Platinum composite catalyst, method for preparing the same, membrane electrode assembly and fuel cell

Abstract

The application relates to a platinum composite catalyst, 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; taking an organic compound in a liquid state at normal temperature as a carbon source; placing the organic compound in a first tube furnace and the graphene-based platinum catalyst in a second tube furnace; connecting the first tube furnace and the second tube furnace through a quartz tube; and heating the first tube furnace and the second tube furnace under vacuum conditions, so as to deposit a graphene layer on the surface of the first platinum particles in the graphene-based platinum catalyst and prepare a graphene layer coated platinum catalyst; and taking a platinum source as raw material and adopting a sol-gel method to load second platinum particles on the surface of the graphene layer and in the pores of the graphene carrier of the graphene layer coated platinum catalyst. The prepared platinum composite catalyst has high catalytic activity.

Description

TECHNICAL FIELD

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

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

[0003] Therefore, it is necessary to improve the traditional technology. SUMMARY

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

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

[0006] In one aspect, the present application provides a preparation method of a platinum composite catalyst, comprising the following steps:

[0007] A graphene-based platinum catalyst is provided, which includes a graphene carrier and first platinum particles loaded 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 tube furnace, and the graphene-based platinum catalyst is placed in a second tube furnace. The first tube furnace and the second tube furnace are connected by a quartz tube. The first tube furnace and the second tube 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, thereby preparing a platinum catalyst coated with a graphene layer.

[0009] A platinum source is used as a raw material, and a sol-gel method is used to load second platinum particles on the surface of the graphene layer and in the pores of the graphene carrier in the platinum catalyst coated with a graphene layer.

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

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

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

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

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

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

[0016] In some embodiments, the loading of the second platinum particles includes the following steps:

[0017] The graphene-coated platinum catalyst, the platinum source, and the solvent are mixed and reacted at 80℃-200℃ for 0.5 h-14 h.

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

[0019] In an aspect, the application provides a platinum composite catalyst prepared by the above method.

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

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

[0022] In an aspect, the application provides a membrane electrode assembly, which includes a proton exchange membrane, a catalyst layer, and a gas diffusion layer. The catalyst layer is arranged on at least one side of the proton exchange membrane, and the gas diffusion layer is arranged on the side of the catalyst layer away from the proton exchange membrane. The catalyst layer includes the above platinum composite catalyst.

[0023] In an aspect, the application provides a fuel cell, which includes an anode plate, a cathode plate, and the above membrane electrode assembly. 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 has the following beneficial effects:

[0025] The preparation method of the platinum composite catalyst of the present application uses an organic compound in a liquid state at room temperature as a carbon source, places the organic compound in a first tube furnace, places the graphene-based platinum catalyst in a second tube furnace, connects the first tube furnace and the second tube furnace through a quartz tube, and heats the first tube furnace and the second tube furnace under vacuum conditions, respectively, to perform chemical vapor deposition on the graphene-based platinum catalyst to deposit a graphene layer on the surface of the first platinum particles in the graphene-based platinum catalyst; wherein the liquid carbon source in the first tube furnace generates vapor during the heating process, which expands the pores of the graphene carrier in the graphene-based platinum catalyst, effectively promotes the subsequent loading of platinum particles on the surface of the graphene layer and in the pores of the graphene carrier in the graphene layer-coated platinum catalyst using the sol-gel method, increases the effective area of the platinum particles, and thus effectively improves the catalytic activity and stability of the platinum composite catalyst. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, more completely understand the present application and its beneficial effects, the drawings needed to be used in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0027] Figure 1 Micro-morphology diagram of the graphene-platinum composite catalyst prepared for Example 1;

[0028] Figure 2 Linear voltammetry scan diagram of the catalyst prepared for Example 1 and Comparative Example 1;

[0029] Figure 3 Current density situation diagram of the catalyst prepared for Example 1 and Comparative Example 1 before and after 30000 cycles;

[0030] Figure 4 Linear voltammetry scan diagram of the catalyst prepared for Example 1 and Example 2. DETAILED DESCRIPTION

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

[0032] It should also be understood that this 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 alterations or modifications without departing from the spirit of this application, and the resulting equivalent forms also fall within the protection scope of this application. For example, features described or illustrated as part of one embodiment can be combined in a suitable manner in another embodiment to produce new embodiments. Furthermore, numerous specific details are set forth in the following description to provide a fuller understanding of this application; it should be understood that this 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 commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for descriptive purposes only and is not intended to be limiting of the application.

