A platinum-based fuel cell catalyst of intermetallic phase and its preparation method and application

Abstract

The present application relates to the technical field of fuel cell catalyst, in particular to an intermetallic phase platinum-based fuel cell catalyst and its preparation method and application. The preparation method comprises the following preparation steps: adding platinum precursor, cobalt precursor, zinc precursor, reducing agent and carbon carrier into alcohol liquid, uniformly ultrasonic dispersing to obtain mixed liquid A; under stirring, the mixed liquid A is subjected to first heating treatment, and after reaction, it is cooled to room temperature to obtain mixed liquid B; the mixed liquid B is subjected to solid-liquid separation, the solid residue is washed and dried; the dried sample is subjected to second heating treatment under a protective atmosphere, and the catalyst is obtained. The catalyst prepared by the method has the advantages of small nanoparticle size, high catalytic activity and good stability; the reaction raw materials are widely sourced, the added reducing agent is easy to remove, the preparation process is simple, the production efficiency is high, the cost is low, the prepared catalyst has high catalytic activity and good stability in hydrogen fuel cell, and has good mass production potential.

Description

Technical Field

[0001] This invention relates to the field of fuel cell catalyst technology, and in particular to a platinum-based fuel cell catalyst with an intermetallic phase, its preparation method, and its application. Background Technology

[0002] Hydrogen energy, as an absolutely clean new energy source, is also considered one of the ultimate solutions to carbon emissions. Its advantages, such as environmental friendliness, ease of storage and transportation, and high energy conversion efficiency, have garnered widespread attention worldwide. Hydrogen fuel cells can convert chemical energy into electrical energy through the chemical reaction between hydrogen and oxygen, and are considered an important means of solving environmental pollution and the energy crisis.

[0003] As a crucial part of the hydrogen energy society's development, the most critical issue in the development of fuel cell devices (proton exchange membrane fuel cells) is improving their performance. Closely related to performance is the membrane electrode assembly (MEA) in the fuel cell, whose output efficiency largely depends on the catalysts at both ends of the fuel cell, especially the oxygen reduction catalyst in the cathode, which reacts relatively slowly.

[0004] Given current research, catalysts in membrane electrode assemblies are mainly platinum and platinum-based materials. Scientists have further improved the performance of catalysts by designing platinum-based materials with different morphologies, structures and compositions. However, most catalysts only exhibit good catalytic ability on rotating disk electrodes, and their performance in actual battery devices (i.e., the membrane electrode performance of proton exchange membrane fuel cells) still cannot meet market requirements.

[0005] Currently reported platinum-based catalysts often require the introduction of surfactants during synthesis. These surfactants play a crucial role in synthesizing catalyst materials with specific morphologies (which in turn affect catalytic activity). However, these surfactants are difficult to remove subsequently, often adhering tightly to the catalyst and resulting in poor performance. Furthermore, removing these surfactants increases the cost of the preparation process, hindering large-scale production and commercialization. For example, prolonged heating and acid washing are required to remove surfactants. Specifically, using oleylamine surfactants requires prior heating and acid washing followed by heating in a tube furnace for removal. Similarly, polyvinylpyrrolidone surfactants are difficult to remove through acid washing and heating alone; high-temperature heating can also damage the synthesized catalyst material, and the surfactant may not be completely removed. Moreover, due to the high cost of platinum-based materials, currently reported platinum-based materials suffer from drawbacks such as high platinum content and poor stability in fuel cells, limiting their commercial application.

[0006] In addition, existing research has shown that introducing nickel and cobalt metals into platinum-based catalysts to prepare platinum-nickel matrix catalysts and preparing them as intermetallic phases can improve the activity and stability of the catalysts. However, obtaining such platinum-nickel and platinum-cobalt intermetallic phases usually requires high-temperature calcination, which will cause the particle size of nanoparticles to increase, thus adversely affecting the catalytic activity and catalytic effect of the catalyst.

