Hollow framework high entropy oxide oxygen evolution catalyst and preparation method thereof and oxygen evolution electrode

Abstract

The present application belongs to the technical field of water electrolysis catalysts, and in particular relates to a hollow framework high-entropy oxide oxygen evolution catalyst, a preparation method thereof, and an oxygen evolution electrode. The present application provides a hollow framework high-entropy oxide oxygen evolution catalyst having a hollow framework structure and a large specific surface area. It can provide more active sites during the water electrolysis oxygen evolution reaction, making oxygen more easily released, thereby improving the oxygen evolution catalytic activity of the catalyst, and providing a more superior oxygen evolution catalytic performance per unit mass of the catalyst, thereby solving the technical problem in the prior art that the high-entropy oxide has a low surface area and provides an insufficient number of active sites during the oxygen evolution reaction.

Description

Technical Field

[0001] The present application belongs to the technical field of water electrolysis catalysts, and in particular relates to a hollow framework high entropy oxide oxygen evolution catalyst, a preparation method thereof, and an oxygen evolution electrode. Background Art

[0002] The energy and environmental crises caused by the long-term use of fossil fuels are receiving more and more attention, and the development and storage of green new energy has become an urgent need at present; hydrogen is generally considered to be an ideal energy carrier due to its high energy density and environmental friendliness.

[0003] Industrial coal gasification and partial oxidation processes for hydrogen production both generate carbon dioxide emissions, contributing to an enhanced greenhouse effect. Water electrolysis, on the other hand, produces hydrogen and oxygen without carbon dioxide, making it a relatively efficient and environmentally friendly approach. Hydrogen production from water electrolysis involves the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). The theoretical reaction potential of the HER is 0 V, while that of the OER is as high as 1.23 V (with respect to the reversible hydrogen electrode, RHE). Therefore, the OER is the primary limiting reaction for hydrogen production from water electrolysis. Suitable OER catalysts can effectively lower the reaction overpotential, bringing it closer to the theoretical potential, thereby reducing reaction energy consumption and improving the economic benefits of hydrogen production from water electrolysis. Ruthenium, iridium, and their oxides are the most commonly used catalysts for the OER, offering low reaction barriers and excellent catalytic performance. However, both ruthenium and iridium are precious metals with limited resource reserves and high costs, limiting their continued development. In recent years, there has been considerable research on non-precious metal OER catalysts, but most have high overpotentials and substandard performance. Studying ruthenium and iridium-based catalysts, especially multi-component oxide materials of ruthenium and iridium with other transition metals, is an effective way to reduce the amount of precious metals used while improving catalyst performance and stability.

[0004] High-entropy oxides (HEOs) have attracted the attention of many researchers as emerging electrocatalytic materials. Their wide elemental composition and fully adjustable element ratios give them a nearly continuous binding energy range, making them very promising OER catalysts. However, current research on HEOs mainly focuses on the regulation and improvement of elemental composition, with less improvement on the structure of HEOs. HEOs have a low surface area and provide an insufficient number of active sites for the oxygen evolution reaction. Summary of the Invention

[0005] In view of this, the present application provides a hollow framework high-entropy oxide oxygen evolution catalyst, a preparation method thereof, and an oxygen evolution electrode, which are used to solve the technical problems in the prior art that the surface area of ​​high-entropy oxide is low and the number of active sites provided during the oxygen evolution reaction is insufficient.

[0006] In a first aspect, the present application provides a hollow framework high entropy oxide oxygen evolution catalyst, wherein the hollow framework high entropy oxide oxygen evolution catalyst comprises ZnFeNiCuCo and RuO2;

[0007] The RuO2 and the ZnFeNiCuCo are composited to form a hollow framework structure.

[0008] Preferably, the particle size of the hollow framework high entropy oxide oxygen evolution catalyst is 100 to 300 nm.

