High-entropy perovskite material, preparation method and application thereof

Abstract

The application relates to a high-entropy perovskite material and a preparation method and application thereof, the chemical formula of the high-entropy perovskite material is AB03, wherein the A-site element is a La element, and the B-site element is selected from 5-10 kinds of transition metal elements; the high-entropy perovskite material has a two-dimensional Turing structure, nano-particles are cross-linked and arranged, and there are gaps between the particles. Compared with the prior art, the two-dimensional Turing structure high-entropy perovskite material has unique morphology and components, excellent electrocatalytic water decomposition hydrogen production performance, and fluctuation power adaptability of clean energy such as wind energy and solar energy, and has a wide industrial application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-entropy catalysts, in particular to a high-entropy perovskite material and a preparation method and application thereof. BACKGROUND

[0002] Due to zero carbon emission and high energy density, hydrogen is the most promising clean energy to replace traditional fuels. Therefore, producing green hydrogen through electrocatalytic water splitting is an effective way to achieve the carbon neutralization goal. The anode oxygen evolution reaction (OER) is an important half-reaction in electrocatalytic water splitting. However, due to the slow kinetics of the 4-electron transfer process of the OER reaction, it has become the main reason for limiting the overall efficiency of the electrocatalytic water splitting system. Therefore, developing an OER catalyst with high activity and high stability is the main way to reduce the consumption of the electrolytic water system and achieve efficient hydrogen production.

[0003] High-entropy oxide (HEOs) refers to an oxide material formed by combining five or more elements. Due to the strong interaction between multiple metal elements, HEOs usually exhibit a flexible and adjustable metal site coordination environment and oxidation state, which greatly optimizes the adsorption of OER intermediates, thereby enhancing the OER catalytic activity. However, in the actual industrial electrocatalytic water splitting system, the frequent start-stop of equipment, the reduction effect of reverse current and the corrosion of strong alkaline electrolyte all pose new challenges to the development and design of catalysts. Therefore, it is necessary to provide an OER catalyst that can effectively enhance the adaptability and stability under fluctuating power while ensuring OER activity. SUMMARY

[0004] The purpose of the present application is to provide a high-entropy perovskite material and a preparation method and application thereof, which exhibit high OER activity, power fluctuation adaptability and reverse current resistance.

[0005] The purpose of the present application can be achieved by the following technical solution: a high-entropy perovskite material, the chemical formula of which is AB03, wherein the A-site element is La element, and the B-site element is selected from 5-10 kinds of transition metal elements;

[0006] The high-entropy perovskite material has a two-dimensional Turing structure, and the nanoparticles are arranged in cross-linking mode with gaps between the nanoparticles.

[0007] Preferably, the B-site element is selected from five or more of Mn, Fe, Co, Ni, Cu, Zn, Cr, Mo, W and V.

[0008] Further preferably, the B-site element is selected from five of Mn, Fe, Co, Ni, Cu, Zn, Cr, Mo, W and V.

[0009] More preferably, the B-site element is Mn, Fe, Co, Ni, Cu.

[0010] Preferably, the molar ratio of each transition metal element in the B-site is (1.1-0.9):1.

[0011] Further preferably, the molar ratio of each transition metal element in the B-site is 1:1.

[0012] Preferably, the molar ratio of the La element to the total amount of B-site transition metal elements is (1.1-0.9):1.

[0013] Further preferably, the molar ratio of the La element to the total amount of B-site transition metal elements is 1:1.

[0014] Preferably, the chemical formula of the high-entropy perovskite material is La(Mn 0.2 Fe 0.2 Co 0.2 Ni 0.2 Cu 0.2 )O3.

[0015] Preferably, the high-entropy perovskite material has a lateral size of 5-10 μm and a thickness of 70-100 nm.

[0016] Preferably, the high-entropy perovskite material has a composition unit of coral-like particles.

[0017] Further preferably, the coral-like particles are cross-linked at the head and tail and regularly distributed in a plane in a periodic manner, forming a porous network structure.

[0018] Further preferably, the coral-like particles have a gap of 20-300 nm.

[0019] More preferably, the coral-like particles have a gap of 20-100 nm.

[0020] Preferably, the high-entropy perovskite material has multiple groups of different crystal faces, and the crystal lattice fringes on both sides of the grain boundary are different.

[0021] A preparation method of the above high-entropy perovskite material, comprising the following steps:

[0022] The metal ion nitrate corresponding to the A-site and B-site elements is added to a chelating agent solution, stirred uniformly, then ammonia water is added and the pH of the solution is adjusted to 9-11, the stirring temperature is increased, and the stirring is continued until a metal organic gel is formed;

[0023] The metal organic gel is dried to form a dry gel, and the dry gel is calcined at an elevated temperature to form the high-entropy perovskite material;

[0024] The temperature rising rate is 8-10 DEG C / min, the temperature is raised to 750-850 DEG C and kept for 2-3h.

[0025] The chelating agent is an organic small molecule containing amino and carboxyl functional groups.

