Preparation method of Ta-doped Ru-based oxide and application of Ta-doped Ru-based oxide as proton exchange membrane water electrolysis anode catalyst

Abstract

The invention discloses a preparation method of a Ta-doped Ru-based oxide and application of the Ta-doped Ru-based oxide as a proton exchange membrane water electrolysis anode catalyst, and belongs to the field of catalysts and preparation thereof. The problems that an existing proton exchange membrane water electrolysis anode catalyst is high in cost, low in catalytic activity and insufficient in stability are solved. The preparation method comprises the following steps: dispersing pyrrole in isopropanol to obtain a solution A; dissolving metal ruthenium salt and tantalum salt in deionized water to obtain a solution B; dissolving ammonium persulfate in deionized water to obtain a solution C; uniformly mixing the solution A and the solution B, then adding the solution C to obtain a black gel substance, and carrying out ice bath standing, room temperature standing and freeze drying to obtain black powder 1; performing heat treatment on the black powder 1 in an air atmosphere to obtain black powder 2; dispersing the black powder 2 into deionized water, performing ultrasonic dispersion, suction filtration and drying to obtain the Ta-doped RuO2 catalyst. The preparation method is simple, and the prepared Ru-based catalyst shows excellent performance in a proton exchange membrane water electrolysis hydrogen production electrolytic tank.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts and their preparation, and particularly relates to a method for preparing Ta-doped Ru-based oxide and its application as an anode catalyst for proton exchange membrane water electrolysis. Background Art

[0002] The production of green hydrogen from green electricity derived from renewable energy is an important technical support for promoting decarbonization. Among them, proton exchange membrane water electrolysis (PEMWE) hydrogen production technology has many advantages such as strong coupling with fluctuating renewable energy, high current density, and high purity of hydrogen production. It is the key to achieving zero-carbon emission green hydrogen production. However, its oxygen evolution reaction on the anode side has a high overpotential and slow reaction kinetics, and requires the use of a large amount of precious metal Ir, which seriously limits the large-scale commercialization of PEMWE hydrogen production technology. Therefore, the development of a highly active, highly stable, and low-cost oxygen evolution reaction electrocatalyst that can replace Ir is crucial to improving the energy conversion efficiency of PEMWE technology and reducing the cost of hydrogen production.

[0003] Ru-based materials have higher intrinsic activity than Ir-based catalysts, with an abundance in the earth's crust about 40 times that of Ir, and a price less than one-tenth of Ir, making them the best choice to replace Ir. However, Ru-based catalysts have poor stability under acidic oxygen evolution reaction conditions. This is mainly due to the high reactivity of lattice oxygen in Ru-based oxides during the oxygen evolution process, which makes it easy for lattice oxygen to oxidize, leading to structural damage. Therefore, only by developing effective strategies to reduce the reactivity of lattice oxygen in Ru-based oxides and inhibit lattice oxygen oxidation can Ru-based materials be used as anode catalysts for proton exchange membrane water electrolysis to achieve the goals of improving energy efficiency and reducing costs. Summary of the Invention

[0004] The purpose of the present invention is to solve the technical problem of poor stability of Ru-based anode catalysts in proton exchange membrane water electrolysis for hydrogen production in the prior art, and to provide a method for preparing Ta-doped Ru-based oxide (RuO2) and its application as an anode catalyst for proton exchange membrane water electrolysis for hydrogen production.

[0005] The technical solutions adopted by the present invention to solve the above technical problems are as follows.

