Preparation method of rutile ruthenium dioxide catalyst introducing cation vacancies

Abstract

The present invention discloses a preparation method of a rutile ruthenium dioxide catalyst introducing cation vacancies. First, glucose and urea are dissolved in ultrapure water to obtain a transparent mixed solution; then, ruthenium trichloride hydrate and a magnesium compound are added to the transparent mixed solution for hydrothermal reaction, and then the obtained porous foam-like precursor is annealed to obtain a precursor catalyst of ruthenium dioxide nanoparticles doped with magnesium metal; finally, under acidic electrolyte conditions, the precursor catalyst of ruthenium dioxide nanoparticles is subjected to CV cycle activation to obtain a rutile ruthenium dioxide catalyst introducing cation vacancies. The present invention adopts continuous hydrothermal reaction and annealing treatment, which is beneficial to the formation of an ordered lattice structure, improves and optimizes the catalytic performance of the product, and uses an acidic electrolyte to in-situ dissolve metallic magnesium, thereby generating a rutile ruthenium dioxide catalyst introducing cation vacancies, and the activity and stability of the catalyst are significantly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of oxygen evolution reaction catalysts, and specifically to a preparation method of rutile ruthenium dioxide catalyst introducing cation vacancies. Background Art

[0002] Hydrogen energy plays a core role in renewable energy and the decarbonization of the global energy system due to its advantages such as green cleanliness, high energy density, high safety, and wide application scenarios. However, in the hydrogen production process by electrolyzing water, the oxygen evolution reaction (OER) occurring at the anode seriously affects the efficiency of the hydrogen evolution reaction at the cathode due to its slow four-electron kinetic process and high energy barrier, restricting the development of the energy conversion and storage fields. Therefore, designing and preparing high-activity oxygen evolution reaction functional catalyst materials is the key to promoting their practical applications. Currently, in the field of electrochemical catalytic material design and synthesis, research on defect regulation mainly focuses on anion defect regulation (such as oxygen vacancies, sulfur vacancies, phosphorus vacancies, etc.), while there is little work on regulating the microstructure through cation defects. Compared with anion defect regulation, the formation energy of cation defects is higher, the formation process is more complex and energy-consuming, and the challenge of defect concentration is also challenging. It should be noted that cation vacancies have the advantages of high conductivity, regulating the adsorption process of intermediates, and regulating the local environmental reaction environment, which is beneficial to the synergistic improvement of the activity and stability of the oxygen evolution reaction. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a preparation method of rutile ruthenium dioxide catalyst introducing cation vacancies. First, a magnesium-doped ruthenium dioxide nanoparticle precursor catalyst with an ordered lattice structure and small particle size is prepared by hydrothermal method and annealing treatment, and then the metal magnesium in the precursor catalyst is electrochemically dissolved in situ to generate a rutile ruthenium dioxide catalyst introducing cation vacancies, and the activity and stability of this catalyst are significantly improved.

[0004] The technical solution of the present invention is as follows:

[0005] A preparation method of rutile ruthenium dioxide catalyst introducing cation vacancies specifically includes the following steps:

[0006] (1) Dissolve glucose and urea in ultrapure water and perform ultrasonic treatment to obtain a homogeneous transparent mixed solution;

[0007] (2) Add ruthenium trichloride hydrate and magnesium compound to the homogeneous transparent mixed solution and stir well to dissolve to obtain a brownish-black mixed solution;

[0008] (3) Hydrothermally react the brownish-black mixed solution at 120-150 °C for 8-10 hours to obtain a porous foam-like precursor;

[0009] (4) Anneal the porous foam-like precursor to obtain a precursor catalyst of ruthenium dioxide nanoparticles doped with magnesium metal;

[0010] (5) Under acidic electrolyte conditions, perform CV cyclic activation on the precursor catalyst of ruthenium dioxide nanoparticles to obtain a rutile ruthenium dioxide catalyst with introduced cation vacancies.

