Preparation method and application of high-entropy perovskite-based heterostructure catalyst

Abstract

The present application relates to the technical field of catalyst, in particular to a preparation method of high-entropy perovskite-based heterostructure catalyst and application thereof.The high-entropy perovskite-based heterostructure catalyst provided by the present application is formed by high-entropy perovskite type La(FeCoNiCrMg)O3(core) and amorphous NiFeOOH(shell) to form a heterostructure, promote charge transfer and accelerate the catalytic kinetics of oxygen evolution reaction.Amorphous NiFeOOH has a cross super-thin nanosheet structure, which can improve the morphology of the core, significantly increase the specific surface area of the catalyst, and also provide more active sites, thereby improving the adsorption energy of the oxygen evolution reaction intermediate and the electrical conductivity, and greatly improving the oxygen evolution catalytic performance of the catalyst.The La(FeCoNiCrMg)O3@NiFeOOH catalyst provided by the present application has excellent oxygen evolution catalytic performance and catalytic stability, and has good application prospect as an oxygen evolution catalyst.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a method for preparing a high-entropy perovskite-based heterostructure catalyst and its application. Background Technology

[0002] Hydrogen energy, with its high energy density and zero carbon content, is considered a decisive factor in the transition to carbon-neutral and sustainable systems. Electrocatalytic water splitting, as a green, environmentally friendly, and sustainable hydrogen production method, is widely regarded as one of the most promising technologies for hydrogen production, a current hot topic in scientific research, and a core issue to be addressed in green energy H2 production research projects. Electrocatalytic water splitting consists of the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode. Due to the complex four-electron transfer mechanism of OER, its kinetics are relatively slow, making OER a bottleneck for water splitting efficiency. To date, iridium-based and ruthenium-based oxides remain the most advanced OER catalysts, but their high cost and scarcity hinder their large-scale industrial application. Therefore, exploring efficient and low-cost OER electrocatalysts is key to improving the efficiency of hydrogen production through water electrolysis.

[0003] High-entropy perovskite oxides (HEPOs) combine the advantages of high intrinsic activity of perovskites, tunable structure / composition, and the inherent synergistic and high-entropy effects between different active metals in high-entropy materials, and have been proven in recent years to provide a new platform for screening highly efficient electrocatalysts. However, conventionally morphological HEPOs suffer from low OER catalytic activity due to their small surface area, limited number of exposed active sites, and poor intermediate absorption energy. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for preparing a high-entropy perovskite-based heterostructure catalyst and its application. The high-entropy perovskite-based heterostructure catalyst provided by this invention has excellent oxygen evolution reaction (OER) catalytic activity and catalytic stability.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a high-entropy perovskite-based heterostructure catalyst with a core-shell heterostructure. The core of the core-shell heterostructure is a high-entropy perovskite-type La(FeCoNiCrMg)O3, and the shell of the core-shell heterostructure is an amorphous NiFeOOH with an intersecting ultrathin nanosheet structure.

[0007] Preferably, the molar ratio of La, Fe, Co, Ni, Cr and Mg in the high-entropy perovskite type La(FeCoNiCrMg)O3 is 0.9-1:0.15-0.25:0.15-0.25:0.15-0.25:0.15-0.25:0.15-0.25.

[0008] Preferably, the particle size of the core is 50-100 nm.

[0009] Preferably, the thickness of the shell is 2 to 10 nm.

[0010] This invention provides a method for preparing the high-entropy perovskite-based heterostructure catalyst described above, comprising the following steps:

[0011] Provides high-entropy perovskite-type La(FeCoNiCrMg)O3;

[0012] The high-entropy perovskite-type La(FeCoNiCrMg)O3 was mixed with a water-soluble nickel source, a water-soluble ferrous source, and water, and then subjected to chemical bath deposition to obtain a high-entropy perovskite-based heterostructure catalyst.

