Pt-based high-entropy intermetallic compound oxygen reduction catalyst, preparation method and application
By preparing Pt-based high-entropy intermetallic compound catalysts, the problems of excessively large particle size and insufficient stability in existing technologies have been solved, achieving high-efficiency oxygen reduction catalytic performance and potential for fuel cell applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-30
- Publication Date
- 2026-03-10
AI Technical Summary
Existing Pt-based high-entropy alloy catalysts have excessively large particle sizes during the ordered transformation process, resulting in a significant reduction in the catalytic activity of the oxygen reduction reaction and insufficient stability, making it difficult to meet the high-efficiency application requirements of proton exchange membrane fuel cells.
Potassium chloroplatinate and transition metal precursor salts were ultrasonically dispersed in ethylene glycol using a preparation method. NaBH4 ice-water solution was added to form a precursor solution. After centrifugation, washing, and drying, the mixture was stirred under an argon atmosphere and finally heat-treated under a hydrogen atmosphere to form a small-particle-size and stable Pt-based high-entropy intermetallic compound catalyst.
The prepared Pt-based high-entropy intermetallic compound catalyst has a particle size of 3.4 nm, a half-wave potential as high as 0.913 V, and a specific activity of 0.38 A/mgPt, which significantly improves catalytic performance and stability, making it suitable for high-efficiency oxygen reduction reactions in proton exchange membrane fuel cells.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of proton exchange membrane fuel cell anode catalyst synthesis technology, and specifically relates to a Pt-based high-entropy intermetallic compound oxygen reduction catalyst, its preparation method, and its application. Background Technology
[0002] Proton exchange membrane fuel cells (PEMFCs) are considered a promising sustainable energy conversion system due to their high efficiency and environmental friendliness. Because the oxygen electrode reaction in the oxygen reduction reaction (ORR) has a very high overpotential, it is almost impossible to achieve rapid catalytic reduction of oxygen near the thermodynamic equilibrium potential. Therefore, increasing the rate of the oxygen reduction reaction is key to improving fuel cell efficiency.
[0003] Platinum (Pt) has become the most important catalyst in ORR electrocatalyst applications due to its significant catalytic effect. Currently, the mainstream Pt catalyst is the Pt / C catalyst, which achieves a specific activity of 0.1–0.12 A / mg under H2-O2 fuel cell testing conditions. Pt Compared to the 0.44A / mg figure proposed by the U.S. Department of Energy in 2017, Pt There is still a significant gap between the current performance and the target. Furthermore, the stability of Pt / C catalysts under ORR operating conditions is severely tested due to a series of factors, including Pt particle migration, agglomeration, dissolution, redeposition, and carbon support corrosion. Therefore, further improving the catalytic performance of the catalyst, reducing the loading of precious metals, and simultaneously enhancing the stability of the oxygen reduction catalyst will make PEMFC applications more competitive in the market.
[0004] High-entropy alloys (HEAs) were first reported as a novel functional material in 2004. Noble metal-based HEA nanoparticles have exhibited excellent catalytic performance in electrocatalysis. Near-equimolar mixtures of elements can produce unique properties such as the cocktail effect, high-entropy effect, lattice distortion effect, and slow diffusion effect, which are beneficial for improving the catalytic performance of noble metals and reducing the amount of noble metals used. Transforming disordered HEAs into ordered high-entropy intermetallic compounds can further enhance catalytic performance. However, the ordering transformation requires high-temperature heat treatment to overcome the energy barriers of atomic diffusion and ordering transformation, and it also leads to the agglomeration and growth of metal particles, preventing further improvement in apparent activity. In high-load platinum intermetallic (Pt IMC) catalysts for practical applications, high-density particles further exacerbate catalyst agglomeration, thereby significantly reducing the apparent electrocatalytic activity and Pt atom utilization efficiency.
[0005] Therefore, how to directly and efficiently prepare Pt-based high-entropy intermetallic compound oxygen reduction catalysts with high loading, small particle size, excellent performance and good stability is a key scientific and technological problem that urgently needs to be solved. Summary of the Invention
[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a Pt-based high-entropy intermetallic compound oxygen reduction catalyst, its preparation method, and its application, in order to solve the problem that the particle size of high-load Pt-based high-entropy alloy catalysts is too large during the ordered transformation process, which significantly reduces the catalytic activity of the oxygen reduction reaction.
[0007] To achieve the above and other related objectives, this invention provides a method for preparing a Pt-based high-entropy intermetallic compound oxygen reduction catalyst, the method comprising the following steps:
[0008] S1. Dissolve potassium chloroplatinate in ethylene glycol and disperse it by ultrasonication to form the first precursor solution;
[0009] S2. The transition metal precursor salt and carbon support are ultrasonically dispersed in ethylene glycol to obtain a second precursor solution; the transition metal precursor salt includes a combination of at least four transition metal precursor salts selected from Co, Ni, Cu, Zn, Ga, Bi, Pb, Sn, and In precursor salts.
[0010] S3. Mix the first precursor solution and the second precursor solution, blow argon gas under sonication, and add NaBH4 ice water solution dropwise. After sonication for a period of time, the first product dispersion is obtained; the molar ratio of Pt element to transition metal element in the first product dispersion is 1:1 to 4:1.
