Electrolysis water device, catalyst, and preparation method and application thereof

Abstract

The present application relates to the technical field of catalysts, and relates to an electrolytic water device, a catalyst, and a preparation method and application thereof. The catalyst comprises a core layer structure and a shell layer structure arranged on the surface of the core layer structure, and the shell layer structure is provided with active substances on the pores and / or surface thereof; the core layer structure comprises rare earth oxides, and the shell layer structure comprises conductive porous materials; and the active substances comprise at least one of noble metal atoms, noble metal elements, and noble metal alloys. The present application can improve the service life of the electrolytic water device in the whole life cycle.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a water electrolysis device, a catalyst, its preparation method, and its application. Background Technology

[0002] A catalyst is a substance that alters the rate of a chemical reaction without changing its own mass or chemical properties before and after the reaction. Solid catalysts are widely used in various heterogeneous catalytic reactions. They consist of a support and an active component. The support in a solid catalyst plays a role in supporting, dispersing, and diluting the active component, thereby improving the catalyst's strength.

[0003] In chemical reactions, the stability of a catalyst can affect its catalytic performance. Summary of the Invention

[0004] The main objective of this invention is to provide a water electrolysis device that improves the stability of the catalyst, thereby increasing the service life of the water electrolysis device.

[0005] To achieve the above objectives, the present invention proposes a water electrolysis device, comprising a membrane electrode, wherein the membrane electrode comprises an ion exchange membrane and a catalyst layer disposed on the ion exchange membrane, the catalyst layer comprises a catalyst, the catalyst comprises a core layer structure and a shell layer structure disposed on the surface of the core layer structure, and the pores and / or surface of the shell layer structure are provided with active substances;

[0006] The core structure comprises rare earth oxides, and the shell structure comprises conductive porous materials.

[0007] The active substance includes at least one of noble metal atoms, noble metal elements, and noble metal alloys.

[0008] Rare earth oxides possess good stability, and using them as the core-shell structure to support the outer shell structure can improve the stability of the catalyst. Simultaneously, the outer shell structure includes conductive porous materials, with active substances located in the pores and / or on the surface of the shell structure. These active substances include materials that catalyze the oxygen evolution reaction in water electrolysis. The conductive porous materials enhance the conductivity of the catalyst, thereby improving its catalytic performance. The catalyst of this application exhibits good stability and catalytic activity. Enhanced stability can extend the operating time of the water electrolysis device, thus improving its overall lifespan.

[0009] Optionally, the conductive porous material includes nitrogen-doped carbon material;

[0010] And / or, the rare earth oxides include at least one of CeO2, La2O3, Ce2O3, Nd2O3, Eu2O3, and Gd2O3;

[0011] And / or, the noble metal atom, the noble metal element, or the noble metal alloy includes at least one of Ir, Ru, Pd, and Pt.

[0012] In theory, conductive porous materials can include nickel foam, carbon materials, porous Pt layers, etc.

[0013] In one embodiment, the conductive porous material includes nitrogen-doped carbon material, that is, the nitrogen element contained in the carbon material can coordinate with the active material, regulate the electronic structure of the active site of the active material, thereby optimizing the catalytic performance and improving the stability of the active material dispersed in the shell structure, thereby improving the stability of the catalyst.

[0014] In one embodiment, the rare earth oxide includes at least one of CeO2, La2O3, Ce2O3, Nd2O3, Eu2O3, and Gd2O3. That is, the rare earth oxide may include any one of these, or multiple of them simultaneously. In particular, CeO2 has excellent oxygen storage and release capacity, acid and alkali corrosion resistance, and high voltage characteristics. In one embodiment, the rare earth oxide includes at least CeO2. In one embodiment, the rare earth oxide includes CeO2 in an acidic electrolyte environment, and at least one of La2O3, Ce2O3, Nd2O3, Eu2O3, and Gd2O3 in an alkaline electrolyte environment.

[0015] In one embodiment, the noble metal element in the noble metal atom, noble metal element, or noble metal alloy includes at least one of Ir, Ru, Pd, and Pt.

[0016] Optionally, the ID / IG ratio of the nitrogen-doped carbon material is from 0.95 to 1.25;

[0017] And / or, the nitrogen doping mass in the nitrogen-doped carbon material is 10% to 15%.

[0018] In one embodiment, ID / IG refers to the Raman spectroscopy used to measure the nitrogen-doped carbon material at a wavenumber of 1345 cm⁻¹. -1 The disordered D-band intensity on the left and right and 1590cm -1 The ratio of the graphitized G-band intensity on the left and right sides indicates the degree of graphitization; the lower the ratio, the higher the degree of graphitization.

[0019] Graphitization degree is an indicator that measures the extent to which carbon materials, through structural rearrangement, approach perfect graphite in crystal form. It reflects the degree of perfection of graphite crystals in a material; the higher the degree of graphitization, the better the electrical conductivity of the material.

[0020] The nitrogen-doped carbon material of this application has a high degree of graphitization, indicating that it has good electrical conductivity, that is, the conductive porous material has good electrical conductivity. The conductivity of the catalyst can be improved by using conductive porous materials, thereby improving the catalytic performance.

[0021] In one embodiment, the doping quality of nitrogen in nitrogen-doped carbon materials can be tested by elemental analysis (e.g., energy dispersive spectroscopy). N can coordinate with active substances, thereby controlling the active sites and stability of active substances. The higher the N content, the more sites there are for coordination with active substances, which facilitates improving the loading and coordination stability of active substances.

[0022] Optionally, the catalyst has a specific surface area of ​​550 m². 2 / g to 650m 2 / g;

[0023] And / or, the particle size Dv50 of the catalyst is from 5 nm to 25 nm;

[0024] And / or, the core layer structure is a porous structure, and the particle size Dv50 of the core layer structure is 5 nm to 20 nm;

[0025] And / or, the specific surface area of ​​the core layer structure is 60 m². 2 / g to 80m 2 / g;

[0026] And / or, the thickness of the conductive porous material is 1 nm to 5 nm;

[0027] And / or, the mass percentage of the active material in the catalyst is 1.2% to 16%.

[0028] In one embodiment, the specific surface area of ​​the catalyst meets the above-mentioned range, and the nitrogen-doped carbon material has a porous structure containing micropores and mesopores, which effectively increases the specific surface area of ​​the material. The increase in specific surface area can effectively improve the loadable area of ​​the active material and the contactability between the electrolyte and the active material, which is beneficial to improving the utilization rate of the active material.

[0029] In one embodiment, the particle size of the catalyst meets the above-mentioned range. Small-sized catalyst particles facilitate the transport of reactants and products, thereby increasing the reaction rate.

[0030] In one embodiment, the core layer structure is a porous structure with a particle size that meets the above-mentioned range. The core layer structure includes CeO2, which has the function of storing and releasing oxygen. The internal pores of the CeO2 structure are micropores and mesopores with a particle size in the nanometer range, which helps to increase the specific surface area of ​​the core layer structure and thus improve the oxygen storage and release capacity.