[0007] Therefore, developing a method for preparing platinum-based catalysts with high catalytic activity and good stability on a large scale and in batches is of significant market value and strategic importance for the development of fuel cell catalysts. Summary of the Invention

[0008] To address the shortcomings of the existing technology mentioned in the background section, this invention provides a method for preparing a platinum-based fuel cell catalyst with an intermetallic phase, the technical solution of which is as follows:

[0009] Platinum precursor, cobalt precursor, zinc precursor, reducing agent, and carbon support are added to an alcoholic liquid and ultrasonically dispersed to obtain mixture A.

[0010] Under stirring, mixture A was subjected to a first heating treatment, and after the reaction was cooled to room temperature to obtain mixture B;

[0011] Mixture B was subjected to solid-liquid separation, and the solid residue was washed and dried.

[0012] The dried sample is then subjected to a second heat treatment under a protective atmosphere to obtain the final product.

[0013] In some embodiments, the molar ratio of the platinum precursor to the cobalt precursor is 1:(0.5-1); the molar ratio of the platinum precursor to the zinc precursor is 1:(0.25-1); the molar ratio of the platinum precursor to the reducing agent is 1:(1-7); and the molar ratio of the platinum precursor to the carbon support is 1:(12-20).

[0014] In some embodiments, the alcohol solvent is one or more combinations of triethylene glycol, benzyl alcohol, and glycerol.

[0015] In some embodiments, the platinum precursor is one or more combinations of tetraammonium platinum nitrate, platinum acetylacetonate, and chloroplatinic acid; the cobalt precursor is one or more combinations of cobalt acetate, cobalt formate, cobalt chloride, and cobalt acetylacetonate; the zinc precursor is one or more combinations of zinc chloride, zinc sulfate, and zinc acetylacetonate; the reducing agent is one or more combinations of glucose, ascorbic acid, ribose, and phloroglucinol; the carbon support is one or more combinations of Vulcan XC 72R carbon powder, carbon nanotubes, Ketjen Black 300, and Ketjen Black 600, and the platinum loading of the platinum precursor on the carbon support is 5% to 50%.

[0016] In some embodiments, the ultrasonic dispersion time is 30 to 600 min.

[0017] In some embodiments, the heating temperature of the first heating treatment is 100–220°C, and the heating time is 2–20 h.

[0018] In some embodiments, the solid-liquid separation process is performed by centrifugation. After each centrifugation, the solid residue is washed with a washing solution, and the number of centrifugations is 1 to 9. The washing solution is one or a mixture of acetone, anhydrous ethanol, and acetic acid solution with a concentration of 0.5 to 3 mol / L. The final centrifugation is performed by washing with the acetic acid solution. The drying temperature of the drying process is 50 to 90°C, and the drying time is 0.5 to 15 hours.

[0019] In some embodiments, the protective atmosphere is one or more of argon, nitrogen, and a hydrogen-argon mixture; the heating temperature of the second heating treatment is 200–900°C; and the heating time can be 1–5 hours.

[0020] The present invention also provides a catalyst comprising a carbon support and metal nanoparticles dispersed and supported on the carbon support; wherein the metal nanoparticles comprise platinum, cobalt, and zinc; and the catalyst is prepared by the method described above for preparing a platinum-based fuel cell catalyst with an intermetallic phase.

[0021] The present invention also provides the application of the catalyst, which is used as a catalyst in an electrochemical oxygen reduction reaction, or the catalyst is used as a catalyst in a membrane electrode assembly of a fuel cell; wherein the catalyst is prepared by the method for preparing a platinum-based fuel cell catalyst with an intermetallic phase as described above.

[0022] The method for preparing intermetallic platinum-based fuel cell catalysts provided by this invention has the following technical advantages compared with existing technologies:

[0023] The catalyst prepared by the method provided by the present invention comprises two parts: metal particles and catalyst support. It has advantages such as small nanoparticle size, high catalytic activity and good stability. The catalyst exhibits excellent performance in oxygen reduction reaction of rotating disk electrode and membrane electrode test.

