Ruthenium cobalt oxide self-supporting electrode and preparation method and application thereof

Abstract

The invention relates to the technical field of electrocatalysts, in particular to a ruthenium cobalt oxide self-supporting electrode and a preparation method and application thereof. A titanium mesh is used as a substrate, a hydrochloric acid aqueous solution of ruthenium chloride and cobalt chloride grows ruthenium dioxide nanoparticles in situ on the titanium mesh through a hydrothermal method, cobalt atoms are doped into ruthenium dioxide crystal lattices, and a self-supporting electrode of cobalt doped ruthenium dioxide is formed and used as an electrocatalyst for oxygen evolution reaction and hydrogen evolution reaction. A catalytic material grows in situ on a three-dimensional porous conductive substrate, a self-supporting catalyst is prepared, a binder is not needed, the specific surface area is larger, more active sites can be exposed, the activity and stability of the material are further improved, low-electronegativity cobalt provides electrons for ruthenium through adjustment of doped elements, excessive oxidation of ruthenium is inhibited, and the performance of the catalyst is improved. The activity and stability of the catalyst are improved to a certain extent, so that the catalyst has good performance under high current density, is prepared by using a hydrothermal method, is simple and controllable in process, and can be widely applied to water electrolysis devices.

Description

Technical Field

[0001] The present invention relates to the technical field of electrocatalysts, and in particular to a ruthenium cobalt oxide self-supporting electrode, a preparation method and an application thereof. Background Art

[0002] With the series of environmental problems brought about by the extensive use of fossil fuels, the development of clean and renewable energy has become urgent. As a green, pollution-free and sustainable hydrogen production method, water electrolysis is considered to be an ideal hydrogen production method. Compared with traditional alkaline water electrolysis, acidic water electrolysis has the advantages of high gas purity, high operating current density and low energy consumption, making it an efficient hydrogen production technology. Acidic electrocatalysts are usually based on precious metals. Among them, ruthenium-based catalysts have been regarded as candidate materials to replace iridium due to their high catalytic activity, lower cost and larger storage capacity. However, at high potentials, ruthenium-based materials are easily oxidized and dissolved, affecting their performance. In recent years, many water electrolysis catalysts have been studied and developed. However, most catalysts have low current density and cannot meet the requirements of industrial water electrolysis for hydrogen production. Therefore, the preparation of low-cost, high-performance electrocatalysts that can achieve high current density catalysis is of great significance for promoting the practical application of water electrolysis for hydrogen production. Summary of the Invention

[0003] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides a ruthenium cobalt oxide self-supporting electrode and a preparation method and application thereof to solve the problems involved in the background technology.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a ruthenium cobalt oxide self-supporting electrode, which uses a titanium mesh as a substrate, and a hydrochloric acid aqueous solution of ruthenium chloride and cobalt chloride is used to in situ grow ruthenium dioxide nanoparticles on the titanium mesh through a hydrothermal method. Cobalt atoms are incorporated into the ruthenium dioxide lattice to form a cobalt-doped ruthenium dioxide self-supporting electrode, which is used as an electrocatalyst for oxygen evolution reaction and hydrogen evolution reaction.

[0005] Preparation method of ruthenium cobalt oxide self-supporting electrode,

[0006] 1) Place the cut titanium mesh in the cleaning solution and ultrasonically clean it; immerse the ultrasonicated titanium mesh in a hydrochloric acid solution for etching; then rinse with the cleaning solution and dry it;

[0007] 2) adding ruthenium chloride and cobalt chloride to the hydrochloric acid solution and stirring thoroughly at room temperature to dissolve;

[0008] 3) Taking a piece of titanium mesh treated in 1), immersing it in the solution of 2), and then transferring it together to a polytetrafluoroethylene-lined reactor for reaction. After cooling to room temperature, the titanium mesh is removed, rinsed, and dried to obtain a ruthenium cobalt oxide self-supporting electrode.

[0009] Further,

[0010] In the above 1), the titanium mesh is sequentially placed in acetone, ethanol and deionized water for cleaning, and then rinsed with ethanol and deionized water after etching.

[0011] Furthermore, in the above 1), ultrasonic treatment was performed for 10 minutes, etching was performed at 90° C. for 15 minutes, and drying was performed at 60° C. for 6 hours, and the mass fraction of the hydrochloric acid solution was 18%.