[0011] The mass ratio of the glucose to the urea is 5:0.5 - 1.5.

[0012] The magnesium compound is selected from magnesium nitrate or magnesium chloride.

[0013] The mass ratio of the ruthenium trichloride hydrate to the magnesium compound is 3 - 5:1.

[0014] The atmosphere for annealing the porous foam-like precursor is air, the annealing heating rate is 5 - 10 °C / min, the annealing temperature is 500 - 600 °C, and the annealing holding time is 10 - 14 hours.

[0015] The specific steps for performing CV cyclic activation on the precursor catalyst of ruthenium dioxide nanoparticles under acidic electrolyte conditions are as follows: After adding the precursor catalyst of ruthenium dioxide nanoparticles doped with magnesium metal to a solvent and performing ultrasonic homogenization treatment, add a small amount of perfluorosulfonic acid solution thereto, and then perform ultrasonic homogenization treatment again to obtain a uniform slurry. Then, drop the uniform slurry onto a glassy carbon electrode, and after natural drying, use it as a working electrode, use a platinum mesh electrode as a counter electrode, and use a silver chloride electrode as a reference electrode to perform CV cyclic activation under acidic electrolyte conditions. After the CV cyclic activation is completed, wash and dry the slurry on the glassy carbon electrode to obtain a rutile ruthenium dioxide catalyst with introduced cation vacancies.

[0016] The solvent is a mixed solution of water and ethanol, and the volume ratio of water to ethanol is 3:1.

[0017] The acidic electrolyte is selected as a sulfuric acid solution with a concentration of 0.1 - 1 mol / L.

[0018] The scan rate of the CV cyclic activation is 5 mV / s, the applied voltage range is 1.2 - 1.4 V vs. RHE, and the number of times of CV cyclic activation is 20 - 50 times.

[0019] Advantages of the present invention:

[0020] (1) In the present invention, magnesium metal atoms are introduced into the precursor catalyst, significantly reducing the size of ruthenium dioxide nanoparticles (about 10 nm), thereby increasing the specific surface area and the exposed area of active sites. Moreover, under acidic electrolyte conditions, the in-situ dissolution of magnesium metal atoms can be achieved to generate a ruthenium dioxide catalyst with cation vacancies introduced.

[0021] (2) Through continuous hydrothermal and annealing treatments in the present invention, the magnesium metal-doped ruthenium dioxide nanoparticles form an ordered lattice structure, improving and optimizing the catalytic performance of the product.

[0022] (3) The prepared ruthenium dioxide catalyst with cation vacancies introduced in the present invention can significantly reduce the overpotential of the oxygen evolution reaction, significantly enhance the activity of the oxygen evolution reaction, and has excellent oxygen evolution reaction stability.

[0023] (4) The raw materials of the present invention have low cost and are easy to obtain. The preparation method has a simple process, a short preparation time, and is easy to be experimentally and industrially promoted. Description of the Drawings

[0024] Figure 1 is a scanning electron microscope (SEM) image of the magnesium metal-doped ruthenium dioxide nanoparticle precursor catalyst prepared in Example 1 of the present invention.

[0025] Figure 2 is a high-resolution transmission electron microscope (HRTEM) image of the magnesium metal-doped ruthenium dioxide nanoparticle precursor catalyst prepared in Example 1 of the present invention.

[0026] Figure 3 is a high-angle annular dark-field scanning electron microscope (HADDF-STEM) image of the ruthenium dioxide catalyst with cation vacancies introduced prepared in Example 1 of the present invention.

[0027] Figure 4 is a transmission electron microscope (TEM) image of the rutile ruthenium dioxide catalyst prepared in Comparative Example 1 of the present invention.

[0028] Figure 5 is a linear sweep voltammetry (LSV) curve graph of the ruthenium dioxide catalyst with cation vacancies introduced prepared in Example 1 of the present invention, the rutile ruthenium dioxide catalyst prepared in Comparative Example 1, and commercial ruthenium dioxide.