[0011] S4. The first product dispersion is centrifuged, washed, dried and then ground to obtain Pt-based high-entropy alloy precursor powder.
[0012] S5. Weigh a certain amount of potassium chloride platinum oxide and dissolve it in ethylene glycol to form a dispersion. Add the Pt-based high-entropy alloy precursor powder to the dispersion and ultrasonically disperse it to obtain a Pt-based high-entropy alloy precursor dispersion. Then, place the Pt-based high-entropy alloy precursor dispersion under an argon atmosphere and stir to obtain a second product dispersion.
[0013] S6. The second product dispersion is centrifuged, washed, vacuum dried and then ground to obtain a Pt-rich high-entropy alloy precursor powder.
[0014] S7. The surface-rich Pt high-entropy alloy precursor powder is heat-treated in a hydrogen atmosphere to obtain a Pt-based high-entropy intermetallic compound.
[0015] Preferably, the ultrasound duration in step S1 is 1 to 4 hours.
[0016] Preferably, the transition metal precursor salt in step S2 is one or a combination of a transition metal chloride, nitrate, acetate, or acetylacetonate.
[0017] Preferably, the carbon support in step S2 is one of XC-72, XC-72R, EC-300J, and EC-600J.
[0018] Preferably, in step S2, the ratio between the total mass of the transition metal in the second precursor solution and the mass of the carbon support is 3:7 to 6:4.
[0019] Preferably, the ultrasonic dispersion time in step S2 is 1 to 5 hours.
[0020] Preferably, the molar ratio between NaBH4 in the NaBH4 ice-water solution and the transition metal element in the second precursor solution in step S3 is 5:1 to 20:1.
[0021] Preferably, the dropping rate of the NaBH4 ice-water solution in step S3 is 1 to 5 mL / min.
[0022] Preferably, the ultrasound time in step S3 is 15 to 60 minutes.
[0023] Preferably, the centrifugation speed in step S4 is 8000-10000 rpm, and the centrifugation time is 5-10 min.
[0024] Preferably, the washing in step S4 involves washing with anhydrous ethanol 3 to 5 times, followed by washing with deionized water.
[0025] Preferably, the vacuum drying temperature in step S4 is 40–80°C, and the vacuum drying time is 6–24 hours.
[0026] Preferably, the molar ratio of Pt element in the dispersion to transition metal element in the first product dispersion in step S5 is 1:1 to 1:6.
[0027] Preferably, before the Pt-based high-entropy alloy precursor dispersion is mixed and stirred under an argon atmosphere in step S5, a pretreatment step is further included, specifically, the Pt-based high-entropy alloy precursor dispersion is kept under vacuum for 15 to 30 minutes.
[0028] Preferably, the mixing and stirring time in step S5 is 6h to 24h.
[0029] Preferably, the centrifugation speed in step S6 is 8000-10000 rpm, and the centrifugation time is 5-10 min.
[0030] Preferably, the washing in step S6 involves washing with anhydrous ethanol 3 to 5 times, followed by washing with deionized water.
[0031] Preferably, the vacuum drying temperature in step S6 is 40–80°C, and the vacuum drying time is 6–24 hours.
[0032] Preferably, the heat treatment temperature in step S7 is 300℃~500℃, and the heat treatment time is 2h~6h.
[0033] The present invention also provides a Pt-based high-entropy intermetallic compound oxygen reduction catalyst, wherein the Pt-based high-entropy intermetallic compound oxygen reduction catalyst is prepared by the above-described preparation method of the Pt-based high-entropy intermetallic compound oxygen reduction catalyst.
[0034] In addition, the present invention also provides an application of a Pt-based high-entropy intermetallic compound oxygen reduction catalyst, wherein the Pt-based high-entropy intermetallic compound oxygen reduction catalyst is applied in the oxygen reduction reaction catalysis process, and wherein the Pt-based high-entropy intermetallic compound oxygen reduction catalyst is prepared by the above-described preparation method of the Pt-based high-entropy intermetallic compound oxygen reduction catalyst.
[0035] As described above, the Pt-based high-entropy intermetallic compound oxygen reduction catalyst, its preparation method, and its application of the present invention have the following advantages:
[0036] Beneficial effects:
[0037] This invention lowers the ordering transition temperature by adding low-melting-point elements to a high-entropy alloy, forming an ordered structure at 300℃. The prepared Pt-based high-entropy intermetallic compound has a particle size of only 3.4 nm. By modulating the electronic structure of Pt using non-noble metals, the intrinsic activity of Pt is improved, achieving better catalytic performance with a smaller Pt loading. Furthermore, the prepared Pt-based high-entropy intermetallic compound oxygen reduction catalyst exhibits excellent performance in electrocatalytic oxygen reduction, with a half-wave potential as high as 0.913 V and a specific activity of 0.38 A / mg. Pt Its specific surface area activity reaches 0.52 mA / cm². 2 . Attached Figure Description
[0038] Figure 1 The diagram shown is a process flow chart of the preparation method of Pt-based high-entropy intermetallic compound oxygen reduction catalyst in a specific embodiment of the present invention.
