Carbon supports for fuel cell catalysts, catalysts including such supports, membrane-electrode assemblies including such supports, and methods for their preparation.

Abstract

This invention discloses a carbon-based support, a catalyst comprising the carbon-based support, a membrane-electrode assembly comprising the carbon-based support, and a method for manufacturing the carbon-based support. This carbon-based support can improve catalytic activity to a similar degree as porous supports while possessing the excellent durability characteristic of solid-type supports. The carbon-based support for fuel cell catalysts of this invention is a solid-type support with a thickness of 100 to 450 μm. 2 External surface area per g, 0.25 to 0.65 cm² 3 / g of mesopore volume and 0.01 to 0.05 cm³ 3 / g micropore volume.

Description

Technical Field

[0001] This invention relates to a carbon-based support for fuel cell catalysts, a catalyst comprising the carbon-based support for fuel cell catalysts, a membrane electrode assembly comprising the ... Background Technology

[0002] Polymer electrolyte membrane fuel cells (PEMFCs) that generate electricity using a stacked structure of cell units are attracting attention as a next-generation energy source capable of replacing fossil fuels due to their high energy efficiency and environmental friendliness. Each cell unit includes a membrane electrode assembly (MEA) and a separator (also known as a “bipolar plate”).

[0003] A membrane-electrode assembly typically includes an anode (also known as a "fuel electrode"), a cathode (also known as an "air electrode"), and a polymer electrolyte membrane disposed between them.

[0004] When fuel such as hydrogen is supplied to the anode, the hydrogen at the anode is oxidized to produce protons (H). + ) and electrons (E - The protons produced are transferred to the cathode through a polymer electrolyte membrane (PEM), while the electrons produced are transferred to the cathode through an external circuit. Oxygen supplied to the cathode combines with the protons and electrons and is thus reduced, producing water.

[0005] In an attempt to increase the active surface area of ​​catalysts used to form membrane-electrode assemblies, catalysts have been developed in which catalyst metal particles are dispersed on the surface of a carbon-based support with electrical conductivity.

[0006] This type of carbon support can be divided into solid supports (e.g., acetylene black) and porous supports (e.g., furnace black).

[0007] Compared to porous supports, solid supports exhibit superior durability, but their specific surface area is relatively low. The low specific surface area of ​​the support limits the number of catalyst metal particles that can be dispersed on it, thus imposing limitations on increasing the active surface area of ​​the catalyst.

[0008] To overcome this limitation, studies have been conducted to increase the specific surface area of ​​solid carbon-based supports. For example, as a method for increasing the specific surface area of ​​solid carbon-based supports, Korean Patent Publication No. 10-2012-0021408 (hereinafter referred to as "Prior Art") discloses heat treatment of the support in a steam atmosphere. However, catalysts with satisfactory active surface areas cannot be prepared using supports heat-treated by this method.

[0009] As a result of ongoing research into the reasons for the limitations of existing technologies, it has been found that the heat treatment proposed in the prior art can significantly increase the surface area and volume of both micropores and mesopores in the carrier, but cannot selectively increase only the surface area and volume of mesopores. Here, the term "mesopore" refers to a pore with a diameter of 2 nm to 50 nm, while the term "micropore" refers to a pore with a diameter of less than 2 nm.

[0010] However, typically, catalyst metal particles dispersed on a support and entering the mesopores contribute to catalytic activity, while those entering the micropores contribute little or no to catalytic activity. Furthermore, mesopores are better able to improve the mass transfer capacity of the catalyst compared to micropores. For this reason, solid carbon supports that have undergone heat treatment according to existing techniques (i.e., having more micropores than mesopores) cannot provide sufficient active surface area and improved mass transfer capacity for the catalyst.

[0011] Therefore, the most important thing is to find the heat treatment conditions for solid carbon supports that can selectively increase only the number of mesopores rather than the number of micropores. Summary of the Invention

[0012] Technical issues

[0013] Therefore, the present invention relates to a carbon support for a fuel cell catalyst, a catalyst including the support, a membrane electrode assembly including the support, and a method for manufacturing the support, which can prevent problems caused by the limitations and disadvantages of the prior art described above.

[0014] One aspect of the present invention is to provide a carbon-based support for fuel cell catalysts, which, while possessing the excellent durability characteristic of solid supports, can also improve catalytic activity to the same extent as porous supports due to its increased surface area and mesopore volume.

[0015] Another aspect of the present invention is to provide a catalyst for fuel cells, which exhibits excellent durability and high catalytic activity due to the increased mesopores of the support, which improves the dispersion of catalyst metal particles.