[0031] In one embodiment, the specific surface area of ​​the core layer structure meets the above-mentioned range, and the core layer structure includes CeO2. CeO2 has the function of storing and releasing oxygen, and the specific surface area is increased, thereby improving the oxygen storage and release capacity.

[0032] In one embodiment, the thickness of the conductive porous material within the aforementioned range helps improve conductivity and mass-charge transport capability during the catalytic process. It is understood that the thickness of the conductive porous material affects conductivity and mass-charge transport capability during the catalytic process; the thickness of the conductive porous material should not be too thick, otherwise it will increase mass-charge transport resistance.

[0033] In one embodiment, the mass percentage of the active material in the catalyst meets the above-mentioned range, and the active material in the catalyst can still maintain good catalytic activity at the above-mentioned mass percentage. It is understood that, in one embodiment, based on nitrogen-doped carbon material as a conductive porous material, the active material, through coordination with N, helps to stably locate in the pores and / or surface of the conductive porous material, and the catalyst can still maintain good catalytic performance during long-term operation.

[0034] Optionally, the active material includes noble metal atoms, and the mass percentage of the active material in the catalyst is 1.2% to 3%.

[0035] Alternatively, the active material may be present in the form of sub-nano clusters, and the mass percentage of the active material in the catalyst may be 3% to 5%.

[0036] Alternatively, the active material may be present in the form of nanoparticles, and the mass percentage of the active material in the catalyst may be 6% to 12%.

[0037] In one embodiment, the active material includes noble metal atoms, and the mass percentage of the active material in the catalyst is 1.2% to 3%. Noble metal atoms have higher utilization of active sites, lower loading, and better catalytic performance.

[0038] In one embodiment, the active material comprises sub-nano clusters, and the mass percentage of the active material in the catalyst is 3% to 5%.

[0039] In one embodiment, the active material comprises nanoparticles, and the mass percentage of the active material in the catalyst is 6% to 12%.

[0040] In one embodiment, the ion exchange membrane includes anion exchange membrane or cation exchange membrane.

[0041] Optionally, this application also provides a catalyst, the catalyst comprising a core layer structure and a shell layer structure disposed on the surface of the core layer structure, wherein the pores and / or surface of the shell layer structure are provided with active substances;

[0042] The core structure comprises rare earth oxides, and the shell structure comprises conductive porous materials.

[0043] The active substance includes at least one of noble metal atoms, noble metal elements, and noble metal alloys.

[0044] Optionally, the conductive porous material includes nitrogen-doped carbon material;

[0045] And / or, the rare earth oxides include at least one of CeO2, La2O3, Ce2O3, Nd2O3, Eu2O3, and Gd2O3;

[0046] And / or, the noble metal atom, the noble metal element, or the noble metal alloy includes at least one of Ir, Ru, Pd, and Pt.

[0047] Optionally, the nitrogen-doped carbon material I D / I G The value ranges from 0.95 to 1.25.

[0048] And / or, the nitrogen doping mass in the nitrogen-doped carbon material is 10% to 15%.

[0049] Optionally, the catalyst has a specific surface area of ​​550 m². 2 / g to 650m 2 / g;

[0050] And / or, the particle size Dv50 of the catalyst is from 5 nm to 25 nm;

[0051] And / or, the core layer structure is a porous structure, and the particle size of the core layer structure is 5 nm to 20 nm;

[0052] And / or, the specific surface area of ​​the core layer structure is 60 m². 2 / g to 80m 2 / g;

[0053] And / or, the thickness of the conductive porous material is 1 nm to 5 nm;

[0054] And / or, the mass percentage of the active material in the catalyst is 1.2% to 16%.

[0055] Optionally, this application also provides a method for preparing a catalyst, comprising:

[0056] Rare earth oxides, metal sources, and organic ligands are dispersed in a solvent, stirred, and dried to obtain a catalyst precursor, wherein the metal source includes an active material source.

[0057] The catalyst precursor was calcined in an inert atmosphere to obtain the catalyst.

[0058] In the catalyst preparation process, rare earth oxides can be prepared first. The rare earth oxides, metal sources, and organic ligands are dispersed in a solvent, stirred, and dried to generate metal-organic framework compounds on the surface of the rare earth oxides. Active substances are then introduced into the metal-organic framework compounds to obtain the catalyst precursor.

[0059] The catalyst precursor is calcined in an inert atmosphere, so that the metal-organic framework compound is pyrolyzed at high temperature to become a conductive porous carbon material, and the active material is located on the surface and / or pores of the conductive porous carbon material, thus obtaining the catalyst.

[0060] This application describes the in-situ growth of metal-organic framework compounds on the surface of rare earth oxides. The active material source serves as a metal source and acts as a metal node in the metal-organic framework compound, which helps to improve the dispersion uniformity of the active material in the metal-organic framework compound, increase the utilization rate of the active material, and reduce the loading of the active material.

[0061] Optionally, the metal source may further include a source of inactive substances;

[0062] The molar ratio of the metal in the inactive material source to the metal in the active material source is greater than 4 and less than 16; or, the molar ratio of the metal in the inactive material source to the metal in the active material source is greater than or equal to 2 and less than or equal to 4; or, the molar ratio of the metal in the inactive material source to the metal in the active material source is greater than 0.1 and less than 2.

[0063] In one embodiment, the metal source also includes an inactive material source. The metal element in the inactive material source can be a metal element without catalytic activity. The metal in the inactive material source also serves as a metal node in the metal-organic framework compound. The introduction of the inactive material can reduce the amount of active material used, while improving the uniformity of the distribution of the active material and regulating the catalytic performance. It is understood that, for example, if the active element includes Ir and the inactive element includes Zn, and the metal nodes in the metal-organic framework compound include Zn and Ir, nodes with Zn and Ir cross-distribution can be formed. Zn acts as a separator for Ir sites, preventing the aggregation of Ir sites and facilitating the regulation of the size of Ir active sites. Pure Ir without the Zn spacing cannot regulate the size of single atoms, sub-nanometer clusters, and nanoparticles.

[0064] In one embodiment, the molar ratio of the metal in the inactive material source to the metal in the active material source is greater than 4 and less than 16; this helps to control the size of the active material to the single-atom level, resulting in higher utilization of active sites, lower loading, and better catalytic performance of the single-atom catalyst.

[0065] In one embodiment, the molar ratio of the metal in the inactive material source to the metal in the active material source is greater than or equal to 2 and less than or equal to 4; the size of the active material can be controlled to form sub-nanometer clusters.

[0066] In one embodiment, the molar ratio of the metal in the inactive material source to the metal in the active material source is greater than 0.1 and less than 2; the size of the active material can be controlled to form a nanoscale.

[0067] Optionally, the organic ligand includes organic compounds containing carbon and nitrogen.