[0026] Preferably, the temperature is raised to 800 DEG C and kept for 2-3h in the temperature rising calcination process.

[0027] Preferably, the metal ion nitrate corresponding to the element at position B is added into the chelating agent solution first, and then the metal ion nitrate corresponding to the element at position A is added into the chelating agent solution.

[0028] Further preferably, the metal ion nitrate corresponding to Mn, Fe, Co, Ni and Cu is added into the chelating agent solution in sequence, and then the metal ion nitrate corresponding to La is added into the chelating agent solution.

[0029] Preferably, the chelating agent is glycine, glycine dipeptide or beta-alanine.

[0030] Further preferably, the chelating agent is glycine.

[0031] Preferably, the molar ratio of the chelating agent to the total amount of metal ions corresponding to the elements at positions A and B is (1-10):1.

[0032] Further preferably, the molar ratio of the chelating agent to the total amount of metal ions corresponding to the elements at positions A and B is (3-5):1.

[0033] In the present application, the material obtained between the molar ratio of (3-5):1 has the best OER activity, and is more conducive to the formation of Turing structure.

[0034] More preferably, the molar ratio of the chelating agent to the total amount of metal ions corresponding to the elements at positions A and B is 4:1.

[0035] Preferably, the chelating agent solution is a chelating agent aqueous solution, and the chelating agent is dispersed uniformly in deionized water to form the chelating agent solution.

[0036] Preferably, the preparation method of the high-entropy perovskite material specifically comprises the following steps:

[0037] The metal ion nitrate corresponding to the elements at positions A and B is added into the chelating agent solution, stirred at 40-50 DEG C for 1-3h, then ammonia is added and the pH of the solution is adjusted to 9-11, and then the stirring temperature is raised to 85-95 DEG C, and the stirring is continued until the metal organic gel is formed;

[0038] The metal organic gel is placed in an oven and dried at 100-120°C to form a dry gel, and the dry gel is placed in a muffle furnace to form a flaky solid after temperature rising and calcination, which is the high-entropy perovskite material.

[0039] A catalyst comprising the high-entropy perovskite material.

[0040] An electrode comprising a conductive substrate and the catalyst loaded on the conductive substrate.

[0041] An electrolytic device comprising the electrode.

[0042] Preferably, the electrolytic device comprises a working electrode, a counter electrode, a separator and an electrolyte, and the working electrode is the electrode.

[0043] A method of assembling the electrolytic device into a three-in-series water-splitting electrolyzer, comprising the following steps:

[0044] The working electrode coated with the catalyst is placed in the anode chamber, the nickel foam is placed in the cathode chamber, the polyphenylene sulfide (PPS) film is clamped between the working electrode and the counter electrode, and three groups of the same electrolyzer are connected in series to form the three-in-series water-splitting electrolyzer.

[0045] A 6M KOH solution is placed in a strong alkali-resistant container, and an electrolyte flow rate controller is used to drive the electrolyte to flow into the cathode chamber and the anode chamber, respectively.

[0046] A method of using the three-in-series water-splitting electrolyzer to perform power fluctuation tests and start-stop tests, comprising the following steps:

[0047] The power fluctuation test is switched at current densities of 10 mA / cm 2 , 100 mA / cm 2 and 250 mA / cm 2 , each for a duration of 100 s, and repeated 100 times.

[0048] The power climb test is switched at current densities of 1 mA / cm 2 and 250 mA / cm 2 , each for a duration of 100 s, and repeated 200 times.

[0049] The start-stop test is switched at current densities of 0 mA / cm 2 and 250 mA / cm 2 , each for a duration of 200 s, and repeated 40 times.

[0050] An application of the high-entropy perovskite material, wherein the high-entropy perovskite material is used as an anode oxygen evolution reaction catalyst for an electrocatalytic water splitting system.

[0051] Preferably, the high-entropy perovskite material is loaded on a conductive substrate as an anode oxygen evolution reaction catalyst to obtain a working electrode, and the working electrode is placed in an anode chamber of an alkaline water splitting electrolyzer (AWE) as an anode for use in an electrocatalytic water splitting system.

[0052] Further preferably, the conductive substrate comprises a nickel foam or a carbon paper.

[0053] More preferably, the nickel foam has a thickness of 1-3 mm.

[0054] Further preferably, the alkaline water splitting electrolyzer comprises an anode chamber, a cathode chamber and a separator, the anode chamber is provided with an anode and an anode electrolyte, the cathode chamber is provided with a cathode and a cathode electrolyte, the separator is used to separate the cathode electrolyte in the cathode chamber and the anode electrolyte in the anode chamber, the anode is the working electrode, and the cathode is a nickel foam.

[0055] More preferably, the flow rate of the cathode electrolyte and the anode electrolyte is 25-35 mL / min.

[0056] More preferably, the cathode electrolyte and the anode electrolyte are KOH solution, NaOH solution, KCl solution or NaCl solution.