[0039] Figure 2a The image shown is the XRD pattern of the PtCoNiZnGa high-entropy intermetallic compound oxygen reduction catalyst prepared in Example 1 of this invention.
[0040] Figure 2b The image shown is a TEM image of the PtCoNiZnGa high-entropy intermetallic compound oxygen reduction catalyst prepared in Example 1 of this invention.
[0041] Figure 2c The image shown is an HRTEM image of the PtCoNiZnGa high-entropy intermetallic compound oxygen reduction catalyst prepared in Example 1 of this invention.
[0042] Figure 2d The image shows the particle size distribution of the PtCoNiZnGa high-entropy intermetallic compound oxygen reduction catalyst prepared in Example 1 of this invention.
[0043] Figure 2e The image shown is an EDS surface distribution diagram of the PtCoNiZnGa high-entropy intermetallic compound oxygen reduction catalyst prepared in Example 1 of this invention.
[0044] Figure 3a The image shown is the XRD pattern of the PtCoNiCuGa high-entropy intermetallic compound oxygen reduction catalyst prepared in Example 2 of this invention.
[0045] Figure 3b The image shown is a TEM image of the PtCoNiCuGa high-entropy intermetallic compound oxygen reduction catalyst prepared in Example 2 of this invention.
[0046] Figure 3c The image shown is an HRTEM image of the PtCoNiCuGa high-entropy intermetallic compound oxygen reduction catalyst prepared in Example 2 of this invention.
[0047] Figure 3d The diagram shows the particle size distribution of the PtCoNiCuGa high-entropy intermetallic compound oxygen reduction catalyst prepared in Example 2 of this invention.
[0048] Figure 4a The image shown is the XRD pattern of the PtCoNiCuSn high-entropy intermetallic compound oxygen reduction catalyst prepared in Example 3 of this invention.
[0049] Figure 4b The image shown is a TEM image of the PtCoNiCuSn high-entropy intermetallic compound oxygen reduction catalyst prepared in Example 3 of this invention.
[0050] Figure 4c The image shown is an HRTEM image of the PtCoNiCuSn high-entropy intermetallic compound oxygen reduction catalyst prepared in Example 3 of this invention.
[0051] Figure 4d The image shows the particle size distribution of the PtCoNiCuSn high-entropy intermetallic compound oxygen reduction catalyst prepared in Example 3 of this invention.
[0052] Figure 5aThe figure shows a comparison of the electrochemical oxygen reduction reaction cyclic voltammetry (CV) tests of the test electrodes made with the catalysts in Experimental Example 1 and Experimental Example 2 of this invention.
[0053] Figure 5b The graph shows a comparison of the linear sweep voltammetry (LSV) tests of the electrochemical oxygen reduction reaction on the test electrodes made with the catalysts in Experimental Examples 1 and 2 of this invention.
[0054] Figure 5c The diagram shows the mass-to-specific activity and specific surface area activity of the PtCoNiZnGa high-entropy intermetallic compound oxygen reduction catalyst prepared in Example 1 of this invention.
[0055] Figure 5d The figure shown is a comparison of cyclic voltammetry (CV) tests after the stability test of the test electrode made of PtCoNiZnGa catalyst in Experimental Example 3 of this invention.
[0056] Figure 5e The image shows a comparison of linear sweep voltammetry (LSV) tests after cyclic testing of the test electrode made of PtCoNiZnGa catalyst in Experimental Example 3 of this invention.
[0057] Figure 6 The diagram shows the application performance of the PtCoNiZnGa high-entropy intermetallic compound oxygen reduction catalyst in a fuel cell in Application Example 1 of this invention. Detailed Implementation
[0058] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.
[0059] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the respective manufacturers.
[0060] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention, any prior art methods, apparatus, and materials similar to or equivalent to those described, apparatus, and materials in the embodiments of this invention may be used to implement the present invention.
[0061] See Figure 1 This invention provides a method for preparing a Pt-based high-entropy intermetallic compound oxygen reduction catalyst, the method comprising the following steps:
[0062] S1. Dissolve potassium chloroplatinate in ethylene glycol and disperse it by ultrasonication to form the first precursor solution;
[0063] S2. The transition metal precursor salt and carbon support are ultrasonically dispersed in ethylene glycol to obtain a second precursor solution; the transition metal precursor salt includes a combination of at least four transition metal precursor salts selected from Co, Ni, Cu, Zn, Ga, Bi, Pb, Sn, and In precursor salts.
[0064] S3. Mix the first precursor solution and the second precursor solution, blow argon gas under sonication, and add NaBH4 ice water solution dropwise. After sonication for a period of time, the first product dispersion is obtained. The molar ratio of Pt element to transition metal element in the first product dispersion is 1:1 to 4:1.
[0065] S4. The first product dispersion is centrifuged, washed, dried and then ground to obtain Pt-based high-entropy alloy precursor powder.
[0066] S5. Weigh out a certain amount of potassium chloride platinum oxide and dissolve it in ethylene glycol to form a dispersion. Add Pt-based high-entropy alloy precursor powder to the dispersion and ultrasonically disperse it to obtain a Pt-based high-entropy alloy precursor dispersion. Then, place the Pt-based high-entropy alloy precursor dispersion under an argon atmosphere and stir to obtain a second product dispersion.