[0068] And / or, the molar ratio of the organic ligand to the metal source is 2:1 to 16:1;

[0069] And / or, each 100 mg of the rare earth oxide corresponds to 2 mmol to 160 mmol of the organic ligand and 1 mmol to 10 mmol of the metal source;

[0070] And / or, the rare earth oxides include at least one of CeO2, La2O3, Ce2O3, Nd2O3, Eu2O3, and Gd2O3;

[0071] And / or, the metal element in the inactive material source includes at least one of Zn, Co, Ni, Cu, Mn, Ti, Ta, and Nb;

[0072] And / or, the metal element in the active material source includes at least one of Ir, Ru, Pd, and Pt;

[0073] And / or, the organic ligand includes at least one of dimethylimidazolium, pyridine, pyrrole, and phthalocyanine;

[0074] And / or, in the step of calcining the catalyst precursor in an inert atmosphere, the calcination temperature is 800°C to 900°C.

[0075] In one embodiment, the organic ligand includes organic compounds containing carbon and nitrogen. Thus, during the formation of the metal-organic framework compound, the metal ion coordinates with nitrogen (N), which is an in-situ coordination of metal and nitrogen. Even after calcination and carbonization, the metal ion can still coordinate with nitrogen, which helps to regulate the active sites of the active substance and enhance its stability. Carbonization refers to the pyrolysis of organic matter at high temperatures, causing the crystal structure to collapse and forming corresponding nitrogen-containing carbonized derivatives.

[0076] In one embodiment, the molar ratio of the organic ligand to the metal source is between 2:1 and 16:1. It is understood that a suitable molar ratio of organic ligand to metal source facilitates the preparation of metal-organic framework compounds.

[0077] In one embodiment, each 100 mg of rare earth oxide corresponds to 2 mmol to 160 mmol of organic ligand and 1 mmol to 10 mmol of metal source. This helps to prepare a conductive porous material with a suitable thickness on the surface of the rare earth oxide, which helps to improve conductivity and mass-charge transport capabilities during the catalytic process. It is understood that the ratio of the metal-organic framework compound feedstock to the mass of the rare earth oxide affects the thickness of the metal-organic framework compound formed on the surface of the rare earth oxide, and thus affects the thickness of the conductive porous material after carbonization (the metal-organic framework compound becomes a conductive porous material after carbonization), thereby affecting conductivity.

[0078] In one embodiment, the rare earth oxide includes at least one of CeO2, La2O3, Ce2O3, Nd2O3, Eu2O3, and Gd2O3.

[0079] In one embodiment, the metal element in the inactive material source includes at least one of Zn, Co, Ni, Cu, Mn, Ti, Ta, and Nb.

[0080] In one embodiment, the metal element in the active material source includes at least one of Ir, Ru, Pd, and Pt.

[0081] In one embodiment, the organic ligand includes at least one of dimethylimidazole, pyridine, pyrrole, and phthalocyanine.

[0082] In one embodiment, the step of calcining the catalyst precursor in an inert atmosphere is carried out at a temperature of 800°C to 900°C. During the high-temperature pyrolysis process, the rare earth oxides are stable, and the organic ligands in the metal-organic framework compound undergo carbonization and decomposition to form a conductive porous material.

[0083] It is also understandable that the inactive metal nodes (such as Zn) in metal-organic framework compounds will volatilize because the calcination temperature reaches the boiling point of the inactive material but not the boiling point of the active material (such as Ir). Therefore, the active material is retained and coordinated by N in the organic ligand.

[0084] Simultaneously, the coordination number of N can be controlled by adjusting the calcination temperature. Adjusting the coordination number of N at the aforementioned temperatures allows for uniform loading of active materials. For example, in-situ growth of metal-organic framework compounds on a CeO2 substrate followed by high-temperature pyrolysis produces a carbon-nitrogen substrate with excellent conductivity, enhancing the catalyst's conductivity. Furthermore, the coordination of nitrogen-containing ligands in organometallic covalent compounds ensures uniform distribution of Ir sites, improving the utilization rate of active sites and reducing the Ir loading.

[0085] Furthermore, the inactive substances (such as Zn) in the metal-organic framework volatilize during the high-temperature carbonization process, which enhances the porous characteristics of the conductive porous material while ensuring the uniform distribution of Ir sites. This is beneficial for increasing the specific surface area, which can effectively improve the load-bearing area of ​​the active material and the contactability between the electrolyte and the active material, thereby improving the utilization rate of the active material.

[0086] The values ​​in the range of 800℃ to 900℃ include the minimum and maximum values ​​of this range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, as well as 800℃, 850℃, 900℃, etc., and the range values ​​between any two of the above point values.

[0087] Optionally, this application also provides an anode catalyst for water electrolysis, wherein the anode catalyst for water electrolysis comprises the catalyst described above, or the anode catalyst for water electrolysis comprises a catalyst prepared by the method described above.

[0088] Optionally, this application also provides an application of the water electrolysis apparatus as described above.

[0089] The water electrolysis device provided in this application includes a membrane electrode, which comprises an ion exchange membrane and a catalyst layer disposed on the ion exchange membrane. The catalyst layer includes a catalyst, which comprises a core structure and a shell structure disposed on the surface of the core structure. The pores and / or surface of the shell structure are provided with active material. The core structure includes rare earth oxides, and the shell structure includes conductive porous materials. The active material includes at least one of noble metal atoms, noble metal elements, and noble metal alloys. Rare earth oxides have good stability, and using them as a support for the shell structure of the core structure can improve the stability of the catalyst. At the same time, the shell structure includes conductive porous materials, and the active material is located in the pores and / or surface of the shell structure. The active material includes substances that catalyze the oxygen evolution reaction in water electrolysis. The conductive porous materials can improve the conductivity of the catalyst, thereby improving the catalytic performance. The catalyst of this application has good stability and catalytic activity. Enhanced stability can increase the operating time of the water electrolysis device, thereby increasing the service life of the water electrolysis device. Attached Figure Description

[0090] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0091] Figure 1 This is a schematic diagram of the structure of the catalyst in Example 1 of this application;

[0092] Figure 2 This is a transmission electron microscope (TEM) image (TED) of the catalyst in Example 1 of this application;

[0093] Figure 3 This is the X-ray diffraction (XRD) pattern of the catalyst in Example 1 of this application;

[0094] Figure 4 This is a high-angle ring dark-field scanning transmission electron microscope (HAADF-STEM) image of the catalyst in Example 1 of this application;

[0095] Figure 5 This is the energy dispersive spectroscopy (EDS) spectrum of nitrogen in the catalyst of Example 1 of this application;

[0096] Figure 6 This is the energy dispersive spectroscopy (EDS) spectrum of Ce element in the catalyst of Example 1 of this application;

[0097] Figure 7 This is the energy dispersive spectroscopy (EDS) spectrum of Ir element in the catalyst of Example 1 of this application;

[0098] Figure 8 These are linear voltammetric scan curves of Embodiment 1 of this application and Comparative Examples 1 and 2.

[0099] Figure 9 This is a constant potential timing current curve diagram of Embodiment 1 of this application;

[0100] Figure 10 This is a schematic diagram of the process for preparing the catalyst in this application.

[0101] Explanation of icon numbers:

[0102] label name label name 100 catalyst 20 shell structure 10 Core layer structure 30 Active substances

[0103] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0104] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0105] The catalyst, its preparation method, and its application are disclosed in detail below with appropriate reference to the accompanying drawings. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of essentially the same structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0106] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0107] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0108] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0109] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0110] Some chemical reactions are subject to harsh conditions, and the stability of catalysts can be affected when subjected to adverse reaction environments, which in turn affects the performance of water electrolysis devices.

