Carbon-supported catalyst adapting to cold start of hydrogen fuel cell and preparation method of carbon-supported catalyst

Abstract

The invention provides a carbon-supported catalyst adapting to cold start of a hydrogen fuel cell and a preparation method of the carbon-supported catalyst. The carbon-supported catalyst comprises super carbon black particles and catalyst particles supported on the super carbon black particles, the super carbon black particles or the aggregate thereof have any one, any two or all of the following characteristics: (1) the water absorption rate is 1.5-3.0 mL / g; (2) the internal pore volume fraction of the super carbon black particles is greater than or equal to 40%; and (3) the average diameter of internal pores of the super carbon black particles is greater than or equal to 2nm. The hydrogen fuel cell cathode prepared from the catalyst provided by the invention is especially suitable for the low-temperature cold start process of a fuel cell.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen fuel cells, and specifically relates to a carbon-supported catalyst adapted for cold start of hydrogen fuel cells and its preparation method. Background Technology

[0002] Hydrogen fuel cells are zero-carbon energy devices that efficiently convert hydrogen energy into electrical energy. They are an important clean energy application technology for achieving the "dual carbon" goal and are currently widely used in heavy trucks, buses, railway locomotives, spacecraft, ships, data centers and other fields. They have also become an indispensable part of the industrial decarbonization process and have shown broad market application prospects.

[0003] To expand its application range, hydrogen fuel cells need to be able to operate in all weather conditions and across temperature ranges. However, in sub-zero environments, if the heat generated by the chemical reaction during fuel cell startup is insufficient to expel water in gaseous or liquid form, it will freeze, hindering the passage of reactant gases and freezing the membrane electrode assembly (MEA), causing the electrochemical reaction to cease. In severe cases, freezing can even cause irreversible damage to the MEA. Therefore, low-temperature cold start is a major technical challenge for the widespread application of hydrogen fuel cell technology.

[0004] Currently, most fuel cell vehicles rely on auxiliary measures such as heating and insulation for low-temperature start-up. This auxiliary cold start-up increases the weight and volume of the battery system and the complexity of system operation. Therefore, it is necessary to explore technical solutions that can start the vehicle at low temperatures without external force.

[0005] Chinese patent application CN 110021768 A, "A Cold Start Control Method, Apparatus, and System for a Fuel Cell," discloses a method that outputs a mixed gas containing hydrogen and oxygen to the anode catalyst layer of a fuel cell. A portion of the hydrogen reacts catalytically with the oxygen, generating additional heat to assist the fuel cell in cold starts, thereby achieving a higher heating rate. Chinese patent application CN 118825326A, "A Cold Start Control Method and System for a Marine Fuel Cell System," discloses that during the cold start operation, the thermal management system temperature controls the operation of the PTC heater, electric heating belt, and air compressor. However, both of these patents employ auxiliary heating technology in their cold start control methods.

[0006] Chinese patent application CN114171744A, entitled "A fuel cell electrode plate and its preparation method, fuel cell stack, fuel cell system and its cold start method," describes a fuel cell electrode plate comprising an electrode plate body and a catalyst layer disposed on its surface. The catalyst layer is made of a first catalyst, which catalyzes the chemical reaction between fuel and oxidant. This invention solves the technical problems in the prior art where fuel cells utilize the exothermic reaction of fuel and oxidant in the electrocatalytic layer of the membrane electrode assembly (MEA), and where localized high temperatures, electrocatalyst particle agglomeration, and damage to the MEA easily occur during low-temperature cold starts. The invention achieves the technical effect of faster low-temperature cold start speed for fuel cells without affecting the performance of the electrocatalyst layer.

[0007] Chinese patent CN114914503A, "A Membrane Electrode for Fuel Cells and Its Preparation Method and Application," provides a membrane electrode for fuel cells, its preparation method, and its application. The membrane electrode comprises, in sequence, a cathode gas diffusion layer, a cathode microporous layer, a cathode catalyst layer, a proton exchange membrane, an anode catalyst layer, an anode microporous layer, and an anode gas diffusion layer. Both the anode and cathode catalyst layers comprise a catalyst, an ionomer, and polytetrafluoroethylene (PTFE). The difference in the mass percentage of the ionomer between the anode and cathode catalyst layers is 5-30%. This invention, by adjusting the composition and ratio of the anode and cathode in the membrane electrode within the fuel cell stack, constructs a membrane electrode structure more suitable for ultra-low temperature cold start conditions, thereby improving its ultra-low temperature cold start performance.

[0008] It is evident that current research largely focuses on optimizing fuel cell system devices and control methods, or the composition ratio of plates and membrane electrodes, in order to improve the cold start efficiency of fuel cells. There is still no research plan that addresses the water production and freezing mechanisms of fuel cells at low temperatures, designs from the perspective of catalyst microstructure, and fundamentally avoids cold start failure. Summary of the Invention

[0009] To address the problems existing in the prior art, this invention provides a carbon-supported catalyst adapted for cold start of hydrogen fuel cells and its preparation method. The cathode of a hydrogen fuel cell made using the carbon-supported catalyst of this invention is particularly suitable for the low-temperature cold start process of hydrogen fuel cells, offering advantages such as not altering the original manufacturing process of the hydrogen fuel cell cathode, and requiring no modification to the hydrogen fuel cell system equipment and control methods, thus fundamentally solving the low-temperature cold start problem of hydrogen fuel cells.

[0010] The first aspect of this invention provides super carbon black particles or aggregates thereof, wherein the super carbon black particles or aggregates thereof have any one, any two, or all three of the following characteristics:

[0011] (1) Water absorption rate is 1.5-3.0 mL / g;

[0012] (2) The internal pore volume fraction of the super carbon black particles is ≥40%; and

[0013] (3) The average diameter of the internal pores of the super carbon black particles is ≥2nm.

[0014] In one or more embodiments, the water absorption rate of the super carbon black particles or aggregates thereof is 1.75-2.75 mL / g, 1.8-2.8 mL / g, 2.0-2.8 mL / g, 2.2-2.8 mL / g, 2.5-3.0 mL / g, or 2.0-2.5 mL / g.

[0015] In one or more embodiments, the internal pore volume fraction of the super carbon black particles is 40-80% or 50-70%.

[0016] In one or more embodiments, the average diameter of the internal pores of the super carbon black particles is 2-5 nm, 2-4 nm, or 3.5-5 nm.

[0017] In one or more embodiments, the super carbon black particles comprise carbon black particles and polyethyleneimine.

[0018] In one or more embodiments, the molecular weight of the polyethyleneimine is 1200-10000, such as 2000-10000 or 5000-10000.

[0019] In one or more embodiments, the polyethyleneimine is coated on the outer surface of the carbon black particles in the form of nanoparticles.

[0020] In one or more embodiments, the polyethyleneimine content is 5-15%, such as 8-12%, based on the total mass of the super carbon black particles.

[0021] A second aspect of the present invention provides super carbon black particles or aggregates thereof, the super carbon black particles comprising carbon black particles and polyethyleneimine nanoparticles covering the surface of the carbon black particles; wherein the super carbon black particles or aggregates thereof have a water absorption rate of 2.0-3.0 mL / g, an internal pore volume fraction of 50-80%, an average internal pore diameter of 2-5 nm, a molecular weight of 1200-10000 for the polyethyleneimine, and a polyethyleneimine mass content of 5-15% based on the total mass of the super carbon black particles.

[0022] In one or more embodiments, the water absorption rate of the super carbon black particles or aggregates thereof is 1.75-2.75 mL / g, 1.8-2.8 mL / g, 2.0-2.8 mL / g, 2.2-2.8 mL / g, 2.5-3.0 mL / g, or 2.0-2.5 mL / g.

[0023] In one or more embodiments, the internal pore volume fraction of the super carbon black particles is 40-80% or 50-70%.

[0024] In one or more embodiments, the average diameter of the internal pores of the super carbon black particles is 2-5 nm, 2-4 nm, or 3.5-5 nm.

[0025] In one or more embodiments, the molecular weight of the polyethyleneimine is 2000-10000 or 5000-10000.

[0026] In one or more embodiments, the polyethyleneimine content is 8-12% by weight, based on the total mass of the super carbon black particles.

[0027] A third aspect of the present invention provides a method for preparing super carbon black particles or aggregates thereof according to any embodiment herein, characterized in that the super carbon black particles or aggregates thereof are obtained by oxidizing raw carbon black particles and soaking them in a polyethyleneimine solution.

[0028] In one or more embodiments, the raw material carbon black particles have any one or more of the following characteristics: water absorption rate of 0.5-1.2 mL / g, diameter of 10-50 nm, average internal pore diameter ≥2 nm, such as 2-5 nm, internal pore volume fraction ≥40%, such as 40-80%, and density of 0.1-0.5 g / mL.

[0029] In one or more embodiments, the oxidation treatment includes using an O2 / N2 mixture with an oxygen volume concentration of 0.5-5%, a 0.05-0.2M H2O2 solution, and / or a 0.05-0.2M HNO3 solution.

