Platinum composite catalyst and preparation method thereof, membrane electrode assembly and fuel cell

Abstract

The invention relates to a platinum composite catalyst and a preparation method thereof, a membrane electrode assembly and a fuel cell. The preparation method of the platinum composite catalyst comprises the following steps: providing a graphene-based platinum catalyst, wherein the graphene-based platinum catalyst comprises a graphene carrier and first platinum particles loaded on the surface of the graphene carrier; an organic compound which is in a liquid state at normal temperature is used as a carbon source, the organic compound is placed in a first tubular furnace, a graphene-based platinum catalyst is placed in a second tubular furnace, the first tubular furnace and the second tubular furnace are connected through a quartz tube, and under the vacuum condition, the first tubular furnace and the second tubular furnace are heated respectively to obtain a graphene-based platinum catalyst; depositing a graphene layer on the surface of a first platinum particle in the graphene-based platinum catalyst to prepare a platinum catalyst coated with the graphene layer; a platinum source is used as a raw material, and second platinum particles are loaded on the surface of a graphene layer in the platinum catalyst coated with the graphene layer and in pores of a graphene carrier by adopting a sol-gel method. The prepared platinum composite catalyst has high catalytic activity.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a platinum composite catalyst and a preparation method thereof, a membrane electrode assembly and a fuel cell. Background Art

[0002] Fuel cells, especially proton exchange membrane fuel cells (PEMFCs), are considered an important part of future sustainable energy technology due to their high energy density, high efficiency and environmental friendliness. Platinum (Pt) catalysts play a vital role in fuel cells. They are mainly used to catalyze the oxygen reduction reaction (ORR) at the cathode, which is the rate-limiting step in the energy conversion process of fuel cells. The performance of platinum catalysts directly affects the overall efficiency, cost and durability of fuel cells. However, the catalytic performance of platinum catalysts used in traditional fuel cells is poor.

[0003] Therefore, it is necessary to improve the traditional technology. Summary of the invention

[0004] Based on this, the present application provides a platinum composite catalyst with good catalytic performance and a preparation method thereof, a membrane electrode assembly and a fuel cell.

[0005] The technical solution of this application to solve the above technical problems is as follows.

[0006] On the one hand, the present application provides a method for preparing a platinum composite catalyst, comprising the following steps:

[0007] Providing a graphene-based platinum catalyst, wherein the graphene-based platinum catalyst comprises a graphene carrier and first platinum particles supported on the surface of the graphene carrier;

[0008] An organic compound that is liquid at room temperature is used as a carbon source, the organic compound is placed in a first tubular furnace, the graphene-based platinum catalyst is placed in a second tubular furnace, the first tubular furnace and the second tubular furnace are connected by a quartz tube, and the first tubular furnace and the second tubular furnace are heated separately under vacuum conditions to deposit a graphene layer on the surface of the first platinum particles in the graphene-based platinum catalyst to prepare a graphene layer-coated platinum catalyst;

[0009] Using a platinum source as a raw material and adopting a sol-gel method, second platinum particles are loaded on the surface of the graphene layer in the platinum catalyst coated with the graphene layer and in the pores of the graphene carrier.

[0010] In some of the embodiments, in the method for preparing the platinum composite catalyst, the organic compound includes at least one of an alcohol having 1 to 6 carbon atoms and a nitrile having 1 to 4 carbon atoms.

[0011] In some of the embodiments, in the method for preparing the platinum composite catalyst, the organic compound includes at least one of methanol, ethanol and acetonitrile.

[0012] In some of the embodiments, in the method for preparing the platinum composite catalyst, the mass ratio of the volume of the organic compound to the graphene-based platinum catalyst is 10 mL~100 mL:1 g.

[0013] In some of the embodiments, in the method for preparing a platinum composite catalyst, the temperature of the second tubular furnace is greater than the temperature of the first tubular furnace.

[0014] In some of the embodiments, in the method for preparing the platinum composite catalyst, the temperature of the first tube furnace is 80°C to 150°C, and the temperature of the second tube furnace is 200°C to 500°C.

[0015] In some of the embodiments, in the method for preparing the platinum composite catalyst, the heating time is 0.1 h to 10 h.

[0016] In some embodiments, in the method for preparing the platinum composite catalyst, loading the second platinum particles comprises the following steps:

[0017] The platinum catalyst coated with the graphene layer, a platinum source and a solvent are mixed and reacted at 80° C. to 200° C. for 0.5 h to 14 h.

[0018] In some of the embodiments, in the method for preparing the platinum composite catalyst, the platinum source includes at least one of chloroplatinic acid, ammonium hexachloroplatinate, platinum acetylacetonate, potassium chloroplatinate, platinum acetylacetonate and ammonium tetrachloroplatinate.

[0019] On one hand, the present application provides a platinum composite catalyst, which is prepared by the above-mentioned preparation method of the platinum composite catalyst.

[0020] In some embodiments, in the platinum composite catalyst, the total mass content of platinum particles in the platinum composite catalyst is 40% to 70%; and / or,

[0021] The average particle size of the platinum particles is 5 nm to 20 nm.