[0057] Preferably, the cathode electrolyte and the anode electrolyte are 1-6 M KOH solution.

[0058] More preferably, the separator is a proton exchange membrane or an ion exchange membrane.

[0059] Preferably, the separator is a polyphenylene sulfide (PPS) membrane.

[0060] Further preferably, the internal parts of the alkaline water splitting electrolyzer are made of strong alkali-resistant materials.

[0061] More preferably, the end plate of the alkaline water splitting electrolyzer is made of stainless steel.

[0062] More preferably, the bipolar plate of the alkaline water splitting electrolyzer is made of metal nickel.

[0063] More preferably, the anode chamber and the cathode chamber of the alkaline water splitting electrolyzer are made of polytetrafluoroethylene.

[0064] An application of the above-mentioned high-entropy perovskite material in a simulated industrial electrocatalytic water splitting environment.

[0065] Compared with the prior art, the present application has the following beneficial effects:

[0066] 1.The two-dimensional Turing structure high-entropy perovskite material of the present application can enhance the adsorption of intermediate species after applying an electric potential, and at the same time become more flexible, which helps to enhance the ability of water splitting electrode to adapt to power fluctuations and frequent start-stop.

[0067] 2.The two-dimensional Turing structure high-entropy perovskite material of the present application as an electrocatalytic water splitting catalyst exhibits high OER activity, power fluctuation adaptability and reverse current resistance.

[0068] 3.The two-dimensional Turing structure high-entropy perovskite material of the present application can be used to prepare high-quality OER anode catalyst and three-series water splitting electrolytic cell anode, which has lower overpotential, higher stability and stronger fluctuating power adaptability than conventional nickel foam electrodes.

[0069] 4.The two-dimensional Turing structure high-entropy perovskite material and the assembled electrolytic cell of the present application can operate stably in strong alkali and hot alkali electrolyte conditions, and have high corrosion resistance. On the one hand, the B-site transition metal elements in the perovskite material have good anti-dissolution ability in strong alkali and high potential, and the high-entropy effect enhances this stability. On the other hand, the polyphenylene sulfide separator used in the electrolytic cell can withstand strong alkali and hot alkali, and the internal components of the electrolytic cell are also made of strong alkali-resistant stainless steel, metal nickel or polytetrafluoroethylene material.

[0070] 5.The present application ensures the formation of more uniform perovskite precursor organic gel by adjusting the type of chelating agent, the selection and ratio of A-site metal and B-site metal during catalyst synthesis.

[0071] 6.The present application can ensure that the metal organic gel expands at a more stable rate by coordinating the heating rate and calcination temperature, and at the same time ensure that the CO2 release rate during the combustion of the organic gel is more stable, avoiding the destruction of the two-dimensional morphology caused by too fast expansion or too fast CO2 release.

[0072] 7.The two-dimensional Turing structure high-entropy perovskite catalyst of the present application exhibits more than 220h of stability in a three-series water splitting electrolytic cell (6M KOH electrolyte at 60℃), and maintains high peak potential stability after 40 cycles of start-stop test, and still maintains a response rate of less than 30s after 200 times of 1000 times power surge.

[0073] 8.The present application only needs one kind of chelating agent, has a shorter material synthesis period, is easy to operate, and has high repeatability.

[0074] 9.The two-dimensional Turing structure high-entropy perovskite material of the present application has excellent electrocatalytic water splitting hydrogen production performance and fluctuating power adaptability to clean energy such as wind energy and solar energy due to its unique morphology and composition, and has broad industrial application prospects. BRIEF DESCRIPTION OF DRAWINGS

[0075] Figure 1 are scanning electron microscope images of HEOs-Gly at scales of 5 microns and 1 micron, respectively.

[0076] Figure 2 are side scanning electron microscope images of HEOs-Gly at scales of 5 microns and 1 micron, respectively.

[0077] Figure 3 wherein A is a transmission electron microscope image of a Turing particle of HEOs-Gly at a scale of 100 nm, and B is a high-resolution lattice fringe at a scale of 10 nm.

[0078] Figure 4 wherein A and B are transmission electron microscope images of another Turing particle of HEOs-Gly at a scale of 200 nm, and high-resolution lattice fringes at a scale of 5 nm at different locations.

[0079] Figure 5 is the result of a dissipative electrochemical quartz crystal microbalance (EQCM-D) test of HEOs-Gly. Panel A is the result of the resonance frequency (f) of a quartz crystal chip sensor coated with HEOs-Gly powder collected during a cyclic voltammetry (CV) test. Panel B is the result of the dissipation factor (D) of the quartz crystal chip sensor collected during the CV test.

[0080] Figure 6 is a schematic diagram of a three-in-series water-splitting electrolyzer used in the test of electrocatalytic water splitting.

[0081] Figure 7 is a stability plot of the HEOs-Gly electrode obtained from the test using the three-in-series water-splitting electrolyzer.