[0067] S6. The second product dispersion is centrifuged, washed, vacuum dried and then ground to obtain a Pt-rich high-entropy alloy precursor powder.
[0068] S7. Heat-treat the Pt-rich high-entropy alloy precursor powder under a hydrogen atmosphere to obtain a Pt-based high-entropy intermetallic compound.
[0069] Specifically, in step S3, the molar ratio of Pt to transition metal in the first product dispersion can be any value within a range such as 1:1, 1:2, 1:3, or 1:4. Additionally, the second addition of potassium chloroplatinate solution in step S5 is to replace the surface non-noble metal with Pt, forming a Pt shell on the surface.
[0070] As an example, the ultrasound time in step S1 is 1 to 4 hours.
[0071] Specifically, the ultrasound time in step S1 can be any value within a range such as 1h, 2h, 3h, 4h, etc.
[0072] As an example, the transition metal precursor salt in step S2 is one or a combination of the chloride, nitrate, acetate, or acetylacetonate of the transition metal.
[0073] As an example, the carbon support in step S2 is one of XC-72, XC-72R, EC-300J, and EC-600J.
[0074] As an example, in step S2, the ratio between the total mass of the transition metal and the mass of the carbon support in the second precursor solution is 3:7 to 6:4.
[0075] Specifically, the ratio between the total mass of transition metals and the mass of carbon support in the second precursor solution can be any value within a range such as 3:7, 4:7, 5:7, 6:7, 1:1, 5:4, 6:4, etc.
[0076] As an example, the ultrasonic dispersion time in step S2 is 1 to 5 hours.
[0077] Specifically, the ultrasound time in step S1 can be any value within a range such as 1h, 2h, 3h, 4h, 5h, etc.
[0078] As an example, in step S3, the molar ratio between NaBH4 in the NaBH4 ice-water solution and the transition metal element in the second precursor solution is 5:1 to 20:1.
[0079] Specifically, the molar ratio between NaBH4 in the NaBH4 ice-water solution and the transition metal element in the second precursor solution in step S3 can be any value within a range such as 5:1, 10:1, 15:1, 20:1, etc.
[0080] As an example, the dropping rate of the NaBH4 ice-water solution in step S3 is 1 to 5 mL / min.
[0081] Specifically, the dropping rate of the NaBH4 ice-water solution in step S3 can be any value within the range of 1 mL / min, 2 mL / min, 3 mL / min, 4 mL / min, 5 mL / min, etc. As an example, the sonication time in step S3 is 15–60 min.
[0082] Specifically, the ultrasound time in step S3 can be any value within a range such as 15 min, 25 min, 35 min, 45 min, 55 min, 60 min, etc.
[0083] In addition, the time for argon gas to be introduced in step S3 is 5 to 60 minutes (e.g., 5 minutes, 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, etc.). The purpose of introducing argon gas is to remove dissolved oxygen from the solution so that the subsequent reaction can be carried out in an anaerobic environment. The more solution there is, the longer the time for introducing argon gas needs to be.
[0084] As an example, in step S4, the centrifugation speed is 8000-10000 rpm and the centrifugation time is 5-10 min.
[0085] Specifically, the centrifugation speed in step S4 can be any value within the range of 8000 rpm, 8500 rpm, 9000 rpm, 9500 rpm, 10000 rpm, etc., and the centrifugation time can be any value within the range of 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, etc.
[0086] As an example, in step S4, the washing process involves washing with anhydrous ethanol 3 to 5 times, followed by washing with deionized water.
[0087] Specifically, in step S4, the washing is performed 3, 4, or 5 times with anhydrous ethanol, followed by 1 wash with deionized water. This process can be repeated multiple times, and there are no excessive restrictions on the number of washes.
[0088] As an example, the vacuum drying temperature in step S4 is 40–80°C, and the vacuum drying time is 6–24 hours.
[0089] Specifically, the vacuum drying temperature in step S4 can be any value within the range of 40℃, 50℃, 60℃, 70℃, 80℃, etc., and the vacuum drying time can be any value within the range of 6h, 12h, 18h, 24h, etc.
[0090] As an example, in step S5, the molar ratio of Pt element in the dispersion to transition metal element in the first product dispersion is 1:1 to 1:6.
[0091] Specifically, the molar ratio of Pt element in the dispersion to transition metal element in the first product dispersion in step S5 can be any value within a range such as 1:1, 1:2, 1:4, 1:6, etc.
[0092] As an example, before mixing and stirring the Pt-based high-entropy alloy precursor dispersion under an argon atmosphere in step S5, a pretreatment step is also included, specifically, the Pt-based high-entropy alloy precursor dispersion is kept under vacuum for 15 to 30 minutes.
[0093] Specifically, the Pt-based high-entropy alloy precursor dispersion is kept under vacuum for any range of 15 min, 20 min, 25 min, 30 min, etc. The vacuum condition is to isolate oxygen and prevent oxides from forming during the displacement process.
[0094] As an example, the mixing time in step S5 is 6h to 24h.
