A cathode material for a solid oxide fuel electrolyzer, a preparation method thereof, and an application thereof

Abstract

The present invention discloses a cathode material for a solid oxide fuel electrolyzer, a preparation method thereof, and an application thereof. The cathode material includes a cubic perovskite-type B-site high-entropy oxide and FeM nanoparticles in-situ precipitated on the surface. The chemical formula of the cubic perovskite-type B-site high-entropy oxide is Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 M 0.2 )O 3‑δ , and M is one of Ni, Cu, Co, and Ru. During the preparation, a Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 M 0.2 )O4 precursor is first prepared; then the precursor is in-situ formed into a cathode material by an electrode polarization-in-situ reduction method. The vanadium-based cubic perovskite-type B-site high-entropy oxide prepared by the present invention has higher catalytic activity for CO2 reduction, and its conductivity is two orders of magnitude higher than that of ordinary perovskites. At the same time, it has strong stability under high-temperature conditions. Therefore, this cathode material takes into account conductivity, catalytic activity, and stability at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of electrode materials, and particularly to a cathode material for a solid oxide fuel electrolyzer, a preparation method thereof, and an application thereof. Background Art

[0002] Solid oxide electrolyzers (SOECs) have the advantages of low overpotential, high Faraday efficiency, and high-temperature operation being beneficial to improving energy efficiency. They can directly reduce CO 2 to CO, and have broad practical application prospects in CO 2 conversion and renewable electric energy storage. Based on the current country's "dual-carbon" strategy, the resource utilization of CO 2 by high-temperature electrolysis is not only beneficial to environmental protection but also conducive to creating additional economic benefits. The generated CO can not only be used as a direct fuel gas but also as a raw material to produce high-value-added chemical products.

[0003] The electrochemical activity and durability of SOECs towards CO 2 are largely limited by the cathode. Currently, traditional nickel-based cermet fuel electrodes have poor stability and anti-carbon deposition performance, while perovskite-type oxide electrodes have good anti-carbon deposition performance but insufficient catalytic activity. In particular, vanadate perovskite-type oxides, although having high electronic conductivity, have low catalytic reduction activity and large polarization losses during the electrolysis process. Therefore, it is urgent to design and develop SOEC cathode materials with high activity and stability. Summary of the Invention

[0004] The purpose of the present invention is to propose a cathode material for a solid oxide fuel electrolyzer with more excellent CO 2 electrocatalytic reduction activity, and a preparation method and application thereof that are simple and efficient.

[0005] A cathode material for a solid oxide fuel electrolyzer according to the present invention, wherein the cathode material includes a cubic perovskite structure B-site high-entropy oxide and a nano-alloy in-situ precipitated on the surface of the high-entropy oxide. The chemical formula of the cubic perovskite-type B-site high-entropy oxide is Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 M 0.2 )O 3-δ , and the nano-alloy is a multi-component alloy FeM nanoparticle, and M is one of Ni, Cu, Co, and Ru.

[0006] Further, the cubic perovskite-type B-site high-entropy oxide is composed of a high-entropy oxide with a scheelite structure Sr(Fe 0.2 V 0.2 Mo 0.2Ti 0.2 M 0.2 )O 4 Reductive generation.

[0007] Furthermore, the size of the multi-component alloy FeM nanoparticles ranges from 50 to 150 nm.

[0008] A preparation method of the cathode material for a solid oxide fuel electrolyzer as described above, comprising the following steps:

[0009] S1. Prepare a scheelite-structured high-entropy oxide Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 M 0.2 )O 4 Precursor;

[0010] S2: Mix and grind the precursor and the binder to prepare a slurry, coat it on the surface of the electrolyte and dry it to prepare a cell;

[0011] S3: Electrochemically polarize and reduce the cell at a certain operating temperature and in a reducing atmosphere, apply a certain current, and in-situ form a multi-component alloy FeM particle-coated cubic perovskite-structured B-site high-entropy oxide Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 M 0.2 )O 3-δ .