[0012] Furthermore, the mass fraction of the hydrochloric acid solution in 2) is 0.5%, the molar ratio of ruthenium chloride to cobalt chloride is 1:1.74, the concentration of ruthenium chloride is 38.6 mM, and the concentration of cobalt chloride is 67.2 mM.

[0013] Furthermore, in the above 3), the reaction conditions are 200° C. for 20 h, washing with deionized water and ethanol alternately, and drying at 60° C. for 6 h.

[0014] The invention discloses an application of a ruthenium cobalt oxide self-supporting electrode for oxygen evolution reaction, hydrogen evolution reaction and complete water splitting.

[0015] Further,

[0016] 1) Using a cobalt ruthenium oxide self-supporting electrode as the working electrode, its oxygen and hydrogen evolution performance was tested in a three-electrode system;

[0017] 2) Assemble the cobalt ruthenium oxide self-supporting electrode into a complete water splitting device.

[0018] Furthermore, the working electrode in the three-electrode system described in 1) is a cobalt ruthenium oxide self-supporting electrode, and the size is 1*1 cm, the reference electrode and the counter electrode are a reversible hydrogen electrode and a platinum sheet electrode, respectively, and the electrolyte used in the test is 0.5MH2SO4 solution.

[0019] Furthermore, the full water splitting device described in 2) is a dual-electrode electrocatalytic electrolyzer, the anode and cathode are both cobalt ruthenium oxide self-supporting electrodes, and the size of each is 1*1 cm, and the test electrolyte is 0.5M H2SO4 solution.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention in situ grows catalytic materials on a three-dimensional porous conductive substrate to prepare a self-supporting catalyst, which does not require a binder and has a larger specific surface area, capable of exposing more active sites, further improving the activity and stability of the material. By adjusting the doping elements, the low-electronegativity cobalt provides electrons for ruthenium, inhibiting the excessive oxidation of ruthenium, and to a certain extent improving the activity and stability of the catalyst, so that it has good performance under high current density. It is prepared by a hydrothermal method, which is simple and controllable, does not require expensive equipment, has the potential for large-scale application, and can be widely used in water electrolysis devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a SEM image of a cobalt ruthenium oxide self-supporting electrode according to an embodiment of the present invention;

[0023] Figure 2 is a TEM image of a cobalt ruthenium oxide self-supporting electrode according to an embodiment of the present invention;

[0024] Figure 3 is a HRTEM image of a cobalt ruthenium oxide self-supporting electrode according to an embodiment of the present invention;

[0025] Figure 4 The OER polarization curves of the cobalt ruthenium oxide self-supporting electrode of the embodiment of the present invention, the product obtained in the comparative example, and the commercial RuO2 catalyst in acidic electrolyte;

[0026] Figure 5 HER polarization curves of the cobalt ruthenium oxide self-supporting electrode of the embodiment of the present invention, the product obtained in the comparative example, and the commercial Pt / C catalyst in acidic electrolyte;

[0027] Figure 6 This is a performance diagram of the full water splitting of the electrolytic water device assembled with the cobalt ruthenium oxide self-supporting electrode of the embodiment of the present invention and the electrolytic water device assembled with the commercial RuO2 catalyst and the commercial Pt / C catalyst. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0029] Example 1:

[0030] A ruthenium cobalt oxide self-supporting electrode is used. It uses a titanium mesh as a substrate. Ruthenium dioxide nanoparticles are grown in situ on the titanium mesh using a hydrochloric acid aqueous solution of ruthenium chloride and cobalt chloride through a hydrothermal method. Cobalt atoms are doped into the ruthenium dioxide lattice to form a cobalt-doped ruthenium dioxide self-supporting electrode, which is used as an electrocatalyst for oxygen evolution reaction and hydrogen evolution reaction.

[0031] Preparation method of ruthenium cobalt oxide self-supporting electrode,

[0032] 1) Place the cut titanium mesh in acetone, ethanol, and deionized water, and ultrasonicate for 10 minutes each. Prepare an 18% hydrochloric acid solution, immerse the ultrasonicated titanium mesh in the solution, and etch at 90°C for 15 minutes. Rinse with ethanol and deionized water, and place in a 60°C oven to dry for 6 hours.