[0030] In one or more embodiments, the raw carbon black particles are heat-treated with an O2 / N2 mixture with an oxygen volume concentration of 0.5-5% at a temperature of 300-400°C, or the raw carbon black particles are dispersed in a 0.05-0.2M H2O2 solution and / or a 0.05-0.2M HNO3 solution, and optionally subjected to ultrasonic treatment for 6-12 hours during the soaking process, followed by filtration and drying.

[0031] In one or more embodiments, the polyethyleneimine aqueous solution contains 1-10% polyethyleneimine by mass.

[0032] In one or more embodiments, ultrasonic treatment is optionally applied for 6 to 12 hours during the soaking process.

[0033] In one or more embodiments, the filter cake is dried after soaking.

[0034] A fourth aspect of the present invention provides a carbon-supported catalyst, the carbon-supported catalyst comprising super carbon black particles as described in any embodiment herein and catalyst particles supported on the super carbon black particles.

[0035] In one or more embodiments, the catalyst particles are Pt-M nanoparticles, wherein M is a transition metal, such as one or more of Cu, Fe, Co and Ni.

[0036] In one or more embodiments, the atomic ratio of Pt to M in the Pt-M nanoparticles is (1-3):(0-3).

[0037] In one or more embodiments, the mass fraction of the catalyst particles deposited in the internal pores of the super carbon black particles is 5-15%, such as 5-12%, 5-10%, or 8-12%.

[0038] In one or more embodiments, the catalyst particles are loaded with ≥20% of the super carbon black particles, such as 20-60%, 25-60%, 25-55%, 29-55%, or 30-50%.

[0039] In one or more embodiments, the catalyst particles have an average diameter ≥1 nm, such as 1.0-5.5 nm, 1.5-3.5 nm, 2.0-3.5 nm or 1.5-5.0 nm.

[0040] The fifth aspect of the present invention provides a method for preparing the carbon-supported catalyst according to any embodiment herein, the method comprising the following steps: (1) mixing a colloidal solution of catalyst particles and a super carbon black particle aggregate according to any one of claims 1 to 5; (2) adjusting the pH of the resulting mixture to acidic and filtering to obtain a filter cake; (3) washing the filter cake with water to a pH of 6.5-7.5; and (4) drying the water-washed filter cake obtained in step (3) to obtain the carbon-supported catalyst.

[0041] In one or more embodiments, the method further includes the step of preparing the super carbon black particle aggregates using the method described in any embodiment of this document.

[0042] A sixth aspect of the present invention provides a hydrogen fuel cell cathode, a hydrogen fuel cell membrane electrode assembly (MEA), or a hydrogen fuel cell containing the MEA; the hydrogen fuel cell cathode includes a proton exchange membrane and a catalyst layer covering the surface of the proton exchange membrane, the catalyst layer comprising a carbon-supported catalyst as described in any embodiment herein; the hydrogen fuel cell MEA comprises a gas diffusion layer, an anode catalyst layer, a proton exchange membrane, a cathode catalyst layer, and a gas diffusion layer arranged sequentially, wherein the cathode catalyst layer comprises a carbon-supported catalyst as described in any embodiment herein.

[0043] In one or more embodiments, the amount of Pt in the carbon-supported catalyst layer is 0.05-0.4 mg / cm³. 2 .

[0044] The seventh aspect of the invention provides the use of polyethyleneimine and optional oxidants as described in any embodiment herein in the modification of carbon black particles, in the preparation of carbon-supported catalysts, or in the preparation of hydrogen fuel cells with improved low-temperature cold-start performance.

[0045] In one or more embodiments, the molecular weight of the polyethyleneimine is 1200-10000, such as 2000-10000 or 5000-10000; preferably, the oxidant is selected from an O2 / N2 mixture with an oxygen volume concentration of 0.5-5%, a 0.05-0.2M H2O2 solution, and a 0.05-0.2M HNO3 solution.

[0046] The eighth aspect of the present invention provides the use of super carbon black particles or aggregates thereof as described in any embodiment herein in the preparation of carbon-supported catalysts for low-temperature cold start of fuel cells, hydrogen fuel cell cathodes or hydrogen fuel cell membrane electrodes, or in the preparation of hydrogen fuel cells with improved low-temperature cold start performance.

[0047] The ninth aspect of the present invention provides the use of the carbon-supported catalyst as described in any embodiment herein in the preparation of a hydrogen fuel cell cathode or a hydrogen fuel cell membrane electrode for low-temperature cold start of a fuel cell, or in the preparation of a hydrogen fuel cell with improved low-temperature cold start performance.

[0048] The tenth aspect of the present invention provides the application of a hydrogen fuel cell cathode or hydrogen fuel cell membrane electrode as described in any embodiment herein in the preparation of a hydrogen fuel cell, or in improving the low-temperature cold start performance of a hydrogen fuel cell.

[0049] The beneficial effects of this invention are:

[0050] (1) Carbon black particles were transformed into super carbon black particles by treating them with a low concentration of oxidant and soaking them in a polyethyleneimine solution. On the one hand, the hydrophilicity of the surface of the super carbon black particles was significantly enhanced, and the water absorption rate was greatly increased. At the same time, the polyethyleneimine nanoparticles on the surface of the super carbon black particles could act as a barrier, so that the metal nanoparticles prepared by the colloidal method were mainly deposited on the outer surface of the super carbon black particles, while the mass fraction of metal nanoparticles entering the internal pores was 5-15%. On the other hand, the internal pore volume fraction of the super carbon black particles was higher than 40%, which could store a large amount of water. When the Pt-M nanoparticles distributed on the outer surface underwent an electrocatalytic reaction, the water generated was easily absorbed and captured in the internal pores due to the capillary effect of the internal pores and the hydrophilic effect of the polyethyleneimine nanoparticles. Especially when applied to low-temperature cold start, the liquid water stored in the internal pores is less likely to freeze due to capillary action. Therefore, it can effectively prevent the Pt-M nanoparticles on the outer surface from being severely covered by liquid water or even ice. This allows the metal nanoparticles to exert their catalytic activity efficiently at low temperatures and can also reduce or even avoid the damage to the fuel cell catalyst layer caused by freezing and the blockage of the gas transmission channel, thus successfully achieving low-temperature cold start.

[0051] (2) Using super carbon black particle aggregates as a carrier, combined with the preparation of Pt or Pt-M colloidal solutions by colloidal method, so that Pt or Pt-M nanoparticles are mainly deposited on the outer surface of super carbon black particles, while the mass fraction of Pt or Pt-M nanoparticles entering the internal pores is controlled to be 5-15%.

[0052] (3) The hydrogen fuel cell cathode made using the Pt-M / C catalyst prepared in this invention is particularly suitable for the low-temperature cold start process of hydrogen fuel cells. It has the advantages of simple catalyst preparation process, no change to the original manufacturing process of hydrogen fuel cell cathode, and no need to modify the hydrogen fuel cell system device and control method. It can fundamentally solve the low-temperature cold start problem of hydrogen fuel cells. Attached Figure Description

[0053] Figure 1 Transmission electron microscope images of the super carbon black and its Pt-Cu / C catalyst prepared in Example 1, (a) super carbon black, (b) Pt-Cu / C catalyst. Detailed Implementation

[0054] To enable those skilled in the art to understand the features and effects of this invention, the terms and expressions used herein are explained and defined in general terms below. Unless otherwise specified, all technical and scientific terms used herein have the common meaning understood by those skilled in the art regarding this invention, and in case of conflict, the definitions herein shall prevail.

[0055] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0056] In this document, the terms “contains,” “includes,” “containing,” and similar terms encompass the meanings of “basically composed of” and “composed of.” For example, when this document discloses “A contains B and C,” “A is basically composed of B and C” and “A is composed of B and C” should be considered as having been disclosed in this document.

[0057] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0058] Unless otherwise specified, percentages refer to mass percentages and proportions refer to mass ratios in this article.

[0059] In this document, when describing embodiments or examples, it should be understood that it is not intended to limit the invention to those embodiments or examples. Rather, all alternatives, modifications, and equivalents of the methods and materials described herein are covered within the scope defined by the claims.

[0060] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0061] In this invention, the water absorption rate of super carbon black particles and their aggregates can be determined according to the water absorption rate testing method in the national standard (GB / T 17671-2021), that is, the water absorption rate is calculated by measuring the mass change of the material before and after immersion in water. The average diameter and volume fraction of the internal pores of the super carbon black particles are determined by low-temperature liquid nitrogen (or argon) physical adsorption method, and the average diameter and volume fraction data in the pore size range of 1-8 nm are extracted as quantitative information of the internal pores of the super carbon black particles.

[0062] In this invention, the mass content of polyethyleneimine on carbon black particles can be estimated by measuring the nitrogen content. The nitrogen content on carbon black particles is determined by elemental analysis, for example, using a PerkinElmer elemental analyzer (EA 2400I) (the molecular formula of polyethyleneimine is (CH2CH2NH)). n(n is determined by molecular weight, and the polyethyleneimine content is determined based on the difference between the measured nitrogen content and the theoretical nitrogen content).