[0012] Furthermore, in step S1, a sol-gel-laser treatment technique is used to prepare a scheelite-structured high-entropy oxide Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 M 0.2 )O 4 Precursor.

[0013] Furthermore, the specific operation of preparing the scheelite-structured high-entropy oxide Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 M 0.2 )O 4 Precursor is as follows:

[0014] S11: Dissolve a certain amount of citric acid in an aqueous ethanol solution, and then dissolve Sr source, Fe source, V source, Mo source, Ti source, and M source according to the stoichiometric ratio. After all the above metal sources are completely dissolved, heat and stir until clear and heat to obtain a gel;

[0015] S12: Laser process the gel to obtain a high-entropy oxide precursor Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 M 0.2 )O 4 powder.

[0016] Furthermore, in step S11, the molar ratio of citric acid to metal ions is (1.5 - 2):1; in step S12, place the gel in a quartz glass groove and perform laser processing; the laser power for the laser processing is 10 - 15 W, the scanning speed is 30 - 40 mm s -1 , the frequency is 10 - 20 kHz, and the processing time is 10 - 20 min.

[0017] Furthermore, in step S2, the binder is terpineol containing 7.5 - 10 wt.% ethyl cellulose; the mass ratio of the precursor to the binder is 1:(1.5 - 2).

[0018] Furthermore, in step S3, the working temperature is 800 - 900 °C, the reducing atmosphere is pure hydrogen, and the applied current for electrochemical polarization is 20 - 50 mA cm -2 , and the polarization time is 60 - 180 min.

[0019] An application of the cathode material of the solid oxide fuel electrolytic cell as described above, used for the cathode of a solid oxide fuel cell to perform CO 2 electrolysis or CO 2 -H 2 O co-electrolysis.

[0020] The present invention has the following beneficial effects:

[0021] 1. Prepare an alloy-modified high-entropy oxide cathode by the electrode polarization-in-situ reduction method. In the cell operating temperature range (800 - 900 °C), hydrogen in-situ reduces to form a perovskite-type high-entropy oxide and metal nanoalloys precipitate on the surface, and the scheelite-structured high-entropy oxide is in-situ transformed into a cubic perovskite-type B-site high-entropy oxide by reduction atmosphere electrolysis. The vanadium-based cubic perovskite-type B-site high-entropy oxide Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 M 0.2 )O 3-δ prepared by the present invention has a catalytic effect on CO 2It has higher reduction activity, and its conductivity is two orders of magnitude higher than that of ordinary perovskites. At the same time, high-entropy materials have strong stability under high-temperature operating conditions, and the high-entropy configuration also has unique advantages in suppressing the decline of electrode performance and improving electrode stability. Therefore, this cathode material takes into account conductivity, catalytic activity, and stability at the same time.

[0022] 2. Efficient and rapid preparation of new materials is very important for the development of materials and the progress of science and technology. The traditional sintering temperature of high-entropy oxides is generally greater than 1100 °C. The present invention uses laser treatment technology to avoid traditional high-temperature calcination of precursors, with a short irradiation period and high intensity, and efficiently and rapidly prepares high-entropy oxides. The laser power required for the entire reaction process is 10-15 W, which is suitable for large-scale production. Laser treatment makes the precursor powder structure of Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 M 0.2 )O 3-δ more porous and loose, which can increase the catalytic specific surface area and is conducive to charge transfer in catalytic reactions. Lasers can also regulate the oxygen defect concentration, thereby improving catalytic activity.

