A catalyst slurry for fuel cells and its preparation and use

Abstract

A catalyst slurry for fuel cells, its preparation, and its application belong to the field of proton exchange membrane fuel cell technology. The catalyst slurry comprises: molecular carbon electronic materials, a platinum-based catalyst, a perfluorosulfonic acid ionomer, water, and an alcohol solvent. The molecular carbon electronic material forms a permeable interfacial layer on the surface of the platinum-based catalyst nanoparticles. On the one hand, it acts as an electron buffer to regulate the electronic structure of platinum active sites to optimize the adsorption of oxygen reduction intermediates; on the other hand, it acts as a geometric shielding layer to weaken the adsorption poisoning of the platinum surface by the ionomer sulfonic acid groups and reduce interfacial oxygen transport resistance. Thus, it simultaneously improves the activity, durability, and mass transfer performance of the membrane electrode assembly without hindering gas diffusion. The molecular carbon-co-platinum-based catalyst of this invention can be used to prepare cathode catalyst layers, membrane electrode assemblies, and fuel cell stacks, showing promising application prospects of reducing the amount of precious metals used and achieving high power density and long-life operation.

Description

Technical Field

[0001] This invention relates to the field of proton exchange membrane fuel cells (PEMFCs), and more particularly to a platinum-based catalyst slurry that achieves electronic structure regulation and interface shielding through molecular carbon electronic materials, its preparation method, and its application in cathode catalyst layers, membrane electrode assemblies, and fuel cell stacks. Background Technology

[0002] A fuel cell is an energy conversion device that directly converts the chemical energy of fuel into electrical energy. It boasts advantages such as high energy efficiency, low emissions, and quiet operation, making it a crucial technological approach for achieving cleaner energy and carbon reduction in the transportation sector. In particular, proton exchange membrane fuel cells (PEMFCs), with their advantages of rapid low-temperature start-up, high power density, and high system integration, show great promise in applications such as heavy-duty transportation power, distributed power generation, and backup power. A PEMFC typically consists of a proton exchange membrane, anode and cathode catalyst layers, a gas diffusion layer, and bipolar plates. The catalyst layer, located at the interface between the electrode and the proton exchange membrane, is the core region where electrochemical reactions occur, responsible for the anodic oxidation-reduction reaction and the cathode oxygen reduction reaction (ORR). Its performance directly determines the efficiency and output capacity of the fuel cell.

[0003] Currently, platinum (Pt) and its alloy catalysts remain the most mature and reliable catalytic material system for ORR at PEMFC cathodes due to their excellent electrochemical activity and stability in acidic environments. In practical MEAs, Pt-based catalysts not only need to provide sufficient intrinsic activity but also need to maintain high utilization and long-term stability under complex ionomer / pore structure / water management conditions. However, due to the slow ORR kinetics, complex mass transfer pathways within the catalyst layer, and the reduction of effective active sites caused by ionomer coverage, existing PEMFCs often rely on high Pt loadings to meet power density requirements, thus significantly increasing system costs; at the same time, the scarcity of Pt resources further limits its large-scale commercial application.

[0004] In addition, Pt-based catalysts face several key bottlenecks under actual operating conditions: On the one hand, oxygen and proton transport within the three-phase interface of the catalyst layer is limited, especially under low Pt loading and high current density conditions, which makes it easier for concentration polarization to occur, making it difficult to convert intrinsic activity into stack power output; on the other hand, sulfonic acid groups in perfluorosulfonic acid ionomers (such as Nafion) are prone to specific adsorption on the Pt surface and cover active sites, causing "ionomer poisoning", which further reduces catalyst utilization and increases oxygen mass transfer resistance; at the same time, under high potential fluctuation conditions such as start-up, shutdown and load cycling, Pt and Pt alloy nanoparticles are prone to dissolution, migration and agglomeration, resulting in the decay of electrochemical active area, which in turn causes continuous degradation of fuel cell performance and insufficient lifespan.

[0005] Therefore, there is an urgent need to propose a new catalyst and interface design scheme that can simultaneously achieve Pt electronic structure regulation, suppress ionomer poisoning, and improve nanoparticle structural stability without sacrificing mass transfer, so as to meet the practical application requirements of PEMFC stacks with low noble metal content, high power density, and long lifespan. Summary of the Invention

[0006] The purpose of this invention is to solve the above-mentioned problems in the prior art and provide a catalyst slurry for fuel cells, its preparation and application. By introducing molecular carbon electronic materials to construct a permeable interface layer of "electronic buffer + geometric shield", the activity, durability and mass transfer performance of membrane electrode are improved at the same time, while reducing the amount of precious metals used. It is suitable for single cell and stack-level applications.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A catalyst slurry for fuel cells comprises: a molecular carbon electronic material, a platinum-based catalyst, a perfluorosulfonic acid ionomer, water, and an alcohol solvent; wherein the molecular carbon electronic material is a carbon material with electron acceptor properties, selected from at least one of fullerenes and graphene; the fullerene includes C 50 C 60 C 70 C 76 C 78 C 84 C 90 At least one of them.