[0013] Preferably, the high-entropy perovskite type La(FeCoNiCrMg)O3 is prepared by solid-state reaction, sol-gel method, co-precipitation method or electrospinning method.

[0014] Preferably, the co-precipitation method includes the following steps:

[0015] A water-soluble lanthanum source, a water-soluble iron source, a water-soluble cobalt source, a water-soluble nickel source, a water-soluble chromium source, and a water-soluble magnesium source are dissolved in water to obtain a mixed solution of metal ions.

[0016] The metal ion mixture and the aqueous precipitant solution were mixed and co-precipitated to obtain a high-entropy perovskite precursor.

[0017] The high-entropy perovskite precursor was calcined to obtain high-entropy perovskite-type La(FeCoNiCrMg)O3.

[0018] Preferably, the amount of the water-soluble nickel source is calculated in terms of nickel element, the amount of the water-soluble ferrous source is calculated in terms of iron element, the total amount of the water-soluble nickel source and the water-soluble iron source is in a molar ratio of 1 to 5:1 to the high-entropy perovskite type La(FeCoNiCrMg)O3, and the molar ratio of the water-soluble nickel source to the water-soluble ferrous source is 1:1 to 3.

[0019] Preferably, the chemical bath deposition temperature is 60–100°C, and the time is 1–4 hours.

[0020] This invention provides the application of the high-entropy perovskite-based heterostructure catalyst described in the above technical solution or the high-entropy perovskite-based heterostructure catalyst prepared by the above technical solution as an oxygen evolution catalyst.

[0021] This invention provides a high-entropy perovskite-based heterostructure catalyst (denoted as La(FeCoNiCrMg)O3@NiFeOOH) with a core-shell heterostructure. The core of the core-shell heterostructure is high-entropy perovskite-type La(FeCoNiCrMg)O3, and the shell is amorphous NiFeOOH with an intersecting ultrathin nanosheet structure. In the high-entropy perovskite-based heterostructure catalyst provided by this invention, the high-entropy perovskite-type La(FeCoNiCrMg)O3 and amorphous NiFeOOH form a heterostructure, promoting charge transfer and accelerating the catalytic kinetics of the oxygen evolution reaction (OER). The amorphous NiFeOOH, with its intersecting ultrathin nanosheet structure, improves the morphology of the high-entropy perovskite-type La(FeCoNiCrMg)O3, significantly increasing the specific surface area of ​​the catalyst. It also provides more active sites, thereby increasing the adsorption energy of the OER intermediates and improving the conductivity, greatly enhancing the OER catalytic performance of the catalyst. The La(FeCoNiCrMg)O3@NiFeOOH catalyst provided by this invention has excellent oxygen evolution catalytic performance and catalytic stability, and has good application prospects as an oxygen evolution catalyst.

[0022] The preparation method provided by this invention is simple to operate, has a simple process, low production cost, is green and environmentally friendly, and is suitable for industrial production. Attached Figure Description

[0023] Figure 1 XRD patterns of La(FeCoNiCrMg)O3@NiFeOOH prepared in Examples 1-3, and La(FeCoNiCrMg)O3 prepared in Example 4 and Comparative Example 1;

[0024] Figure 2 Nitrogen adsorption-desorption isotherms of La(FeCoNiCrMg)O3@NiFeOOH prepared in Example 1 and La(FeCoNiCrMg)O3 prepared in Example 4;

[0025] Figure 3 SEM images of La(FeCoNiCrMg)O3@NiFeOOH prepared in Example 1 and La(FeCoNiCrMg)O3 prepared in Example 4;

[0026] Figure 4 TEM images of La(FeCoNiCrMg)O3@NiFeOOH prepared in Example 1 and La(FeCoNiCrMg)O3 prepared in Example 4;

[0027] Figure 5 The graph shows the electrocatalytic oxygen evolution performance of La(FeCoNiCrMg)O3 prepared in Examples 4-8 and Comparative Example 1.

