An iridium oxide catalyst based on adams molten salt method of sacrifice template and its preparation method and application
The preparation of iridium oxide catalysts by the Adams molten salt method using sacrificial templates solves the problem of particle agglomeration and separation of iridium oxide catalysts under high-temperature calcination, and realizes the efficient application of iridium oxide particles with high crystallinity and high specific surface area in PEM water electrolysis.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JAPHL POWERTRAIN SYST
- Filing Date
- 2026-03-23
- Publication Date
- 2026-06-05
AI Technical Summary
Existing iridium oxide catalysts suffer from a conflict in calcination temperature during preparation, making it difficult to simultaneously control particle size to achieve both high crystallinity and high specific surface area. Furthermore, the separation process is complex, making it difficult to meet the large-scale commercial demand for PEM water electrolysis.
The Adams molten salt method based on sacrificial templates is adopted. By introducing sacrificial template raw materials that can be thermally decomposed at low temperatures, the crystallinity of iridium oxide is improved and particle agglomeration is inhibited under high temperature calcination conditions. At the same time, the separation process is simplified, and the particle size is controlled by utilizing the steric hindrance and surface anchoring effect of the sacrificial template.
The stability and catalytic activity of iridium oxide particles under high-temperature calcination were improved, maintaining a particle size of less than 10 nm, simplifying the separation process. The catalyst exhibited excellent stability and high specific surface area in PEM water electrolysis, with a low overpotential performance of ≤1.68 V.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst technology for hydrogen production through water electrolysis, specifically relating to an iridium oxide catalyst based on the Adams molten salt method using sacrificial templates, its preparation method, and its application. Background Technology
[0002] Hydrogen energy, as a clean alternative energy source, is a key direction for solving the global energy crisis and environmental problems. Hydrogen production by water electrolysis is the core technology path for hydrogen energy production. The OER reaction of PEM water electrolysis anode requires a highly efficient catalyst to reduce the overpotential. IrO2, due to its excellent acid stability and OER catalytic activity, has become the preferred catalyst for PEM water electrolysis anode.
[0003] However, there are two major problems in the preparation of existing iridium oxide catalysts. First, there is a contradiction in calcination temperature. Low calcination temperature below 380℃ is required to control particle size, so that the primary particle size is <10 nm. However, the low temperature leads to poor crystallinity of iridium oxide, which is easily dissolved and lost in the acidic environment of PEM, shortening the life of the electrolyzer. If the calcination temperature is increased to improve crystallinity, it will cause iridium oxide particles to agglomerate, and the catalytic activity will decrease significantly. Second, the separation process is complicated. Iridium oxide particles of 10 nm or less are easily suspended during the washing process and are difficult to precipitate and separate. Multiple centrifugation or dialysis is required, which greatly increases the complexity and cost of the process.
[0004] While the traditional Adams molten salt process using sodium nitrate or potassium nitrate as a medium simplifies synthesis, it cannot simultaneously optimize the three mutually restrictive factors of particle size, crystallinity, and separation difficulty. Low-temperature calcination can control particle size to within 10 nm, maintaining high specific surface area and high OER activity, but the crystallinity is low, mostly low-crystallinity or amorphous IrO. x Under the acidic high potential of PEM, Ir dissolves and is lost severely, and the catalyst is rapidly deactivated. Raising the temperature to above 390℃ can improve crystallinity, form a more stable rutile phase, and improve durability, but it also leads to particle agglomeration and growth, a significant decrease in specific surface area, and a marked reduction in activity, making it difficult to meet the large-scale commercial demand of PEM water electrolysis. Summary of the Invention
[0005] The purpose of this invention is to provide an iridium oxide catalyst based on the Adams molten salt method using a sacrificial template and its preparation method. By introducing a sacrificial template raw material that can be thermally decomposed at low temperatures, the crystallinity of iridium oxide is improved under high-temperature calcination conditions, while effectively inhibiting particle agglomeration and greatly simplifying the subsequent separation process.
[0006] Another objective of this invention is to provide an application of an iridium oxide catalyst as an anode catalyst in the oxygen evolution reaction of water electrolysis.