[0016] Another aspect of the present invention is to provide a membrane electrode assembly with excellent performance and excellent durability.

[0017] Another aspect of the present invention is to provide a method for producing a carbon-based support for fuel cell catalysts, which, while possessing the excellent durability characteristic of solid supports, can also improve catalytic activity to the same extent as porous supports due to its increased surface area and mesopore volume.

[0018] In addition to the foregoing aspects of the invention, other features and advantages of the invention will be clearly understood by those skilled in the art to which this invention pertains, as will be described in the following detailed description.

[0019] Technical solution

[0020] According to the present invention, the above and other objectives can be achieved by a carbon-based support for a fuel cell catalyst, wherein the carbon-based support is a solid support and has a density of 100 μm. 2 / g to 450m 2 / g external surface area, 0.25cm 3 / g to 0.65cm 3 / g of mesopore volume and 0.01cm 3 / g to 0.05cm 3 / g micropore volume. Each of the external surface area, mesopore volume, and micropore volume is the arithmetic mean of measurements obtained from five randomly selected samples using a Brunauer-Emmett-Teller (BET) analyzer (micrometer level, ASAP-2020).

[0021] Carbon-based supports can have a thickness of 150m 2 / g to 600m 2 / g of BET surface area, where the BET surface area is the arithmetic mean of measurements obtained from five randomly selected samples using a BET analyzer.

[0022] Carbon-based supports can have to The d-interval values ​​are calculated using Bragg's law based on the (002) peak obtained through XRD analysis.

[0023] Carbon-based carriers can be acetylene black carriers.

[0024] According to another aspect of the present invention, a catalyst is provided, comprising a carbon support and catalyst metal particles dispersed on the carbon support.

[0025] According to another aspect of the present invention, a membrane-electrode assembly is provided, comprising: an anode; a cathode; and a polymer electrolyte membrane disposed between the anode and the cathode; wherein at least one of the anode and the cathode comprises a catalyst.

[0026] According to another aspect of the present invention, a method for manufacturing a carbon-based support is provided, the method comprising preparing a solid carbon-based raw material support; and subjecting the raw material support to heat treatment such that the support activated by the heat treatment satisfies the following formulas 1 to 3:

[0027] [Formula 1]

[0028] S EX_AS ≥S EX_RS ×3

[0029] [Equation 2]

[0030] V MESO_AS ≥V MESO_RS ×1.2

[0031] [Formula 3]

[0032] V MICRO_AS ≤V MICRO_RS ×1.1

[0033] Among them, S EX_AS It is the surface area of ​​the activation carrier, S EX_RS V is the outer surface area of ​​the raw material carrier. MESO_AS V is the mesopore volume of the activation carrier. MESO_RS V is the volume of the mesopores in the raw material carrier. MICRO_AS It is the micropore volume of the activation support, and V MICRO_RS It is the micropore volume of the raw material carrier.

[0034] Each of the external surface area, mesopore volume, and micropore volume is the arithmetic mean of measurements obtained from five randomly selected samples using a BET analyzer (Micromeritics, ASAP-2020).

[0035] The activated support can be heat-treated in a manner that further satisfies Equation 4 below:

[0036] [Formula 4]

[0037] S BET_AS ≥S BET_RS ×2

[0038] Among them, S BET_AS It is the BET surface area of ​​the activated carrier, S BET_RS It is the BET surface area of ​​the raw material carrier.

[0039] BET surface area (S)BET The result is the arithmetic mean of measurements obtained from five randomly selected samples using a BET analyzer.

[0040] Heat treatment can be performed in a manner that allows the activated support to further satisfy equations 5 and 6 below:

[0041] [Formula 5]

[0042] DS AS ≤DS RS ×1.1

[0043] [Formula 6]

[0044] I AS ≥I RS ×0.5

[0045] Among them, DS AS The d-interval value is calculated using Bragg's law based on the (002) peak obtained through XRD analysis of the activated support. RS The d-interval value is calculated using Bragg's law based on the (002) peak obtained through XRD analysis of the raw material carrier. AS The intensity of the (002) peak was obtained through XRD analysis of the activated support, and I RS The intensity of the (002) peak is obtained through XRD analysis of the raw material carrier.

[0046] The method may further include performing a thermogravimetric analysis of the raw material carrier prior to heat treatment and determining a first temperature at which a 20% weight loss occurs based on the results of the thermogravimetric analysis, wherein heat treatment is carried out in air at a second temperature satisfying Equation 7 below:

[0047] [Formula 7]

[0048] T1–40℃≤T2≤T1+40℃

[0049] Where T1 is the first temperature and T2 is the second temperature.