[0024] This preparation method does not require the introduction of difficult-to-remove surfactants, the raw materials for the reaction are widely available, the added reducing agent is easy to remove, the preparation process is simple, the production efficiency is high, the cost is low, and the catalyst obtained has high catalytic activity and good stability in hydrogen fuel cells, with good mass production potential, thus having good practical application value.

[0025] Other features and beneficial effects of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects of the invention and other beneficial effects may be realized and obtained by means of the structures and / or components pointed out in the description and claims. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 The image shows the X-ray diffraction (XRD) pattern of the Zn-PtCo IMC / C catalyst prepared in Example 1.

[0028] Figure 2 Transmission electron microscopy (TEM) image of the Zn-PtCo IMC / C catalyst prepared in Example 1;

[0029] Figure 3 The linear sweep voltammetry (LSV) curve of the Zn-PtCo IMC / C catalyst prepared in Example 1 is shown.

[0030] Figure 4 The membrane electrode performance diagram is shown for the Zn-PtCo IMC / C catalyst prepared in Example 1.

[0031] Figure 5 Transmission electron microscope (TEM) images of comparative examples 1-4;

[0032] Figure 6 Linear sweep voltammetry (LSV) plots for Comparative Example 1 and Comparative Example 2;

[0033] Figure 7Linear sweep voltammetry (LSV) plots for Comparative Examples 3 and 4;

[0034] Figure 8 The images show transmission electron microscopy (TEM) and X-ray diffraction (XRD) patterns of the catalyst prepared in Example 2. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0036] The present invention also provides the following embodiments and comparative examples to verify the beneficial effects of the present invention:

[0037] Example 1

[0038] A method for preparing a platinum-based fuel cell catalyst with an intermetallic phase is provided, comprising the following steps:

[0039] S1. Weigh 1g of platinum acetylacetonate (2.543mmol, 1eq), 0.84g of cobalt acetylacetonate (2.358mmol, 0.927eq), 0.25g of zinc acetylacetonate (0.948mmol, 0.373eq), 1.1g of ascorbic acid (6.246mmol, 2.4564eq), and 0.5g of Ketjen Black 300 carbon powder (41.667mmol, 16.387eq), and place them in a reaction flask containing 50mL of benzyl alcohol;

[0040] S2. Place the container in an ultrasonic environment and sonicate for 120 minutes until the dispersion is uniform.

[0041] S3. After ultrasonic homogenization, the reaction vessel is transferred to a heating device for stirring and heating reaction. The reaction temperature is 190℃ and the reaction time is 10h.

[0042] S4. After the reaction apparatus has cooled to room temperature, first wash it 4 times by centrifugation with a mixed solvent of anhydrous ethanol and acetone (V ethanol / V acetone = 1 / 9), then wash it 3 times by centrifugation with 1 mol / L acetic acid solution, and then dry the catalyst in a vacuum drying oven at 70°C for 10 hours.

[0043] S5. The dried sample was heat-treated in argon at 650°C for 2 hours to obtain the final catalyst, which was recorded as the sample of Example 1, with a yield of 1.1g.

[0044] Example 2

[0045] Based on Example 1, the mass of zinc acetylacetone was changed to 0.5 g (1.897 mmol, 0.746 eq), and the resulting sample was recorded as the Sample of Example 2.

[0046] Comparative Example 1

[0047] Without adding a reducing agent, the sample obtained in Example 1 was designated as Comparative Example 1. The other preparation processes and conditions for this comparative example were the same as in Example 1.

[0048] Comparative Example 2

[0049] Without adding a zinc precursor, the sample obtained in Example 1 was designated as Comparative Example 2. The other preparation processes and conditions for this comparative example were the same as in Example 1.