[0063] In this invention, the composition and content of each metal in the carbon-supported catalyst can be determined using inductively coupled plasma atomic emission spectrometry (e.g., PerkinElmer Optima 8300, USA). The size of the Pt-M nanoparticles is measured using transmission electron microscopy (e.g., JEOL JEM-3200FS, Japan). In this paper, the loading of catalyst particles on super carbon black particles refers to the mass percentage of metals in the carbon-supported catalyst (super carbon black particles + metal).

[0064] In this invention, a scanning transmission electron microscope (e.g., a Hitachi HF-5000 STEM) can be used to observe the number of Pt-M particles at the same location on the same catalyst sample in both scanning and transmission modes. The mass fraction of Pt-M nanoparticles deposited in the internal pores of the super carbon black particles can be obtained from the difference in the number of particles in the two modes.

[0065] Super carbon black particles and their aggregates

[0066] The super carbon black particles or aggregates thereof described in this article have any one, any two, or all three of the following characteristics:

[0067] (1) Water absorption rate is 1.5-3.0 mL / g;

[0068] (2) The internal pore volume fraction of the super carbon black particles is ≥40%; and

[0069] (3) The average diameter of the internal pores of the super carbon black particles is ≥2nm.

[0070] It should be understood that the super carbon black particle aggregates mentioned in this article refer to mixtures formed by mixing super carbon black particles together.

[0071] In some embodiments, the water absorption rate of the super carbon black particles or aggregates thereof described herein is 1.75-2.75 mL / g. In some embodiments, the water absorption rate of the super carbon black particles or aggregates thereof described herein is 1.8-2.8 mL / g. In some embodiments, the water absorption rate of the super carbon black particles or aggregates thereof described herein is 2.0-2.8 mL / g. In some embodiments, the water absorption rate of the super carbon black particles or aggregates thereof described herein is 2.2-2.8 mL / g. In some embodiments, the water absorption rate of the super carbon black particles or aggregates thereof described herein is 2.5-3.0 mL / g. In some embodiments, the water absorption rate of the super carbon black particles or aggregates thereof described herein is 2.0-2.5 mL / g.

[0072] In some embodiments, the internal pore volume fraction of the super carbon black particles described herein is 40-80%. In some embodiments, the internal pore volume fraction of the super carbon black particles described herein is 50-70%.

[0073] In some embodiments, the average internal pore diameter of the super carbon black particles described herein is 2-5 nm. In some embodiments, the average internal pore diameter of the super carbon black particles described herein is 2-4 nm or 3.5-5 nm.

[0074] In some embodiments, the super carbon black particles described herein comprise carbon black particles and polyethyleneimine. In this document, the molecular formula of polyethyleneimine is (CH2CH2NH). n The molecular weight (n) is determined by the molecular weight. Polyethyleneimine can be any of the various polyethyleneimine products known in the art, preferably with a molecular weight in the range of 1200-10000. The polyethyleneimine used herein is hydrophilic. In some embodiments, the molecular weight of the polyethyleneimine is 2000-10000. In some embodiments, the molecular weight of the polyethyleneimine is 5000-10000. An exemplary preferred polyethyleneimine is GBK-PEI9001 type polyethyleneimine manufactured by Gobekie Corporation.

[0075] In some embodiments, the polyethyleneimine is coated on the outer surface of the carbon black particles in the form of nanoparticles. The size of the nanoparticles is typically 5-10 nm. In some embodiments, the polyethyleneimine content is 5-15% by mass, such as 8-12%, based on the total mass of the super carbon black particles described herein.

[0076] In some embodiments, the super carbon black particles described herein comprise carbon black particles and polyethyleneimine nanoparticles covering the surface of the carbon black particles, wherein the super carbon black particles or aggregates thereof have a water absorption rate of 2.0-3.0 mL / g, an internal pore volume fraction of 50-80%, an average internal pore diameter of 2-5 nm, and the polyethyleneimine has a molecular weight of 1200-10000 and a mass content of 5-15%.

[0077] Preparation method of super carbon black particles and their aggregates

[0078] The super carbon black particles or aggregates described in this article can be obtained from conventional carbon black particles through oxidation treatment and immersion in a polyethyleneimine solution.

[0079] In some embodiments, the method for preparing the super carbon black particles or aggregates thereof described herein may include the following steps:

[0080] S1. Oxidize the raw carbon black particles using a low-concentration oxidant.

[0081] S2. The oxidized carbon black particles are soaked in a polyethyleneimine aqueous solution, subjected to ultrasonic treatment, filtered and dried to obtain the super carbon black particles.

[0082] In some embodiments, the raw carbon black granules can be purchased from commercial carbon black granules, including but not limited to the EC300J type from Ketjen Black (Japan), the Printex XE-2B type from Degussa (Germany), and the BP2000 type from Cabot (USA). In some embodiments, the water absorption rate of the raw carbon black granules is 0.5-1.2 mL / g. In some embodiments, the diameter of the raw carbon black granules is 10-50 nm. In some embodiments, the average internal pore diameter of the raw carbon black granules is ≥2 nm, such as 2-5 nm. In some embodiments, the internal pore volume fraction of the raw carbon black granules is ≥40%, such as 40-80%. In some embodiments, the density of the raw carbon black granules is 0.1-0.5 g / mL.

[0083] In step S1, the low-concentration oxidant includes, but is not limited to, an O2 / N2 mixture with an oxygen volume concentration of 0.5-5%, a 0.05-0.2M (e.g., 0.1M) H2O2 solution, and a 0.05-0.2M (e.g., 0.1M) HNO3 solution. The oxidation treatment conditions include, but are not limited to, heat treatment and solution soaking. In some embodiments, the raw carbon black particle aggregates are placed in a tube furnace, and an O2 / N2 mixture with an oxygen volume concentration of 0.5-5% (e.g., 2.5%) is introduced, and the temperature is raised to 300-400℃ (e.g., 350℃), and stabilized for 4-8 hours. In other embodiments, the raw carbon black particle aggregates are dispersed in a low-concentration oxidant solution and soaked, during which ultrasonic treatment can be performed, followed by filtration and drying. The ultrasonic treatment time can be 6-12 hours. After filtration, the filter cake can be dried in a vacuum oven. An exemplary drying condition is drying at 60-80℃ for 6-12 hours. The oxidized carbon black particles can be cooled and then soaked in a polyethyleneimine solution.

[0084] In step S2, the polyethyleneimine aqueous solution contains 1-10% polyethyleneimine by mass. It should be understood that within the mass concentration range defined herein, a higher mass fraction in the aqueous solution is permissible when the molecular weight of the polyethyleneimine used is low, and a lower mass fraction is permissible when the molecular weight of the polyethyleneimine used is high. Ultrasonic treatment can be performed for 6-12 hours during the soaking process. After soaking, the solution is filtered, and the filter cake is then dried in a vacuum oven. An exemplary drying condition is drying at 60-80°C for 6-12 hours. After drying, the super carbon black particles and their aggregates described herein are obtained.

[0085] In this invention, after oxidation treatment and immersion in polyethyleneimine solution, the surface hydrophilicity of the carbon black particles is significantly enhanced, and the water absorption rate can be greatly increased, from the original 0.5-1.2 mL / g to 1.5-3.0 mL / g, thus becoming super carbon black particles. This increased water absorption rate greatly enhances the water storage capacity of hydrogen fuel cell cathodes based on Pt- / C or Pt-M / C catalysts during low-temperature cold start-up. Simultaneously, the super carbon black particles have an average internal pore diameter of 2-5 nm and an internal pore volume fraction of 40-80%. Therefore, a large portion of the water can be stored in the internal pores of the super carbon black particles. Furthermore, due to capillary effect, the liquid water stored in the internal pores is less prone to freezing at low temperatures, thereby mitigating or even preventing the damage to the fuel cell catalyst layer and the blockage of gas transmission channels caused by freezing.

[0086] In this invention, polyethyleneimine is a hydrophilic substance with a relatively long molecular chain. Typically, polyethyleneimine molecules with a molecular weight of 1200-10000 have a size of 5-10 nm. After the oxidized carbon black particles are soaked in a polyethyleneimine solution and dried, polyethyleneimine nanoparticles mainly cover the outer surface of the carbon black particles, including the pore openings inside the carbon black particles. When the metal active component Pt or Pt-M nanoparticles are loaded, on the one hand, due to the barrier effect of polyethyleneimine nanoparticles, the Pt or Pt-M nanoparticles are mainly deposited on the outer surface of the super carbon black particles, while the mass fraction entering the internal pores is 5-15%. On the other hand, when the Pt or Pt-M nanoparticles distributed on the outer surface undergo electrocatalytic reaction to generate water, due to the capillary effect of the internal pores of the super carbon black particles and the hydrophilic effect of the polyethyleneimine nanoparticles, a large part of the water is absorbed and captured in the internal pores. This effectively avoids the situation where the Pt or Pt-M nanoparticles on the outer surface are severely covered by liquid water or even ice, allowing the catalytic activity of the metal nanoparticles to be exerted efficiently.

