Anode catalysts with anti-reverse polarity properties, preparation methods, slurries and fuel cells

Abstract

This invention belongs to the field of new energy fuel cell technology, and specifically relates to an anode catalyst with anti-reverse polarity, its preparation method, slurry, and fuel cell. The catalyst includes a support and a Pt-Ru alloy and IrO2 supported on the support, wherein the support is a carbon material support; the particle size of the anti-reverse polarity anode catalyst is 3-5 nm. Addressing the technical deficiencies of existing anti-reverse polarity anode catalysts, this invention proposes an improved anti-reverse polarity anode catalyst. This catalyst uses a carbon material support with superior conductivity and mass transfer capacity compared to metal oxide supports such as TiO2, ZrO2, WO3-Mn, and Nb-TiO2. IrO2, which has high anti-reverse polarity performance, is co-supported with the metal active component Pt-Ru alloy on the carbon material support. The resulting anti-reverse polarity anode catalyst, when applied to a fuel cell, exhibits a reverse polarity time of 171 min and an electrode performance of 1.40 A / cm² after reverse polarity. 2 In addition, this anode catalyst also exhibits excellent resistance to CO poisoning.

Description

Technical Field

[0001] This invention belongs to the field of new energy fuel cell technology, and specifically relates to an anode catalyst with anti-reverse polarity properties, its preparation method, slurry, and fuel cell. Background Technology

[0002] Proton exchange membrane fuel cells (PEMFCs) are clean and efficient energy conversion devices that convert the chemical energy of hydrogen and oxygen into electrical energy through a catalytic reaction without causing environmental pollution. Therefore, PEMFCs have broad application prospects in building power supply, backup power, public transportation, fixed base stations, and aviation.

[0003] The membrane electrode assembly (MEA) is the smallest unit for power generation in a fuel cell. Because a single MEA has a low output voltage, dozens or even hundreds of these components are typically connected in series using bipolar plates to form a battery pack. In practical applications, PEMFCs encounter harsh conditions such as impurities clogging gas transport channels, flooding, start-up and shutdown, and rapid load changes. These can cause fuel shortages in the anode catalyst layer. To maintain charge balance, carbon corrosion and oxygen evolution reaction (OER) occur in the anode catalyst layer. These reactions are competitive; increasing the OER rate helps suppress carbon corrosion, thus preventing performance loss of the MEA under harsh conditions. However, the OER reaction typically requires a potential greater than 2V, higher than the potential for carbon corrosion. To reduce the overpotential of OER, it is necessary to introduce OER active components to maintain proton and charge balance at a relatively low potential, thereby preventing carbon corrosion.

[0004] Currently, there are two main approaches to improve the anti-reverse polarity performance of fuel cell membrane electrodes: the first approach is to prepare the anode catalyst layer using anti-reverse polarity catalysts. Anti-reverse polarity catalysts mainly fall into two categories: one uses non-carbon supports to support Pt, such as metal oxides as Pt supports. This type of fuel cell effectively avoids carbon support corrosion caused by reverse polarity due to the use of non-carbon materials as supports, thus protecting the catalyst layer structure and improving battery durability. However, there are drawbacks: metal oxides used as catalyst supports, such as TiO2, ZrO2, WO3, Mn, and Nb-TiO2, have much lower conductivity and mass transfer capacity than carbon supports. Therefore, using metal oxides as catalyst supports will reduce fuel cell performance.

[0005] Another approach is to add an OER catalyst to the anode catalyst layer to enhance the reverse polarity resistance of the fuel cell. For example, existing journal literature discloses the preparation of an anode catalyst layer slurry by dispersing IrO2, Pt / C catalyst, and Nafion in a mixed solvent of H2O / isopropanol, which is then sprayed onto one side of the proton exchange membrane to form the anode catalyst layer. Due to the differences in physical properties between OER catalysts and Pt / C catalysts, OER catalysts such as IrO2, RuO2, and IrRu... x O y Due to its poor conductivity and small specific surface area, it cannot be fully mixed with Pt / C catalyst. This causes uneven distribution of OER catalyst in the anode catalyst layer, resulting in a sharp decline in fuel cell performance after one reverse polarity test. Summary of the Invention

[0006] The purpose of this invention is to overcome the poor performance, poor stability, and rapid performance degradation after a single reverse electrode reaction in fuel cells prepared using anti-reverse electrode anode catalysts in the prior art, as well as the H2O caused by the poor conductivity of the OER catalyst layer. + e - To address defects such as poor battery performance caused by difficulties in the transport of related substances, this paper provides an anode catalyst with anti-reverse polarity properties, a preparation method, a slurry, and a fuel cell.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] A proton exchange membrane fuel cell anti-reverse anode catalyst includes a support and a Pt-Ru alloy and IrO2 supported on the support, wherein the support is a carbon material support; in the anti-reverse anode catalyst, the particle size of both the Pt-Ru alloy and IrO2 is maintained between 3-5 nm.

