Preparation method of rutile ruthenium dioxide catalyst with introduced cation vacancy

Abstract

The invention discloses a preparation method of a rutile ruthenium dioxide catalyst with introduced cation vacancies. The preparation method comprises the following steps: firstly, dissolving glucose and urea in ultrapure water to obtain a transparent mixed solution; then adding ruthenium trichloride hydrate and a magnesium compound into the transparent mixed solution to carry out hydrothermal reaction, and then carrying out annealing treatment on the obtained porous foamed precursor to obtain a magnesium metal doped ruthenium dioxide nanoparticle precursor catalyst; and finally, under the condition of acidic electrolyte, carrying out CV circulation activation on the ruthenium dioxide nanoparticle precursor catalyst to obtain the rutile ruthenium dioxide catalyst with introduced cation vacancy. According to the method, continuous hydrothermal reaction and annealing treatment are adopted, formation of an ordered lattice structure is facilitated, the catalytic performance of a product is improved and optimized, metal magnesium is dissolved in situ by adopting acidic electrolyte, so that the rutile ruthenium dioxide catalyst with introduced cation vacancies is generated, and the activity and the stability of the catalyst are remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of oxygen evolution reaction catalysts, in particular to a method for preparing a rutile ruthenium dioxide catalyst into which cation vacancies are introduced. Background Art

[0002] Hydrogen energy plays a core role in renewable energy and decarbonization of the global energy system due to its advantages of green and clean, high energy density, high safety, and wide application scenarios. However, in the process of hydrogen production by water electrolysis, the oxygen evolution reaction (OER) occurring at the anode seriously affects the efficiency of the cathode hydrogen evolution reaction due to its slow four-electron kinetics and high energy barrier, which restricts the development of energy conversion and storage. Therefore, the design and preparation of highly active oxygen evolution reaction functional catalyst materials is the key to promoting its practical application. At present, in the field of electrochemical catalytic material design and synthesis, the research on defect regulation mainly focuses on anion defect regulation (e.g., oxygen vacancies, sulfur vacancies, phosphorus vacancies, etc.), while there is little work on regulating microstructure through cation defects. Compared with anion defect regulation, cation defects have higher generation energy, more complex formation process and greater energy consumption, and the challenge of defect concentration is also challenging. It is worth noting that cation vacancies have the advantages of high conductivity, regulation of the adsorption process of intermediates, and regulation of 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 method for preparing a rutile ruthenium dioxide catalyst with introduced cation vacancies. Firstly, a magnesium metal-doped ruthenium dioxide nanoparticle precursor catalyst having an ordered lattice structure and a smaller particle size is prepared by a hydrothermal method and annealing treatment. Then, the metallic magnesium in the precursor catalyst is dissolved by in-situ electrochemical means to generate a rutile ruthenium dioxide catalyst with introduced cation vacancies. The activity and stability of the catalyst are significantly improved.

[0004] The technical solution of the present invention is: A method for preparing a rutile ruthenium dioxide catalyst with introduced cationic vacancies, specifically comprising the following steps: (1) Dissolve glucose and urea in ultrapure water and perform ultrasonic treatment to obtain a uniform transparent mixed solution; (2) Adding hydrated ruthenium trichloride and magnesium compound into a uniform transparent mixed solution, and stirring to dissolve, to obtain a brown-black mixed solution; (3) hydrothermally treating the brown-black mixed solution at 120-150 °C for 8-10 hours to obtain a porous foam precursor; (4) annealing the porous foam precursor to obtain a magnesium-doped ruthenium dioxide nanoparticle precursor catalyst; (5) Under acidic electrolyte conditions, the ruthenium dioxide nanoparticle precursor catalyst is activated by CV cycle to obtain a rutile ruthenium dioxide catalyst with introduced cation vacancies.

[0005] The mass ratio of glucose to urea is 5:0.5-1.5.

[0006] The magnesium compound is magnesium nitrate or magnesium chloride.

[0007] The mass ratio of the hydrated ruthenium trichloride to the magnesium compound is 3-5:1.

[0008] The porous foam precursor is annealed in air, with an annealing heating rate of 5 to 10°C / min, an annealing temperature of 500 to 600°C, and an annealing holding time of 10 to 14 hours.