[0034] Unless otherwise stated or in case of contradiction, the terms or phrases used herein shall have the following meanings:

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

[0036] The terms “combinations of,” “any combination of,” and “any combination of” used in this article include all suitable combinations of any two or more of the listed items.

[0037] In this document, the term "suitable" as used in "suitable combination", "suitable method", "any suitable method", etc., refers to the ability to implement the technical solution of this application, solve the technical problem of this application, and achieve the expected technical effect of this application.

[0038] In this document, terms such as "preferred," "better," "more suitable," and "ideal" are merely descriptions of more effective implementation methods or embodiments, and should be understood not to limit the scope of protection of this application. If multiple "preferred" terms appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "preferred" term shall be independent.

[0039] In this application, terms such as "further," "even further," and "particularly" are used to describe purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0040] In the present application, "optionally", "optional", "option" means optional, that is, selected from "yes" or "no" two parallel schemes. If there are multiple "options" in a technical solution, unless otherwise specified, and there is no contradiction or mutual restriction, each "option" is independent.

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

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

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

[0044] In the present application, unless otherwise specified, the temperature parameter allows for constant temperature treatment and allows for variation within a certain temperature interval. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. It is allowed to fluctuate within the range of, for example, ±5°C, ±4°C, ±3°C, ±2°C, ±1°C.

[0045] In the present 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 the present application, "room temperature" or "normal temperature" refers to 10°C to 30°C. In some embodiments of the present application, "room temperature" or "normal temperature" refers to 20°C to 30°C.

[0046] In the present application, if the unit is only behind the right end point, it means that the units of the left end point and the right end point are the same. For example, 3~5 h means that the units of the left end point "3" and the right end point "5" are both h (hours).

[0047] All the documents mentioned in the present application are cited as references in the present application as if each document is cited as a reference individually. Unless and to the extent that the cited documents conflict with the purpose and / or technical solutions of the present application, the cited documents are cited in the present application in their entirety, in their entirety purpose. When the present application refers to the cited documents, the definitions of the related technical features, terms, nouns, phrases, etc. in the cited documents are also cited. When the present application refers to the cited documents, the examples and preferred modes of the cited related technical features can also be incorporated into the present application as references, but are limited to the implementation of the present application. It should be understood that when the cited content conflicts with the description in the present application, the present application is used as the reference or is modified according to the description in the present application.

[0048] The mass or weight of the related components mentioned in the present application embodiment specification can not only refer to the specific content of each component, but also represent the mass or weight ratio relationship between each component. Therefore, as long as the content of the related components in the present application embodiment specification is enlarged or reduced in proportion, it is within the scope disclosed in the present application embodiment specification. Specifically, the mass or weight mentioned in the present application embodiment specification can be μg, mg, g, kg and other units well known in the chemical field.

[0049] As described in the background, the platinum catalyst used in the traditional fuel cell has poor catalytic performance. Through research and analysis, the reasons for the poor catalytic performance and stability of the traditional platinum catalyst are as follows:

[0050] 1. Platinum catalysts may form surface oxides in the working environment, which can change the electronic structure and activity of the catalyst, leading to catalyst deactivation, 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, and further leading to the performance degradation of the battery.

[0052] An embodiment of the present application provides a preparation method of 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 first platinum particles supported on a surface of the graphene carrier; taking an organic compound in a liquid state at room temperature as a carbon source, placing the organic compound in a first tube furnace, placing the graphene-based platinum catalyst in a second tube furnace, connecting the first tube furnace and the second tube furnace through a quartz tube, and heating the first tube furnace and the second tube furnace respectively under vacuum conditions to deposit a graphene layer on surfaces of the first platinum particles in the graphene-based platinum catalyst, thereby preparing a graphene layer-coated platinum catalyst.

[0054] It can be understood that the graphene-based platinum catalyst comprises a graphene carrier and first platinum particles supported on a surface of the graphene carrier, and the graphene layer-coated platinum catalyst prepared in step S10 comprises the graphene-based platinum catalyst and the graphene layer provided on the surfaces of the first platinum particles in the graphene-based platinum catalyst. It can be further understood that the graphene layer is a discontinuous film layer.