[0009] Preferably, the second aspect of the present application provides a method for preparing a hollow framework high entropy oxide oxygen evolution catalyst, the preparation method comprising the steps of:

[0010] Step S1, adding an organic solution containing dimethylimidazole and acetylacetone metal organic compound dropwise to an organic solution of zinc nitrate hexahydrate, stirring for reaction, and centrifuging to obtain a high entropy compound precipitate;

[0011] Step S2, subjecting the washed high entropy compound precipitate to a carbonization reduction reaction to obtain a carbonized ZnFeNiCuCo precursor;

[0012] Step S3, stirring the carbonized ZnFeNiCuCo precursor and ruthenium salt in an aqueous solution, and centrifuging to obtain ZnFeNiCuCo-Ru;

[0013] Step S4, placing the ZnFeNiCuCo-Ru in air for a pyrolysis reaction to obtain a hollow framework high entropy oxide oxygen evolution catalyst;

[0014] In step S1 , the acetylacetonate metal organic compound includes iron acetylacetonate, nickel acetylacetonate, copper acetylacetonate and cobalt acetylacetonate.

[0015] Preferably, in step S1, the stirring reaction time is 12 to 36 hours.

[0016] Preferably, the organic solution containing dimethylimidazole and acetylacetonate metal organic compound contains, calculated in parts by mass, 2850 parts by mass of dimethylimidazole, 56 parts by mass of iron acetylacetonate, 41 parts by mass of nickel acetylacetonate, 41 parts by mass of copper acetylacetonate, and 56 parts by mass of cobalt acetylacetonate;

[0017] The organic solution of zinc nitrate hexahydrate contains 2300 parts by mass of zinc nitrate hexahydrate.

[0018] Preferably, in step S2, the atmosphere of the carbonization reduction reaction is an Ar / H2 atmosphere;

[0019] The temperature of the carbonization reduction reaction is 800-1000° C., and the time is 2-4 hours.

[0020] Preferably, the Ar / H2 atmosphere consists of 90 parts by volume of Ar and 10 parts by volume of H2.

[0021] Preferably, in step S3, the ruthenium salt is ruthenium chloride, and the mass ratio of ruthenium chloride to the carbonized ZnFeNiCuCo precursor is 4:10.

[0022] Preferably, in step S4, the temperature of the pyrolysis reaction is 300-500° C., and the time is 3-5 hours.

[0023] Preferably, the heating rate of the pyrolysis reaction is 5 to 10° C. / min.

[0024] In a third aspect, the present application provides an oxygen evolution electrode, which comprises a substrate and a coating; the coating is the above-mentioned hollow framework high entropy oxide oxygen evolution catalyst.

[0025] The substrate of the oxygen evolution electrode can be various corrodible metals or alloys, preferably titanium alloy.

[0026] In summary, the present application provides a hollow framework high-entropy oxide oxygen evolution catalyst, a preparation method thereof, and an oxygen evolution electrode, wherein the hollow framework high-entropy oxide oxygen evolution catalyst includes ZnFeNiCuCo and RuO2; the RuO2 and the ZnFeNiCuCo are composited to form a high-entropy oxide with a hollow framework structure; compared with the ZnCoFeNiCu catalyst that is not sintered in air and the commercially available RuO2 catalyst, the ZnCoFeNiCu-Ru-O hollow framework high-entropy oxide has a larger specific surface area, can provide more active sites during the electrolysis of water and oxygen evolution reaction, oxygen is more easily precipitated, and the oxygen evolution catalytic activity of the catalyst is improved. The oxygen evolution catalytic performance per unit mass of the catalyst is more superior, thereby solving the technical problem in the prior art that the surface area of ​​the high-entropy oxide is low and the number of active sites provided during the oxygen evolution reaction is insufficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0028] Figure 1 X-ray diffraction patterns of the ZnFeNiCuCo high-entropy alloy, RuO2, and hollow framework high-entropy oxide oxygen evolution catalysts provided in Example 2 of the present application;

[0029] Figure 2This is an electron micrograph of the hollow framework high entropy oxide oxygen evolution catalyst provided in Example 2 of the present application;

[0030] Figure 3 Schematic diagram of the OER performance of the hollow framework high entropy oxide oxygen evolution catalyst provided in Example 2 of the present application in 1M KOH electrolyte (polarization curve obtained by IR correction);

[0031] Figure 4 This is the Tafel slope diagram of the hollow framework high entropy oxide oxygen evolution catalyst provided in Example 2 of the present application in 1M KOH electrolyte. DETAILED DESCRIPTION

[0032] The present application provides a hollow framework high entropy oxide oxygen evolution catalyst, a preparation method thereof, and an oxygen evolution electrode, which are used to solve the technical problems in the prior art of low surface area of ​​high entropy oxide and insufficient number of active sites provided during the oxygen evolution reaction.