[0022] On the one hand, the present application provides a membrane electrode assembly, including a proton exchange membrane, a catalyst layer and a gas diffusion layer, wherein the catalyst layer is arranged on at least one side of the proton exchange membrane, and the gas diffusion layer is arranged on a side of the catalyst layer away from the proton exchange membrane, and the catalyst layer includes the above-mentioned platinum composite catalyst.

[0023] On one hand, the present application provides a fuel cell, comprising an anode plate, a cathode plate and the above-mentioned membrane electrode assembly, wherein the anode plate and the cathode plate are arranged on both sides of the membrane electrode assembly.

[0024] Compared with the prior art, the preparation method of the platinum composite catalyst of the present application has the following beneficial effects:

[0025] The preparation method of the platinum composite catalyst of the present application uses an organic compound that is liquid at room temperature as a carbon source, places the organic compound in a first tubular furnace, places a graphene-based platinum catalyst in a second tubular furnace, and connects the first tubular furnace and the second tubular furnace through a quartz tube. Under vacuum conditions, the first tubular furnace and the second tubular furnace are heated separately, and the graphene-based platinum catalyst is subjected to chemical vapor deposition to deposit a graphene layer on the surface of a first platinum particle in the graphene-based platinum catalyst; wherein the liquid carbon source in the first tubular furnace generates steam during the heating process, and the pores of the graphene carrier in the graphene-based platinum catalyst are expanded, which effectively promotes the subsequent use of a sol-gel method to load platinum particles on the surface of the graphene layer in the platinum catalyst coated with the graphene layer and in the pores of the graphene carrier, thereby increasing the effective area of ​​the platinum particles, thereby effectively improving the catalytic activity and stability of the platinum composite catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application and to more completely understand the present application and its beneficial effects, the following is a brief introduction to the drawings required for the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0027] Figure 1 The microscopic morphology of the graphene-platinum composite catalyst prepared in Example 1;

[0028] Figure 2 The linear voltammetric scans of the catalysts prepared in Example 1 and Comparative Example 1;

[0029] Figure 3 The current density of the catalysts prepared in Example 1 and Comparative Example 1 before and after 30,000 cycles;

[0030] Figure 4 The linear voltammetric scan diagrams of the catalysts prepared in Example 1 and Example 2 are shown. DETAILED DESCRIPTION

[0031] The present application will be further described in detail below in conjunction with the accompanying drawings, implementation modes and examples. It should be understood that these implementation modes and examples are only used to illustrate the present application and are not used to limit the scope of the present application. The purpose of providing these implementation modes and examples is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0032] It should also be understood that the present application can be implemented in many different forms and is not limited to the embodiments and examples described herein. Those skilled in the art can make various changes or modifications without violating the connotation of the present application, and the equivalent forms obtained also fall within the scope of protection of the present application. For example, the features illustrated or described as part of one embodiment can be combined in another embodiment in a suitable manner to produce a new embodiment. In addition, in the description below, a large number of specific details are given in order to provide a more comprehensive understanding of the present application. It should be understood that the present application can be implemented without one or more of these details.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing implementation modes and embodiments and are not intended to limit this application.

[0034] Unless otherwise specified or incompatible herewith, the terms and phrases used herein shall have the following meanings:

[0035] In the present application, "plurality", "multiple", "multiple times", etc., unless otherwise specified, refer to a number greater than 2 or equal to 2. For example, "one or more" means one or greater than or equal to two.

[0036] As used herein, "combination thereof", "any combination thereof", "any combination thereof" etc. include all suitable combinations of any two or more of the listed items.

[0037] Herein, the “suitable” mentioned in “suitable combination”, “suitable method”, “any suitable method”, etc., shall be based on the ability to implement the technical solution of this application, solve the technical problems of this application, and achieve the expected technical effects of this application.

[0038] Herein, "preferred", "better", "more preferred", and "suitable" are only used to describe implementation methods or examples with better effects, and it should be understood that they do not constitute a limitation on the scope of protection of this application. If multiple "preferred" items appear in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "preferred" item is independent.

[0039] In the present application, "further", "further", "particularly" and the like are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of the present application.

[0040] In this application, "optionally", "optional", and "optional" mean optional or dispensable, that is, any one of the two parallel schemes of "yes" or "no". If multiple "options" appear in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "optional" is independent.

[0041] In the present application, the terms "first", "second", "third", "fourth", etc. in "the first aspect", "the second aspect", "the third aspect", "the fourth aspect", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", "third", "fourth", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0042] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0043] In the present application, when it comes to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​in the numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e., the minimum value and the maximum value) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to the integers in the numerical interval, it includes the two endpoint integers of the numerical range, and each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical range disclosed herein should be understood to include any and all sub-ranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows broadly including numerical interval types such as percentage intervals, ratio intervals, and ratio intervals.

[0044] The temperature parameters in this application, unless otherwise specified, are allowed to be either constant temperature treatment or to vary within a certain temperature range. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within the range of ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are allowed.