[0055] The organic compound in a liquid state at room temperature is taken as a carbon source, the organic compound is placed in a first tube furnace, the graphene-based platinum catalyst is placed in a second tube furnace, the first tube furnace and the second tube furnace are connected through a quartz tube, and the first tube furnace and the second tube furnace are heated respectively under vacuum conditions to perform chemical vapor deposition on the graphene-based platinum catalyst, so as to deposit a graphene layer on surfaces of the first platinum particles in the graphene-based platinum catalyst; wherein the liquid carbon source in the first tube furnace generates vapor during the heating process, and the graphene carrier in the graphene-based platinum catalyst is expanded.

[0056] It can be understood that room temperature refers to a temperature range in the absence of any external conditions.

[0057] In some examples, the organic compound in step S10 comprises at least one of an alcohol with a carbon atom number of 1-6 and a nitrile with a carbon atom number of 1-4.

[0058] It can be understood that the alcohol with a carbon atom number of 1-6 includes methanol, ethanol, propanol (including n-propanol and isopropanol), butanol (including n-butanol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol), 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 the alcohol with a carbon atom number of 1-6 will decompose water vapor at high temperature, and the nitrile with a carbon atom number of 1-4 will decompose ammonia gas at high temperature, both of which can expand the graphene.

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

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

[0062] It can be understood that the volume of the organic compound to the mass of the graphene-based platinum catalyst is 10 mL-100 mL: 1 g, which means that 10 mL-100 mL of the organic compound is used per 1 g of the graphene-based platinum catalyst; further, the volume of the organic compound to the mass 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 constituted by any two of these point values as end values, and the same applies below.

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

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

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

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

[0067] It can be understood 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, 10 h.

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

[0069] The first platinum particles are loaded on the surface of the graphene carrier by using a sol-gel method with graphene as the carrier and a platinum source as the raw material.

[0070] In some examples, step S11 includes:

[0071] mixing graphene, a platinum source and a solvent, and reacting at 80-200℃ for 0.5-14 hours.

[0072] It can be understood that the reaction temperature in step S11 includes but is not limited to 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, 200℃; 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, 14 h.

[0073] In some examples, the reaction in step S11 is carried out 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 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, the platinum source and the solvent are mixed and uniformly dispersed by ultrasonic.

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

[0078] An organic compound in a liquid state at room temperature is used as a carbon source. The organic compound is placed in a first tube furnace, and the graphene-based platinum catalyst is placed in a second tube furnace. The first tube furnace and the second tube furnace are connected by a quartz tube. The first tube furnace and the second tube furnace are heated separately under vacuum conditions. The graphene-based platinum catalyst is subjected to chemical vapor deposition to deposit a graphene layer on the surface of the first platinum particle in the graphene-based platinum catalyst. During the heating process, the liquid carbon source in the first tube furnace generates vapor, which expands the pores of the graphene carrier in the graphene-based platinum catalyst, effectively promotes the subsequent loading of platinum particles on the surface of the graphene layer and the pores of the graphene carrier in the graphene layer-coated platinum catalyst by a sol-gel method, and increases 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 particle is loaded includes the surface of the graphene layer and the pores of the graphene carrier.

[0080] The preparation method of the platinum composite catalyst of the present application can uniformly load the second platinum particle on the surface of the graphene layer and the pores of the graphene carrier in the graphene layer-coated platinum catalyst without agglomeration.

[0081] The method for preparing the platinum composite catalyst of the present application effectively improves the catalytic activity and utilization rate of the platinum composite catalyst by layer-by-layer combination of graphene and platinum particles.

[0082] It can be understood that the platinum composite catalyst prepared in step S20 includes a graphene-based platinum catalyst, a graphene layer arranged on the surface of the first platinum particles in the graphene-based platinum catalyst, and second platinum particles loaded 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 first platinum particles loaded on the surface of the graphene carrier, and the graphene layer is coated on the surface of the first platinum particles 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, the step of loading the second platinum particles includes the following steps:

[0085] The graphene layer-coated platinum catalyst, 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 the reaction temperature in the step of loading the second platinum particles 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, in step S20, the reaction is carried out 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 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 to prepare a platinum source solution, and then the graphene layer-coated platinum catalyst is mixed with the platinum source solution.

[0091] It can be understood that in step S20, the graphene layer-coated platinum catalyst, the platinum source, and the solvent are mixed and uniformly dispersed by ultrasonic dispersion.

[0092] It can be understood that after step S20 ends, steps S10 and S20 can be continued to be performed in a loop to deposit a graphene layer on the surface of the composite material prepared in the last step and load platinum particles on the surface of the graphene layer prepared in the last step.