[0095] Specifically, the mixing time in step S5 can be any value within a range such as 6h, 12h, 18h, or 24h.
[0096] In addition, the time for argon gas to be introduced in step S5 is 5 to 60 minutes (e.g., 5 minutes, 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, etc.). The purpose of introducing argon gas is to remove dissolved oxygen from the solution so that the subsequent reaction can be carried out in an anaerobic environment. The more solution there is, the longer the time for introducing argon gas needs to be.
[0097] As an example, in step S6, the centrifugation speed is 8000-10000 rpm and the centrifugation time is 5-10 min.
[0098] Specifically, the centrifugation speed can be any value within the range of 8000rpm, 8500rpm, 9000rpm, 9500rpm, 10000rpm, etc., and the centrifugation time can be any value within the range of 5min, 6min, 7min, 8min, 9min, 10min, etc.
[0099] As an example, in step S6, the washing process involves washing with anhydrous ethanol 3 to 5 times, followed by washing with deionized water.
[0100] Specifically, in step S6, the washing is performed 3, 4, or 5 times with anhydrous ethanol, followed by 1 wash with deionized water. This process can be repeated multiple times, and there are no excessive restrictions on the number of washes.
[0101] As an example, the vacuum drying temperature in step S6 is 40–80°C, and the vacuum drying time is 6–24 hours.
[0102] Specifically, the vacuum drying temperature in step S4 can be any value within the range of 40℃, 50℃, 60℃, 70℃, 80℃, etc., and the vacuum drying time can be any value within the range of 6h, 12h, 18h, 24h, etc.
[0103] As an example, the heat treatment temperature in step S7 is 300℃~500℃, and the heat treatment time is 2h~6h.
[0104] Specifically, the temperature of the heat treatment in step S7 can be any value within the range of 300℃, 350℃, 400℃, 450℃, 500℃, etc., and the heat treatment time can be any value within the range of 2h, 3h, 4h, 5h, 6h, etc.
[0105] The present invention also provides a Pt-based high-entropy intermetallic compound oxygen reduction catalyst, wherein the Pt-based high-entropy intermetallic compound oxygen reduction catalyst is prepared by the above-described preparation method of the Pt-based high-entropy intermetallic compound oxygen reduction catalyst.
[0106] Compared to catalysts with the same metal loading, the catalyst in this invention contains less Pt, with some Pt being replaced by non-precious metals. The intrinsic activity of Pt is improved by regulating the electronic structure of the non-precious metal Pt, thus achieving better catalytic performance with less Pt.
[0107] In addition, the present invention also provides an application of a Pt-based high-entropy intermetallic compound oxygen reduction catalyst, wherein the Pt-based high-entropy intermetallic compound oxygen reduction catalyst is applied in the oxygen reduction reaction catalysis process, and wherein the Pt-based high-entropy intermetallic compound oxygen reduction catalyst is prepared by the above-described preparation method of the Pt-based high-entropy intermetallic compound oxygen reduction catalyst.
[0108] To better understand the Pt-based high-entropy intermetallic compound oxygen reduction catalyst, its preparation method, and its application in this invention, specific embodiments are described below. It should be noted that these embodiments are merely descriptive and do not limit the invention in any way.
[0109] Example 1
[0110] This embodiment provides a Pt-based high-entropy intermetallic compound oxygen reduction catalyst and its preparation method. The catalyst is PtCoNiZnGa, and its preparation method includes the following steps:
[0111] S1. Add 0.125 g (0.3 mmol) potassium chloroplatinate dropwise to 50 mL of ethylene glycol and sonicate for 2 h until the solution is clear and transparent to form the first precursor solution;
[0112] S2. Dissolve 0.0208 g (0.16 mmol) of CoCl2, 0.0285 g (0.12 mmol) of NiCl2·6H2O, 0.0137 g (0.1 mmol) of ZnCl2, 0.0365 g (0.14 mmol) of Ga(NO3)3·xH2O and 0.18 g of carbon support (XC-72R) in ethylene glycol and sonicate for 2 h to obtain the second precursor solution.
[0113] S3. Mix the first precursor solution and the second precursor solution, and introduce argon gas under ultrasonication for 15 min. At the same time, add NaBH4 ice water solution (0.6 g of NaBH4 dissolved in ice water) dropwise at a dropping rate of 3 mL / min. Disperse under ultrasonication for 30 min to obtain the first product dispersion. The molar ratio of Pt element to transition metal element in the first product dispersion is 1:1.7.
[0114] S4. The first product dispersion was centrifuged at 10,000 rpm, washed three times with anhydrous ethanol, then washed once with deionized water, and then dried in a vacuum drying oven at 60°C for 12 h before grinding to obtain Pt-based high-entropy alloy precursor powder.
[0115] S5. Dissolve 0.045 g (0.1 mmol) potassium chloroplatinate in 60 mL of ethylene glycol to form a dispersion. Then add 0.1 g of Pt-based high-entropy alloy precursor powder to the dispersion and sonicate for 2 h to obtain a Pt-based high-entropy alloy precursor dispersion. Then keep the Pt-based high-entropy alloy precursor dispersion under vacuum for 30 min and then mix and stir under argon atmosphere for 12 h to obtain the second product dispersion.
