Graphene-platinum composite material and preparation method thereof, platinum catalyst, membrane electrode assembly and fuel cell

Abstract

The invention relates to a graphene-platinum composite material and a preparation method thereof, a platinum catalyst, a membrane electrode assembly and a fuel cell. The preparation method of the graphene-platinum composite material comprises the following steps: carrying out electroplating treatment by taking nitrogen-doped graphene aerogel as a substrate, and depositing platinum nanoparticles on the nitrogen-doped graphene aerogel to prepare the graphene-platinum composite material; the current density of the electroplating treatment is 0.1 A / dm < 2 >-2 A / dm < 2 >. Nitrogen-doped graphene aerogel is used as a substrate for electroplating treatment, and platinum nanoparticles can be embedded into the nitrogen-doped graphene aerogel by controlling the current density of the electroplating treatment, so that the platinum nanoparticles are in full contact with the nitrogen-doped graphene aerogel, and the utilization rate of platinum is increased; and by controlling the current density of electroplating treatment, the morphology of the embedded platinum nanoparticles can be effectively controlled, so that the catalytic performance and the stability performance of the graphene-platinum composite material are effectively improved.

Description

Technical Field

[0001] The present application relates to the field of materials technology, and particularly to a graphene-platinum composite material, a preparation method thereof, a platinum catalyst, a membrane electrode assembly and a fuel cell. Background Art

[0002] As an efficient and clean energy conversion device, fuel cells have received extensive attention in recent years. Among them, proton exchange membrane fuel cells (PEMFCs) have become a research hotspot due to their high conversion efficiency, high power density and low pollution. The performance and cost of fuel cells largely depend on the performance of the catalyst. The performance is mainly limited by the oxygen reduction reaction (ORR) at the cathode, and its cost is also limited by the cathode catalyst. At present, platinum (Pt)-based catalysts are the most commonly used cathode catalysts. However, the catalytic performance of traditional platinum-based catalysts needs to be further improved. Summary of the Invention

[0003] Based on this, the present application provides a graphene-platinum composite material with better catalytic performance, a preparation method thereof, a platinum catalyst, a membrane electrode assembly and a fuel cell.

[0004] The technical solution of the present application to solve the above technical problems is as follows.

[0005] The first aspect of the present application provides a preparation method of a graphene-platinum composite material, including the following steps:

[0006] Performing electroplating treatment with a nitrogen-doped graphene aerogel as a substrate to deposit platinum nanoparticles on the nitrogen-doped graphene aerogel to prepare a graphene-platinum composite material; the current density of the electroplating treatment is 0.1 A / dm 2 ~2 A / dm 2 .

[0007] In some embodiments, in the preparation method of the graphene-platinum composite material, the platinum nanoparticles are deposited inside and on the surface of the nitrogen-doped graphene aerogel.

[0008] In some embodiments, in the preparation method of the graphene-platinum composite material, the electroplating treatment time is 5 min to 60 min.

[0009] In some embodiments, in the preparation method of the graphene-platinum composite material, the electroplating treatment includes:

[0010] Performing electroplating treatment with the nitrogen-doped graphene aerogel as the cathode and platinum as the anode in a platinum-containing electroplating solution.

[0011] In some embodiments, in the preparation method of the graphene-platinum composite material, the platinum-containing electroplating solution includes a platinum salt and a stabilizer;

[0012] Optionally, the platinum salt includes at least one of chloroplatinic acid and its alkali metal salts, chloroplatinous acid and its alkali metal salts, platinum sulfate and its alkali metal salts, platinous sulfite acid and its alkali metal salts, and dinitrodiammineplatinum;

[0013] Optionally, the concentration of the platinum salt in the platinum-containing electroplating solution is 5 g / L to 20 g / L;

[0014] Optionally, the stabilizer includes at least one of sulfamic acid and ammonium sulfamate;

[0015] Optionally, the concentration of the stabilizer in the platinum-containing electroplating solution is 2 g / L to 20 g / L.

[0016] In some embodiments, in the method for preparing the graphene-platinum composite material, the preparation of the nitrogen-doped graphene aerogel includes the following steps:

[0017] Mixing a graphene oxide solution and a nitrogen source for hydrothermal reaction to prepare a graphene hydrogel;

[0018] Freeze-drying the graphene hydrogel to prepare the nitrogen-doped graphene aerogel.