[0029] Figure 6 is a constant current life stability test graph of the ruthenium dioxide catalyst with cation vacancies introduced prepared in Example 1 of the present invention, the rutile ruthenium dioxide catalyst prepared in Comparative Example 1, and commercial ruthenium dioxide. Detailed Embodiments

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Example 1

[0031] A preparation method of a rutile ruthenium dioxide catalyst introducing cation vacancies specifically includes the following steps:

[0032] (1) Dissolve 10 g of glucose and 2 g of urea in 10 mL of ultrapure water and ultrasonically treat for 30 minutes to obtain a homogeneous transparent mixed solution;

[0033] (2) Add 105.6 mg of ruthenium trichloride hydrate and 28.53 mg of magnesium nitrate to the homogeneous transparent mixed solution and stir well for 30 minutes to dissolve, obtaining a brownish-black mixed solution;

[0034] (3) Hydrothermally react the brownish-black mixed solution at 140 °C for 8 hours to obtain a porous foam-like precursor;

[0035] (4) Transfer the porous foam-like precursor to a reaction boat, and then place the reaction boat in a muffle furnace for annealing treatment. The annealing atmosphere is air, the annealing heating rate is 5 °C / min, the annealing temperature is 500 °C, and the annealing holding time is 12 hours to obtain a black magnesium metal-doped ruthenium dioxide nanoparticle precursor catalyst;

[0036] (5) Under acidic electrolyte conditions, perform CV cyclic activation on the ruthenium dioxide nanoparticle precursor catalyst. Specifically, add 5 mg of the magnesium metal-doped ruthenium dioxide nanoparticle precursor catalyst to 1 mL of a solvent (a mixed solution of water and ethanol with a volume ratio of 3:1) and perform ultrasonic homogenization treatment, then add 30 μL of perfluorosulfonic acid solution (to increase the viscosity of the slurry), and then perform ultrasonic homogenization treatment again to obtain a uniform slurry. Then use a micropipette to transfer 5 μL of the uniform slurry and drop it onto a glassy carbon electrode with a diameter of 3 mm, and let it dry naturally to be used as a working electrode. Use a platinum mesh electrode as the counter electrode and a silver chloride electrode as the reference electrode, and perform CV cyclic activation under the condition of a 0.5 mol / L H2SO4 electrolyte solution. The scan rate of CV cyclic activation is 5 mV / s, the applied voltage range is 1.2~1.4 V vs. RHE, and the number of CV cyclic activation is 20~50 times. After the CV cyclic activation is completed, clean and dry the slurry on the glassy carbon electrode to obtain a rutile ruthenium dioxide catalyst introducing cation vacancies, marked as MgRuO2.

[0037] Figure 1 SEM (100 nm) image of the ruthenium dioxide nanoparticle precursor catalyst doped with magnesium metal prepared in step (4). It can be seen from Figure 1 that the nanoparticle size of the ruthenium dioxide nanoparticle precursor catalyst doped with magnesium metal is about 10 nm. Introducing magnesium metal atoms significantly reduces the size of ruthenium dioxide nanoparticles.

[0038] Figure 2 HRTEM image of the ruthenium dioxide nanoparticle precursor catalyst doped with magnesium metal prepared in step (4). It can be seen from Figure 2 that the exposed active surfaces of the ruthenium dioxide nanoparticle precursor catalyst doped with magnesium metal are (110) and (101) active surfaces.

