gas diffusion layer with silver (Ag) particles supported on the support.

[0155] According to the analysis results by inductively coupled plasma-optical emission spectroscopy (ICP-OES, iCAP PRO ICP-OES, Thermo Fisher), the silver (Ag) loading amount supported on the support was 1 mg / cm 2 was.

[0156] (Example 5) Fabrication of Membrane Electrode Assembly The membrane electrode assembly (MEA) is a Nafion N211 membrane (5 cm 2The catalyst slurry was spray-coated on both sides of (the area of), dried on a hot plate at 60 °C for several hours, and an anode catalyst layer and a cathode catalyst layer were formed respectively. Then, the gas diffusion layer manufactured in Example 4 was assembled on each catalyst layer without hot-pressing to manufacture a membrane electrode assembly. The catalyst slurry used was composed of commercial Pt / C (19.4 wt% Pt, Tanaka Holdings Co., Ltd), deionized water, IPA, and 5 wt% Nafion solution. The catalyst loading amount was 0.05 mgPt / cm for both the anode and the cathode. 2 It was.

[0157] (Comparative Example 1) Commercial Pt / C An experimental example was conducted using commercial Pt / C (19.4 wt% Pt, Tanaka Holdings Co., Ltd).

[0158] (Comparative Example 2) Preparation of Pt3Ag / C 80 mg of commercial carbon (Ketjen black EC600JD) was sonicated in 50 ml of deionized water for over 1 hour to produce a dispersion. Next, 0.168 ml of H2PtCl6 solution (100 mg Pt4+ / ml) and 0.32 ml of AgNO3 solution (10 mg Ag+ / ml) were added, and the mixture was stirred for 30 minutes to produce a reaction solution. 2 ml of NaBH4 solution (50 mg / ml) was added to the produced reaction solution, and the mixture was stirred for 12 hours. Finally, it was filtered with deionized water to produce Pt3Ag / C in which platinum and silver were supported on the carbon support in an alloy form. As a result of ICP-OES analysis, the atomic ratio of silver and platinum contained in Pt3Ag / C was 1:3.67.

[0159] (Comparative Example 3) Preparation of Ag / C Ag / C was prepared in the same manner as in Example 2, except that commercial carbon (Ketjen black EC600JD) was used instead of commercial Pt / C in Example 2.

[0160] (Comparative Example 4) Preparation of a gas diffusion layer without a sacrificial metal supported thereon 5 cm2 An experimental example was conducted using a commercial gas diffusion carbon layer (Gas diffusion carbon layer, Sigracet 39 BC) having an area as the gas diffusion layer.

[0161] (Comparative Example 5) Manufacture of a membrane electrode assembly without a sacrificial metal supported thereon In Example 5, a membrane electrode assembly was manufactured in the same manner as in Example 5, except that the gas diffusion layer of Comparative Example 4 was used instead of the gas diffusion layer manufactured in Example 4.

[0162] (Experimental Example 1) Chemical property analysis By chemical property analysis, it was confirmed that an alloy of platinum and silver contained in the composite of the example was not formed. Specifically, X-ray diffraction (XRD, Rigaku Smartlab, 40 kV, 15 mA, 4° min -1 , Cu-Kα radiation, λ = 1.55406 A), X-ray photoelectron spectroscopy (XPS, Kratos, AXIS-NOVA, 2.6×10 -9 torr), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM, FEI Themis Z) and energy-dispersive X-ray spectroscopy (EDS, FEI Themis Z) were used. Fig. 4 is a diagram showing the XRD patterns of Comparative Example 1 and Examples 1 to 3. Fig. 5 is a diagram showing the XRD patterns of Comparative Example 1, Comparative Example 2 and Example 2. Referring to these, it can be seen that Comparative Example 1 and Examples 1 to 3 commonly have a main peak at 39.8° corresponding to the (111) face-centered cubic (fcc) Pt (JCPDS no. 04-0802). That is, the composite according to the example has a peak at the same position as Pt / C, which indicates that platinum and silver contained in the composite are not alloyed. In contrast, in the case of Comparative Example 2 having an alloy form, it can be seen that it has a peak at 39.2°, and has shifted by 0.6° compared with Example 2 and Comparative Example 1.

[0163] On the one hand, referring to FIG. 4, it can be seen that the peak intensity on the (111) plane of the example increases compared to the comparative example. This is because the peak on the (111) plane overlaps with a specific peak of Ag (JCPDS number 04 - 0783, fcc Ag) added in the example, and as shown in FIG. 6, it is considered to be due to the increase in the metallic Pt component.

[0164] FIG. 6 is a diagram showing the Pt 4f XPS spectra of Comparative Example 1 and Examples 1 to 3. FIG. 7 is a diagram showing the Ag 3d XPS spectra of Comparative Example 1 and Examples 1 to 3. FIG. 8 is a diagram showing the Pt 4f XPS spectra of Comparative Example 1, Comparative Example 2, and Example 2. FIG. 9 is a diagram showing the Ag 3d XPS spectra of Comparative Example 2, Comparative Example 3, and Example 2.

[0165] Referring to FIG. 6, Comparative Example 1 and Examples 1 to 3 have the same Pt peak positions (Pt 4f 7 / 2 for Pt 0 in the case of ~71.9 eV, Pt 2+ in the case of ~72.9 eV). Referring to FIG. 7, Examples 1 to 3 mainly have a metallic Ag signal (Ag 3d 5 / 2 for Ag 0 in the case of ~368.0 eV), and as the Ag concentration increases, the signal intensity increases without a shift in position. This indicates that the composite according to the example has not formed an alloy. In contrast, referring to FIGS. 8 and 9, Comparative Example 2 shows a slightly higher binding energy in the Pt 4f XPS spectrum than Example 2 and Comparative Example 1, while showing a lower binding energy in the Ag 3d XPS spectrum than Example 2 and Comparative Example 3. That is, the electronic structure of Comparative Example 2 has changed due to the interaction between Pt and Ag.