[0023] 3. Compared with the conventional in-situ precipitation process, the electrode polarization-in-situ reduction process of the present invention is simple, efficient, and time-saving in operation. It can simultaneously achieve the phase transformation of high-entropy oxides and the precipitation of metal particles at a lower operating temperature and in a shorter time. The high-entropy oxide system modified with nano-alloy particles can not only improve the electronic conductivity of the electrode but also improve the catalytic reduction ability of CO 2 . Brief Description of the Drawings

[0024] Figure 1a XRD pattern of the scheelite-structured high-entropy oxide Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 Ni 0.2 )O 4 powder prepared by the sol-gel laser method in Example 1;

[0025] Figure 1b is FeNi prepared by the electrode polarization-in-situ reduction method in Example 1 3 @Sr (Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 Ni 0.2 )O 3-δ XRD pattern of the powder;

[0026] Figure 2a XRD pattern of the scheelite-structured high-entropy oxide Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 Ni 0.2 )O 4 powder prepared by the sol-gel laser method in Example 1;

[0027] Figure 2b is FeNi prepared by the electrode polarization-in-situ reduction method of Example 1 3 @Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 Ni 0.2 ) O 3-δ SEM image of the powder

[0028] Figure 3a FeNi prepared in Example 1 3 @Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 Ni 0.2 )O 3-δ TEM image of the material

[0029] Figure 3b FeNi prepared according to the technical solution of this Example 1 3 @Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 Ni 0.2 )O 3-δ Elemental scanning distribution map

[0030] Figure 4 FeNi prepared in this Example 1 3 Elemental distribution map (Mapping) of alloy particles

[0031] Figure 5 EDS data map of each element on the surface of the cathode material prepared according to the technical solution of this Example 1

[0032] Figure 6a I-V diagram of the SOEC assembled in this Example 1 for direct electrolysis of CO at different temperatures 2

[0033] Figure 6b Stability test results of the SOEC assembled in Example 1 at 800 °C and an electrolysis voltage of 1.3 V

[0034] Figure 7 SEM image of the heterostructure powder of FeCu@Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 Cu 0.2 )O 3-δ prepared by the electrode polarization-in-situ reduction method in this Example

[0035] Figure 8 RuFe@Sr(Fe prepared by the electrode polarization-in-situ reduction method in this Example 0.2 V 0.2 Mo 0.2 Ti 0.2 Ru 0.2 )O​3-δ SEM image of the heterostructure powder. Detailed implementation mode

[0036] The following are specific embodiments of the present invention, in combination with the accompanying drawings, to further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.

[0037] Embodiment 1:

[0038] According to the chemical formula Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 Ni 0.2 )O 4 , respectively weigh Sr(NO 3 ) 3 , Fe(NO 3 ) 2 ·9H 2 O, NH 4 VO 3 , (NH 4 ) 2 MoO 4 ·4H 2 O, Ni(NO 3 ) 2 ·6H 2 O, C 16 H 36 O 4 Ti and dissolve them in 100 mL of ethanol-water solution (volume ratio of ethanol to water is 1:1) in turn. Add citric acid in a molar ratio of total metal ions to citric acid of 1:2 and stir until it becomes clear, then put it into a microwave oven to heat to obtain a gel. Place the gel on a grooved quartz glass, adjust the output power of the laser to 15 W, the scanning speed to 30 mm s -1 , the frequency to 20 kHz, and the processing time to 20 min to obtain a scheelite-structured high-entropy oxide Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 Ni 0.2 )O 4 precursor.

[0039] Take the Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 Ni 0.2 )O 4The precursor is added to terpineol containing 5-10 wt.% ethyl cellulose, and the mass ratio of the precursor to terpineol is 1:1.5. The mixture is ground for several hours to obtain the electrode paste. The paste is uniformly coated on the dense La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3 (LSGM) electrolyte side, and the other side is coated with PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.5 O 5+δ anode paste. The electrodes on both sides are dried to complete the preparation of the single cell.