[0087] carbon-supported catalyst

[0088] This invention also provides a carbon-supported catalyst, comprising the super carbon black particles described in any embodiment herein and catalyst particles supported on the super carbon black particles. In this invention, the catalyst particles can be catalyst particles commonly used in hydrogen fuel cell cathodes, including but not limited to Pt-M nanoparticles, wherein M is a transition metal.

[0089] In some embodiments, the mass fraction of the catalyst particles deposited in the internal pores of the super carbon black particles is 5-15%, such as 5-12%, 5-10%, or 8-12%.

[0090] In some embodiments, the catalyst particles are loaded with ≥20% of the super carbon black particles, such as 20-60%, 25-60%, 25-55%, 29-55%, or 30-50%.

[0091] In some embodiments, the catalyst particles have an average diameter ≥1 nm, such as 1.0-5.5 nm, 1.5-3.5 nm, 2.0-3.5 nm, or 1.5-5.0 nm.

[0092] In some embodiments, the atomic ratio of Pt to M in the Pt-M nanoparticles is (1-3):(0-3). In some embodiments, M is one or more of Cu, Fe, Co, and Ni. In some embodiments, the Pt-M nanoparticles are Pt nanoparticles.

[0093] Preparation method of carbon-supported catalyst

[0094] The carbon-supported catalyst of the present invention can be prepared by loading the catalyst particles onto super carbon black particles using a colloidal method.

[0095] Specifically, the method for preparing the carbon-supported catalyst of the present invention may include the following steps:

[0096] (1) A colloidal solution of mixed catalyst particles and the super carbon black particle aggregates described herein;

[0097] (2) Adjust the pH of the resulting mixture to acidic and then filter to obtain a filter cake;

[0098] (3) Wash the filter cake with water until the pH reaches 6.5-7.5; and

[0099] (4) Dry the water-washed filter cake obtained in step (3) to obtain the carbon-supported catalyst.

[0100] In this paper, the mixing in step (1) results in the catalyst particles being loaded onto the super black particles, with some of the catalyst particles also being incorporated into the super black particle content. Mixing methods include, but are not limited to, stirring and / or ultrasonic treatment. An exemplary ultrasonic treatment time may be 6-12 hours.

[0101] In this paper, in step (1), the ratio of the mass (g) of the super carbon black particle aggregate to the volume (mL) of the colloidal solution can be 1:10 to 200, such as 1:20 to 180.

[0102] This article uses the preparation of Pt-M colloidal solution as an example to illustrate the preparation of colloidal solutions of catalyst particles. Specifically, the steps for obtaining Pt-M colloidal solution may include:

[0103] (a) Prepare an aqueous solution of a polyol containing a Pt compound, and adjust the pH of the aqueous solution to 12.5-13.5 to obtain a Pt colloidal solution; or

[0104] (b) When the catalyst particles include M, prepare aqueous solutions of polyols containing Pt and M respectively, mix the Pt-containing polyol solution with the M-containing polyol solution, and then adjust the pH of the resulting mixture to 12.5-13.5 to obtain a Pt-M colloidal solution; or

[0105] (c) When the catalyst particles include M, prepare aqueous solutions of polyols containing Pt and M respectively, and adjust the pH of both solutions to 12.5-13.5. Then mix the two solutions to prepare a Pt-M colloidal solution; or

[0106] (d) When the catalyst particles include M, prepare an aqueous solution of polyol containing Pt compound and M compound, and adjust the pH of the aqueous solution to 12.5-13.5 to obtain a Pt-M colloidal solution.

[0107] In some embodiments, the polyol may be selected from one or more of ethylene glycol, glycerol, and methylglycerol. The volume fraction of the polyol in the aqueous solution may be 80-95%.

[0108] In some embodiments, the pH of the solution is adjusted to 12.5-13.5 using an aqueous solution of a base polyol. The polyol may be as described above. In the aqueous solution of the base polyol, the base may be NaOH and / or KOH. The concentration of the base may be 0.5-1.5 mol / L. In some embodiments, the polyol used to adjust the pH of the solution in the aqueous solution of the base polyol is the same as the polyol used in the aqueous solution of the polyol for preparing the Pt-containing compound and / or M-containing compound.

[0109] In some embodiments, the Pt-containing compound may be one or more of H₂PtCl₆, PtCl₄, and Pt(NO₂)₂, or their hydrates. The concentration of the Pt compound in the solution may be 0.01-0.09 g / mL.

[0110] In some embodiments, the M-containing compound may be a variety of water-soluble salts of metal M, such as hydrochloride and / or nitrate. Exemplary M-containing compounds include, but are not limited to, one or more of CuCl2, Co(NO3)2, NiCl2, Fe(NO3)2, or their hydrates. In solutions containing the M-containing compound, the concentration of the M-containing compound may be 0.01-0.09 g / mL.

[0111] In this paper, step (2) may use an aqueous solution of acid to adjust the pH of the catalyst solution to 2.5-3.5. The acid may be one or more of HCl, HNO3, and H2CO3. The concentration of the aqueous solution of acid may be 0.5-1.5 mol / L. In some embodiments, step (2) uses an aqueous solution of HCl with a concentration of 0.5-1.5 mol / L to adjust the pH of the resulting mixture to 2.5-3.5.

[0112] In this paper, step (2) can be performed by vacuum filtration.

[0113] In this paper, step (4) can be carried out using conventional drying techniques. For example, the filter cake can be placed in a rotary evaporator and dried at 60-80°C for 12-24 hours. After drying and cooling, the carbon-supported catalyst of this invention can be obtained.

[0114] hydrogen fuel cell cathode

[0115] This invention provides a hydrogen fuel cell cathode, comprising a proton exchange membrane and a catalyst layer covering the surface of the proton exchange membrane, wherein the catalyst layer comprises the carbon-supported catalyst described herein. Preferably, the amount of Pt in the carbon-supported catalyst layer is 0.05-0.4 mg / cm³. 2 .

[0116] The hydrogen fuel cell cathode of this invention can be prepared using conventional methods for preparing hydrogen fuel cell cathodes. In some embodiments, the carbon-supported catalyst described herein is coated onto a substrate, dried to form a catalyst layer, and then the catalyst layer on the substrate is transferred to one side of the proton exchange membrane using a hot flat press to obtain the hydrogen fuel cell cathode.

[0117] In this invention, both the substrate and the proton exchange membrane can be conventional in the art. For example, the substrate is selected from PTFE, and the proton exchange membrane is purchased from GORE, Inc. in the United States.

[0118] Hydrogen fuel cell membrane electrode and hydrogen fuel cell

[0119] The present invention also provides a membrane electrode assembly for a hydrogen fuel cell, comprising a first gas diffusion layer, an anode catalyst layer, a proton exchange membrane, a cathode catalyst layer, and the first gas diffusion layer arranged sequentially; wherein the cathode catalyst layer comprises the carbon-supported catalyst described herein.

[0120] The membrane electrode of the present invention can be prepared using conventional methods for preparing hydrogen fuel cell membrane electrodes. In some embodiments, a catalyst slurry containing the carbon-supported catalyst described herein is coated onto a substrate, dried to form a catalyst layer, and then the catalyst layer on the substrate is transferred to one side of a proton exchange membrane using a hot flat press to form a cathode catalyst layer, serving as the cathode; then an anode catalyst material is coated onto the other side of the proton exchange membrane to form an anode catalyst layer, serving as the anode; a gas diffusion layer is then coated onto both catalyst layers to obtain the hydrogen fuel cell membrane electrode.

[0121] In this document, the gas diffusion layer, proton exchange membrane, and anode catalyst layer can all be gas diffusion layers, proton exchange membranes, and anode catalyst layers well known in the art. An exemplary anode catalyst layer can be formed from a Pt / C catalyst (such as a Pt / C catalyst from Premetek, USA). An exemplary gas diffusion layer is available from JNTG, Korea.

[0122] In some embodiments, the present invention provides a hydrogen fuel cell including a hydrogen fuel cell membrane electrode assembly as described in any embodiment herein. Other components of the hydrogen fuel cell are those commonly used in the art.

[0123] Methods for cold start of hydrogen fuel cells at low temperatures

[0124] The present invention also provides a method for cryogenic cold start of a hydrogen fuel cell, the method comprising the following steps:

[0125] (1) The carbon-supported catalyst described in any of the embodiments herein is used to make the cathode of a hydrogen fuel cell, and a Pt / C catalyst is used to make the anode of a hydrogen fuel cell; the cathode and anode are made into a single cell.

