Oxygen evolution catalyst, preparation method thereof, electrode and water electrolysis device

Abstract

The invention belongs to the technical field of water electrolysis, and discloses an oxygen evolution catalyst, a preparation method thereof, an electrode and a water electrolysis device. The oxygen evolution catalyst comprises a metal boride and a noble metal oxide, the noble metal oxide is loaded on the metal boride, and the specific surface area of the metal boride is 79m < 2 > / g-90m < 2 > / g. The oxygen evolution catalyst provided by the invention has excellent catalytic activity and stability.

Description

Technical Field

[0001] This application belongs to the field of water electrolysis technology, and particularly relates to an oxygen evolution catalyst, its preparation method, electrodes, and a water electrolysis device. Background Technology

[0002] Water electrolysis mainly consists of two parts: anodic oxygen evolution reaction (OER) and cathodic hydrogen evolution reaction (HER). It has attracted widespread attention due to its cleanliness, efficiency, renewability, and alignment with the trend towards carbon neutrality. Among these technologies, proton exchange membrane (PEM) water electrolyzers are considered the most promising water electrolysis hydrogen production technology compared to solid oxide electrolysis and alkaline electrolyzers because they offer advantages such as high current density, high voltage efficiency, a wide load range, excellent system response, and the ability to produce high-purity gases.

[0003] Currently, in commercially available PEM electrolyzers, the oxygen evolution catalyst mainly uses iridium-based catalysts, represented by IrO2. Iridium, as one of the platinum group metals, is extremely scarce and expensive. To improve resource utilization, using appropriate catalyst supports helps reduce the loading of precious metals and improve catalytic performance.

[0004] However, the strong acid and strong oxidizing working environment of the oxygen evolution reaction at the anode makes it difficult for traditional support materials (such as carbon, metal oxides, etc.) to achieve ideal results, which will affect the catalytic activity and stability of the oxygen evolution catalyst. Summary of the Invention

[0005] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes an oxygen evolution catalyst and its preparation method, electrode, and water electrolysis device, wherein the oxygen evolution catalyst exhibits excellent catalytic activity and stability.

[0006] In a first aspect, this application provides an oxygen evolution catalyst. According to an embodiment of this application, the oxygen evolution catalyst comprises a metal boride and a noble metal oxide, wherein the noble metal oxide is supported on the metal boride, and the specific surface area of ​​the metal boride is 79 m². 2 / g-90m 2 / g.

[0007] According to the oxygen evolution catalyst of the embodiments of this application, by supporting noble metal oxides on metal borides, that is, using metal borides as a support, its 79m 2 / g-90m 2The high specific surface area ( / g) provides numerous anchoring sites for the noble metal oxides, enabling them to distribute more uniformly on the surface of the metal borides and reducing particle agglomeration. The uniformly distributed noble metal oxide particles maintain a smaller particle size, meaning more catalytically active atoms on the surface participate in the oxygen evolution reaction (OER), thus increasing the active sites for the OER and improving its catalytic activity, reducing the required overpotential, and increasing energy conversion efficiency. Furthermore, the uniformly dispersed noble metal oxide particles reduce interparticle contact, minimizing side reactions caused by particle aggregation and improving the stability of the OER catalyst. Therefore, the OER catalyst provided in this application exhibits excellent catalytic activity and stability.

[0008] According to some embodiments of this application, the metal boride has a nanosheet structure with a thickness of 5 nm-10 nm. Thus, the ultrathin nanosheets can provide a higher surface-to-volume ratio, meaning more atoms are located on the surface, increasing the opportunity for contact with reactants and thereby improving the catalytic activity of the oxygen evolution catalyst.

[0009] According to some embodiments of this application, the metal borides include titanium boride. Therefore, the metal borides have a large specific surface area, good electrical conductivity, and high crystallinity, which is beneficial for the dispersion and anchoring of noble metal oxides, thereby increasing catalytic active sites and improving catalytic performance.

[0010] According to some embodiments of this application, the mass percentage of the noble metal oxide is 20%-25% based on the total mass of the oxygen evolution catalyst. Therefore, the amount of noble metal used can be reduced while maintaining catalytic activity, thereby lowering the cost of the oxygen evolution catalyst.

[0011] According to some embodiments of this application, the noble metal oxide includes at least one of iridium dioxide and ruthenium dioxide.

[0012] Secondly, this application provides a method for preparing an oxygen evolution catalyst. According to an embodiment of this application, the preparation method includes mixing a soluble noble metal salt, a nitrate, a metal boride, and a solvent, drying the mixture to obtain a solid precursor, and then heat-treating the solid precursor to obtain the oxygen evolution catalyst. This yields an oxygen evolution catalyst with high catalytic activity and good stability.