[0039] Figure 3 HADDF-STEM image of the rutile ruthenium dioxide catalyst with introduced cation vacancies prepared in step (5). It can be seen from Figure 3 that obvious atomic vacancies exist in the regular atomic sequence because the introduced magnesium atoms are in-situ dissolved under acidic electrolyte conditions and thus detached from the lattice to form cation vacancies. Comparative Example 1

[0040] A preparation method of a rutile-type ruthenium dioxide catalyst. Step (1) is the same as step (1) of Example 1. Step (2) is to directly add 105.6 mg of ruthenium trichloride hydrate into a homogeneous transparent mixed solution and stir well for 30 minutes to dissolve, obtaining a mixed solution. Steps (3) and (4) are the same as steps (3) and (4) of Example 1. The product of step (4) is a rutile-type ruthenium dioxide catalyst, labeled as p-RuO2.

[0041] Figure 4 TEM (100 nm) image of the rutile-type ruthenium dioxide catalyst prepared in step (4) of Comparative Example 1. By comparing Figure 1 and Figure 4 it can be seen that introducing magnesium nitrate significantly reduces the nanoparticle size of the catalyst product.

[0042] Performance analysis:

[0043] I. The OER performance tests were carried out on the products of Example 1 (MgRuO2), the products of Comparative Example 1 (p-RuO2), and commercial ruthenium dioxide (com-RuO2). The tests were all carried out on a Shanghai Chenhua CHI 760E electrochemical workstation, which was equipped with a typical three-electrode system. The OER performance tests of the three catalysts were carried out in a 0.5 mol / L H2SO4 electrolyte solution. After adding 5 mg of each of the three catalysts to 1 mL of solvent (a mixed solution of water and ethanol with a volume ratio of 3:1) and performing ultrasonic homogenization treatment, 30 μL of perfluorosulfonic acid solution was added thereto, and then ultrasonic homogenization treatment was carried out again to obtain a uniform slurry. Then, 5 μL of the uniform slurry was pipetted with a micropipette and dropped onto a glassy carbon electrode with a diameter of 3 mm. After natural drying, it was used as the working electrode, a platinum mesh electrode was used as the counter electrode, and a silver chloride electrode was used as the reference electrode. The OER performance test was carried out under the condition of a 0.5 mol / L H2SO4 electrolyte solution. The scan rate of the OER performance test was 10 mV / s, and the applied voltage range was 1.2 - 1.7 V vs. RHE. The LSV curve diagram of the OER performance test is shown in Figure 5 , Figure 5 The abscissa of which is the test voltage, and the ordinate is the current density (unit: mA / cm 2 ).

[0044] From Figure 5 it can be seen that at a current density of 10 mA / cm 2 , the overpotential of com-RuO2 was 340 mV (the overpotential was obtained by subtracting the standard electrode potential of water decomposition, 1.23 V, from the test voltage), the overpotential of p-RuO2 was 296 mV, and the overpotential of MgRuO2 was as low as 216 mV. Thus, it shows that the rutile ruthenium dioxide catalyst introducing cation vacancies prepared in Example 1 of the present invention can significantly reduce the overpotential of the oxygen evolution reaction and significantly improve the activity of the oxygen evolution reaction.

[0045] II. The constant current stability tests were carried out on the products of Example 1 (MgRuO2), the products of Comparative Example 1 (p-RuO2), and commercial ruthenium dioxide (com-RuO2). The tests were all carried out on a Shanghai Chenhua CHI 760E electrochemical workstation. The stability tests of the three catalysts were carried out in a 0.5 mol / L H2SO4 electrolyte solution. After adding 5 mg of each of the three catalysts to 1 mL of solvent (a mixed solution of water and ethanol with a volume ratio of 3:1) and performing ultrasonic homogenization treatment, 30 μL of perfluorosulfonic acid solution was added thereto, and then ultrasonic homogenization treatment was carried out again to obtain a uniform slurry. Then, 14.2 μL of the uniform slurry was pipetted with a micropipette and dropped onto an area of 0.2 cm 2On the carbon paper, after natural drying, it is used as the working electrode, a platinum mesh electrode is used as the counter electrode, and a silver chloride electrode is used as the reference electrode. A constant current stability test is carried out under the condition of a 0.5 mol / L H2SO4 electrolyte solution, that is, at the set constant current density, observe the relationship between voltage and time. The constant current (10 mA / cm 2 ) life stability test results are shown in Figure 6 , Figure 6 The abscissa of which is time (unit: hour h), and the ordinate is the test voltage.

