High-durability Pt fuel cell cathode catalyst and preparation method thereof
By introducing rhodium into the platinum catalyst and performing reduction etching treatment to optimize the catalyst surface alloying, the problems of low activity, poor stability and insufficient durability of existing fuel cell catalysts are solved, and a highly durable and active platinum-rhodium catalyst is achieved.
Patent Information
- Application Number
- CN202510915229.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-03
- Publication Date
- 2025-10-17
AI Technical Summary
Existing fuel cell catalysts have low activity, insufficient stability, lack of anti-reverse polarity performance, high cost, and their durability is far from what expected.
A small amount of precious metal rhodium is introduced into the platinum catalyst, and the loose metal particles are selectively etched through the reduction etching method to optimize the catalyst surface alloying process and form a platinum-rhodium catalyst.
The durability and stability of the catalyst were significantly improved, the metal loading on the catalyst surface was improved, the d-band center of Pt was lowered, the dissolution in an oxidizing environment was weakened, and the surface migration and shedding of Pt were inhibited.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to a kind of high durability Pt fuel cell cathode catalyst and its preparation method, belong to fuel cell field. BACKGROUND
[0002] Current commercial PEMFCs stack mainly relies on carbon-supported platinum (Pt / C) or platinum-cobalt (PtCo) alloy catalyst. Among them, the most widely used catalyst is still carbon-supported platinum catalyst, but this kind of catalyst has low activity, insufficient stability, lack of anti-reversal performance, high cost and other problems. Using high platinum loading platinum-based catalyst can make the catalyst layer thin, which can effectively reduce the mass transfer resistance of gas, and is of great significance to improve the output performance of fuel cell. In addition, in actual working conditions, uneven gas distribution, instantaneous start or stop and other factors can cause reverse polarization, which can seriously damage the structure of the catalyst layer and cause irreversible damage. Furthermore, the current fuel cell durability is far from the expected value of people's fuel cell durability. Therefore, developing high-performance catalysts with high platinum loading and high stability (high durability) is of great significance to the development and large-scale commercial application of fuel cells. SUMMARY
[0003] The purpose of the present application is to overcome the deficiencies in the prior art and provide a high durability Pt fuel cell cathode catalyst and its preparation method. The catalyst of the present application is prepared by introducing a small amount of noble metal rhodium into metal platinum to prepare a platinum-rhodium catalyst, which optimizes the electronic structure of metal platinum, significantly improves the durability of the catalyst, and selectively etches the metal particles that are not tightly combined with the carrier during the metal reduction and loading process on the surface of the catalyst by a special reduction etching method, and strengthens the alloying process on the surface of the catalyst, so that the durability of the catalyst is further improved.
[0004] To achieve the above technical purpose, the technical solution adopted by the embodiments of the present application is: In a first aspect, the embodiments of the present application provide a preparation method of a high durability Pt fuel cell cathode catalyst, comprising the following steps: (1) Catalyst precursor preparation: 2-10 g of carbon powder is dispersed in 2-10 L of ultrapure water, homogenized and emulsified for 5-15 min, 5.3-26.3 g of platinum source and 0.02-0.1 g of rhodium source are added, and ultrasonic treatment is performed for 10-20 min to form a uniform solution; the pH of the solution is adjusted to 9-11.5 by adding an alkaline substance, and further stirring is performed for 30-60 min. After stirring is completed, pressure filtration washing is performed and drying is performed at 60-90℃ to obtain a catalyst precursor; (2) Reduction etching treatment: 2-10 g of the catalyst precursor and 2-10 g of the ammonium salt obtained in step (1) are uniformly mixed by grinding and then placed in a tube furnace, calcined at 400-650 DEG C for 1-4 h under an inert atmosphere with a flow rate of 400-700 sccm, to obtain a high-durability Pt fuel cell cathode catalyst.