[0013] According to some embodiments of this application, the mass ratio of the soluble noble metal salt to the nitrate is 1:(1-20). This is beneficial for obtaining noble metal oxides with small and uniform particle size, which can improve the catalytic activity of the oxygen evolution catalyst.

[0014] According to some embodiments of this application, the soluble noble metal salt includes at least one of chloroiridium acid, iridium trichloride, and iridium acetylacetonate.

[0015] According to some embodiments of this application, the nitrate includes sodium nitrate.

[0016] According to some embodiments of this application, the solvent includes isopropanol.

[0017] According to some embodiments of this application, the step of mixing a soluble noble metal salt, a nitrate, a metal boride, and a solvent, and then drying to obtain a solid precursor includes: mixing and heating the soluble noble metal salt, the nitrate, and the solvent to obtain a mixture A; ultrasonically mixing the metal boride and the solvent to obtain a mixture B; and mixing mixture A and mixture B, followed by drying, to obtain the solid precursor. This yields an oxygen evolution catalyst with high catalytic activity and good stability.

[0018] According to some embodiments of this application, in the mixture A, the mass concentration of the soluble noble metal salt is 2 mg·mL. -1 -10 mg·mL -1 Therefore, it is possible to prepare oxygen evolution catalysts with high active site density, which helps to improve the catalytic activity of oxygen evolution catalysts.

[0019] According to some embodiments of this application, the mixing and heating temperature is 70°C-90°C. This increases the solubility of each component (such as nitrate) in the solvent, contributing to the formation of a homogeneous solution.

[0020] According to some embodiments of this application, the mixing and heating time is 1-5 hours. This ensures that each component has sufficient time to mix evenly, avoiding uneven component distribution due to insufficient mixing.

[0021] According to some embodiments of this application, in mixture B, the mass concentration of the metal boride is 10 mg·mL. -1 -15mg·mL -1 This facilitates the uniform dispersion of noble metal oxides, increases active sites, and thus enhances the catalytic activity of the oxygen evolution catalyst.

[0022] According to some embodiments of this application, the ultrasonic mixing time is 1-2 hours. This refines the metal boride particles, increases particle dispersibility, prevents agglomeration in subsequent processes, and results in a more uniform distribution of metal boride particles.

[0023] According to some embodiments of this application, the ultrasonic power ratio of the ultrasonic mixing is 50%-70%. This allows for uniform dispersion of the metal boride particles in the solvent, preventing particle aggregation and resulting in finer and more uniformly distributed particles.

[0024] According to some embodiments of this application, the heat treatment temperature is 400℃-600℃. This promotes the phase transformation of the soluble noble metal salt to the noble metal oxide, ensuring that the oxygen evolution catalyst achieves the desired crystal structure, thereby facilitating the obtaining of a highly crystallized oxygen evolution catalyst.

[0025] According to some embodiments of this application, the heat treatment time is 1-4 hours. This ensures sufficient time for the chemical reactions during the heat treatment process to fully proceed, achieving the expected phase transformation and structure formation, thereby facilitating the acquisition of an oxygen evolution catalyst with high catalytic activity and good stability.

[0026] According to some embodiments of this application, the heating rate of the heat treatment is 2°C / min to 8°C / min. This reduces the thermal stress generated within the material due to the temperature gradient, preventing cracking or deformation of the oxygen evolution catalyst, thereby facilitating the obtaining of a highly stable oxygen evolution catalyst.

[0027] According to some embodiments of this application, the preparation method of the metal boride includes: mixing a metal oxide, boron powder, and a chloride salt, followed by calcination to obtain the metal boride. This facilitates the preparation of metal borides with a nanosheet structure.

[0028] According to some embodiments of this application, the molar ratio of the boron powder, the chloride salt, and the metal oxide is 10:3:(1-5). This enables the uniform formation of the metal boride, helps ensure the complete reaction of the boron powder, and the appropriate amount of chloride salt promotes the reaction and improves the quality of the product.

[0029] According to some embodiments of this application, the calcination temperature is 1300℃-1400℃. This allows for a more complete chemical reaction between the metal oxide, boron powder, and chloride salt, which is beneficial for forming a metal boride phase with a nanosheet structure.

[0030] According to some embodiments of this application, the Dv50 particle size of the metal oxide is 10 nm-25 nm. This facilitates the preparation of nanosheet-like metal borides, increases the specific surface area of ​​the metal borides, provides more loading sites for the noble metal oxide, promotes uniform dispersion of the noble metal oxide, reduces agglomeration, maintains a smaller particle size, thereby increasing the catalytic active area and improving the catalytic activity of the oxygen evolution catalyst.

[0031] According to some embodiments of this application, the metal oxide includes titanium dioxide.

[0032] According to some embodiments of this application, the chloride salt includes magnesium chloride. This effectively reduces the preparation cost of the oxygen evolution catalyst.