[0126] (2) Place the single battery in an environment of -20°C to -40°C, such as -30°C, for no less than 12 hours;

[0127] (3) Dry air is introduced into the cathode of the hydrogen fuel cell; hydrogen is introduced into the anode;

[0128] (4) At a constant current density of 0.1-0.5 A / cm 2 Startup;

[0129] (5) A successful cold start is considered when the hydrogen fuel cell runs continuously for more than 10 minutes.

[0130] In some embodiments, the catalyst particles in the carbon-supported catalyst are Pt-M nanoparticles. Preferably, the amount of Pt used is 0.05-0.4 mg / cm³. 2 .

[0131] In some implementations, a Pt / C catalyst is used to make the anode, and the Pt content can be ≤0.4 mg / cm³.2 Currently, the Pt content in commercial fuel cell catalysts is generally less than 0.4 mg / cm³. 2 .

[0132] In some implementation schemes, the low-temperature cold start performance of the battery can be tested using the national standard GB / T 43255-2023 "Test Method for Low-Temperature Cold Start Performance of Fuel Cell Electric Vehicles". For example, the test conditions are: dry air is introduced into the cathode of the hydrogen fuel cell at a stoichiometric ratio of 1.5-2.5; hydrogen is introduced into the anode at a stoichiometric ratio of 2.

[0133] The carbon-supported catalyst prepared by this invention can be used to make hydrogen fuel cell cathodes, enabling hydrogen fuel cells to achieve successful cold start at low temperatures such as -20°C to -40°C.

[0134] application

[0135] This invention provides the use of polyethyleneimine and optional oxidants, as described in any embodiment herein, in the modification of carbon black particles or in the preparation of carbon-supported catalysts. In some embodiments, the modified carbon black particles have polyethyleneimine nanoparticles on their surface that act as a barrier, causing the metal nanoparticles prepared by the colloidal method to be deposited primarily on the outer surface of the supercarbon black particles, while the mass fraction of metal nanoparticles entering the internal pores is 5-15%. In some embodiments, the polyethyleneimine has a molecular weight of 1200-10000, such as 2000-10000 or 5000-10000; preferably, the oxidant is selected from an O2 / N2 mixture with an oxygen volume concentration of 0.5-5%, a 0.05-0.2M H2O2 solution, and a 0.05-0.2M HNO3 solution.

[0136] The present invention also provides the application of the super carbon black particles or aggregates thereof described in any embodiment herein in the preparation of carbon-supported catalysts for low-temperature cold start of fuel cells, hydrogen fuel cell cathodes or hydrogen fuel cell membrane electrodes, or in the preparation of hydrogen fuel cells with improved low-temperature cold start performance.

[0137] This invention also provides the use of the carbon-supported catalyst as described herein in the preparation of hydrogen fuel cell cathodes or membrane electrodes for low-temperature cold start of fuel cells, or in the preparation of hydrogen fuel cells with improved low-temperature cold start performance.

[0138] The present invention also provides the application of the hydrogen fuel cell cathode or hydrogen fuel cell membrane electrode described in any embodiment herein in the preparation of hydrogen fuel cells, or in improving the low-temperature cold start performance of hydrogen fuel cells.

[0139] The present invention will be described below by way of specific embodiments. It should be understood that these embodiments are merely illustrative and are not intended to limit the scope of the invention. The methods, reagents, and materials used in the embodiments are conventional methods, reagents, and materials in the art, unless otherwise stated. The raw material compounds in the embodiments are all commercially available.

[0140] Example 1

[0141] Preparation of super carbon black particles

[0142] Weigh 2g of commercial carbon black granular aggregate (EC300J type), with a density of 0.3g / mL, a water absorption rate of 0.8mL / g, a particle diameter of 30nm, an average internal pore diameter of 3.5nm, and an internal pore volume fraction of 60%. Disperse it in 50mL of 0.1M H2O2 solution and soak it. Ultrasonicate it for 8 hours using a water bath ultrasonicator (model TUC-10H, Shanghai Titan Technology Co., Ltd.), then filter it. Place the filter cake in a vacuum oven (DZF-6020, Shanghai Jinghong Experimental Equipment Co., Ltd.) and dry it at 70℃ for 10 hours. Soak the cooled commercial carbon black in 50mL of 5% (w / w) polyethyleneimine aqueous solution (molecular weight of polyethyleneimine 5000), then ultrasonicate it for 8 hours. After ultrasonication, filter it. Place the filter cake in a vacuum oven and dry it at 70℃ for 10 hours. After cooling, super carbon black particle aggregates are obtained with a water absorption rate of 2.5 mL / g, an internal pore volume fraction of 65%, a polyethyleneimine mass content of 10%, and an average internal pore diameter of approximately 3.5 nm. Figure 1 (a) A transmission electron microscope image of the super carbon black prepared in Example 1.

[0143] Example 2

[0144] Preparation of super carbon black particles

[0145] 2g of commercial carbon black granular aggregate (Printex XE-2B type) with a density of 0.5g / mL, a water absorption rate of 0.5mL / g, a particle diameter of 50nm, an average internal pore diameter of 5nm, and an internal pore volume fraction of 40% was weighed. The aggregate was placed in a tube furnace (Shanghai Shiyan Electric Furnace Co., Ltd.), and an O2 / N2 mixture with an oxygen volume concentration of 2.5% was introduced. The temperature was raised to 350℃ and stabilized for 6h. The cooled commercial carbon black was then soaked in 50mL of a 2% (w / w) aqueous solution of polyethyleneimine (molecular weight 10000), followed by ultrasonic treatment for 6h. The mixture was then filtered. The filter cake was placed in a vacuum oven and dried at 60℃ for 12h. After cooling, super carbon black granular aggregates were obtained with a water absorption rate of 2.0mL / g, an internal pore volume fraction of 50%, a polyethyleneimine content of 5% (w / w), and an average internal pore diameter of approximately 5nm.

[0146] Example 3

[0147] Preparation of super carbon black particles

[0148] Weigh 2g of commercial carbon black granular aggregate (BP2000 type), with a density of 0.1g / mL, a water absorption rate of 1.2mL / g, a particle diameter of 10nm, an average internal pore diameter of 2nm, and an internal pore volume fraction of 80%. Disperse it in 50mL of 0.1M HNO3 solution and soak it. Then, ultrasonically treat it for 10h using a water bath ultrasonicator (model TUC-10H, Shanghai Titan Technology Co., Ltd.), followed by filtration. Place the filter cake in a vacuum oven (DZF-6020, Shanghai Jinghong Experimental Equipment Co., Ltd.) and dry it at 80℃ for 6h. Soak the cooled commercial carbon black in 50mL of 10% (w / w) polyethyleneimine aqueous solution (molecular weight of polyethyleneimine is 1200), followed by ultrasonic treatment for 12h. After treatment, filter it. Place the filter cake in a vacuum oven and dry it at 80℃ for 6h. After cooling, super carbon black particle aggregates are obtained with a water absorption rate of 3.0 mL / g, an internal pore volume fraction of 80%, a polyethyleneimine mass content of 15%, and an average internal pore diameter of approximately 2 nm.

[0149] Example 4

[0150] Pt-Cu / C catalyst was prepared using the super carbon black particle aggregates obtained in Example 1.

[0151] 1) Preparation of Pt-Cu colloidal solution: Weigh 0.5g of H2PtCl6 hexahydrate and add it to a 90% ethylene glycol aqueous solution to prepare a Pt concentration of 0.05g Pt / mL; weigh 0.5g of CuCl2 dihydrate and add it to a 90% ethylene glycol aqueous solution to prepare a Cu concentration of 0.05g Cu / mL; mix the two solutions to make the atomic ratio of Pt to Cu 1:3; adjust the pH of the mixture to 13.5 with a 1.0mol / L NaOH ethylene glycol aqueous solution to obtain the Pt-Cu colloidal solution.

[0152] 2) Weigh 0.5 g of the super carbon black particle aggregates prepared in Example 1 and pour them into the above Pt-Cu colloidal solution. Sonicate the mixture for 10 h using a water bath ultrasonic instrument (model TUC-10H, Shanghai Titan Technology Co., Ltd.). Then adjust the pH to 3.0 with 0.1 mol / L HCl aqueous solution. Filter the mixture and wash the filter cake with water until the pH of the filtrate is 7.0. Place the obtained filter cake in a rotary evaporator (Shanghai Xiande Experimental Instrument Co., Ltd.) and dry it at 70℃ for 18 h. After cooling, obtain the supported Pt-Cu / C catalyst. The average diameter of the Pt-Cu nanoparticles was determined to be 3.5 nm, the loading on the super carbon black particles was 44%, and the mass fraction deposited in the internal pores of the super carbon black particles was 8%. Figure 1 (b) is a transmission electron microscope image of the Pt-Cu / C catalyst prepared in Example 4.

[0153] Example 5

[0154] Pt-Ni / C catalyst was prepared using the super carbon black particle aggregates obtained in Example 2.