[0009] The platinum-based catalyst includes at least one of Pt / C, PtCo / C, PtNi / C, PtFe / C, and PtCu / C; the platinum content in the platinum-based catalyst is 10wt% to 70wt% by mass.

[0010] The perfluorosulfonic acid ionomer is selected from at least one of Nafion, Aquivion, Flemion, or Aciplex; the alcohol solvent is selected from at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol, or tert-butanol.

[0011] A method for preparing the catalyst slurry includes the following steps:

[0012] 1) Molecular carbon electronic materials and perfluorosulfonic acid ionomers are mixed and dispersed in an alcohol solvent to obtain a pre-dispersion;

[0013] 2) The platinum-based catalyst is added to the pre-dispersion liquid, and then water and alcohol solvent are added and mixed to disperse the catalyst slurry.

[0014] The dispersion is performed by ultrasonic dispersion and / or high-speed shear dispersion; the ultrasonic power is 20-500 W, and the dispersion time is 10-120 min.

[0015] In step 1), the mass ratio of the molecular carbon electronic material, perfluorosulfonic acid ionomer, and alcohol solvent is 1:(1-800):(50-2000); in step 2), the mass ratio of platinum-based catalyst, water, alcohol solvent, and pre-dispersion liquid is 1:(10-200):(20-300):(0.5-20); and the mass ratio of the molecular carbon electronic material to the platinum-based catalyst is 1:(0.5-100).

[0016] The application of the catalyst slurry in the preparation of the cathode catalyst layer of a proton exchange membrane fuel cell.

[0017] A cathode catalyst layer is obtained by spraying or scraping the catalyst slurry described in this invention to form a film.

[0018] A membrane electrode assembly includes a proton exchange membrane and a cathode catalyst layer and an anode catalyst layer located on both sides thereon; wherein the cathode catalyst layer is the cathode catalyst layer described in this invention.

[0019] A single cell or stack of fuel cells includes the membrane electrode assembly described in this invention.

[0020] Compared with the prior art, the beneficial effects achieved by the technical solution of this invention are:

[0021] 1. This invention introduces graphene and fullerene-like molecular carbon electronic materials to construct a synergistic interface of "molecular electronic buffer and geometric shield" on the surface of platinum or platinum alloy catalysts. This interface can act as an electron acceptor to regulate the adsorption energy of Pt d state and oxygen intermediate, thereby improving the kinetics and catalytic activity of oxygen reduction reaction.

[0022] 2. The permeable molecular shielding layer formed by graphene and fullerene in this invention can weaken the specific adsorption of sulfonic acid groups on Pt active sites in perfluorosulfonic acid ionomers, reduce ionomer poisoning, improve catalyst utilization, and simultaneously reduce oxygen mass transfer resistance.

[0023] 3. The interfacial interaction between graphene, fullerene and metal nanoparticles in this invention can inhibit deactivation processes such as particle migration, aggregation and dissolution, and significantly improve the durability of the catalyst layer; moreover, the slurry preparation method of this invention is simple and easy to scale up, and is suitable for single cells with low precious metal loads and kW-level stacks, with good universality and industrial application prospects. Attached Figure Description

[0024] Figure 1 The C-containing sample provided in Example 1 70 Transmission electron microscopy image of fullerene-modified Pt / C catalyst.

[0025] Figure 2 The image shows a transmission electron microscope image of the PtCo catalyst provided in Example 13.

[0026] Figure 3 A comparison of polarization and power density curves measured for membrane electrode assemblies containing catalyst layers formed from catalyst slurries of Example 1 and Comparative Example 1.

[0027] Figure 4 This is a comparison graph of the polarization curves of the membrane electrode assemblies containing the catalysts of Example 1 and Comparative Example 1 for fuel cells.

[0028] Figure 5 This is a comparison chart of the mass activity measured for fuel cells containing the catalyst membrane electrode of Example 1 and Comparative Example 1.

[0029] Figure 6 This is a comparison graph showing the stability of the catalysts in Example 1 and Comparative Example 1.

[0030] Figure 7 This is a comparison of RDE polarization curves for catalysts from Examples 1, 4, 5, and Comparative Example 1.

[0031] Figure 8 This is a comparison chart of the mass activity of the catalysts in Examples 1, 4, 5 and Comparative Example 1.

[0032] Figure 9 The graph shows a comparison of the polarization curves and power density curves of fuel cells containing catalysts from Examples 1, 3, 4 and Comparative Example 1.

[0033] Figure 10 The graph shows a comparison of the polarization curves and power density curves of fuel cells containing catalysts from Examples 6, 9, and 10.

[0034] Figure 11 The graph shows a comparison of the polarization curves and power density curves of fuel cells containing the catalysts of Example 13 and Comparative Example 2.

[0035] Figure 12 The membrane electrode of the fuel cell, formed by the catalyst layer of the catalyst slurry in Example 1 and Comparative Example 1, was tested at 5A cm⁻¹. -2 The following is a comparison of electrochemical hydrogen and oxygen impedance.

[0036] Figure 13 The membrane electrode of the fuel cell, formed by the catalyst layer of the catalyst slurry in Example 1 and Comparative Example 1, was tested at 5A cm⁻¹. -2 The following is a comparison of electrochemical hydrogen-air impedance.