[0028] Figure 6 The electrocatalytic oxygen evolution performance of La(FeCoNiCrMg)O3@NiFeOOH prepared in Examples 1-3 and La(FeCoNiCrMg)O3 prepared in Example 4 are shown in the figure.

[0029] Figure 7 The image shows the electrocatalytic oxygen evolution stability of La(FeCoNiCrMg)O3@NiFeOOH prepared in Example 1. Detailed Implementation

[0030] This invention provides a high-entropy perovskite-based heterostructure catalyst with a core-shell structure. The core is a high-entropy perovskite-type La(FeCoNiCrMg)O3, and the shell is an amorphous NiFeOOH. In this invention, the molar ratio of La, Fe, Co, Ni, Cr, and Mg in the high-entropy perovskite-type La(FeCoNiCrMg)O3 is preferably 0.9–1:0.15–0.25:0.15–0.25:0.15–0.25:0.15–0.25, more preferably 1:0.2:0.2:0.2:0.2:0.2. In this invention, the particle size of the core is preferably 50–100 nm, more preferably 60–80 nm. In this invention, the thickness of the shell is preferably 2–10 nm, more preferably 4–8 nm. In this invention, the microstructure of the high-entropy perovskite-based heterostructure catalyst is preferably lamellar.

[0031] This invention provides a method for preparing the high-entropy perovskite-based heterostructure catalyst described above, comprising the following steps:

[0032] Provides high-entropy perovskite-type La(FeCoNiCrMg)O3;

[0033] The high-entropy perovskite-type La(FeCoNiCrMg)O3 was mixed with a water-soluble nickel source, a water-soluble ferrous source, and water, and then subjected to chemical bath deposition to obtain a high-entropy perovskite-based heterostructure catalyst.

[0034] Unless otherwise specified, all raw materials used in this invention are commercially available products.

[0035] This invention provides high-entropy perovskite type La(FeCoNiCrMg)O3.

[0036] In this invention, the high-entropy perovskite La(FeCoNiCrMg)O3 is preferably prepared by solid-state reaction, sol-gel method, co-precipitation method, or electrospinning method. This invention does not have specific limitations on the solid-state reaction method, sol-gel method, co-precipitation method, and electrospinning method, as long as high-entropy perovskite La(FeCoNiCrMg)O3 can be obtained. In a specific embodiment of this invention, the co-precipitation method is used to prepare high-entropy perovskite La(FeCoNiCrMg)O3.

[0037] In this invention, the coprecipitation method preferably includes the following steps: dissolving a water-soluble lanthanum source, a water-soluble iron source, a water-soluble cobalt source, a water-soluble nickel source, a water-soluble chromium source, and a water-soluble magnesium source in water to obtain a metal ion mixture; mixing the metal ion mixture with an aqueous precipitant solution to perform coprecipitation to obtain a high-entropy perovskite precursor; and calcining the high-entropy perovskite precursor to obtain high-entropy perovskite-type La(FeCoNiCrMg)O3.

[0038] This invention dissolves a water-soluble lanthanum source, a water-soluble iron source, a water-soluble cobalt source, a water-soluble nickel source, a water-soluble chromium source, and a water-soluble magnesium source in water to obtain a mixed solution of metal ions. This invention does not specifically limit the water-soluble iron source, water-soluble cobalt source, water-soluble nickel source, water-soluble chromium source, and water-soluble magnesium source; any water-soluble lanthanum source, water-soluble iron source, water-soluble cobalt source, water-soluble nickel source, water-soluble chromium source, and water-soluble magnesium source well-known to those skilled in the art can be used. Specifically, the water-soluble iron source preferably includes one or more of ferric nitrate, ferric sulfate, and ferric acetate; the water-soluble cobalt source preferably includes one or more of cobalt nitrate, cobalt sulfate, and cobalt acetate; the water-soluble nickel source preferably includes one or more of nickel nitrate, nickel sulfate, and nickel acetate; the water-soluble chromium source preferably includes one or more of chromium nitrate, chromium sulfate, and chromium acetate; and the water-soluble magnesium source preferably includes one or more of magnesium nitrate, magnesium sulfate, and magnesium acetate. In this invention, the molar ratio of lanthanum, iron, cobalt, nickel, chromium, and magnesium in the metal ion mixture is preferably 0.9–1:0.15–0.25:0.15–0.25:0.15–0.25:0.15–0.25:0.15–0.25, more preferably 1:0.2:0.2:0.2:0.2:0.2. In this invention, the total concentration of metal ions in the metal ion mixture is preferably 0.2–0.3 mol / L, more preferably 0.25 mol / L; the water is preferably deionized water.