[0005] Further, in step (1), the platinum source includes one or more of potassium chloroplatinate, chloroplatinic acid, platinum nitrate, sodium chloroplatinate, and ammonium chloroplatinate, with a purity of ≥98%. The rhodium source includes one or more of rhodium phosphate, rhodium chloride, rhodium nitrate, rhodium acetate, and rhodium tribromide.
[0006] Further, in step (1), the alkaline substance is one or more of potassium hydroxide, potassium carbonate, sodium carbonate, sodium hydroxide, ammonia, and sodium bicarbonate.
[0007] Further, in step (2), the ammonium salt is one or more of ammonium iodide, ammonium chloride, and ammonium fluoride, with a purity of ≥99%.
[0008] Further, in step (2), the inert atmosphere is one or more of helium, argon, and nitrogen, with a purity of ≥99.999%.
[0009] In a second aspect, the embodiments of the present application provide a high-durability Pt fuel cell cathode catalyst prepared by the method of the first aspect.
[0010] The technical scheme provided by the embodiments of the present application has the following beneficial effects: 1. The preparation method of the present application introduces a small amount of the noble metal rhodium. The introduction of rhodium reduces the d-band center of platinum, weakens the adsorption energy of Pt and oxygen-containing intermediates (such as OH* and O*), reduces the dissolution of Pt in an oxidizing environment, and, through strong interaction with Pt, inhibits the surface migration and shedding of Pt atoms, while the corrosion resistance of Rh itself also delays the overall corrosion of the surface metal of the catalyst.
[0011] 2. The preparation method of the present application can selectively etch the surface metal of the catalyst while strengthening the alloying of the surface metal of the catalyst, thereby removing unstable metal particles on the surface, improving the loading of the surface metal of the catalyst while strengthening the alloying of the surface metal of the catalyst, and significantly improving the durability of the catalyst in a novel form and with simple steps. BRIEF DESCRIPTION OF DRAWINGS
[0012] Figure 1 is the XRD comparison chart of the catalyst prepared in Example 1 and Comparative Examples 1-2 of the present application.
[0013] Figure 2a ,Figure 2b The transmission electron microscope surface metal dispersion of the catalyst prepared in Example 1 and Comparative Example 2, respectively, is compared.
[0014] Figure 3 The half-cell linear voltammetry of Example 2, Comparative Example 1 and Comparative Example 2 of the present application is shown.
[0015] Figure 4a Figure 4b Figure 4c The half-cell durability before and after of the catalyst prepared in Example 3, Comparative Example 2 and Comparative Example 1 of the present application, respectively, is shown.
[0016] Figure 5 The fuel cell single cell test polarization curve of the catalyst prepared in Example 4, Comparative Example 1 and Comparative Example 2 of the present application, respectively, is compared.
[0017] Figure 6a Figure 6b Figure 6c The fuel cell single cell accelerated durability test before and after polarization curve of the catalyst prepared in Example 5, Comparative Example 2 and Comparative Example 1 of the present application, respectively, is compared. DETAILED DESCRIPTION
[0018] In order to make the objectives, technical solutions and advantages of the present application more clear, the present application is further described in detail below with reference to the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.