[0009] The specific steps of performing CV cycle activation on the ruthenium dioxide nanoparticle precursor catalyst under acidic electrolyte conditions are as follows: adding the magnesium metal-doped ruthenium dioxide nanoparticle precursor catalyst to a solvent and performing ultrasonic homogenization treatment, then adding a small amount of perfluorosulfonic acid solution thereto, and then performing ultrasonic homogenization treatment to obtain a uniform slurry, and then dropping the uniform slurry onto a glassy carbon electrode, and using it as a working electrode after natural drying, and using a platinum mesh electrode as a counter electrode and a silver chloride electrode as a reference electrode, and performing CV cycle activation under acidic electrolyte conditions. After the CV cycle activation is completed, the slurry on the glassy carbon electrode is cleaned and dried to obtain a rutile ruthenium dioxide catalyst with introduced cation vacancies.

[0010] The solvent is a mixed solution of water and ethanol, and the volume ratio of water to ethanol is 3:1.

[0011] The acidic electrolyte is a sulfuric acid solution with a concentration of 0.1-1 mol / L.

[0012] The scanning rate of the CV cycle activation is 5 mV / s, the applied voltage range is 1.2~1.4 V vs. RHE, and the number of CV cycle activations is 20~50 times.

[0013] Advantages of the present invention: (1) The present invention introduces magnesium metal atoms into the precursor catalyst, significantly reducing the size of ruthenium dioxide nanoparticles (about 10 nanometers), thereby increasing the specific surface area and the exposed area of ​​the active sites. In addition, the magnesium metal atoms can be dissolved in situ under acidic electrolyte conditions to generate a rutile ruthenium dioxide catalyst with introduced cation vacancies.

[0014] (2) The present invention forms an ordered lattice structure of magnesium-doped ruthenium dioxide nanoparticles through continuous hydrothermal and annealing treatment, thereby improving and optimizing the catalytic performance of the product.

[0015] (3) The rutile ruthenium dioxide catalyst with introduced cation vacancies prepared by the present invention can significantly reduce the overpotential of the oxygen evolution reaction, significantly improve the activity of the oxygen evolution reaction, and has excellent oxygen evolution reaction stability.

[0016] (4) The raw material cost of the present invention is low and easy to obtain, the preparation method is simple, the preparation time is short, and it is easy to experiment and industrially promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This 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.

[0018] Figure 2 This 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.

[0019] Figure 3 This is a high-angle annular dark field scanning lens (HADDF-STEM) image of the rutile ruthenium dioxide catalyst with introduced cation vacancies prepared in Example 1 of the present invention.

[0020] Figure 4 It is a transmission electron microscope (TEM) image of the rutile ruthenium dioxide catalyst prepared in Comparative Example 1 of the present invention.

[0021] Figure 5 It is a linear sweep voltammetry (LSV) curve diagram of the rutile ruthenium dioxide catalyst with introduced cation vacancies prepared in Example 1 of the present invention, the rutile ruthenium dioxide catalyst prepared in Comparative Example 1, and commercial ruthenium dioxide.

[0022] Figure 6 It is a constant current life stability test graph of the rutile ruthenium dioxide catalyst with introduced cationic vacancies prepared in Example 1 of the present invention, the rutile ruthenium dioxide catalyst prepared in Comparative Example 1, and commercial ruthenium dioxide. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example 1

[0024] A method for preparing a rutile ruthenium dioxide catalyst with introduced cationic vacancies, specifically comprising the following steps: (1) Dissolve 10 g glucose and 2 g urea in 10 mL ultrapure water and ultrasonicate for 30 min to obtain a homogeneous transparent mixed solution; (2) Add 105.6 mg of hydrated ruthenium trichloride and 28.53 mg of magnesium nitrate to the homogeneous transparent mixed solution and stir thoroughly for 30 minutes to dissolve to obtain a brown-black mixed solution; (3) The brown-black mixed solution was subjected to a hydrothermal reaction at 140 °C for 8 hours to obtain a porous foam precursor; (4) Transfer the porous foam precursor to a reaction boat, and then place the reaction boat in a muffle furnace for annealing. 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-doped ruthenium dioxide nanoparticle precursor catalyst; (5) Under acidic electrolyte conditions, the ruthenium dioxide nanoparticle precursor catalyst was subjected to CV cycle activation. Specifically, 5 mg of magnesium metal-doped ruthenium dioxide nanoparticle precursor catalyst was added to 1 mL of solvent (a mixed solution of water and ethanol with a volume ratio of 3:1) and subjected to ultrasonic homogenization. Then, 30 μL of perfluorosulfonic acid solution (for increasing the viscosity of the slurry) was added thereto. Subsequently, ultrasonic homogenization was performed to obtain a uniform slurry. Then, 5 μL of the uniform slurry was transferred with a micropipette and dropped onto a glassy carbon electrode with a diameter of 3 mm. After natural drying, it was used as a working electrode. A platinum mesh electrode was used as a counter electrode, and a silver chloride electrode was used as a reference electrode. CV cycle activation was performed under 0.5 mol / L H2SO4 electrolyte solution. The scan rate of CV cycle activation was 5 mV / s, and the applied voltage range was 1.2~1.4 V. vs.RHE, the number of CV cycle activations is 20 to 50 times. After the CV cycle activation, the slurry on the glassy carbon electrode is cleaned and dried to obtain a rutile ruthenium dioxide catalyst with introduced cation vacancies, which is marked as MgRuO2.