[0039] After obtaining the metal ion mixture, the present invention mixes the metal ion mixture with an aqueous precipitant solution and performs co-precipitation to obtain a high-entropy perovskite precursor.

[0040] In this invention, the precipitant in the aqueous precipitant solution is preferably a hydroxide, more preferably potassium hydroxide and / or sodium hydroxide; the concentration of the aqueous precipitant solution is preferably 0.5-0.6 mol / L, more preferably 0.55 mol / L. In this invention, the aqueous precipitant solution is preferably obtained by dissolving the precipitant in water; the water is preferably deionized water. In this invention, the molar ratio of the total amount of metal ions in the metal ion mixture to the precipitant in the aqueous precipitant solution is preferably 1:2-4, more preferably 1:1-2, and even more preferably 1:1-1.5. This invention, by controlling the ratio of the total amount of metal ions in the metal ion mixture to the concentration and dosage of the precipitant, is beneficial for increasing the nucleation rate, easily obtaining higher entropy perovskite-type La(FeCoNiCrMg)O3 with smaller particle size, and thus improving the catalytic activity of the oxygen evolution reaction of the catalyst.

[0041] In this invention, the mixing is preferably performed by simultaneously adding the metal ion mixture and the precipitant aqueous solution; the mixing is preferably performed by stirring, and this invention does not have a particular limitation on the stirring speed, as long as the raw materials are mixed evenly. Compared with other feeding methods (forward addition, reverse addition), the simultaneous addition method of this invention is beneficial to more uniform mixing of metal ions and precipitant, avoiding excessive local concentration that leads to the formation of large particles, thereby obtaining high-entropy perovskite type La(FeCoNiCrMg)O3 with smaller particle size, and thus improving the catalytic activity of the catalyst in the oxygen evolution reaction.

[0042] In this invention, the temperature of the co-precipitation is preferably 20-50°C, more preferably room temperature (25°C); the time of the co-precipitation is preferably 3-6 hours, more preferably 3-5 hours, and even more preferably 4-5 hours; the co-precipitation is preferably carried out under stirring conditions.

[0043] After the coprecipitation is completed, the present invention preferably further includes solid-liquid separation of the obtained coprecipitation system, wherein the obtained solid product is sequentially washed with water, dried, and ground to obtain a high-entropy perovskite precursor (powder). The present invention does not have a specific limitation on the solid-liquid separation; any solid-liquid separation method well known to those skilled in the art can be used, such as filtration, vacuum filtration, or centrifugation. In the present invention, the number of water washings is preferably 2 to 4 times, more preferably 3 times. In the present invention, the drying temperature is preferably 60 to 100°C, more preferably 60 to 80°C; the present invention does not have a specific limitation on the drying time, drying to constant weight is sufficient. In the present invention, the particle size of the high-entropy perovskite precursor is preferably 50 to 100 nm, more preferably 60 to 80 nm.

[0044] After obtaining the high-entropy perovskite precursor, the present invention calcines the high-entropy perovskite precursor to obtain high-entropy perovskite type La(FeCoNiCrMg)O3.