[0009] This invention addresses the technical deficiencies of existing anti-reverse-polarity anode catalysts by proposing an improved anti-reverse-polarity anode catalyst. This catalyst uses a carbon material as a support, which exhibits superior conductivity and mass transfer capabilities compared to metal oxide supports such as TiO2, ZrO2, WO3-Mn, and Nb-TiO2. IrO2, which has high anti-reverse-polarity properties, is co-supported with a Pt-Ru alloy, a metallic active component, on this carbon material support. Performance testing of the resulting anti-reverse-polarity anode catalyst in a fuel cell showed that it maintained a reverse-polarity time of 171 min, and the electrode performance after reverse-polarity remained at 1.40 A / cm². 2 In addition, this anode catalyst also exhibits excellent resistance to CO poisoning.

[0010] During the research and development process, the inventors discovered that the particle size of the catalyst has a certain impact on its performance. When the particle size of the noble metal is less than 2 nm, the catalyst's durability is poor; when the particle size of the noble metal is greater than 5 nm, the catalyst utilization rate is low, leading to a decline in performance. In the anti-reverse polarity anode catalyst of this invention, the particle size of the noble metals (including iridium oxide and platinum-ruthenium alloy) is maintained between 3-5 nm. This is crucial for maintaining the overall comprehensive performance of the catalyst. As a preferred embodiment of this invention, the particle size of the anode catalyst is 3-4 nm.

[0011] Furthermore, as the Ir content increases, the anti-reverse polarity performance of the catalyst is continuously enhanced. However, IrO2 has poor conductivity. When the mass ratio of Ir:PtRu exceeds 1:1, the performance of the battery will drop sharply. When the Ir content is too low, it will reduce the anti-reverse polarity time of the membrane electrode. In order to find a balance between high HOR activity, CO poisoning resistance and anti-reverse polarity performance, as a preferred technical solution of the present invention, the mass ratio of the Pt-Ru alloy to Ir is 4:1-4:3.

[0012] Studies have found that Pt adsorbs CO molecules, while Ru can adsorb OH-. - It is generally believed that the pathway of Pt-COads + Ru-OHads → PtRu + CO2 can prevent CO from occupying the active sites of Pt, thus preventing catalyst poisoning and a decline in battery performance. Therefore, it is preferable to incorporate an appropriate amount of ruthenium metal into the Pt / C catalyst system. Extensive experimental testing has shown that when the mass ratio of Pt:Ru is 4:1, the fuel cell exhibits low resistance to CO poisoning without significantly impacting battery performance. When the mass ratio of Pt:Ru is 2:1, the fuel cell exhibits high resistance to CO poisoning, but battery performance is somewhat reduced. As a preferred embodiment of this invention, the mass ratio of Pt to Ru in the Pt-Ru alloy is 4:1-2:1.

[0013] A method for preparing the above-mentioned anti-reverse anode catalyst for proton exchange membrane fuel cells includes the following steps:

[0014] S1: Preparation of Ir / C: Carbon support, iridium precursor, and reducing alcohol are added to an alkaline solution and uniformly dispersed to obtain a mixed slurry. After heating and reflux reaction, the pH of the mixed slurry is adjusted to acidic, and Ir / C is obtained by washing and filtration. The purpose of this step is to prepare Ir / C with a low particle size in advance. This step requires the Ir particle size to be about 1 nm. Temperature and time have the most critical effects on this. When the temperature is higher, the Ir particle size is larger and the yield is higher; when the temperature is lower, the particle size is smaller and the yield is lower. Preferably, the reflux temperature range is 140-180℃; more preferably, the optimal temperature should be 150-160℃.

[0015] Furthermore, the reflux time also affects the particle size. The Ir particle size increases with the extension of reaction time, and the amount of Ir loaded on the carbon also increases with the extension of time. Taking all factors into consideration, the reflux time should be 1-3 hours, with the optimal value being 1.5-2 hours.