[0033] Thirdly, this application provides an electrode according to an embodiment of the invention, the electrode comprising the oxygen evolution catalyst described above or the oxygen evolution catalyst prepared by the above method, the electrode exhibiting good OER activity and high stability.

[0034] Fourthly, this application provides a water electrolysis device. According to an embodiment of the present invention, the water electrolysis device includes the electrodes described above. Compared with the prior art, the water electrolysis device has better overall performance.

[0035] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0036] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0037] Figure 1 The XRD pattern of titanium boride prepared in Example 1 is shown.

[0038] Figure 2 The BET spectrum of titanium boride prepared in Example 1 is shown;

[0039] Figure 3 SEM images of the titanium boride prepared in Example 1 are shown.

[0040] Figure 4 The image shown is a SEM image of the oxygen evolution catalyst prepared in Example 1;

[0041] Figure 5 The LSV curves of the electrode catalysts of Example 1 are shown in comparison with those of Comparative Examples 1, 2, 3 and 4.

[0042] Figure 6 The BET spectrum of TiO2 in Comparative Example 3 is shown;

[0043] Figure 7 The BET spectrum of TiB2 prepared in Comparative Example 4 is shown. Detailed Implementation

[0044] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0045] In a first aspect, the present invention provides an oxygen evolution catalyst. According to an embodiment of this application, the oxygen evolution catalyst comprises a metal boride and a noble metal oxide, wherein the noble metal oxide is supported on the metal boride, and the specific surface area of ​​the metal boride is 79 m². 2 / g-90m 2 / g.

[0046] As an example, the specific surface area of ​​the metal boride can be 79 m². 2 / g, 83m 2 / g, 85m 2 / g, 87m 2 / g, 90m 2 / g etc.

[0047] It should be noted that precious metals refer to eight metallic elements, including gold, silver, and the platinum group metals (ruthenium, rhodium, palladium, osmium, iridium, and platinum).

[0048] According to the oxygen evolution catalyst of the embodiments of this application, by supporting noble metal oxides on metal borides, that is, using metal borides as a support, its 79m 2 / g-90m 2 The high specific surface area ( / g) provides numerous anchoring sites for the noble metal oxides, enabling them to distribute more uniformly on the surface of the metal borides and reducing particle agglomeration. The uniformly distributed noble metal oxide particles maintain a smaller particle size, meaning more catalytically active atoms on the surface participate in the oxygen evolution reaction (OER), thus increasing the active sites for the OER and improving its catalytic activity, reducing the required overpotential, and increasing energy conversion efficiency. Furthermore, the uniformly dispersed noble metal oxide particles reduce interparticle contact, minimizing side reactions caused by particle aggregation and improving the stability of the OER catalyst. Therefore, the OER catalyst provided in this application exhibits excellent catalytic activity and stability.

[0049] According to some embodiments of this application, the metal boride has a nanosheet structure, and the thickness of the nanosheet is 5 nm-10 nm. For example, the thickness of the nanosheet can be 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, etc. The nanosheet structure increases the specific surface area of ​​the metal boride, providing more anchoring sites for the noble metal oxide, which is beneficial to the uniform distribution of the noble metal oxide, reduces agglomeration, and maintains a small particle size, thereby increasing the catalytic active area and improving the catalytic activity of the oxygen evolution catalyst. Further limiting the thickness of the nanosheet within the above range can obtain ultrathin nanosheets, which can provide a higher surface area to volume ratio, meaning that more catalytically active atoms are located on the surface, increasing the opportunity for contact with reactants, thereby improving the catalytic activity of the oxygen evolution catalyst.

[0050] According to some embodiments of this application, the metal borides include titanium boride. These metal borides have a large specific surface area, good electrical conductivity, and high crystallinity, which is beneficial for the dispersion and anchoring of noble metal oxides, thereby increasing catalytic active sites and improving catalytic performance.

[0051] According to some embodiments of this application, the mass percentage of the noble metal oxide is 20%-25% based on the total mass of the oxygen evolution catalyst. For example, it can be 20%, 21%, 22%, 23%, 24%, 25%, etc. Limiting the mass percentage of the noble metal oxide within the above range can improve the atomic utilization rate of the noble metal in the oxygen evolution catalyst, reduce the amount of noble metal used, and thus reduce the cost of the oxygen evolution catalyst.

[0052] As an example, the noble metal oxide includes at least one of iridium dioxide and ruthenium dioxide.

[0053] In a second aspect, the present invention provides a method for preparing an oxygen evolution catalyst. According to embodiments of this application, the method includes:

[0054] S1. The soluble noble metal salt, nitrate, metal boride and solvent are mixed and dried to obtain a solid precursor.