[0050] The raw material carrier may include acetylene black.

[0051] The general description of this invention is for illustrative purposes only and does not limit the scope of the invention.

[0052] Beneficial effects

[0053] This invention provides a carbon-based support. By heat-treating a solid carbon-based support under specific conditions, the catalytic activity can be improved to the same extent as that of a porous support while exhibiting the excellent durability unique to solid supports. The specific conditions enable the surface area and volume of mesopores, which can greatly contribute to improving catalytic activity, to increase more than the surface area and volume of micropores.

[0054] According to the present invention, catalysts for fuel cells with excellent durability and high-quality catalytic activity can also be provided.

[0055] The present invention can also provide membrane-electrode components with excellent performance and high durability. Attached Figure Description

[0056] The accompanying drawings are provided to better understand the invention and form part of this specification. The drawings are provided to illustrate embodiments of the invention and, together with the following detailed description, to explain the principles and features of the invention, wherein:

[0057] Figure 1 This is a graph showing the results of thermogravimetric analysis (TGA) of three types of raw material acetylene black carrier;

[0058] Figure 2 These are the XRD patterns of the raw material acetylene black carrier and the activated acetylene black carrier of Example 1;

[0059] Figure 3 This is a graph showing the BET isotherm curves of each of the raw material acetylene black carrier and the activated acetylene black carrier in Example 1.

[0060] Figure 4 This is a graph showing the pore distribution curves of each of the raw material acetylene black carrier and the activated acetylene black carrier in Example 1.

[0061] Figure 5 (a) and (b) are transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HR-TEM) images showing the catalyst produced using the activated acetylene black support of Example 1. Detailed Implementation

[0062] In the following description, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the following embodiments are provided only for a clear understanding of the present invention and do not limit the scope of the invention.

[0063] The carbon support for fuel cells of the present invention is essentially a solid support. According to embodiments of the present invention, the solid carbon support can have any shape selected from the group consisting of spheres, polyhedra, and ovals.

[0064] As mentioned above, solid carriers such as acetylene black have superior durability but lower specific surface area compared to porous carriers such as furnace black.

[0065] As described in this article, the term "solid carrier" is defined as having a density of 450m. 2 External surface area below / g and 0.05cm 3A carrier with a micropore volume of less than 450 μg, wherein the external surface area and micropore volume are measured by the BET measurement method, is defined as a carrier with a micropore volume greater than 450 μg. 2 The external surface area per g is greater than 0.05 cm². 3 The carrier has a micropore volume of / g, wherein the external surface area and micropore volume are measured by the BET measurement method.

[0066] This invention provides a carbon-based support that, by heat-treating a solid-type carbon-based support under specific conditions that significantly increase the surface area and volume of mesopores compared to micropores (i.e., selectively and substantially increasing only the surface area and volume of mesopores), can exhibit excellent durability comparable to that of solid-type supports while simultaneously improving catalytic activity to that of porous supports. As described above, "mesopores" refers to pores with a diameter of 2 to 50 nm, and "micropores" refers to pores with a diameter less than 2 nm.

[0067] Specifically, the method for manufacturing the carbon-based support of the present invention includes preparing a solid carbon-based raw material support (e.g., acetylene black) and subjecting the raw material support to heat treatment under specific conditions.

[0068] Specific conditions can be conditions that enable the heat-activated support to satisfy the following equations 1 to 3:

[0069] [Formula 1]

[0070] S EX_AS ≥S EX_RS ×3

[0071] [Equation 2]

[0072] V MESO_AS ≥V MESO_RS ×1.2

[0073] [Formula 3]

[0074] V MICRO_AS ≤V MICRO_RS ×1.1

[0075] Among them, S EX_AS It is the surface area of ​​the activation carrier, S EX_RS V is the outer surface area of ​​the raw material carrier. MESO_AS V is the mesopore volume of the activation carrier. MESO_RS V is the volume of the mesopores in the raw material carrier. MICRO_AS V is the micropore volume of the activation carrier. MICRO_RS It is the micropore volume of the raw material carrier.

[0076] In other words, according to the manufacturing method of the present invention, the outer surface area (S) of the carrier is mainly determined by the central hole.EX The mesopore volume (V) of the carrier can be increased more than three times through heat treatment. MESO Heat treatment increases the micropore volume (V) of the carrier by more than 1.2 times. MICRO Heat treatment increases the yield by less than 1.1 times.