[0006] The preparation method of Ta-doped Ru-based oxide (RuO2) comprises the following steps: Step 1: Disperse pyrrole in isopropanol and ultrasonically disperse it in an ice bath for 0.5-2 h to obtain solution A; dissolve metal ruthenium salt and tantalum salt in deionized water and ultrasonically disperse it in an ice bath for 0.5-2 h to obtain solution B; and simultaneously dissolve ammonium persulfate in deionized water and ultrasonically disperse it in an ice bath for 0.5-2 h to obtain solution C; Step 2: Evenly mix the obtained solution A and the obtained solution B under stirring, and stir for 0.5-5 minutes to obtain solution D; Step 3: Add solution C to the obtained solution D under stirring and stir for 0.5-3 min to obtain a black gel-like substance; Step 4: Place the obtained black gel-like substance in an ice bath for 0.5-2 h, then at room temperature for 10-18 h, freeze in liquid nitrogen for 10-30 min, and freeze-dry in a freeze dryer at -50°C to -60°C for 36-48 h to obtain a black powder 1; Step 5: Take black powder 1, heat treat it at 300-800°C in air atmosphere for 3-6 hours, and cool it to room temperature to obtain black powder 2; Step 6: Disperse the obtained black powder 2 in deionized water, perform ultrasonic dispersion, stir for 6-10 h, filter three times with ethanol and / or water, and then vacuum dry in a drying oven at 50-70 ºC to obtain a Ta-doped RuO2 catalyst.

[0007] Preferably, in step 1, the volume ratio of pyrrole to isopropanol is 1:5 to 1:20, and the dispersion method is ultrasonic dispersion in an ice bath.

[0008] Preferably, in step 1, the metal ruthenium salt is one of ruthenium trichloride, ruthenium acetate, ruthenium acetylacetonate or potassium chlororuthenate, the metal tantalum salt is sodium tantalate or potassium fluorotantalate, the molar ratio of the tantalum salt to the ruthenium salt is 1:5 to 1:50, the mass volume ratio of the ruthenium salt to deionized water is 1 mg:0.05mL to 1 mg:0.2mL, and the dispersion method is ultrasonic dispersion in an ice bath.

[0009] Preferably, in step 1, the mass volume ratio of ammonium persulfate to deionized water is 1 g: 2 mL to 1 g: 10 mL, and the dispersion method is ultrasonic dispersion in an ice bath.

[0010] Preferably, in step 2, the volume ratio of solution A to solution B is 1:2 to 2:1; the stirring temperature is room temperature, and the stirring time is 0.5-5 min.

[0011] Preferably, in step three, the volume ratio of solution D to solution C is 1:1 to 3:1; the stirring temperature is room temperature, and the stirring time is 0.5-3 min.

[0012] Preferably, in step 5, the heating rate is 2-10 ºC min -1 , the cooling method is natural cooling.

[0013] The present invention also provides the use of Ta-doped RuO2 prepared by the above method as an anode catalyst for proton exchange membrane water electrolysis. The Ta-doped RuO2 catalyst has low preparation cost, high catalytic activity and good stability.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses stable fluorotantalate or tantalate as a Ta precursor, avoiding the hydrolysis of tantalum salts. In an aqueous solvent with low environmental requirements, pyrrole molecules are used to in-situ polymerize and anchor uniformly dispersed Ru and Ta ions. Phase separation between the two is avoided during heat treatment, and the element distribution is uniform. Compared with commercial ruthenium oxide, the Ta-O bond energy in the prepared Ta-doped RuO2 (839 kJ mol -1 ) is significantly higher than the Ru-O bond energy (528 kJ mol -1 ), the activity of lattice oxygen participating in the reaction is significantly reduced; using it as an anode catalyst for proton exchange membrane water electrolysis has the advantages of low cost, high catalytic activity and good stability.