[0050] Comparative Example 3

[0051] The only difference between this comparative example and Example 1 is that the amount of zinc precursor used is 0.2 eq, which is 0.134 g, or 0.5083 mmol (below the limit specified in this application); the resulting sample is designated as Comparative Example 3. The other preparation processes and conditions of this comparative example are the same as those of Example 1.

[0052] Comparative Example 4

[0053] The only difference between this comparative example and Example 1 is that the amount of zinc precursor used is 3.8145 mmol, which is 1.0055 g, 1.5 eq (exceeding the limits of this application); the resulting sample is designated as Comparative Example 4. The other preparation processes and conditions of this comparative example are the same as those of Example 1.

[0054] The catalyst products produced in the examples and comparative examples were subjected to performance tests, and the test results are as follows:

[0055] 1. Product particle size and elemental distribution:

[0056] (1) Sample of Example 1

[0057] like Figure 1 As shown in Figure 2, powder diffraction (XRD) reveals that the diffraction peaks of the nanoparticle Zn-PtCoIMC / C catalyst synthesized in Example 1 correspond to the intermetallic phase of PtCo (No. 43-1358), and the nanoparticles are small in size and all remain between 2.5 nm and 5.5 nm.

[0058] (2) Sample of Example 2

[0059] Figure 8 Here are the TEM and XRD patterns of the sample from Example 2. Figure 8As can be seen from A, when the amount of Zn in Example 2 is doubled compared to Example 1, the particle size of the catalyst prepared in Example 2 is about 5 nm, and its XRD pattern ( Figure 8 B) can also correspond well to the intermetallic phase of PtCo.

[0060] (3) Comparative Examples 1-4

[0061] Figure 5 The A and D images are TEM images of the comparative examples 1-4, respectively. As can be seen from the images, compared with the samples of Examples 1-2, the particle uniformity of Comparative Example 1 is significantly worse, and the particle size is larger, with a particle size of about 8-20 nm; the particle size of Comparative Example 2 is larger, with a particle size of about 6-20 nm; the particle size of Comparative Example 3 is larger, with a particle size of about 5-16 nm; and the particle size of Comparative Example 4 is larger, with a particle size of about 5-10 nm.

[0062] 2. Linear sweep volt-ampere (LSV) curve and half-wave potential:

[0063] Linear sweep voltammetry (LSV) curves of the products and the corresponding half-wave potentials for each catalyst were obtained. The test conditions were as follows: in 0.1 M HClO4, the scan potential range was 0.05–1.26 V vs. RHE, and the scan rate was 0.05 V s⁻¹, resulting in the catalyst CV curve, which showed a clear hydrogen region. The LSV curves were tested in oxygen-saturated 0.1 M HClO4, with a rotating disk electrode speed of 1600 rpm. The LSV data collection range was 0–1.1 V (vs. RHE), and the catalyst test data was obtained using a scan rate of 0.05 V s⁻¹.

[0064] (1) Sample of Example 1

[0065] Figure 3 The image shows the linear sweep voltammetry (LSV) curve for the sample in Example 1. The LSV curve shows that the initial half-wave potential of the sample in Example 1 is 0.905 V vs. RHE, and the mass activity is 0.68 A mg. -1 (The Pt loading on the electrode is 2 μg, and the electrode area is 0.196 cm²) 2 This indicates that the catalyst has good oxygen reduction performance.

[0066] (2) Comparative Examples 1-2

[0067] Figure 6The linear sweep voltammetry (LSV) curves for Comparative Examples 1 and 2 show that the half-wave potentials in the initial LSV curves of Comparative Examples 1 and 2 are 0.896V vs. RHE and 0.898V vs. RHE, respectively. Compared with the examples, the half-wave potential values ​​are lower, indicating that the oxygen reduction performance of their catalyst samples is worse.