[0111] To improve the performance of water electrolysis devices, this application proposes a water electrolysis device, including a membrane electrode, which includes an ion exchange membrane and a catalyst layer disposed on the ion exchange membrane. The catalyst layer includes a catalyst, which includes a core structure and a shell structure disposed on the surface of the core structure. The pores and / or surface of the shell structure are provided with active material. The core structure includes rare earth oxides, and the shell structure includes conductive porous materials. The active material includes at least one of noble metal atoms, noble metal elements, and noble metal alloys.

[0112] Core layer structure and shell structure located on the surface of core layer structure, such as Figure 1 As shown, in the core-shell structure of catalyst 100, the shell structure 20 is located on the surface of the core structure 10, and the active material 30 is distributed in the shell structure 20.

[0113] Rare earth oxides are compounds formed by rare earth elements and oxygen.

[0114] Conductive porous materials refer to a class of conductive materials with porous structures.

[0115] Active substances are substances that possess catalytic activity.

[0116] Metal atoms refer to single metallic atoms that have not formed a metallic elemental phase and do not have metal-metal bonds. Instead, they are stabilized on the matrix through coordination with the matrix (shell structure). Metallic elements are generally pure substances in which metal atoms form metal-metal bonds and are arranged in a specific packing pattern. Metal alloys are generally materials in which different metal atoms form metal-metal bonds and are arranged in a specific packing pattern.

[0117] Rare earth oxides possess good stability, and using them as the core-shell structure to support the outer shell structure can improve the stability of the catalyst. Simultaneously, the outer shell structure includes conductive porous materials, with active substances located in the pores and / or on the surface of the shell structure. These active substances include materials that catalyze the oxygen evolution reaction in water electrolysis. The conductive porous materials enhance the conductivity of the catalyst, thereby improving its catalytic performance. The catalyst of this application exhibits good stability and catalytic activity. Enhanced stability can extend the operating time of the water electrolysis device, thus improving its overall lifespan.

[0118] In one embodiment, the conductive porous material comprises a nitrogen-doped carbon material.

[0119] In theory, conductive porous materials can include nickel foam, carbon materials, porous Pt layers, etc. Conductive porous materials include nitrogen-doped carbon materials, meaning that the nitrogen element contained in the carbon material can coordinate with the active material, regulate the electronic structure of the active site of the active material, thereby optimizing the catalytic performance and improving the stability of the active material dispersed in the shell structure, thus improving the stability of the catalyst.

[0120] In one embodiment, the rare earth oxide includes at least one of CeO2, La2O3, Ce2O3, Nd2O3, Eu2O3, and Gd2O3. That is, the rare earth oxide may include any one of them, or may include multiple ones simultaneously. In particular, CeO2 has excellent oxygen storage and release capacity, acid and alkali corrosion resistance, and high voltage characteristics. In one embodiment, the rare earth oxide includes at least CeO2.

[0121] For example, CeO2 has a fluorite structure, in which Ce has a strong ability to change valence (CeO2). 3+ / Ce 4+ CeO2 can generate and release lattice oxygen defects, thus possessing a strong ability to store and release oxygen. It is understandable that CeO2 contains both Ce and Ce. 3+ and Ce 4+ In an oxygen-deficient environment, Ce in CeO2 4+ Can be reduced to Ce 3+ This is accompanied by the release of O2 and the formation of oxygen vacancies; in an oxygen-rich environment, Ce... 3+ It can be oxidized to Ce 4+ This is accompanied by the absorption of O2 and the disappearance of oxygen vacancies.

[0122] Oxygen produced by the catalysis of active substances can be transferred in a timely manner through the interface between CeO2, the shell structure and the active substance, with the help of CeO2's oxygen storage and release capacity. This reduces the accumulation of oxygen bubbles, thereby weakening the impact of bubble pressure on the active substance and helping to improve the stability of the active substance dispersed in the shell structure, thus improving the stability of the catalyst.

[0123] In other words, rare earth oxide CeO2 has high oxygen storage capacity and electron transfer capacity. As a catalyst, the core structure can act as an oxygen "buffer", timely transporting the generated oxygen, improving the oxygen transport capacity of the catalyst, and promoting the forward reaction.

[0124] In one embodiment, the noble metal element in the noble metal atom, noble metal element, or noble metal alloy includes at least one of Ir, Ru, Pd, and Pt.

[0125] In one embodiment, the ID / IG ratio of the nitrogen-doped carbon material is from 0.95 to 1.25.

[0126] ID / IG refers to the Raman spectroscopy used to measure nitrogen-doped carbon materials at a wavenumber of 1345 cm⁻¹. -1 The disordered D-band intensity on the left and right and 1590cm -1 The ratio of the graphitized G-band intensity on the left and right sides indicates the degree of graphitization; the lower the ratio, the higher the degree of graphitization.

[0127] Graphitization degree is an indicator that measures the extent to which carbon materials, through structural rearrangement, approach perfect graphite in crystal form. It reflects the degree of perfection of graphite crystals in a material; the higher the degree of graphitization, the better the electrical conductivity of the material.

[0128] The nitrogen-doped carbon material of this application has a high degree of graphitization, indicating that it has good electrical conductivity, that is, the conductive porous material has good electrical conductivity. The conductivity of the catalyst can be improved by using conductive porous materials, thereby improving the catalytic performance.

[0129] The values ​​from 0.95 to 1.25 mentioned above include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, as well as 0.95, 1.0, 1.1, 1.2, 1.25, etc., and the range values ​​between any two of the above point values.

[0130] In one embodiment, the nitrogen doping mass of the nitrogen-doped carbon material is 10% to 15%.

[0131] The doping quality of nitrogen in nitrogen-doped carbon materials can be tested using elemental analysis (e.g., energy dispersive spectroscopy). N can coordinate with active substances, thereby controlling the active sites and stability of the active substances. The higher the N content, the more sites there are for coordination with the active substances, which facilitates the improvement of the loading and coordination stability of the active substances.

[0132] The values ​​in the range of 10% to 15% include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments and 10%, 11%, 12%, 13%, 14%, 15%, etc., as well as the range values ​​between any two of the above point values.

[0133] In one embodiment, the catalyst has a specific surface area of ​​550 m². 2 / g to 650m 2 / g.

[0134] Specific surface area can be determined by N2 adsorption method, and for details, please refer to GB / T 19587-2017 "Determination of specific surface area of ​​solid substances by gas adsorption BET method".

[0135] The specific surface area of ​​the catalyst meets the above range. The nitrogen-doped carbon material has a porous structure containing micropores and mesopores, which effectively increases the specific surface area of ​​the material. The increase in specific surface area can effectively improve the loadable area of ​​the active material and the contactability between the electrolyte and the active material, which is conducive to improving the utilization rate of the active material.

[0136] The above 550m 2 / g to 650m 2 In / g, the values ​​include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments and 550m. 2 / g、580m 2 / g、600m 2 / g、630m 2 / g、650m 2 / g, etc., and the range of values ​​between any two of the above point values.