[0040] The single cell is encapsulated. Hydrogen is first introduced at 850 °C at the cathode, and an external current of 50 mA cm -2 is applied for in-situ polarization. After 120 min of reduction, the precursor powder with a scheelite structure is reduced to a cubic perovskite-type high-entropy oxide Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 Ni 0.2 )O 3-δ , and metal nanoparticles FeNi 3 are simultaneously precipitated on the substrate surface. Then nitrogen is introduced to purge the excess hydrogen, and then CO 2 is introduced for SOEC electrolysis testing. The reduction phase transition process can be represented by Equation 1-1:

[0041]

[0042] See Appendix Figure 1a , which is the XRD pattern of the Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 Ni 0.2 )O 4 precursor prepared by the sol-gel laser method in an air atmosphere according to the technical solution of this embodiment. The results show that the precursor has a tetragonal scheelite structure with a space group of I4 1 / a. See Appendix Figure 1b , which is the XRD pattern of the reduced cathode prepared by electrode polarization-in-situ reduction according to the technical solution of this embodiment. The results show that the reduced oxide is transformed into a cubic perovskite structure with a space group of Pm3m. At the same time, the additional small peaks on the left and right are the peaks of the FeNi 3 metal. Therefore, after reduction, it contains two phases, where the main phase is the perovskite-type high-entropy oxide and the phase with a very small content is FeNi 3Alloy phase. It is proved that electrode polarization-in-situ reduction can achieve the formation of high-entropy perovskite-structured oxides and the precipitation of metals at lower temperatures and in shorter times.

[0043] See the appendix Figure 2a , which is the SEM image of the precursor after laser treatment prepared according to the technical solution of this embodiment for Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 Ni 0.2 )O 4 The precursor has a loose and porous structure with uniformly distributed pore sizes.

[0044] Figure 2b The FeNi 3 @Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 Ni 0.2 )O 3-δ SEM image of the heterostructure powder; a large number of small metal particles precipitate on the surface of the perovskite substrate.

[0045] Figure 3 is the TEM image of the surface of the FeNi 3 @Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 Ni 0.2 )O 3-δ cathode material. It can be seen from the figure that the iron-nickel alloy precipitates significantly on the surface of the perovskite, and the particle size is between 100 and 150 nm.

[0046] Figure 4 is the elemental distribution map (Mapping) of a single nano iron-nickel alloy particle prepared according to the technology of this embodiment. It can be seen from the figure that Fe and Ni elements are concentrated on the surface of the perovskite electrode substrate, indicating that Fe and Ni elements in the B site of the high-entropy oxide precipitate from the matrix and form an alloy.

[0047] Figure 5 is the energy spectrum data map of each element on the surface of the cathode material prepared according to the technology of this embodiment. By comparison, it is found that the intensities of Fe and Ni elements at EDS point 2 are stronger than those of other B-site elements, further proving the precipitation of the iron-nickel alloy.

[0048] Figure 6a This is the current-voltage diagram of a SOEC assembled in this embodiment for directly electrolyzing CO 2 ; Figure 6bExample 1: Stability test results of an assembled SOEC at 800 °C and an electrolysis voltage of 1.3 V. The SOEC cathode based on the nanoalloy@high-entropy perovskite heterostructure electrolyzes CO 2 with an electrolysis current density reaching 1.093 A cm at 1.5 V and 800 °C -2 and can stably electrolyze for more than 190 h under mild electrolysis conditions of 1.3 V.

[0049] Example 2:

[0050] According to the chemical formula Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 Cu 0.2 )O 4 , respectively weigh Sr(NO 3 ) 3 , Fe(NO 3 ) 2 ·9H 2 O, NH 4 VO 3 , (NH 4 ) 2 MoO 4 ·4H 2 O, CuCl 2 ·2H 2 O, C 16 H 36 O 4 Ti and dissolve them in 100 mL of a de-ethanol aqueous solution (volume ratio of ethanol to water is 1:1) in turn. Add citric acid in a ratio of 1:2 of metal ions to citric acid, stir until clear, and then put it into a microwave oven to heat to obtain a gel. Laser process the above gel with a laser intensity of 15 W, a scanning speed of 30 mm s -1 , a frequency of 20 kHz, and a processing time of 20 min to obtain scheelite-structured Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 Cu 0.2 )O 4 .