[0077] Specifically, the carbon-based support according to the present invention, heat-treated under the aforementioned specific conditions, has a density of 100 to 450 μm. 2 / g of external surface area (S) EX_AS ), 0.25 to 0.65 cm 3 / g mesopore volume (V MESO_AS ) and 0.01 to 0.05 cm 3 / g micropore volume (V MICRO_AS ).

[0078] Specific conditions may be required for the heat-activated support to further satisfy the following equation 4:

[0079] [Formula 4]

[0080] S BET_AS ≥S BET_RS ×2

[0081] Among them, S BET_AS It is the BET surface area of ​​the activated carrier, S BET_RS It is the BET surface area of ​​the raw material carrier.

[0082] In other words, according to the manufacturing method of the present invention, the preferred method is to use a carrier with a BET surface area (S) induced by heat treatment. BET The increase should be more than twice, and this increase should be less than the increase in external surface area (S). EX The increase of ).

[0083] For example, a carbon support according to an embodiment of the present invention, heat-treated under specific conditions, can have a thickness of 150 to 600 μm. 2 / g of BET surface area (S BET_AS ).

[0084] In this invention, the outer surface area (S) EX ), mesopore volume (V) MESO ), BET surface area (S BET ) and micropore volume (V MICRO Each of the values ​​is the arithmetic mean of measurements obtained from five randomly selected samples using a BET analyzer (Micromeritics, ASAP-2020). According to BET analysis, the physical properties of the sample are measured based on the Brunauer-Emmett-Teller (BET) theory after a gas (usually nitrogen) is adsorbed onto the sample.

[0085] Specific conditions may be required to enable the heat-activated support to further satisfy the conditions in equations 5 and 6 below:

[0086] [Formula 5]

[0087] DS AS ≤DS RS ×1.1

[0088] [Formula 6]

[0089] I AS ≥I RS ×0.5

[0090] Among them, DS AS The d-interval value is calculated using Bragg's law based on the (002) peak obtained through XRD analysis of the activated support. RS The d-interval value is calculated using Bragg's law based on the (002) peak obtained through XRD analysis of the raw material carrier. AS The intensity of the (002) peak was obtained through XRD analysis of the activated support, and I RS The intensity of the (002) peak is obtained through XRD analysis of the raw material carrier.

[0091] For example, XRD analysis can be performed using the Shimadzu XRD analyzer (XRD-7000) under the following conditions.

[0092] -X-ray source:

[0093] - Voltage: 40kV

[0094] - Current: 30mA

[0095] In other words, in the manufacturing method according to an embodiment of the present invention, the preferred d-spacing value (DS) of the raw material carrier is... RS The value was 3.2997 to Furthermore, the d-spacing value (DSR) increases by a maximum of only 10%. Additionally, a (002) peak intensity (I) of the feed carrier is preferred. RS Heat treatment can reduce the temperature by up to 50%.

[0096] For example, the carbon support of the present invention, after heat treatment under the specific conditions described above, can exhibit an XRD pattern of 3.38 to [missing value] when subjected to XRD analysis under the same conditions. d-spacing value (DS) AS ).

[0097] To meet the above heat treatment conditions (multiple), heat treatment should first be carried out in air.

[0098] As described above, during heat treatment in a steam atmosphere, the surface area and volume of both micropores and mesopores increase rapidly. As also mentioned above, when catalyst metal particles are dispersed on a support, those entering the mesopores can contribute to the catalytic activity, while those entering the micropores contribute little or no to the catalytic activity. Therefore, the increase in the surface area and volume of micropores offsets the increase in catalytic activity caused by the increase in the surface area and volume of mesopores. Consequently, it is impossible to produce a catalyst with a satisfactory active surface area using a support heat-treated in a steam atmosphere.

[0099] Meanwhile, heat treatment in an inert gas atmosphere may result in unsatisfactory pore activation of the support. Therefore, supports heat-treated in an inert gas atmosphere may also lack sufficient external surface area (S). EX ) or mesopore volume (V MESO ).

[0100] Heat treatment temperature is also one of the key process factors for meeting the above heat treatment conditions (multiple), and it is a process factor that should be determined according to the type or physical properties of the raw material carrier.

[0101] Therefore, the method of the present invention may further include determining the heat treatment temperature based on the type and / or physical properties of the raw material carrier prior to heat treatment. More specifically, the method according to the present invention includes performing thermogravimetric analysis (TGA) on the raw material carrier prior to heat treatment and determining a first temperature at which a 20% weight loss occurs based on the results of the TGA. The heat treatment of the present invention can be performed at a second temperature satisfying Equation 7 based on the determined first temperature.