[0082] wherein the test duration is 220 h, the test current is 250 mA / cm 2 , the test condition is 60 °C, and the electrolyte is 6 M KOH.

[0083] Figure 8 is a start-stop test plot of the HEOs-Gly electrode obtained from the test using the three-in-series water-splitting electrolyzer.

[0084] wherein the stop current density is 0 mA / cm 2 , the running current density is 250 mA / cm 2 , each time period is 200 s, the test condition is 60 °C, and the electrolyte is 6 M KOH.

[0085] Figure 9is the power step fluctuation test plot of HEOs-Gly electrode using three series water-splitting electrolyzer. The current density is 10 mA / cm 2 , 100 mA / cm 2 and 250 mA / cm 2 , respectively, with 100 s for each period, 60 °C for test condition, and 6 M KOH for electrolyte.

[0086] Figure 10 is the power fluctuation test plot of HEOs-Gly electrode using three series water-splitting electrolyzer. The lowest current density is 1 mA / cm 2 and the highest current density is 250 mA / cm 2 , respectively, with 100 s for each period, 60 °C for test condition, and 6 M KOH for electrolyte.

[0087] Figure 11 is the scanning electron microscope photos of HEOs-Ala with scale of 5 microns and 1 micron.

[0088] Figure 12 is the scanning electron microscope photos of HEOs-Cyc with scale of 5 microns and 1 micron.

[0089] Figure 13 is the scanning electron microscope photos of HEOs-Eth with scale of 5 microns and 1 micron.

[0090] Figure 14 is the scanning electron microscope photos of HEOs-Pla with scale of 5 microns and 1 micron.

[0091] Figure 15 is the comparison of linear voltammetry scan curves of five different catalysts.

[0092] Figure 16 is the scanning electron microscope photos of HEOs-Gly+CA with scale of 5 microns and 1 micron.

[0093] Figure 17 is the scanning electron microscope photos of HEOs-EDTA+CA with scale of 5 microns and 1 micron.

[0094] Figure 18 is the scanning electron microscope photos of HEOs-EDTA+Gly with scale of 5 microns and 1 micron.

[0095] Reference signs: anode end plate 110, anode electrolyte inlet 111, anode pole plate 120, anode pole plate lug 121, anode gas chamber 130, diaphragm 131, cathode gas chamber 132, bipolar plate 140, cathode pole plate 150, cathode pole plate lug 151, cathode end plate 160, cathode electrolyte inlet 161. DETAILED DESCRIPTION

[0096] The application will be described in greater detail with reference to the accompanying drawings and specific embodiments. The embodiments are implemented on the basis of the technical solutions of the application, and detailed implementation modes and specific operation processes are given, but the protection scope of the application is not limited to the following embodiments.

[0097] In the first aspect of the application, a novel two-dimensional Turing structure high-entropy perovskite material is provided, which comprises A-site lanthanum (La) elements and B-site 5-10 transition metal elements.

[0098] In some embodiments of the application, the molar ratio of A-site La elements to all transition metal elements at B-site is between 1.1:1 and 0.9:1, and the most preferred molar ratio is 1:1.

[0099] In some embodiments of the application, the transition metal elements at B-site are Mn, Fe, Co, Ni, Cu, Zn, Cr, Mo, W, and V.

[0100] In some preferred embodiments of the application, the transition metals are Mn, Fe, Co, Ni, and Cu, and the preferred molar ratio of each transition metal element is 1:1.

[0101] In some embodiments of the application, the molar ratio of the chelating agent to all metal ions is between 1:1 and 10:1, and the most preferred molar ratio is 4:1.

[0102] In other embodiments of the application, the chelating agent for metal ions can be selected from glycine, glycine dipeptide, or beta-alanine, and the most preferred chelating agent is glycine.

[0103] In the second aspect of the application, a method for preparing the two-dimensional Turing structure high-entropy perovskite material of the first aspect of the application is provided, which comprises the following steps:

[0104] The chelating agent is added to deionized water to form a chelating agent solution. Metal ion nitrate is added to the above solution in sequence, and stirred at 45°C for 1-3h. Subsequently, ammonia is added and the pH of the solution is adjusted to 9-11, and then the stirring temperature is raised to 85-95°C, and the stirring is continued until the metal organic gel is formed.

[0105] The metal organic gel formed by the above method is placed in an oven and dried at 100-120°C to form a dry gel. The dry gel is then placed in a muffle furnace, and the temperature is raised to 800°C at a rate of 8-10°C / min and maintained at this temperature for 2-3h. The sheet-shaped solid formed after calcination is a two-dimensional Turing structure high-entropy perovskite material.

[0106] In a third aspect of the present application, a catalyst is provided, which comprises the two-dimensional Turing structure high-entropy perovskite material described above.

[0107] In a fourth aspect of the present application, an electrode is provided, which comprises a conductive substrate and the catalyst described above supported on the conductive substrate. The conductive substrate is a nickel foam (1-3mm thick) or carbon paper, and the 1mm thick nickel foam is the preferred substrate.