[0016] S2: Preparation of IrO2 / C: The Ir / C is heat-treated by passing it through a N2 / O2 mixture to obtain IrO2 / C. In this step, it is required that all Ir is converted into IrO2 with a particle size of 3-5 nm. In this process, it is necessary to control the calcination temperature. If the temperature is too low, Ir will not be able to be converted into IrO2. If the temperature is too high, the IrO2 particle size will increase sharply. Preferably, the heat treatment temperature is 300-550℃; more preferably, the optimal temperature range is 350-450℃.

[0017] Secondly, the heat treatment time needs to be controlled. A longer time results in larger precious metal particle sizes, while a shorter time will not allow for the complete transformation of Ir to IrO2. Preferably, the heat treatment time is 1-3 hours, and more preferably, it is controlled within 1.5-2 hours.

[0018] In an N2 / O2 mixture, excessively high O2 content can easily lead to the oxidation of carbon materials, making it difficult to control the mass fraction of IrO2. Conversely, excessively low oxygen content prevents complete conversion of Ir into IrO2. As a preferred embodiment of this invention, the optimal oxygen content range is 30%-40%.

[0019] S3: Preparation of PtRu-IrO2 / C: Pt and Ru metal precursors were mixed with IrO2 / C, and a reducing agent was added to react and obtain PtRu-IrO2 / C.

[0020] Specifically, the preparation of PtRu-IrO2 / C includes, but is not limited to, the following methods:

[0021] Scheme 1: Dissolve the metal precursors of Pt and Ru and NaOH in a reducing alcohol solvent and heat to reduce to obtain a PtRu colloidal solution. Cool to 50-80℃ and mix with ethylene glycol slurry of IrO2 / C. Adjust the pH of the solution to acidic and stir for 2-4 hours to obtain PtRu-IrO2 / C.

[0022] Option 2: Pt and Ru metal precursors, IrO2 / C, are separately sheared in deionized water to form slurries. Excess formic acid is added, and the pH of the system is adjusted to be greater than 8 with NaHCO3 solution. The system is heated to reflux, and N2 is continuously introduced into the system. After cooling to room temperature, PtRu-IrO2 / C is obtained by filtration.

[0023] Option 3: Prepare a slurry by high-speed shearing of Pt and Ru metal precursors with IrO2 / C in deionized water, heat the slurry and adjust the pH of the system to be greater than 8 by NaHCO3 solution, continuously introduce high-purity hydrogen into the system for 3-5 hours, and filter the system to obtain PtRu-IrO2 / C after the system cools to room temperature.

[0024] In the anti-reverse anode catalyst obtained by the above method, the particle sizes of platinum, ruthenium, and iridium oxide are all maintained at 3-4 nm, within which both catalytic activity and durability are considered. Furthermore, the noble metals are uniformly distributed, achieving a uniform distribution of IrO2 and Pt-Ru alloy throughout the catalyst layer. Through the preparation method of this invention, the carbon support surface is oxidized to a certain extent after the heat treatment in step S2, introducing a certain amount of oxygen-containing groups, which provides corresponding active sites for the loading of the platinum-ruthenium alloy in step S3. This also allows iridium oxide to be uniformly dispersed in the catalyst slurry.

[0025] By introducing ruthenium metal and iridium oxide into the Pt / C catalyst system and controlling the particle size and distribution of the noble metals, the thickness of the anode catalyst layer was reduced to some extent. Using IrO2 / C as the support for the Pt-Ru alloy reduced the amount of carbon material used and increased the catalyst's bulk density. With the same anode noble metal loading, this catalyst results in a thinner catalyst layer, which is more conducive to mass transfer and thus enhances battery performance.

[0026] The anodic anti-reverse catalyst formed by the oxidation of carbon-supported iridium to form carbon-supported iridium oxide has relatively uniform nanoparticle size and distribution.

[0027] As a preferred embodiment of the present invention, the carbon material carrier is a graphitized carbon material.

[0028] As a preferred embodiment of the present invention, in S1, the reducing alcohol includes any one of methanol, ethylene glycol, ethanol, propanol, and glycerol;

[0029] Preferably, the iridium metal precursor is any one of chloroiridium acid and iridium trichloride;

[0030] Preferably, the mass fraction of the iridium metal in the carbon-supported iridium is 20-40%.

[0031] As a preferred technical solution of the present invention, in S3, the precursor of Pt is selected from any one of chloroplatinic acid, platinum nitrate, and platinum acetylacetonate.