[0007] This invention provides a method for preparing an iridium oxide catalyst based on the Adams molten salt method using a sacrificial template, the method comprising the following steps:
[0008] 1) A metal salt mixture is obtained by ball milling and mixing molten salt medium, sacrificial template material, and iridium material;
[0009] 2) The metal salt mixture is calcined, and then the calcined product is washed with water and acid. The acid-washed product is then cleaned and dried to obtain the iridium oxide catalyst.
[0010] In step 1), the ball milling speed is 200~400 rpm and the ball milling time is 40~90 min.
[0011] In step 1), the molten salt medium is one or more of sodium nitrate or potassium nitrate.
[0012] In step 1), the sacrificial template material is one or more of the following: zinc, aluminum, magnesium, or calcium nitrates, nitrites, carbonates, acetates, or oxalates.
[0013] In step 1), the iridium raw material is one or more of iridium chloride or chloroiridium acid.
[0014] In step 1), the mass ratio of the molten salt medium, the sacrificial template material, and the iridium material is 5~10:0.8~2:1.
[0015] In step 2), the calcination temperature is 390~420℃, the calcination time is 15~60min, and the gas atmosphere is air.
[0016] In step 2), the acid used for pickling is one or more of hydrochloric acid, nitric acid, or sulfuric acid.
[0017] This invention provides an iridium oxide catalyst prepared using the above-described preparation method.
[0018] This invention provides an application of the iridium oxide catalyst described above as an anode catalyst in the oxygen evolution reaction of water electrolysis.
[0019] A membrane electrode is prepared using an iridium oxide catalyst based on the Adams molten salt method with a sacrificial template as described in this invention as the active material.
[0020] During the heating process, the sacrificial template material first undergoes thermal decomposition in the molten salt medium at 390℃, releasing gases such as NO2, O2 and CO2, and is transformed in situ into nano-sized oxide particles. These nano-oxide particles serve as sacrificial templates and have a large specific surface area and good dispersibility.
[0021] In a molten salt environment, iridium raw materials are oxidized by nitrates, undergoing the following typical reaction:
[0022] 2IrCl3 + 6NaNO3 → 2Ir(NO3)3 + 6NaCl;
[0023] 2Ir(NO3)3 → 2IrO2 + 6NO2 + O2;
[0024] The generated iridium oxide nanoparticles with extremely small primary particle size are uniformly loaded in situ and anchored to the surface of the nanoscale sacrificial template under the influence of molten salt flow and thermal drive.
[0025] By reaching temperatures above 390°C and further calcining in air, the crystallinity of iridium oxide is increased, transforming it from a low-crystallinity or quasi-amorphous state to a highly crystalline rutile phase IrO2. At the same time, the steric hindrance and surface anchoring effect provided by the sacrificial template effectively inhibit the aggregation and growth of iridium oxide particles.
[0026] After calcination, the residual sodium nitrate or potassium nitrate molten salts are first washed with water to remove them, and then the sacrificial template is removed by acid washing with a dilute acid solution to obtain the iridium oxide catalyst.
[0027] Compared with the prior art, the present invention has the following advantages:
[0028] 1. By sacrificing the steric hindrance of the template, the primary particle size of the catalyst is kept within the range of less than 10 nm, which successfully inhibits high-temperature particle agglomeration and ensures high specific surface area and high catalytic activity;
[0029] 2. The composite particles formed by the sacrificial template material are easy to settle and filter, and the water washing process is efficient, avoiding the difficulty in separation caused by the suspension of traditional fine iridium oxide particles;
[0030] 3. The catalyst exhibits excellent performance, with the iridium oxide catalyst performing well at 60 °C and 1 A / cm². 2 Voltage ≤ 1.68 V at current density. Attached Figure Description
[0031] Figure 1 This is a TEM image of the iridium oxide catalyst prepared in Example 1;
[0032] Figure 2 This is a mapping image of the iridium oxide catalyst prepared in Example 1;
[0033] Figure 3 This is a TEM image of the iridium oxide catalyst prepared in Comparative Example 1. Detailed Implementation
[0034] 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 in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0035] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.