[0015] The preparation method of Ta-doped RuO2 of the present invention is simple, environmentally friendly, suitable for industrial large-scale production, and provides a feasible path for the large-scale preparation of low-cost, high-activity, and long-life proton exchange membrane water electrolysis hydrogen production anode catalysts, which has great application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a scanning electron microscope (SEM) image of Ta-doped RuO2 prepared in Example 1 of the present invention; Figure 2 This is a transmission electron microscope (TEM) image of Ta-doped RuO2 prepared in Example 1 of the present invention; Figure 3 This is the EDS element mapping image of Ta-doped RuO2 prepared in Example 1 of the present invention; Figure 4 The X-ray diffraction (XRD) spectrum of Ta-doped RuO2 prepared in Example 1 of the present invention; Figure 5 This is the linear sweep voltammetry curve of Ta-doped RuO2 prepared in Example 1 of the present invention in 0.5 mol / L sulfuric acid solution; Figure 6 The Ta-doped RuO2 prepared in Example 1 of the present invention was subjected to a 10 mA cm -2 Chronopotentiometry curves under current density; Figure 7 The proton exchange membrane water electrolysis hydrogen production electrolytic cell assembled with Ta-doped RuO2 prepared in Example 1 of the present invention as the anode catalyst was used at 500 mA cm -2Chronopotentiometry curves at different current densities. DETAILED DESCRIPTION

[0017] In order to further understand the present invention, the preferred embodiments of the present invention are described below in conjunction with specific implementation methods, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention rather than limiting the patent requirements of the present invention.

[0018] The raw materials used in the following examples were all analytically pure, commercially available conventional chemicals and did not require further treatment. Example 1

[0019] Disperse 0.5 mL of pyrrole in 5 mL of isopropanol and disperse ultrasonically on ice for 1 h to obtain solution A. Dissolve 0.3 mmol of ruthenium trichloride and 0.03 mmol of potassium fluorotantalate in 6 mL of deionized water and disperse ultrasonically on ice for 1 h to obtain solution B. Dissolve 1.5 g of ammonium persulfate in 5 mL of deionized water and disperse ultrasonically on ice for 1 h to obtain solution C.

[0020] Solution A was poured into solution B under stirring and stirred at room temperature for 3 minutes to obtain solution D. Solution C was then added to solution D and stirred at room temperature for 1 minute to obtain a black gel-like substance. The obtained black gel-like substance was placed in an ice bath for 0.5 hours, allowed to stand at room temperature for 12 hours, frozen in liquid nitrogen for 15 minutes, and freeze-dried in a freeze dryer at -50°C for 40 hours to obtain black powder 1. The black powder 1 was taken and heated at 5°C for 1 minute. -1 The heating rate was increased from room temperature to 450°C, and heat treatment was carried out at 450°C in an air atmosphere for 4 hours. The powder was then cooled to room temperature to obtain black powder 2. Black powder 2 was dispersed in deionized water and stirred for 6 hours. The mixture was then filtered three times with a mixture of ethanol and water, and then dried in a vacuum oven at 60°C for 6 hours to obtain the Ta-doped RuO2 catalyst.

[0021] The Ta-doped RuO2 catalyst of Example 1 was characterized by electron microscopy. Figure 1-3 As shown, the obtained Ta-doped RuO2 is composed of nanoparticles, and the EDS element mapping results show that Ta, Ru, and O elements are evenly distributed in the sample.

[0022] The Ta-doped RuO2 catalyst of Example 1 was subjected to X-ray diffraction analysis, and the results were as follows: Figure 4 As shown, the diffraction peak corresponds to the rutile phase RuO2, and there is no corresponding TaO x The peak of Ta does not lead to the formation of new phase.

[0023] The Ta-doped RuO2 catalyst of Example 1 was subjected to linear sweep voltammetry in a 0.5 mol / L sulfuric acid solution. The results are as follows: Figure 5 As shown, the obtained catalyst exhibits better activity than the commercial RuO2 catalyst.

[0024] The Ta-doped RuO2 catalyst of Example 1 was subjected to a 0.5 mol / L sulfuric acid solution at 10 mA cm -2 The chronopotentiometry test was performed at the current density, and the results were as follows: Figure 6 As shown, the obtained catalyst exhibits better stability than the commercial RuO2 catalyst, indicating that the lattice oxygen oxidation process may be suppressed.