[0032] The precursor of ruthenium can be any one of ruthenium trichloride, ruthenium nitrate, or ruthenium acetylacetonate.

[0033] A fuel cell anti-reverse anode catalyst slurry, the anode catalyst slurry comprising the aforementioned anti-reverse anode catalyst PtRu-IrO2 / C, and further comprising perfluorosulfonic acid resin, propanol, and deionized water, wherein the PtRu-IrO2 / C, perfluorosulfonic acid resin, propanol, and deionized water are mixed in proportion and then uniformly dispersed to obtain a mixed slurry, which is the anode catalyst slurry.

[0034] A fuel cell, wherein the anode catalyst layer in the fuel cell comprises at least one anode catalyst layer prepared from the above-mentioned anti-reverse anode catalyst slurry.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] This invention addresses the technical deficiencies of existing anti-reverse-polarity anode catalysts by proposing an improved anti-reverse-polarity anode catalyst. This catalyst uses a carbon material as a support, which exhibits superior conductivity and mass transfer capabilities compared to metal oxide supports such as TiO2, ZrO2, WO3-Mn, and Nb-TiO2. IrO2, which has high anti-reverse-polarity properties, is co-supported with a Pt-Ru alloy, a metallic active component, on this carbon material support. Performance testing of the resulting anti-reverse-polarity anode catalyst in a fuel cell showed that it maintained a reverse-polarity time of 171 min, and the electrode performance after reverse-polarity remained at 1.40 A / cm². 2 In addition, the anode catalyst also exhibits a certain degree of resistance to CO poisoning.

[0037] By employing a method of oxidizing iridium on carbon to obtain iridium oxide on carbon, the final anti-reverse anode catalyst maintains a particle size of 3-4 nm for both the Pt-Ru alloy and IrO2. Within this range, both catalytic activity and durability are balanced. Moreover, the noble metals are evenly distributed, achieving uniform distribution of IrO2 and Pt-Ru alloy throughout the catalyst layer.

[0038] The above-described method for preparing anti-reverse anode catalysts allows for a certain degree of oxidation of the carbon support surface, introducing a certain amount of oxygen-containing groups, which provides corresponding sites for the loading of platinum-ruthenium alloy. It also ensures that iridium oxide is uniformly dispersed in the catalyst slurry.

[0039] By using IrO2 / C as the support for the PtRu alloy and controlling the particle size and distribution of the noble metal, the amount of carbon material used can be reduced to a certain extent, the bulk density of the catalyst can be increased, and the thickness of the anode catalyst layer can be reduced, which is more conducive to mass transport and thus improves the performance of the membrane electrode.

[0040] The fuel cell prepared using the anti-reverse anode catalyst described in this invention can achieve the functions of catalytic HOR, anti-reverse anode, and CO tolerance. Attached image description:

[0041] Figure 1 TEM images of the catalysts prepared in Examples 1-3 at a 50 nm scale; (1a represents catalyst PtRu-IrO2 / C-1, 2a represents catalyst PtRu-IrO2 / C-2, 3a represents catalyst PtRu-IrO2 / C-3);

[0042] Figure 2 TEM images of the catalysts prepared in Comparative Examples 1-2 at a 50 nm scale.

[0043] Figure 3 The OER curves of the working electrodes prepared in Example 4, Comparative Example 3, and Comparative Example 4 are shown.

[0044] Figure 4 The following are single-shutdown reverse polarity curves for each catalytic membrane electrode in Example 5 and Comparative Example 5;

[0045] Figure 5 The diagram shows the wall adhesion test of the slurry prepared in Example 4 and Comparative Example 4. Detailed Implementation

[0046] The present invention will be further described in detail below with reference to experimental examples and specific embodiments. However, this should not be construed as limiting the scope of the above-mentioned subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0047] Example 1

[0048] Preparation of anti-reverse anode catalyst: PtRu-IrO2 / C-1

[0049] S1. Mix 0.5g of graphitized carbon carrier material, chloroiridium acid (containing 100mg Ir), ethylene glycol, and NaOH to obtain a mixed slurry with a pH of approximately 13, and shear disperse for 30min. Transfer the shear dispersed mixed slurry to a three-necked flask; heat and reflux at 140℃ for 2h, then stop heating; after cooling, add concentrated hydrochloric acid to adjust the pH of the mixed slurry to <2, filter, and collect the filter residue; wash and filter the filter residue, and when the conductivity of the filtrate is less than 10μS / cm, place the filter residue in a vacuum drying oven to dry, and obtain Ir / C.