[0068] (2) Comparative Examples 3-4

[0069] Figure 7 The linear sweep voltammetry (LSV) curves for Comparative Examples 3 and 4 show that the half-wave potentials in the initial LSV curves of Comparative Examples 3 and 4 are 0.885V vs. RHE and 0.854V vs. RHE, respectively. Compared with the examples, the half-wave potential values ​​are lower, indicating that the oxygen reduction performance of their catalyst samples is worse.

[0070] 4. Membrane performance testing

[0071] The membrane performance of the products from the examples and comparative examples in a proton exchange membrane fuel cell was tested. The test conditions were as follows: the test was conducted under hydrogen-air conditions, with both hydrogen and air pressures at 100 kPa, and the membrane electrode area was 25 cm². 2 The catalyst used at the anode was a commercial Pt / C (40%, TKK), and the catalyst used at the cathode was the product of the examples or comparative examples. The total amount of platinum used in the cathode and anode catalysts was 0.3 mg / cm³. -2 The test temperature was 80℃ and the relative humidity was 100%.

[0072] (1) Sample of Example 1

[0073] Figure 4 For the membrane performance testing of the sample in Example 1 in a proton exchange membrane fuel cell, such as... Figure 4 As shown, the membrane electrode is at 1.5 A cm⁻¹ -2 The output power at that location is 0.97W cm. -2 The power at 0.6V can reach 1.1W cm -2 Peak power can reach 1.19W cm -2 This demonstrates the excellent battery performance of this catalyst.

[0074] The membrane electrode performance test results of the sample in Example 1 of this invention in a proton exchange membrane fuel cell show that its catalyst has excellent battery performance and can output high battery power, which is close to the actual application scenario. This indicates that it performs well in actual battery devices and can meet the requirements of market applications.

[0075] 5. Stability

[0076] Figure 3 The stability test of the sample in Example 1 on the rotating disk electrode is also shown. After 30,000 cycles, the half-wave potential of the sample in Example 1 only decreased by 13mV, showing its good stability and excellent application prospects.

[0077] Specific implementation examples and comparative test results are shown in Table 1 below:

[0078] Table 1

[0079]

[0080]

[0081] The uniformity of the catalyst product particle size was determined by visual observation under a microscope: a sample of the catalyst product was placed under a microscope for magnified observation, which revealed the uniformity of the particle size of the products in each embodiment and comparative example.

[0082] Analysis of the data in Table 1 shows that:

[0083] (1) The catalyst product prepared in the embodiments of the present invention has small nanoparticle size, and as can be seen from the half-wave potential data, membrane performance test data and stability performance test data, it has advantages such as high catalytic activity and good stability. The catalyst exhibits excellent performance in the oxygen reduction reaction of the rotating disk electrode and in the membrane electrode test.

[0084] (2) In Comparative Example 1, no reducing agent was introduced during the preparation process, resulting in unevenness of the catalyst's metal particles. Compared to the embodiments of the present invention, the particle uniformity of the product in Comparative Example 1 decreased, and its catalytic ability was reduced. The reason for this is:

[0085] Reducing agents affect the size and morphology of catalyst products. Without a reducing agent, the resulting catalyst will have poor morphological regularity. In the process of rare-earth-doped platinum-cobalt alloys, the limited reduction capacity of the preparation process without a reducing agent leads to uneven metal particle size, with larger particles exposing less active surface area, resulting in a decrease in catalytic activity.

[0086] (3) Compared with the embodiments of the present invention, Comparative Example 2 does not introduce zinc, and the particle size of the catalyst product is increased, which leads to a decrease in the active area of ​​the catalyst and a decrease in its catalytic activity.

[0087] (4) Compared with the embodiments of the present invention, the zinc content introduced in Comparative Example 3 and Comparative Example 4 is lower or higher (outside the scope of the present invention); compared with the catalyst samples prepared in the embodiments of the present invention, the particle size of the samples of Comparative Example 3-4 is larger, the active area of ​​the catalyst is reduced, and the catalytic activity is reduced.