[0019] In some embodiments, in the method for preparing the graphene-platinum composite material, after the electroplating treatment, it further includes ball-milling the composite material obtained by the electroplating treatment to obtain the graphene-platinum composite material.

[0020] The second aspect of the present application provides a graphene-platinum composite material, including a nitrogen-doped graphene aerogel and platinum nanoparticles located inside and / or on the surface of the nitrogen-doped graphene aerogel.

[0021] In some embodiments, in the graphene-platinum composite material, the mass content of the platinum nanoparticles in the graphene-platinum composite material is 15% to 70%; and / or,

[0022] The average particle size of the platinum nanoparticles in the graphene-platinum composite material is 5 nm to 20 nm.

[0023] The third aspect of the present application provides a platinum catalyst, including the graphene-platinum composite material provided in the second aspect.

[0024] The fourth aspect of the present application provides a membrane electrode assembly, including a proton exchange membrane, a catalytic layer, and a gas diffusion layer. The catalytic layer is disposed on at least one side of the proton exchange membrane, the gas diffusion layer is disposed on the side of the catalytic layer away from the proton exchange membrane, and the catalytic layer includes the platinum catalyst provided in the third aspect.

[0025] The fifth aspect of the present application provides a fuel cell, which includes an anode plate, a cathode plate, and the membrane electrode assembly provided by the fourth aspect. The anode plate and the cathode plate are respectively disposed on both sides of the membrane electrode assembly.

[0026] Advantageous effects:

[0027] In the preparation method of the graphene-platinum composite material of the present application, electroplating treatment is carried out using nitrogen-doped graphene aerogel as the substrate, and by controlling the current density of the electroplating treatment, platinum nanoparticles can be embedded into the interior of the nitrogen-doped graphene aerogel, enabling the platinum nanoparticles to be in full contact with the nitrogen-doped graphene aerogel, thereby improving the utilization rate of platinum; and by controlling the current density of the electroplating treatment, the morphology of the embedded platinum nanoparticles can be effectively controlled, thus effectively enhancing the catalytic performance and stability of the graphene-platinum composite material. Description of the drawings

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application and more comprehensively understand the present application and its advantageous effects, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings without creative efforts based on these drawings.

[0029] Figure 1 Linear voltammetry scan diagrams of the graphene-platinum composite catalyst prepared in Example 1 and a commercial platinum-carbon catalyst. Detailed implementation manners

[0030] The present application will be further described in detail below in combination with the implementation manners and embodiments. It should be understood that these implementation manners and embodiments are only used to illustrate the present application and not to limit the scope of the present application. The purpose of providing these implementation manners and embodiments is to make the understanding of the disclosed content of the present application more thorough and comprehensive.

[0031] It should also be understood that the present application can be implemented in many different forms and is not limited to the implementation manners and embodiments described herein. Those skilled in the art can make various changes or modifications without departing from the connotation of the present application, and the equivalent forms obtained also fall within the protection scope of the present application. For example, the features described as part of one implementation manner can be combined in a suitable manner with another implementation manner to produce a new implementation manner. In addition, in the following description, a large number of specific details are given 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.

[0032] 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 terms used in the specification of this application are for the purpose of describing embodiments and examples only, and are not intended to limit this application.

[0033] Unless otherwise specified or there is a contradiction, the terms or phrases used herein have the following meanings:

[0034] In this application, the terms "a plurality of", "a variety of", "multiple times", etc., unless otherwise specified, mean greater than 2 or equal to 2 in quantity. For example, "one or more" means one or greater than or equal to two.

[0035] As used herein, "combinations thereof", "any combination thereof", "any combination mode thereof", etc. include all suitable combination modes of any two or more than two items in the listed items.

[0036] In this application, the "suitable" in "suitable combination mode", "suitable mode", "any suitable mode", etc. is subject to being able to implement the technical solution of this application, solve the technical problems of this application, and achieve the expected technical effects of this application.

[0037] In this application, "preferred", "better", "more preferably", "it is advisable" are only used to describe embodiments or examples with better effects, and it should be understood that they do not constitute a limitation on the protection scope of this application. If "preferred" appears in a technical solution for multiple times, unless otherwise specified and there is no contradiction or mutual restriction relationship, each "preferred" is independent of each other.

[0038] In this application, "further", "even further", "especially", etc. are used for descriptive purposes and represent differences in content, but should not be understood as a limitation on the protection scope of this application.