[0116] S6. The second product dispersion was centrifuged at 10,000 rpm, washed three times with anhydrous ethanol, then washed once with deionized water, and then dried in a vacuum drying oven at 60°C for 12 h before grinding to obtain Pt-rich high-entropy alloy precursor powder.
[0117] S7. The Pt-rich high-entropy alloy precursor powder was heat-treated at 300°C for 4 hours in a hydrogen atmosphere to obtain a Pt-based high-entropy intermetallic compound catalyst.
[0118] See Figure 2a , 2b 2c, 2d, and 2e are the XRD, TEM, HRTEM, particle size distribution, and EDS surface distribution of the PtCoNiZnGa high-entropy intermetallic compound oxygen reduction catalyst prepared in this embodiment, respectively. As can be seen from the figures, the size of the PtCoNiZnGa high-entropy intermetallic compound nanoparticles prepared in this embodiment is about 3.4 nm, and the particle dispersion elements are uniformly distributed.
[0119] Example 2
[0120] This embodiment provides a Pt-based high-entropy intermetallic compound oxygen reduction catalyst and its preparation method. The catalyst is PtCoNiCuGa. The preparation method differs from that in Example 1 in that: in step S2, 0.0208 g (0.16 mmol) of CoCl2, 0.0285 g (0.12 mmol) of NiCl2·6H2O, 0.0137 g (0.1 mmol) of ZnCl2, and 0.0365 g (0.14 mmol) of Ga(NO3)3·xH2O are dissolved in ethylene glycol and ultrasonically dispersed for 2 h to obtain a second precursor solution; in step S7, the heat treatment temperature is 500 °C; other methods and steps are the same as in Example 1 and will not be repeated here.
[0121] See Figure 3a , 3b 3c and 3d are the XRD, TEM, HRTEM and particle size distribution diagrams of the PtCoNiCuGa high-entropy intermetallic compound oxygen reduction catalyst prepared in Example 2, respectively. As can be seen from the figure, the size of the PtCoNiCuGa high-entropy intermetallic compound nanoparticles prepared in Example 2 is about 3.9 nm, and the particles are uniformly dispersed.
[0122] Example 3
[0123] This embodiment provides a Pt-based high-entropy intermetallic compound oxygen reduction catalyst and its preparation method. The catalyst is PtCoNiCuSn, and its preparation method differs from that of Example 1 in that: in step S2, 0.0208 g (0.16 mmol) of CoCl2, 0.0285 g (0.12 mmol) of NiCl2·6H2O, 0.0137 g (0.1 mmol) of ZnCl2, and 0.019 g (0.14 mmol) of SnCl2 are dissolved in ethylene glycol and ultrasonically dispersed for 2 h to obtain a second precursor solution; in step S7, the heat treatment temperature is 400 °C; other methods and steps are the same as in Example 1 and will not be repeated here.
[0124] See Figure 4a , 4b 4c and 4d are the XRD, TEM, HRTEM and particle size distribution diagrams of the PtCoNiCuSn high-entropy intermetallic compound oxygen reduction catalyst prepared in Example 3, respectively. As can be seen from the figure, the size of the PtCoNiCuSn high-entropy intermetallic compound nanoparticles prepared in Example 3 is about 4.9 nm, and the particles are uniformly dispersed.
[0125] Comparative Example 1
[0126] This comparative example uses 40% commercial Pt / C catalyst (Johnson Matthey, model HISPEC4000).
[0127] Experimental Example 1
[0128] The Pt-based high-entropy intermetallic compound oxygen reduction catalysts prepared in Examples 1 (PtCoNiZnGa), 2 (PtCoNiCuGa), and 3 (PtCoNiCuSn) were respectively used to prepare test electrodes, and then their oxygen reduction performance was tested. The specific steps included:
[0129] A1. Prepare an ink solution by ultrasonically dispersing 2 mg of catalyst, 20 μL of 5% Nafion solution, 880 mL of ethanol and 100 mL of ultrapure water for 2 hours.
[0130] A2. Select a glassy carbon electrode tip (GC) with a diameter of 5mm and an area of 0.196cm². 2 7.6 μL of ink solution was added to the pre-polished GC, and the electrode was allowed to air dry to form the test electrode. At this point, the Pt loading was 20 μg / cm³. 2 ;
[0131] A3. The oxygen reduction performance of the test electrode was tested. Specifically, a 0.1M HClO4 solution was placed in a five-cell electrolytic cell, and N2 was introduced for half an hour to saturate the solution. Cyclic voltammetry (CV) was performed using a Shanghai Chenhua CHI760e electrochemical workstation. Then, O2 was introduced for another half hour to saturate the solution, and linear sweep voltammetry (LSV) was performed using the same workstation. During CV testing, the scan rate was 50 mV / s, with 100 scans, and the voltage range was 0.2–1.1 V / RHE. During linear sweep testing, the scan rate was 10 mV / s. 1 The scanning range is 0.2 to 1.1 V / RHE.