[0019] Example 1 A preparation method of a high durability Pt fuel cell cathode catalyst, comprising the following steps: (1) Catalyst precursor preparation: 2 g of XC-72R carbon powder is dispersed in 2 L of ultrapure water, homogenously emulsified for 5 min, 5.3 g of platinum nitrate (Guo Yao, analytical purity 99.8%) and 0.02 g of rhodium chloride (Guo Yao, analytical purity 99.8%) are added, and ultrasonic treatment is performed for 10 min to form a uniform solution; after adjusting the pH of the solution to 9 by adding ammonia water (Guo Yao, 25-28 wt%), further stirring is performed for 30 min, after completion of stirring, pressure filtration washing is performed and drying is performed at 60°C to obtain a catalyst precursor; (2) Reduction etching treatment: 2 g of the catalyst precursor obtained in step (1) and 2 g of ammonium iodide (Guo Yao, analytical purity 99.8%) are ground and mixed uniformly, then placed in a tube furnace, calcined at 400°C for 1 h under a nitrogen gas (purity 99.999%) atmosphere with a flow rate of 400 sccm, and a high durability Pt fuel cell cathode catalyst is obtained; (3) Fuel cell single cell test: 200 mg of the above-prepared platinum rhodium catalyst was accurately weighed; 20 mL of pure water, 15 mL of isopropyl alcohol and 1.5 mL of 5 wt% perfluorosulfonic acid resin solution (DuPont D520) were measured and added to the catalyst, and the cell was crushed for 30 min to form a uniform catalyst ink, which was uniformly coated on a cut proton exchange membrane, which was recorded as a cathode; the platinum carbon catalyst was weighed in the same way and coated on the other side of the above-mentioned proton exchange membrane, which was recorded as an anode, to form a CCM; the gas diffusion layer used was SGL 28BC type GDL. The baltic FuelCells QCF25 rapid assembly test fixture was disassembled, and the thickness limiting sheet, the first piece of GDL, the CCM and the second piece of GDL were sequentially placed in the fixture, and after being fixed, the pneumatic button was rotated to complete the clamping. After the gas pipeline was connected, the air tightness test was qualified, and the single cell test was carried out.
[0020] Single cell test conditions: single cell area 25 cm 2 , the stoichiometric ratio of anode to cathode is 1.5:2.5, the anode dew point is set to 64℃, the cathode dew point is 64℃, the anode inlet stack pressure is 1.1 bar, the cathode inlet stack pressure is 1.0 bar, and the cell test temperature is 80℃.
[0021] Example 2 A method for preparing a high-durability Pt fuel cell cathode catalyst, comprising the following steps: (1) Catalyst precursor preparation: 10 g of XC-72R carbon powder was dispersed in 10 L of ultrapure water, homogenized for 15 min, and then 26.3 g of chloroplatinic acid (National Pharmaceutical, analytical purity 99.8%) and 0.1 g of rhodium acetate (National Pharmaceutical, analytical purity 99.8%) were added. Ultrasonic for 20 min to form a uniform solution; add sodium hydroxide (National Pharmaceutical, analytical purity 99.8%) to adjust the pH of the solution to 11.5, and further stir for 60 min. After stirring, filter washing and drying at 90℃, a catalyst precursor is obtained; (2) Reduction etching treatment: 10 g of catalyst precursor obtained in step (1) and 10 g of ammonium chloride (National Pharmaceutical, analytical purity 99.8%) were ground and mixed uniformly, then placed in a tube furnace and calcined at 650℃ for 4h under an argon gas (purity 99.999%) atmosphere with a flow rate of 700sccm to obtain a high-durability Pt fuel cell cathode catalyst.
[0022] (3) The fuel cell single cell test of the high-durability Pt fuel cell cathode catalyst prepared in this embodiment is the same as that of Example 1.
[0023] Example 3 The difference between this example and Example 1 is that the basic substance added in step (1) is potassium hydroxide, and the pH of the solution is adjusted to 9.5. The other steps are the same as those in Example 1. The fuel cell single cell test of the high-durability Pt fuel cell cathode catalyst prepared by using this example is the same as that in Example 1.
[0024] Example 4 The difference between this example and Example 2 is that the inert atmosphere power in step (2) is 450 sccm, and the calcination temperature is 500°C. The other steps are the same as those in Example 2. The fuel cell single cell test of the high-durability Pt fuel cell cathode catalyst prepared by using this example is the same as that in Example 1.
[0025] Example 5 The difference between this example and Example 1 is that the pH of the solution is adjusted to 10.5 in step (1), and the calcination temperature is 600°C. The other steps are the same as those in Example 1. The fuel cell single cell test of the high-durability Pt fuel cell cathode catalyst prepared by using this example is the same as that in Example 1.