[0036] Example 1
[0037] A method for preparing an iridium oxide catalyst based on the Adams molten salt process using a sacrificial template, the method comprising the following steps:
[0038] 1) Take 10.0 g sodium nitrate, 2.0 g zinc nitrate and 1.4 g iridium chloride, add 5.0 mL ethanol, and use a zirconia ball mill jar at a speed of 300 rpm for 60 minutes to form a metal salt mixture;
[0039] 2) The metal salt mixture was calcined at 420 °C in air and held for 40 minutes. The product was washed four times with deionized water, and then 200 mL of 0.5 mol / L hydrochloric acid was added and stirred at room temperature for 180 minutes. The acid-washed product was washed again and centrifuged. This process was repeated four times. After vacuum drying at 80 °C for 24 hours, the iridium oxide catalyst was obtained.
[0040] Example 2
[0041] A method for preparing an iridium oxide catalyst based on the Adams molten salt process using a sacrificial template, the method comprising the following steps:
[0042] 1) Take 15.0 g sodium nitrate, 5.0 g aluminum nitrate and 2.8 g chloroiridic acid, add 8.0 mL of a 1:1 mixture of ethanol and water, and ball mill in an agate ball mill jar at 400 rpm for 40 minutes to form a metal salt mixture;
[0043] 2) The metal salt mixture was heated to 390 °C in air and kept at that temperature for 30 minutes. The product was washed three times with deionized water. Then, 200 mL of 0.5 mol / L sulfuric acid was added and the mixture was stirred and acid-washed at room temperature for 180 minutes. The acid-washed product was washed again and centrifuged. This process was repeated four times. The product was then vacuum-dried at 80 °C for 24 h to obtain the iridium oxide catalyst.
[0044] Example 3
[0045] A method for preparing an iridium oxide catalyst based on the Adams molten salt process using a sacrificial template, the method comprising the following steps:
[0046] 1) Take 80 g of sodium nitrate, 15 g of magnesium nitrate and 10 g of iridium chloride, add 3 mL of ethylene glycol solvent, and use a zirconia ball mill jar at a speed of 200 rpm for 90 minutes to form a metal salt mixture;
[0047] 2) The metal salt mixture was calcined at 410 °C in air and held for 35 minutes. The product was washed 5 times with deionized water, and then 300 mL of 0.5 mol / L sulfuric acid was added and the mixture was stirred and acid-washed at 50 °C for 90 minutes. The acid-washed product was washed again and centrifuged. This process was repeated 4 times. After drying at 100 °C for 24 hours, the iridium oxide catalyst was obtained.
[0048] Example 4
[0049] A method for preparing an iridium oxide catalyst based on the Adams molten salt process using a sacrificial template, the method comprising the following steps:
[0050] 1) Take 100g sodium nitrate, 8g zinc nitrate, 8g calcium nitrite and 20g iridium chloride, add 20mL ethylene glycol solvent, and use a zirconia ball mill jar at a speed of 350 rpm for 60 minutes to form a metal salt mixture;
[0051] 2) The metal salt mixture was calcined at 400 °C in air and held for 30 minutes. The product was washed 5 times with deionized water, and then 300 mL of 0.2 mol / L nitric acid was added and stirred at 50 °C for 60 minutes. The acid-washed product was washed again and centrifuged. After repeating this process 4 times, the product was dried at 80 °C for 24 hours to obtain the iridium oxide catalyst.
[0052] Comparative Example 1
[0053] A method for preparing an iridium oxide catalyst, the method comprising the following steps:
[0054] The difference between this comparative example and Example 3 is that magnesium nitrate was not added in step 1), while the rest is the same as in Example 3.