[0137] In one embodiment, the particle size Dv50 of the catalyst is from 5 nm to 25 nm.

[0138] The catalyst particle size meets the above range. Small-sized catalyst particles help transport reactants and products, thereby increasing the reaction rate.

[0139] Dv50 is the particle size at which the cumulative particle size distribution percentage of a sample reaches 50%. Physically, it means that 50% of the particles are larger than Dv50, and 50% are smaller than Dv50.

[0140] The catalyst is in the form of nanoparticles, and its particle size refers to the diameter of the particles. It is generally characterized by transmission electron microscopy. By statistically analyzing the particle diameter distribution in different test areas and drawing a particle size distribution statistical chart, the particle size distribution range can be obtained.

[0141] In one embodiment, the core layer structure is a porous structure, and the particle size Dv50 of the core layer structure is 5 nm to 20 nm.

[0142] The core layer structure is a porous structure with a particle size that meets the above-mentioned range. The core layer structure includes CeO2, which has the function of storing and releasing oxygen. The internal pores of the CeO2 structure are micropores and mesopores with a particle size in the nanometer range, which helps to increase the specific surface area of ​​the core layer structure and thus improve the oxygen storage and release capacity.

[0143] The values ​​in the range of 5nm to 20nm include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 5nm, 8nm, 10nm, 15nm, 18nm, 20nm, etc., as well as the range values ​​between any two of the above point values.

[0144] In one embodiment, the specific surface area of ​​the core layer structure is 60 m². 2 / g to 80m 2 / g.

[0145] The specific surface area of ​​the core layer structure meets the above range. The core layer structure includes CeO2, which has the function of storing and releasing oxygen. The specific surface area is increased, thereby improving the oxygen storage and release capacity.

[0146] The above 60m 2 / g to 80m 2 In / g, the values ​​include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments and 60m. 2 / g、65m 2 / g、70m 2 / g、75m 2 / g、80m 2 / g, etc., and the range of values ​​between any two of the above point values.

[0147] In one embodiment, the thickness of the conductive porous material is 1 nm to 5 nm.

[0148] The thickness of conductive porous materials can be measured using transmission electron microscopy (TEM), which allows observation of the core-shell structure. Specifically, due to differences in the materials of the core and shell structures, a contrast (mass-thickness contrast) will appear between the core and shell structures in the TEM image. This contrast is caused by the difference in thickness and mass across different regions of the sample surface. Because different parts of the sample have different electron scattering capabilities, the number of electrons transmitted through the objective lens also varies, resulting in differences in electron beam intensity. Areas with strong scattering and fewer transmitted electrons appear darker, while those with weaker scattering and fewer transmitted electrons appear brighter. The size of the shell structure can be measured using images of catalyst particles obtained through TEM.

[0149] A thickness within the aforementioned range for conductive porous materials helps improve conductivity and mass-charge transport capabilities during the catalytic process. Understandably, the thickness of the conductive porous material affects these properties; it should not be too thick, otherwise it will increase resistance to mass-charge transport.

[0150] In one embodiment, the mass percentage of the active material in the catalyst is 1.2% to 16%.

[0151] To determine the mass percentage of active material in a catalyst, the catalyst is digested to dissolve the active material in the digestion solution, forming a test solution. The mass of the active material is then measured using ICP-OES, allowing the mass percentage of active material in the catalyst to be calculated.

[0152] The mass percentage of active material in the catalyst meets the above-mentioned range, and the active material in the catalyst can still maintain good catalytic activity at the above-mentioned mass percentage. It is understood that, in one embodiment, based on nitrogen-doped carbon material as conductive porous material, the active material, through coordination with N, helps to stably locate in the pores and / or surface of the conductive porous material, and the catalyst can still maintain good catalytic performance during long-term operation.

[0153] The values ​​in the range of 1nm to 5nm include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, as well as 1nm, 2nm, 3nm, 4nm, 5nm, etc., and the range values ​​between any two of the above point values.

[0154] The values ​​in the range of 1.2% to 16% include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 1.2%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, etc., as well as the range values ​​between any two of the above point values.

[0155] In one embodiment, the active material includes noble metal atoms, and the mass percentage of the active material in the catalyst is 1.2% to 3%. Noble metal atoms have higher utilization of active sites, lower loading, and better catalytic performance.

[0156] In one embodiment, the active material comprises sub-nano clusters, and the mass percentage of the active material in the catalyst is 3% to 5%.

[0157] Sub-nanometer clusters are clusters with sizes between metal atoms and nanoparticles, typically containing several to hundreds of atoms, and with a size of less than 1 nanometer.

[0158] In one embodiment, the active material comprises nanoparticles, and the mass percentage of the active material in the catalyst is 6% to 12%.

[0159] In one embodiment, the ion exchange membrane includes anion exchange membrane or cation exchange membrane.

[0160] The values ​​in the range of 1.2% to 3% include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, as well as 1.2%, 2%, 2.5%, 3%, etc., and the range values ​​between any two of the above point values.

[0161] The values ​​in the range of 3% to 5% include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, as well as 3%, 4%, 5%, etc., and the range values ​​between any two of the above point values.

[0162] The values ​​in the range of 6% to 12% include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments and 6%, 7%, 8%, 9%, 10%, 11%, 12%, etc., as well as the range values ​​between any two of the above point values.

[0163] For example, in one embodiment, in proton exchange membrane electrolysis for hydrogen production (PEMWE), the core components mainly include membrane electrodes, diffusion layers, and bipolar plates. Among these, the anodic oxygen evolution reaction (OER) in the membrane electrode is the main energy-consuming and rate-determining step compared to the cathodic hydrogen evolution reaction (HER). Therefore, finding an efficient and stable anodic OER catalyst is crucial for improving the OER rate. Iridium (Ir)-based catalysts exhibit high catalytic activity in acidic media, but Ir is expensive, has low availability, and insufficient catalytic stability. Therefore, reducing the amount of Ir in the PEMWE catalyst and improving its catalytic activity and stability is of great significance. In this application, the core layer structure includes CeO2, which has strong oxygen storage and release capabilities and corrosion resistance. The nitrogen-doped carbon material derived in situ from high-temperature pyrolysis exhibits excellent conductivity, significantly improving the catalyst's activity and stability.

[0164] In one embodiment, this application also provides a catalyst, which includes a core structure and a shell structure disposed on the surface of the core structure, wherein the pores and / or surface of the shell structure are provided with an active substance; the core structure includes rare earth oxides, and the shell structure includes conductive porous materials; the active substance includes at least one of noble metal atoms, noble metal elements, and noble metal alloys.

[0165] In one embodiment, the conductive porous material comprises a nitrogen-doped carbon material.

[0166] In one embodiment, the rare earth oxide includes at least one of CeO2, La2O3, Ce2O3, Nd2O3, Eu2O3, and Gd2O3.

[0167] In one embodiment, the noble metal element in the noble metal atom, noble metal element, or noble metal alloy includes at least one of Ir, Ru, Pd, and Pt.

[0168] In one embodiment, nitrogen-doped carbon material I D / I G It ranges from 0.95 to 1.25.