[0037] Figure 14 The image shown is the in-situ infrared spectrum of Comparative Example 1.

[0038] Figure 15This is the in-situ infrared spectrum of Example 1.

[0039] Figure 16 This is a diagram of the fuel cell stack composed of the catalyst from Example 13.

[0040] Figure 17 This is a polarization curve of the fuel cell stack composed of the catalyst in Example 13. Detailed Implementation

[0041] To make the technical problems, technical solutions, and beneficial effects of this invention clearer and more understandable, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. The described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0042] In a first aspect, the present invention provides a catalyst slurry containing a molecular carbon electronic material, the catalyst slurry comprising: a molecular carbon electronic material, a platinum-based catalyst, a perfluorosulfonic acid ionomer (electrolyte), water, and an alcohol solvent.

[0043] In this invention, molecular carbon electronic materials are introduced into the catalyst slurry to construct a synergistic interface structure of "molecular electronic buffer and geometric shield" on the surface of the platinum-based catalyst. This simultaneously enhances the activity and durability of the oxygen reduction reaction at the fuel cell cathode and improves the mass transfer characteristics of the catalyst layer. Specifically, graphene and fullerene materials have strong electron acceptor properties, which can extract electrons from Pt sites and regulate the electronic structure of Pt, thereby optimizing the adsorption / desorption behavior of oxygen intermediates. At the same time, the permeable molecular shielding layer formed by graphene and fullerene can weaken the specific adsorption of sulfonic acid groups in perfluorosulfonic acid ionomers on Pt active sites, reduce ionomer poisoning, and facilitate the diffusion and transport of oxygen within the catalyst layer, thereby improving the overall performance of the fuel cell.

[0044] The C 50 The structural formula is shown in Equation I below:

[0045]

[0046] Formula I;

[0047] The C 60 The structural formula is shown in Figure II below:

[0048]

[0049] Formula II;

[0050] The C 70 The structural formula is shown in equation III below:

[0051]

[0052] Formula III;

[0053] The mass ratio of the molecular carbon electronic material to the perfluorosulfonic acid ionomer is 1:(1~800), for example, it can be 1:1, 1:2, 1:5, 1:10, 1:20, 1:30, 1:50, 1:80, 1:100, 1:150, 1:200, 1:300, 1:400, 1:500, 1:600, 1:700, 1:800, etc.

[0054] The platinum-based catalyst includes any one or a combination of at least two of Pt / C, PtCo / C, PtNi / C, PtFe / C, and PtCu / C, preferably PtCo / C.

[0055] The platinum-based catalyst contains 10% to 70% Pt by mass, for example, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, etc.

[0056] The perfluorosulfonic acid ionomer is a perfluororesin containing sulfonic acid groups. The perfluorosulfonic acid ionomer is selected from at least one of Nafion, Aquivion, Flemion, or Aciplex.

[0057] The alcohol is selected from any one or a combination of at least two of methanol, ethanol, n-propanol, isopropanol, n-butanol or tert-butanol, preferably isopropanol and / or n-propanol.

[0058] In a second aspect, the present invention provides a method for preparing a catalyst slurry containing graphene and fullerene molecular carbon electronic materials as described in the first aspect, the preparation method comprising the following steps:

[0059] (1) The molecular carbon electronic material and the perfluorosulfonic acid ionomer are mixed in an alcohol solvent and dispersed once to obtain a pre-dispersion;

[0060] (2) The platinum-based catalyst is added to the pre-dispersion liquid, and water and alcohol solvent are added and mixed for secondary dispersion to obtain the catalyst slurry.

[0061] It is important to note that currently widely used fuel cell catalyst slurry preparation methods involve directly mixing and ultrasonically dispersing the catalyst, perfluorosulfonic acid ionomer, deionized water, and organic solvents. This method easily leads to a strong coating of electrolyte on the catalyst surface, causing some active sites to be affected by ionomer adsorption. It may also result in a dense local structure of the catalyst layer, restricting oxygen diffusion and thus weakening performance under low Pt loading conditions. Therefore, this invention prioritizes the composite dispersion of molecular carbon electronic materials and electrolytes during slurry preparation, further ensuring sufficient contact with the platinum-based catalyst. The molecular carbon electronic materials form a permeable molecular layer on the catalyst surface, thereby reducing ionomer poisoning while balancing gas diffusion and mass transfer. Simultaneously, the electron acceptor effect of graphene and fullerene can modulate the electronic structure of Pt sites, optimizing the adsorption energy of oxygen intermediates, thereby improving the cathode ORR reaction kinetics and enhancing catalyst durability.

[0062] In step (1), the mass ratio of the molecular carbon electronic material to the alcohol solvent is 1:(50~2000), for example, it can be 1:50, 1:100, 1:200, 1:300, 1:500, 1:800, 1:1000, 1:1500, 1:2000, etc.

[0063] In step (1), the primary dispersion is ultrasonic dispersion or high-speed shear dispersion, the power of the primary dispersion is 20~500 W, and the time of the primary dispersion is 10~60 min.