[0088] In summary, the method for preparing the intermetallic platinum-based fuel cell catalyst provided by this invention includes at least the following design concept, mechanism of action, and beneficial effects:

[0089] Design concept and mechanism of action

[0090] 1. The present invention incorporates zinc precursor, cobalt precursor, and reducing agent into the preparation of the catalyst:

[0091] Traditional Pt-based catalysts typically contain a high proportion of Pt in their nanomaterials, which limits their market application due to Pt's high cost. Introducing cobalt or nickel can reduce costs, and the synthesis of materials with intermetallic phases can significantly improve the catalyst's catalytic activity and stability. However, catalysts with platinum-cobalt or platinum-nickel intermetallic phases often experience particle size enlargement during high-temperature calcination, negatively impacting catalytic performance. The introduction of appropriate amounts of zinc can address these issues and also serves the following purposes:

[0092] First, the introduction of an appropriate amount of zinc atoms can effectively suppress particle growth. The introduction of zinc can reduce particle size. In addition, it can also prevent catalyst nanoparticles from growing larger during subsequent high-temperature treatment.

[0093] Secondly, during the catalyst preparation process, zinc volatilizes at high temperatures, giving the carbon material a porous structure. The chemical changes that zinc atoms undergo on the catalyst surface (including ordered atomic substitution doping and affecting the electronic structure of the catalyst surface) can alter the microenvironment on the catalyst surface and enhance the catalyst activity.

[0094] Furthermore, during the catalytic process, cobalt or nickel transition metals are prone to dissolution. These dissolved transition metal ions have a strong destructive effect on the proton exchange membrane, thereby affecting the device performance. An appropriate amount of zinc atoms partially replace some of the ordered cobalt atoms between platinum and cobalt metals during the material preparation process, forming a stable triangular structure with platinum and adjacent cobalt atoms, thus improving the stability of the catalyst.

[0095] Finally, during the high-temperature treatment, some zinc atoms from the high-temperature pyrolysis modify the support in the form of single atoms, which will further improve the stability of the catalyst.

[0096] 2. Based on the concept of zinc-doped platinum-cobalt alloys, a reducing agent is introduced during the preparation process. This reducing agent can control the nucleation and growth process of alloy nanoparticles and plays a role similar to coordination-controlled morphology. It has a significant impact on the size and morphology of the catalyst (the overall morphology of the catalyst and the distribution of metal particles on the carbon support), and the size and morphology of the catalyst product will affect its activity. Therefore, by introducing a reducing agent, the prepared catalyst has a more regular morphology. If a reducing agent is not added in the process of rare earth-doped platinum-cobalt alloys, the reduction capacity of the preparation process is limited, resulting in uneven metal particle size. Larger particles expose less active surface area, leading to a decrease in the catalyst's catalytic activity.

[0097] 3. Based on the preparation of catalysts by introducing zinc precursors, cobalt precursors, and reducing agents, this invention selects a specific alcohol solvent (preferably benzyl alcohol). Benzyl alcohol has the advantages of high boiling point, solubility for a wide variety of reaction precursors, moderate polarity, and exhibiting characteristics of both aqueous and oil phases. This solvent will not contaminate the reaction products, is easy to centrifuge and clean, and has characteristics similar to oil phase solvents, with high solubility for the reaction products and a wide range of precursors that can be dissolved. Due to its polarity, it can produce more products in less solvent during the synthesis process, greatly reducing production costs.

[0098] 4. In addition, existing basic research on platinum-based fuel cell catalysts often does not give much consideration to the feasibility of mass production. Only by achieving mass production can the requirements for catalyst commercialization be met. This also puts forward higher requirements for catalyst preparation, which must meet product consistency and achieve a simple and efficient synthesis method.