[0169] In one embodiment, the nitrogen doping mass of the nitrogen-doped carbon material is 10% to 15%.

[0170] In one embodiment, the catalyst has a specific surface area of ​​550 m². 2 / g to 650m 2 / g.

[0171] In one embodiment, the particle size Dv50 of the catalyst is from 5 nm to 25 nm.

[0172] In one embodiment, the core layer structure is a porous structure with a particle size of 5 nm to 20 nm. In another embodiment, the specific surface area of ​​the core layer structure is 60 m². 2 / g to 80m 2 / g.

[0173] In one embodiment, the thickness of the conductive porous material is 1 nm to 5 nm.

[0174] In one embodiment, the mass percentage of the active material in the catalyst is 1.2% to 16%.

[0175] In one embodiment, such as Figure 10 As shown, this application also provides a method for preparing a catalyst, comprising: dispersing rare earth oxides, a metal source, and an organic ligand in a solvent, stirring, and drying to obtain a catalyst precursor, wherein the metal source includes an active material source; and calcining the catalyst precursor under an inert atmosphere to obtain the catalyst.

[0176] Metal sources and organic ligands are used to prepare metal-organic frameworks (MOFs), which are porous crystalline materials formed by the self-assembly of metal ions or metal clusters with organic ligands. For example, metal sources provide metal ions, serving as raw materials for the preparation of MOFs.

[0177] The active material source includes metal elements, which are the metal elements that play a catalytic role. The active material source is used to provide the raw materials for the active material, referring to the introduction of the active material into a metal-organic framework compound.

[0178] In the catalyst preparation process, rare earth oxides can be prepared first. The rare earth oxides, metal sources, and organic ligands are dispersed in a solvent, stirred, and dried to generate metal-organic framework compounds on the surface of the rare earth oxides. Active substances are then introduced into the metal-organic framework compounds to obtain the catalyst precursor.

[0179] The catalyst precursor is calcined in an inert atmosphere, so that the metal-organic framework compound is pyrolyzed at high temperature to become a conductive porous carbon material, and the active material is located on the surface and / or pores of the conductive porous carbon material, thus obtaining the catalyst.

[0180] This application describes the in-situ growth of metal-organic framework compounds on the surface of rare earth oxides. The active material source serves as a metal source and acts as a metal node in the metal-organic framework compound, which helps to improve the dispersion uniformity of the active material in the metal-organic framework compound, increase the utilization rate of the active material, and reduce the loading of the active material.

[0181] In one embodiment, the metal source further includes an inactive material source. The metal element in the inactive material source can be a metal element without catalytic activity. The metal in the inactive material source also serves as a metal node in the metal-organic framework compound. The introduction of the inactive material can reduce the amount of active material used, while improving the uniformity of the distribution of the active material and regulating the catalytic performance. It is understood that, for example, if the active element includes Ir and the inactive element includes Zn, and the metal nodes in the metal-organic framework compound include Zn and Ir, nodes with Zn and Ir cross-distribution can be formed. Zn acts as a separator for Ir sites, preventing the aggregation of Ir sites and facilitating the regulation of the size of Ir active sites. Pure Ir without the Zn spacing cannot regulate the size of single atoms, sub-nanometer clusters, and nanoparticles.

[0182] In one embodiment, the molar ratio of the metal in the inactive source to the metal in the active source is greater than 4 and less than 16. This helps to control the size of the active material at the single-atom level, resulting in higher utilization of active sites, lower loading, and better catalytic performance in single-atom catalysts.

[0183] In one embodiment, the molar ratio of the metal in the inactive material source to the metal in the active material source is greater than or equal to 2 and less than or equal to 4. The size of the active material can be controlled to form sub-nanometer clusters.

[0184] In one embodiment, the molar ratio of the metal in the inactive material source to the metal in the active material source is greater than 0.1 and less than 2. The size of the active material can be controlled to form a nanoscale.

[0185] In one embodiment, the organic ligand comprises an organic compound containing carbon and nitrogen.

[0186] Organic ligands include organic compounds containing carbon and nitrogen. Thus, during the formation of metal-organic frameworks, metal ions coordinate with nitrogen, which is an in-situ coordination of metal and nitrogen. Even after calcination and carbonization, they can still coordinate with nitrogen, which helps to regulate the active sites of active substances and enhance their stability.

[0187] In one embodiment, the molar ratio of the organic ligand to the metal source is 2:1 to 16:1.

[0188] Understandably, a suitable molar ratio of organic ligands to metal sources can facilitate the preparation of metal-organic framework compounds.

[0189] In one embodiment, each 100 mg of rare earth oxide corresponds to 2 mmol to 160 mmol of organic ligand and 1 mmol to 10 mmol of metal source. This helps to prepare a conductive porous material with a suitable thickness on the surface of the rare earth oxide, which helps to improve conductivity and mass-charge transport capabilities during the catalytic process. It is understood that the ratio of the metal-organic framework compound feedstock to the mass of the rare earth oxide affects the thickness of the metal-organic framework compound formed on the surface of the rare earth oxide, and thus affects the thickness of the conductive porous material after carbonization (the metal-organic framework compound becomes a conductive porous material after carbonization), thereby affecting conductivity.

[0190] In one embodiment, the rare earth oxide includes at least one of CeO2, La2O3, Ce2O3, Nd2O3, Eu2O3, and Gd2O3.

[0191] In one embodiment, the metal element in the inactive material source includes at least one of Zn, Co, Ni, Cu, Mn, Ti, Ta, and Nb.

[0192] In one embodiment, the metal element in the active material source includes at least one of Ir, Ru, Pd, and Pt.

[0193] In one embodiment, the organic ligand includes at least one of dimethylimidazole, pyridine, pyrrole, and phthalocyanine.

[0194] In one embodiment, the calcination temperature of the catalyst precursor in an inert atmosphere is 800°C to 900°C.

[0195] During high-temperature pyrolysis, rare earth oxides are stable, while the organic ligands in metal-organic framework compounds undergo carbonization and decomposition to form conductive porous materials.

[0196] It is also understandable that the inactive metal nodes (such as Zn) in metal-organic framework compounds will volatilize because the calcination temperature reaches the boiling point of the inactive material but not the boiling point of the active material (such as Ir). Therefore, the active material is retained and coordinated by N in the organic ligand.

[0197] Simultaneously, the coordination number of N can be controlled by adjusting the calcination temperature. Adjusting the coordination number of N at the aforementioned temperatures allows for uniform loading of active materials. For example, in-situ growth of metal-organic framework compounds on a CeO2 substrate followed by high-temperature pyrolysis produces a carbon-nitrogen substrate with excellent conductivity, enhancing the catalyst's conductivity. Furthermore, the coordination of nitrogen-containing ligands in organometallic covalent compounds ensures uniform distribution of Ir sites, improving the utilization rate of active sites and reducing the Ir loading.

[0198] Furthermore, the inactive substances (such as Zn) in the metal-organic framework volatilize during the high-temperature carbonization process, which enhances the porous characteristics of the conductive porous material while ensuring the uniform distribution of Ir sites. This is beneficial for increasing the specific surface area, which can effectively improve the load-bearing area of ​​the active material and the contactability between the electrolyte and the active material, thereby improving the utilization rate of the active material.