[0064] In step (1), the mass ratio of the molecular carbon electronic material, perfluorosulfonic acid ionomer and alcohol is 1:(1~800):(50~2000).

[0065] In step (2), the mass ratio of the platinum-based catalyst, water, alcohol solvent and pre-dispersion liquid is 1:(10~200):(20~300):(0.5~20).

[0066] In step (2), the secondary dispersion is ultrasonic dispersion or high-speed shear dispersion, the power of the secondary dispersion is 20~500 W, and the time of the secondary dispersion is 10~60 min.

[0067] Thirdly, the present invention provides an application of the catalyst slurry as described in the first aspect in the preparation of fuel cells, preferably in the preparation of the cathode catalyst layer of a proton exchange membrane fuel cell.

[0068] Fourthly, the present invention provides a cathode catalyst layer comprising a catalyst layer formed from the catalyst slurry as described in the first aspect.

[0069] Fifthly, the present invention provides a membrane electrode assembly, the membrane electrode assembly comprising: a proton exchange membrane and a cathode catalyst layer and an anode catalyst layer located on both sides of the proton exchange membrane; wherein the cathode catalyst layer comprises the cathode catalyst layer as described in the fourth aspect.

[0070] In a sixth aspect, the present invention provides a fuel cell, the fuel cell including a membrane electrode assembly; wherein the membrane electrode assembly includes the membrane electrode assembly as described in the fifth aspect.

[0071] The present invention will be further illustrated by the following examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0072] Example 1

[0073] This embodiment provides a C-containing 70 A catalyst slurry for fullerene molecular carbon electronic materials, the catalyst slurry being prepared by the following steps:

[0074] S1, weigh 2.0 mg of C 70 Fullerene, 0.3 g Nafion (5 wt%) resin solution (specific model: D520) and 2.0 g isopropanol were mixed and ultrasonically dispersed at 100 W for 60 min to obtain a dispersion.

[0075] S2. Weigh 10 mg of Pt / C catalyst with a Pt content of 40%, add 0.2 g of deionized water, 1.0 g of isopropanol and 0.1 g of the dispersion prepared in S1, and ultrasonically disperse at 100 W for 60 min to obtain C-containing... 70 Catalyst slurry for fullerene molecular carbon electronic materials.

[0076] Example 2

[0077] This embodiment provides a C-containing 70 A catalyst slurry for fullerene molecular carbon electronic materials, the catalyst slurry being prepared by the following steps:

[0078] S1. Weigh 8.0 mg of C 70 Fullerene, 0.3 g Nafion (5 wt%) resin solution (specific model: D520) and 2.0 g isopropanol were mixed and ultrasonically dispersed at 100 W for 60 min to obtain a dispersion.

[0079] S2. Weigh 10 mg of Pt / C catalyst with a Pt content of 40%, add 0.2 g of deionized water, 1.0 g of isopropanol and 0.1 g of the dispersion prepared in S1, and ultrasonically disperse at 100 W for 60 min to obtain the C-containing catalyst.70 Catalyst slurry for fullerene molecular carbon electronic materials.

[0080] Example 3

[0081] This embodiment provides a C-containing 70 A catalyst slurry for fullerene molecular carbon electronic materials, the catalyst slurry being prepared by the following steps:

[0082] S1. Weigh 15.0 mg of C 70 Fullerene, 0.3 g Nafion (5 wt%) resin solution (specific model: D520) and 2.0 g isopropanol were mixed and ultrasonically dispersed at 100 W for 60 min to obtain a dispersion.

[0083] S2. Weigh 10 mg of Pt / C catalyst with a Pt content of 40%, add 0.2 g of deionized water, 1.0 g of isopropanol and 0.1 g of the dispersion prepared in S1, and ultrasonically disperse at 100 W for 60 min to obtain the C-containing catalyst. 70 Catalyst slurry for fullerene molecular carbon electronic materials.

[0084] Example 4

[0085] This embodiment provides a C-containing 60 A catalyst slurry for fullerene molecular carbon electronic materials, the catalyst slurry being prepared by the following steps:

[0086] S1, weigh 2.0 mg of C 60 Fullerene, 0.3 g Nafion (5 wt%) resin solution (specific model: D520) and 2.0 g isopropanol were mixed and ultrasonically dispersed at 100 W for 60 min to obtain a dispersion.

[0087] S2. Weigh 10 mg of Pt / C catalyst with a Pt content of 40%, add 0.2 g of deionized water, 1.0 g of isopropanol and 0.1 g of the dispersion prepared in S1, and ultrasonically disperse at 100 W for 60 min to obtain the C-containing catalyst. 60 Catalyst slurry for fullerene molecular carbon electronic materials.

[0088] Example 5

[0089] This embodiment provides a C-containing 84 A catalyst slurry for fullerene molecular carbon electronic materials, the catalyst slurry being prepared by the following steps:

[0090] S1, weigh 2.0 mg of C 84Fullerene, 0.3 g Nafion (5 wt%) resin solution (specific model: D520) and 2.0 g isopropanol were mixed and ultrasonically dispersed at 100 W for 60 min to obtain a dispersion.