[0045] In this application, the term "room temperature" or "normal temperature" generally refers to 4°C to 35°C, for example, 20°C ± 5°C. In some embodiments of this application, "room temperature" or "normal temperature" refers to 10°C to 30°C. In some embodiments of this application, "room temperature" or "normal temperature" refers to 20°C to 30°C.

[0046] In this application, when referring to the unit of a data range, if there is a unit only after the right endpoint, it means that the units of the left and right endpoints are the same. For example, 3~5 h means that the units of the left endpoint "3" and the right endpoint "5" are both h (hours).

[0047] All documents mentioned in this application are cited as references in this application, just as each document is cited as reference separately. Unless they conflict with the invention purpose and / or technical solution of this application, the cited documents involved in this application are cited with all contents and all purposes. When the cited documents are involved in this application, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also cited. When the cited documents are involved in this application, the examples and preferred methods of the cited relevant technical features can also be incorporated into this application as references, but are limited to the implementation of this application. It should be understood that when the cited content conflicts with the description in this application, the present application shall prevail or be modified adaptively according to the description of this application.

[0048] The mass or weight of the relevant components mentioned in the specification of the embodiments of the present application may not only refer to the specific content of each component, but also indicate the proportional relationship of the mass or weight between the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the specification of the embodiments of the present application, it is within the scope disclosed in the specification of the embodiments of the present application. Specifically, the mass or weight described in the specification of the embodiments of the present application may be units known in the chemical industry such as μg, mg, g, and kg.

[0049] As described in the background technology, the catalytic performance of platinum catalysts used in traditional fuel cells is poor. After research and analysis, the reasons for the poor catalytic performance and stability of traditional platinum catalysts are as follows:

[0050] 1. Platinum catalysts may form surface oxides in the working environment. These oxides will change the electronic structure and activity of the catalyst, causing the catalyst to be deactivated, thereby reducing the stability and catalytic activity of the catalyst.

[0051] 2. The disordered distribution of the active component platinum leads to uneven distribution of active sites. During the operation of the fuel cell, the interaction between platinum and the carrier is weakened, causing the shedding, migration and agglomeration of platinum nanoparticles, which in turn leads to battery performance degradation.

[0052] An embodiment of the present application provides a method for preparing a platinum composite catalyst, comprising the following steps:

[0053] Step S10: providing a graphene-based platinum catalyst, the graphene-based platinum catalyst comprising a graphene carrier and a first platinum particle supported on the surface of the graphene carrier; taking an organic compound that is liquid at room temperature as a carbon source, placing the organic compound in a first tubular furnace, placing the graphene-based platinum catalyst in a second tubular furnace, the first tubular furnace and the second tubular furnace being connected by a quartz tube, and heating the first tubular furnace and the second tubular furnace respectively under vacuum conditions to deposit a graphene layer on the surface of the first platinum particle in the graphene-based platinum catalyst to prepare a graphene layer-coated platinum catalyst.

[0054] It can be understood that the graphene-based platinum catalyst includes a graphene carrier and a first platinum particle supported on the surface of the graphene carrier, and the graphene layer-coated platinum catalyst obtained in step S10 includes a graphene-based platinum catalyst and a graphene layer disposed on the surface of the first platinum particle in the graphene-based platinum catalyst. It can be further understood that the graphene layer is a discontinuous film layer.

[0055] An organic compound that is liquid at room temperature is used as a carbon source, the organic compound is placed in a first tubular furnace, a graphene-based platinum catalyst is placed in a second tubular furnace, the first tubular furnace and the second tubular furnace are connected via a quartz tube, the first tubular furnace and the second tubular furnace are heated respectively under vacuum conditions, and chemical vapor deposition is performed on the graphene-based platinum catalyst to deposit a graphene layer on the surface of a first platinum particle in the graphene-based platinum catalyst; wherein the liquid carbon source in the first tubular furnace generates steam during the heating process, and the pores of the graphene carrier in the graphene-based platinum catalyst are expanded.

[0056] It can be understood that normal temperature refers to the temperature range under atmospheric pressure without any external conditions. Further, normal temperature can include a range of 10°C to 35°C.

[0057] In some examples, in step S10, the organic compound includes at least one of an alcohol having 1 to 6 carbon atoms and a nitrile having 1 to 4 carbon atoms.

[0058] It can be understood that alcohols with carbon atoms of 1 to 6 include methanol, ethanol, propanol (including n-propanol and isopropanol), butanol (including n-butanol, isobutanol, sec-butanol, tert-butanol), pentanol (including but not limited to n-pentanol, isopentanol, etc.) and hexanol (including but not limited to n-hexanol, etc.).

[0059] It can be understood that alcohols with carbon atoms of 1 to 6 will decompose into water vapor at high temperatures, and nitriles with carbon atoms of 1 to 4 will decompose into ammonia at high temperatures. Both water vapor and ammonia can have a pore-expanding effect on graphene.

[0060] In some examples, in step S10, the organic compound includes at least one of methanol, ethanol, and acetonitrile.

[0061] In some of the examples, in step S10, the volume ratio of the organic compound to the mass ratio of the graphene-based platinum catalyst is 10 mL~100 mL:1 g.