[0108] In a fifth aspect of the present application, an electrolysis device is provided, which comprises the electrode described above.

[0109] In some embodiments of the present application, the electrolysis device comprises an anode, a cathode, a separator and an electrolyte, and the anode is the electrode described above.

[0110] In some embodiments of the present application, the electrolysis device is an alkaline water splitting electrolyzer (AWE), and the electrolysis flow cell device comprises an anode chamber, a cathode chamber, a separator, an anode chamber electrolyte flow rate controller and a cathode chamber electrolyte flow rate controller. The anode chamber is provided with an anode and an electrolyte, and the anode is the electrode described above. The cathode chamber is provided with a cathode and an electrolyte, and the separator is used to separate the electrolyte in the cathode chamber from the electrolyte in the anode chamber. The anode chamber electrolyte flow rate controller and the cathode chamber electrolyte flow rate controller are used to control the flow rates of the anode electrolyte in the anode chamber and the cathode electrolyte in the cathode chamber, respectively.

[0111] In some embodiments of the present application, the flow rates of the cathode electrolyte and the anode electrolyte are both 30mL / min.

[0112] In some embodiments of the present application, the electrolysis device comprises a working electrode, a counter electrode, a separator and an electrolyte, and the working electrode is the electrode described above. The counter electrode includes but is not limited to a platinum electrode, a nickel foam electrode and a Raney nickel electrode. The electrolyte includes but is not limited to a KOH solution, a NaOH solution, a KCl solution and a NaCl solution. The separator includes but is not limited to a proton exchange membrane and an ion exchange membrane. The most preferred electrolyte is KOH, the most preferred counter electrode is a nickel foam electrode, and the most preferred membrane is a PPS membrane.

[0113] In some embodiments of the present application, the electrolyte is a 1-6M KOH solution.

[0114] In a sixth aspect of the present application, a method for assembling the above electrolytic device into a three-in-series water-splitting electrolyzer and performing electrocatalytic water splitting to produce hydrogen is provided.

[0115] In some embodiments of the present application, the catalyst-coated working electrode is placed in the anode chamber, the foamed nickel is placed in the cathode chamber, and the PPS membrane is sandwiched between the working electrode and the counter electrode. Three groups of the above-mentioned assembled electrolyzers are connected in series, and after being fixed with bolts, a three-in-series water-splitting electrolyzer is obtained.

[0116] In some embodiments of the present application, a 6M KOH solution is placed in a strong alkali-resistant container, and an electrolyte flow rate controller is used to drive the electrolyte to flow into the cathode chamber and the anode chamber, respectively.

[0117] In some embodiments of the present application, the stability test is performed at a current density of 250 mA / cm 2 . This method is used to detect the catalytic stability of the two-dimensional Turing structure high-entropy perovskite material in the three-in-series water-splitting electrolyzer.

[0118] In some embodiments of the present application, the start-stop test is alternately switched between a current density of 0 mA / cm 2 and 250 mA / cm 2 , with a time of 200 s each time and a cycle of 40 times. This method is used to detect the catalytic stability of the two-dimensional Turing structure high-entropy perovskite material in repeated start-stop.

[0119] In some embodiments of the present application, the power fluctuation test is alternately switched between a current density of 10 mA / cm 2 , 100 mA / cm 2 and 250 mA / cm 2 , with a time of 100 s each time and a cycle of 100 times. This method is used to detect the catalytic stability of the two-dimensional Turing structure high-entropy perovskite material under phased current density steps.

[0120] In some embodiments of the present application, the power fluctuation test is alternately switched between a current density of 1 mA / cm 2 and 250 mA / cm 2 , with a time of 100 s each time and a cycle of 200 times. This method is used to detect the catalytic stability of the two-dimensional Turing structure high-entropy perovskite material under larger power fluctuations.

[0121] The present application will be described in detail below with reference to specific embodiments.

[0122] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present application are conventional reagents, methods, instruments and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0123] Example 1

[0124] This example provides a two-dimensional Turing structure high-entropy perovskite material, and a preparation method thereof is as follows:

[0125] The HEOs-Gly was synthesized by sol-gel combined with one-step calcination, and the specific process was as follows:

[0126] 20 mL of deionized water was placed in a beaker, and 54 mg of glycine solid was dissolved in the deionized water. The temperature of the heating table was adjusted to 45℃, and 0.6 mL of 0.03M Mn(NO3)2, Fe(NO3)3, Co(NO3)2, Ni(NO3)2, Cu(NO3)2 solution and 3 mL of 0.03M La(NO3)3 solution were added to the above chelating agent solution under vigorous stirring, and stirred for 1 h. Then, ammonia water was added dropwise to adjust the pH to 10, and then the stirring temperature was raised to 92℃, and the stirring was continued until the metal organic gel was formed.