[0091] S2. Weigh 10 mg of Pt / C catalyst with a Pt content of 40%, add 0.2 g of deionized water, 1.0 g of isopropanol and 0.1 g of the dispersion prepared in S1, and ultrasonically disperse at 100 W for 60 min to obtain the C-containing catalyst. 84 Catalyst slurry for fullerene molecular carbon electronic materials.

[0092] Example 6

[0093] This embodiment provides a C-containing 90 A catalyst slurry for fullerene molecular carbon electronic materials, the catalyst slurry being prepared by the following steps:

[0094] S1, weigh 2.0 mg of C 90 Fullerene, 0.3 g Nafion (5 wt%) resin solution (specific model: D520) and 2.0 g isopropanol were mixed and ultrasonically dispersed at 100 W for 60 min to obtain a dispersion.

[0095] S2. Weigh 10 mg of Pt / C catalyst with a Pt content of 40%, add 0.2 g of deionized water, 1.0 g of isopropanol and 0.1 g of the dispersion prepared in S1, and ultrasonically disperse at 100 W for 60 min to obtain the C-containing catalyst. 90 Catalyst slurry for fullerene molecular carbon electronic materials.

[0096] Example 7

[0097] This embodiment provides a C-containing 70 A catalyst slurry for fullerene molecular carbon electronic materials, the catalyst slurry being prepared by the following steps:

[0098] S1, weigh 2.0 mg of C 70 Fullerene, 0.3 g Nafion (5 wt%) resin solution (specific model: D520) and 2.0 g n-propanol were mixed and ultrasonically dispersed at 100 W for 60 min to obtain a dispersion.

[0099] S2. Weigh 10 mg of Pt / C catalyst with a Pt content of 40%, add 0.2 g of deionized water, 1.0 g of n-propanol and 0.1 g of the dispersion prepared in S1, and ultrasonically disperse at 100 W for 60 min to obtain the C-containing catalyst. 70 Catalyst slurry for fullerene molecular carbon electronic materials.

[0100] Example 8

[0101] This embodiment provides a catalyst slurry containing graphene carbon electronic material, which is prepared by the following steps:

[0102] S1. Weigh 2.0 mg of graphene, 0.3 g of Nafion (5 wt%) resin solution (specific model: D520) and 2.0 g of n-propanol, mix them, and ultrasonically disperse them at 100 W for 60 min to obtain a dispersion.

[0103] S2. Weigh 10 mg of Pt / C catalyst with a Pt content of 40%, add 0.2 g of deionized water, 1.0 g of n-propanol and 0.1 g of the dispersion prepared in S1, and ultrasonically disperse at 100 W for 60 min to obtain the catalyst slurry containing graphene molecular carbon electronic material.

[0104] Example 9

[0105] This embodiment provides a C-containing 76 A catalyst slurry for fullerene molecular carbon electronic materials, the catalyst slurry being prepared by the following steps:

[0106] S1, weigh 2.0 mg of C 76 Fullerene, 0.3 g Nafion (5 wt%) resin solution (specific model: D520) and 2.0 g isopropanol were mixed and ultrasonically dispersed at 100 W for 60 min to obtain a dispersion.

[0107] S2. Weigh 10 mg of Pt / C catalyst with a Pt content of 40%, add 0.2 g of deionized water, 1.0 g of isopropanol and 0.1 g of the dispersion prepared in S1, and ultrasonically disperse at 100 W for 60 min to obtain the C-containing catalyst. 76 Catalyst slurry for fullerene molecular carbon electronic materials.

[0108] Example 10

[0109] This embodiment provides a C-containing 78 A catalyst slurry for fullerene molecular carbon electronic materials, the catalyst slurry being prepared by the following steps:

[0110] S1, weigh 2.0 mg of C 78 Fullerene, 0.3 g Nafion (5 wt%) resin solution (specific model: D520) and 2.0 g isopropanol were mixed and ultrasonically dispersed at 100 W for 60 min to obtain a dispersion.

[0111] S2. Weigh 10 mg of Pt / C catalyst with a Pt content of 40%, add 0.2 g of deionized water, 1.0 g of isopropanol and 0.1 g of the dispersion prepared in S1, and ultrasonically disperse at 100 W for 60 min to obtain the C-containing catalyst. 78 Catalyst slurry for fullerene molecular carbon electronic materials.

[0112] Example 11

[0113] This embodiment provides a C-containing 70 A catalyst slurry for fullerene molecular carbon electronic materials, the catalyst slurry being prepared by the following steps:

[0114] S1. Weigh 4.0 mg of C 70 Fullerene, 0.12 g Nafion (5 wt%) resin solution (specific model: D520) and 4.0 g isopropanol were mixed and ultrasonically dispersed at 100 W for 60 min to obtain a dispersion.

[0115] S2. Weigh 20 mg of Pt / C catalyst with a Pt content of 40%, add 0.4 g of deionized water, 2.0 g of isopropanol and 0.2 g of the dispersion prepared in S1, and ultrasonically disperse at 100 W for 60 min to obtain the C-containing catalyst. 70 Catalyst slurry for fullerene molecular carbon electronic materials.