[0062] It can be understood that the volume ratio of the organic compound to the mass ratio of the graphene-based platinum catalyst is 10 mL~100 mL:1 g, which means that 10 mL~100 mL of organic compound is used for every 1 g of graphene-based platinum catalyst; further, the volume ratio of the organic compound to the mass ratio of the graphene-based platinum catalyst includes but is not limited to 10 mL, 20 mL, 30 mL, 40 mL, 50 mL, 60 mL, 70 mL, 80 mL, 90 mL, 100 mL:1 g; in some examples, it can be within the range consisting of any two of these point values ​​as end values, the same below.

[0063] In some of the examples, in step S10 , the temperature of the second tube furnace is greater than the temperature of the first tube furnace.

[0064] In some of the examples, in step S10, the temperature of the first tube furnace is 80°C to 150°C, and the temperature of the second tube furnace is 200°C to 500°C.

[0065] It can be understood that the temperature of the first tube furnace includes but is not limited to 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, and 150℃, and the temperature of the second tube furnace includes but is not limited to 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, 410℃, 420℃, 430℃, 440℃, 450℃, 460℃, 470℃, 480℃, 490℃, and 500℃.

[0066] In some of the examples, in step S10, the heating time is 0.1 h to 10 h.

[0067] It will be appreciated that the heating time includes, but is not limited to, 0.1 h, 0.5 h, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, and 10 h.

[0068] In some examples, in step S10, the preparation of the graphene-based platinum catalyst includes step S11:

[0069] With graphene as a carrier and a platinum source as a raw material, a sol-gel method is adopted to load first platinum particles on the surface of the graphene carrier.

[0070] In some examples, step S11 includes:

[0071] Mix graphene, platinum source and solvent and react at 80℃~200℃ for 0.5 h~14 h.

[0072] It can be understood that in step S11, the reaction temperature includes but is not limited to 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, and 200°C; the reaction time includes but is not limited to 0.5 h, 1 h, 2 h, 3 h, 5 h, 6 h, 7 h, 8 h, 10 h, 12 h, and 14 h.

[0073] In some examples, step S11 is performed under an inert atmosphere.

[0074] It can be understood that the inert atmosphere includes but is not limited to at least one of nitrogen and argon.

[0075] It can be understood that in step S11, the platinum source and the solvent can be mixed first to prepare a platinum source solution, and then the graphene is mixed with the platinum source solution.

[0076] It can be understood that in step S11, the graphene, platinum source and solvent are mixed and then ultrasonically dispersed uniformly.

[0077] Step 20: Using a platinum source as a raw material, and adopting a sol-gel method, second platinum particles are loaded on the surface of the graphene layer in the platinum catalyst coated with a graphene layer and in the pores of the graphene carrier.

[0078] An organic compound that is liquid at room temperature is used as a carbon source, the organic compound is placed in a first tubular furnace, a graphene-based platinum catalyst is placed in a second tubular furnace, the first tubular furnace and the second tubular furnace are connected by a quartz tube, the first tubular furnace and the second tubular furnace are heated respectively under vacuum conditions, and the graphene-based platinum catalyst is subjected to chemical vapor deposition to deposit a graphene layer on the surface of a first platinum particle in the graphene-based platinum catalyst; wherein the liquid carbon source in the first tubular furnace generates steam during the heating process, and the pores of the graphene carrier in the graphene-based platinum catalyst are expanded, which effectively promotes the subsequent use of a sol-gel method to load platinum particles on the surface of the graphene layer in the platinum catalyst coated with the graphene layer and in the pores of the graphene carrier, thereby increasing the effective area of ​​the platinum particles, thereby effectively improving the catalytic activity and stability of the platinum composite catalyst.

[0079] It can be understood that the region where the second platinum particles are loaded includes the surface of the graphene layer and the pores of the graphene carrier.

[0080] In the preparation method of the platinum composite catalyst of the present application, the second platinum particles can be uniformly loaded on the surface of the graphene layer in the platinum catalyst coated with the graphene layer and in the pores of the graphene carrier without agglomeration.

[0081] The preparation method of the platinum composite catalyst of the present application combines graphene and platinum particles layer by layer, effectively improving the catalytic activity and utilization rate of the platinum composite catalyst.

[0082] It can be understood that the platinum composite catalyst prepared in step S20 includes a graphene-based platinum catalyst, a graphene layer disposed on the surface of a first platinum particle in the graphene-based platinum catalyst, and a second platinum particle supported on the surface of the graphene layer and in the pores of the graphene carrier. The graphene-based platinum catalyst includes a graphene carrier and a first platinum particle supported on the surface of the graphene carrier, and the graphene layer is coated on the surface of the first platinum particle in the graphene-based platinum catalyst.

[0083] It can be further understood that the platinum composite catalyst prepared in step S20 includes a platinum-graphene-platinum-graphene structure from the outside to the inside.

[0084] In some examples, in step S20, loading the second platinum particles includes the following steps:

[0085] The platinum catalyst coated with the graphene layer, the platinum source and the solvent are mixed and reacted at 80°C to 200°C for 0.5 h to 14 h.