[0039] In this application, "optionally", "optional", "optional" mean optional, that is, it refers to any one of the two parallel options of "yes" or "no". If "optional" appears in a technical solution for multiple times, unless otherwise specified and there is no contradiction or mutual restriction relationship, each "optional" is independent of each other.

[0040] In this application, in "the first aspect", "the second aspect", "the third aspect", "the fourth aspect", etc., the terms "first", "second", "third", "fourth", etc. are only used for descriptive 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", 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.

[0041] In this application, among the technical features described in an open-ended manner, there are both closed technical solutions composed of the listed features and open technical solutions containing the listed features.

[0042] In this application, regarding numerical intervals (i.e., numerical ranges), unless otherwise specified, the distribution of the selectable numerical values within the numerical interval is considered continuous, and it includes the two numerical endpoints of the numerical interval (i.e., the minimum value and the maximum value), as well as each numerical value between these two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to the integers within the numerical interval, it includes the two endpoint integers of the numerical range, as well as 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 ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein. The "numerical values" in the numerical interval can be any quantitative values, such as numbers, percentages, ratios, etc. The "numerical interval" is allowed to broadly include numerical interval types such as percentage intervals, ratio intervals, and ratio value intervals.

[0043] The temperature parameter in this application, unless otherwise specified, allows both constant temperature treatment and variation 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 ranges such as ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are allowed.

[0044] In this application, the term "room temperature" or "normal temperature" generally refers to 4°C to 35°C, such as 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.

[0045] In this application, regarding the units of data ranges, if there is only a unit after the right endpoint, it means that the units of the left endpoint and the right endpoint are the same. For example, 3 to 5 h means that the units of the left endpoint "3" and the right endpoint "5" are both h (hours).

[0046] All documents mentioned in this application are incorporated herein by reference as if each document was individually incorporated by reference. Unless it conflicts with the invention purpose and / or technical solution of this application, the cited documents involved in this application are cited for all their contents and all purposes. When this application involves cited documents, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also incorporated by reference. When this application involves cited documents, the examples and preferred methods of the relevant technical features cited can also be incorporated into this application as references, but only to the extent that this application can be implemented. It should be understood that when the cited content conflicts with the description in this application, this application shall prevail or be amended adaptively according to the description of this application.

[0047] The quality or weight of the relevant components mentioned in the specification of the embodiments of this application not only can refer to the specific content of each component, but also can represent the proportional relationship of the quality or weight between each component. Therefore, as long as the content of the relevant components in the specification of the embodiments of this application is scaled up or down proportionally, it is within the scope disclosed in the specification of the embodiments of this application. Specifically, the quality or weight described in the specification of the embodiments of this application can be units well-known in the chemical industry such as μg, mg, g, kg, etc.

[0048] Through research and analysis, it is considered that the reasons for the low catalytic activity and stability of traditional platinum-based catalysts include:

[0049] (1) Traditional platinum-based catalysts are easily poisoned by toxic gases, thus affecting battery performance; problems such as durability decline will occur after long-term use;

[0050] (2) Traditional platinum catalysts may form surface oxides in the working environment, and these oxides will change the electronic structure and activity of the catalyst, resulting in catalyst deactivation and seriously reducing the stability and catalytic activity of the catalyst.

[0051] One embodiment of this application provides a preparation method of a graphene-platinum composite material, including the following steps:

[0052] Using nitrogen-doped graphene aerogel as a substrate for electroplating treatment to deposit platinum nanoparticles on the nitrogen-doped graphene aerogel to prepare a graphene-platinum composite material; the current density of the electroplating treatment is 0.1 A / dm 2 ~2 A / dm 2 .

[0053] The preparation method of the graphene-platinum composite material of the present application electroplates with a nitrogen-doped graphene aerogel as the substrate, and by controlling the current density of the electroplating treatment, platinum nanoparticles can be embedded inside the nitrogen-doped graphene aerogel, enabling the platinum nanoparticles to be in full contact with the nitrogen-doped graphene aerogel, thereby improving the utilization rate of platinum; and by controlling the current density of the electroplating treatment, the morphology of the embedded platinum nanoparticles can be effectively controlled, thus effectively enhancing the catalytic performance and stability of the graphene-platinum composite material.