[0166] On the one hand, referring to FIG. 6, the ratio (I0 / I 7 / 2 ) of the Pt(0) peak intensity (I0) to the Pt(II) peak intensity (I II ) in the Pt 4f II) has values of 1.76 for Comparative Example 1, 1.88 for Example 1, 2.38 for Example 2, and 2.85 for Example 3. That is, as the Ag content contained in the composite increases, the peak intensity of metallic Pt 0 increases, while the peak intensity of Pt 2+ tends to decrease. This is considered to be due to the reduction of Pt 2+ to Pt 0 , which is consistent with the XRD spectrum results in FIG. 4.

[0167] FIG. 10 shows the HAADF-STEM image and the EDS mapping image of Example 2, and FIG. 11 shows the enlarged image thereof. FIG. 12 shows the HAADF-STEM image and the EDS mapping image of Comparative Example 2. Referring to these, in the case of Comparative Example 2, it can be clearly confirmed that an alloy is formed, but in the case of Example 2, both the platinum (Pt) particles and the silver (Ag) particles are uniformly distributed on the carbon support, and it can be seen that they are independently distributed without interaction between the platinum (Pt) particles and the silver (Ag) particles.

[0168] (Experimental Example 2) Analysis of Electrochemical Properties The electrochemical performance for the oxygen reduction reaction was evaluated with a VSP potentiostat (Bio-Logic SAS) having a standard three-electrode cell in 0.1 M HClO4. As the reference electrode, counter electrode, and working electrode, a KCl-saturated Ag / AgCl electrode, a Pt wire, and a rotating disk electrode (RDE, diameter: 3 mm, area: 0.07065 cm 2 ) were used, respectively. Here, 2.5 mg of the powder produced by Comparative Example 1, Comparative Example 2, and Examples 1 to 3 was ultrasonically treated for 30 minutes in a mixed slurry in which 4 ml of deionized water, 1 ml of IPA, and 0.4 ml of a 5 wt% Nafion solution were mixed to produce a uniform slurry, and then the uniform slurry was coated on the RDE to produce a working electrode loaded with Pt in an amount of 50 μg / cm 2 .

[0169] Before the electrochemical performance evaluation, it was stabilized by cyclic voltammetry (CV) with a scan rate of 50 mV / s and a scan range of 0.05 V to 1.15 V for 30 cycles in a nitrogen-saturated 0.1 M HClO4 solution. Linear sweep voltammetry (LSV) was performed at a scan rate of 10 mV / s in an oxygen- or nitrogen-saturated 0.1 M HClO4 solution, and the final polarization curve was obtained by subtracting the current density in nitrogen from the current density in oxygen. CV was performed in an oxygen- or nitrogen-saturated 0.1 M HClO4 solution with a scan rate of 50 mV / s and a scan range of 0.05 V to 1.15 V.

[0170] The accelerated durability test (ADT) was carried out by performing CV with a scan rate of 100 mV / s and a scan range of 0.60 V to 0.95 V in a nitrogen-saturated 0.1 M HClO4 solution for 30,000 (30k) cycles. After the ADT, LSV was performed under the same initial measurement conditions.

[0171] Figure 13 is a diagram showing the results of evaluating the electrochemical performance of Comparative Example 1 and Examples 1 to 3. Specifically, (a) and (b) of Figure 13 are diagrams showing the LSV curve and the CV curve, respectively, and (c) to (f) of Figure 13 are diagrams showing the LSV curves before and after ADT for Comparative Example 1 and Examples 1 to 3, respectively. Figure 14 is a diagram showing the CV curves before and after ADT for Comparative Example 1 and Examples 1 to 3, respectively. Figure 15 is a transmission electron microscope (TEM, FEI Tecnai G2 twin) image before and after ADT for Comparative Example 1 and Example 2, respectively. Figure 16 is a diagram showing the results of evaluating the electrochemical performance of Comparative Example 2 in alloy form. Specifically, (a) of Figure 16 is the LSV curve before and after ADT, (b) of Figure 16 is the CV curve of Comparative Example 1, Comparative Example 2, and Example 2, and (c) of Figure 16 is the CV curve before and after ADT for Comparative Example 2.

[0172] Referring to Fig. 13(a), in the cases of Example 1 and Example 2, the onset and half-wave (E 1 / 2 ) potentials similar to those of Comparative Example 1 are shown, while in the case of Example 3, slightly lower performance is shown. This is presumably because in the case of Example 3, as the silver (Ag) loading amount increases, the aggregated silver nanoparticles block the catalytically active sites of platinum. Referring to Fig. 13(b), in the cases of Examples 1 to 3, a pair of silver (Ag) reduction and oxidation peaks are shown at approximately -0.4 V and approximately -0.55 V, respectively. The maximum value of such redox peaks tends to shift to a lower potential as the silver (Ag) loading amount increases. As the silver (Ag) loading amount increases, the exposed surface area of silver (Ag) becomes higher, thereby providing more redox reaction sites and relatively lowering the overvoltage for the redox reaction. On the other hand, the oxidation of platinum (Pt) shifts to a higher potential as the silver (Ag) loading amount increases. Specifically, it is shown at 0.733 V for Comparative Example 1, 0.745 V for Example 1, 0.781 V for Example 2, and 0.797 V for Example 3. From this, it can be seen that the composite according to the examples can suppress the oxidation of platinum (Pt) by containing silver (Ag) particles.