[0102] [Formula 7]

[0103] T1–40℃≤T2≤T1+40℃

[0104] Where T1 is the first temperature and T2 is the second temperature.

[0105] Figure 1 This is a graph showing the results of thermogravimetric analysis (TGA) of three raw material acetylene black carriers, from... Figure 1 It can be seen that rapid weight loss is observed starting from the point where a 20% weight loss occurs, and the first temperature (T1) at which this 20% weight loss occurs varies considerably depending on the type of acetylene black support. That is, at... Figure 1 In the example, the first temperature (T1) of the type A acetylene black carrier is about 500°C, the first temperature (T1) of the type B acetylene black carrier is about 519°C, and the first temperature (T1) of the type C acetylene black carrier is about 477°C.

[0106] As described above, the second temperature (T2) serving as the heat treatment temperature of the present invention can be a temperature within the range of T1 ± 40°C, and more specifically, a temperature within the range of T1 ± 20°C. When the second temperature (T2) serving as the heat treatment temperature is higher than T1 + 40°C, carbon oxidation occurs, resulting in a rapid increase in the surface area and volume of the mesopores and the micropores. Conversely, when the second temperature (T2) serving as the heat treatment temperature is lower than T1 - 40°C, the heat treatment effect is unsatisfactory, and therefore a sufficient increase in the surface area and volume of the mesopores cannot be expected.

[0107] According to an embodiment of the present invention, heat treatment can be performed at a second temperature T2 for 0.5 to 8 hours.

[0108] The catalyst of the present invention can be obtained by dispersing catalyst metal particles on the solid carbon support of the present invention obtained by heat treatment using conventional methods.

[0109] The catalyst metal particles may include platinum or platinum-based alloys. Platinum-based alloys are (i) binary alloys, such as Pt-Co, Pt-Pd, Pt-Mn, Pt-Sn, Pt-Mo, Pt-Cr, Pt-W, Pt-Ir, Pt-Ru, Pt-Ni, or Pt-Fe; and (ii) ternary alloys, such as Pt-Ru-W, Pt-Ru-Ni, Pt-Ru-Mo, Pt-Ru-Ir, Pt-Co-Mn, Pt-Co-Ni, and Pt-Co-F. e. Pt-Co-Ir, Pt-Co-S, Pt-Co-P, Pt-Fe-Ir, Pt-Fe-S, Pt-Fe-P, Pt-Au-Co, Pt-Au-Fe, Pt-Au-Ni, Pt-Ni-Ir or Pt-Cr-Ir; or (iii) quaternary alloys, such as Pt-Ru-Rh-Ni, Pt-Ru-Sn-W or Pt-Ru-Ir-Ni, but not limited thereto.

[0110] As described above, by heat-treating a solid carbon support under certain conditions, the surface area and volume of mesopores, which significantly contribute to improved catalytic activity, increase more than those of micropores. The carbon support of the present invention obtained through heat treatment exhibits excellent durability (durability is an inherent characteristic of solid supports) and can improve catalytic activity to the same level as that of porous supports. Therefore, the catalyst for fuel cells of the present invention, obtained by dispersing catalyst metal particles on the carbon support of the present invention, can possess high catalytic activity and excellent durability.

[0111] The method of forming an electrode and a membrane-electrode assembly including the electrode using the hybrid catalyst of the present invention will be described in detail below.

[0112] First, the catalyst prepared according to the present invention is dispersed together with the ionomer in a dispersion medium to prepare an electrode slurry.

[0113] The ionomer, dispersed in a dispersion medium along with the catalyst according to the invention, serves to transfer protons and also acts as a binder to improve the adhesion between the electrode and the polymer electrolyte membrane. The ionomer may be a fluorinated ionomer or a hydrocarbon ionomer, and may have at least one ion-conducting group selected from the group consisting of sulfonic acid, carboxyl, boric acid, phosphate, imide, sulfonylimide, sulfonamide, and sulfonyl fluoride.

[0114] For example, the ionomer can be a fluorinated ionomer, such as poly(perfluorosulfonic acid) or poly(perfluorocarboxylic acid).

[0115] Alternatively, the ionomer can be a hydrocarbon ionomer, such as sulfonated polyimide (S-PI), sulfonated polyarylene ether sulfone (S-PAES), sulfonated polyether ether ketone (SPEEK), sulfonated polybenzimidazole (SPBI), sulfonated polysulfone (S-PSU), sulfonated polystyrene (S-PS), sulfonated polyphosphazene, sulfonated polyquinoxaline, sulfonated polyketone, sulfonated polyphenylene oxide, sulfonated polyether sulfone, sulfonated polyether ketone, sulfonated polyphenylene sulfone, sulfonated polyphenylene sulfide, sulfonated polyphenylene sulfide sulfone, and sulfonated polyphenylene sulfide sulfone. nitrile), sulfonated polyarylene ether, sulfonated polyarylene ether nitrile, sulfonated polyarylene ether ether nitrile, or sulfonated polyarylene ethersulfone ketone.