[0116] Example 12

[0117] This embodiment provides a C-containing 70 A catalyst slurry for fullerene molecular carbon electronic materials, the catalyst slurry being prepared by the following steps:

[0118] S1. Weigh 4.0 mg of C 70 Fullerene, 1.0 g Nafion (5 wt%) resin solution (specific model: D520) and 4.0 g isopropanol were mixed and ultrasonically dispersed at 100 W for 60 min to obtain a dispersion.

[0119] S2. Weigh 20 mg of Pt / C catalyst with a Pt content of 40%, add 0.4 g of deionized water, 2.0 g of isopropanol and 0.2 g of the dispersion prepared in S1, and ultrasonically disperse at 100 W for 60 min to obtain the C-containing catalyst. 70 Catalyst slurry for fullerene molecular carbon electronic materials.

[0120] Example 13

[0121] This embodiment provides a C-containing 70A catalyst slurry for fullerene molecular carbon electronic materials, the catalyst slurry being prepared by the following steps:

[0122] S1. Weigh 2.0 mg of C 70 Fullerene, 0.3 g Nafion (5 wt%) resin solution (specific model: D520) and 2.0 g isopropanol were mixed and ultrasonically dispersed at 100 W for 60 min to obtain a dispersion.

[0123] S2. Weigh 10 mg of a commercial PtCo / C catalyst with a Pt content of 48.4% and a Co content of 4.4%, add 0.2 g of deionized water, 1.0 g of isopropanol, and 0.1 g of the dispersion prepared in S1, and ultrasonically disperse at 100 W for 60 min to obtain the C-containing catalyst. 70 Catalyst slurry for fullerene molecular carbon electronic materials.

[0124] Comparative Example 1

[0125] This comparative example provides a method for preparing a commercial Pt catalyst slurry, the catalyst slurry being prepared by the following steps:

[0126] Weigh 10 mg of 40 wt% Pt / C catalyst, 0.06 g of Nafion (5 wt%) resin solution, 0.2 g of deionized water and 1.0 g of isopropanol, mix and sonicate for 60 min to obtain slurry.

[0127] Comparative Example 2

[0128] This comparative example provides a method for preparing a commercial PtCo catalyst slurry, which is prepared by the following steps:

[0129] 10 mg of a commercial PtCo / C catalyst with a Pt content of 48.4% and a Co content of 4.4% was weighed, and 0.06 g of Nafion (5 wt%) resin solution, 0.2 g of deionized water, and 1.0 g of isopropanol were added. The mixture was sonicated for 60 min to obtain a slurry.

[0130] Test case

[0131] Test samples: catalysts provided in Examples 1-13 and catalysts provided in Comparative Examples 1-2;

[0132] Test method:

[0133] I. Preparation of catalyst-coated membrane (CCM) and assembly of membrane electrode assembly (MEA):

[0134] Catalyst-coated membranes (CCMs) were prepared by ultrasonically spraying catalyst ink onto a proton exchange membrane. The proton exchange membrane was a GORE proton exchange membrane. During the spraying process, the anode platinum loading was controlled to be 0.10 mg. Pt cm -2 The cathode platinum loading is 0.05~0.10 mg. Pt cm -2 The CCM is sandwiched between two gas diffusion electrodes, which are carbon substrates with microporous layers; it is then assembled with a graphite bipolar plate with three serpentine flow channels and sealed with a silicone gasket to obtain a membrane electrode assembly (MEA).

[0135] The anode catalyst slurry was prepared as follows: 10 mg of 40 wt% Pt / C catalyst, 0.06 g of Nafion (5 wt%) resin solution, 0.2 g of deionized water and 1.0 g of isopropanol were weighed, mixed and sonicated for 60 min to obtain the anode catalyst slurry.

[0136] II. Electrochemical Rotating Disk Electrode (RDE) Test: A mirror-polished glassy carbon rotating disk electrode with a geometric area of ​​0.196 cm² was selected as the working electrode. 2 The catalyst ink was uniformly drop-coated onto the surface of a glassy carbon electrode using a micropipette method and allowed to dry naturally at room temperature to form a catalyst layer on the electrode surface; the final noble metal loading was controlled to be 4 μg. Pt cm 2 The working electrode was subjected to cyclic voltammetric activation in a 0.1 M perchloric acid (HClO4) electrolyte. The activation potential range was 0.05–1.25 V (relative to the reversible hydrogen electrode RHE), and the scan rate was 500 mV s. -1 .

[0137] III. Single-cell assembly and electrochemical performance testing: The Scriber 850e fuel cell testing system was used to test the single cells, specifically including the following steps:

[0138] (1) At 80℃, 100%RH, 150 kPa abs Under these conditions, with H2 / O2 as the reaction gas (anode / cathode flow rate of 200 / 200 sccm), the battery potential was sequentially maintained at 0.85 V, 0.60 V, 0.50 V and 0.40 V (each potential held for 5 min), and the above process was repeated until the current output stabilized.