[0086] It can be understood that in the step of loading the second platinum particles, the reaction temperature includes but is not limited to 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, and 200°C; the reaction time includes but is not limited to 0.5 h, 1 h, 2 h, 3 h, 5 h, 6 h, 7 h, 8 h, 10 h, 12 h, and 14 h.

[0087] In some examples, step S20 is performed under an inert atmosphere.

[0088] It can be understood that the inert atmosphere includes but is not limited to at least one of nitrogen and argon.

[0089] In some of the examples, in step S20, the platinum source includes at least one of chloroplatinic acid, ammonium hexachloroplatinate, platinum acetylacetonate, potassium chloroplatinate, platinum acetylacetonate, and ammonium tetrachloroplatinate.

[0090] It can be understood that in step S20, the platinum source and the solvent can be mixed first to prepare a platinum source solution, and then the platinum catalyst coated with the graphene layer is mixed with the platinum source solution.

[0091] It can be understood that in step S20, the platinum catalyst coated with the graphene layer, the platinum source and the solvent are mixed and then ultrasonically dispersed uniformly.

[0092] It can be understood that after step S20 is completed, step S10 and step S20 can be continued in a cycle to deposit a graphene layer on the surface of the composite material prepared in the previous step and load platinum particles on the surface of the graphene layer prepared in the previous step.

[0093] For example, in some examples, after step S20 is completed, the following steps are further included:

[0094] Step S30: Using an organic compound that is liquid at room temperature as a carbon source, placing the organic compound in a first tubular furnace, placing the composite material prepared in step S20 in a second tubular furnace, connecting the first tubular furnace and the second tubular furnace through a quartz tube, and heating the first tubular furnace and the second tubular furnace respectively under vacuum conditions to deposit a second graphene layer on the surface of the second platinum particles in the composite material prepared in step S20, preparing a graphene layer-coated platinum catalyst, and preparing a second graphene layer-coated platinum catalyst.

[0095] In some examples, after step S30 is completed, the following steps are further included:

[0096] Step S40: using a platinum source as a raw material and adopting a sol-gel method, loading third platinum particles on the surface of the second graphene layer in the platinum catalyst coated with the second graphene layer.

[0097] It can be understood that the platinum composite catalyst prepared in step S40 includes a platinum-graphene-platinum-graphene-platinum-graphene structure from the outside to the inside.

[0098] It can be understood that the catalytic performance of the finally prepared platinum composite catalyst is better when the outermost layer is platinum particles than when the outermost layer is a graphene layer; the more deposited layers there are, the higher the platinum content of the platinum composite catalyst and the higher the catalytic activity; however, if the particle size of the platinum composite catalyst is too large, it will also affect the catalytic activity of the catalyst, so it is more appropriate to deposit 1 to 10 graphene layers.

[0099] The preparation method of the platinum composite catalyst of the present application can effectively increase the loading amount of platinum particles, thereby effectively improving the catalytic activity of the platinum composite catalyst; through layer-by-layer coating loading, the stability performance of the platinum composite catalyst can be effectively improved.

[0100] One embodiment of the present application provides a platinum composite catalyst, which is prepared by the above-mentioned preparation method of the platinum composite catalyst.

[0101] It can be understood that in some of the examples, the platinum composite catalyst includes a graphene-based platinum catalyst, a graphene layer provided on the surface of a first platinum particle in the graphene-based platinum catalyst, and a second platinum particle loaded on the surface of the graphene layer and in the pores of the graphene carrier; wherein the graphene-based platinum catalyst includes a graphene carrier and a first platinum particle loaded on the surface of the graphene carrier, and the graphene layer is coated on the surface of the first platinum particle in the graphene-based platinum catalyst.

[0102] In some of the examples, in the platinum composite catalyst, the total mass content of the platinum particles in the platinum composite catalyst is 40%~70%.

[0103] It can be understood that the total mass content of platinum particles in the platinum composite catalyst refers to the percentage of the total mass of the platinum particles in the platinum composite catalyst to the total mass of the platinum composite catalyst; it can be further understood that the platinum composite catalyst includes at least the first platinum particles and the second platinum particles, that is, the total mass of the platinum particles in the platinum composite catalyst includes at least the total mass of the first platinum particles and the second platinum particles; further, the total mass content of the platinum particles in the platinum composite catalyst includes but is not limited to 40%, 42%, 45%, 48%, 50%, 52%, 55%, 58%, 60%, 62%, 65%, 68%, and 70%.

[0104] In some of these examples, the average particle size of platinum particles in the platinum composite catalyst is 5 nm~20 nm.

[0105] It can be understood that the platinum composite catalyst includes at least a first platinum particle and a second platinum particle, and the first platinum particle and the second platinum particle independently satisfy the above-mentioned particle size range; it can be further understood that the average particle size of the platinum particles includes but is not limited to 5 nm, 6 nm, 8 nm, 10 nm, 12 nm, 14 nm, 15 nm, 18 nm, and 20 nm.

[0106] The platinum composite catalyst provided in the present application has high catalytic activity and good stability.