[0050] S2. Place the dried Ir / C in a tube furnace and purge with N2 / O2 (O2 content is 30%) at a flow rate of 50 mL / min. First, pre-purge for 30 min to remove other gases from the tube, then heat to 300℃ (heating rate 5℃ / min) and hold for 2 h to obtain IrO2 / C.

[0051] S3. Ruthenium trichloride (containing 50 mg Ru), chloroplatinic acid (approximately 200 mg Pt), ethylene glycol, and NaOH were mixed to obtain a mixed solution with a pH of 13, and the solution was transferred to a three-necked flask. The mixture was heated at 130°C and refluxed for 2 hours, and then the heating was stopped. When the system cooled to 60°C, a slurry of IrO2 / C and ethylene glycol was added, and the mixture was sheared at high speed for 60 minutes to obtain a mixed slurry. The pH of the system was adjusted to <2 with hydrochloric acid, and the mixture was stirred for another 2 hours to load PtRu onto IrO2 / C. The residue was then filtered. The residue was washed, and when the conductivity of the filtrate was less than 10 μS / cm, the residue was dried in a vacuum drying oven to obtain PtRu-IrO2 / C-1. The mass ratio of Pt-Ru alloy to Ir in the prepared catalyst was 2:1.

[0052] Example 2

[0053] Preparation of anti-reverse anode catalyst: PtRu-IrO2 / C-2

[0054] In the preparation of PtRu-IrO2 / C-2, the preparation method of IrO2 / C is the same as in Example 1;

[0055] S3. IrO2 / C, ruthenium trichloride (containing 50 mg Ru), chloroplatinic acid (approximately 200 mg Pt), and deionized water were prepared into a slurry by high-speed shearing and transferred to a three-necked flask. Excess formic acid (approximately 200 mL) was added to the system, and the pH of the system was adjusted to 10 with NaHCO3 solution. The system was heated at 130°C and refluxed for 2 hours, and then heating was stopped. N2 was continuously introduced into the system until it cooled to room temperature (to prevent the PtRu from being oxidized during the cooling process). The filter residue was collected and washed. When the conductivity of the filtrate was less than 10 μS / cm, the filter residue was dried in a vacuum drying oven to obtain PtRu-IrO2 / C-2. The mass ratio of PtRu alloy to Ir in the prepared catalyst was 2:1.

[0056] Example 3

[0057] Preparation of anti-reverse anode catalyst: PtRu-IrO2 / C-3

[0058] In the preparation of PtRu-IrO2 / C-3, the preparation method of IrO2 / C is the same as in Example 1;

[0059] S3. IrO2 / C, ruthenium trichloride (containing 50 mg Ru), chloroplatinic acid (approximately 200 mg Pt), and deionized water were prepared into a slurry by high-speed shearing and transferred to a three-necked flask. The slurry was heated to 60°C, and the pH of the system was adjusted to 10 with NaHCO3 solution. High-purity hydrogen gas was continuously introduced into the system for 3-5 hours. After the system cooled to room temperature, the residue was filtered and washed. When the conductivity of the filtrate was less than 10 μS / cm, the residue was dried in a vacuum drying oven to obtain PtRu-IrO2 / C-3. The mass ratio of PtRu alloy to Ir in the prepared catalyst was 2:1.

[0060] The catalysts PtRu-IrO2 / C obtained in Examples 1-3 above were characterized by TEM, such as... Figure 1 Images a, 1b, and 1c show the catalysts from Examples 1-3 on a 50 nm scale, respectively. The images show that the noble metal particles on the catalysts are basically uniformly distributed, with a particle size of approximately 5 nm.

[0061] Example 4

[0062] Using the catalyst PtRu-IrO2 / C-1 obtained in Example 1 as a raw material, it was dispersed together with perfluorosulfonic acid resin, propanol, and H2O in a homogenizer to form a mixed slurry. The slurry was then coated onto a glassy carbon electrode to prepare working electrode-1, wherein the Ir loading on the electrode was 30 μg / cm³. 2 .