[0046] From Figure 6 it can be seen that at a current density of 10 mA / cm 2 , the stable operation time of com-RuO2 is 10 hours, the stable operation time of p-RuO2 is 20 hours, and MgRuO2 can stably operate for 400 hours without obvious performance decay. This shows that the rutile ruthenium dioxide catalyst with cation vacancies prepared in Example 1 of the present invention exhibits excellent oxygen evolution reaction stability.

[0047] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation method of rutile ruthenium dioxide catalyst introducing cation vacancies, characterized in that: Specifically, it includes the following steps: (1) Dissolve glucose and urea in ultrapure water and perform ultrasonic treatment to obtain a homogeneous transparent mixed solution; (2) Add ruthenium(III) chloride hydrate and magnesium compound to the homogeneous transparent mixed solution, and stir well to dissolve to obtain a brownish-black mixed solution; the mass ratio of ruthenium(III) chloride hydrate to magnesium compound is 5:1; (3) Hydrothermally react the brownish-black mixed solution at 120 - 150 °C for 8 - 10 hours to obtain a porous foam-like precursor; (4) Anneal the porous foam-like precursor to obtain a magnesium metal-doped ruthenium dioxide nanoparticle precursor catalyst; (5) Under acidic electrolyte conditions, perform CV cyclic activation on the ruthenium dioxide nanoparticle precursor catalyst. The specific steps are as follows: Add the magnesium metal-doped ruthenium dioxide nanoparticle precursor catalyst powder to a solvent and perform ultrasonic homogenization treatment, then add a small amount of perfluorosulfonic acid solution thereto, and then perform ultrasonic homogenization treatment again to obtain a uniform slurry. Then, drop the uniform slurry onto a glassy carbon electrode, and after natural drying, use it as a working electrode, use a platinum mesh electrode as a counter electrode, and a silver chloride electrode as a reference electrode to perform CV cyclic activation under acidic electrolyte conditions. After the CV cyclic activation is completed, wash and dry the slurry on the glassy carbon electrode to obtain a rutile ruthenium dioxide catalyst with introduced cation vacancies.

2. The preparation method of a rutile ruthenium dioxide catalyst introducing cation vacancies according to claim 1, characterized in that: The mass ratio of the glucose to the urea is 5:0.5 - 1.

5.

3. The preparation method of a rutile ruthenium dioxide catalyst introducing cation vacancies according to claim 1, characterized in that: The magnesium compound is selected from magnesium nitrate or magnesium chloride.

4. The preparation method of a rutile ruthenium dioxide catalyst introducing cation vacancies according to claim 1, characterized in that: The atmosphere for annealing the porous foam-like precursor is air, the annealing heating rate is 5 - 10 °C / min, the annealing temperature is 500 - 600 °C, and the annealing holding time is 10 - 14 hours.

5. The preparation method of a rutile ruthenium dioxide catalyst introducing cation vacancies according to claim 1, characterized in that: The solvent is a mixed solution of water and ethanol, and the volume ratio of water to ethanol is 3:

1.

6. The preparation method of a rutile ruthenium dioxide catalyst introducing cation vacancies according to claim 1, characterized in that: The acidic electrolyte is selected from sulfuric acid solution with a concentration of 0.1 - 1 mol / L.

7. The preparation method of a rutile ruthenium dioxide catalyst introducing cation vacancies according to claim 1, characterized in that: The scan rate of the CV cyclic activation is 5 mV / s, the applied voltage range is 1.2 - 1.4 V vs. RHE, and the number of CV cyclic activation is 20 - 50 times.

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