[0107] One embodiment of the present application provides a membrane electrode assembly, including a proton exchange membrane, a catalyst layer and a gas diffusion layer, wherein the catalyst layer is arranged on at least one side of the proton exchange membrane, and the gas diffusion layer is arranged on a side of the catalyst layer away from the proton exchange membrane, and the catalyst layer includes the above-mentioned platinum composite catalyst.

[0108] The membrane electrode assembly provided in the present application, because it includes the above-mentioned platinum composite catalyst, can give the membrane electrode assembly higher catalytic activity and stability performance.

[0109] An embodiment of the present application provides a fuel cell, comprising an anode plate, a cathode plate and the above-mentioned membrane electrode assembly, wherein the anode plate and the cathode plate are arranged on both sides of the membrane electrode assembly.

[0110] The fuel cell provided in the present application, because it includes the above-mentioned membrane electrode assembly, can give the fuel cell higher catalytic activity and stability performance.

[0111] The present application is further described in detail below in conjunction with specific implementation methods, but the implementation methods of the present application are not limited thereto.

[0112] Example 1

[0113] (1) Add 0.5 g of graphene to 0.5 mg / mL chloroplatinic acid ethylene glycol solution and ultrasonicate for 1 h to make it uniformly dispersed to prepare a mixed solution;

[0114] (2) The mixed solution prepared in step (1) was transferred to an oil bath, nitrogen was introduced, and the mixture was heated to 120°C and kept warm for 45 min. After the reaction was completed, the reaction solution was centrifuged, and the solid product was placed in a drying oven and dried at 75°C for 24 h to obtain a graphene-based platinum catalyst (Pt / Gr).

[0115] (3) Using a quartz tube, connect tubular furnace A and tubular furnace B, check the airtightness, then put 100 mL of anhydrous ethanol in tubular furnace A, and put 0.1 g of Pt / Gr prepared in step (2) in tubular furnace B; evacuate the tubular furnace to a vacuum state, seal the tubular furnace, heat tubular furnace A to 90°C, heat tubular furnace B to 500°C, and keep them warm for 30 min to deposit a graphene layer on the surface of the Pt / Gr prepared in step (2), thereby obtaining a graphene-coated platinum catalyst C@Pt / Gr (including a graphene-platinum-graphene structure from the outside to the inside);

[0116] (4) The C@Pt / Gr prepared in step (3) was added to a 0.5 mg / mL chloroplatinic acid ethylene glycol solution, and after ultrasonic treatment for 1 h, nitrogen was introduced, and the mixture was heated to 120°C and kept warm for 45 min. After the reaction was completed, the reaction solution was centrifuged, and the solid product was placed in a drying oven and dried at 75°C for 24 h to obtain a graphene-platinum composite catalyst with a platinum-graphene-platinum-graphene structure from the outside to the inside.

[0117] The microscopic morphology of the graphene-platinum composite catalyst prepared in step (4) of Example 1 is as follows: Figure 1 shown.

[0118] Example 2

[0119] The process is basically the same as Example 1, except that in step (3), the volume of anhydrous ethanol placed in the tubular furnace A is 20 mL.

[0120] Example 3

[0121] The process is basically the same as Example 1, except that in step (3), 100 mL of acetonitrile is placed in the tubular furnace A.

[0122] Example 4

[0123] The process is basically the same as Example 1, except that in step (3), the temperature of tubular furnace A is raised to 150°C, and the temperature of tubular furnace B is raised to 300°C, and the temperatures are kept constant for 30 min.

[0124] Example 5

[0125] The method is basically the same as Example 1, except that the graphene-platinum composite catalyst having a platinum-graphene-platinum-graphene structure from the outside to the inside obtained in step (4) of Example 1 is subjected to steps (3) and (4) repeatedly.

[0126] Comparative Example 1

[0127] Commercial platinum-carbon catalyst (Kawamori Catalyst).

[0128] Comparative Example 2

[0129] (1) Add 0.5 g of graphene to 0.5 mg / mL chloroplatinic acid ethylene glycol solution and ultrasonicate for 1 h to make it uniformly dispersed to prepare a mixed solution;

[0130] (2) The mixed solution prepared in step (1) was transferred to an oil bath, nitrogen was introduced, and the mixture was heated to 120°C and kept warm for 45 min. After the reaction was completed, the reaction solution was centrifuged, and the solid product was placed in a drying oven and dried at 75°C for 24 h to obtain a graphene-based platinum catalyst (Pt / Gr).

[0131] (3) placing 100 mL of anhydrous ethanol and 0.1 g of the Pt / Gr prepared in step (2) in a tube furnace; evacuating the tube furnace to a vacuum state, sealing the tube furnace, heating the tube furnace to 150° C., and keeping the temperature for 30 min to deposit a graphene layer on the surface of the Pt / Gr prepared in step (2) to obtain a graphene-coated platinum catalyst C@Pt / Gr (comprising a graphene-platinum-graphene structure from the outside to the inside);

[0132] (4) The C@Pt / Gr prepared in step (3) was added to a 0.5 mg / mL chloroplatinic acid ethylene glycol solution, and after ultrasonic treatment for 1 h, nitrogen was introduced, and the mixture was heated to 120°C and kept warm for 45 min. After the reaction was completed, the reaction solution was centrifuged, and the solid product was placed in a drying oven and dried at 75°C for 24 h to obtain a graphene-platinum composite catalyst with a platinum-graphene-platinum-graphene structure from the outside to the inside.