[0093] For example, in some examples, after step S20 ends, the method further includes:

[0094] Step S30: using an organic compound in a liquid state at room temperature as a carbon source, placing the organic compound in a first tube furnace and the composite material prepared in step S20 in a second tube furnace, connecting the first tube furnace and the second tube furnace through a quartz tube, and heating the first tube furnace and the second tube furnace 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, thereby preparing a graphene layer-coated platinum catalyst and a second graphene layer-coated platinum catalyst.

[0095] In some examples, after step S30 ends, the method further includes:

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

[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 finally prepared platinum composite catalyst has better catalytic performance than when the outermost layer is a graphene layer or the outermost layer is a platinum particle. The more layers of deposition, 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 1-10 layers of graphene layers.

[0099] The preparation method of the platinum composite catalyst provided in the application can effectively improve the loading amount of platinum particles, thereby effectively improving the catalytic activity of the platinum composite catalyst. Through layer-by-layer coating and loading, the stability of the platinum composite catalyst can be effectively improved.

[0100] An embodiment of the application provides a platinum composite catalyst prepared by the preparation method of the platinum composite catalyst.

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

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

[0103] It can be understood that the total mass content of the platinum particles in the platinum composite catalyst refers to the percentage of the total mass of the platinum particles in the platinum composite catalyst in the total mass of the platinum composite catalyst; it can be further understood that the platinum composite catalyst at least includes the first platinum particles and the second platinum particles, that is, the total mass of the platinum particles in the platinum composite catalyst at least includes 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 examples, the average particle size of the platinum particles in the platinum composite catalyst is 5 nm to 20 nm.

[0105] It can be understood that the platinum composite catalyst at least includes the first platinum particles and the second platinum particles, and the first platinum particles and the second platinum particles respectively independently satisfy the above 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 by the application has high catalytic activity and good stability.

[0107] An embodiment of the application provides a membrane electrode assembly, which comprises a proton exchange membrane, a catalytic layer, and a gas diffusion layer, the catalytic layer is arranged on at least one side of the proton exchange membrane, the gas diffusion layer is arranged on a side of the catalytic layer away from the proton exchange membrane, and the catalytic layer comprises the platinum composite catalyst.

[0108] The membrane electrode assembly provided by the application has high catalytic activity and good stability due to the inclusion of the platinum composite catalyst.

[0109] An embodiment of the application provides a fuel cell, which comprises an anode plate, a cathode plate, and the membrane electrode assembly, and the anode plate and the cathode plate are arranged on two sides of the membrane electrode assembly.

[0110] The fuel cell provided by the application has high catalytic activity and good stability due to the inclusion of the membrane electrode assembly.

[0111] The application will be further described in detail below with reference to the specific embodiments, but the embodiments of the application are not limited thereto.

[0112] Example 1

[0113] (1) 0.5 g graphene was added into 0.5 mg / mL chloroplatinic acid ethylene glycol solution, and ultrasonic treatment was performed for 1 h to make it uniformly dispersed, to prepare a mixed solution;

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

[0115] (3) A quartz tube was used to connect tube furnace A and tube furnace B, the airtightness was checked, then 100 mL anhydrous ethanol was placed in tube furnace A, and 0.1 g Pt / Gr prepared in step (2) was placed in tube furnace B; the tube furnace was pumped to a vacuum state, the tube furnace was closed, tube furnace A was heated to 90℃, tube furnace B was heated to 500℃, and kept for 30 min to deposit a graphene layer on the surface of the Pt / Gr prepared in step (2), to obtain a graphene layer coated platinum catalyst C@Pt / Gr (including graphene-platinum-graphene structure from outside to inside);

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

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

[0118] Example 2

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

[0120] Example 3

[0121] The same as Example 1, except that in step (3), 100 mL acetonitrile was placed in tube furnace A.

[0122] Example 4

[0123] The same as Example 1, except that in step (3), tube furnace A was heated to 150℃, tube furnace B was heated to 300℃, and kept for 30 min.

[0124] Example 5

[0125] The same as Example 1, except that the graphene-platinum composite catalyst with the structure of platinum-graphene-platinum-graphene from outside to inside prepared in step (4) of Example 1 is continuously repeated with step (3) and step (4).

[0126] Comparative Example 1

[0127] Commercial platinum-carbon catalyst (Hesen catalyst).