[0116] The dispersion medium can be water, a hydrophilic solvent, an organic solvent, or a mixture of two or more of them.

[0117] Hydrophilic solvents can be compounds that contain a straight-chain or branched saturated or unsaturated hydrocarbon having 1 to 12 carbon atoms as the main chain and have at least one functional group selected from the group consisting of alcohols, ketones, aldehydes, carbonates, carboxylates, carboxylic acids, ethers and amides.

[0118] The organic solvent may be N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), dimethylacetamide (DMAc), or a mixture of two or more thereof, but is not limited thereto.

[0119] Subsequently, the substrate is coated with electrode paste, and then the coated electrode paste is dried.

[0120] In embodiments of the present invention, electrodes can be formed on a polymer electrolyte membrane using a decal transfer method.

[0121] According to the decal transfer method, the substrate coated with electrode paste is a release film, and the electrode formation method according to the present invention further includes transferring the electrode formed on the release film by drying to a polymer electrolyte membrane and removing the release film.

[0122] Specifically, an electrode paste is coated onto a release film using a mask to form a predetermined shape and size, and then the dispersion medium is removed from the electrode paste through a subsequent drying process. The release film and electrodes are then stacked onto a polymer electrolyte membrane, such that the electrodes formed in the drying process come into contact with the polymer electrolyte membrane. The electrodes are then transferred onto the polymer electrolyte membrane by hot pressing, after which the release film is removed.

[0123] When using the decal transfer method to manufacture membrane-electrode assemblies, typically the anode and cathode are formed on the release film in the same manner as described above, and the anode and cathode are simultaneously transferred to one surface and the other surface of the polymer electrolyte membrane.

[0124] The polymer electrolyte membrane can be a single membrane formed from an ionomer, or a reinforced composite membrane including a porous carrier impregnated with an ionomer. Preferably, the ionomer of the polymer electrolyte membrane and the ionomer of the electrode slurry are the same type of ionomer, but the invention is not limited thereto; different types of ionomers can be used in the manufacture of the polymer electrolyte membrane and the electrode.

[0125] In another embodiment of the invention, electrodes can be formed on a polymer electrolyte membrane by direct coating.

[0126] According to the direct coating method, the substrate coated with the electrode paste is a polymer electrolyte membrane. For example, a polymer electrolyte membrane is coated with a mask electrode paste in a predetermined shape and size, and a drying process is performed to remove the dispersion medium from the electrode paste. Subsequently, when the electrode is formed through the drying process, the mask is removed.

[0127] When using the direct coating method to manufacture membrane-electrode assemblies, the anode and cathode can be sequentially formed on one surface and the other surface of the polymer electrolyte membrane.

[0128] As described above, the membrane-electrode assembly (MEA) of the present invention can be manufactured by forming an anode and a cathode on one surface and another surface of a polymer electrolyte membrane, respectively, using an electrode paste by means of decal transfer printing or direct coating.

[0129] For example, the membrane-electrode assembly (MEA) of the present invention includes an anode, a cathode and a polymer electrolyte membrane therebetween, wherein at least one of the anode and cathode may include the catalyst of the present invention.

[0130] The invention will be described in more detail below with reference to specific examples. These examples are provided only for better understanding and should not be construed as limiting the scope of the invention.

[0131] Example 1

[0132] Thermogravimetric analysis (TGA) on the raw acetylene black carrier revealed that the first temperature (T1) at which a 20% weight loss occurred was 500°C. Then, a second temperature (T2) was set at 500°C within the range of T1 ± 40°C, and the raw acetylene black carrier was heat-treated for 5 hours. Specifically, a boat containing the raw carrier was placed in a furnace. The furnace temperature was increased to 500°C at a rate of 5°C / min in an air atmosphere, and the raw carrier was heat-treated for 5 hours to obtain a solid-type activated acetylene black carrier.

[0133] Comparative Example 1

[0134] Except for preparing the same type of raw material acetylene black carrier as in Example 1 (i.e., T1 = 500°C) and setting the second temperature (T2) as the heat treatment temperature to 550°C (= T1 + 50°C), the solid activated acetylene black carrier was obtained in the same manner as in Example 1.