[0054] Using a nitrogen-doped graphene aerogel as the substrate provides active sites for the deposition of platinum nanoparticles, facilitating the deposition and fixation of platinum nanoparticles; if directly using a (non-nitrogen-doped) graphene aerogel as the substrate, there are a lack of active sites, which is not conducive to the deposition and fixation of platinum nanoparticles, thus affecting the catalytic performance and stability of the graphene-platinum composite material.

[0055] The graphene-platinum composite material prepared by the preparation method of the graphene-platinum composite material of the present application has strong anti-toxicity ability, small loss of activity after multiple cycles, and high stability.

[0056] It can be understood that the current density of the electroplating treatment includes but is not limited to 0.1 A / dm 2 、0.2 A / dm 2 、0.3 A / dm 2 、0.4 A / dm 2 、0.5 A / dm 2 、0.6 A / dm 2 、0.7 A / dm 2 、0.8 A / dm 2 、0.9 A / dm 2 、1.0 A / dm 2 、1.1 A / dm 2 、1.2 A / dm 2 、1.3 A / dm 2 、1.4 A / dm 2 、1.5 A / dm 2 、1.6 A / dm 2 、1.7 A / dm 2 、1.8 A / dm 2 、1.9 A / dm 2 、2.0 A / dm 2 ; in some examples, it can be within the range formed by any two of these point values as the end values, and the same applies hereinafter.

[0057] In some of these examples, in the preparation method of the graphene-platinum composite material, the current density of the electroplating treatment is 0.5 A / dm 2 ~2 A / dm2 。

[0058] By controlling the current density of the electroplating treatment, the distribution and morphology of platinum nanoparticles can be controlled, enhancing the catalytic performance and stability of the graphene-platinum composite material; if the current density of the electroplating treatment is set improperly, the current efficiency will be reduced, resulting in a poor electroplating effect.

[0059] In some of these examples, in the method for preparing the graphene-platinum composite material, platinum nanoparticles are deposited inside and on the surface of the nitrogen-doped graphene aerogel.

[0060] In some of these examples, in the method for preparing the graphene-platinum composite material, the time of the electroplating treatment is 5 min to 60 min.

[0061] It can be understood that the time of the electroplating treatment includes but is not limited to 5 min, 8 min, 10 min, 12 min, 15 min, 18 min, 20 min, 22 min, 25 min, 28 min, 30 min, 32 min, 35 min, 38 min, 40 min, 42 min, 45 min, 48 min, 50 min, 52 min, 55 min, 58 min, 60 min.

[0062] In some of these examples, in the method for preparing the graphene-platinum composite material, the time of the electroplating treatment is 5 min to 60 min.

[0063] The time of the electroplating treatment is 5 min to 30 min.

[0064] In some of these examples, in the method for preparing the graphene-platinum composite material, the electroplating treatment includes:

[0065] Using the nitrogen-doped graphene aerogel as the cathode and platinum as the anode, electroplating treatment is carried out in a platinum-containing electroplating solution.

[0066] In some of these examples, in the method for preparing the graphene-platinum composite material, the platinum-containing electroplating solution includes a platinum salt and a stabilizer.

[0067] In some of these examples, in the method for preparing the graphene-platinum composite material, the platinum salt includes at least one of chloroplatinic acid and its alkali metal salts, chloroplatinous acid and its alkali metal salts, platinum sulfate and its alkali metal salts, platinous sulfite acid and its alkali metal salts, and dinitrodiammineplatinum.

[0068] Optionally, the alkali metal salts of chloroplatinic acid include but are not limited to at least one of lithium chloroplatinate, sodium chloroplatinate, potassium chloroplatinate, rubidium chloroplatinate, and cesium chloroplatinate.

[0069] Optionally, the alkali metal salts of chloroplatinic acid include but are not limited to at least one of lithium chloroplatinate, sodium chloroplatinate, potassium chloroplatinate, rubidium chloroplatinate, and cesium chloroplatinate.

[0070] Optionally, the alkali metal salts of platinum sulfate include but are not limited to at least one of lithium platinum sulfate, sodium platinum sulfate, potassium platinum sulfate, rubidium platinum sulfate, and cesium platinum sulfate.

[0071] Optionally, the alkali metal salts of platinous sulfite include but are not limited to at least one of lithium platinous sulfite, sodium platinous sulfite, potassium platinous sulfite, rubidium platinous sulfite, and cesium platinous sulfite.

[0072] In some of the examples, in the method for preparing the graphene-platinum composite material, the concentration of the platinum salt in the platinum-containing electroplating solution is 5 g / L to 20 g / L.