[0173] Referring to FIGS. 13(c) to 13(f), in the case of Comparative Example 1, the half-wave potential decreased by about 52 mV, while in the case of Example 1 it decreased by 38 mV, and in the case of Example 2 it decreased by about 12 mV. In particular, in the case of Example 3, it can be seen that the initial half-wave potential of 0.790 V was maintained without substantial change during ADT. Also, referring to FIG. 14, during ADT, changes in the electrochemical active surface area (ECSA) due to the dissolution and aggregation of platinum (Pt) caused by the oxidation of platinum (Pt) can be determined. The maintenance rate of ECSA was high as the silver (Ag) loading amount increased. Specifically, it was shown to be 51.6% in the case of Comparative Example 1, 68.4% in the case of Example 1, 84.8% in the case of Example 2, and 100% in the case of Example 3. Also, referring to FIG. 15, in the case of Comparative Example 1, the size of the platinum (Pt) particles increased 2 to 4 times, while in the case of Example 2, it was confirmed that the particle size distribution (2 to 4 nm) was maintained before and after ADT. On the other hand, referring to FIG. 16, in the case of Comparative Example 2 in alloy form, as the silver (Ag) particles covering the catalytic reaction sites of platinum eluted after ADT, the half-wave potential and ECSA increased, but nevertheless, it was found to have significantly lower values and decreased ORR catalytic activity compared to Example 2 and Comparative Example 1.

[0174] That is, it can be seen that the composite according to the example contains sacrificial metal particles capable of suppressing the oxidation of the active metal without forming an alloy with the active metal, and thus has excellent ORR catalytic activity.

[0175] (Experimental Example 3) Characterization of a fuel cell containing a composite For the performance test of a Proton Exchange Membrane Fuel Cell (PEMFC), the Membrane Electrode Assembly (MEA) had an active area of 5 cm 2It was manufactured by a catalyst-coated membrane (CCM). As the anode catalyst, commercial Pt / C (19.4 wt% Pt, Tanaka Holdings Co., Ltd) was used. As the cathode catalyst, the composite manufactured in the examples or comparative examples was used. The CCM was produced by mixing each catalyst with deionized water, IPA, and 5 wt% Nafion solution to form a slurry, and then spray-coating the produced slurry onto a Nafion N211 membrane and drying it on a hot plate at 60 °C for several hours. The catalyst loading amount was 0.05 mg Pt / cm 2 for both the anode and the cathode. Next, the membrane electrode assembly was assembled without hot-pressing with a commercial gas diffusion layer (GDL, SGL 39 BC).

[0176] The proton exchange membrane fuel cell was supplied with pure hydrogen at 100% relative humidity to the anode at a flow rate of 300 sccm, and pure oxygen at 100% relative humidity to the cathode at a flow rate of 1000 sccm, and operated under a back pressure of 80 °C, 0.5 bar and constant current conditions. Electrochemical Impedance Spectroscopy (EIS) was performed at a cell current of 100 mA / cm 2 from 5 kHz to 100 mHz.

[0177] To evaluate the durability of the catalyst, an accelerated durability test (ADT) was performed based on the CV cycle for 30k proposed by the U.S. Department of Energy (DOE). According to the electrocatalyst cycle protocol, at 80 °C and ambient pressure, while supplying pure hydrogen at 100% relative humidity to the anode at a flow rate of 100 sccm and pure nitrogen at 100% relative humidity to the cathode at a flow rate of 50 sccm, it was carried out between 0.6 V and 0.95 V with a hold time of 3 seconds at both potentials. The rise time between both potentials was set to 0.5 seconds.

[0178] Figures 17 and 18 are diagrams showing the performance before and after ADT during 30k cycles of fuel cells to which Comparative Example 1 and Examples 1 to 3 were each applied as the cathode catalyst. Specifically, (a) in FIG. 17 is for Comparative Example 1, (b) in FIG. 17 is for Example 1, (c) in FIG. 17 is for Example 2, and (d) in FIG. 17 is a diagram illustrating the polarization curve and power density curve of the fuel cell to which Example 3 was applied. (a) in FIG. 18 is the maximum power density (P max ) before and after ADT, (b) in FIG. 18 is the current density (j 0.2V ) at 0.2V before and after ADT, and (c) in FIG. 18 is a diagram illustrating the activity per unit mass at 0.9V without iR before and after ADT. FIG. 19 is a diagram illustrating the polarization curve and power density curve of the fuel cell to which Comparative Example 2 in alloy form was applied as the cathode catalyst before and after ADT. FIG. 20 is a diagram illustrating the change in particle size before and after ADT in the fuel cells of Comparative Example 1 and Example 2. Specifically, (a) and (b) in FIG. 20 are TEM images before and after ADT, respectively, of the fuel cell of Comparative Example 1, and (c) and (d) in FIG. 20 are TEM images before and after ADT, respectively, of the fuel cell of Example 2.

[0179] Referring to FIGS. 17 and 18, it can be seen that the fuel cells to which Examples 1 to 3 were applied all have superior durability compared to Comparative Example 1, and as the silver (Ag) loading amount increases, the differences in the maximum power density, current density, and activity per unit mass due to 30k cycles of ADT decrease, and there is a tendency for the durability to increase. On the other hand, referring to FIG. 19, it can be seen that for the fuel cell to which Comparative Example 2 was applied, the maximum power density and current density increase after ADT, but nevertheless, it has significantly lower values compared to Examples 1 to 3 and has a decreased ORR catalytic activity. Referring to FIG. 20, in the case of Example 2, it was confirmed that the average particle size of the platinum (Pt) particles increased from 2.5 nm to 4 nm during ADT, whereas in the case of Comparative Example 1, it increased from 2.5 nm to 10 nm.

[0180] That is, the composite according to the embodiment contains sacrificial metal particles without forming an alloy with the active metal, so that the initial ORR catalytic activity can be maintained or decreased at a low reduction rate even after severe ADT, indicating excellent durability.

[0181] (Experimental Example 4) Elution analysis of metals For the elution analysis of platinum and silver, an in-situ inductively coupled plasma mass spectrometer (ICP-MS, iCAP RQ, Thermo-Fisher Science) was used.