[0063] Example 5

[0064] The catalysts from Examples 1-3 were prepared into mixed slurries according to the method described in Example 4, denoted as Slurry 1-A, Slurry 2-A, and Slurry 3-A. Anode catalyst layers were then prepared by spraying using these mixed slurries as raw materials, wherein the PtRu loading was 0.1 mg / cm³. 2 The Ir loading was 50 μg / cm³. 2 The cathode catalyst layer was prepared using 60 wt% Pt / C, with a Pt loading of 0.3 mg / cm³. 2 Finally, catalytic membrane electrode 1-A, catalytic membrane electrode 2-A and catalytic membrane electrode 3-A were obtained.

[0065] Comparative Example 1

[0066] A method for preparing an anti-reverse polarity anode catalyst (denoted as PtRu-IrO2 / C-4) is the same as that in Example 1, except that the preparation method of IrO2 / C is different.

[0067] The preparation of IrO2 / C specifically includes the following steps:

[0068] 0.5 g of graphitized carbon carrier material, chloroiridium acid (containing 100 mg Ir), and deionized water were dispersed by shearing to obtain a mixed slurry, which was then transferred to a three-necked flask. The system was heated to 100 °C, and NaOH was slowly added until the system changed from reddish-brown to blue (i.e., from chloroiridium acid to iridium hydroxide). After the system cooled to room temperature, it was filtered and washed. When the conductivity of the filtrate was less than 10 μS / cm, the filter residue was placed in a forced-air drying oven for drying to obtain Ir(OH)4 / C. Ir(OH)4 / C was then heat-treated at 350 °C in air for 2 h to obtain IrO2 / C.

[0069] Comparative Example 2

[0070] A method for preparing a reverse-polarity anode catalyst (denoted as PtRu / C-IrO2) specifically includes the following steps:

[0071] S1. Mix chloroiridium acid (containing 100 mg Ir), ethylene glycol, and NaOH to obtain a mixed solution with a pH of approximately 13, and transfer it to a three-necked flask; heat to 140°C and reflux for 2 hours, then stop heating and allow it to cool. Add concentrated hydrochloric acid to adjust the pH of the mixed slurry to <2, filter, and collect the filter residue; wash and filter the filter residue. When the conductivity of the filtrate is less than 10 μS / cm, place the filter residue in a vacuum drying oven to dry, and obtain elemental Ir.

[0072] S2. Place the dried Ir element in a tube furnace and purge with N2 / O2 (O2 content is 20%) at a flow rate of 50 mL / min. First, pre-purge for 30 min to remove other gases from the tube, then raise the temperature to 300℃ (heating rate 5℃ / min) and hold for 2 h to obtain IrO2.

[0073] S3. Mix 0.5g of graphitized carbon support material, ruthenium trichloride (containing 50mg Ru), chloroplatinic acid (approximately 200mg Pt), ethylene glycol, and NaOH to obtain a mixed slurry with a pH of 13, and transfer it to a three-necked flask; heat at 130℃ and reflux for 2 hours, then stop heating; when the system cools to 60℃, adjust the pH of the system to <2 with hydrochloric acid, and continue stirring for 2 hours to load PtRu onto the carbon support material, then filter and collect the filter residue. Wash and filter the filter residue; when the conductivity of the filtrate is less than 10μS / cm, place the filter residue in a vacuum drying oven to dry, and obtain PtRu / C.

[0074] S4: PtRu / C-IrO2 is obtained by grinding and mixing IrO2 and PtRu / C.

[0075] The catalysts PtRu-IrO2 / C-4 obtained in Comparative Example 1 and PtRu / C-IrO2 obtained in Comparative Example 2 were characterized by TEM, as follows: Figure 2 As shown, the images of the catalysts in Comparative Example 1 and Comparative Example 2 are displayed on a 50 nm scale. Figure 2 a represents the catalyst PtRu-IrO2 / C-4 obtained in Comparative Example 1. As can be seen from the image, the noble metal particles exhibit large agglomerations with a particle size of approximately 20 nm. This may be due to the relatively large particle size of the IrO2 / C prepared by the method in Comparative Example 1, which, when supported by PtRu, further exacerbates this agglomeration. Figure 2 b is the catalyst PtRu / C-IrO2 obtained in Comparative Example 2. As can be seen from the image, the distribution of noble metal particles is not very uniform, with an average particle size of about 4 nm, and the distribution of noble metal is relatively dense in some areas. This indicates that the physical mixing method is not conducive to the uniform distribution of noble metal on the support.