[0055] In this step, soluble precious metal salts, nitrates and metal borides are mixed, and a solvent is added to form a homogeneous slurry. The mixed slurry is then dried to remove the solvent and form a solid precursor.

[0056] According to some embodiments of this application, the mass ratio of the soluble noble metal salt to the nitrate is 1:(1-20). For example, it can be 1:1, 1:5, 1:10, 1:15, 1:20, etc. By limiting the mass ratio of the soluble noble metal salt to the nitrate within the above range, the low-valence noble metal salt is converted into a high-valence nitrate, and the product is more fully oxidized after subsequent air calcination. This is beneficial for obtaining pure-phase noble metal oxides and can improve the catalytic activity of the oxygen evolution catalyst. According to a specific embodiment of this application, the mass ratio of the soluble iridium salt to the nitrate is 1:10.

[0057] As an example, the soluble noble metal salt includes at least one of a soluble iridium salt and a soluble iridium-ruthenium salt. The soluble iridium salt includes at least one of chloroiridium acid, iridium trichloride, iridium trichloride trihydrate, and iridium acetylacetonate. The nitrate includes sodium nitrate; the solvent includes isopropanol. According to a specific embodiment of this application, the soluble iridium salt is iridium trichloride trihydrate (IrCl3·3H2O).

[0058] According to some embodiments of this application, the preparation method of the metal boride involves mixing a metal oxide, boron powder, and a chloride salt, followed by calcination to obtain the metal boride. During calcination, the chloride salt acts as a flux, lowering the melting point and accelerating the reaction. The metal oxide, as a metal source, reacts with the boron powder to generate the corresponding metal boride. Metal oxides are relatively inexpensive and widely available, effectively reducing the preparation cost of the oxygen evolution catalyst. Furthermore, metal oxides possess good structural plasticity, which is beneficial for obtaining nanosheet-like metal borides, increasing their specific surface area, providing more loading sites for the noble metal oxide, promoting uniform dispersion, reducing agglomeration, maintaining a smaller particle size, thereby increasing the catalytic active area and improving the catalytic activity of the oxygen evolution catalyst.

[0059] According to some embodiments of this application, the molar ratio of the boron powder, the chloride salt, and the metal oxide is 10:3:(1-5). For example, it can be 10:3:1, 10:3:2, 10:3:4, 10:3:5, etc. By limiting the molar ratio of boron powder, chloride salt, and metal oxide within the above range, uniform formation of the metal boride can be achieved, which helps to ensure the full reaction of the boron powder. At the same time, an appropriate amount of chloride salt can promote the reaction and improve the quality of the product.

[0060] According to some embodiments of this application, the calcination temperature is 1300℃-1400℃. For example, it can be 1300℃, 1320℃, 1340℃, 1360℃, 1380℃, 1400℃, etc. By limiting the calcination temperature within the above range, the chemical reaction between the metal oxide, boron powder, and chloride salt is more complete, which is beneficial to the formation of a metal boride phase with a nanosheet structure.

[0061] According to some embodiments of this application, the Dv50 particle size of the metal oxide is 10nm-25nm. For example, it can be 10nm, 14nm, 18nm, 20nm, 23nm, 25nm, etc. By limiting the Dv50 particle size of the metal oxide within the above range, boron atoms can more easily contact the metal oxide and react with oxygen atoms. Furthermore, boron atoms with smaller atomic radii can insert between metal atom layers and grow along the (1-10) crystal plane to form a two-dimensional structure. This facilitates the obtaining of nanosheet-like metal borides, increases the specific surface area of ​​the metal borides, provides more loading sites for the noble metal oxide, promotes uniform dispersion of the noble metal oxide, reduces agglomeration, maintains a smaller particle size, thereby increasing the catalytic active area and improving the catalytic activity of the oxygen evolution catalyst.

[0062] In this invention, Dv50 refers to the particle size corresponding to a cumulative volume distribution percentage of 50%, which is determined using a laser particle size analyzer (e.g., Malvern Master Size 3000) in accordance with standard GB / T19077-2016.

[0063] According to some embodiments of this application, the metal oxide includes titanium dioxide. The aforementioned metal oxide is relatively inexpensive and widely available, effectively reducing the preparation cost of the oxygen evolution catalyst. Furthermore, titanium dioxide and titanium diboride have the same metallic valence state, which is beneficial for obtaining nanosheet-like structures of the boride, increasing the specific surface area of ​​the boride, providing more loading sites for the noble metal oxide, promoting uniform dispersion of the noble metal oxide, reducing agglomeration, maintaining a smaller particle size, thereby increasing the catalytic active area and improving the catalytic activity of the oxygen evolution catalyst.