[0033] The following will clearly and completely describe the technical solution of this application in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0034] Example 1

[0035] Example 1 of the present application provides a hollow framework high entropy oxide oxygen evolution catalyst, the composition and structure of which are as shown in the attached Figure 1-2 As shown in the attached Figure 1 The X-ray diffraction pattern shows that the hollow framework high entropy oxide oxygen evolution catalyst is composed of ZnFeNiCuCo and RuO2, and the characteristic diffraction peaks at 28°, 35° and 54° are consistent with the diffraction peaks of RuO2 standard card, which indicates that ZnFeNiCuCo and RuO2 are composited to form a high entropy oxide oxygen evolution catalyst; further, from the attached Figure 2 As can be seen from the electron microscope image shown, the high-entropy oxide oxygen evolution catalyst formed by the composite of ZnFeNiCuCo and RuO2 has a hollow framework structure without agglomeration. The high-entropy oxide oxygen evolution catalyst with a hollow framework structure has a larger specific surface area, can provide more active sites during the electrolysis of water and oxygen evolution reaction, oxygen is more easily released, and the oxygen evolution catalytic activity of the catalyst is improved. The oxygen evolution catalytic performance per unit mass of the catalyst is more superior, thereby solving the technical problem in the prior art that the surface area of ​​the high-entropy oxide is low and the number of active sites provided during the oxygen evolution reaction is insufficient.

[0036] For the size and morphology of the hollow framework high entropy oxide oxygen evolution catalyst provided in this application, please refer to the attached Figure 2, are square or star-shaped, without agglomeration, and have a particle size of about 100 to 300 nm. Compared with structures of micron or larger size, nano-sized hollow framework high-entropy oxide oxygen evolution catalysts have a larger specific surface area, can provide more active sites during the oxygen evolution reaction, and improve the oxygen evolution reaction performance.

[0037] Example 2

[0038] Example 2 of the present application provides a preparation method for the hollow framework high-entropy oxide oxygen evolution catalyst described in Example 1, the preparation method including the steps of preparing an organic solution containing dimethylimidazole and acetylacetone metal organic compounds, preparing an organic solution of zinc nitrate hexahydrate, preparing a high-entropy compound precipitate, preparing a carbonized ZnFeNiCuCo precursor, preparing ZnFeNiCuCo-Ru, and conducting a thermal decomposition reaction in air.

[0039] The preparation step of the organic solution containing dimethylimidazole and acetylacetonate metal organic compounds includes dissolving 2.85g of dimethylimidazole, 56mg of cobalt acetylacetonate, 56mg of iron acetylacetonate, 41mg of nickel acetylacetonate, and 41mg of copper acetylacetonate in 100mL of methanol, and ultrasonically treating for 15mins to obtain a dispersion, i.e., an organic solution containing dimethylimidazole and acetylacetonate metal organic compounds;

[0040] The steps of preparing the organic solution of zinc nitrate hexahydrate include ultrasonically mixing 2.3 g of zinc nitrate hexahydrate in 100 mL of methanol, and ultrasonically treating for 15 minutes to obtain a dispersion, namely the organic solution of zinc nitrate hexahydrate;

[0041] The preparation steps of the high entropy compound precipitate include dripping an organic solution containing dimethylimidazole and acetylacetone metal organic compound into an organic solution of zinc nitrate hexahydrate at a rate of 2 to 3 drops per second and stirring for 24 hours, collecting the precipitate by centrifugation, washing it three times with methanol, and drying it at 60° C. to obtain a product, namely the high entropy compound precipitate;

[0042] The preparation steps of the carbonized ZnFeNiCuCo precursor include transferring the high entropy compound precipitate into a porcelain boat, heating it to 950°C at 5°C / min under an Ar / H2 atmosphere, and carbonizing it for 3 hours to obtain a black product, which is the carbonized ZnFeNiCuCo precursor;

[0043] The preparation steps of ZnFeNiCuCo-Ru include adding 100 mg of carbonized ZnFeNiCuCo precursor to 50 mL of distilled water, injecting 4 mL of 10 mg / mL RuCl3 solution, stirring and reacting for 12 hours, collecting the product by centrifugation, washing it twice with anhydrous ethanol, and freeze-drying it to obtain the product, namely ZnFeNiCuCo-Ru;

[0044] The pyrolysis reaction in air includes moving ZnFeNiCuCo-Ru into a porcelain boat, heating it to 400°C at a rate of 10°C / min in an air atmosphere, and pyrolyzing it for 4 hours to obtain a ZnCoFeNiCu-Ru-O hollow framework high entropy oxide.