[0155] 1) Preparation of Pt-Ni colloidal solution: Weigh 0.5g of H2PtCl6 hexahydrate and add it to a 90% ethylene glycol aqueous solution to prepare a Pt concentration of 0.09g Pt / mL; weigh 0.076g of NiCl2 hexahydrate and add it to a 90% ethylene glycol aqueous solution to prepare a Ni concentration of 0.01g Ni / mL; mix the two solutions to make the atomic ratio of Pt to Ni 3:1; adjust the pH of the mixture to 13 with a 1.0mol / L KOH glycerol aqueous solution to obtain the Pt-Ni colloidal solution.

[0156] 2) Weigh 0.5 g of the super carbon black particle aggregates obtained in Example 2 and pour them into the above Pt-Ni colloidal solution. Sonicate the aggregates for 10 h using a water bath ultrasonic instrument (model TUC-10H, Shanghai Titan Technology Co., Ltd.). Then adjust the pH to 3.5 with 0.05 mol / L HNO3 aqueous solution. Filter the solution and wash the filter cake with water until the pH of the filtrate is 7.0. Place the resulting filter cake in a rotary evaporator (Shanghai Xiande Experimental Instrument Co., Ltd.) and dry it at 60℃ for 24 h. After cooling, obtain the supported Pt-Ni / C catalyst. The average diameter of the Pt-Ni nanoparticles was determined to be 2.0 nm, with a loading of 29% on the super carbon black particles and a mass fraction of 12% deposited in the internal pores of the super carbon black particles.

[0157] Example 6

[0158] Pt-Fe / C catalyst was prepared using the super carbon black particle aggregates obtained in Example 3.

[0159] 1) Preparation of Pt-Fe colloidal solution: Weigh 0.5g of H2PtCl6 hexahydrate and add it to an 80% glycerol aqueous solution to prepare a solution with a Pt concentration of 0.01g Pt / mL; weigh 0.17g of Fe(NO3)2 and add it to an 80% glycerol aqueous solution to prepare a solution with a Fe concentration of 0.05g Fe / mL; mix the two solutions to make the atomic ratio of Pt to Fe 1:1; adjust the pH of the mixture to 13 with a 0.5mol / L KOH glycerol aqueous solution to obtain the Pt-Fe colloidal solution.

[0160] 2) Weigh 0.2 g of the super carbon black particle aggregates obtained in Example 3 and pour them into the above Pt-Fe colloidal solution. Sonicate the mixture for 10 h using a water bath ultrasonic instrument (model TUC-10H, Shanghai Titan Technology Co., Ltd.). Then adjust the pH to 2.5 with 0.1 mol / L HNO3 aqueous solution. Filter the mixture and wash the filter cake with water until the pH of the filtrate is 7.0. Place the obtained filter cake in a rotary evaporator (Shanghai Xiande Experimental Instrument Co., Ltd.) and dry it at 80℃ for 12 h. After cooling, obtain the supported Pt-Fe / C catalyst. The average diameter of the Pt-Fe nanoparticles was determined to be 5.0 nm, the loading on the super carbon black particles was 55%, and the mass fraction deposited in the internal pores of the super carbon black particles was 5%.

[0161] Example 7

[0162] Pt / C catalyst prepared using the super carbon black particle aggregates obtained in Example 3

[0163] 1) Preparation of Pt colloidal solution: Weigh 0.5g of H2PtCl6 hexahydrate, add 95% ethylene glycol aqueous solution to prepare a solution with a Pt concentration of 0.02g Pt / mL, adjust the pH of the solution to 12.5 with 1.5mol / L NaOH ethylene glycol aqueous solution to obtain Pt colloidal solution.

[0164] 2) Weigh 0.2 g of the super carbon black particle aggregates obtained in Example 3 and pour them into the above Pt colloidal solution. Sonicate the mixture for 8 h using a water bath ultrasonic instrument (model TUC-10H, Shanghai Titan Technology Co., Ltd.). Then adjust the pH to 3.0 with 0.1 mol / L HCl aqueous solution. Filter the mixture and wash the filter cake with water until the pH of the filtrate is 6.5. Place the obtained filter cake in a rotary evaporator (Shanghai Xiande Experimental Instrument Co., Ltd.) and dry it at 80℃ for 12 h. After cooling, obtain the supported Pt / C catalyst. The average diameter of the Pt nanoparticles was determined to be 1.5 nm, the loading on the super carbon black particles was 46%, and the mass fraction deposited in the internal pores of the super carbon black particles was 10%.

[0165] Comparative Example 1

[0166] The only difference between Comparative Example 1 and Example 7 is that the super carbon black particle aggregates were replaced with commercial carbon black particle aggregates (BP2000 type), and the rest of the preparation steps were the same as in Example 7.

[0167] The prepared Pt / C catalyst was measured to have an average Pt nanoparticle diameter of 5.6 nm, a loading of 38% on commercial carbon black particles, and a mass fraction of 2% deposited in the internal pores of the carbon black particles.

[0168] Comparative Example 2

[0169] 1) Partial Modification of Commercial Carbon Black Particle Aggregates (without Polyethyleneimine Aqueous Solution Soaking): Weigh 2g of commercial carbon black particle aggregates (BP2000 type), with a density of 0.1g / mL, a water absorption rate of 1.2mL / g, a particle diameter of 10nm, an average internal pore diameter of 2nm, and an internal pore volume fraction of 80%. Disperse the aggregates in 50mL of 0.1M HNO3 solution and soak them. Sonicate the aggregates for 10h using a water bath ultrasonicator (model TUC-10H, Shanghai Titan Technology Co., Ltd.), then filter. Place the filter cake in a vacuum oven (DZF-6020, Shanghai Jinghong Experimental Equipment Co., Ltd.) and dry it at 80℃ for 6h. After cooling, partially modified commercial carbon black particle aggregates are obtained, with a water absorption rate of 1.4mL / g and an internal pore volume fraction of 80%.

[0170] 2) Preparation of Pt colloidal solution and Pt / C catalyst: The preparation process of the Pt colloidal solution was the same as in Example 7. 0.2 g of partially modified commercial carbon black particle aggregates were weighed and poured into the above Pt colloidal solution. The mixture was ultrasonically treated for 8 h using a water bath ultrasonic bath (model TUC-10H, Shanghai Titan Technology Co., Ltd.). The pH was then adjusted to 3.0 with 0.1 mol / L HCl aqueous solution. The mixture was then filtered, and the filter cake was washed with water until the pH of the filtrate reached 6.5. The resulting filter cake was placed in a rotary evaporator (Shanghai Xiande Experimental Instrument Co., Ltd.) and dried at 80 °C for 12 h. After cooling, the supported Pt / C catalyst was obtained. The average diameter of the Pt nanoparticles was determined to be 2.0 nm, the loading on the partially modified commercial carbon black particles was 42%, and the mass fraction deposited in the internal pores of the carbon black particles was 30%.

[0171] Comparative Example 3

[0172] 1) Partial Modification of Commercial Carbon Black Particle Aggregates (without low-concentration oxidant treatment): Weigh 2g of commercial carbon black particle aggregates (BP2000 type), with a density of 0.1g / mL, a water absorption rate of 1.2mL / g, a particle diameter of 10nm, an average internal pore diameter of 2nm, and an internal pore volume fraction of 80%. Soak the aggregates in 50mL of a 10% (w / w) aqueous solution of polyethyleneimine (molecular weight 300), followed by ultrasonic treatment for 12h. Filter the solution afterward. Place the filter cake in a vacuum oven and dry it at 80℃ for 6h. After cooling, partially modified commercial carbon black particle aggregates are obtained, with a water absorption rate of 1.4mL / g, an internal pore volume fraction of 80%, and a polyethyleneimine content of 6%.

[0173] 2) Preparation of Pt colloidal solution and Pt / C catalyst: The preparation process of the Pt colloidal solution was the same as in Example 7. 0.2 g of partially modified commercial carbon black particle aggregates were weighed and poured into the above Pt colloidal solution. The mixture was ultrasonically treated for 8 h using a water bath ultrasonic bath (model TUC-10H, Shanghai Titan Technology Co., Ltd.). The pH was then adjusted to 3.0 with 0.1 mol / L HCl aqueous solution. The mixture was then filtered, and the filter cake was washed with water until the pH of the filtrate reached 6.5. The resulting filter cake was placed in a rotary evaporator (Shanghai Xiande Experimental Instrument Co., Ltd.) and dried at 80 °C for 12 h. After cooling, the supported Pt / C catalyst was obtained. The average diameter of the Pt nanoparticles was determined to be 2.5 nm, the loading on the partially modified commercial carbon black particles was 45%, and the mass fraction deposited in the internal pores of the carbon black particles was 3%.

[0174] Comparative Example 4

[0175] 1) Prepare Pt solution: Weigh 0.5g of H2PtCl6 hexahydrate and add it to a 95% ethylene glycol aqueous solution to prepare a Pt concentration of 0.02g Pt / mL.