[0064] According to some embodiments of this application, the chloride salt includes magnesium chloride. Magnesium chloride has good fluidity at high temperatures and can act as a flux to lower the melting point of the reaction system and promote the reaction.

[0065] According to some embodiments of this application, step S10 includes steps S11 and S12:

[0066] S11. Mix and heat a soluble precious metal salt, a nitrate, and a solvent to obtain mixture A.

[0067] In this step, the precious metal salt, nitrate, and solvent are mixed and heated to ensure that all components are completely dissolved and a homogeneous solution is formed.

[0068] According to some embodiments of this application, the mass concentration of the soluble noble metal salt in mixture A is 2 mg / mL to 10 mg / mL. For example, it can be 2 mg / mL, 4 mg / mL, 6 mg / mL, 8 mg / mL, 10 mg / mL, etc. By limiting the mass concentration of the soluble noble metal salt within the above range, uniform dispersion of the noble metal oxide on the metal boride support can be ensured, avoiding aggregation, thereby improving the utilization efficiency of noble metal atoms and preparing an oxygen evolution catalyst with a high active site density, which helps to improve the catalytic activity of the oxygen evolution catalyst. According to a specific embodiment of this application, the mass concentration of the soluble noble metal salt is 3 mg / mL.

[0069] According to some embodiments of this application, the mixing and heating temperature is 70°C-90°C. For example, it can be 70°C, 80°C, 90°C, etc. By limiting the mixing temperature within the above range, the solubility of each component (such as nitrate) in the solvent can be increased, which helps to form a homogeneous solution. According to a specific embodiment of this application, the mixing and heating temperature is 80°C.

[0070] According to some embodiments of this application, the mixing and heating time is 1-5 hours. For example, it can be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, etc. By limiting the mixing time, it is ensured that each component has sufficient time to mix evenly, avoiding uneven component distribution due to insufficient mixing. According to a specific embodiment of this application, the mixing time is 4 hours.

[0071] S12. The metal boride and solvent are ultrasonically mixed to obtain mixture B.

[0072] In this step, the metal borides and solvent are ultrasonically mixed. The cavitation effect of the ultrasound helps to break up the aggregates of metal borides, which can effectively disperse the metal boride particles and avoid agglomeration. This helps to achieve a more uniform loading of noble metal oxides in subsequent catalyst preparation steps.

[0073] According to some embodiments of this application, the mass concentration of the metal boride in mixture B is 10 mg / mL to 15 mg / mL. For example, it can be 10 mg / mL, 11 mg / mL, 12 mg / mL, 13 mg / mL, 14 mg / mL, 15 mg / mL, etc. By limiting the mass concentration of the metal boride within the above range, it is beneficial to achieve uniform dispersion of the noble metal oxide, increase active sites, and thereby improve the catalytic activity of the oxygen evolution catalyst. According to a specific embodiment of this application, the mass concentration of the metal boride is 12 mg / mL.

[0074] According to some embodiments of this application, the ultrasonic mixing time is 1-2 hours. For example, it can be 1 hour, 2 hours, etc. By limiting the ultrasonic mixing time to the above range, the metal boride particles can be refined, the particle dispersibility can be increased, and agglomeration can be avoided in subsequent processes, forming a more uniform distribution of metal boride particles. This provides a large number of contact points for the noble metal oxide, promoting more uniform dispersion of the noble metal oxide on the surface of the metal boride, thereby increasing the active sites for the oxygen evolution reaction. This is beneficial to improving the catalytic activity of the oxygen evolution catalyst for the oxygen evolution reaction. Moreover, the uniformly dispersed noble metal oxide particles reduce the contact between particles, which can reduce side reactions caused by particle aggregation, thereby improving the stability of the oxygen evolution catalyst.

[0075] According to some embodiments of this application, the ultrasonic power ratio of the ultrasonic mixing is 50%-70%. For example, it can be 50%, 60%, 70%, etc. By limiting the ultrasonic power ratio of the ultrasonic mixing within the above range, uniform dispersion of metal boride particles in the solvent can be achieved, avoiding particle aggregation, thereby obtaining finer and more uniformly distributed particles. This provides a large number of contact points for the noble metal oxide, promoting more uniform dispersion of the noble metal oxide on the surface of the metal boride, thereby increasing the active sites for the oxygen evolution reaction. This is beneficial to improving the catalytic activity of the oxygen evolution catalyst for the oxygen evolution reaction. Moreover, the uniformly dispersed noble metal oxide particles reduce the contact between particles, which can reduce side reactions caused by particle aggregation, thereby improving the stability of the oxygen evolution catalyst.

[0076] It should be noted that the ultrasonic power ratio refers to the percentage of the maximum power of the ultrasonic crusher itself when the ultrasonic power is set during ultrasonic crushing.

[0077] S13. Mix mixture A and mixture B, then dry them to obtain the solid precursor.