[0139] (2) Polarization curve and power density test: at 80℃, 100%RH, and 150 kPa absPolarization curves were recorded under the condition that both electrodes were under the same back pressure. Under air conditions, H2 / air (no CO2) gas supply was used, and the anode / cathode flow rate was 500 / 1500 sccm; under pure oxygen conditions, H2 / O2 gas supply was used, and the anode / cathode flow rate was 500 / 500 sccm.

[0140] (3) Mass activity test: Under the same temperature and humidity conditions as above, the test was conducted at an H2 / O2 anode / cathode flow rate of 1000 / 1000 sccm, and the mass activity (MA) was calculated at 0.90 V (iR-free).

[0141] (4) Electrochemical impedance spectroscopy test: at 80℃, 100%RH, and 150 kPa abs (Both poles are under this back pressure) 5A cm -2 Polarization curves were recorded under current conditions. The gas flow rates at the anode and cathode were 500 sccm / 500 sccm, the gas inlet pressures were 50 kPa / 50 kPa, and the humidity at both the anode and cathode was 100% RH.

[0142] (5) In-situ infrared testing: In-situ surface-enhanced infrared absorption (SEIRAS) testing was performed using a Fourier transform infrared spectrometer. Spectra were acquired in ATR mode with a resolution of 8 cm⁻¹. -1 Before testing, a gold thin film was deposited on the surface of a silicon prism and electrochemically cleaned in 0.5 M H₂SO₄. Catalyst ink, obtained by ultrasonic dispersion, was dropped onto the gold thin film surface and dried to form a catalyst layer, which was then used as the working electrode in a three-electrode flow cell. The counter electrode was a graphite rod, and the reference electrode was a KCl-saturated calomel electrode (SCE). The electrolyte was 0.1 M HClO₄ (99.9%) saturated with O₂, with O₂ continuously introduced at a flow rate of 20 sccm. Electrochemical scanning was performed using linear sweep voltammetry (LSV) with a potential range of 1.1–0.3 V (vs. RHE) and a scan rate of 5 mV / s. -1 .

[0143] (6) Single-crystal electrochemical testing (Pt(111)): The Pt(111) single-crystal electrode was annealed with a butane flame and then cooled in an Ar / H2 mixed atmosphere; after cooling to room temperature, a drop of ultrapure water was placed on the electrode surface for protection. A Nafion coating solution was prepared by diluting a commercial Nafion D520 (5wt%) dispersion 1000 times with ultrapure water, and C was added to it. 70 0.01% Nafion / C was obtained. 70 Mixed solution. 5 μL of the mixed solution was dropped onto the Pt(111) surface covered with ultrapure water, and then dried in an argon atmosphere; finally, cyclic voltammetry was performed in 0.1 M HClO4 electrolyte.

[0144] (7) Fuel cell stack testing: The MEA was prepared by ultrasonically spraying catalyst ink onto the GORE proton exchange membrane. The anode was a commercial 40% Pt / C with a Pt loading of 0.05 mg. Pt cm -2 The cathode Pt loading was 0.1~0.2 mg. Pt cm -2 The polarity load was verified using ICP-OES. The MEA was assembled into a 20-cell stack (40cm per cell). 2 The reactor was tested using a graphite bipolar plate with a 13-channel serpentine flow path and on an ALTF-2500 fuel cell stack testing system. The stack activation conditions were: H2 / air, 80°C, 100%RH, 200 kPa. abs Maintain the single-cell voltage at 0.5 V until the current stabilizes; then maintain it at 80℃ and 200 kPa. abs Polarization curves were collected under 100% RH conditions, with the air condition being H2 / air (no CO2) and the stoichiometric ratio being 1.5 / 2.5 (anode / cathode), and the oxygen condition being H2 / O2 with the stoichiometric ratio being 1.5 / 2.

[0145] Furthermore, the experimental results of this invention are shown in the following figure:

[0146] Figure 1 The C-containing sample provided in Example 1 70 Transmission electron microscopy (TEM) image of a fullerene-modified Pt / C catalyst. The image shows that C... 70 Fullerenes are modified on Pt surfaces.

[0147] Figure 2 This is a transmission electron microscope image of the PtCo catalyst provided in Example 13. Figure 2 It can be seen that the PtCo catalyst particles are uniformly distributed on the carbon support.

[0148] Figure 3 The graph shows a comparison of polarization and power density curves for membrane electrode assemblies (MEAs) containing catalyst layers formed from catalyst slurries of Example 1 and Comparative Example 1. As can be seen from the graph, Example 1 exhibits a significantly improved power density.

[0149] Figure 4 and Figure 5 The figure shows a comparison of the polarization curves and measured mass activities of fuel cells containing the catalyst membrane electrode assembly of Example 1 and Comparative Example 1. As shown in the figure, the mass activity of Example 1 is higher than that of Comparative Example 1, indicating that the C... 70 Fullerene modification increases the number of active sites for Pt.

[0150] Figure 6 This is a comparison graph showing the stability of catalysts from Example 1 and Comparative Example 1. As can be seen from the graph, the stability of Example 1 is significantly improved.