[0033] 2) Prepare 50 ml of 0.5% hydrochloric acid solution; weigh 1.93 mmol of ruthenium chloride and 3.36 mmol of cobalt chloride, add them to the hydrochloric acid solution, and stir thoroughly at room temperature to dissolve.

[0034] 3) Take a piece of titanium mesh treated in 1) and immerse it in the prepared solution. Then transfer the mixture to a polytetrafluoroethylene-lined reactor and react at 200°C for 20 hours. After cooling to room temperature, remove the titanium mesh and rinse it alternately with deionized water and ethanol. Then, dry it in a 60°C oven for 6 hours to obtain the final product.

[0035] Figure 1 This is a SEM image of a cobalt ruthenium oxide free-standing electrode. The image shows that ruthenium dioxide nanoparticles are successfully loaded on the titanium mesh.

[0036] Figure 2 This is a TEM image of a cobalt ruthenium oxide free-standing electrode, showing that ruthenium dioxide nanoparticles are evenly distributed on the titanium mesh.

[0037] Figure 3 This is the HRTEM of a cobalt ruthenium oxide self-supporting electrode. The lattice fringe spacing of 0.319 nm corresponds to the Ru(110) surface, and the lattice fringe spacing of 0.325 nm corresponds to the Ti(110) surface.

[0038] Example 2:

[0039] The invention discloses an application of a ruthenium cobalt oxide self-supporting electrode for oxygen evolution reaction, hydrogen evolution reaction and complete water splitting.

[0040] 1) The oxygen and hydrogen evolution performance of a cobalt ruthenium oxide self-supporting electrode was tested in a three-electrode system using a cobalt ruthenium oxide self-supporting electrode as the working electrode, and the working electrode in the three-electrode system was a cobalt ruthenium oxide self-supporting electrode with a size of 1*1 cm. The reference electrode and counter electrode were a reversible hydrogen electrode and a platinum electrode, respectively. The electrolyte used in the test was 0.5M H2SO4 solution.

[0041] 2) The cobalt-ruthenium oxide self-supporting electrodes were assembled into a complete water splitting device. The complete water splitting device was a two-electrode electrocatalytic electrolyzer, with both the anode and cathode being cobalt-ruthenium oxide self-supporting electrodes, each measuring 1 x 1 cm. The test electrolyte was a 0.5 M H2SO4 solution.

[0042] Comparative Example 1:

[0043] 1) The same as step (1) in the preparation method of Example 1, to obtain a treated titanium mesh substrate.

[0044] 2) Prepare 50 ml of 0.5% hydrochloric acid solution; weigh 1.93 mmol of ruthenium chloride and add it to the hydrochloric acid solution, stirring thoroughly at room temperature to dissolve.

[0045] 3) The final product obtained is consistent with step (3) in the preparation method of Example 1, and is a ruthenium oxide electrocatalyst grown in situ on the titanium mesh.

[0046] Comparative Example 2:

[0047] 1) The same as step (1) in the preparation method of Example 1, to obtain a treated titanium mesh substrate.

[0048] 2) Prepare 50 ml of 0.5% hydrochloric acid solution; weigh 3.36 mmol of cobalt chloride and add it to the hydrochloric acid solution, stirring thoroughly at room temperature to dissolve.

[0049] 3) The final product obtained is consistent with step (3) of the preparation method of Example 1, and is a cobalt oxide electrocatalyst grown in situ on the titanium mesh.

[0050] Performance testing:

[0051] 1) A three-electrode system was used, with the electrolyte being 0.5M H2SO4 solution. A reversible hydrogen electrode and a platinum electrode were used as the reference electrode and counter electrode, respectively, and the prepared electrocatalyst was directly used as the working electrode. Linear sweep voltammetry (LSV) was used to evaluate the OER performance of the catalyst with IR compensation. The test results are shown in Figure 1. Figure 4 As shown. In 0.5MH2SO4 electrolyte, an overpotential of 455V is required to reach 1000mA cm -2 The current density is higher than that of the comparative example and commercial RuO2, and the catalytic performance is also significantly better than that of the comparative example and commercial RuO2.

[0052] The HER catalytic activity was tested in 0.5M H2SO4 electrolyte. Figure 5 As mentioned above, an overpotential of 365 V is required to achieve 1000 mA cm -2 The current density is higher than that of the control and commercial Pt / C.