[0045] In this invention, the calcination temperature is preferably 700–1000℃, more preferably 700–900℃, and even more preferably 800–900℃; the holding time for calcination is preferably 3–6 h, more preferably 3–5 h, and even more preferably 4–5 h; the heating rate from room temperature to the calcination temperature is preferably 2–5℃ / min, more preferably 2–5℃ / min, and even more preferably 3–4℃ / min; the calcination atmosphere is preferably air; and the calcination is preferably carried out in a muffle furnace. If the calcination temperature is too low or the holding time is too short, the formation of high-entropy perovskite La(FeCoNiCrMg)O3 will be incomplete, resulting in lower crystallinity; if the calcination temperature is too high or the holding time is too long, agglomeration will easily occur, leading to an increase in the particle size of high-entropy perovskite La(FeCoNiCrMg)O3. This invention, by controlling the calcination temperature and calcination time, is beneficial for obtaining high-entropy perovskite La(FeCoNiCrMg)O3 with smaller particle size, thereby improving the catalytic activity of the oxygen evolution reaction catalyst.

[0046] After the calcination is completed, the present invention preferably further includes cooling the obtained calcined material to room temperature to obtain high-entropy perovskite type La(FeCoNiCrMg)O3. In the present invention, the cooling rate is preferably 2-5 °C / min, more preferably 2-5 °C / min, and even more preferably 3-4 °C / min.

[0047] After obtaining high-entropy perovskite-type La(FeCoNiCrMg)O3, the present invention mixes the high-entropy perovskite-type La(FeCoNiCrMg)O3 with a water-soluble nickel source, a water-soluble ferrous source and water, and performs chemical bath deposition to obtain a high-entropy perovskite-based heterostructure catalyst.

[0048] In this invention, the water-soluble nickel source preferably includes nickel nitrate and / or nickel sulfate; the water-soluble ferrous source preferably includes ferrous nitrate and / or ferrous sulfate.

[0049] In this invention, the amount of the water-soluble nickel source is calculated as nickel element, the amount of the water-soluble iron source is calculated as iron element, and the molar ratio of the total amount of the water-soluble nickel source and the water-soluble iron source to the high-entropy perovskite type La(FeCoNiCrMg)O3 is preferably 1 to 5:1, more preferably 2 to 4:1, and even more preferably 3:1; the molar ratio of the water-soluble nickel source to the water-soluble iron source is preferably 1:1 to 3, more preferably 1:1 to 3, and even more preferably 1:1 to 2.

[0050] In this invention, the preferred mixing sequence is to disperse the high-entropy perovskite-type La(FeCoNiCrMg)O3 in water, and then mix the resulting nuclear aqueous dispersion, water-soluble nickel source, and water-soluble iron source; the water is preferably deionized water; the dispersion is preferably ultrasonic dispersion, and the ultrasonic dispersion temperature is preferably 20-40°C, more preferably room temperature; the time is preferably 20-60 min, more preferably 30-40 min; the mixing is preferably stirring, and this invention does not have any special limitation on the stirring speed and time, as long as the raw materials are mixed evenly.

[0051] In this invention, the temperature of the chemical bath deposition is preferably 60-100°C, more preferably 70-90°C, and even more preferably 80°C; the time of the chemical bath deposition is preferably 1-4 hours, more preferably 1-3 hours, and even more preferably 1-2 hours.

[0052] After the chemical bath deposition is completed, the present invention preferably further includes solid-liquid separation of the obtained chemical bath deposition system, washing the obtained solid product with water and drying it to obtain a high-entropy perovskite-based heterostructure catalyst. The present invention does not have a particular limitation on the solid-liquid separation; any solid-liquid separation method well known to those skilled in the art can be used, such as filtration, vacuum filtration, or centrifugation. In the present invention, the number of water washings is preferably 2 to 4 times, more preferably 3 times. In the present invention, the drying temperature is preferably 60 to 100°C, more preferably 60 to 80°C; the present invention does not have a particular limitation on the drying time, drying to constant weight is sufficient.