[0176] 2) Weigh 0.2 g of the super carbon black particle aggregates prepared in Example 3 and pour them into the above Pt solution. Sonicate the aggregates using a water bath ultrasonic bath (model TUC-10H, Shanghai Titan Technology Co., Ltd.) for 8 hours. Then filter the mixture and wash the filter cake with water until the pH of the filtrate reaches 6.5. Place the resulting filter cake in a rotary evaporator (Shanghai Xiande Experimental Instrument Co., Ltd.) and dry it at 80℃ for 12 hours. After cooling, a supported Pt / C catalyst is obtained. The average diameter of the Pt nanoparticles was determined to be 1.5 nm, with a loading of 18% on the partially modified commercial carbon black particles and a mass fraction of 42% deposited within the internal pores of the carbon black particles.

[0177] Comparative Example 5

[0178] 1) Weigh 2g of commercial carbon black granular aggregate (BP2000 type), with a density of 0.1g / mL, a water absorption rate of 1.2mL / g, a carbon black particle diameter of 10nm, an average internal pore diameter of 2nm, and an internal pore volume fraction of 80%. Disperse it in 50mL of 0.1M HNO3 solution and soak it. Ultrasonicate it for 10h using a water bath ultrasonicator (model TUC-10H, Shanghai Titan Technology Co., Ltd.), then filter it. Place the filter cake in a vacuum oven (DZF-6020, Shanghai Jinghong Experimental Equipment Co., Ltd.) and dry it at 80℃ for 6h. Soak the cooled commercial carbon black in 50mL of 10% (w / w) polyethyleneimine aqueous solution (molecular weight of polyethyleneimine is 600), then ultrasonicate it for 12h. After ultrasonication, filter it. Place the filter cake in a vacuum oven and dry it at 80℃ for 6h. After cooling, super carbon black granular aggregates are obtained, with a water absorption rate of 3.0 mL / g, an internal pore volume fraction of 80%, and a polyethyleneimine mass content of 11%.

[0179] 2) Preparation of Pt colloidal solution: Weigh 0.5g of H2PtCl6 hexahydrate, add 95% ethylene glycol aqueous solution to prepare a solution with a Pt concentration of 0.02g Pt / mL, adjust the pH of the solution to 12.5 with 1.5mol / L NaOH ethylene glycol aqueous solution to obtain Pt colloidal solution.

[0180] 3) Weigh 0.2 g of super carbon black particle aggregates and pour them into the above Pt colloidal solution. Sonicate the solution for 8 h using a water bath ultrasonic instrument (model TUC-10H, Shanghai Titan Technology Co., Ltd.). Then adjust the pH to 3.0 with 0.1 mol / L HCl aqueous solution. Filter the solution and wash the filter cake with water until the pH of the filtrate is 6.5. Place the obtained filter cake in a rotary evaporator (Shanghai Xiande Experimental Instrument Co., Ltd.) and dry it at 80℃ for 12 h. After cooling, the supported Pt / C catalyst is obtained. The average diameter of the Pt nanoparticles was determined to be 1.2 nm, the loading on the super carbon black particles was 48%, and the mass fraction deposited in the internal pores of the super carbon black particles was 17%.

[0181] Comparative Example 6

[0182] 2g of commercial carbon black granular aggregate (BP2000 type) with a density of 0.1g / mL, a water absorption rate of 1.2mL / g, a particle diameter of 10nm, an average internal pore diameter of 2nm, and an internal pore volume fraction of 80% was weighed. This aggregate was dispersed in 50mL of 0.1M HNO3 solution and soaked in it. The mixture was then ultrasonically treated for 10h using a water bath ultrasonicator (model TUC-10H, Shanghai Titan Technology Co., Ltd.), followed by filtration. The filter cake was placed in a vacuum oven (DZF-6020, Shanghai Jinghong Experimental Equipment Co., Ltd.) and dried at 80℃ for 6h. The cooled commercial carbon black was then soaked in 50mL of a 15% (w / w) aqueous solution of polyethyleneimine (molecular weight 1200), followed by ultrasonic treatment for 12h. The mixture was then filtered, and the filter cake was placed in a vacuum oven and dried at 80℃ for 6h. The resulting sample had a water absorption rate >3.0mL / g, but was viscous and unsuitable for further use.

[0183] Comparative Example 7

[0184] 1) Weigh 2g of commercial carbon black granular aggregate (Vulcan XC-72R type, Cabot Corporation, USA), with a density of 0.1g / mL, a water absorption rate of 0.2mL / g, a carbon black particle diameter of 30nm, an average internal pore diameter of 3.6nm, and an internal pore volume fraction of 25%. Place it in a tube furnace (Shanghai Shiyan Electric Furnace Co., Ltd.), introduce an O2 / N2 mixture with an oxygen volume concentration of 2.5%, heat to 350℃, and stabilize for 6h. After cooling, soak the obtained commercial carbon black in 50mL of a 2% (w / w) aqueous solution of polyethyleneimine (molecular weight 10000), then sonicate for 6h, and filter. Place the filter cake in a vacuum oven and dry at 60℃ for 12h. After cooling, the modified carbon black granular aggregate is obtained, with a water absorption rate of 0.9mL / g, an internal pore volume fraction of 30%, and a polyethyleneimine content of 5%.

[0185] 2) Preparation of Pt-Ni colloidal solution: Weigh 0.5g of H2PtCl6 hexahydrate and add it to a 90% (v / v) ethylene glycol aqueous solution to prepare a solution with a Pt concentration of 0.09g Pt / mL; weigh 0.076g of NiCl2 hexahydrate and add it to a 90% (v / v) ethylene glycol aqueous solution to prepare a solution with a Ni concentration of 0.01g Ni / mL; mix the two solutions to make the atomic ratio of Pt to Ni 3:1; adjust the pH of the mixture to 13 with a 1.0mol / L KOH glycerol aqueous solution to obtain the Pt-Ni colloidal solution.

[0186] 3) Weigh 0.5g of the modified carbon black particle aggregate and pour it into the above Pt-Ni colloidal solution. Sonicate the mixture for 10h using a water bath ultrasonic instrument (model TUC-10H, Shanghai Titan Technology Co., Ltd.). Then adjust the pH to 3.5 with 0.05mol / L HNO3 aqueous solution. Filter the mixture and wash the filter cake with water until the pH of the filtrate reaches 7.0. Place the obtained filter cake in a rotary evaporator (Shanghai Xiande Experimental Instrument Co., Ltd.) and dry it at 60℃ for 24h. After cooling, the supported Pt-Ni / C catalyst is obtained. The average diameter of the Pt-Ni nanoparticles was determined to be 2.5nm, with a loading of 26% on the modified carbon black particles and a mass fraction of 13% deposited in the internal pores of the modified carbon black particles.

[0187] Test case

[0188] 1. Fabrication of hydrogen fuel cell cathode and membrane electrode assembly: First, the Pt-M / C catalysts prepared in the aforementioned examples and comparative examples are used according to the target Pt loading (0.05-0.4 mg / cm³). 2 The required mass was weighed and dispersed in a pre-prepared solvent, which consisted of a 3:1 volume ratio of n-propanol and ultrapure water. Nafion solution was then added to adjust the Nafion-to-C support mass ratio to 0.8. After thorough stirring, the mixture was ultrasonically dispersed to obtain a uniform and stable catalyst slurry. The prepared catalyst slurry was coated onto a PTFE substrate using a wire rod coating method and dried at 65°C for 10 minutes. The proton exchange membrane was then cut to the specified size using a cutter. The catalyst layer on the PTFE was transferred to one side of the proton exchange membrane using a hot flatbed press, thus obtaining the cathode of the fuel cell. The other side was coated with a commercial Pt / C catalyst (0.4 mg / cm³). 2 The anode was a gas diffusion layer (Premetek, USA). Finally, gas diffusion layers were applied to both sides to form a complete membrane electrode assembly. The gas diffusion layer was purchased from JNTG, South Korea, with a thickness of 250 μm, and the proton exchange membrane was purchased from GORE, USA, with a thickness of 8 μm.

[0189] 2. Fuel Cell Low-Temperature Cold Start Test: Before the test, the prepared membrane electrode assembly (MEA) is installed into the single-cell test fixture. During assembly, sealing rings are placed on both sides of the MEA to ensure the airtightness of the gas channels and prevent leakage from affecting test accuracy. The entire single cell is then placed in a constant-temperature cold chamber (-20~-40℃) for at least 12 hours. It is then installed on the FT-100W PEM single-cell test system (China Byte Measurement & Control Technology Co., Ltd.) and the low-temperature cold start performance test is conducted according to the national standard GB / T43255-2023 "Test Method for Low-Temperature Cold Start Performance of Fuel Cell Electric Vehicles". The test conditions are: dry air is introduced into the hydrogen fuel cell cathode at a stoichiometric ratio of 1.5-2.5; hydrogen is introduced into the anode at a stoichiometric ratio of 2. A constant current density of 0.1-0.5 A / cm³ is maintained. 2 The following steps will be executed to start the process.

[0190] The results of continuous operation time, temperature at the end of operation, and voltage during cold start testing for Examples 4-7 and Comparative Examples 1-7 are shown in Table 1.