[0099] In the synthesis and preparation of existing platinum-based fuel cell catalysts, acid treatment of the high-temperature calcined catalyst is crucial. After acid treatment, more active sites will be exposed on the surface of the catalyst, thereby improving the catalytic activity. However, in the existing Pt-based catalyst preparation process, the product needs to be heated in acid for a long time (generally around 60℃-94℃, acid treatment for about 2-5 hours) to obtain a catalyst with high activity. This high-temperature carbonization consumes a lot of energy, and the acid washing process consumes a lot of time, which reduces production efficiency and increases production costs.

[0100] This invention, based on the introduction of zinc precursor, cobalt precursor, and reducing agent into catalyst preparation, utilizes a heated reaction to obtain a highly active catalyst. This catalyst can be obtained through simple centrifugal acid washing. Furthermore, the reducing agent is effectively removed during heating and acid washing. The entire process requires no surfactant, ensuring sufficient exposure of the active sites on the catalyst surface and guaranteeing good catalyst activity. In summary, this invention achieves a highly active catalyst through liquid-phase heating synthesis and simple acid washing. Compared to existing processes that involve prolonged heating and stirring of the catalyst in acid, this invention simplifies the acid washing process by rinsing the product after centrifugation, making it more convenient and cost-effective.

[0101] 5. Based on the introduction of zinc precursor, cobalt precursor and reducing agent into the preparation of catalyst, the present invention adopts specific raw material composition ratio control, especially the ratio control of zinc precursor and other raw materials, so that the prepared catalyst has advantages such as small particle size, high activity and good stability.

[0102] Beneficial effects:

[0103] 1. The catalyst Zn-PtCo IMC / C prepared by this invention is composed of PtCo nanoparticles with Zn doped intermetallic phase. The introduction of zinc can reduce the particle size. In addition, it can also prevent the particles from growing larger during subsequent high-temperature treatment. Compared with catalysts without appropriate zinc doping, the catalyst nanoparticles obtained by this preparation method are smaller in size and more uniformly distributed on the carbon support.

[0104] 2. In the catalyst prepared by this invention, appropriate Zn doping can not only change the electronic structure of the catalyst surface and improve the activity of the catalyst, but also Zn atoms can replace some Co atoms in the intermetallic PtCo, forming a triangular stable structure with Pt and adjacent Co atoms, thereby improving the stability of the catalyst.

[0105] 3. During the high-temperature treatment process, some Zn atoms modify the carbon support in the form of single atoms, further improving the stability of the catalyst.

[0106] 4. The catalyst prepared by this invention is synthesized by liquid phase method. 20 grams of catalyst can be prepared by each liter of benzyl alcohol solvent. Since benzyl alcohol solvent has a high boiling point and moderate polarity, it exhibits the characteristics of both aqueous and oil phases. Ten-gram level catalysts can be prepared by using less benzyl alcohol solvent, which greatly reduces the amount of solvent and has outstanding mass production potential.

[0107] 5. The catalyst prepared by this invention does not involve the addition of any surfactants, and the reducing agent can be removed and washed away during heating and acid washing. The catalyst surface has high cleanliness and high catalytic activity.

[0108] In summary, the catalyst prepared by the method provided in this invention has advantages such as small nanoparticle size, high catalytic activity, and good stability. The catalyst exhibits good performance in both rotating disk electrodes and proton exchange membrane fuel cell devices, indicating its promising performance in practical battery devices. The preparation method provided by this invention eliminates the need for difficult-to-remove surfactants, facilitates the removal of reducing agents, utilizes widely available reaction raw materials, has a simple preparation process, high production efficiency, and low cost, demonstrating good mass production potential and thus significant market application value.

[0109] It should be noted that:

[0110] In this article, “~” is used to represent the range of values, and the range of values ​​represented by this expression includes two endpoint values.

[0111] The specific parameters or some commonly used reagents or raw materials in the above embodiments are specific or preferred embodiments under the concept of the present invention, and are not intended to limit it; those skilled in the art can make adaptive adjustments within the concept and protection scope of the present invention.