[0128] Comparative Example 2

[0129] (1) 0.5 g of graphene was added to a 0.5 mg / mL ethylene glycol solution of chloroplatinic acid, and ultrasonic treatment was performed for 1 h to uniformly disperse the graphene, to prepare a mixed solution;

[0130] (2) The mixed solution prepared in step (1) was transferred to an oil bath, nitrogen was introduced, and heating was performed at 120°C 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) 100 mL of anhydrous ethanol and 0.1 g of the Pt / Gr prepared in step (2) were placed in a tube furnace; the tube furnace was evacuated to a vacuum state, the tube furnace was closed, the tube furnace was heated to 150°C, and the temperature was maintained for 30 min, to deposit a graphene layer on the surface of the Pt / Gr prepared in step (2), to obtain a graphene layer-coated platinum catalyst C@Pt / Gr (including a graphene-platinum-graphene structure from outside to inside);

[0132] (4) The C@Pt / Gr prepared in step (3) was added to a 0.5 mg / mL ethylene glycol solution of chloroplatinic acid, and ultrasonic treatment was performed for 1 h, nitrogen was introduced, and heating was performed at 120°C 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 the structure of platinum-graphene-platinum-graphene from outside to inside.

[0133] Comparative Example 3

[0134] (1) 0.5 g of graphene was added to a 0.5 mg / mL ethylene glycol solution of chloroplatinic acid, and ultrasonic treatment was performed for 1 h to uniformly disperse the graphene, to prepare a mixed solution;

[0135] (2) The mixed solution prepared in step (1) was transferred to an oil bath, nitrogen was introduced, and heating was performed at 120°C 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) Put 100 mL of anhydrous ethanol and 0.1 g of the Pt / Gr prepared in step (2) into a tube furnace; evacuate the tube furnace to a vacuum state, close the tube furnace, heat the tube furnace to 500°C, and keep 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 layer coated platinum catalyst C@Pt / Gr (including a graphene-platinum-graphene structure from outside to inside);

[0137] (4) Put the C@Pt / Gr prepared in step (3) into a 0.5 mg / mL ethylene glycol chloroplatinic acid solution, ultrasonic for 1 h, then pass nitrogen gas, heat to 120°C, and keep the temperature for 45 min; after the reaction is completed, centrifuge the reaction solution, put the solid product into a drying box, dry at 75°C for 24 h, to obtain a graphene-platinum catalyst with a platinum-graphene-platinum-graphene structure from outside to inside.

[0138] Comparative Example 4

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

[0140] (2) Transfer the mixed solution prepared in step (1) into an oil bath pot, pass nitrogen gas, heat to 120°C, and keep the temperature for 45 min; after the reaction is completed, centrifuge the reaction solution, put the solid product into a drying box, dry at 75°C for 24 h, to obtain a graphene-based platinum catalyst (Pt / Gr);

[0141] (3) Use a quartz tube to connect tube furnace A with tube furnace B, check the airtightness, then put 100 mL of anhydrous ethanol into tube furnace A and 0.1 g of the Pt / Gr prepared in step (2) into tube furnace B; evacuate the tube furnace to a vacuum state, close the tube furnace, heat tube furnace A to 90°C and tube furnace B to 500°C, and keep 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 layer coated platinum catalyst C@Pt / Gr (including a graphene-platinum-graphene structure from outside to inside).

[0142] Comparative Example 5

[0143] The same as Example 3, except that in step (3), methane is used as a carbon source, and the specific process is as follows:

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

[0145] (2) The mixed solution prepared in step (1) is transferred to an oil bath pot, nitrogen is introduced, heated to 120 DEG C, and kept for 45 min; after the reaction is completed, the reaction solution is centrifuged, the solid product is put into a drying box, dried at 75 DEG C for 24 h, and a graphene-based platinum catalyst (Pt / Gr) is obtained;

[0146] (3) 0.1 g of the Pt / Gr prepared in step (2) is put into a tube furnace, the tube furnace is pumped to a vacuum state, methane gas is introduced at a speed of 60 mL / min, the tube furnace is heated to 500 DEG C, and kept for 50 min, and C@Pt / Gr is obtained;

[0147] (4) The C@Pt / Gr prepared in step (3) is added to a 0.5 mg / mL ethylene glycol solution of chloroplatinic acid, ultrasonic is performed for 1 h, nitrogen is introduced, heated to 120 DEG C, and kept for 45 min; after the reaction is completed, the reaction solution is centrifuged, the solid product is put into a drying box, dried at 75 DEG C for 24 h, and a graphene-platinum composite catalyst with a platinum-graphene-platinum-graphene structure from the outside to the inside is obtained.