[0135] Comparative Example 2

[0136] Except for preparing the same type of raw material acetylene black carrier as in Example 1 (i.e., T1 = 500°C), but setting the second temperature (T2) as the heat treatment temperature to 450°C (= T1 - 50°C), a solid activated acetylene black carrier was obtained in the same manner as in Example 1.

[0137] Comparative Example 3

[0138] Except for preparing the same type of raw material acetylene black carrier as in Example 1 (i.e., T1 = 500°C), but performing heat treatment in a steam atmosphere instead of an air atmosphere, a solid activated acetylene black carrier was obtained in the same manner as in Example 1.

[0139] [BET Analysis]

[0140] The physical properties of the raw acetylene black support and activated acetylene black support in Example 1 and the comparative example, namely the BET surface area (S), were measured using a BET analyzer (Micromeritics, ASAP-2020). BET ), micropore surface area (S) MICRO ), external surface area (S) EX Total pore volume (VT), micropore volume (V) MICRO ) and mesopore volume (V MESO Specifically, the physical properties of five samples randomly selected from each carrier were measured, and the arithmetic mean of the measured sample values ​​for each physical property was calculated. The results are shown in Table 1 below.

[0141] [XRD Analysis]

[0142] Using an XRD analyzer (Shimadzu, XRD-7000) [X-ray source: XRD analysis was performed on each of the raw acetylene black support and activated acetylene black support used in Example 1 and the Comparative Example. The d-spacing values ​​(DS) calculated using Bragg's law with the (002) peak are shown in Table 1 below. Additionally, the XRD patterns of the raw acetylene black support and activated acetylene black support from Example 1 are shown below. Figure 2 As shown.

[0143] [Table 1]

[0144]

[0145] As shown in Table 1, in Example 1, the outer surface area (S) of the central hole EX ) and mesopore volume (V MESO The surface area of ​​micropores (S) increased significantly, but the surface area of ​​micropores (S) MICRO ) and micropore volume (V MICROThe surface area and volume of the mesopores increased almost nothing (i.e., the surface area and volume of the mesopores increased significantly, but the surface area and volume of the micropores increased almost nothing). In contrast, in Comparative Examples 1 and 3, the external surface area (S) of the mesopores was significantly smaller. EX ) and mesopore volume (V MESO The surface area of ​​micropores (S) increased, but the surface area of ​​micropores (S) was also observed to increase. MICRO ) and micropore volume (V MICRO The surface area and volume of micropores increase significantly (i.e., the surface area and volume of mesopores increase as much as those of mesopores). As mentioned above, when catalyst metal particles are dispersed on a support, the catalyst metal particles entering the mesopores can contribute to the catalytic activity, while the catalyst metal particles entering the micropores contribute little or no to the catalytic activity. Considering this, the increase in the surface area and volume of micropores offsets the increase in catalytic activity caused by the increase in the surface area and volume of mesopores; therefore, it is difficult to expect an increase in catalytic activity through heat treatment of the support.

[0146] Furthermore, the d-spacing value (DS) of the activated acetylene black support in Examples 1 and 2 was not significantly different from that of the raw acetylene black support [for example, in Example 1, the d-spacing value (DS) increased by only about 0.6% after heat treatment], while the d-spacing value (Ds) of the activated acetylene black support in Comparative Examples 1 and 3 was much larger than that of the raw acetylene black support (i.e., the d-spacing value (Ds) increased significantly after heat treatment). This significant increase in the d-spacing value (DS) (e.g., an increase of more than 10%) indicates a significant change in the crystal structure of carbon.

[0147] from Figure 2 The XRD pattern shows that the (002) peak intensity (I) of Example 1 is more than 50% of the (002) peak intensity (I) of the raw material acetylene black carrier [that is, the (002) peak intensity (I) is reduced due to the activation being less than 50%].

[0148] Although not described in detail, activated acetylene black carriers obtained by heat-treating the raw material acetylene black carrier at temperatures within the range of T1±40℃ (i.e., 460℃, 480℃, 520℃ and 540℃) also showed similar results to the activated acetylene black carrier of Example 1.

[0149] [BET isotherm and orifice distribution curve]

[0150] The BET isotherms and pore distribution curves of the raw acetylene black support and the activated acetylene black support in Example 1 were obtained using a BET analyzer (Micromeritics, ASAP-2020), and are shown below. Figure 3 and Figure 4 As shown.

[0151] from Figure 3 As can be seen from the figure, after the heat treatment in Example 1, the type II isotherm curve changed to the type IV isotherm curve, which means that the number of mesopores rather than the number of micropores increased.