[0073] It can be understood that the concentration of the platinum salt in the platinum-containing electroplating solution includes but is not limited to 5 g / L, 6 g / L, 7 g / L, 8 g / L, 9 g / L, 10 g / L, 11 g / L, 12 g / L, 13 g / L, 14 g / L, 15 g / L, 16 g / L, 17 g / L, 18 g / L, 19 g / L, and 20 g / L.

[0074] By controlling the concentration of the platinum salt in the platinum-containing electroplating solution, the size of the finally deposited platinum nanoparticles can be controlled, avoiding the influence on the catalytic performance due to too large particle size.

[0075] It can be further understood that by controlling the concentration of the platinum salt in the platinum-containing electroplating solution and the time of the electroplating treatment, the platinum content of the finally obtained graphene-platinum composite material can be controlled.

[0076] In some of the examples, in the method for preparing the graphene-platinum composite material, the stabilizer includes at least one of sulfamic acid and ammonium sulfamate.

[0077] In some of the examples, in the method for preparing the graphene-platinum composite material, the concentration of the stabilizer in the platinum-containing electroplating solution is 2 g / L to 20 g / L.

[0078] It can be understood that the concentration of the stabilizer in the platinum-containing electroplating solution includes but is not limited to 2 g / L, 3 g / L, 4 g / L, 5 g / L, 6 g / L, 7 g / L, 8 g / L, 9 g / L, 10 g / L, 11 g / L, 12 g / L, 13 g / L, 14 g / L, 15 g / L, 16 g / L, 17 g / L, 18 g / L, 19 g / L, and 20 g / L.

[0079] In some of these examples, in the method for preparing the graphene-platinum composite material, the platinum-containing electroplating solution includes sulfamic acid and ammonium sulfamate, the concentration of sulfamic acid is 2 g / L to 10 g / L, and the concentration of ammonium sulfamate is 2 g / L to 10 g / L.

[0080] In some of these examples, in the method for preparing the graphene-platinum composite material, the pH value of the platinum-containing electroplating solution is 1 to 2.

[0081] In some of these examples, sulfuric acid or ammonia water is used to adjust the pH value of the platinum-containing electroplating solution.

[0082] It can be understood that electroplating treatment is carried out using an electrolytic cell.

[0083] In some of these examples, in the method for preparing the graphene-platinum composite material, a copper plate plated with platinum fixture is used to fix the nitrogen-doped graphene aerogel.

[0084] In some of these examples, in the method for preparing the graphene-platinum composite material, the preparation of the nitrogen-doped graphene aerogel includes the following steps:

[0085] Mix the graphene oxide solution and the nitrogen source and carry out a hydrothermal reaction to prepare a graphene hydrogel;

[0086] Freeze-dry the graphene hydrogel to prepare the nitrogen-doped graphene aerogel.

[0087] It can be understood that in the step of mixing the graphene oxide solution and the nitrogen source, stirring, ultrasonic waves, etc. can be used to promote their uniform mixing.

[0088] In some of these examples, in the preparation of the nitrogen-doped graphene aerogel, the graphene oxide solution includes an aqueous graphene oxide solution.

[0089] In some of these examples, in the preparation of the nitrogen-doped graphene aerogel, the nitrogen source includes at least one of urea and ammonia water.

[0090] In some of these examples, in the preparation of the nitrogen-doped graphene aerogel, the concentration of the graphene oxide solution is 0.5 mg / mL to 5 mg / mL.

[0091] It can be understood that the concentration of the graphene oxide solution includes but is not limited to 0.5 mg / mL, 0.8 mg / mL, 1 mg / mL, 1.2 mg / mL, 1.5 mg / mL, 1.8 mg / mL, 2 mg / mL, 2.2 mg / mL, 2.5 mg / mL, 2.8 mg / mL, 3 mg / mL, 3.2 mg / mL, 3.5 mg / mL, 3.8 mg / mL, 4 mg / mL, 4.2 mg / mL, 4.5 mg / mL, 4.8 mg / mL, 5 mg / mL.

[0092] Optionally, the concentration of the graphene oxide solution is 0.5 mg / mL to 2 mg / mL.

[0093] In some examples, in the preparation of the nitrogen-doped graphene aerogel, the mass ratio of graphene oxide in the graphene oxide solution to the nitrogen source is 1:2 to 5.