[0182] Specifically, an electrochemical flow cell (EFC) directly fabricated for ICP-MS was coupled. The EFC was composed of a U-shaped channel with an opening diameter of 3 mm for connection to the working electrode (A-002012, Bio-Logic). The graphite tube counter electrode and the Ag / AgCl reference electrode were connected to the inlet and outlet of the EFC, respectively. The working electrode was fabricated by drop-casting the catalyst ink onto glassy carbon (0.07065 cm 2 ) so that 10 μg / cm 2 of the metal was loaded. The catalyst ink for ICP-MS study was prepared by dispersing 5 mg of the catalyst in an aqueous solution containing 1179 μl of deionized water, 50 μl of Nafion, and 186 μl of IPA. The argon-saturated 0.1 M HClO4 electrolyte was mixed with a 5 ppb 187 Re and 0.5 M HNO3-containing internal standard solution and then introduced into the ICP-MS. The elution characteristics of platinum and silver were 187 quantitatively estimated by measuring the 195 Pt and 107 Ag signals relative to Re.

[0183] The electrochemical protocol for online ICP-MS experiments consists of procedures for a chemical dissolution step, an activation step, and a slow scan step. In the chemical dissolution step, no potential is applied. The activation step consists of a CV with a fast scan rate (200 mV / s) of 50 cycles, and the slow scan step consists of a CV with a slow scan rate (5 mV / s) of 5 cycles at 0.05 - 1.2 V RHE The potential was maintained at 0.05 V between the activation step and the slow scan step to stabilize the ICP-MS signal. RHE

[0184] Figures 21 to 23 are diagrams illustrating the results of online ICP-MS experiments conducted for Comparative Example 1 and Example 2. Specifically, Figure 21 is a diagram illustrating the dissolution profiles of platinum and silver under each treatment condition. (a) and (b) of Figure 22 are diagrams illustrating the dissolution rates of platinum and silver with respect to the amount loaded on the working electrode, respectively. Figure 23 is a diagram illustrating the dissolution profile for each cycle performed at a slow scan rate (5 mV / s). Figures 24 to 26 are diagrams illustrating the results of online ICP-MS experiments conducted in the above-described manner for Comparative Example 1 and Comparative Example 2.

[0185] First, after chemically unstable platinum is leached by an acidic electrolyte in the chemical dissolution step, it cannot participate in the reduction reaction, oxidizes, and chemically stable platinum is eluted. Referring to Figures 21 and 22, the dissolution rate of platinum is 0.38% and 0.25% in the chemical dissolution step and the activation step, respectively, for Comparative Example 1, whereas it is 0.19% and 0.12% for Example 2, indicating that the composite of Example 2 has better stability. In the slow scan step, for Comparative Example 1, the dissolution rate of platinum per cycle is 0.10%, whereas for Example 2, it is 0.0043%, which is 23 times less, indicating that hardly any platinum is eluted from the composite of Example 2 and it has significantly improved stability.

[0186] Referring to the drawings inserted in FIG. 21, the activation step will be specifically described. In both Comparative Example 1 and Example 2, the elution behavior of platinum is similar in the range of 300 to 600 seconds, and it can be seen that the silver in Example 2 is also eluted in the same range. However, in the case of Example 2, it can be seen that, unlike Comparative Example 1, almost no platinum and silver are eluted after 600 seconds.

[0187] Referring to FIG. 23, in the case of Comparative Example 1, the average elution rate of platinum is 12 μg / g Pt ·s (3.7×10 16 atom Pt / g Pt ·s) at 0.77V, while in the case of Example 2, it is 0.15 μg / g Pt ·s (4.6×10 14 atom Pt / g Pt ·s), showing a difference of about 80 times. On the other hand, in Example 2, the average elution rate of silver is 1.4 μg / g Ag ·s (7.8×10 16 atom Ag / g Ag ·s).

[0188] Referring to FIGS. 24 to 26, in the case of Comparative Example 2, in the chemical elution step and the activation step, the elution rates of platinum are 0.03% and 0.18% respectively, and the elution rates of silver are 12.26% and 64.43% respectively. The average elution rate of platinum in each cycle of the slow rate step is 4.2 μg / g Pt ·s at 0.77V, and the average elution rate of silver is 66.8 μg / g Ag ·s at 1.08V. That is, in the case of Comparative Example 2 in alloy form, although the elution of platinum is suppressed compared to Comparative Example 1, it cannot effectively suppress the elution of platinum compared to Example 2. As a result, under repeated electrochemical oxidation and reduction potentials, the alloy form is not stable, and silver (Ag) contained in the alloy-form composite cannot perform the sacrificial metal function properly compared to silver (Ag) contained in the composite according to one embodiment.

[0189] That is, it is presumed that the composite according to one embodiment changes to a structure with high resistance to the electrochemical oxidation reaction after an excessive amount (40% with respect to the initial loading amount) of silver is eluted in the chemical elution and activation steps.

[0190] (Experimental Example 5) Analysis of Chemical Structure and Electronic Structure of Composite The analysis of the chemical structure and electronic structure was performed by X-ray absorption spectroscopy (XAS) including XANES (X-ray absorption near edge structure) and EXAFS (extended X-ray absorption fine structure) measurements.

[0191] The XAS spectra were measured at a ring current of 250 mA and 3.0 GeV at the BL8C beam line of the Pohang Light Source (PLS-II). They were collected in both transmission mode and fluorescence mode, and the obtained spectra were processed using the Demeter package.

[0192] A Si(111) double crystal monochromator was used to monochromate the X-ray beam. The higher order harmonic contamination generated during the XAS experiment was adjusted to reduce the intensity of the projected X-ray by 30%.