[0076] Comparative Example 3

[0077] The catalyst obtained in Comparative Example 1 was used as a raw material and dispersed together with perfluorosulfonic acid resin, propanol, and H2O in a homogenizer to form a mixed slurry. The slurry was then coated onto a glassy carbon electrode to prepare the working electrode-2, wherein the Ir loading on the electrode was at least 30 μg / cm³. 2 .

[0078] Comparative Example 4

[0079] The catalyst obtained in Comparative Example 2 was used as a raw material and dispersed together with perfluorosulfonic acid resin, propanol, and H2O in a homogenizer to form a mixed slurry. This slurry was then coated onto a glassy carbon electrode to prepare the working electrode-3, wherein the Ir loading on the electrode was at least 30 μg / cm³. 2 .

[0080] Comparative Example 5

[0081] The catalysts from Comparative Examples 1-2 were prepared into mixed slurries according to the method described in Example 4, denoted as Slurry 1-B and Slurry 2-B, respectively. Anode catalyst layers were then prepared by spraying using these mixed slurries as raw materials, wherein the PtRu loading was 0.1 mg / cm³. 2 The Ir loading was 50 μg / cm³. 2 The cathode catalyst layer was prepared using 60 wt% Pt / C, with a Pt loading of 0.3 mg / cm³. 2 Finally, catalytic membrane electrode 1-B and catalytic membrane electrode 2-B were obtained.

[0082] The working electrodes obtained in Example 4, Comparative Example 3, and Comparative Example 4 were subjected to OER tests. The working electrode used was a glassy carbon electrode with a Pt wire as the counter electrode and a catalyst supported on it (30 μg / cm³). 2An Ag / AgCl electrode was used as the reference electrode, and the electrolyte was 0.5M H₂SO₄ saturated with N₂. First, a positive linear scan (50 scans) was performed within the potential window of 0-1.0 V vs RHE at a scan rate of 50 mV / s to activate the working electrode. Then, a positive linear scan was performed within the potential window of 1.0-1.8 V vs RHE at a scan rate of 10 mV / s and a rotation speed of 1600 rpm to obtain the OER curve of the catalyst. Figure 3 As shown: The OER performance of the working electrode in Example 4 is much higher than that in Comparative Examples 3-4. This may be because the catalyst used in Comparative Example 3 has severe noble metal agglomeration, resulting in reduced Ir utilization. The catalyst used in Comparative Example 4 is obtained through physical dispersion, which leads to uneven distribution of noble metals, possibly causing the Ir on the actual working electrode to be less than 30 μg / cm³. 2 This causes a decrease in the OER performance of the catalyst.

[0083] Anti-reverse polarization tests were conducted on the catalytic membrane electrodes 1-A, 2-A, and 3-A prepared in Example 5, as well as the catalytic membrane electrodes 1-B and 2-B obtained in Comparative Example 5. Specific experimental parameters were as follows: anode hydrogen flow rate: 1 s / 1 pm; cathode air flow rate: 1 s / 1 pm; test temperature: 75°C; relative humidity: 100% RH for both anode and cathode; test pressure: atmospheric pressure. After the fuel cell activation and IV polarization test were completed, an external 0.2 A / cm² polarization was applied. 2 A constant current source with a current density of [value missing] was used to maintain the H2 / Air state until the voltage stabilized. Then, the anode H2 was switched to N2 to simulate the reverse polarity condition caused by insufficient anode H2. -1.5V was set as the cutoff voltage. When the battery voltage dropped below -1.5V, the constant current source stopped working, i.e., the reverse polarity ended. The period during which the voltage began to drop sharply to the end of the reverse polarity was considered the anti-reverse polarity time. The single-shutdown reverse polarity curve was obtained, as shown below. Figure 4 As shown, from Figure 4 It can be seen that, under the same precious metal loading, the single-shutdown reverse polarity time of the catalytic membrane electrode in Example 4 is much higher than that of the catalytic membrane electrode in Comparative Example 5. This indicates that the catalytic membrane electrode prepared by the method of the present invention can significantly improve the utilization rate of precious metals, thereby improving the reverse polarity resistance of fuel cells.

[0084] The IV curves after reverse polarity testing were used to compare the performance loss of the membrane electrode before and after reverse polarity. After one shutdown and reverse polarity test, the performance of the catalytic membrane electrode in Example 5 remained essentially unchanged. However, the performance of the comparative example decreased sharply, which may be due to factors such as uneven distribution of active components in the anode catalyst layer, resulting in local corrosion of the carbon support material and loss of PtRu and IrO2.