[0078] In this step, by mixing mixture A and mixture B, specifically, when the solution of mixture A gradually darkens until it turns dark brown, a homogeneous mixture A can be obtained. Then, mixture B is added and mixed evenly, and then dried to obtain a homogeneous solid precursor.

[0079] S2. The solid precursor is subjected to heat treatment to obtain an oxygen evolution catalyst.

[0080] In this step, by heat-treating the solid precursor obtained in step S1, an oxygen evolution catalyst supported on a metal boride can be formed.

[0081] According to some embodiments of this application, the heat treatment temperature is 400℃-600℃, for example, 400℃, 500℃, 600℃, etc. By limiting the heat treatment temperature within the above range, the phase transformation of the soluble noble metal salt to the noble metal oxide is promoted, ensuring that the oxygen evolution catalyst reaches the desired crystal structure, thereby facilitating the obtaining of an oxygen evolution catalyst with high crystallinity. According to a specific embodiment of this application, the heat treatment temperature is 400℃.

[0082] According to some embodiments of this application, the heat treatment time is 1-4 hours. For example, it can be 1 hour, 2 hours, 3 hours, 4 hours, etc. By limiting the heat treatment time within the above range, sufficient time is ensured for the chemical reaction during the heat treatment process to fully proceed, achieving the expected phase transformation and structure formation, thereby facilitating the obtaining of an oxygen evolution catalyst with high catalytic activity and good stability. According to a specific embodiment of this application, the heat treatment time is 1 hour.

[0083] According to some embodiments of this application, the heating rate of the heat treatment is 2°C / min to 8°C / min. For example, it can be 3%, 2°C / min, 4°C / min, 6°C / min, 8°C / min, etc. By limiting the heating rate of the heat treatment within the above range, the thermal stress generated inside the material due to the temperature gradient is reduced, and cracking or deformation of the oxygen evolution catalyst is avoided, thereby facilitating the obtaining of a highly stable oxygen evolution catalyst. According to a specific embodiment of this application, the heating rate of the heat treatment is 5°C / min.

[0084] According to some embodiments of this application, the solid precursor is ground before heat treatment. Grinding the solid precursor significantly increases the specific surface area of ​​each component, providing more contact area for the reactants and helping to improve the rate of the chemical reaction.

[0085] According to embodiments of this application, a pure phase material with a large surface area (specific surface area of ​​85.6 m²) was first synthesized via a molten salt method using low-cost metal oxides, boron powder, and chloride salts as raw materials.2 ·g -1 Highly crystalline, nanosheet-like metal borides were used as supports. A modified Adams melting method was employed to achieve uniform and dense loading of small-sized noble metal oxides. Through innovative combinations of support and loading technologies, a highly active, highly conductive, low-noble-metal-supported catalyst was developed. This supported catalyst also possesses acid stability, high electrical conductivity, and a large specific surface area. Consequently, the resulting oxygen evolution catalyst exhibits excellent catalytic activity and stability.

[0086] In a third aspect of this application, an electrode is provided, according to an embodiment of the invention, comprising the oxygen evolution catalyst described above or an oxygen evolution catalyst prepared by the method described above, the electrode exhibiting good oxygen evolution catalytic activity and high stability.

[0087] In a fourth aspect of this application, a water electrolysis device is proposed. According to an embodiment of the present invention, the water electrolysis device includes the electrodes described above, and compared with the prior art, the water electrolysis device has better overall performance.

[0088] The present disclosure will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be construed as limiting the scope of the disclosure. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0089] Example 1

[0090] 1. Preparation of metal borides:

[0091] (1) Boron powder, anhydrous magnesium chloride and titanium dioxide with a Dv50 of 23 nm are ground thoroughly in an agate mortar in a dry environment until the powder is evenly mixed. The molar ratio of boron powder, anhydrous magnesium chloride and titanium dioxide is 10:3:3.

[0092] (2) Transfer the well-mixed powder to a 30 mL crucible and seal it with the crucible lid. Then, in an argon atmosphere, incubate at 5 °C·min. -1 The temperature was increased to 1350℃ and held for 4 hours. After the reaction was completed and cooled to room temperature, the product was dispersed in 40 mL of deionized water and stirred in an oil bath at 100℃ to remove magnesium chloride and boron trioxide. The product was then washed with hot water and centrifuged 5 times. It was then vacuum dried at 60℃ for 12 hours to obtain titanium boride (TiB2).