[0132] Experiment Example 2
[0133] A test electrode was fabricated using 40% commercial Pt / C catalyst (Johnson Matthey, model HISPEC4000), and then its oxygen reduction performance was tested. The specific steps included:
[0134] B1. Prepare an ink solution by ultrasonically dispersing 2 mg of catalyst, 20 μL of 5% Nafion solution, 880 mL of ethanol and 100 mL of ultrapure water for 2 hours.
[0135] B2. Select a glassy carbon electrode tip (GC) with a diameter of 5mm and an area of 0.196cm². 24.9 μL of ink solution was added to the pre-polished GC, and the electrode was allowed to air dry to form the test electrode. At this point, the Pt loading was 20 μg / cm³. 2 ;
[0136] B3. Test the oxygen reduction performance of the test electrode under the same conditions as in Experiment 1.
[0137] See Figure 5a and 5b As shown in the figure, the performance of the catalysts in Examples 1 to 3 is superior to that of commercial Pt / C. Among them, the half-wave potential of PtCoNiZnGa is as high as 0.913V, which is 53mV higher than the half-wave potential of commercial Pt / C of 0.86V, demonstrating excellent oxygen reduction catalytic performance.
[0138] See Figure 5c The figure compares the mass activity and specific surface area activity of the PtCoNiZnGa prepared in Example 1 with that of the commercial Pt / C catalyst in Comparative Example 1. As can be seen from the figure, the mass activity of PtCoNiZnGa is 3 times higher and the specific surface area activity is 2.5 times higher than that of commercial Pt / C, which further confirms the excellent oxygen reduction catalytic performance of PtCoNiZnGa.
[0139] Experimental Example 3
[0140] This experimental example provides a method for testing the stability of the PtCoNiZnGa high-entropy intermetallic compound oxygen reduction catalyst in Example 1, including the following steps:
[0141] The stability of the test electrode made of PtCoNiZnGa in Experimental Example 1 was tested. Specifically, a 0.1M HClO4 solution was placed in a five-cell electrolytic cell, and O2 was continuously introduced to keep the solution saturated with O2. Cyclic voltammetry (CV) was performed using a Shanghai Chenhua CHI760e electrochemical workstation. The CV test was conducted at a scan rate of 100mV / s, with 5000, 10000, and 20000 scans, and a voltage range of 0.6–1.1V / RHE. Linear sweep voltammetry (LSV) was performed using the Shanghai Chenhua CHI760e electrochemical workstation, with the same test conditions as in Experimental Example 1.
[0142] See Figure 5d , 5e The figures show the CV and LSV curves after 5000, 10000, and 20000 cycles. As can be seen from the figures, after 20000 cycles, the CV curve shows almost no change, demonstrating good stability. The half-wave potential of PtCoNiZnGa decreases by only 13mV, demonstrating excellent durability and stability.
[0143] Application Example 1
[0144] This application example provides an application of a Pt-based high-entropy intermetallic compound oxygen reduction catalyst. The Pt-based high-entropy intermetallic compound oxygen reduction catalyst (PtCoNiZnGa) prepared in Example 1 is tested in the oxygen reduction reaction catalysis process of a fuel cell. Specifically:
[0145] C1. Take the PtCoNiZnGa high-entropy intermetallic compound oxygen reduction catalyst prepared in Example 1, 20 wt% Nafion ionomer, isopropanol, and ultrapure water to form a cathode catalyst slurry. Then, use a spray gun to spray the cathode catalyst slurry onto one side of the GORE membrane to form the cathode catalyst layer. The negative Pt loading of the cathode catalyst is 0.2 mg / cm³. 2 ;
[0146] C2. Take 40wt% Pt / C, 20wt% Nafion ionomer, isopropanol, and ultrapure water to form an anode catalyst slurry. Then, use a spray gun to spray the anode catalyst slurry onto the other side of the GORE membrane to form an anode catalyst layer, wherein the Pt loading of the anode catalyst is 0.1 mg / cm³. 2 ;
[0147] C3. Fuel cell testing was conducted at 80℃, 1 MPa, and 100% humidity.
[0148] See Figure 6 The graph shows the performance of the PtCoNiZnGa high-entropy intermetallic compound oxygen reduction catalyst prepared in Example 1 in a fuel cell. As can be seen from the graph, the maximum power density reaches 1.10 W / cm². 2 It is 0.14 W / cm³ higher than commercially available Pt / C. 2 It exhibits excellent catalytic performance, making it a promising candidate for fuel cell applications.
[0149] In summary, this invention lowers the ordering transition temperature by adding low-melting-point elements to a high-entropy alloy, forming an ordered structure at 300℃. The prepared Pt-based high-entropy intermetallic compound has a particle size of only 3.4 nm. Furthermore, the prepared Pt-based high-entropy intermetallic compound oxygen reduction catalyst exhibits excellent performance in electrocatalytic oxygen reduction, with a half-wave potential as high as 0.913 V and a specific activity of 0.38 A / mg in RDE testing. Pt Its specific surface area activity reaches 0.52 mA / cm². 2 In fuel cell testing, the power density reached 1.10 W / cm³. 2 Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.
[0150] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.