[0094] It can be understood that the mass ratio of graphene oxide in the graphene oxide solution to the nitrogen source includes but is not limited to 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5.

[0095] Optionally, the mass ratio of graphene oxide in the graphene oxide solution to the nitrogen source is 1:3 to 4.

[0096] In some examples, in the preparation of the nitrogen-doped graphene aerogel, the temperature of the hydrothermal reaction is 90°C to 200°C.

[0097] It can be understood that the temperature of the hydrothermal reaction includes but is not limited to 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C.

[0098] Optionally, the temperature of the hydrothermal reaction is 90°C to 150°C.

[0099] In some examples, in the preparation of the nitrogen-doped graphene aerogel, the time of the hydrothermal reaction is 12 h to 48 h. Optionally, the time of the hydrothermal reaction is 12 h to 24 h.

[0100] In some examples, in the preparation of the nitrogen-doped graphene aerogel, before freeze-drying the graphene hydrogel, it further includes the step of soaking the graphene hydrogel in water. Further, the soaking time is 12 h to 48 h. Optionally, the soaking time is 12 h to 24 h.

[0101] In some examples, in the preparation method of the graphene-platinum composite material, electroplating treatment is performed on at least one side of the nitrogen-doped graphene aerogel.

[0102] Optionally, electroplating treatment is performed on both sides of the nitrogen-doped graphene aerogel.

[0103] It can be understood that when electroplating treatment is performed on both sides of the nitrogen-doped graphene aerogel, electroplating treatment can be performed on both sides simultaneously; or electroplating treatment can be first performed on one side of the nitrogen-doped graphene aerogel, and then the nitrogen-doped graphene aerogel is flipped to perform electroplating treatment on the other side of the graphene aerogel.

[0104] In some of these examples, in the method for preparing the graphene-platinum composite material, after the electroplating treatment, it further includes ball-milling the composite material obtained by the electroplating treatment to obtain the graphene-platinum composite material.

[0105] In some of these examples, the rotation speed of the ball-milling is 100 rpm to 500 rpm, and the time is 5 h to 20 h.

[0106] One embodiment of the present application provides a graphene-platinum composite material, which is prepared by using the above-mentioned method for preparing the graphene-platinum composite material.

[0107] Another embodiment of the present application provides a graphene-platinum composite material, including a nitrogen-doped graphene aerogel and platinum nanoparticles located inside and / or on the surface of the nitrogen-doped graphene aerogel.

[0108] It can be understood that the "platinum nanoparticles located inside and / or on the surface of the nitrogen-doped graphene aerogel" means that the platinum nanoparticles are located in at least one of the inside and the surface of the nitrogen-doped graphene aerogel.

[0109] In some of these examples, the mass content of the platinum nanoparticles in the graphene-platinum composite material is 15% to 70%.

[0110] It can be understood that the mass content of the platinum nanoparticles in the graphene-platinum composite material includes, but is not limited to, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, 50%, 52%, 55%, 58%, 60%, 62%, 65%, 68%, 70%.

[0111] In some of these examples, the average particle size of the platinum nanoparticles in the graphene-platinum composite material is 5 nm to 20 nm.

[0112] It can be understood that the average particle size of the platinum nanoparticles in the graphene-platinum composite material includes, but is not limited to, 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, 11nm, 12nm, 13nm, 14nm, 15nm, 16nm, 17nm, 18nm, 19nm, 20nm.

[0113] One embodiment of the present application provides the application of the above-mentioned graphene-platinum composite material in the preparation of a platinum catalyst. Another embodiment of the present application provides a platinum catalyst, including the above-mentioned graphene-platinum composite material.

[0114] The platinum catalyst of the present application includes the graphene-platinum composite material provided by the present application, and thus has at least the same advantages as the above-mentioned graphene-platinum composite material.

[0115] One embodiment of the present application provides a membrane electrode assembly, which includes a proton exchange membrane, a catalytic layer, and a gas diffusion layer. The catalytic layer is disposed on at least one side of the proton exchange membrane, and the gas diffusion layer is disposed on the side of the catalytic layer away from the proton exchange membrane. The catalytic layer includes the above-mentioned platinum composite material or the above-mentioned platinum catalyst.

[0116] The membrane electrode assembly provided by the present application can endow the membrane electrode assembly with high catalytic activity and stable performance because it includes the above-mentioned graphene-platinum composite material or platinum catalyst.