[0193] In-situ XAS was performed in an electrochemical cell of a standard three-electrode system. As the reference electrode, counter electrode, and working electrode, an Ag / AgCl electrode, a graphite rod, and a carbon paper coated with the catalyst of the example or comparative example were used, respectively. Nitrogen-saturated 0.1 M HClO4 was used as the electrolyte. For the stabilization of the catalyst, 20 CV cycles were performed in the range of 0.05 V to 1.05 V before the XAS measurement. Next, after 30 minutes of stabilization, XAS was analyzed at various potentials from the open circuit voltage (OCV) to 1.5 V by chronoamperometry. The XAS spectra were collected in fluorescence mode by a silicon drift detector (SDD). The obtained spectra were processed using the Demeter package. The Pt oxidation state was evaluated in the white line peak region of the normalized Pt L3-edge XANES spectra.

[0194] Figure 27 is a diagram showing the Ex-situ XAS spectra of the Pt L3-edge (or Ag K-edge) for Comparative Example 1 (or Comparative Example 3), Comparative Example 2, Example 2, Pt foil (or Ag foil), and PtO2 (or AgO2). Specifically, (a) and (b) of Figure 27 are Pt L3-edge XANES spectra, (c) of Figure 27 is a Pt L3-edge FT-EXAFS spectrum, (d) and (e) of Figure 27 are Ag K-edge XANES spectra, and (f) of Figure 27 is an Ag K-edge FT-EXAFS spectrum. Figure 28 is a diagram showing the In-situ XAS spectra of the Pt L3-edge for Comparative Example 1, Example 2, and Comparative Example 2. Specifically, (a), (d), and (g) of Figure 28 are the XANES spectra of Comparative Example 1, Example 2, and Comparative Example 2, respectively, (b), (e), and (h) of Figure 28 are the enlarged XANES spectra, respectively, and (c), (f), and (i) of Figure 28 are the FT-EXAFS spectra of Comparative Example 1, Example 2, and Comparative Example 2, respectively. Figure 29 is a diagram showing the platinum oxidation state according to the applied potential of Comparative Example 1, Example 2, and Comparative Example 2. Specifically, derived from the data according to Figure 28, (a) of Figure 29 shows the change in the oxidation number of platinum, and (b) of Figure 29 is a diagram showing the Pt-O formation profile.

[0195] Referring to (a) and (b) of Figure 27, in the case of Comparative Example 1, the white line peak is at 11568.0 eV, which is a peak position similar to that of PtO2. In the case of Example 2, it is at 11567.2 eV. In the case of Comparative Example 2, it is at 11566.7 eV, which is almost the same peak position as that of Pt foil. Thus, it can be seen that the composite according to one embodiment has a low oxidation state of platinum and an increased metallic platinum component by including silver (Ag) particles.

[0196] Referring to Fig. 27(c), in the case of Comparative Example 1, it has Pt - O and Pt - Pt radial distances of 1.70 A and 2.73 A respectively, and in the case of Example 2, it has a Pt - Pt radial distance of 2.65 A similar to that of Pt foil (2.64 A). In contrast, in the case of Comparative Example 2, due to the alloying effect, it has a longer Pt - Pt radial distance of 2.72 A.

[0197] Referring to Fig. 27(d) and Fig. 27(e), it can be seen that all samples have white line peaks at similar positions and have similar Ag oxidation states. Referring to Fig. 27(f), in the case of Comparative Example 2, similarly, due to the alloying effect, it can be seen that it has an Ag - Ag radial distance of 2.70 A shifted compared to Example 2 (2.60 A) and Comparative Example 3 (2.61 A).

[0198] Referring to Fig. 29(a), in the case of Example 2, it has a Pt oxidation number similar to that of Comparative Example 1 at OCV, but has a lower Pt oxidation number in the potential range above OCV. It can be seen that the addition of silver (Ag) actually plays a key role in suppressing the oxidation of platinum (Pt). On the other hand, in the case of Comparative Example 2, it shows a much lower platinum (Pt) oxidation state in the applied potential range, indicating that the alloyed silver (Ag) can also play the role of a sacrificial substance. However, Comparative Example 2 in alloy form shows a lower ORR activity compared to the composite with independently loaded silver (Ag) particles because the silver (Ag) present on the surface partially covers the active sites of platinum (Pt).

[0199] Referring to Fig. 29(b), Comparative Example 1 shows a much increased Pt-O interaction energy compared to Example 2 and Comparative Example 2. In Example 2 and Comparative Example 2, the tendency to form Pt-O is further reduced by the sacrificial role of silver that oxidizes prior to platinum. However, as can be seen from Fig. 9, the elution of silver in Comparative Example 2 has a low binding energy of silver and is much faster than in Example 2. This confirms that silver (Ag) particles supported on the carbon support independently of platinum (Pt) particles are more suitable and efficient for suppressing the oxidation and elution of platinum. As a result, in the composite according to one embodiment, since the active metal particles and the sacrificial metal particles exist independently, the sacrificial metal particles can play a better role as a sacrificial agent, and the oxidation problem of the active metal can be essentially solved.

[0200] (Experimental Example 6) Characterization of Gas Diffusion Layer To analyze the characteristics of the gas diffusion layer, a scanning electron microscope (SEM, Magellan400, FEI Company), energy-dispersive X-ray spectroscopy (EDS, FEI Themis Z), X-ray diffraction (XRD, Rigaku Smartlab, 4 kV, 15 mA, 4° min -1 , Cu-Kα radiation, λ = 1.55406 Å), and X-ray photoelectron spectroscopy (XPS, Kratos, AXIS-NOVA, 2.6×10 -9 torr) were used.

[0201] FIG. 33 is a diagram showing scanning electron microscope (SEM) images of the gas diffusion layers of Comparative Example 4 and Example 4. Specifically, FIGS. 33(a) and 33(b) are images of the commercial gas diffusion layer of Comparative Example 4, and FIGS. 33(c) and 33(d) are images of the gas diffusion layer manufactured in Example 4. FIG. 34 is a diagram showing the SEM image and the EDS mapping image of the gas diffusion layer of Comparative Example 4, and FIG. 35 is a diagram showing the SEM image and the EDS mapping image of the gas diffusion layer of Example 4. FIG. 36(a) is a diagram showing the X-ray diffraction (XRD) patterns of the gas diffusion layers of Comparative Example 4 and Example 4, and FIG. 36(b) is a diagram showing the Ag 3d XPS spectra of the gas diffusion layers of Comparative Example 4 and Example 4.