[0026] Comparative Example 1 This comparative example provides a platinum-carbon catalyst. The difference between this comparative example and Example 1 is that only platinum nitrate is added in step (1) without adding rhodium chloride, and no ammonium salt is added in step (2). The other proportions and conditions are the same as those in Example 1.
[0027] Comparative Example 2 This comparative example provides a platinum-rhodium-carbon catalyst without reduction etching. The difference between this comparative example and Example 1 is that no ammonium salt is added in step (2). The other proportions and conditions are the same as those in Example 1.
[0028] From Figure 1 It can be seen that the standard four platinum peaks appear between 40° and 90° in Example 1, Comparative Example 1 and Comparative Example 2, and the intensities are basically the same. Compared with Comparative Example 1, the platinum peaks of Example 1 and Comparative Example 2 all appear different degrees of right shift, and the shift of Example 1 is the largest. The right shift indicates that the platinum lattice is compressed, and the alloying degree is higher. The shift of Example 1 and Comparative Example 2 is caused by the addition of rhodium, and the larger shift of Example 1 than Comparative Example 2 is caused by the further reduction by the high-temperature decomposition of ammonium iodide into ammonia gas in the reduction etching process. The better the lattice compression effect and the alloying degree, the better the activity and durability of the catalyst.
[0029] Figure 2b is the surface metal distribution of the catalyst prepared in Comparative Example 2. It can be seen from the figure that there are obvious large metal agglomerates on the surface, which tend to have weak binding force with the carrier and are easily corroded during the fuel cell reaction, thus leading to poor catalyst durability. Figure 2a is the surface metal distribution of the catalyst prepared in Example 1. It can be seen from the figure that there are no large metal agglomerates on the surface, and the surface metal is uniformly dispersed, indicating that the reduction etching treatment can etch away the large metal agglomerates with weak binding force with the carrier, thus improving the durability of the surface metal of the catalyst.
[0030] From Figure 3 the linear voltammogram, the mass activity of Example 2 is calculated to be 0.2020 A / mgPt, the mass activity of Comparative Example 2 is 0.2002 A / mgPt, and the mass activity of Comparative Example 1 is 0.0968 A / mgPt. The activity of Example 2 is slightly higher than that of Comparative Example 2, and the mass activities of Example 2 and Comparative Example 2 are both much greater than that of Comparative Example 1, indicating that the addition of Rh can improve the activity of the catalyst to a certain extent.
[0031] From Figure 4a the linear voltammogram, the mass activity of Example 2 is calculated to be 0.2020 A / mgPt, the mass activity of Comparative Example 2 is 0.2002 A / mgPt, and the mass activity of Comparative Example 1 is 0.0968 A / mgPt. The activity of Example 2 is slightly higher than that of Comparative Example 2, and the mass activities of Example 2 and Comparative Example 2 are both much greater than that of Comparative Example 1, indicating that the addition of Rh can improve the activity of the catalyst to a certain extent. Figure 4b It can be seen from the linear voltammogram that the mass activities of the catalyst prepared in Comparative Example 2 before and after durability are 0.2002 A / mgPt and 0.1826 A / mgPt, respectively, and the attenuation rate is 8.79%. Figure 4c It can be seen from the linear voltammogram that the mass activities of the catalyst prepared in Comparative Example 1 before and after durability are 0.0968 A / mgPt and 0.0499 A / mgPt, respectively, and the attenuation rate is 48.45%. Compared with the three, the catalyst prepared in Example 3 with the addition of Rh and reduction etching treatment has better durability than that prepared in Comparative Example 2 without reduction etching treatment, and is much better than that prepared in Comparative Example 1 without the addition of Rh and reduction etching treatment, indicating that the addition of Rh and reduction etching treatment can significantly improve the durability of the catalyst.