[0151] Figure 7 and Figure 8 The figures show the RDE polarization curves and mass activity comparisons of the catalysts from Examples 1, 4, 5, and Comparative Example 1. As can be seen from the figures, the mass activity of Example 1 is significantly improved.

[0152] Figure 9 The graphs show a comparison of polarization and power density curves for fuel cells containing catalysts from Examples 1, 4, 3, and Comparative Example 1. As can be seen from the graphs, Example 1 exhibits a significantly improved power density.

[0153] Figure 10 The graphs show a comparison of polarization curves and power density curves for fuel cells containing catalysts from Examples 6, 9, and 10. As can be seen from the graphs, the power density of the fuel cells in the embodiments of the present invention is significantly improved compared to Comparative Example 1.

[0154] Figure 11 The graph shows a comparison of the polarization curves and power density curves of the fuel cell containing the catalyst of Example 13. As can be seen from the graph, the power density of the fuel cell of Example 13 is significantly improved compared to Comparative Example 2.

[0155] Figure 12 and Figure 13 For membrane electrode fuel cells containing catalyst layers formed from catalyst slurries of Example 1 and Comparative Example 1, at 5 A cm⁻¹ -2 The electrochemical impedance spectroscopy (EIS) comparison is shown below. It can be seen that at this current density, the polarization of the fuel cell is mainly controlled by oxygen transport polarization at the catalyst / electrolyte interface, and the larger the impedance semicircle diameter, the more severe the mass transfer polarization. As can be seen from the figure, compared with Comparative Example 1, the impedance semicircle diameter of Example 1 is significantly reduced, indicating that C... 70 Fullerenes effectively improve the mass transport rate inside fuel cells.

[0156] Figure 14 The image shown is the in-situ infrared spectrum of Comparative Example 1. Figure 15 This is the in-situ infrared spectrum of Example 1. From the obtained infrared spectrum, it can be seen that C in Example 1... 70 The introduction of fullerenes can rapidly generate a large amount of water as a reaction intermediate, which proves that C 70 It can accelerate ORR dynamics.

[0157] Figure 16 This is a diagram of the fuel cell stack comprising Example 13. Figure 17The graph shows the polarization curves of the fuel cell stack composed of Example 13. As can be seen from the graph, the fuel cell stack constructed with the catalyst slurry of this invention exhibits good output voltage and power output capabilities over a wide current density range, further verifying the applicability and stability of the molecular carbon electronic material modification strategy described in this invention at the fuel cell stack level.

[0158] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A catalyst slurry for fuel cells, characterized in that, include: The composition comprises: molecular carbon electronic materials, platinum-based catalysts, perfluorosulfonic acid ionomers, water, and alcohol solvents; wherein the molecular carbon electronic materials are selected from at least one of fullerenes and graphene; the fullerenes include C 50 C 60 C 70 C 76 C 78 C 84 C 90 At least one of them.

2. The catalyst slurry for fuel cells as described in claim 1, characterized in that: The platinum-based catalyst includes at least one of Pt / C, PtCo / C, PtNi / C, PtFe / C, and PtCu / C; the platinum content in the platinum-based catalyst is 10wt% to 70wt% by mass.

3. The catalyst slurry for fuel cells as described in claim 1, characterized in that: The perfluorosulfonic acid ionomer is selected from at least one of Nafion, Aquivion, Flemion, or Aciplex; the alcohol solvent is selected from at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol, or tert-butanol.

4. A method for preparing the catalyst slurry according to any one of claims 1 to 3, characterized in that, Includes the following steps: 1) Molecular carbon electronic materials and perfluorosulfonic acid ionomers are mixed and dispersed in an alcohol solvent to obtain a pre-dispersion; 2) The platinum-based catalyst is added to the pre-dispersion liquid, and then water and alcohol solvent are added and mixed to disperse the catalyst slurry.

5. The preparation method according to claim 4, characterized in that: The dispersion is performed by ultrasonic dispersion and / or high-speed shear dispersion; the ultrasonic power is 20-500 W, and the dispersion time is 10-120 min.

6. The preparation method according to claim 4, characterized in that: In step 1), the mass ratio of the molecular carbon electronic material, perfluorosulfonic acid ionomer, and alcohol solvent is 1:(1-800):(50-2000); in step 2), the mass ratio of platinum-based catalyst, water, alcohol solvent, and pre-dispersion liquid is 1:(10-200):(20-300):(0.5-20); and the mass ratio of the molecular carbon electronic material to the platinum-based catalyst is 1:(0.5-100).

7. The application of the catalyst slurry according to any one of claims 1 to 3 in the preparation of the cathode catalyst layer of a proton exchange membrane fuel cell.

8. A cathode catalyst layer, characterized in that, The catalyst slurry as described in any one of claims 1 to 3 is obtained by spraying or scraping to form a film.

9. A membrane electrode assembly, characterized in that, It includes a proton exchange membrane and a cathode catalyst layer and an anode catalyst layer located on both sides thereon; wherein the cathode catalyst layer is the cathode catalyst layer as described in claim 8.

10. A single cell or stack of fuel cells, characterized in that, It includes the membrane electrode assembly as described in claim 9.

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