[0152] In addition, from Figure 4 As can be seen from the figure, the surface area and volume of the central hole are greatly increased through the heat treatment of Example 1.

[0153] [Transmission electron microscopy (TEM) analysis of the catalyst]

[0154] Figure 5 (a) and (b) are transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HR-TEM) images of the catalyst obtained by dispersing catalyst metal particles on the activated acetylene black support of Example 1. Figure 5 As can be seen from the images, the catalyst metal particles are uniformly distributed on the solid carbon support of this invention.

Claims

1. A carbon-based support, said carbon support being used as a fuel cell catalyst, wherein, The carbon-based support is a solid support and has a density of 100m. 2 / g to 450m 2 / g external surface area, 150m 2 / g to 600m 2 / g BET surface area, 0.25cm 3 / g to 0.65cm 3 / g of mesopore volume and 0.01cm 3 / g to 0.05cm 3 / g micropore volume, Each of the external surface area, the BET surface area, the mesopore volume, and the micropore volume is the arithmetic mean of measurements obtained from five randomly selected samples using a micrometer-scale Bruno Emmett Teller analyzer (ASAP-2020), i.e., a BET analyzer.

2. The carbon-based support according to claim 1, wherein, The carbon support has to The d-spacing value was calculated using Bragg's law based on the (002) peak obtained through XRD analysis.

3. The carbon-based support according to claim 1, wherein, The carbon-based carrier is an acetylene black carrier.

4. A catalyst, comprising: The carbon-based support according to claim 1; as well as Catalyst metal particles, which are dispersed on the carbon-based support.

5. A membrane-electrode assembly, comprising: anode; cathode; as well as A polymer electrolyte membrane is disposed between the anode and the cathode; Wherein, at least one of the anode and the cathode comprises the catalyst according to claim 4.

6. A method for manufacturing a carbon-based support, the method comprising: Raw material carriers for preparing solid carbon; as well as The raw material carrier is heat-treated so that the carrier activated by the heat treatment satisfies the following equations 1 to 4: [Formula 1] S EX_AS ≥S EX_RS ×3 [Equation 2] In MESO_AS ≥V MESO_RS ×1.2 [Formula 3] In MICRO_AS ≤V MICRO_RS ×1.1 [Formula 4] S BET_AS ≥S BET_RS ×2 Among them, S EX_AS It is the outer surface area of ​​the activation carrier and is within 100m². 2 / g to 450m 2 Within the range of / g, S EX_RS S is the outer surface area of ​​the raw material carrier. BET_AS The BET surface area of ​​the activated carrier is 150m². 2 / g to 600m 2 Within the range of / g, S BET_RS V is the BET surface area of ​​the raw material carrier. MESO_AS The mesopore volume of the activated carrier is 0.25 cm. 3 / g to 0.65cm 3 Within the range of / g, V MESO_RS V is the volume of the mesopores in the raw material carrier. MICRO_AS The micropore volume of the activated carrier is 0.01 cm. 3 / g to 0.05cm 3 Within the range of / g, and V MICRO_RS It is the micropore volume of the raw material carrier, and Each of the external surface area, the BET surface area, the mesopore volume, and the micropore volume is the arithmetic mean of measurements obtained from five randomly selected samples using a micrometer-scale ASAP-2020 BET analyzer.

7. The method according to claim 6, wherein, To enable the activated carrier to undergo the heat treatment in a manner that further satisfies Equations 5 and 6 below: [Formula 5] DS AS ≤DS RS ×1.1 [Formula 6] I AS ≥I RS ×0.5 Among them, DS AS The d-interval value is calculated using Bragg's law based on the (002) peak obtained through XRD analysis of the activated support. RS The d-interval value is calculated using Bragg's law based on the (002) peak obtained from XRD analysis of the raw material carrier. AS The intensity of the (002) peak was obtained through XRD analysis of the activated support, and I RS The intensity of the (002) peak is obtained through XRD analysis of the raw material carrier.

8. The method of claim 6, further comprising: Thermogravimetric analysis of the raw material carrier was performed prior to the heat treatment. as well as Based on the results of the thermogravimetric analysis, the first temperature at which a 20% weight loss occurs was determined. The heat treatment is carried out in air at a second temperature satisfying Equation 7 below: [Formula 7] T1–40℃≤T2≤T1+40℃ Wherein, T1 is the first temperature and T2 is the second temperature.

9. The method according to claim 8, wherein, The heat treatment is carried out for 0.5 to 8 hours.

10. The method according to claim 6, wherein, The raw material carrier includes acetylene black.

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