[0032] From Figure 5 the linear voltammogram, the mass activity of Example 2 is calculated to be 0.2020 A / mgPt, the mass activity of Comparative Example 2 is 0.2002 A / mgPt, and the mass activity of Comparative Example 1 is 0.0968 A / mgPt. The activity of Example 2 is slightly higher than that of Comparative Example 2, and the mass activities of Example 2 and Comparative Example 2 are both much greater than that of Comparative Example 1, indicating that the addition of Rh can improve the activity of the catalyst to a certain extent. 2 @0.668V, the performance of Comparative Example 2 is 2A / cm 2 @0.653V, and the performance of Comparative Example 1 is 2A / cm 2@0.611V. Compared with the other two, the fuel cell single cell performance of Example 4 is the best, which is due to the addition of rhodium and the reduction etching treatment, so that the surface noble metal platinum is more evenly dispersed, and the lattice compression effect occurs, which optimizes the adsorption of active sites to reaction intermediates, thereby greatly improving the performance of the catalyst cell.
[0033] From Figure 6a The fuel cell single cell accelerated durability test curve of Example 5 can be obtained, and the performance of Example 5 before and after the accelerated durability test is almost unchanged; from Figure 6b It can be seen that the performance of Comparative Example 2 before and after durability is 2A / cm 2 @0.653V and 2A / cm 2 @0.621V, the potential decayed by 32mV; from Figure 6c It can be seen that the performance of Comparative Example 1 before and after durability is 2A / cm 2 @0.611V and 2A / cm 2 @0.567V, the potential decayed by 44mV. Compared with the other two, the durability of Example 5 is the best, which shows that the addition of rhodium and the reduction etching treatment have a greater improvement on the durability of the fuel cell under actual working conditions.
[0034] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application is described in detail with reference to the examples, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the present application, and they should be covered in the scope of the claims of the present application.
Claims
1. A method for preparing a high-durability Pt fuel cell cathode catalyst, characterized in that: The following steps are involved: (1) Preparation of catalyst precursor: 2-10 g of carbon powder was dispersed in 2-10 L of ultrapure water, homogenized and emulsified for 5-15 min, 5.3-26.3 g of platinum source and 0.02-0.1 g of rhodium source were added, and ultrasonication was performed for 10-20 min to form a uniform solution; alkaline substances were added to adjust the pH of the solution to 9-11.5, and the solution was further stirred for 30-60 min. After stirring, the solution was filtered and washed, and dried at 60-90 ° C to obtain a catalyst precursor; (2) Reduction etching treatment: 2-10 g of the catalyst precursor obtained in step (1) and 2-10 g of ammonium salt were ground and mixed evenly, and then placed in a tubular furnace, and calcined at 400-650 ° C for 1-4 h in an inert atmosphere with a flow rate of 400-700 sccm to obtain a high-durability Pt fuel cell cathode catalyst.
2. The method for preparing a high-durability Pt fuel cell cathode catalyst according to claim 1, wherein: In step (1), the platinum source includes one or more of potassium chloroplatinate, chloroplatinic acid, platinum nitrate, sodium chloroplatinate and ammonium chloroplatinate, with a purity of ≥98%; The rhodium source includes one or more of rhodium phosphate, rhodium chloride, rhodium nitrate, rhodium acetate and rhodium tribromide.
3. The method for preparing a high-durability Pt fuel cell cathode catalyst according to claim 1, wherein: In step (1), the alkaline substance is one or more of potassium hydroxide, potassium carbonate, sodium carbonate, sodium hydroxide, ammonia water and sodium bicarbonate.
4. The method for preparing a high-durability Pt fuel cell cathode catalyst according to claim 1, wherein: In step (2), the ammonium salt is one or more of ammonium iodide, ammonium chloride and ammonium fluoride, and the purity is ≥99%.
5. The method for preparing a high-durability Pt fuel cell cathode catalyst according to claim 1, wherein: In step (2), the inert atmosphere is one or more of helium, argon and nitrogen, with a purity of ≥99.999%.
6. A high-durability Pt fuel cell cathode catalyst, characterized in that The method is prepared according to any one of claims 1 to 5.