Claims
1. A method for preparing a Pt-based high-entropy intermetallic compound oxygen reduction catalyst, characterized in that, The preparation method comprises the following steps: S1, dissolving potassium chloroplatinite in ethylene glycol, ultrasonic dispersion treatment, forming a first precursor solution; S2, ultrasonic dispersion of transition metal precursor salt and carbon carrier in ethylene glycol to obtain a second precursor solution; the transition metal precursor salt comprises a combination of at least four transition metal precursor salts in Co, Ni, Cu, Zn, Ga, Bi, Pb, Sn, In precursor salts; S3, mixing the first precursor solution and the second precursor solution, bubbling argon under ultrasonic, while adding NaBH4 ice water solution dropwise, ultrasonic for a period of time, to obtain a first product dispersion; the molar ratio of Pt element to transition metal element in the first product dispersion is 1:1-4:1; S4, centrifugation, washing, drying and grinding of the first product dispersion to obtain a Pt-based high-entropy alloy precursor powder; S5, weighing a certain amount of potassium chloroplatinite dissolved in ethylene glycol to form a dispersion, adding the Pt-based high-entropy alloy precursor powder to the dispersion, ultrasonic dispersion, to obtain a Pt-based high-entropy alloy precursor dispersion, then placing the Pt-based high-entropy alloy precursor dispersion in an argon atmosphere and mixing and stirring to obtain a second product dispersion; S6, centrifugation, washing, vacuum drying and grinding of the second product dispersion to obtain a surface Pt-rich high-entropy alloy precursor powder; S7, heat treatment of the surface Pt-rich high-entropy alloy precursor powder in a hydrogen atmosphere to obtain a Pt-based high-entropy intermetallic compound.
2. The method for preparing the Pt-based high-entropy intermetallic compound oxygen reduction catalyst according to claim 1, characterized in that: The ultrasonic time in step S1 is 1-4h.
3. The method for preparing the Pt-based high-entropy intermetallic compound oxygen reduction catalyst according to claim 1, characterized in that: In step S2, one or a combination of the following conditions is included: The transition metal precursor salt is one or a combination of chloride salt, nitrate salt, acetate salt or acetylacetone salt of transition metal; The carbon carrier is one of XC-72, XC-72R, EC-300J, EC-600J; The ratio between the total mass of transition metal in the second precursor solution and the mass of the carbon carrier is 3:7-6:4; The ultrasonic dispersion time is 1-5h.
4. The method for preparing the Pt-based high-entropy intermetallic compound oxygen reduction catalyst according to claim 1, characterized in that: In step S3, one or a combination of the following conditions is included: The molar ratio of NaBH4 in the NaBH4 ice water solution to the transition metal element in the second precursor solution is 5:1-20:1; The dropwise addition rate of the NaBH4 ice water solution is 1-5mL / min; The ultrasonic time is 15-60min.
5. The method for preparing the Pt-based high-entropy intermetallic compound oxygen reduction catalyst according to claim 1, characterized in that: In step S4, one or a combination of the following conditions is included: The centrifugation speed is 8000-10000rpm, and the centrifugation time is 5-10min; The washing uses anhydrous ethanol for 3-5 times, and then deionized water is used for washing; The vacuum drying temperature is 40-80℃, and the vacuum drying time is 6-24h.
6. The method for preparing the Pt-based high-entropy intermetallic compound oxygen reduction catalyst according to claim 1, characterized in that: In step S5, one or a combination of the following conditions is included: The molar ratio of Pt element in the dispersion to transition metal element in the first product dispersion is 1:1-1:6; Before mixing and stirring under argon atmosphere, the Pt-based high-entropy alloy precursor dispersion liquid further comprises a pretreatment step, specifically, the Pt-based high-entropy alloy precursor dispersion liquid is kept under vacuum condition for 15-30 min. The mixing and stirring time is 6-24 h.
7. The method for preparing the Pt-based high-entropy intermetallic compound oxygen reduction catalyst according to claim 1, characterized in that: In step S6, one or a combination of the following conditions is included: The centrifugation speed is 8000-10000 rpm, and the centrifugation time is 5-10 min. The washing is performed by using anhydrous ethanol for 3-5 times, and then using deionized water for washing; The vacuum drying temperature is 40-80℃, and the vacuum drying time is 6-24 h.
8. The method for preparing the Pt-based high-entropy intermetallic compound oxygen reduction catalyst according to claim 1, characterized in that: In step S7, the heat treatment temperature is 300-500℃, and the heat treatment time is 2-6 h.
9. A Pt-based high-entropy intermetallic compound oxygen reduction catalyst, characterized in that: The Pt-based high-entropy intermetallic compound oxygen reduction catalyst is prepared by using the preparation method of the Pt-based high-entropy intermetallic compound oxygen reduction catalyst according to any one of claims 1-8.
10. Use of a Pt-based high-entropy intermetallic compound oxygen reduction catalyst, characterized in that: The Pt-based high-entropy intermetallic compound oxygen reduction catalyst is applied to the catalytic process of oxygen reduction reaction, wherein the Pt-based high-entropy intermetallic compound oxygen reduction catalyst is prepared by using the preparation method of the Pt-based high-entropy intermetallic compound oxygen reduction catalyst according to any one of claims 1-8.