[0127] The metal organic gel formed by the above method was placed in an oven and dried at 120℃ for 12 h to form a dry gel. Then the dry gel was placed in a muffle furnace, and the temperature was raised to 800℃ at a rate of 10℃ / min and kept at this temperature for 2 h. The flaky solid formed after calcination was a two-dimensional Turing structure high-entropy perovskite material (HEOs-Gly).

[0128] Characterization results:

[0129] Figure 1 FIG. 1 is a scanning electron microscope photograph of HEOs-Gly synthesized in Example 1, and the scales in A and B are 5 μm and 1 μm, respectively. As can be seen from FIG. A, the morphology of HEOs-Gly is a typical flaky morphology, and the lateral size is 5-10 μm. As can be seen from B, HEOs-Gly has a typical Turing structure, and the nanoparticles are arranged in cross-linking, and there are gaps between the nanoparticles.

[0130] Figure 2 FIG. 2 is a side scanning electron microscope photograph of HEOs-Gly synthesized in Example 1, and the scale is 1 μm. As can be seen from the figure, the thickness of HEOs-Gly is about 70 nm, which is a two-dimensional structure.

[0131] Figure 3 FIG. 3 is a transmission electron microscope photograph of HEOs-Gly synthesized in Example 1 and a high-resolution lattice fringe. A is a transmission electron microscope photograph of Turing particles of HEOs-Gly with a scale of 100 nm, and from the figure it can be seen that the constituent unit of HEOs-Gly is a coral-like particle. B is a high-resolution lattice fringe of HEOs-Gly at the grain boundary, and the lattice fringes correspond to (211) and (110), respectively, which correspond to the crystal faces of the perovskite structure.

[0132] Figure 4 are another set of TEM images and high-resolution lattice fringes of HEOs-Gly synthesized in Example 1. The TEM images of A and B have a scale bar of 200 nm, and the high-resolution lattice fringes have a scale bar of 5 nm. As can be seen from the images, the (200), (111), (211), and (110) planes are distributed at the grain boundaries. Also corresponding to the planes of the perovskite structure.

[0133] Figure 5 are the results of the dissipative electrochemical quartz crystal microbalance (EQCM-D) test of HEOs-Gly synthesized in Example 1. A is the result of the resonance frequency (f) of the quartz crystal chip sensor coated with HEOs-Gly powder collected during the cyclic voltammetry (CV) test. The overall mass of HEOs-Gly increases after CV, confirming that the catalyst is restructured at a certain potential and that the intermediate in the OER process is accelerated to adsorb. B is the result of the dissipation factor (D) of the quartz crystal chip sensor collected during the CV test. By applying a potential to HEOs-Gly, the catalyst becomes more flexible, which helps to enhance the ability of the water splitting electrode to adapt to power fluctuations and frequent start-stop.

[0134] Three-in-line water splitting electrolyzer performance test:

[0135] The performance of the HEOs-Gly electrode sheet was tested using a three-in-line water splitting electrolyzer, as shown in Figure 6As shown, the three-stage water splitting electrolyzer includes an anode plate 110, an anode plate 120, and an anode gas chamber 130. The anode plate 120 separates the anode plate 110 and the anode gas chamber 130, and also supports the nickel foam electrode. The anode gas chamber 130 and the cathode gas chamber 132 are separated by a diaphragm 131, which also separates the fluid and gas between the anode and cathode, thus allowing only ion exchange to occur at the anode and cathode. The diaphragm is made of PPS material, capable of withstanding strong alkalis (up to 30 wt.%) and electrolytes at approximately 100°C. A bipolar plate 140 separates the cathode gas chamber 132 on one side from the anode gas chamber 130 on the other side, allowing hydrogen evolution and oxygen evolution reactions to occur separately on either side of the bipolar plate without interference. Similarly, the cathode plate 160 and the rightmost cathode gas chamber 132 are separated by a cathode plate 150, which also supports the nickel foam. The anode plate connector 121 connects to the working electrode of the electrochemical workstation (Chenhua CHI760E), and the cathode plate connector 151 connects to the counter electrode and reference electrode of the electrochemical workstation, together forming a dual-electrode system to supply power to the electrolytic cell. The anode electrolyte is introduced through the anode chamber electrolyte flow rate controller (Longer, Halma plc), entering through the anode electrolyte inlet 111 and exiting through the anode electrolyte outlet. Similarly, the cathode electrolyte is introduced through the cathode electrolyte flow rate controller, entering through the cathode electrolyte inlet 161 and exiting through the cathode electrolyte outlet. Both the cathode and anode electrolytes flow from bottom to top, facilitating the elimination of air bubbles in the electrolyte.

[0136] The HEOs-Gly provided in Example 1 was selected as the anode catalyst on the working electrode for performance testing of a three-series water splitting electrolyzer.

[0137] The stability test results of the HEOs-Gly electrode are as follows: Figure 7 As shown, the test conditions were 60℃ and the KOH concentration of the electrolyte was 6 mol / L. The tests revealed that the HEOs-Gly anode electrode exhibited excellent stability at 250 mA / cm². 2 The catalyst was stably catalyzed for 220 h at a given current density, with a decay rate of approximately 4.3% in the first 100 h and 8.3% after 220 h. The excellent stability of HEOs-Gly is attributed to the adsorption of active species and the reconstruction of active sites after the application of the potential.