[0202] Referring to FIG. 33, in the case of Comparative Example 4, a porous network structure assembled with randomly distributed carbon fibers is observed, and in the case of Example 4, white particles formed on the carbon fibers of the porous network structure are observed. Referring to FIGS. 34 and 35, in the case of Example 4, it can be seen that silver (Ag) particles are randomly distributed on the carbon fibers. Referring to FIG. 36(a), in the case of Example 4, different from Comparative Example 4, peaks at (111) plane (38°) and (200) plane (44°) corresponding to the face centered cubic (fcc) silver (Ag) crystal structure are observed. Referring to FIG. 36(b), in the case of Example 4, different from Comparative Example 4, the peaks of Ag 3d 3 / 2 and Ag 3d 5 / 2 for Ag 0 are observed at 374 eV and 368 eV, respectively. From this, it can be seen that the white particles observed in the gas diffusion layer of Example 4 are silver (Ag) metal.

[0203] (Experimental Example 7) Characteristic Analysis of Fuel Cell Containing Membrane Electrode Assembly Using the membrane electrode assemblies fabricated in Example 5 and Comparative Example 5 respectively, the performance of a Proton Exchange Membrane Fuel Cell (PEMFC) was evaluated. Specifically, a proton exchange membrane fuel cell was supplied with pure hydrogen at a relative humidity of 100% at a flow rate of 300 sccm to the anode, and pure oxygen at a relative humidity of 100% at a flow rate of 1000 sccm to the cathode, and operated under a back pressure of 80 °C, 0.5 bar and constant current conditions.

[0204] To evaluate the durability of the catalyst, an Accelerated Durability Test (ADT) was conducted based on the 30,000 (30k) cycle Cyclic Voltammetry (CV) method proposed by the U.S. Department of Energy (DOE). Recently, as proposed in the M2FCT (Million Mile Fuel Cell Truck) protocol, the ADT was further extended to 90,000 (90k) cycles. According to the electric catalyst ADT cycle protocol, at 80 °C and ambient pressure, while supplying pure hydrogen at a relative humidity of 100% at a flow rate of 100 sccm to the anode and pure nitrogen at a relative humidity of 100% at a flow rate of 50 sccm to the cathode, both potentials were held for 3 seconds and performed between 0.6 V and 1.0 V. The rise time between both potentials was set to 0.5 seconds.

[0205] Figure 37 is a diagram illustrating polarization curves according to the ADT cycle of fuel cells to which Example 5 and Comparative Example 5 were applied. Specifically, polarization curves were measured at the initial stage before ADT execution, 30,000 (30k) cycles, 60,000 (60k) cycles, and 90,000 (90k) cycles.

[0206] The maximum power density (P max ), current density (j 0.2V ) at 0.2 V, and activity per unit mass (MA 0.9V) The values and the retention rates of each performance with respect to the initial values are summarized in Table 1.

[0207]

Table 1

[0208] Referring to Table 1, it can be seen that there is no significant difference between Comparative Example 5 and Example 5 before the ADT execution. On the other hand, after the ADT was performed, the performance of the fuel cell in Comparative Example 5 significantly decreased, while the performance of the fuel cell in Example 5 almost maintained its initial performance.

[0209] FIG. 38 is a diagram illustrating the measurement results of Electrochemical Impedance Spectroscopy (EIS) by the ADT cycle of the fuel cells to which Example 5 and Comparative Example 5 are applied. Here, the electrochemical impedance spectroscopy was measured at a cell current of 100 mA / cm 2 . Referring to FIG. 38(a) showing the results of Comparative Example 5, after 30,000 (30k) cycles, it increased from 0.912 Ω·cm 2 to 1.35 Ω·cm 2 , and after 90,000 (90k) cycles, it increased to 1.58 Ω·cm 2 . On the other hand, referring to FIG. 38(b) showing the results of Example 5, after 30,000 (30k) cycles, it increased from 0.912 Ω·cm 2 to 1.00 Ω·cm 2 , and after 90,000 (90k) cycles, it increased to 1.24 Ω·cm 2 , indicating that the charge transfer resistance significantly decreased compared to Comparative Example 5.

[0210] FIG. 39 is a diagram illustrating CV curves according to the ADT cycle of fuel cells to which Example 5 and Comparative Example 5 are applied. Referring to FIG. 39, in the case of Comparative Example 5, the electrochemical active surface area (ECSA) maintains only 31.7% and 8.6% of the initial values after 30,000 (30k) and 90,000 (90k) cycles, respectively, while in the case of Example 5, 100% and 47.1% are maintained.

[0211] From this, it can be seen that the membrane electrode assembly of the present invention and the fuel cell including the same have the merit that the durability of the catalyst is remarkably improved by including the sacrificial metal particle-containing gas diffusion layer. Specifically, even after the accelerated durability test (ADT) under severe conditions, the maintenance rates of the electrochemical active surface area (ECSA), maximum power density, current density, and activity per unit mass are high, and the increase in charge transfer resistance can be significantly reduced.

[0212] To explain such performance improvement, after performing ADT, the cathode catalyst layer and the cathode gas diffusion layer were analyzed.