[0199] The values ​​in the range of 800℃ to 900℃ include the minimum and maximum values ​​of this range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, as well as 800℃, 850℃, 900℃, etc., and the range values ​​between any two of the above point values.

[0200] In one embodiment, this application also provides an anode catalyst for water electrolysis, which includes the catalyst as described above, or the anode catalyst for water electrolysis includes a catalyst prepared by the method described above.

[0201] Optionally, this application also provides an application of the water electrolysis device as described above.

[0202] Understandably, water electrolysis devices can be coupled with wind and solar renewable energy sources to produce hydrogen through water electrolysis. The produced hydrogen can be used as a raw material for fuel cells in transportation and energy storage, and it can also be used as a raw material in chemical (synthetic ammonia, synthetic methanol, etc.) and refining industries.

[0203] Example

[0204] Example 1

[0205] Catalyst preparation

[0206] Preparation of core layer structure (CeO2)

[0207] 0.75 g (2 mmol) of cerium chloride heptahydrate (CeCl3·H2O) was dissolved in 10 mL of ethanol under magnetic stirring. Then, 3 mL of ethylenediamine (C2H8N2) was added under vigorous stirring, and stirring was continued for about 20 minutes to form a homogeneous solution. Then, 2 mL of hydrazine hydrate (N2H4·H2O, 85%) was added, and stirring was continued for 15 minutes. The mixture was transferred to a 25 mL reactor and heated at 180 °C for 8 hours. After cooling to room temperature, the precipitate was centrifuged, washed three times with water and ethanol, and dried in a vacuum drying oven at 60 °C for 12 hours to obtain CeO2 nanoparticles for later use.

[0208] Preparation of catalyst precursors

[0209] 200 mg of the synthesized CeO2 nanoparticles were dispersed in 30 mL of methanol and sonicated for 20 min to ensure uniform dispersion. Then, 0.297 g (1 mmol) of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) and 0.489 g (1 mmol) of iridium acetylacetone (Ir(acac)3) were added, and the mixture was stirred at room temperature for 30 min to ensure uniform dissolution of the metal salts. Next, 0.769 g (8 mmol) of dimethylimidazole (C4H6N2) was added, and the mixture was stirred at room temperature for 24 h. After the reaction was complete, the mixture was centrifuged, washed three times with methanol, and dried in a vacuum drying oven at 60 °C for 12 h to obtain the CeO2@ZIF-Zn / Ir core-shell structure metal-organic framework precursor.

[0210] The catalyst precursor was calcined in an inert atmosphere to obtain the catalyst. The CeO2@ZIF-Zn / Ir precursor was then transferred into a tube furnace and calcined at 900°C for 3 hours in a nitrogen atmosphere, during which Zn atoms volatilized at high temperature. After cooling to room temperature, a CeO2@CN-Ir single-atom catalyst was formed.

[0211] Catalyst performance testing

[0212] Catalyst size: The morphology and size of the catalyst were characterized using transmission electron microscopy (TEM). The accelerating voltage was 100 kV. The morphology and size are shown in the figure. Figure 2 As shown, the morphology is nanoparticle-like, with a size of approximately 10 nm.

[0213] Crystal structure of the catalyst: The crystal structure of the catalyst was determined using X-ray powder diffraction (XRD). Cu-Kα was used as the radiation source, the operating voltage was 40 kV, the current was 25 mA, the 2θ scanning range was 5–80°, and the scan rate was 5° / min. -1 The measured XRD pattern is as follows Figure 3 As shown, the core structure corresponds to the CeO2 fluorite structure, and the standard card is PDF#43-1002. The outer Ir layer is distributed as single atoms with no obvious structural characteristic peaks. After high-temperature carbonization, the carbon peak corresponding to the carbon-nitrogen substrate is around 20°. EDS characterization shows that Ir element has been successfully introduced.

[0214] Elemental distribution in the catalyst: The elemental distribution in the sample was characterized using energy-dispersive spectroscopy (EDS) at an accelerating voltage of 200 kV. The elemental distribution is shown in the figure. Figures 5 to 7 As shown, the catalyst structure clearly contains two metal elements, Ir and Ce, indicating the successful introduction of the Ir shell layer.

[0215] Preparation of a three-electrode electrolytic cell

[0216] Catalyst slurry preparation

[0217] 4 mg of the prepared CeO2@CN-Ir catalyst powder and 10 μL of Nafion solution (5 wt.%) were ultrasonically dispersed in 400 μL of isopropanol for about 1 hour at a temperature not exceeding 30°C to ensure uniform dispersion of the catalyst slurry for later use.

[0218] Three-electrode device structure

[0219] Working electrode: Glassy carbon electrode (3 mm in diameter). Take 2 μL of the catalyst slurry prepared above and evenly drop it onto the polished and cleaned glassy carbon electrode. Then, drop 1 μL of 0.3% Nafion isopropanol solution onto the working electrode and allow it to dry in air until ready for use. The catalyst loading is approximately 0.28 mg / cm³. 2 ;

[0220] Counter electrode: Pt sheet electrode

[0221] Reference electrode: Saturated calomel electrode

[0222] Electrolyte: 0.1M perchloric acid solution (0.1M HClO4).

[0223] Assembly: Take about 60 mL of electrolyte into a 100 mL five-hole electrolytic cell, and insert the working electrode, counter electrode and reference electrode in sequence for performance testing.

[0224] Performance testing

[0225] Linear Voltammetric Scan (LSV): The activity of the catalyst was evaluated using the linear voltammetric scan (LSV) method. The assembled three-electrode electrolytic cell was connected to an electrochemical workstation. Before testing, O2 was passed through the electrolyte for approximately 30–60 min to ensure an oxygen-saturated atmosphere. The voltage range was set to 1.3–1.8 V vs. RHE, and the scan rate was 5 mV / s. The catalyst was compared with the catalyst at a current density of 10 mA / cm². 2 The lower the overpotential, the better the catalytic activity. Figure 8 It can be seen that the CeO2@CN-Ir catalyst exhibits a lower overpotential compared to the CN-Ir catalyst supported on a carbon-nitrogen substrate and the pure CeO2 core substrate, indicating that the catalyst in this application has good stability.

[0226] Potentiochronoamperometry (CA): The stability of the catalyst was tested using a potentiochronoamperometry curve at a potential of 1.52 V vs. RHE (j = 10 mA / cm). 2 The current density of the catalyst was evaluated over time. Figure 8 It can be seen that after 40 hours of operation, the CeO2@CN-Ir catalyst still retains 95% of the current density, indicating that the catalyst of this application has good stability.

[0227] Example 2 and Example 3

[0228] Based on Example 1, the loading of active substances was adjusted.

[0229] Examples 4 and 5

[0230] Based on Example 1, the particle size of the catalyst was adjusted.

[0231] Example 6

[0232] Based on Example 1, Ir is replaced with Pd.