[0117] One embodiment of the present application provides a fuel cell, which includes an anode plate, a cathode plate, and the above-mentioned membrane electrode assembly. The anode plate and the cathode plate are respectively disposed on both sides of the membrane electrode assembly.

[0118] The fuel cell provided by the present application can endow the fuel cell with high catalytic activity and stable performance because it includes the above-mentioned membrane electrode assembly.

[0119] The following further describes the present application in detail in conjunction with specific embodiments, but the embodiments of the present application are not limited thereto.

[0120] Example 1

[0121] (1) Stir and ultrasonicate an aqueous solution of graphene oxide at 1 mg / mL and urea for 1 h to obtain a mixed solution; the mass ratio of graphene oxide to urea in the graphene oxide solution is 1:3;

[0122] (2) Transfer the mixed solution prepared in step (1) to a reaction kettle, react at 120 °C for 24 h, and obtain a graphene hydrogel after cooling; soak the graphene hydrogel in water for 24 h, and then perform freeze-drying through a freeze dryer to obtain a nitrogen-doped graphene aerogel;

[0123] (3) Use an electrolytic cell of 280 mm×190 mm×260 mm, deposit a platinum layer inside as the anode, and use a copper plate plated with a platinum cathode fixture to fix the nitrogen-doped graphene aerogel as the cathode; platinum-containing electroplating solution: 5 g / L of chloroplatinic acid, 5 / L of sulfamic acid, 5 / L of ammonium sulfamate, the solvent is water, and the pH of the solution is adjusted to 1.2 with sulfuric acid;

[0124] (4) Start electroplating treatment, the applied current density is 0.5 A / dm 2 , and the electroplating time is 30 min;

[0125] (5) Flip the nitrogen-doped graphene aerogel and perform the same electroplating operation on the other side;

[0126] (6) Ball-mill the electroplated nitrogen-doped graphene aerogel at a rotation speed of 300 rpm for 9 h to obtain a graphene-platinum composite catalyst.

[0127] Example 2

[0128] It is basically the same as Example 1, except that in step (4), the current density passed in is 0.1 A / dm 2 .

[0129] Example 3

[0130] It is basically the same as Example 1, except that in step (4), the current density passed in is 1 A / dm 2 .

[0131] Example 4

[0132] It is basically the same as Example 1, except that in step (4), the current density passed in is 2 A / dm 2 .

[0133] Example 5

[0134] It is basically the same as Example 1, except that in step (3), the concentration of chloroplatinic acid in the platinum-containing electroplating solution is 20 g / L; in step (4), the electroplating time is 5 min.

[0135] Comparative Example 1

[0136] It is basically the same as Example 1, except that in step (4), the current density passed in is 0.01 A / dm 2 .

[0137] Comparative Example 2

[0138] It is basically the same as Example 1, except that in step (4), the current density passed in is 5 A / dm 2 .

[0139] Comparative Example 3

[0140] (1) Stir and ultrasonically treat an aqueous solution of graphene oxide (concentration: 1 mg / mL), urea (mass ratio of graphene oxide to urea in the graphene oxide solution is 1:3), an aqueous solution of chloroplatinic acid (concentration: 5 g / L), and the reducing agent ascorbic acid for 1 h to obtain a mixed solution;

[0141] (2) Transfer the mixed solution prepared in step (1) to a reaction kettle, react at 120 °C for 24 h, and obtain a graphene hydrogel after cooling; soak the graphene hydrogel in water for 24 h, and then perform freeze-drying through a freeze dryer to obtain a graphene-platinum composite catalyst (graphene aerogel loaded with platinum nanoparticles).

[0142] Comparative Example 4

[0143] The nitrogen-doped graphene aerogel was added to an aqueous solution of chloroplatinic acid (concentration: 5 g / L), the pH value of the solution was adjusted to 10 - 12, then it was heated by microwave for 65 s until the temperature rose to 130 °C, cooled to room temperature, the pH value was adjusted to 2, filtered, washed, and vacuum dried for 4 h to obtain the graphene-platinum composite catalyst.

[0144] Using the glassy carbon electrode coated with the catalyst prepared in each example and comparative example as the working electrode, the platinum wire electrode as the counter electrode, and the silver chloride electrode as the reference electrode, linear sweep voltammetry tests were carried out using 0.5 mol / L H2SO4 as the electrolyte.