[0025] The Ta-doped RuO2 of Example 1 was used as the anode catalyst to assemble a proton exchange membrane water electrolysis hydrogen production electrolytic cell. -2 The chronopotentiometry curve at the current density is as follows Figure 7 As shown, it exhibits high stability and corrosion resistance. Example 2

[0026] Disperse 1 mL of pyrrole in 5 mL of isopropanol and ultrasonically disperse in an ice bath for 2 hours to obtain solution A; dissolve 0.3 mmol of ruthenium trichloride and 0.06 mmol of potassium fluorotantalate in 12 mL of deionized water and ultrasonically disperse in an ice bath for 2 hours to obtain solution B; dissolve 3 g of ammonium persulfate in 6 mL of deionized water and ultrasonically disperse in an ice bath for 2 hours to obtain solution C. Pour solution A into solution B under stirring and stir at room temperature for 5 minutes to obtain solution D; then add solution C to solution D and stir at room temperature for 2 minutes to obtain a black gel-like substance. The resulting black gel-like substance was placed in an ice bath and allowed to stand for 2 hours, then allowed to stand at room temperature for 18 hours, frozen in liquid nitrogen for 30 minutes, and freeze-dried in a freeze dryer at -50°C for 48 hours to obtain black powder 1. Take black powder 1 and precipitate it at 10°C for 1 minute -1 The heating rate was increased from room temperature to 650°C. Heat treatment was performed at 650°C in air for 4 hours, followed by cooling to room temperature to obtain black powder 2. Black powder 2 was dispersed in deionized water and stirred for 10 hours. The powder was then filtered three times with a mixture of ethanol and water and dried under vacuum at 70°C for 6 hours to obtain the Ta-doped RuO2 catalyst.

[0027] The Ta-doped RuO2 of Example 2 was characterized by electron microscopy, analyzed by X-ray diffraction spectrum, and subjected to electrochemical performance testing, and the results were similar to those of Example 1. Example 3

[0028] Disperse 0.5 mL of pyrrole in 10 mL of isopropanol and ultrasonically disperse in an ice bath for 0.5 h to obtain solution A. Dissolve 0.5 mmol of ruthenium trichloride and 0.01 mmol of potassium fluorotantalate in 5.5 mL of deionized water and ultrasonically disperse in an ice bath for 0.5 h to obtain solution B. Dissolve 1.5 g of ammonium persulfate in 15 mL of deionized water and ultrasonically disperse in an ice bath for 0.5 h to obtain solution C. Pour solution A into solution B under stirring and stir at room temperature for 5 min to obtain solution D. Then, add solution C to solution D and stir at room temperature for 3 min to obtain a black gel-like substance. The resulting black gel-like substance was placed in an ice bath and allowed to stand for 1 h, then at room temperature for 18 h, frozen in liquid nitrogen for 20 min, and freeze-dried in a freeze dryer at -50°C for 48 h to obtain black powder 1. Take black powder 1 and precipitate it at 2°C for 1 min. -1 The heating rate was increased from room temperature to 450°C, and heat treatment was carried out at 450°C in an air atmosphere for 6 hours. The powder was then cooled to room temperature to obtain black powder 2. Black powder 2 was dispersed in deionized water and stirred for 8 hours. The powder was then filtered three times with a mixture of ethanol and water, and dried under vacuum at 50°C for 6 hours to obtain the Ta-doped RuO2 catalyst.

[0029] The Ta-doped RuO2 of Example 3 was characterized by electron microscopy, analyzed by X-ray diffraction spectrum, and subjected to electrochemical performance testing, and the results were similar to those of Example 1. Example 4