[0055] Application Example 1
[0056] A method for preparing a membrane electrode, the method being as follows:
[0057] 1) Weigh 12 g of the catalyst prepared in each example and comparative example, mix it with a resin solution containing 3 g Nafion, 22.5 g ethylene glycol and 37.5 g pure water, sonicate and stir for 2 hours to make a slurry;
[0058] 2) Apply the slurry evenly to a membrane area of 20 cm². 2 On the proton exchange membrane, the catalyst loading was controlled at 0.6 mg / cm³. 2 After coating, the membrane electrode is dried at 80 °C for 24 hours to obtain the membrane electrode.
[0059] Test Example 1
[0060] Performance testing:
[0061] The PEM water electrolysis single-cell test system was used for evaluation. The test temperature was controlled at 60 ℃ and the pressure was atmospheric pressure. The initial performance was tested by constant current step polarization curve testing, and the test current density range was 0.01–1.0 A / cm. 2 Record 1.0 A / cm 2 The slot voltage, denoted as V 初始 The durability test was conducted in constant current mode at 1.0 A / cm². 2 The system was continuously run for 3000 hours, and voltage changes were monitored. The test results were marked as V. 测试后 .
[0062] The test results of each embodiment and comparative example are shown in Table 1 below:
[0063] Table 1 Performance Test Table
[0064]
[0065] Comparative Example 1, because it did not use magnesium nitrate as a template, maintained a value of 1.0 A / cm. 2 The voltage at this point is significantly higher than in the other examples because the lack of sacrificial template binding leads to excessively large iridium dioxide particles, indicating that the sacrificial template can effectively constrain the aggregation of iridium dioxide particles; the TEM characterization of Example 1 and Comparative Example 1 is as follows: Figure 1 and Figure 3 As shown, Figure 1 The iridium oxide particles did not agglomerate and had a particle size of less than 10 nm. Figure 3 The iridium oxide particles showed obvious agglomeration.
[0066] It should be noted that the above embodiments are merely some preferred embodiments of the present invention, and not all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.
[0067] The above description of the embodiments is intended to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.
Claims
1. A method for preparing an iridium oxide catalyst based on the Adams molten salt process using sacrificial templates, characterized in that, The preparation method includes the following steps: 1) A metal salt mixture is obtained by ball milling and mixing molten salt medium, sacrificial template material, and iridium material; 2) The metal salt mixture is calcined, and then the calcined product is washed with water and acid. The acid-washed product is then cleaned and dried to obtain the iridium oxide catalyst.
2. The method for preparing iridium oxide catalyst based on the Adams molten salt method using sacrificial templates according to claim 1, characterized in that, In step 1), the molten salt medium is one or more of sodium nitrate or potassium nitrate.
3. The method for preparing iridium oxide catalyst based on the Adams molten salt method using sacrificial templates according to claim 1, characterized in that, In step 1), the sacrificial template material is one or more of the following: zinc, aluminum, magnesium, or calcium nitrates, nitrites, carbonates, acetates, or oxalates.
4. The method for preparing iridium oxide catalyst based on the Adams molten salt method using sacrificial templates according to claim 1, characterized in that, In step 1), the iridium raw material is one or more of iridium chloride or chloroiridium acid.
5. The method for preparing the iridium oxide catalyst based on the Adams molten salt process using sacrificial templates according to any one of claims 1-4, characterized in that, In step 1), the mass ratio of the molten salt medium, the sacrificial template material, and the iridium material is 5~10:0.8~2:
1.
6. The method for preparing iridium oxide catalyst based on the Adams molten salt method using sacrificial templates according to claim 1, characterized in that, In step 2), the calcination temperature is 390~420℃, the calcination time is 15~60min, and the gas atmosphere is air.
7. The method for preparing iridium oxide catalyst based on the Adams molten salt method using sacrificial templates according to claim 1, characterized in that, In step 2), the acid used for pickling is one or more of hydrochloric acid, nitric acid, or sulfuric acid.
8. An iridium oxide catalyst prepared by the preparation method according to claim 1.
9. The application of the iridium oxide catalyst as described in claim 8 as an anode catalyst in the oxygen evolution reaction of water electrolysis.
10. A membrane electrode, wherein the membrane electrode is prepared using the iridium oxide catalyst of claim 8 as the active material.