[0133] Comparative Example 3

[0134] (1) Add 0.5 g of graphene to 0.5 mg / mL chloroplatinic acid ethylene glycol solution and ultrasonicate for 1 h to make it uniformly dispersed to prepare a mixed solution;

[0135] (2) The mixed solution prepared in step (1) was transferred to an oil bath, nitrogen was introduced, and the mixture was heated to 120°C and kept warm for 45 min. After the reaction was completed, the reaction solution was centrifuged, and the solid product was placed in a drying oven and dried at 75°C for 24 h to obtain a graphene-based platinum catalyst (Pt / Gr).

[0136] (3) placing 100 mL of anhydrous ethanol and 0.1 g of the Pt / Gr prepared in step (2) in a tube furnace; evacuating the tube furnace to a vacuum state, sealing the tube furnace, heating the tube furnace to 500° C., and keeping the temperature for 30 min to deposit a graphene layer on the surface of the Pt / Gr prepared in step (2) to obtain a graphene-coated platinum catalyst C@Pt / Gr (comprising a graphene-platinum-graphene structure from the outside to the inside);

[0137] (4) The C@Pt / Gr prepared in step (3) was added to a 0.5 mg / mL chloroplatinic acid ethylene glycol solution, and after ultrasonic treatment for 1 h, nitrogen was introduced, and the mixture was heated to 120°C and kept warm for 45 min. After the reaction was completed, the reaction solution was centrifuged, and the solid product was placed in a drying oven and dried at 75°C for 24 h to obtain a graphene-platinum composite catalyst with a platinum-graphene-platinum-graphene structure from the outside to the inside.

[0138] Comparative Example 4

[0139] (1) Add 0.5 g of graphene to 0.5 mg / mL chloroplatinic acid ethylene glycol solution and ultrasonicate for 1 h to make it uniformly dispersed to prepare a mixed solution;

[0140] (2) The mixed solution prepared in step (1) was transferred to an oil bath, nitrogen was introduced, and the mixture was heated to 120°C and kept warm for 45 min. After the reaction was completed, the reaction solution was centrifuged, and the solid product was placed in a drying oven and dried at 75°C for 24 h to obtain a graphene-based platinum catalyst (Pt / Gr).

[0141] (3) Using a quartz tube, connect tubular furnace A and tubular furnace B, check the airtightness, then put 100 mL of anhydrous ethanol in tubular furnace A and put 0.1 g of Pt / Gr prepared in step (2) in tubular furnace B; evacuate the tubular furnace to a vacuum state, seal the tubular furnace, heat tubular furnace A to 90°C, heat tubular furnace B to 500°C, and keep them warm for 30 min to deposit a graphene layer on the surface of the Pt / Gr prepared in step (2), thereby obtaining a graphene-coated platinum catalyst C@Pt / Gr (including a graphene-platinum-graphene structure from the outside to the inside).

[0142] Comparative Example 5

[0143] The method is basically the same as Example 3, except that in step (3), methane is used as the carbon source, as follows:

[0144] (1) Add 0.5 g of graphene to 0.5 mg / mL chloroplatinic acid ethylene glycol solution and ultrasonicate for 1 h to make it uniformly dispersed to prepare a mixed solution;

[0145] (2) The mixed solution prepared in step (1) was transferred to an oil bath, nitrogen was introduced, and the mixture was heated to 120°C and kept warm for 45 min. After the reaction was completed, the reaction solution was centrifuged, and the solid product was placed in a drying oven and dried at 75°C for 24 h to obtain a graphene-based platinum catalyst (Pt / Gr).

[0146] (3) Place 0.1 g of the Pt / Gr prepared in step (2) in a tube furnace, evacuate the tube furnace to a vacuum state, introduce methane gas at a rate of 60 mL / min, heat the tube furnace to 500 °C, and keep the temperature for 50 min to obtain C@Pt / Gr;

[0147] (4) The C@Pt / Gr prepared in step (3) was added to a 0.5 mg / mL chloroplatinic acid ethylene glycol solution, and after ultrasonic treatment for 1 h, nitrogen was introduced, and the mixture was heated to 120°C and kept warm for 45 min. After the reaction was completed, the reaction solution was centrifuged, and the solid product was placed in a drying oven and dried at 75°C for 24 h to obtain a graphene-platinum composite catalyst with a platinum-graphene-platinum-graphene structure from the outside to the inside.

[0148] Comparative Example 6

[0149] The process is basically the same as Comparative Example 3, except that in step (3), the temperature of the tubular furnace is raised to 900°C.

[0150] The catalyst-coated glassy carbon electrode prepared in each embodiment and comparative example was used as the working electrode, the platinum sheet electrode was used as the counter electrode, the saturated calomel electrode was used as the reference electrode, and 0.5 mol / L H2SO4 was used as the electrolyte to perform a linear voltammetric scan test.