[0138] The start-up and shutdown test results of the HEOs-Gly electrode are as follows: Figure 8 As shown, the test conditions were 60℃ and the KOH concentration of the electrolyte was 6 mol / L. By setting 0 mA / cm... 2 and 250mA / cm 2The current was switched back and forth to simulate the start-stop of the electrolytic cell in industrial operation, each period being 200 s. The test found that the HEOs-Gly electrode could quickly start after shutdown and reach potential stability within 20-30 s. After 40 start-stop cycles, the HEOs-Gly electrode still maintained a high climbing rate. The excellent start-stop adaptability of HEOs-Gly benefited from the improved reverse current resistance brought by the increased flexibility of the catalyst after the applied potential.

[0139] The power fluctuation test of the HEOs-Gly electrode is shown in Figure 9 , and the test conditions are 60℃ and 6mol / L of KOH concentration in the electrolyte. By switching back and forth at three current densities of 10mA / cm 2 , 100mA / cm 2 and 250mA / cm 2 , the start-stop of the electrolytic cell in industrial operation is simulated, each period being 100 s. The test found that the HEOs-Gly electrode maintained high stability and fast climbing rate under the step change of current density, especially at high current density. The enhanced flexibility of HEOs-Gly after the applied potential and the optimization of the adsorption behavior of intermediates in the OER process by the rich active sites.

[0140] The power climbing test of the HEOs-Gly electrode is shown in Figure 10 , and the test conditions are 60℃ and 6mol / L of KOH concentration in the electrolyte. The current density is quickly switched (100s) between 1mA / cm 2 and 250mA / cm 2 . The test found that the HEOs-Gly electrode could quickly maintain stability under 1000 times power surge, with a climbing time of about 20s, and still maintained a fast climbing rate after 200 cycles.

[0141] Example 2

[0142] This example provides a high-entropy perovskite material (HEOs-Ala) with Turing structure. The difference from Example 1 is that, as shown in Figure 11 , the material has a thicker sheet-like morphology with a pore size of about 100-150 nm. The difference between the preparation method and Example 1 is that 78mg of β-alanine is used as a chelating agent instead of glycine, and the obtained morphology also has Turing structure. OER test shows that HEOs-Ala has a lower OER overpotential and is an ideal water splitting electrocatalyst.

[0143] Example 3

[0144] This example provides a high-entropy perovskite material (HEOs-Cyc) with Turing structure. The difference from Example 1 is that, as shown in Figure 12As shown, the material has a relatively thick sheet-like morphology, with pore sizes of about 100-300 nm. The preparation method differs from that of Example 1 in that 97 mg of glycine dipeptide is used as a chelating agent instead of glycine, and the resulting morphology also has a Turing structure. OER tests show that HEOs-Cyc has a lower OER overpotential and is an ideal water decomposition electrocatalyst.

[0145] Comparative Example 1

[0146] This comparative example provides a non-Turing structure high-entropy perovskite material (HEOs-Eth), which differs from Examples 1-3 in that, as shown in Figure 13 The material does not have a sheet-like structure, but rather a bulk structure. The preparation method differs from that of Example 1 in that an equimolar amount of ethylamine is used as a chelating agent instead of glycine. SEM tests show that HEOs-Eth is in a bulk accumulation state and does not have a pore structure, with irregular particles in a close-packed arrangement. OER tests show that HEOs-Eth has a higher OER overpotential and poorer water decomposition performance.

[0147] Comparative Example 2

[0148] This comparative example provides a non-Turing structure high-entropy perovskite material (HEOs-Pla), which differs from Examples 1-3 in that, as shown in Figure 14 The material does not have a sheet-like structure, but rather a bulk structure. The preparation method differs from that of Example 1 in that an equimolar amount of propionic acid is used as a chelating agent instead of glycine. SEM tests show that HEOs-Pla is in a bulk accumulation state and only has some mesopores, with irregular square particles. OER tests show that HEOs-Pla has a higher OER overpotential and poorer water decomposition performance.

[0149] The linear voltammetry scan curves of Examples 1-3 and Comparative Examples 1-2 are shown in Figure 15 As can be seen from the figure, at the same potential, the reaction rate of the materials of Examples 1-3 is faster and the catalytic activity is higher than that of Comparative Examples 1-2.

[0150] Comparative Example 3

[0151] This comparative example provides a non-Turing structure high-entropy perovskite material (HEOs-Gly+CA), which differs from Examples 1-3 in that, as shown in Figure 16 The material does not have a sheet-like structure, but rather a bulk structure. The preparation method differs from that of Example 1 in that an equimolar amount of glycine and citric acid is used as a mixed chelating agent. When citric acid with the same metal chelating characteristics is introduced, it competes with glycine, which is not conducive to the formation of stable and uniform metal-organic gels, and is not conducive to the formation of single-phase and uniform two-dimensional high-entropy perovskite oxides.