[0213] FIG. 40 is a diagram illustrating Pt 4f X-ray photoelectron spectroscopy (XPS) spectra measured before and after performing ADT on the cathode catalyst layer included in the membrane electrode assemblies fabricated in Comparative Example 5 and Example 5. In the Pt 4f XPS spectrum, it is deconvoluted into two peaks corresponding to Pt 0 and Pt 2+ . For example, in the case of Pt 4f 7 / 2 for Pt 0 , it has ~71.9 eV, and in the case of Pt 2+ , it has ~72.9 eV. Referring to FIG. 40, in the case of Comparative Example 5, as the ADT cycle increases, the peak intensity of Pt 2+ gradually decreases, while for Pt 0The peak intensity shows a tendency to gradually increase. This is presumably because the size of the platinum (Pt) metal particles increases, the surface area of platinum (Pt) decreases, and the catalytic activity is significantly lost. In the case of Example 5, similar to Comparative Example 5, as the number of ADT cycles increases, Pt 2+ and Pt 0 show the same tendency of the peak intensity decreasing / increasing, but it can be seen that the rate of decrease or increase is significantly less than that of Comparative Example 5. Specifically, in the case of Comparative Example 5, the ratio (I2 / I1) of the Pt(II) peak intensity (I2) after the 90,000-cycle accelerated durability test to the Pt(II) peak intensity (I1) before the accelerated durability test is calculated to be 0.41. In the case of Example 5, the above-mentioned ratio of peak intensities (I2 / I1) is calculated to be 0.71, and it is confirmed that the rate of decrease in the peak intensity of Pt 2+ is less in Example 5 than in Comparative Example 5.

[0214] Fig. 41(a) is a diagram showing the XRD pattern of the gas diffusion layer included in the membrane electrode assembly fabricated in Example 5 according to the number of ADT cycles, and Fig. 41(b) is a diagram showing the Ag 3d XPS spectrum.

[0215] Referring to Fig. 41, the silver (Ag) particles included in the gas diffusion layer significantly decrease after 30,000 (30k) cycles and almost disappear after 90,000 (90k) cycles. Specifically, referring to Fig. 41(b), the peak intensity of Ag 3d 5 / 2 after 30,000 (30k) cycles is 15.0% of the initial peak intensity and completely disappears after 90,000 (90k) cycles. To confirm the more accurate amount of silver (Ag) reduction, ICP-OES analysis was further performed. As a result, after 30,000 (30k) cycles, the amount of silver (Ag) is 0.13 mg / cm 2 , which is 13% of the initial loading amount (1 mg / cm 2 ), and no signal was detected after 90,000 (90k) cycles. Thereby, the metallic silver (Ag) included in the gas diffusion layer becomes Ag +In contrast, it is oxidized and etched in the electrolytic solution, while platinum (Pt), which is an active metal, remains as metallic Pt by the sacrifice of silver (Ag) during the ADT cycle.

[0216] Figure 42(a) shows a transmission electron microscope (TEM, FEI Tecnai G2 twin) image of the catalyst layer included in Comparative Example 5 or Example 5 before performing ADT. Figures 42(b) and 42(c) show TEM images of the catalyst layer included in Comparative Example 5 after 30,000 (30k) and 90,000 (90k) cycles, respectively. Figures 42(d) and 42(e) show TEM images of the catalyst layer included in Example 5 after 30,000 (30k) and 90,000 (90k) cycles, respectively. Referring to Figure 42(a), before performing ADT, platinum (Pt) particles have a size of 2 to 3 nm and a uniform size distribution, and the average particle size at this time is 2.5 nm. Referring to Figures 42(b) and 42(c), the size of platinum (Pt) particles increases significantly to 5 to 50 nm, and the average particle sizes after 30,000 (30k) and 90,000 (90k) cycles at this time are 10 nm and 15 nm, respectively. Such an increase in the size of platinum (Pt) particles is due to the dissolution and aggregation of platinum (Pt), which is a major cause of the performance degradation of the fuel cell. On the other hand, referring to Figures 42(d) and 42(e) regarding Example 5, even after performing ADT, the changes in the size and size distribution of platinum (Pt) particles are significantly less than those in Comparative Example 5, and the average particle sizes after 30,000 (30k) and 90,000 (90k) cycles at this time are ~3 nm and ~4.5 nm, respectively. The reason for such results is that by including silver (Ag) particles in the gas diffusion layer, the active metal particles in the catalyst layer can be prevented from oxidizing and aggregating.

[0217] Figure 43 is a diagram showing a high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM, FEI Themis Z) image, the EDS mapping image, and the EDS spectrum of the catalyst layer included in Example 5 after 90,000 (90k) cycles. Figure 44 is a diagram showing the Ag 3d XPS spectrum of the catalyst layer included in Example 5 by ADT cycles.

[0218] Referring to FIGS. 43 and 44, it can be seen that silver (Ag) ions formed by oxidation during ADT do not deposit on or form an alloy with the active metal particles contained in the catalyst layer, and no silver (Ag) is observed on the catalyst layer after ADT.

[0219] As described above, in this specification, the present disclosure has been described by specific matters and limited examples, but this is provided to contribute to a more general understanding of the present disclosure, and the present disclosure is not limited to the above-described examples. Those having ordinary knowledge in the field to which the present disclosure pertains can make various modifications and variations from such descriptions.

[0220] Therefore, the idea described in this specification should not be defined only by the described examples, and not only the scope of the following claims, but also all those having modifications equivalent or equivalent to the scope of the present claims belong to the scope of the idea described in this specification.

Explanation of Reference Numerals

[0221] 10 First gas diffusion layer 20 First catalyst layer 30 Polymer electrolyte membrane 1 Support for the first gas diffusion layer 2 Sacrificial metal particles

Claims

1. A carbon support, active metal particles, and sacrificial metal particles that are oxidized or reduced in place of the active metal particles, A composite material, wherein the active metal particles and the sacrificial metal particles are independently supported on the carbon support.

2. The composite of claim 1 , wherein the active metal particles and the sacrificial metal particles are not alloyed with each other.

3. 2. The composite of claim 1, wherein the active metal particles comprise one or more metals selected from the group including palladium (Pd), platinum (Pt), gold (Au), ruthenium (Ru), rhodium (Rh), iridium (Ir), osmium (Os), and alloys comprising the same.