[0053] This invention provides the application of the high-entropy perovskite-based heterostructure catalyst described in the above-described technical solutions, or the high-entropy perovskite-based heterostructure catalyst prepared by the above-described technical solutions, as an oxygen evolution catalyst. In the high-entropy perovskite-based heterostructure catalyst provided by this invention, high-entropy perovskite-type La(FeCoNiCrMg)O3 and amorphous NiFeOOH form a heterostructure, promoting charge transfer and accelerating the catalytic kinetics of the oxygen evolution reaction. The amorphous NiFeOOH has a cross-linked ultrathin nanosheet structure, which can improve the morphology of high-entropy perovskite-type La(FeCoNiCrMg)O3, significantly increasing the specific surface area of ​​the catalyst, and also providing more active sites, thereby increasing the adsorption energy of the oxygen evolution reaction intermediates and improving the conductivity, greatly enhancing the oxygen evolution catalytic performance of the catalyst. The La(FeCoNiCrMg)O3@NiFeOOH catalyst provided by this invention has excellent oxygen evolution catalytic performance and catalytic stability, and has good application prospects as an oxygen evolution catalyst.

[0054] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0055] In the following examples, the purity of lanthanum nitrate, ferric nitrate, cobalt nitrate, nickel nitrate, chromium nitrate, and magnesium nitrate is ≥99%.

[0056] Example 1

[0057] (1) Dissolve 2.598g lanthanum nitrate, 0.485g ferric nitrate, 0.349g cobalt nitrate, 0.349g nickel nitrate, 0.48g chromium nitrate and 0.308g magnesium nitrate in 60mL of deionized water to obtain a metal ion mixture; dissolve 2.722g potassium hydroxide in 90mL of deionized water to obtain a potassium hydroxide solution; add the metal ion mixture and potassium hydroxide solution simultaneously and slowly into a beaker, stir magnetically for 4.5h, filter, wash the obtained precipitate with water 3 times, dry it in an 80℃ oven for 12h, pour it into an agate mortar and grind it to obtain high-entropy perovskite precursor powder;

[0058] (2) The high-entropy perovskite precursor powder was placed in an alumina crucible and heated to 900°C in a muffle furnace at a heating rate of 5°C / min. The mixture was calcined for 3 hours and then cooled to room temperature at a rate of 2°C / min to obtain high-entropy perovskite type La(FeCoNiCrMg)O3 powder (denoted as La(FeCoNiCrMg)O3).

[0059] (3) Add 0.2g of the high-entropy perovskite-type La(FeCoNiCrMg)O3 powder to 46mL of deionized water, ultrasonically disperse at room temperature for 30min, add 0.2g of nickel nitrate and 0.194g of ferrous sulfate, magnetically stir in an oil bath at 80℃ for 1h, filter, wash the obtained solid product with water 3 times, and dry in an oven at 80℃ for 12h to obtain the high-entropy perovskite-based heterostructure catalyst (denoted as La(FeCoNiCrMg)O3@NiFeOOH).

[0060] Example 2

[0061] The high-entropy perovskite-based heterostructure catalyst was prepared according to the method of Example 1. The only difference from Example 1 is that in step (3), the ultrasonic dispersion time is 30 min, the amount of nickel nitrate is 0.133 g, and the amount of ferrous sulfate is 0.127 g.

[0062] Example 3

[0063] The high-entropy perovskite-based heterostructure catalyst was prepared according to the method of Example 1. The only difference from Example 1 is that in step (3), the amount of high-entropy perovskite La(FeCoNiCrMg)O3 powder is 0.1g, the ultrasonic dispersion time is 30min, the amount of nickel nitrate is 0.133g, and the amount of ferrous sulfate is 0.127g.

[0064] Example 4

[0065] La(FeCoNiCrMg)O3 was prepared according to the method in Example 1.