[0093] 2. Preparation of oxygen evolution catalyst:

[0094] (1) IrCl3·3H2O and sodium nitrate were thoroughly mixed in isopropanol to obtain mixture A. In mixture A, the content of IrCl3·3H2O was 3 mg / mL, and the mass ratio of IrCl3·3H2O to NaNO3 was 1:10. The self-made titanium boride was dispersed in isopropanol and sonicated for 1 h with an ultrasonic power ratio of 60% to make the titanium boride uniformly dispersed in isopropanol to obtain mixture B. In mixture B, the content of titanium boride was 12 mg / mL. Mixture A was placed in an oil bath and stirred at 80°C. When the color of mixture A gradually deepened until it turned dark brown, mixture B was added. The total heating and stirring time was 4 h. The obtained product was dried in a drying oven at 60°C to obtain a solid precursor.

[0095] (2) The obtained dry solid precursor was ground in an agate mortar for 0.5 h, and then the ground powder was loaded into a quartz boat and placed in a tube furnace and calcined in air at 400 °C for 1 h (heating rate 5 °C / min) to obtain the oxygen evolution catalyst of IrO2 / TiB2.

[0096] 3. Electrode Preparation: A turbid solution of oxygen evolution catalyst (OEC) was prepared, consisting of 0.0377 mg / μL isopropanol and ultrapure water, with a volume ratio of isopropanol:ultrapure water:Nafion (5 wt.%) of 55:23:1. The solution was sonicated for 1 hour until homogeneous. 3 μL of the solution was pipetted onto a glassy carbon electrode. After evaporation at room temperature, a working electrode with an OEC catalyst layer was obtained, with an OEC catalyst loading of 0.9 mg·cm³. -2 The IrO2 loading was 0.21 mg·cm³. -2 .

[0097] Example 16

[0098] Commercial TiB2 was used to replace the TiB2 prepared in Example 1, and the rest remained the same as in Example 1. The commercial TiB2 was sourced from Shanghai Adamas Reagent Co., Ltd.

[0099] Examples 2-16 prepared oxygen evolution catalysts, which were the same as those in Example 1 except for the different experimental parameters (see Table 1).

[0100] Comparative Example 1

[0101] Instead of using metal boride as a support, commercial iridium dioxide was directly selected as the oxygen evolution catalyst, with the iridium dioxide sourced from solar hydrogen energy.

[0102] Comparative Example 2

[0103] Instead of using metal boride as a support, commercial iridium dioxide was directly selected as the oxygen evolution catalyst, with the iridium dioxide sourced from solar hydrogen energy.

[0104] Comparative Example 3

[0105] TiO2 was used to replace the TiB2 prepared in Example 1. The specific surface area of ​​TiO2 was 78.9 m². 2 ·g -1 The rest remains the same as in Example 1.

[0106] The experimental parameters for preparing oxygen evolution catalysts in Examples 1-16 and Comparative Examples 1-3 of this application are shown in Table 1.

[0107] Table 1

[0108]

[0109] Testing and Analysis

[0110] Under the same conditions, the electrodes prepared in Examples 1-13 and Comparative Examples 1-4 were subjected to electrochemical performance and stability tests. The specific test methods are as follows:

[0111] Electrochemical performance testing: Electrochemical performance testing was conducted in a 0.5M H₂SO₄ solution at a temperature of 25℃. A three-electrode system was used, and the testing was performed on a CHI-760 electrochemical workstation. The counter electrode was a graphite rod electrode, the reference electrode was a saturated calomel electrode, and the working electrode was a 4mm diameter glassy carbon electrode with an electrode area of ​​0.1256 cm². 2 Under constant temperature of 25℃, the catalyst-coated working electrode was immersed in the electrolyte at a rate of 500 mV·s. -1 The electrode was activated by performing 50 cyclic voltammetric scans at a certain scan rate. Then, the disk electrode rotation speed was adjusted to 1600 rpm, and a 5 mV·s scan was performed. -1 The scan rate proceeded from low potential to high potential, with each sample tested three times. The test voltage range was 1.1V–1.7V (vs RHE). The RHE electrode is a reversible hydrogen electrode, a common electrode in electrochemical testing. Readouts were taken at 10 mA·cm⁻¹. -2 The activity of the catalyst in the oxygen evolution reaction (OER) is specifically evaluated by measuring the voltage value at the current density.

[0112] Stability testing: The test was conducted in a 0.5M H₂SO₄ solution at 25°C. The disk electrode rotation speed was adjusted to 400 rpm, and 500 cyclic voltammetric scans were performed at a potential of 0.05V–1.2V (vs RHE). Afterward, the electrolyte was replaced, and the above electrochemical performance tests were performed again.

[0113] from Figure 1 The XRD pattern shows that the prepared titanium boride has good crystallinity and is a pure phase titanium boride.

[0114] Figure 2 and Figure 7 The BET spectrum shows that the titanium boride support prepared at 1350℃ has a large specific surface area. From these results, it can be inferred that the prepared titanium boride is an ideal oxygen evolution catalyst support, which can further achieve uniform and dense loading of small-sized IrO2.