[0233] Example 7

[0234] Based on Example 1, CeO2 was replaced with La2O3. The 0.1M perchloric acid solution (0.1M HClO4) in the electrolyte was replaced with 1.0M potassium hydroxide (1.0M KOH).

[0235] Comparative Example 1

[0236] Based on Example 1, the catalyst is free of CeO2.

[0237] Comparative Example 2

[0238] Based on Example 1, the catalyst is CeO2.

[0239] Comparative Example 3

[0240] Based on Example 7, the catalyst is free of La2O3.

[0241] Comparative Example 4

[0242] Based on Example 6, the catalyst is free of CeO2.

[0243] Table 1 List of Examples

[0244]

[0245] In the performance list in Table 1, the lower the overpotential, the better the catalytic activity; the higher the current density retention rate, the better the catalyst stability. As can be seen from Table 1, under the same Ir loading, Example 3 has a lower overpotential than Comparative Example 1, indicating that Example 3 has better catalytic activity. In addition, Example 3 has a higher current density retention rate than the Comparative Example, indicating that the catalyst stability of the Examples is better. The improvement in catalyst stability helps to improve the service life of the water electrolysis device.

[0246] Comparing Example 6 and Comparative Example 4, under the same Pd loading, the performance of the Example 6 is superior to that of the Comparative Example 4. Comparing Example 7 and Comparative Example 3, under alkaline conditions, the performance of the Example 7 is superior to that of the Comparative Example 3.

[0247] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A water electrolysis device, characterized in that, The device includes a membrane electrode, which comprises an ion exchange membrane and a catalyst layer disposed on the ion exchange membrane. The catalyst layer comprises a catalyst, which comprises a core structure and a shell structure disposed on the surface of the core structure. The pores and / or surface of the shell structure are provided with active substances. The core structure comprises rare earth oxides, and the shell structure comprises conductive porous materials. The active substance includes at least one of noble metal atoms, noble metal elements, and noble metal alloys.

2. The water electrolysis device as described in claim 1, characterized in that, The conductive porous material includes nitrogen-doped carbon materials; And / or, the rare earth oxides include at least one of CeO2, La2O3, Ce2O3, Nd2O3, Eu2O3, and Gd2O3; And / or, the noble metal atom, the noble metal element, or the noble metal alloy includes at least one of Ir, Ru, Pd, and Pt.

3. The water electrolysis device as described in claim 2, characterized in that, The nitrogen-doped carbon material I D / I G The value ranges from 0.95 to 1.25; And / or, the nitrogen doping mass in the nitrogen-doped carbon material is 10% to 15%.

4. The water electrolysis apparatus according to any one of claims 1 to 3, characterized in that, The catalyst has a specific surface area of ​​550 m². 2 / g to 650m 2 / g; And / or, the particle size Dv50 of the catalyst is from 5 nm to 25 nm; And / or, the core layer structure is a porous structure, and the particle size Dv50 of the core layer structure is 5 nm to 20 nm; And / or, the specific surface area of ​​the core layer structure is 60 m². 2 / g to 80m 2 / g; And / or, the thickness of the conductive porous material is 1 nm to 5 nm; And / or, the mass percentage of the active material in the catalyst is 1.2% to 16%.

5. The water electrolysis apparatus according to any one of claims 1 to 4, characterized in that, The active material includes noble metal atoms, and the mass percentage of the active material in the catalyst is 1.2% to 3%. Alternatively, the active material may be present in the form of sub-nano clusters, and the mass percentage of the active material in the catalyst may be 3% to 5%. Alternatively, the active material may be present in the form of nanoparticles, and the mass percentage of the active material in the catalyst may be 6% to 12%.

6. A catalyst, characterized in that, The catalyst includes a core structure and a shell structure disposed on the surface of the core structure, wherein the pores and / or surface of the shell structure are provided with active substances; The core structure comprises rare earth oxides, and the shell structure comprises conductive porous materials. The active substance includes at least one of noble metal atoms, noble metal elements, and noble metal alloys.

7. The catalyst as claimed in claim 6, characterized in that, The conductive porous material includes nitrogen-doped carbon materials; And / or, the rare earth oxides include at least one of CeO2, La2O3, Ce2O3, Nd2O3, Eu2O3, and Gd2O3; And / or, the noble metal atom, the noble metal element, or the noble metal alloy includes at least one of Ir, Ru, Pd, and Pt; And / or, the nitrogen-doped carbon material I D / I G The value ranges from 0.95 to 1.

25. And / or, the nitrogen doping mass in the nitrogen-doped carbon material is 10% to 15%; And / or, the catalyst has a specific surface area of ​​550 m². 2 / g to 650m 2 / g; And / or, the particle size Dv50 of the catalyst is from 5 nm to 25 nm; And / or, the core layer structure is a porous structure, and the particle size Dv50 of the core layer structure is 5 nm to 20 nm; And / or, the specific surface area of ​​the core layer structure is 60 m². 2 / g to 80m 2 / g; And / or, the thickness of the conductive porous material is 1 nm to 5 nm; And / or, the mass percentage of the active material in the catalyst is 1.2% to 16%.

8. A method for preparing a catalyst, characterized in that, include: Rare earth oxides, metal sources, and organic ligands are dispersed in a solvent, stirred, and dried to obtain a catalyst precursor, wherein the metal source includes an active material source. The catalyst precursor was calcined in an inert atmosphere to obtain the catalyst.

9. The method for preparing the catalyst according to claim 8, characterized in that, The metal source also includes a source of inactive substances. The molar ratio of the metal in the inactive material source to the metal in the active material source is greater than 4 and less than 16. Alternatively, the molar ratio of the metal in the inactive material source to the metal in the active material source is greater than or equal to 2 and less than or equal to 4. Alternatively, the molar ratio of the metal in the inactive material source to the metal in the active material source is greater than 0.1 and less than 2.

10. The method for preparing the catalyst according to claim 8 or 9, characterized in that, The organic ligands include organic compounds containing carbon and nitrogen elements; And / or, the molar ratio of the organic ligand to the metal source is 2:1 to 16:1; And / or, each 100 mg of the rare earth oxide corresponds to 2 mmol to 160 mmol of the organic ligand and 1 mmol to 10 mmol of the metal source; And / or, the rare earth oxides include at least one of CeO2, La2O3, Ce2O3, Nd2O3, Eu2O3, and Gd2O3; And / or, the metal element in the inactive material source includes at least one of Zn, Co, Ni, Cu, Mn, Ti, Ta, and Nb; And / or, the metal element in the active material source includes at least one of Ir, Ru, Pd, and Pt; And / or, the organic ligand includes at least one of dimethylimidazolium, pyridine, pyrrole, and phthalocyanine; And / or, in the step of calcining the catalyst precursor in an inert atmosphere, the calcination temperature is 800°C to 900°C.

11. An anode catalyst for water electrolysis, characterized in that, The anode catalyst for water electrolysis comprises the catalyst as described in claim 6 or 7, or the anode catalyst for water electrolysis comprises a catalyst prepared by the method of preparing the catalyst as described in any one of claims 8 to 10.

12. Application of a water electrolysis apparatus as described in any one of claims 1 to 5.

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