[0066] Example 5

[0067] La(FeCoNiCrMg)O3 was prepared according to the method of Example 1. The only difference from Example 1 is that the calcination temperature in step (2) is 800℃.

[0068] Example 6

[0069] La(FeCoNiCrMg)O3 was prepared according to the method of Example 1. The only difference from Example 1 is that in step (2), the amount of potassium hydroxide used is 1.361g.

[0070] Example 7

[0071] La(FeCoNiCrMg)O3 was prepared according to the method of Example 1. The only difference from Example 1 is that the calcination time in step (2) is 5 h.

[0072] Example 8

[0073] La(FeCoNiCrMg)O3 was prepared according to the method of Example 1. The only difference from Example 1 is that the calcination temperature in step (2) is 1000℃.

[0074] Comparative Example 1

[0075] La(FeCoNiCrMg)O3 was prepared according to the method of Example 1. The only difference from Example 1 is that in step (1), the potassium hydroxide solution was slowly added to the metal ion mixture (i.e., mixed by positive addition).

[0076] Figure 1The figures show the XRD patterns of La(FeCoNiCrMg)O3@NiFeOOH prepared in Examples 1-3, and La(FeCoNiCrMg)O3 prepared in Example 4 and Comparative Example 1. As can be seen from the figures, both La(FeCoNiCrMg)O3 and La(FeCoNiCrMg)O3@NiFeOOH are pure-phase perovskite structures, and the NiFeOOH in La(FeCoNiCrMg)O3@NiFeOOH is in an amorphous state.

[0077] Figure 2 The nitrogen adsorption-desorption isotherms of La(FeCoNiCrMg)O3@NiFeOOH prepared in Example 1 and La(FeCoNiCrMg)O3 prepared in Example 4 are shown in the figure. As can be seen from the figure, La(FeCoNiCrMg)O3@NiFeOOH exhibits a typical type IV adsorption isotherm, possesses an H3-type hysteresis loop, is predominantly mesoporous, and has a specific surface area of ​​90.4 m². 2 / g; while the specific surface area of ​​La(FeCoNiCrMg)O3 is only 13.4m². 2 / g. This indicates that the construction of the heterostructure in the high-entropy perovskite-based heterostructure catalyst prepared in this invention increases the specific surface area.

[0078] Figure 3 SEM images of La(FeCoNiCrMg)O3@NiFeOOH prepared in Example 1 and La(FeCoNiCrMg)O3 prepared in Example 4 are shown. As can be seen from the images, La(FeCoNiCrMg)O3 consists of interconnected particles of approximately 50–100 nm in size, while La(FeCoNiCrMg)O3@NiFeOOH has a cross-laminated ultrathin nanosheet structure with a smooth surface and open regions between the nanosheets.

[0079] Figure 4 TEM images show La(FeCoNiCrMg)O3@NiFeOOH prepared in Example 1 and La(FeCoNiCrMg)O3 prepared in Example 4. As can be seen from the images, this invention successfully prepared a catalyst with a heterostructure, La(FeCoNiCrMg)O3@NiFeOOH, in which perovskite-type La(FeCoNiCrMg)O3 forms the core and amorphous NiFeOOH forms the shell.

[0080] Figure 5The graphs show the electrocatalytic oxygen evolution reaction (OER) performance of La(FeCoNiCrMg)O3 prepared in Examples 4-8 and Comparative Example 1. As can be seen from the graphs, the overpotentials of La(FeCoNiCrMg)O3 prepared in Examples 4-8 and Comparative Example 1 are 392 mV, 410 mV, 425 mV, 431 mV, 438 mV, and 427 mV, respectively. This indicates that controlling the ratio of the total amount of metal elements in the metal ion mixture to the amount of precipitant, the feeding method, the calcination temperature, and the calcination time can improve the OER catalytic performance of La(FeCoNiCrMg)O3, thereby enhancing the OER catalytic performance of La(FeCoNiCrMg)O3@NiFeOOH.