[0112] In addition, unless otherwise specified, the raw materials used may be commercially available products in the field or prepared by conventional methods in the field; that is, the reagents and instruments used in this embodiment do not specify the manufacturer or other information, and are all conventional products that can be purchased from the market.

[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a platinum-based fuel cell catalyst with an intermetallic phase, characterized in that, The preparation steps include the following: Platinum precursor, cobalt precursor, zinc precursor, reducing agent, and carbon support are added to an alcohol solvent and ultrasonically dispersed to obtain mixture A. Under stirring, mixture A was subjected to a first heating treatment, and after the reaction was cooled to room temperature, mixture B was obtained; Mixture B was subjected to solid-liquid separation, and the solid residue was washed and dried. The dried sample is subjected to a second heat treatment under a protective atmosphere to obtain the catalyst; the catalyst includes a carbon support and metal nanoparticles dispersed and supported on the carbon support; the metal nanoparticles are Zn-doped intermetallic PtCo nanoparticles, and the size of the metal nanoparticles is 2.5 nm to 5.5 nm. Wherein, the molar ratio of the platinum precursor to the cobalt precursor is 1:(0.5-1); the molar ratio of the platinum precursor to the zinc precursor is 1:(0.25-1); the molar ratio of the platinum precursor to the reducing agent is 1:(1-7); and the molar ratio of the platinum precursor to the carbon support is 1:(12-20). The alcohol solvent is benzyl alcohol; The platinum precursor is one or more combinations of tetraammonium platinum nitrate, platinum acetylacetonate, and chloroplatinic acid. The cobalt precursor is one or more combinations of cobalt acetate, cobalt formate, cobalt chloride, and cobalt acetylacetonate. The zinc precursor is one or more combinations of zinc chloride, zinc sulfate, and zinc acetylacetonate. The reducing agent is one or more of ascorbic acid and phloroglucinol; The carbon support is one or more of Vulcan XC 72R carbon powder, carbon nanotubes, Ketjen Black 300, and Ketjen Black 600, and the loading of platinum in the platinum precursor on the carbon support is 5% to 50%. The ultrasonic dispersion time is 30–600 min; the heating temperature of the first heating treatment is 100–220℃, and the heating time is 2–20 h. The protective atmosphere is one or more of argon, nitrogen, and a hydrogen-argon mixture; the heating temperature of the second heating treatment is 200–900°C; and the heating time is 1–5 hours.

2. The method for preparing the intermetallic platinum-based fuel cell catalyst according to claim 1, characterized in that: The solid-liquid separation process is carried out by centrifugation. After each centrifugation, the solid residue is washed with a washing solution. The number of centrifugations is 1 to 9. The washing solution is one or a mixture of acetone, anhydrous ethanol, and acetic acid solution with a concentration of 0.5–3 mol / L; wherein, the final centrifugation process is performed using the acetic acid solution for washing. The drying temperature for the drying process is 50–90°C, and the drying time is 0.5–15 h.

3. A catalyst, characterized in that: The catalyst comprises a carbon support and metal nanoparticles dispersed and supported on the carbon support; the metal nanoparticles are Zn-doped intermetallic PtCo nanoparticles, and the size of the metal nanoparticles is 2.5 nm to 5.5 nm. The catalyst is prepared using the method for preparing a platinum-based fuel cell catalyst with an intermetallic phase as described in any one of claims 1-2.

4. The application of the catalyst, characterized in that: The catalyst is used as a catalyst in the electrochemical oxygen reduction reaction; The catalyst is prepared using the method for preparing intermetallic platinum-based fuel cell catalysts as described in any one of claims 1-2.

5. The application of the catalyst, characterized in that: The catalyst is used as a catalyst in the membrane electrode assembly of a fuel cell; The catalyst is prepared using the method for preparing intermetallic platinum-based fuel cell catalysts as described in any one of claims 1-2.

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