[0051] Take the Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 Cu 0.2 )O 4Add 5-10 wt.% ethyl cellulose in terpineol. The mass ratio of the catalyst to terpineol is 1:1.5. Mix and grind for several hours to obtain the electrode paste. Use the screen printing method to evenly coat the paste on one side of a dense LSGM electrolyte with a thickness of 240 μm, and dry the electrode. Then coat PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.5 O 5+δ on the other side, and dry the electrode to complete the preparation of the single cell. Assemble and test the single cell. First, introduce hydrogen into the cathode at 850 °C, apply an external current of 50 mA cm -2 for in-situ polarization. After 60 min of reduction, the high-entropy oxide with a scheelite structure transforms into a high-entropy oxide with a cubic perovskite structure Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 Cu 0.2 )O 3-δ . At the same time, an FeCu alloy precipitates on the surface. Then purge the excess hydrogen with nitrogen, and then introduce CO 2 for SOEC electrolysis test. The electrode polarization-in-situ reduction process can be represented by Equations 1-2:

[0052]

[0053] Figure 7 is the SEM image of the FeCu@Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 Cu 0.2 )O 3-δ heterostructure powder prepared by the electrode polarization-in-situ reduction method of this example; a large number of small metal particles precipitate on the perovskite substrate surface, and the metal particle size is 50-100 nm.

[0054] Example 3:

[0055] According to the chemical formula Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 Ru 0.2 )O 4 , weigh Sr(NO 3 ) 3 , Fe(NO 3 ) 2 ·9H 2 O, NH 4 VO 3 , (NH 4 )2 MoO 4 ·4H 2 O, RuCl 3 , C 16 H 36 O 4 MoO·4H₂O, RuCl₃, and C are successively dissolved in 100 mL of a de-ethanol aqueous solution (volume ratio of ethanol to water is 1:1). Citric acid is added in a ratio of metal ions to citric acid of 1:2. After continuous stirring until it becomes clear, it is put into a microwave oven to heat to obtain a gel. The gel is taken for laser treatment with a laser intensity of 15 W, a scanning speed of 30 mm / s, a frequency of 20 kHz, and a treatment time of 20 min to obtain a scheelite-structured Sr(Fe -1 V 0.2 V 0.2 Mo 0.2 Ti 0.2 Ru 0.2 )O 4 precursor.

[0056] The as-prepared Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 Ru 0.2 )O 4 precursor is added to terpineol with 5 - 10 wt.% ethyl cellulose, and the mass ratio of the catalyst to terpineol is 1:1.5. They are mixed and ground for several hours to obtain an electrode paste. The paste is uniformly coated on one side of a dense LSGM electrolyte with a thickness of 240 μm by screen printing, and the electrode is dried. Then PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.5 O 5+δ is coated on the other side. After the electrode is dried, the preparation of the single cell is completed. The single cell is assembled and tested. At 800 °C, H₂ (~3% H₂O) is first introduced into the cathode, and an external current of 25 mA / cm² is applied for in-situ polarization. After 120 min of reduction, the scheelite-structured precursor powder is transformed into a cubic perovskite-type high-entropy oxide Sr(Fe 2 (~3% H 2 O), an external current of 25 mA / cm² is applied for in-situ polarization. After 120 min of reduction, the scheelite-structured precursor powder is transformed into a cubic perovskite-type high-entropy oxide Sr(Fe -2 V 0.2 V 0.2 Mo 0.2 Ti 0.2 Ru 0.2 )O 3-δ ), and RuFe alloy is simultaneously precipitated on the surface. Then nitrogen is introduced to purge the excess hydrogen, and then CO 2 is introduced for electrolysis testing. The electrode polarization-in-situ reduction process can be expressed by Equations 1 - 3:

[0057]

[0058] Figure 8 SEM image of the RuFe@Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 Ru 0.2 )O 3-δ heterostructure powder; a large number of small metal particles are precipitated on the surface of the perovskite substrate, and the size of the metal particles is 50 - 80 nm.