[0025] Figure 1 The SEM (100 nm) image of the magnesium metal-doped ruthenium dioxide nanoparticle precursor catalyst prepared in step (4) is Figure 1 It can be seen that the nanoparticle size of the magnesium metal-doped ruthenium dioxide nanoparticle precursor catalyst is about 10 nm, and the introduction of magnesium metal atoms significantly reduces the size of the ruthenium dioxide nanoparticles.

[0026] Figure 2HRTEM image of the magnesium metal-doped ruthenium dioxide nanoparticle precursor catalyst prepared in step (4). Figure 2 It can be seen that the exposed active surfaces of the magnesium metal-doped ruthenium dioxide nanoparticle precursor catalyst are (110) and (101) active surfaces.

[0027] Figure 3 This is the HADDF-STEM image of the rutile ruthenium dioxide catalyst with introduced cation vacancies prepared in step (5). Figure 3 It can be seen that there are obvious atomic vacancies in the regular atomic sequence. This is because the introduced magnesium atoms are dissolved in situ under acidic electrolyte conditions, thereby detaching from the crystal lattice to form cation vacancies. Comparative Example 1

[0028] A method for preparing a ruthenium dioxide catalyst of the ruthenium type, wherein step (1) is the same as step (1) of Example 1, step (2) is to directly add 105.6 mg of hydrated ruthenium trichloride into a uniform transparent mixed solution, and stir the mixture for 30 minutes to dissolve the mixture, thereby obtaining a mixed solution, steps (3) and (4) are the same as steps (3) and (4) of Example 1, and the product of step (4) is a ruthenium dioxide catalyst of the ruthenium type, which is labeled as p-RuO2.

[0029] Figure 4 TEM (100 nm) image of the ruthenium dioxide catalyst prepared in step (4) of comparative example 1. Figure 1 and Figure 4 It can be seen that the introduction of magnesium nitrate can significantly reduce the nanoparticle size of the catalyst product. Performance Analysis:

[0030] 1. The product of Example 1 (MgRuO2), the product of Comparative Example 1 (p-RuO2) and commercial ruthenium dioxide (com-RuO2) were subjected to OER performance tests. The tests were all carried out on a Shanghai Chenhua CHI 760E electrochemical workstation equipped with a typical three-electrode system. The OER performance of the three catalysts was tested in a 0.5 mol / L H2SO4 electrolyte solution. The three catalysts (5 mg each) were added to 1 mL of solvent (a mixed solution of water and ethanol with a volume ratio of 3:1) and ultrasonically homogenized. Then, 30 μL of perfluorosulfonic acid solution was added thereto, followed by ultrasonic homogenization to obtain a uniform slurry. Then, 5 μL of the uniform slurry was transferred with a micropipette and dropped onto a glassy carbon electrode with a diameter of 3 mm. After natural drying, it was used as a working electrode, and a platinum mesh electrode was used as a counter electrode and a silver chloride electrode as a reference electrode. The OER performance test was carried out under the condition of 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 of the OER performance test is shown in Figure 5 , Figure 5 The horizontal axis is the test voltage, and the vertical axis is the current density (in mA / cm 2 ).

[0031] from Figure 5 It can be seen that at 10 mA / cm 2 At a current density of , the overpotential of com-RuO2 is 340 mV (the overpotential is obtained by subtracting the standard electrode potential of water decomposition 1.23 V from the test voltage), the overpotential of p-RuO2 is 296 mV, and the overpotential of MgRuO2 is as low as 216 mV. This shows that the rutile ruthenium dioxide catalyst with introduced 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.