[0030] Disperse 0.5 mL of pyrrole in 5 mL of isopropanol and ultrasonically disperse on ice for 1 h to obtain solution A. Dissolve 0.3 mmol of ruthenium acetate and 0.03 mmol of sodium tantalate in 6 mL of deionized water and ultrasonically disperse on ice for 1 h to obtain solution B. Dissolve 1.5 g of ammonium persulfate in 5 mL of deionized water and ultrasonically disperse on ice for 1 h to obtain solution C. Pour solution A into solution B while stirring and stir at room temperature for 3 min to obtain solution D. Then, add solution C to solution D and stir at room temperature for 1 min to obtain a black gel-like substance. The resulting black gel-like substance was placed in an ice bath for 0.5 h, then at room temperature for 12 h, frozen in liquid nitrogen for 15 min, and freeze-dried in a freeze dryer at -50°C for 40 h to obtain black powder 1. Take black powder 1 and precipitate it at 5°C for 1 min. -1 The heating rate was increased from room temperature to 450°C, and heat treatment was carried out at 450°C in an air atmosphere for 4 hours. The powder was then cooled to room temperature to obtain black powder 2. Black powder 2 was dispersed in deionized water and stirred for 6 hours. The mixture was then filtered three times with a mixture of ethanol and water, and then dried in a vacuum oven at 60°C for 6 hours to obtain the Ta-doped RuO2 catalyst.

[0031] The Ta-doped RuO2 of Example 4 was characterized by electron microscopy, analyzed by X-ray diffraction spectrum, and subjected to electrochemical performance testing, and the results were similar to those of Example 1. Example 5

[0032] Disperse 0.5 mL of pyrrole in 5 mL of isopropanol and ultrasonically disperse on ice for 1 h to obtain solution A. Dissolve 0.3 mmol of ruthenium trichloride and 0.03 mmol of potassium fluorotantalate in 6 mL of deionized water and ultrasonically disperse on ice for 1 h to obtain solution B. Dissolve 1.5 g of ammonium persulfate in 5 mL of deionized water and ultrasonically disperse on ice for 1 h to obtain solution C. Pour solution A into solution B while stirring and stir at room temperature for 3 min to obtain solution D. Then, add solution C to solution D and stir at room temperature for 1 min to obtain a black gel-like substance. The resulting black gel-like substance was placed in an ice bath for 0.5 h, then at room temperature for 12 h, frozen in liquid nitrogen for 15 min, and freeze-dried in a freeze dryer at -50°C for 40 h to obtain black powder 1. Take black powder 1 and precipitate it at 3°C for 1 min. -1 The heating rate was increased from room temperature to 400°C, and heat treated at 400°C in air for 6 hours. The mixture was then cooled to room temperature to obtain black powder 2. Black powder 2 was dispersed in deionized water and stirred for 6 hours. The mixture was then filtered three times with a mixture of ethanol and water, and dried under vacuum at 60°C for 6 hours to obtain the Ta-doped RuO2 catalyst.

[0033] The Ta-doped RuO2 of Example 5 was characterized by electron microscopy, analyzed by X-ray diffraction spectrum, and subjected to electrochemical performance testing, and the results were similar to those of Example 1. Example 6

[0034] Disperse 0.5 mL of pyrrole in 5 mL of isopropanol and ultrasonically disperse on ice for 1 h to obtain solution A. Dissolve 0.3 mmol of potassium chlororuthenate and 0.03 mmol of potassium fluorotantalate in 6 mL of deionized water and ultrasonically disperse on ice for 1 h to obtain solution B. Dissolve 1.5 g of ammonium persulfate in 5 mL of deionized water and ultrasonically disperse on ice for 1 h to obtain solution C. Pour solution A into solution B while stirring and stir at room temperature for 3 min to obtain solution D. Then, add solution C to solution D and stir at room temperature for 1 min to obtain a black gel-like substance. The resulting black gel-like substance was placed in an ice bath for 0.5 h, then at room temperature for 12 h, frozen in liquid nitrogen for 15 min, and freeze-dried in a freeze dryer at -50°C for 40 h to obtain black powder 1. Take black powder 1 and precipitate it at 5°C for 1 min. -1The heating rate was increased from room temperature to 450°C, and heat treatment was carried out at 450°C in an air atmosphere for 4 hours. The powder was then cooled to room temperature to obtain black powder 2. Black powder 2 was dispersed in deionized water and stirred for 6 hours. The mixture was then filtered three times with a mixture of ethanol and water, and then dried in a vacuum oven at 60°C for 6 hours to obtain the Ta-doped RuO2 catalyst.