[0151] Figure 2 The linear voltammetric scanning diagram of the catalysts prepared in Example 1 and Comparative Example 1 is shown in FIG. Figure 2 It can be seen that the half-wave potential of the platinum composite catalyst prepared in Example 1 is significantly better than that of the commercial platinum-carbon catalyst, and its catalytic performance is better. The half-wave potential refers to the voltage (x-axis) corresponding to the current density (y-axis) of the curve when it drops to half, and the larger the better.

[0152] The current density of the catalysts prepared in Example 1 and Comparative Example 1 before and after 30,000 cycles at 0.45 V is as follows: Figure 3 As shown. Figure 3 It can be seen that the current density loss rate of the platinum composite catalyst prepared in Example 1 is about 5.7%, and the current density loss rate of the commercial platinum-carbon catalyst is about 20.5%, indicating that the platinum composite catalyst prepared in Example 1 has better stability.

[0153] Figure 4 The linear voltammetric scan diagrams of the catalysts prepared in Example 1 and Example 2 are shown.

[0154] The total mass content of platinum in the catalysts prepared in various embodiments and comparative examples, the half-wave potential and the current density loss rate after 30,000 cycles are shown in Table 1.

[0155] Table 1

[0156]

[0157] It can be seen from Table 1 that, compared with the comparative example, the catalysts prepared in the embodiments have a higher platinum loading, a higher half-wave potential, a better catalytic activity, and a higher stability.

[0158] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0159] The above-described embodiments only express several implementation methods of the present application, which is convenient for understanding the technical solution of the present application in detail, but it cannot be understood as limiting the scope of protection of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several modifications and improvements can be made, which all belong to the scope of protection of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided in the present application are all within the scope of protection of the claims attached to the present application. Therefore, the scope of protection of the patent of this application shall be based on the contents of the attached claims, and the description and drawings can be used to explain the contents of the claims.

Claims

1. A method for preparing a platinum composite catalyst, characterized in that: The following steps are involved: Providing a graphene-based platinum catalyst, wherein the graphene-based platinum catalyst comprises a graphene carrier and first platinum particles supported on the surface of the graphene carrier; An organic compound that is liquid at room temperature is used as a carbon source, the organic compound is placed in a first tubular furnace, the graphene-based platinum catalyst is placed in a second tubular furnace, the first tubular furnace and the second tubular furnace are connected by a quartz tube, and the first tubular furnace and the second tubular furnace are heated separately under vacuum conditions to deposit a graphene layer on the surface of the first platinum particles in the graphene-based platinum catalyst to prepare a graphene layer-coated platinum catalyst; Using a platinum source as a raw material and adopting a sol-gel method, second platinum particles are loaded on the surface of the graphene layer in the platinum catalyst coated with the graphene layer and in the pores of the graphene carrier.

2. The preparation method according to claim 1, characterized in that The organic compound includes at least one of an alcohol having 1 to 6 carbon atoms and a nitrile having 1 to 4 carbon atoms.

3. The preparation method according to claim 2, characterized in that: The organic compound includes at least one of methanol, ethanol and acetonitrile.

4. The preparation method according to claim 1, characterized in that: The mass ratio of the volume of the organic compound to the graphene-based platinum catalyst is 10 mL~100 mL:1 g.

5. The preparation method according to any one of claims 1 to 4, characterized in that The temperature of the second tube furnace is greater than the temperature of the first tube furnace.

6. The preparation method according to claim 5, characterized in that: The temperature of the first tube furnace is 80°C to 150°C, and the temperature of the second tube furnace is 200°C to 500°C.

7. The preparation method according to claim 5, characterized in that: The heating time is 0.1 h to 10 h.

8. The preparation method according to any one of claims 1 to 4, 6 to 7, characterized in that: Loading the second platinum particles comprises the following steps: The platinum catalyst coated with the graphene layer, a platinum source and a solvent are mixed and reacted at 80° C. to 200° C. for 0.5 h to 14 h.

9. The preparation method according to any one of claims 1 to 4, 6 to 7, characterized in that: The platinum source includes at least one of chloroplatinic acid, ammonium hexachloroplatinate, platinum acetylacetonate, potassium chloroplatinate, platinum acetylacetonate and ammonium tetrachloroplatinate.

10. A platinum composite catalyst, characterized in that: The method is prepared according to any one of claims 1 to 9.

11. The platinum composite catalyst according to claim 10, characterized in that The total mass content of platinum particles in the platinum composite catalyst is 40% to 70%; and / or, The average particle size of the platinum particles is 5 nm to 20 nm.

12. A membrane electrode assembly, characterized in that: It comprises a proton exchange membrane, a catalyst layer and a gas diffusion layer, wherein the catalyst layer is arranged on at least one side of the proton exchange membrane, the gas diffusion layer is arranged on a side of the catalyst layer away from the proton exchange membrane, and the catalyst layer comprises the platinum composite catalyst as described in any one of claims 10 to 11.

13. A fuel cell, characterized in that: The invention comprises an anode plate, a cathode plate and a membrane electrode assembly as claimed in claim 12, wherein the anode plate and the cathode plate are arranged on both sides of the membrane electrode assembly.

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