[0081] Figure 6 The graphs show the electrocatalytic oxygen evolution performance of La(FeCoNiCrMg)O3@NiFeOOH prepared in Examples 1-3 and La(FeCoNiCrMg)O3 prepared in Example 4. As can be seen from the graphs, the overpotentials of La(FeCoNiCrMg)O3@NiFeOOH prepared in Examples 1-3 are 262 mV, 275 mV, and 295 mV, respectively, while the overpotential of La(FeCoNiCrMg)O3 prepared in Example 4 is 392 mV. The overpotentials of La(FeCoNiCrMg)O3@NiFeOOH are all lower than those of La(FeCoNiCrMg)O3, with Example 1 showing the lowest overpotential. This indicates that the construction of the heterostructure significantly improves the catalytic performance of the La(FeCoNiCrMg)O3@NiFeOOH catalyst compared to that of the single perovskite-type La(FeCoNiCrMg)O3.

[0082] Figure 7 The figure shows the electrocatalytic oxygen evolution stability of La(FeCoNiCrMg)O3@NiFeOOH prepared in Example 1. As can be seen from the figure, after 500 cycles, the overpotential of La(FeCoNiCrMg)O3@NiFeOOH prepared in this invention only increases by 14 mV, indicating that La(FeCoNiCrMg)O3@NiFeOOH prepared in this invention has excellent catalytic stability.

[0083] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-entropy perovskite-based heterostructure catalyst having a core-shell heterostructure, wherein the core of the core-shell heterostructure is a high-entropy perovskite-type La(FeCoNiCrMg)O3, and the shell of the core-shell heterostructure is an amorphous NiFeOOH with an intersecting ultrathin nanosheet structure; the thickness of the shell is 2~10 nm; The molar ratio of La, Fe, Co, Ni, Cr and Mg in the high-entropy perovskite type La(FeCoNiCrMg)O3 is 0.9~1:0.15~0.25:0.15~0.25:0.15~0.25:0.15~0.25:0.15~0.25; The particle size of the nucleus is 50~100nm.

2. The preparation method of the high-entropy perovskite-based heterostructure catalyst according to claim 1, comprising the following steps: Provides high-entropy perovskite-type La(FeCoNiCrMg)O3; The high-entropy perovskite-type La(FeCoNiCrMg)O3 was mixed with a water-soluble nickel source, a water-soluble ferrous source and water, and then subjected to chemical bath deposition to obtain a high-entropy perovskite-based heterostructure catalyst. The high-entropy perovskite-type La(FeCoNiCrMg)O3 was prepared by a co-precipitation method; the co-precipitation method includes the following steps: A water-soluble lanthanum source, a water-soluble iron source, a water-soluble cobalt source, a water-soluble nickel source, a water-soluble chromium source, and a water-soluble magnesium source are dissolved in water to obtain a mixed solution of metal ions. The metal ion mixture and the aqueous precipitant solution were mixed in a parallel manner to co-precipitate and obtain a high-entropy perovskite precursor. The high-entropy perovskite precursor was calcined to obtain high-entropy perovskite-type La(FeCoNiCrMg)O3.

3. The preparation method according to claim 2, characterized in that, The amount of the water-soluble nickel source is calculated in terms of nickel element, the amount of the water-soluble ferrous source is calculated in terms of iron element, the total amount of the water-soluble nickel source and the water-soluble iron source is in a molar ratio of 1 to 5:1 to the high-entropy perovskite type La(FeCoNiCrMg)O3, and the molar ratio of the water-soluble nickel source to the water-soluble ferrous source is 1:1 to 3.

4. The preparation method according to claim 2 or 3, characterized in that, The chemical bath deposition temperature is 60~100℃, and the time is 1~4h.

5. The application of the high-entropy perovskite-based heterostructure catalyst of claim 1 or the high-entropy perovskite-based heterostructure catalyst prepared by any one of claims 2 to 4 as an oxygen evolution catalyst.

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