[0148] Comparative Example 6

[0149] The same as Comparative Example 3, except that in step (3), the tube furnace is heated to 900 DEG C.

[0150] The catalyst coated glassy carbon electrode prepared in each example and comparative example is used as a working electrode, a platinum sheet electrode is used as a counter electrode, a saturated calomel electrode is used as a reference electrode, and 0.5 mol / L H2SO4 is used as an electrolyte for linear voltammetry scan test.

[0151] Figure 2 The linear voltammetry scan graphs of the catalysts prepared in Example 1 and Comparative Example 1 are shown in FIG. 1. Figure 2 It can be seen that the half-wave potential of the platinum composite catalyst prepared in Example 1 is obviously better than that of the commercial platinum carbon catalyst, and the catalytic performance is better. The half-wave potential refers to the size of 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 30000 cycles at 0.45 V is shown in FIG. 2. 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. Figure 3

[0153] Figure 4 The linear voltammetry scan graphs of the catalysts prepared in Example 1 and Example 2 are shown in FIG. 3. ​

[0154] The total mass content of platinum, the half-wave potential and the current density loss rate after 30000 cycles of the catalyst prepared in each example and the comparative example are shown in Table 1.

[0155] Table 1

[0156]

[0157] From Table 1, it can be seen that the catalyst prepared in each example has higher platinum loading, higher half-wave potential, better catalytic activity and higher stability compared with the comparative example.

[0158] Each technical feature of the above-described examples can be combined arbitrarily. In order to make the description simple, all possible combinations of each technical feature in the above-described examples are not described, however, as long as the combinations of the technical features do not contradict, they should be considered as the scope of the present disclosure.

[0159] The above-described examples only express several embodiments of the present application, facilitate specific and detailed understanding of the technical solutions of the present application, but should not be understood as a limitation on the scope of patent protection. It should be noted that for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these are within the scope of protection of the present application. It should be understood that the technical solutions obtained by the skilled person in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided in the present application are within the scope of protection of the appended claims of the present application. Therefore, the scope of protection of the patent of the present application should be based on the content of the appended claims, and the description and drawings can be used to explain the content of the claims.

Claims

1. A method for preparing a platinum composite catalyst, characterized by, The method comprises the following steps. Providing a graphene-based platinum catalyst comprising a graphene carrier and first platinum particles supported on the surface of the graphene carrier; An organic compound in liquid state at room temperature is used as a carbon source, and the organic compound is placed in a first tube furnace, and the graphene-based platinum catalyst is placed in a second tube furnace, the first tube furnace and the second tube furnace are connected by a quartz tube, and the first tube furnace and the second tube furnace are heated respectively 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; The temperature of the first tube furnace is 80-150°C, and the temperature of the second tube furnace is 200-500°C. Second platinum particles are supported in the graphene layer and the pores of the graphene carrier by using a platinum source and a sol-gel method.

2. The production method according to claim 1, wherein The organic compound comprises at least one of an alcohol with 1-6 carbon atoms and a nitrile with 1-4 carbon atoms.

3. The production method according to claim 2, wherein The organic compound comprises at least one of methanol, ethanol and acetonitrile.

4. The production method according to claim 1, wherein The volume of the organic compound to the mass of the graphene-based platinum catalyst is 10-100 mL:1 g.

5. The production method according to any one of claims 1 to 4, wherein The temperature of the first tube furnace is 90-150°C.

6. The production method according to claim 5, wherein The temperature of the second tube furnace is 300-500°C.

7. The production method according to claim 5, wherein The heating time is 0.1-10 h.

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

9. The production method according to any one of claims 1 to 4, 6 to 7, wherein The platinum source comprises at least one of chloroplatinic acid, ammonium hexachloroplatinate, platinum acetylacetonate, potassium chloroplatinate, platinum acetylacetonate and ammonium tetrachloroplatinate.

10. A platinum composite catalyst characterized by, The platinum composite catalyst is prepared by using the preparation method in any one of claims 1-9.

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

12. A membrane electrode assembly, characterized by, The membrane electrode assembly comprises a proton exchange membrane, a catalyst layer and a gas diffusion layer, the catalyst layer is arranged on at least one side of the proton exchange membrane, and the gas diffusion layer is arranged on the side of the catalyst layer away from the proton exchange membrane.

13. A fuel cell characterized by comprising: The membrane electrode assembly comprises an anode plate and a cathode plate arranged on the two sides of the membrane electrode assembly.

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