4. 2. The composite of claim 1, wherein the sacrificial metal particles contain a metal having a lower standard reduction potential than the active metal particles contain a metal.

5. 10. The composite of claim 1, wherein the sacrificial metal particles comprise one or more metals selected from the group including silver (Ag), palladium (Pd), iridium (Ir), ruthenium (Ru), rhodium (Rh), platinum (Pt), osmium (Os), iron (Fe), aluminum (Al), and alloys comprising the same.

6. The average particle size (D) of the active metal particles after 30,000 cycles of accelerated durability testing of the composite ２ ) and the average particle size (D １ ) and the ratio (D ２ / D １ 2. The complex of claim 1, wherein n is 0 or less.

7. 2. The composite according to claim 1, wherein the atomic ratio of the sacrificial metal contained in the sacrificial metal particles to the active metal contained in the active metal particles is 1:0.1 to 1:

50.

8. The active metal contained in the active metal particles includes platinum (Pt), 2. The composite according to claim 1, wherein the difference in 2θ value between the maximum peak appearing in the range of 2θ = 39.8 ± 1.0 ° in the X-ray diffraction (XRD) spectrum of the composite and pure platinum (Pt) is 0.3 ° or less.

9. The active metal contained in the active metal particles includes platinum (Pt), The composite was analyzed by X-ray photoelectron spectroscopy (XPS) to determine Pt 4f ７／２ The Pt(0) peak intensity (I ０ ) and Pt(II) peak intensity (I ＩＩ ) and the ratio (I ０ / I ＩＩ 2. The composite of claim 1, wherein the σ is 1.8 or more.

10. A step of mixing a dispersion containing a carbon support having active metal particles supported thereon and a solution containing a sacrificial metal precursor to produce a first reaction solution; adding a reducing agent to the first reaction solution to synthesize a composite in which the active metal particles and sacrificial metal particles are independently supported on the carbon support.

11. A step of mixing a dispersion liquid containing a carbon support on which active metal particles are supported and a dispersion liquid containing a carbon support on which sacrificial metal particles are supported to produce a second reaction solution; adding a reducing agent to the second reaction solution to synthesize a composite in which the active metal particles and the sacrificial metal particles are independently supported on a carbon support.

12. a cathode including a first catalyst layer and a first gas diffusion layer, an anode including a second catalyst layer and a second gas diffusion layer, and a polymer electrolyte membrane disposed between the cathode and the anode; the first catalyst layer includes active metal particles; the first gas diffusion layer comprises a first gas diffusion layer support and sacrificial metal particles supported on the first gas diffusion layer support and oxidized or reduced in place of the active metal particles.

13. The membrane electrode assembly according to claim 12 , wherein a surface of the first gas diffusion layer support on which the sacrificial metal particles are located faces a surface of the first catalyst layer.

14. the second catalyst layer includes active metal particles; 13. The membrane electrode assembly according to claim 12, wherein the second gas diffusion layer comprises a second gas diffusion layer support and sacrificial metal particles supported on the second gas diffusion layer support and oxidized or reduced in place of the active metal particles.

15. 13. The membrane electrode assembly of claim 12, wherein the active metal particles comprise one or more metals selected from the group consisting of palladium (Pd), platinum (Pt), gold (Au), ruthenium (Ru), rhodium (Rh), iridium (Ir), osmium (Os), and alloys comprising any of the foregoing.

16. 13. The membrane electrode assembly of claim 12, wherein the metal contained in the sacrificial metal particles has a lower standard reduction potential than the metal contained in the active metal particles.

17. 13. The membrane electrode assembly of claim 12, wherein the sacrificial metal particles comprise one or more metals selected from the group including silver (Ag), palladium (Pd), iridium (Ir), ruthenium (Ru), rhodium (Rh), platinum (Pt), osmium (Os), iron (Fe), aluminum (Al), and alloys comprising any of the foregoing.

18. The average particle size of the active metal particles after 30,000 cycles of accelerated durability testing (D ２ ) and the average particle size of the active metal particles before the accelerated durability test (D １ ) and the ratio (D ２ / D １ 13. The membrane electrode assembly of claim 12, wherein n is 3 or less.

19. 13. The membrane electrode assembly according to claim 12, wherein an atomic ratio of the sacrificial metal contained in the sacrificial metal particles contained in the first gas diffusion layer to the active metal contained in the active metal particles contained in the first catalyst layer is 0.1:1 to 100:

1.

20. The active metal contained in the active metal particles includes platinum (Pt), The first catalyst layer has a Pt(II) peak intensity (I) of 90,000 cycles after an accelerated durability test in a Pt 4f XPS spectrum by X-ray photoelectron spectroscopy (XPS). ２ ) and the Pt(II) peak intensity before and after the accelerated durability test (I １ ) and the ratio (I ２ / I １ 13. The membrane electrode assembly according to claim 12, wherein the n-th order is 0.5 or more.

21. The content of the sacrificial metal particles per unit area of ​​the first gas diffusion layer support is 0.1 to 100 mg / cm ２ The membrane electrode assembly according to claim 12 ,

22. A first step of doping a sacrificial metal precursor onto a support for a first gas diffusion layer; A second step of reducing the sacrificial metal precursor doped on the first gas diffusion layer support to produce a first gas diffusion layer having sacrificial metal particles supported on the first gas diffusion layer support; a third step of forming a first catalyst layer on one side of the polymer electrolyte membrane; a fourth step of forming a second catalyst layer on the other surface of the polymer electrolyte membrane; a fifth step of forming the first gas diffusion layer on the first catalyst layer; and a sixth step of forming a second gas diffusion layer on the second catalyst layer.

23. An electrode for a fuel cell comprising the composite of claim 1.

24. A fuel cell comprising the membrane electrode assembly according to claim 12 or the fuel cell electrode according to claim 23.

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