[0045] Example 3

[0046] Example 3 of the present application provides a method for preparing carbonized ZnFeNiCuCo, which includes the steps of preparing an organic solution containing dimethylimidazole and an acetylacetone metal organic compound, preparing an organic solution of zinc nitrate hexahydrate, preparing a high entropy compound precipitate, and preparing a carbonized ZnFeNiCuCo precursor.

[0047] The preparation step of the organic solution containing dimethylimidazole and acetylacetonate metal organic compounds includes dissolving 2.85g of dimethylimidazole, 56mg of cobalt acetylacetonate, 56mg of iron acetylacetonate, 41mg of nickel acetylacetonate, and 41mg of copper acetylacetonate in 100mL of methanol, and ultrasonically treating for 15mins to obtain a dispersion, i.e., an organic solution containing dimethylimidazole and acetylacetonate metal organic compounds;

[0048] The steps of preparing the organic solution of zinc nitrate hexahydrate include ultrasonically mixing 2.3 g of zinc nitrate hexahydrate in 100 mL of methanol, and ultrasonically treating for 15 minutes to obtain a dispersion, namely the organic solution of zinc nitrate hexahydrate;

[0049] The preparation steps of the high entropy compound precipitate include dripping an organic solution containing dimethylimidazole and acetylacetone metal organic compound into an organic solution of zinc nitrate hexahydrate at a rate of 2 to 3 drops per second and stirring for 24 hours, collecting the precipitate by centrifugation, washing it three times with methanol, and drying it at 60° C. to obtain a product, namely the high entropy compound precipitate;

[0050] The preparation steps of the carbonized ZnFeNiCuCo precursor include transferring the high entropy compound precipitate into a porcelain boat, heating it to 950°C at 5°C / min under an Ar / H2 atmosphere, and carbonizing it for 3 hours to obtain a black product, which is the carbonized ZnFeNiCuCo precursor.

[0051] Example 4

[0052] Example 4 of the present application provides an oxygen evolution electrode, which comprises a substrate and a coating; the coating comprises the hollow framework high entropy oxide oxygen evolution catalyst described in Example 1 or 2, and the substrate can be selected from various corrosion-resistant metals and alloys, preferably titanium alloy.

[0053] An oxygen evolution electrode, which is formed by coating a hollow frame high-entropy oxide oxygen evolution catalyst coating on the substrate surface of the oxygen evolution electrode, an existing hydrogen evolution electrode and an electrolyzer, constitute an electrolytic water system. Since the oxygen evolution catalyst in the oxygen evolution electrode used in the electrolytic water system has a low overpotential, hydrogen production by electrolysis of water is easy, which can reduce energy consumption and has promotion and application value.

[0054] Test Example 1

[0055] This test example provides oxygen evolution performance tests of ZnCoFeNiCu-Ru-O provided in Example 2, ZnFeNiCuCo provided in Example 3, and commercially available RuO2. The oxygen evolution performance test was conducted using a standard three-electrode system on a CHI-750E electrochemical workstation in 1M KOH solution. The test results are shown in the attached manual. Figure 3-4 As shown, Figure 3 is the polarization curve obtained by IR correction, Figure 3 It can be seen that in 1MKOH electrolyte, the current density reaches 10mA / cm 2 When the overpotential of ZnFeNiCuCo provided by Example 3 is the highest, which is 390mV, while the overpotential of RuO2 is 291mV, which is lower than that of ZnFeNiCuCo. This is consistent with the conclusion that RuO2 has excellent oxygen evolution activity in alkaline electrolytes well known to those skilled in the art, indicating the rationality of this experiment. At the same time, the ZnCoFeNiCu-Ru-O provided by Example 2 reaches a current density of 10mA / cm 2 At the same time, by comparing the Tafel slopes of the oxygen evolution performance test results of ZnCoFeNiCu-Ru-O provided in Example 2, ZnFeNiCuCo provided in Example 3, and commercially available RuO2, it can be seen that ZnCoFeNiCu-Ru-O has the lowest Tafel slope of 54mV / dec, while RuO2 has the highest Tafel slope of 108mV / dec, which is also consistent with the overpotentials of ZnCoFeNiCu-Ru-O provided in Example 2, ZnFeNiCuCo provided in Example 3, and commercially available RuO2. ZnCoFeNiCu-Ru-O with a hollow framework structure has a larger specific surface area, can provide more active sites in the process of oxygen evolution reaction in electrolysis of water, oxygen is more easily precipitated, and the oxygen evolution catalytic activity of the catalyst is improved, so that the oxygen evolution potential is reduced and the oxygen evolution activity is improved.