[0191] Table 1: Cold Start Test Results

[0192] Case Cold start duration (min) Temperature at the end (°C) Voltage at the end (V) Example 4 12 52 0.36 Example 5 12 65 0.41 Example 6 12 39 0.53 Example 7 12 48 0.40 Comparative Example 1 3.1 -16 0.08 Comparative Example 2 5.2 -10 0.17 Comparative Example 3 4.6 -8 0.12 Comparative Example 4 6.0 -3 0.21 Comparative Example 5 8.0 -2 0.23 Comparative Example 7 2.3 -19 0.1

[0193] The results showed that the single cells made from the cathode catalysts prepared in Examples 4-7 could run continuously for more than 10 minutes, and the temperature at the end was above 0°C, even reaching a relatively high temperature. The output voltage was also generally above 0.4V, indicating that the cells could operate stably. In contrast, the cold start tests of Comparative Examples 1-7 did not meet the success criteria, i.e., they shut down after a period of time, and the temperature at the end was below 0°C, indicating that the cold start of the cells failed. The test results fully demonstrate the excellent performance of the catalyst provided by this invention, and its particular suitability for the low-temperature cold start process of hydrogen fuel cells.

[0194] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A super carbon black particle or aggregate thereof, characterized in that, The super carbon black particles or aggregates thereof have any one, any two, or all three of the following characteristics: (1) Water absorption rate is 1.5-3.0 mL / g; (2) The internal pore volume fraction of the super carbon black particles is ≥40%; and (3) The average diameter of the internal pores of the super carbon black particles is ≥2nm.

2. The super carbon black particles or aggregates thereof as described in claim 1, characterized in that: The water absorption rate of the super carbon black particles or aggregates thereof is 1.75-2.75 mL / g, 1.8-2.8 mL / g, 2.0-2.8 mL / g, 2.2-2.8 mL / g, 2.5-3.0 mL / g, or 2.0-2.5 mL / g; The internal pore volume fraction of the super carbon black particles is 40-80% or 50-70%; The average diameter of the internal pores of the super carbon black particles is 2-5 nm, 2-4 nm, or 3.5-5 nm.

3. The super carbon black particles or aggregates thereof as described in claim 1, characterized in that, The super carbon black granules comprise carbon black granules and polyethyleneimine; Preferably, the molecular weight of the polyethyleneimine is 1200-10000, such as 2000-10000 or 5000-10000. Preferably, the polyethyleneimine is coated on the outer surface of the carbon black particles in the form of nanoparticles; Preferably, the polyethyleneimine content is 5-15%, such as 8-12%, based on the total mass of the super carbon black particles.

4. A super carbon black particle or aggregate thereof, characterized in that, The super carbon black particles comprise carbon black particles and polyethyleneimine nanoparticles covering the surface of the carbon black particles; wherein the water absorption rate of the super carbon black particles or their aggregates is 2.0-3.0 mL / g, the internal pore volume fraction of the super carbon black particles is 50-80%, the average internal pore diameter of the super carbon black particles is 2-5 nm, the molecular weight of the polyethyleneimine is 1200-10000, and the mass content of the polyethyleneimine is 5-15% based on the total mass of the super carbon black particles.

5. The super carbon black particles or aggregates thereof as described in claim 4, characterized in that: The water absorption rate of the super carbon black particles or aggregates thereof is 1.75-2.75 mL / g, 1.8-2.8 mL / g, 2.0-2.8 mL / g, 2.2-2.8 mL / g, 2.5-3.0 mL / g, or 2.0-2.5 mL / g; The internal pore volume fraction of the super carbon black particles is 40-80% or 50-70%; The average diameter of the internal pores of the super carbon black particles is 2-5 nm, 2-4 nm, or 3.5-5 nm; The molecular weight of the polyethyleneimine is 2000-10000 or 5000-10000; and / or The polyethyleneimine content is 8-12% based on the total mass of the super carbon black particles.

6. A method for preparing super carbon black particles or aggregates thereof as described in any one of claims 1 to 5, characterized in that, The super carbon black particles or their aggregates are obtained by oxidation treatment and polyethyleneimine solution soaking treatment of raw carbon black particles. Preferably, the raw material carbon black particles have any one or more of the following characteristics: water absorption rate of 0.5-1.2 mL / g, diameter of 10-50 nm, average internal pore diameter ≥2 nm, such as 2-5 nm, internal pore volume fraction ≥40%, such as 40-80%, and density of 0.1-0.5 g / mL; Preferably, the oxidation treatment includes oxidation using an O2 / N2 mixture with an oxygen volume concentration of 0.5-5%, a 0.05-0.2M H2O2 solution, and / or a 0.05-0.2M HNO3 solution; preferably, the raw carbon black particles are heat-treated with an O2 / N2 mixture with an oxygen volume concentration of 0.5-5% at a temperature of 300-400°C, or the raw carbon black particles are dispersed in a 0.05-0.2M H2O2 solution and / or a 0.05-0.2M HNO3 solution, and optionally subjected to ultrasonic treatment for 6-12 hours during the soaking process, followed by filtration and drying; Preferably, the polyethyleneimine aqueous solution contains 1-10% polyethyleneimine by mass; preferably, ultrasonic treatment is optionally applied for 6-12 hours during the soaking process; preferably, the filter cake is dried after soaking.

7. A carbon-supported catalyst, characterized in that, The carbon-supported catalyst includes super carbon black particles as described in any one of claims 1 to 5 and catalyst particles supported on the super carbon black particles. Preferably, the catalyst particles are Pt-M nanoparticles, wherein M is a transition metal, such as one or more of Cu, Fe, Co and Ni; more preferably, the atomic ratio of Pt to M in the Pt-M nanoparticles is (1-3):(0-3). Preferably, the mass fraction of the catalyst particles deposited in the internal pores of the super carbon black particles is 5-15%, such as 5-12%, 5-10%, or 8-12%. Preferably, the catalyst particles are loaded onto the super carbon black particles at a rate of ≥20%, such as 20-60%, 25-60%, 25-55%, 29-55%, or 30-50%. Preferably, the average diameter of the catalyst particles is ≥1 nm, such as 1.0-5.5 nm, 1.5-3.5 nm, 2.0-3.5 nm or 1.5-5.0 nm.

8. A method for preparing the carbon-supported catalyst as described in claim 7, characterized in that, The method includes the following steps: (1) A colloidal solution of mixed catalyst particles and super carbon black particle aggregates according to any one of claims 1 to 5; (2) Adjust the pH of the resulting mixture to acidic and then filter to obtain a filter cake; (3) Wash the filter cake with water until the pH reaches 6.5-7.5; and (4) Dry the water-washed filter cake obtained in step (3) to obtain the carbon-supported catalyst; Preferably, the method further includes the step of preparing the super carbon black particle aggregate using the method of claim 6.

9. A hydrogen fuel cell cathode, a hydrogen fuel cell membrane electrode assembly, or a hydrogen fuel cell containing the hydrogen fuel cell membrane electrode assembly, characterized in that: The hydrogen fuel cell cathode includes a proton exchange membrane and a catalyst layer covering the surface of the proton exchange membrane, wherein the catalyst layer comprises the carbon-supported catalyst as described in claim 7; preferably, the amount of Pt in the carbon-supported catalyst layer is 0.05-0.4 mg / cm³. 2 ; The hydrogen fuel cell membrane electrode comprises a gas diffusion layer, an anode catalyst layer, a proton exchange membrane, a cathode catalyst layer, and a gas diffusion layer arranged sequentially, wherein the cathode catalyst layer comprises the carbon-supported catalyst as described in claim 7.

10. Selected from the following applications: (1) The application of polyethyleneimine and optional oxidant in the modification of carbon black particles, or in the preparation of carbon-supported catalysts, or in the preparation of hydrogen fuel cells with improved low-temperature cold-start performance; preferably, the molecular weight of the polyethyleneimine is 1200-10000, such as 2000-10000 or 5000-10000; preferably, the oxidant is selected from O2 / N2 mixture with an oxygen volume concentration of 0.5-5%, 0.05-0.2M H2O2 solution and 0.05-0.2M HNO3 solution; (2) The application of the super carbon black particles or aggregates of any one of claims 1 to 5 in the preparation of carbon-supported catalysts for low-temperature cold start of fuel cells, hydrogen fuel cell cathodes or hydrogen fuel cell membrane electrodes, or in the preparation of hydrogen fuel cells with improved low-temperature cold start performance. (3) The application of the carbon-supported catalyst of claim 7 in the preparation of hydrogen fuel cell cathode or hydrogen fuel cell membrane electrode for low-temperature cold start of fuel cells, or in the preparation of hydrogen fuel cells with improved low-temperature cold start performance. (4) The application of the hydrogen fuel cell cathode or hydrogen fuel cell membrane electrode according to claim 9 in the preparation of hydrogen fuel cells, or in improving the low-temperature cold start performance of hydrogen fuel cells.

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