[0145] Figure 1 Figure for the linear sweep voltammetry of the graphene-platinum composite catalyst and commercial platinum-carbon catalyst prepared in Example 1. From Figure 1 It can be seen that the half-wave potential of the graphene-platinum composite catalyst prepared in Example 1 is significantly better than that of the commercial platinum-carbon catalyst, and its catalytic performance is better. Among them, the half-wave potential refers to the magnitude of the voltage (x-axis) corresponding to when the current density (y-axis) of the curve drops to half, and the larger the better.

[0146] The half-wave potential and the current density loss rate after 30,000 cycles of the catalysts prepared in each example and comparative example are shown in Table 1.

[0147] Table 1

[0148]

[0149] As can be seen from Table 1, compared with the comparative examples, the catalysts prepared in each example have a higher half-wave potential, higher catalytic activity, and better stability.

[0150] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as these combinations of technical features do not conflict, they should all be considered as the scope described in this specification.

[0151] The above-described embodiments only represent several implementation manners of the present application, which are convenient for understanding the technical solutions of the present application specifically and in detail, but should not be construed as a limitation on the protection scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope 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 based on the technical solutions provided in the present application are all within the protection scope of the appended claims of the present application. Therefore, the protection scope of the patent of the present application should be subject to the content of the appended claims, and the specification can be used to explain the content of the claims.

Claims

1. A method for preparing a graphene-platinum composite material, characterized in that: The following steps are involved: The nitrogen-doped graphene aerogel is used as a substrate for electroplating to deposit platinum nanoparticles on the graphene aerogel to prepare a graphene-platinum composite material; the current density of the electroplating treatment is 0.1 A / dm 2 ~2 A / dm 2 .

2. The method for preparing the graphene-platinum composite material according to claim 1, wherein: The platinum nanoparticles are deposited inside and on the surface of the nitrogen-doped graphene aerogel.

3. The method for preparing the graphene-platinum composite material according to claim 1, characterized in that: The electroplating treatment time is 5 min to 60 min.

4. The method for preparing the graphene-platinum composite material according to any one of claims 1 to 3, characterized in that: The electroplating process comprises: The nitrogen-doped graphene aerogel is used as a cathode and platinum is used as an anode, and electroplating treatment is performed in a platinum-containing electroplating solution.

5. The method for preparing the graphene-platinum composite material according to claim 4, characterized in that: The platinum-containing electroplating solution includes a platinum salt and a stabilizer; Optionally, the platinum salt includes at least one of chloroplatinic acid and its alkali metal salts, chloroplatinous acid and its alkali metal salts, platinum sulfate and its alkali metal salts, platinous sulfite and its alkali metal salts, and dinitrosodiammineplatinum; Optionally, the concentration of the platinum salt in the platinum-containing electroplating solution is 5 g / L to 20 g / L; Optionally, the stabilizer includes at least one of sulfamic acid and sulfamic acid ammonia; Optionally, the concentration of the stabilizer in the platinum-containing electroplating solution is 2 g / L~20 g / L.

6. The method for preparing the graphene-platinum composite material according to any one of claims 1 to 3 and 5, characterized in that: The preparation of the nitrogen-doped graphene aerogel comprises the following steps: The graphene oxide solution and the nitrogen source are mixed to perform a hydrothermal reaction to prepare a graphene hydrogel; The graphene hydrogel is freeze-dried to prepare the nitrogen-doped graphene aerogel.

7. The method for preparing the graphene-platinum composite material according to claims 1 to 3 and 5, characterized in that: After the electroplating treatment, the method further includes ball milling the composite material obtained by the electroplating treatment to obtain the graphene-platinum composite material.

8. A graphene-platinum composite material, characterized in that: The invention comprises nitrogen-doped graphene aerogel and platinum nanoparticles located inside and / or on the surface of the nitrogen-doped graphene aerogel.

9. The graphene-platinum composite material according to claim 8, characterized in that The mass content of platinum nanoparticles in the graphene-platinum composite material is 15% to 70%; and / or, The average particle size of platinum nanoparticles in the graphene-platinum composite material is 5 nm to 20 nm.

10. A platinum catalyst, characterized in that Comprising the graphene-platinum composite material as described in any one of claims 8 to 9.

11. 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 catalyst as claimed in claim 10.

12. A fuel cell, characterized in that: It comprises an anode plate, a cathode plate and the membrane electrode assembly as claimed in claim 11, wherein the anode plate and the cathode plate are respectively arranged on both sides of the membrane electrode assembly.

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