[0053] 2) The cobalt ruthenium oxide self-supporting electrode obtained above was assembled into a two-electrode electrolytic cell, and its water splitting performance was tested under acidic conditions. Figure 6 As shown, only a small voltage of 1.45V is required to achieve 10mA cm -2 The current density is much lower than that of the commercial RuO2 and Pt / C electrolytic cell (1.50V).

[0054] While 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 these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A ruthenium cobalt oxide self-supporting electrode, characterized in that: Using titanium mesh as substrate, ruthenium chloride and cobalt chloride hydrochloric acid aqueous solution are used to in situ grow ruthenium dioxide nanoparticles on the titanium mesh through a hydrothermal method. Cobalt atoms are doped into the ruthenium dioxide lattice to form a cobalt-doped ruthenium dioxide self-supporting electrode, which is used as an electrocatalyst for oxygen evolution reaction and hydrogen evolution reaction.

2. The method for preparing a ruthenium cobalt oxide self-supporting electrode according to claim 1, characterized in that: 1) Place the cut titanium meshes into the cleaning solution one by one and perform ultrasonic cleaning respectively; The ultrasonic titanium mesh is immersed in a hydrochloric acid solution for etching; then it is rinsed with a cleaning solution and dried; 2) adding ruthenium chloride and cobalt chloride into the hydrochloric acid solution and stirring thoroughly to dissolve at room temperature; 3) Take a piece of titanium mesh treated in 1), immerse it in the solution of 2), and then transfer them together to a polytetrafluoroethylene-lined reactor for reaction. After cooling to room temperature, take out the titanium mesh, rinse it, and dry it to obtain a ruthenium cobalt oxide self-supporting electrode.

3. The method for preparing the ruthenium cobalt oxide self-supporting electrode according to claim 2, characterized in that: In the above 1), the titanium mesh is sequentially placed in acetone, ethanol and deionized water for cleaning, and then rinsed with ethanol and deionized water after etching.

4. The method for preparing a ruthenium cobalt oxide self-supporting electrode according to claim 2, characterized in that: In the above 1), ultrasonic treatment is performed for 10 minutes, etching is performed at 90° C. for 15 minutes, and drying is performed at 60° C. for 6 hours. The mass fraction of the hydrochloric acid solution is 18%.

5. The method for preparing a ruthenium cobalt oxide self-supporting electrode according to claim 2, characterized in that: The mass fraction of the hydrochloric acid solution in the above 2) is 0.5%, the molar ratio of ruthenium chloride to cobalt chloride is 1:1.74, the concentration of ruthenium chloride is 38.6 mM, and the concentration of cobalt chloride is 67.2 mM.

6. The method for preparing a ruthenium cobalt oxide self-supporting electrode according to claim 2, characterized in that: In the above 3), the reaction conditions are 200° C. for 20 h, washing with deionized water and ethanol alternately, and drying at 60° C. for 6 h.

7. Use of the ruthenium cobalt oxide self-supporting electrode according to claim 1, wherein the electrode is prepared according to the preparation method according to any one of claims 2 to 6, characterized in that: Used in oxygen evolution reaction, hydrogen evolution reaction and complete water splitting.

8. The use of the ruthenium cobalt oxide self-supporting electrode according to claim 7, characterized in that: 1) Using the cobalt ruthenium oxide self-supporting electrode as the working electrode, its oxygen and hydrogen evolution performance was tested in a three-electrode system; 2) Assemble the cobalt ruthenium oxide self-supporting electrode into a complete water splitting device.

9. The use of the ruthenium cobalt oxide self-supporting electrode according to claim 8, characterized in that: The working electrode in the three-electrode system described in 1) is a cobalt ruthenium oxide self-supporting electrode, and the size is 1*1 cm, the reference electrode and the counter electrode are a reversible hydrogen electrode and a platinum sheet electrode, respectively, and the electrolyte used in the test is a 0.5M H2SO4 solution.

10. The use of the ruthenium cobalt oxide self-supporting electrode according to claim 8, characterized in that: 2) The full water splitting device described in is a double-electrode electrocatalytic electrolyzer, the anode and cathode are both cobalt ruthenium oxide self-supporting electrodes, and the size of each is 1*1 cm, and the test electrolyte is 0.5M H2SO4 solution.

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