[0152] Comparative Example 4

[0153] This comparative example provides a non-Turing structure high-entropy perovskite material (HEOs-EDTA+CA), which differs from Examples 1-3 in that, as Figure 17 As shown, this material does not have a sheet-like structure, but rather a bulk structure. The difference between the preparation method and Example 1 is that an equimolar mixture of ethylenediaminetetraacetic acid and citric acid is used as a chelating agent, similar to that in Example 1. When citric acid and ethylenediaminetetraacetic acid, which have the same metal chelating properties, are used together as chelating agents, they will compete for the metal ions, which is not conducive to the formation of a stable and uniform organometallic gel, nor to the formation of a single-phase, uniform two-dimensional high-entropy perovskite oxide.

[0154] Comparative Example 5

[0155] This comparative example provides a non-Turing structure high-entropy perovskite material (HEOs-EDTA+Gly), which differs from Examples 1-3 in that, as Figure 18 As shown, this material does not possess a sheet-like structure but rather a bulk structure, and its internal constituent units are not uniformly ordered Turing nanoparticles. The difference between the preparation method and Example 1 is that an equimolar mixture of ethylenediaminetetraacetic acid (EDTA) and glycine is used as a chelating agent, similar to that in Example 1. When glycine and EDTA, which have the same metal-chelating properties, are used together as chelating agents, they will compete for the metal ions, which is not conducive to the formation of a stable and uniform metal-organic gel, nor to the formation of a single-phase, uniform two-dimensional Turing high-entropy perovskite oxide.

[0156] The novel two-dimensional Turing-structured high-entropy perovskite material provided by this invention exhibits a typical two-dimensional Turing morphology, with its constituent units being staggered Turing nanoparticles. Upon application of an electric potential, the surface of the two-dimensional Turing-structured high-entropy perovskite material undergoes reconstruction, thereby improving the adsorption of intermediate species, while simultaneously enhancing the catalyst's flexibility. The unique morphology of this novel two-dimensional Turing-structured high-entropy perovskite material endows it with excellent electrocatalytic water splitting performance and adaptability and stability under fluctuating power, demonstrating broad prospects for industrial applications.

[0157] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A high-entropy perovskite material, characterized in that, The chemical formula is ABO3, where the A-site element is La, and the B-site elements are Mn, Fe, Co, Ni, and Cu. The molar ratio of Mn, Fe, Co, Ni, and Cu is 1:1:1:1:1; The molar ratio of the total amount of La element to the total amount of transition metal element at the B site is (1.1-0.9):1; The high-entropy perovskite material has a two-dimensional Turing structure, with nanoparticles arranged in a cross-linked pattern and gaps between the particles.

2. The high-entropy perovskite material according to claim 1, characterized in that, The high-entropy perovskite material has a lateral dimension of 5-10 μm and a thickness of 70-100 nm.

3. The high-entropy perovskite material according to claim 1, characterized in that, The high-entropy perovskite material has multiple sets of different crystal planes, and different lattice fringes on both sides of the grain boundaries.

4. A method for preparing the high-entropy perovskite material according to any one of claims 1-3, characterized in that, Includes the following steps: Add the metal ions corresponding to the A and B sites to the chelating agent solution, stir evenly, add ammonia water and adjust the pH of the solution to 9-11, increase the stirring temperature, and continue stirring until the metal-organic gel is formed. The metal-organic gel is dried to form a dry gel, and the dry gel is calcined to form the high-entropy perovskite material. During the heating and calcination process, the heating rate is 8-10℃ / min, and the temperature is raised to 750-850℃ and maintained at that temperature for 2-3 hours. The chelating agent is glycine; The molar ratio of the chelating agent to the total amount of metal ions corresponding to the A-site and B-site elements is (1-10):

1.

5. The method for preparing high-entropy perovskite material according to claim 4, characterized in that, Specifically, the following steps are included: Add the metal ions corresponding to the A and B sites to the chelating agent solution and stir at 40-50℃ for 1-3 hours. Then, add ammonia water and adjust the pH of the solution to 9-11. Then, raise the stirring temperature to 85-95℃ and continue stirring until the metal-organic gel is formed. The metal-organic gel is dried at 100-120°C to form a dry gel, and the dry gel is then calcined to form the high-entropy perovskite material.

6. An application of the high-entropy perovskite material according to any one of claims 1-3, characterized in that, The high-entropy perovskite material was used as an anode oxygen evolution reaction catalyst in an electrocatalytic water splitting system.

7. The application of the high-entropy perovskite material according to claim 6, characterized in that, The high-entropy perovskite material is loaded onto a conductive substrate as an anode oxygen evolution reaction catalyst to obtain a working electrode. The working electrode is placed in the anode chamber of an alkaline water splitting electrolyzer as an anode for use in an electrocatalytic water splitting system.

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