[0056] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a hollow framework high entropy oxide oxygen evolution catalyst, characterized in that: The hollow framework high entropy oxide oxygen evolution catalyst comprises ZnFeNiCuCo and RuO2; The RuO2 and the ZnFeNiCuCo are composited to form a hollow framework structure; The preparation method comprises the steps of: Step S1, adding an organic solution containing dimethylimidazole and acetylacetone metal organic compound dropwise to an organic solution of zinc nitrate hexahydrate, stirring for reaction, and centrifuging to obtain a high entropy compound precipitate; Step S2, subjecting the washed high entropy compound precipitate to a carbonization reduction reaction to obtain a carbonized ZnFeNiCuCo precursor; Step S3, stirring the carbonized ZnFeNiCuCo precursor and ruthenium salt in an aqueous solution, and centrifuging to obtain ZnFeNiCuCo-Ru; Step S4, placing the ZnFeNiCuCo-Ru in air for a pyrolysis reaction to obtain a hollow framework high entropy oxide oxygen evolution catalyst; In step S1 , the acetylacetonate metal organic compound includes iron acetylacetonate, nickel acetylacetonate, copper acetylacetonate and cobalt acetylacetonate.

2. The method for preparing a hollow framework high entropy oxide oxygen evolution catalyst according to claim 1, wherein: The particle size of the hollow framework high entropy oxide oxygen evolution catalyst is 100-300 nm.

3. The method for preparing a hollow framework high entropy oxide oxygen evolution catalyst according to claim 1, wherein: In step S4, the temperature of the pyrolysis reaction is 300-500° C., and the time is 3-5 hours.

4. The method for preparing a hollow framework high entropy oxide oxygen evolution catalyst according to claim 1, wherein: The heating rate of the pyrolysis reaction is 5-10°C / min.

5. The method for preparing a hollow framework high entropy oxide oxygen evolution catalyst according to claim 1, wherein: Calculated in parts by mass, the organic solution containing dimethylimidazole and acetylacetonate metal organic compound contains 2850 parts by mass of dimethylimidazole, 56 parts by mass of iron acetylacetonate, 41 parts by mass of nickel acetylacetonate, 41 parts by mass of copper acetylacetonate, and 56 parts by mass of cobalt acetylacetonate; The organic solution of zinc nitrate hexahydrate contains 2300 parts by mass of zinc nitrate hexahydrate.

6. The method for preparing a hollow framework high entropy oxide oxygen evolution catalyst according to claim 1, characterized in that: In step S1, the stirring reaction time is 12 to 36 hours.

7. The method for preparing a hollow framework high entropy oxide oxygen evolution catalyst according to claim 1, characterized in that: In step S2, the atmosphere of the carbonization reduction reaction is Ar / H2 atmosphere; The temperature of the carbonization reduction reaction is 800-1000° C., and the time is 2-4 hours.

8. The method for preparing a hollow framework high entropy oxide oxygen evolution catalyst according to claim 1, characterized in that: In step S3, the ruthenium salt is ruthenium chloride, and the mass ratio of ruthenium chloride to the carbonized ZnFeNiCuCo precursor is 4:

10.

9. An oxygen evolution electrode, characterized in that It comprises a substrate and a coating; the coating comprises a hollow framework high entropy oxide oxygen evolution catalyst prepared by the preparation method of a hollow framework high entropy oxide oxygen evolution catalyst according to any one of claims 2-8.

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