[0059] Where not covered above, it shall apply to the prior art.

[0060] Although some specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and not for limiting the scope of the present invention. Those skilled in the technical field to which the present invention pertains can make various modifications or supplements to the described specific embodiments or use similar ways to substitute, but will not deviate from the direction of the present invention or exceed the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc. made in accordance with the technical essence of the present invention to the above embodiments shall be included in the protection scope of the present invention.

Claims

1. A cathode material for a solid oxide fuel electrolyzer, characterized in that: The cathode material includes a cubic perovskite-type B-site high-entropy oxide and a nanoalloy in-situ precipitated on the surface of the cubic perovskite-type B-site high-entropy oxide. The chemical formula of the cubic perovskite-type B-site high-entropy oxide is Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 M 0.2 )O 3-δ . The nanoalloy is a multi-component alloy FeM nanoparticle, and M is one of Ni, Cu, Co, and Ru.

2. The cathode material for a solid oxide fuel electrolyzer according to claim 1, characterized in that: The cubic perovskite-type B-site high-entropy oxide is formed by reducing a scheelite-structured high-entropy oxide Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 M 0.2 )O 4 .

3. The cathode material for a solid oxide fuel electrolyzer according to claim 1, characterized in that: the size of the multi - alloy FeM nanoparticles is between 50 and 150 nm.

4. A method for preparing the cathode material for a solid oxide fuel electrolyzer according to any one of claims 1 - 3, characterized in that: comprises the following steps: S1. Preparation of a precursor of a high-entropy oxide Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 M 0.2 )O 4 with a tetragonal scheelite structure; S2: Mix and grind the precursor and the binder to prepare a slurry, coat it on the surface of the electrolyte and dry it to prepare a cell; S3: Apply a certain current to the battery under a certain operating temperature and in a reducing atmosphere for electrochemically polarized reduction to in-situ form a cubic perovskite-structured high-entropy oxide Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 M 0.2 )O 3-δ .

5. The preparation method according to claim 4, characterized in that: In step S1, the sol-gel laser treatment technique is used to prepare the perovskite-structured high-entropy oxide Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 M 0.2 )O 4 precursor.

6. The preparation method according to claim 5, characterized in that: In step S1, prepare a scheelite-structured high-entropy oxide Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 M 0.2 )O 4 The specific operation of the precursor is as follows: S11: Dissolve a certain amount of citric acid in an ethanol - aqueous solution, and then dissolve the Sr source, Fe source, V source, Mo source, Ti source, and M source according to the stoichiometric ratio. After all the above metal sources are completely dissolved, heat and stir until clear and heat to obtain a gel; S12: Laser-treat the gel to obtain a scheelite-structured high-entropy oxide precursor Sr(Fe 0.2 V 0.2 Mo 0.2 Ti 0.2 M 0.2 )O 4 .

7. The preparation method according to claim 6, characterized in that: In step S11, the molar ratio of citric acid to metal ions is (1.5 - 2):1; in step S12, the gel is placed in a quartz glass groove for laser processing; the laser power for the laser processing is 10 - 15 W, the scanning speed is 30 - 40 mm·s -1 , the frequency is 10 - 20 kHz, and the processing time is 10 - 20 min.

8. The preparation method according to claim 4, characterized in that: In step S2, the binder is terpineol containing 7.5 - 10 wt.% ethyl cellulose; the mass ratio of the precursor to the binder is 1:(1.5 - 2).

9. The preparation method according to claim 4, characterized in that: In step S3, the working temperature is 800 - 900 °C, the reducing atmosphere is pure hydrogen, and the applied current for electrochemical polarization is 20 - 50 mA·cm -2 , and the polarization time is 60 - 180 min.

10. An application of the cathode material for a solid oxide fuel electrolyzer according to any one of claims 1 - 3, characterized in that: For a solid oxide fuel cell cathode, for CO 2 electrolysis or CO 2 -H 2 O co-electrolysis.

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