[0032] 2. The product of Example 1 (MgRuO2), the product of Comparative Example 1 (p-RuO2) and commercial ruthenium dioxide (com-RuO2) were subjected to constant current stability tests. The tests were all conducted on a Shanghai Chenhua CHI 760E electrochemical workstation. The stability of the three catalysts was tested in a 0.5 mol / L H2SO4 electrolyte solution. The three catalysts (5 mg each) were added to 1 mL of solvent (a mixed solution of water and ethanol with a volume ratio of 3:1) and ultrasonically homogenized. Then, 30 μL of perfluorosulfonic acid solution was added thereto, and then ultrasonically homogenized again to obtain a uniform slurry. Then, 14.2 μL of the uniform slurry was transferred with a micropipette and dropped to an area of ​​0.2 cm 2The carbon paper was dried naturally as the working electrode, and a platinum mesh electrode was used as the counter electrode and a silver chloride electrode as the reference electrode. The constant current stability test was carried out under the condition of 0.5 mol / L H2SO4 electrolyte solution. That is, at the set constant current density, the relationship between the voltage and time was observed. The constant current (10 mA / cm 2 ) Life stability test results are shown in Figure 6 , Figure 6 The horizontal axis is time (in hours), and the vertical axis is the test voltage.

[0033] from Figure 6 It can be seen that at 10 mA / cm 2 At a current density of , com-RuO2 has a stable operation time of 10 hours, p-RuO2 has a stable operation time of 20 hours, and MgRuO2 can stably operate for 400 hours without obvious performance degradation. This shows that the rutile ruthenium dioxide catalyst with introduced cation vacancies prepared in Example 1 of the present invention exhibits excellent stability in the oxygen evolution reaction.

[0034] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a rutile ruthenium dioxide catalyst with introduced cationic vacancies, characterized in that: The specific steps include: (1) Dissolve glucose and urea in ultrapure water and perform ultrasonic treatment to obtain a uniform transparent mixed solution; (2) Adding hydrated ruthenium trichloride and magnesium compound into a uniform transparent mixed solution, and stirring to dissolve, to obtain a brown-black mixed solution; (3) hydrothermally treating the brown-black mixed solution at 120-150 °C for 8-10 hours to obtain a porous foam precursor; (4) annealing the porous foam precursor to obtain a magnesium-doped ruthenium dioxide nanoparticle precursor catalyst; (5) Under acidic electrolyte conditions, the ruthenium dioxide nanoparticle precursor catalyst is activated by CV cycle to obtain a rutile ruthenium dioxide catalyst with introduced cation vacancies.

2. The method for preparing a rutile ruthenium dioxide catalyst with introduced cationic vacancies according to claim 1, characterized in that: The mass ratio of glucose to urea is 5:0.5-1.

5.

3. The method for preparing a rutile ruthenium dioxide catalyst with introduced cationic vacancies according to claim 1, characterized in that: The magnesium compound is magnesium nitrate or magnesium chloride.

4. The method for preparing a rutile ruthenium dioxide catalyst with introduced cationic vacancies according to claim 1, characterized in that: The mass ratio of the hydrated ruthenium trichloride to the magnesium compound is 3-5:

1.

5. The method for preparing a rutile ruthenium dioxide catalyst with introduced cationic vacancies according to claim 1, characterized in that: The porous foam precursor is annealed in air, with an annealing heating rate of 5 to 10°C / min, an annealing temperature of 500 to 600°C, and an annealing holding time of 10 to 14 hours.

6. The method for preparing a rutile ruthenium dioxide catalyst with introduced cationic vacancies according to claim 1, characterized in that: The specific steps of performing CV cycle activation on the ruthenium dioxide nanoparticle precursor catalyst under acidic electrolyte conditions are as follows: adding magnesium metal-doped ruthenium dioxide nanoparticle precursor catalyst powder to a solvent and performing ultrasonic homogenization treatment, then adding a small amount of perfluorosulfonic acid solution thereto, and then performing ultrasonic homogenization treatment to obtain a uniform slurry, and then dropping the uniform slurry onto a glassy carbon electrode, and using it as a working electrode after natural drying, and using a platinum mesh electrode as a counter electrode and a silver chloride electrode as a reference electrode, and performing CV cycle activation under acidic electrolyte conditions. After the CV cycle activation is completed, the slurry on the glassy carbon electrode is cleaned and dried to obtain a rutile ruthenium dioxide catalyst with introduced cation vacancies.

7. The method for preparing a rutile ruthenium dioxide catalyst with introduced cationic vacancies according to claim 6, characterized in that: The solvent is a mixed solution of water and ethanol, and the volume ratio of water to ethanol is 3:

1.

8. The method for preparing a rutile ruthenium dioxide catalyst with introduced cationic vacancies according to claim 6, characterized in that: The acidic electrolyte is a sulfuric acid solution with a concentration of 0.1-1 mol / L.

9. The method for preparing a rutile ruthenium dioxide catalyst with introduced cationic vacancies according to claim 6, characterized in that: The scanning rate of the CV cycle activation is 5 mV / s, the applied voltage range is 1.2~1.4 V vs. RHE, and the number of CV cycle activations is 20~50 times.

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