[0115] Figure 3 The SEM images show that the titanium boride support prepared at 1350℃ exhibits a uniform morphology of ultrathin two-dimensional nanosheets with a thickness of approximately 5nm to 10nm.

[0116] from Figure 4 The SEM images show that iridium dioxide nanoparticles are uniformly loaded on the TiB2 support surface.

[0117] from Figure 5 The LSV performance graph shows that the prepared IrO2 / TiB2 still exhibits high OER activity even with low iridium loading, at a current density of 10 mA·cm⁻¹. -2 At that time, the oxygen evolution overpotential was 229mV.

[0118] Figure 2 and Figure 6 The BET spectrum shows that TiB2 prepared by borizing TiO2 increases the specific surface area of ​​the support.

[0119] The test results are shown in Table 2.

[0120] Table 2

[0121]

[0122]

[0123] Combining Tables 1 and 2, it can be seen that, compared with Comparative Examples 1-4, the oxygen evolution catalysts of Examples 1-13 exhibit superior catalytic performance and stability. This is due to the large specific surface area of ​​the prepared two-dimensional titanium boride nanosheets, which allows iridium dioxide to be uniformly loaded on the surface, avoiding aggregation, thereby improving the utilization efficiency of noble metal atoms and the durability of the catalyst.

[0124] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0125] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0126] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. An oxygen evolution catalyst, characterized in that, include: Metal borides, wherein the specific surface area of ​​the metal borides is 79 m² 2 / g-90m 2 / g; A noble metal oxide, wherein the noble metal oxide is supported on the metal boride.

2. The oxygen evolution catalyst according to claim 1, characterized in that, The metal boride has a nanosheet structure, the thickness of which is 5 nm-10 nm; and / or, The metal borides include titanium boride.

3. The oxygen evolution catalyst according to claim 1 or 2, characterized in that, Based on the total mass of the oxygen evolution catalyst, the mass percentage of the noble metal oxide is 20%-25%; and / or, The noble metal oxide includes at least one of iridium dioxide and ruthenium dioxide.

4. A method for preparing the oxygen evolution catalyst according to any one of claims 1-3, characterized in that, include: A soluble noble metal salt, nitrate, metal boride, and solvent are mixed and dried to obtain a solid precursor. The solid precursor was subjected to heat treatment to obtain an oxygen evolution catalyst.

5. The method according to claim 4, characterized in that, The mass ratio of the soluble noble metal salt to the nitrate is 1:(1-20); and / or, The soluble noble metal salt includes at least one of chloroiridium acid, iridium trichloride, and iridium acetylacetonate; and / or, The nitrate includes sodium nitrate; and / or, The solvent includes isopropanol.

6. The method according to claim 4 or 5, characterized in that, The steps of mixing a soluble noble metal salt, a nitrate, a metal boride, and a solvent, and then drying them to obtain a solid precursor include: A soluble noble metal salt, nitrate, and solvent are mixed and heated to obtain mixture A; The metal boride and solvent were ultrasonically mixed to obtain mixture B; Mixture A and mixture B are mixed and then dried to obtain the solid precursor.

7. The method according to claim 6, characterized in that, In the mixture A, the mass concentration of the soluble noble metal salt is 2 mg / mL-10 mg / mL; and / or, The temperature of the mixed heating is 70℃-90℃; and / or, The heating time for the mixture is 1-5 hours.

8. The method according to claim 6, characterized in that, In mixture B, the mass concentration of the metal boride is 10 mg / mL to 15 mg / mL; and / or, The ultrasonic mixing time is 1-2 hours; and / or, The ultrasonic power ratio of the ultrasonic mixture is 50%-70%.

9. The method according to claim 4 or 5, characterized in that, The heat treatment temperature is 400℃-600℃; and / or, The heat treatment time is 1 hour to 4 hours; and / or, The heating rate of the heat treatment is 2℃ / min-8℃ / min.

10. The method according to any one of claims 4-9, characterized in that, The method for preparing the metal boride includes: The metal boride is obtained by mixing metal oxide, boron powder and chloride salt and then calcining.

11. The method according to claim 10, characterized in that, The molar ratio of the boron powder, the chloride salt, and the metal oxide is 10:3:(1-5); and / or, The calcination temperature is 1300℃-1400℃; and / or, The Dv50 particle size of the metal oxide is 10nm-25nm; and / or, The metal oxide includes titanium dioxide; and / or, The chloride salt includes magnesium chloride.

12. An electrode, characterized in that, The electrode comprises the oxygen evolution catalyst according to any one of claims 1-3 or the oxygen evolution catalyst prepared by any one of claims 4-11.

13. A water electrolysis device, characterized in that, The water electrolysis device includes the electrode as described in claim 12.

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