[0085] After the IV polarization test, the catalytic membrane electrodes obtained in Example 5 and Comparative Example 5 were further tested for their resistance to CO poisoning. The specific test method was as follows: the anode gas was switched from H2 to H2 + 10ppm CO (continuously passed for 1 hour), and the IV polarization test was performed to compare the performance differences of the fuel cells before and after the feed contained CO impurities. The obtained parameter data are summarized in Table 1.

[0086] Table 1 is a summary table of the performance data of each catalytic membrane electrode in Example 5 and Comparative Example 5.

[0087]

[0088] The catalyst slurry in Example 4 and Comparative Example 4 were subjected to wall adhesion experiments, respectively. Figure 5 The figure shows the wall-mounted experiment diagram. As can be seen from the figure, the catalyst slurry in Example 4 is more evenly dispersed.

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a proton exchange membrane fuel cell anti-reverse anode catalyst, characterized in that, Includes the following steps: S1: Preparation of Ir / C: Carbon support, iridium metal precursor and reducing alcohol are added to alkaline solution and uniformly dispersed to obtain a mixed slurry. After heating and reflux reaction, the pH value of the mixed slurry is adjusted to acidic. Finally, Ir / C is obtained by washing and filtration. S2: Preparation of IrO2 / C: The Ir / C is heat-treated by passing it through a N2 / O2 mixture to obtain IrO2 / C; S3: Preparation of PtRu-IrO2 / C: Pt metal precursors and Ru metal precursors are mixed with IrO2 / C, and a reducing agent is added to react and obtain PtRu-IrO2 / C. The PtRu-IrO2 / C includes a support and Pt-Ru alloy and IrO2 supported on the support. The support is a carbon material support. In the anti-reverse anode catalyst, the particle size of Pt-Ru alloy and IrO2 is maintained between 3-5 nm.

2. The method for preparing the anti-reverse anode catalyst for proton exchange membrane fuel cells according to claim 1, characterized in that, The total mass ratio of the Pt-Ru alloy to the mass of Ir is 4:1-4:

3.

3. The method for preparing the anti-reverse anode catalyst for proton exchange membrane fuel cells according to claim 1, characterized in that, In the Pt-Ru alloy, the mass ratio of Pt to Ru is 4:1 to 4:

3.

4. The method for preparing the anti-reverse anode catalyst for proton exchange membrane fuel cells according to claim 1, characterized in that, In step S1, the carbon support is a graphitized carbon material.

5. The method for preparing the anti-reverse anode catalyst for proton exchange membrane fuel cells according to claim 1, characterized in that, In step S1, the reducing alcohol includes any one of methanol, ethanol, ethylene glycol, propanol, and glycerol.

6. The method for preparing the anti-reverse anode catalyst for a proton exchange membrane fuel cell according to claim 1, characterized in that, In step S1, the reflux temperature range is 140-180℃.

7. The method for preparing the anti-reverse anode catalyst for proton exchange membrane fuel cells according to claim 1, characterized in that, In step S1, the reflux reaction time is 1-3 hours.

8. The method for preparing the anti-reverse anode catalyst for a proton exchange membrane fuel cell according to claim 1, characterized in that, The iridium metal precursor is either chloroiridic acid or iridium trichloride.

9. The method for preparing the anti-reverse anode catalyst for a proton exchange membrane fuel cell according to claim 1, characterized in that, The mass fraction of iridium in Ir / C is 20-40%.

10. The method for preparing the anti-reverse polarity anode catalyst according to claim 1, characterized in that, In step S2, the O2 content accounts for 20%-40% of the volume of the mixed gas.

11. The method for preparing the anti-reverse polarity anode catalyst according to claim 1, characterized in that, In step S2, the heat treatment temperature is 300-550℃; the heat treatment time is 1-3 hours.

12. A fuel cell anti-reverse anode catalyst slurry, characterized in that, The anode catalyst slurry includes the anti-reverse anode catalyst PtRu-IrO2 / C prepared by the preparation method described in claim 1, and also includes perfluorosulfonic acid resin, propanol, and deionized water. The PtRu-IrO2 / C, perfluorosulfonic acid resin, propanol, and deionized water are mixed in proportion and then homogenized to obtain a mixed slurry, which is the anode catalyst slurry.

13. A fuel cell, characterized in that, The anode catalyst layer in the fuel cell includes at least one anode catalyst layer prepared from the anti-reverse anode catalyst slurry as described in claim 12.

Images