[0035] The Ta-doped RuO2 of Example 6 was characterized by electron microscopy, analyzed by X-ray diffraction spectrum, and subjected to electrochemical performance testing, and the results were similar to those of Example 1.

[0036] Obviously, the above embodiments are merely examples for the purpose of clarity of description, and other variations or modifications may be made based on the above description. Therefore, obvious variations or modifications derived therefrom still fall within the scope of protection of the present invention.

Claims

1. A method for preparing Ta-doped Ru-based oxide, characterized in that: Here are the steps: Step 1: Disperse pyrrole in isopropanol and ultrasonically disperse it in an ice bath for 0.5-2 h to obtain solution A; dissolve metal ruthenium salt and tantalum salt in deionized water and ultrasonically disperse it in an ice bath for 0.5-2 h to obtain solution B; and simultaneously dissolve ammonium persulfate in deionized water and ultrasonically disperse it in an ice bath for 0.5-2 h to obtain solution C; Step 2: Evenly mix the obtained solution A and the obtained solution B under stirring, and stir for 0.5-5 minutes to obtain solution D; Step 3: Add solution C to the obtained solution D under stirring and stir for 0.5-3 min to obtain a black gel-like substance; Step 4: Place the obtained black gel-like substance in an ice bath for 0.5-2 h, then at room temperature for 10-18 h, freeze in liquid nitrogen for 10-30 min, and freeze-dry in a freeze dryer at -50°C to -60°C for 36-48 h to obtain a black powder 1; Step 5: Take black powder 1, heat treat it at 300-800°C in air atmosphere for 3-6 hours, and cool it to room temperature to obtain black powder 2; Step 6: Disperse the obtained black powder 2 in deionized water, perform ultrasonic dispersion, stir for 6-10 hours, filter with ethanol and / or water, and then dry in a drying oven at 50-70°C to obtain a Ta-doped Ru-based oxide catalyst.

2. The method for preparing Ta-doped Ru-based oxide according to claim 1, characterized in that: In step 1, the volume ratio of pyrrole to isopropanol is 1:5 to 1:20; the molar ratio of the tantalum salt to the ruthenium salt is 1:5 to 1:50, the mass volume ratio of the ruthenium salt to deionized water is 1 mg:0.05 mL to 1 mg:0.2 mL; and the mass volume ratio of ammonium persulfate to deionized water is 1 g:2 mL to 1 g:10 mL.

3. The method for preparing Ta-doped Ru-based oxide according to claim 1, wherein: In the step 1, the metal ruthenium salt is ruthenium trichloride, ruthenium acetate, ruthenium acetylacetonate or potassium chlororuthenate; and the metal tantalum salt is sodium tantalate or potassium fluorotantalate.

4. The method for preparing Ta-doped Ru-based oxide according to claim 1, characterized in that: In the step 2, the volume ratio of solution A to solution B is 1:2 to 2:1; the stirring temperature is room temperature, and the stirring time is 0.5-5 min.

5. The method for preparing Ta-doped Ru-based oxide according to claim 1, characterized in that: In step 3, the volume ratio of solution D to solution C is 1:1 to 3:1; the stirring temperature is room temperature, and the stirring time is 0.5-3 min.

6. The method for preparing Ta-doped Ru-based oxide according to claim 1, characterized in that: In step 5, the heating rate is 2-10 ºC min -1 , the cooling method is natural cooling.

7. The method for preparing Ta-doped Ru-based oxide according to claim 1, characterized in that: In the step six, the filtration and washing times are three times, and the drying condition is vacuum drying.

8. The method for preparing Ta-doped Ru-based oxide according to claim 1, characterized in that: The Ta-doped Ru-based oxide catalyst is a phase-separation-free product, has low preparation cost, high catalytic activity and good stability.

9. Use of the Ta-doped Ru-based oxide prepared by the method according to any one of claims 1 to 8 as an anode catalyst for proton exchange membrane water electrolysis.

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